#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h>
+#include <linux/interrupt.h>
#include <linux/signal.h>
#include <linux/completion.h>
#include <linux/workqueue.h>
#include <linux/moduleparam.h>
#include <linux/uaccess.h>
#include <linux/sched/isolation.h>
+#include <linux/sched/debug.h>
#include <linux/nmi.h>
+#include <linux/kvm_para.h>
+#include <linux/delay.h>
+#include <linux/irq_work.h>
#include "workqueue_internal.h"
-enum {
+enum worker_pool_flags {
/*
* worker_pool flags
*
* Note that DISASSOCIATED should be flipped only while holding
* wq_pool_attach_mutex to avoid changing binding state while
* worker_attach_to_pool() is in progress.
+ *
+ * As there can only be one concurrent BH execution context per CPU, a
+ * BH pool is per-CPU and always DISASSOCIATED.
*/
- POOL_MANAGER_ACTIVE = 1 << 0, /* being managed */
+ POOL_BH = 1 << 0, /* is a BH pool */
+ POOL_MANAGER_ACTIVE = 1 << 1, /* being managed */
POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
+ POOL_BH_DRAINING = 1 << 3, /* draining after CPU offline */
+};
+enum worker_flags {
/* worker flags */
WORKER_DIE = 1 << 1, /* die die die */
WORKER_IDLE = 1 << 2, /* is idle */
WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE |
WORKER_UNBOUND | WORKER_REBOUND,
+};
+
+enum work_cancel_flags {
+ WORK_CANCEL_DELAYED = 1 << 0, /* canceling a delayed_work */
+};
+enum wq_internal_consts {
NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */
UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */
RESCUER_NICE_LEVEL = MIN_NICE,
HIGHPRI_NICE_LEVEL = MIN_NICE,
- WQ_NAME_LEN = 24,
+ WQ_NAME_LEN = 32,
};
+/*
+ * We don't want to trap softirq for too long. See MAX_SOFTIRQ_TIME and
+ * MAX_SOFTIRQ_RESTART in kernel/softirq.c. These are macros because
+ * msecs_to_jiffies() can't be an initializer.
+ */
+#define BH_WORKER_JIFFIES msecs_to_jiffies(2)
+#define BH_WORKER_RESTARTS 10
+
/*
* Structure fields follow one of the following exclusion rules.
*
*
* L: pool->lock protected. Access with pool->lock held.
*
- * X: During normal operation, modification requires pool->lock and should
- * be done only from local cpu. Either disabling preemption on local
- * cpu or grabbing pool->lock is enough for read access. If
- * POOL_DISASSOCIATED is set, it's identical to L.
+ * LN: pool->lock and wq_node_nr_active->lock protected for writes. Either for
+ * reads.
+ *
+ * K: Only modified by worker while holding pool->lock. Can be safely read by
+ * self, while holding pool->lock or from IRQ context if %current is the
+ * kworker.
+ *
+ * S: Only modified by worker self.
*
* A: wq_pool_attach_mutex protected.
*
*
* WR: wq->mutex protected for writes. RCU protected for reads.
*
+ * WO: wq->mutex protected for writes. Updated with WRITE_ONCE() and can be read
+ * with READ_ONCE() without locking.
+ *
* MD: wq_mayday_lock protected.
+ *
+ * WD: Used internally by the watchdog.
*/
/* struct worker is defined in workqueue_internal.h */
struct worker_pool {
- spinlock_t lock; /* the pool lock */
+ raw_spinlock_t lock; /* the pool lock */
int cpu; /* I: the associated cpu */
int node; /* I: the associated node ID */
int id; /* I: pool ID */
- unsigned int flags; /* X: flags */
+ unsigned int flags; /* L: flags */
unsigned long watchdog_ts; /* L: watchdog timestamp */
+ bool cpu_stall; /* WD: stalled cpu bound pool */
+
+ /*
+ * The counter is incremented in a process context on the associated CPU
+ * w/ preemption disabled, and decremented or reset in the same context
+ * but w/ pool->lock held. The readers grab pool->lock and are
+ * guaranteed to see if the counter reached zero.
+ */
+ int nr_running;
struct list_head worklist; /* L: list of pending works */
int nr_workers; /* L: total number of workers */
int nr_idle; /* L: currently idle workers */
- struct list_head idle_list; /* X: list of idle workers */
+ struct list_head idle_list; /* L: list of idle workers */
struct timer_list idle_timer; /* L: worker idle timeout */
- struct timer_list mayday_timer; /* L: SOS timer for workers */
+ struct work_struct idle_cull_work; /* L: worker idle cleanup */
+
+ struct timer_list mayday_timer; /* L: SOS timer for workers */
/* a workers is either on busy_hash or idle_list, or the manager */
DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER);
struct worker *manager; /* L: purely informational */
struct list_head workers; /* A: attached workers */
+ struct list_head dying_workers; /* A: workers about to die */
struct completion *detach_completion; /* all workers detached */
struct ida worker_ida; /* worker IDs for task name */
struct hlist_node hash_node; /* PL: unbound_pool_hash node */
int refcnt; /* PL: refcnt for unbound pools */
- /*
- * The current concurrency level. As it's likely to be accessed
- * from other CPUs during try_to_wake_up(), put it in a separate
- * cacheline.
- */
- atomic_t nr_running ____cacheline_aligned_in_smp;
-
/*
* Destruction of pool is RCU protected to allow dereferences
* from get_work_pool().
*/
struct rcu_head rcu;
-} ____cacheline_aligned_in_smp;
+};
+
+/*
+ * Per-pool_workqueue statistics. These can be monitored using
+ * tools/workqueue/wq_monitor.py.
+ */
+enum pool_workqueue_stats {
+ PWQ_STAT_STARTED, /* work items started execution */
+ PWQ_STAT_COMPLETED, /* work items completed execution */
+ PWQ_STAT_CPU_TIME, /* total CPU time consumed */
+ PWQ_STAT_CPU_INTENSIVE, /* wq_cpu_intensive_thresh_us violations */
+ PWQ_STAT_CM_WAKEUP, /* concurrency-management worker wakeups */
+ PWQ_STAT_REPATRIATED, /* unbound workers brought back into scope */
+ PWQ_STAT_MAYDAY, /* maydays to rescuer */
+ PWQ_STAT_RESCUED, /* linked work items executed by rescuer */
+
+ PWQ_NR_STATS,
+};
/*
- * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS
+ * The per-pool workqueue. While queued, bits below WORK_PWQ_SHIFT
* of work_struct->data are used for flags and the remaining high bits
* point to the pwq; thus, pwqs need to be aligned at two's power of the
* number of flag bits.
int refcnt; /* L: reference count */
int nr_in_flight[WORK_NR_COLORS];
/* L: nr of in_flight works */
+ bool plugged; /* L: execution suspended */
+
+ /*
+ * nr_active management and WORK_STRUCT_INACTIVE:
+ *
+ * When pwq->nr_active >= max_active, new work item is queued to
+ * pwq->inactive_works instead of pool->worklist and marked with
+ * WORK_STRUCT_INACTIVE.
+ *
+ * All work items marked with WORK_STRUCT_INACTIVE do not participate in
+ * nr_active and all work items in pwq->inactive_works are marked with
+ * WORK_STRUCT_INACTIVE. But not all WORK_STRUCT_INACTIVE work items are
+ * in pwq->inactive_works. Some of them are ready to run in
+ * pool->worklist or worker->scheduled. Those work itmes are only struct
+ * wq_barrier which is used for flush_work() and should not participate
+ * in nr_active. For non-barrier work item, it is marked with
+ * WORK_STRUCT_INACTIVE iff it is in pwq->inactive_works.
+ */
int nr_active; /* L: nr of active works */
- int max_active; /* L: max active works */
- struct list_head delayed_works; /* L: delayed works */
+ struct list_head inactive_works; /* L: inactive works */
+ struct list_head pending_node; /* LN: node on wq_node_nr_active->pending_pwqs */
struct list_head pwqs_node; /* WR: node on wq->pwqs */
struct list_head mayday_node; /* MD: node on wq->maydays */
+ u64 stats[PWQ_NR_STATS];
+
/*
- * Release of unbound pwq is punted to system_wq. See put_pwq()
- * and pwq_unbound_release_workfn() for details. pool_workqueue
- * itself is also RCU protected so that the first pwq can be
- * determined without grabbing wq->mutex.
+ * Release of unbound pwq is punted to a kthread_worker. See put_pwq()
+ * and pwq_release_workfn() for details. pool_workqueue itself is also
+ * RCU protected so that the first pwq can be determined without
+ * grabbing wq->mutex.
*/
- struct work_struct unbound_release_work;
+ struct kthread_work release_work;
struct rcu_head rcu;
-} __aligned(1 << WORK_STRUCT_FLAG_BITS);
+} __aligned(1 << WORK_STRUCT_PWQ_SHIFT);
/*
* Structure used to wait for workqueue flush.
struct wq_device;
+/*
+ * Unlike in a per-cpu workqueue where max_active limits its concurrency level
+ * on each CPU, in an unbound workqueue, max_active applies to the whole system.
+ * As sharing a single nr_active across multiple sockets can be very expensive,
+ * the counting and enforcement is per NUMA node.
+ *
+ * The following struct is used to enforce per-node max_active. When a pwq wants
+ * to start executing a work item, it should increment ->nr using
+ * tryinc_node_nr_active(). If acquisition fails due to ->nr already being over
+ * ->max, the pwq is queued on ->pending_pwqs. As in-flight work items finish
+ * and decrement ->nr, node_activate_pending_pwq() activates the pending pwqs in
+ * round-robin order.
+ */
+struct wq_node_nr_active {
+ int max; /* per-node max_active */
+ atomic_t nr; /* per-node nr_active */
+ raw_spinlock_t lock; /* nests inside pool locks */
+ struct list_head pending_pwqs; /* LN: pwqs with inactive works */
+};
+
/*
* The externally visible workqueue. It relays the issued work items to
* the appropriate worker_pool through its pool_workqueues.
struct list_head flusher_overflow; /* WQ: flush overflow list */
struct list_head maydays; /* MD: pwqs requesting rescue */
- struct worker *rescuer; /* I: rescue worker */
+ struct worker *rescuer; /* MD: rescue worker */
int nr_drainers; /* WQ: drain in progress */
- int saved_max_active; /* WQ: saved pwq max_active */
+
+ /* See alloc_workqueue() function comment for info on min/max_active */
+ int max_active; /* WO: max active works */
+ int min_active; /* WO: min active works */
+ int saved_max_active; /* WQ: saved max_active */
+ int saved_min_active; /* WQ: saved min_active */
struct workqueue_attrs *unbound_attrs; /* PW: only for unbound wqs */
- struct pool_workqueue *dfl_pwq; /* PW: only for unbound wqs */
+ struct pool_workqueue __rcu *dfl_pwq; /* PW: only for unbound wqs */
#ifdef CONFIG_SYSFS
struct wq_device *wq_dev; /* I: for sysfs interface */
/* hot fields used during command issue, aligned to cacheline */
unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */
- struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */
- struct pool_workqueue __rcu *numa_pwq_tbl[]; /* PWR: unbound pwqs indexed by node */
+ struct pool_workqueue __percpu __rcu **cpu_pwq; /* I: per-cpu pwqs */
+ struct wq_node_nr_active *node_nr_active[]; /* I: per-node nr_active */
};
-static struct kmem_cache *pwq_cache;
+/*
+ * Each pod type describes how CPUs should be grouped for unbound workqueues.
+ * See the comment above workqueue_attrs->affn_scope.
+ */
+struct wq_pod_type {
+ int nr_pods; /* number of pods */
+ cpumask_var_t *pod_cpus; /* pod -> cpus */
+ int *pod_node; /* pod -> node */
+ int *cpu_pod; /* cpu -> pod */
+};
-static cpumask_var_t *wq_numa_possible_cpumask;
- /* possible CPUs of each node */
+static const char *wq_affn_names[WQ_AFFN_NR_TYPES] = {
+ [WQ_AFFN_DFL] = "default",
+ [WQ_AFFN_CPU] = "cpu",
+ [WQ_AFFN_SMT] = "smt",
+ [WQ_AFFN_CACHE] = "cache",
+ [WQ_AFFN_NUMA] = "numa",
+ [WQ_AFFN_SYSTEM] = "system",
+};
-static bool wq_disable_numa;
-module_param_named(disable_numa, wq_disable_numa, bool, 0444);
+/*
+ * Per-cpu work items which run for longer than the following threshold are
+ * automatically considered CPU intensive and excluded from concurrency
+ * management to prevent them from noticeably delaying other per-cpu work items.
+ * ULONG_MAX indicates that the user hasn't overridden it with a boot parameter.
+ * The actual value is initialized in wq_cpu_intensive_thresh_init().
+ */
+static unsigned long wq_cpu_intensive_thresh_us = ULONG_MAX;
+module_param_named(cpu_intensive_thresh_us, wq_cpu_intensive_thresh_us, ulong, 0644);
+#ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT
+static unsigned int wq_cpu_intensive_warning_thresh = 4;
+module_param_named(cpu_intensive_warning_thresh, wq_cpu_intensive_warning_thresh, uint, 0644);
+#endif
/* see the comment above the definition of WQ_POWER_EFFICIENT */
static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT);
module_param_named(power_efficient, wq_power_efficient, bool, 0444);
static bool wq_online; /* can kworkers be created yet? */
+static bool wq_topo_initialized __read_mostly = false;
+
+static struct kmem_cache *pwq_cache;
-static bool wq_numa_enabled; /* unbound NUMA affinity enabled */
+static struct wq_pod_type wq_pod_types[WQ_AFFN_NR_TYPES];
+static enum wq_affn_scope wq_affn_dfl = WQ_AFFN_CACHE;
-/* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */
-static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf;
+/* buf for wq_update_unbound_pod_attrs(), protected by CPU hotplug exclusion */
+static struct workqueue_attrs *wq_update_pod_attrs_buf;
static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */
static DEFINE_MUTEX(wq_pool_attach_mutex); /* protects worker attach/detach */
-static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */
-static DECLARE_WAIT_QUEUE_HEAD(wq_manager_wait); /* wait for manager to go away */
+static DEFINE_RAW_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */
+/* wait for manager to go away */
+static struct rcuwait manager_wait = __RCUWAIT_INITIALIZER(manager_wait);
static LIST_HEAD(workqueues); /* PR: list of all workqueues */
static bool workqueue_freezing; /* PL: have wqs started freezing? */
-/* PL: allowable cpus for unbound wqs and work items */
+/* PL&A: allowable cpus for unbound wqs and work items */
static cpumask_var_t wq_unbound_cpumask;
+/* PL: user requested unbound cpumask via sysfs */
+static cpumask_var_t wq_requested_unbound_cpumask;
+
+/* PL: isolated cpumask to be excluded from unbound cpumask */
+static cpumask_var_t wq_isolated_cpumask;
+
+/* for further constrain wq_unbound_cpumask by cmdline parameter*/
+static struct cpumask wq_cmdline_cpumask __initdata;
+
/* CPU where unbound work was last round robin scheduled from this CPU */
static DEFINE_PER_CPU(int, wq_rr_cpu_last);
#endif
module_param_named(debug_force_rr_cpu, wq_debug_force_rr_cpu, bool, 0644);
+/* to raise softirq for the BH worker pools on other CPUs */
+static DEFINE_PER_CPU_SHARED_ALIGNED(struct irq_work [NR_STD_WORKER_POOLS],
+ bh_pool_irq_works);
+
+/* the BH worker pools */
+static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS],
+ bh_worker_pools);
+
/* the per-cpu worker pools */
-static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], cpu_worker_pools);
+static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS],
+ cpu_worker_pools);
static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */
/* I: attributes used when instantiating ordered pools on demand */
static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS];
-struct workqueue_struct *system_wq __read_mostly;
+/*
+ * Used to synchronize multiple cancel_sync attempts on the same work item. See
+ * work_grab_pending() and __cancel_work_sync().
+ */
+static DECLARE_WAIT_QUEUE_HEAD(wq_cancel_waitq);
+
+/*
+ * I: kthread_worker to release pwq's. pwq release needs to be bounced to a
+ * process context while holding a pool lock. Bounce to a dedicated kthread
+ * worker to avoid A-A deadlocks.
+ */
+static struct kthread_worker *pwq_release_worker __ro_after_init;
+
+struct workqueue_struct *system_wq __ro_after_init;
EXPORT_SYMBOL(system_wq);
-struct workqueue_struct *system_highpri_wq __read_mostly;
+struct workqueue_struct *system_highpri_wq __ro_after_init;
EXPORT_SYMBOL_GPL(system_highpri_wq);
-struct workqueue_struct *system_long_wq __read_mostly;
+struct workqueue_struct *system_long_wq __ro_after_init;
EXPORT_SYMBOL_GPL(system_long_wq);
-struct workqueue_struct *system_unbound_wq __read_mostly;
+struct workqueue_struct *system_unbound_wq __ro_after_init;
EXPORT_SYMBOL_GPL(system_unbound_wq);
-struct workqueue_struct *system_freezable_wq __read_mostly;
+struct workqueue_struct *system_freezable_wq __ro_after_init;
EXPORT_SYMBOL_GPL(system_freezable_wq);
-struct workqueue_struct *system_power_efficient_wq __read_mostly;
+struct workqueue_struct *system_power_efficient_wq __ro_after_init;
EXPORT_SYMBOL_GPL(system_power_efficient_wq);
-struct workqueue_struct *system_freezable_power_efficient_wq __read_mostly;
+struct workqueue_struct *system_freezable_power_efficient_wq __ro_after_init;
EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq);
+struct workqueue_struct *system_bh_wq;
+EXPORT_SYMBOL_GPL(system_bh_wq);
+struct workqueue_struct *system_bh_highpri_wq;
+EXPORT_SYMBOL_GPL(system_bh_highpri_wq);
static int worker_thread(void *__worker);
static void workqueue_sysfs_unregister(struct workqueue_struct *wq);
+static void show_pwq(struct pool_workqueue *pwq);
+static void show_one_worker_pool(struct worker_pool *pool);
#define CREATE_TRACE_POINTS
#include <trace/events/workqueue.h>
#define assert_rcu_or_pool_mutex() \
- RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
+ RCU_LOCKDEP_WARN(!rcu_read_lock_any_held() && \
!lockdep_is_held(&wq_pool_mutex), \
"RCU or wq_pool_mutex should be held")
-#define assert_rcu_or_wq_mutex(wq) \
- RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
- !lockdep_is_held(&wq->mutex), \
- "RCU or wq->mutex should be held")
-
#define assert_rcu_or_wq_mutex_or_pool_mutex(wq) \
- RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
+ RCU_LOCKDEP_WARN(!rcu_read_lock_any_held() && \
!lockdep_is_held(&wq->mutex) && \
!lockdep_is_held(&wq_pool_mutex), \
"RCU, wq->mutex or wq_pool_mutex should be held")
+#define for_each_bh_worker_pool(pool, cpu) \
+ for ((pool) = &per_cpu(bh_worker_pools, cpu)[0]; \
+ (pool) < &per_cpu(bh_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
+ (pool)++)
+
#define for_each_cpu_worker_pool(pool, cpu) \
for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \
(pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
* ignored.
*/
#define for_each_pwq(pwq, wq) \
- list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \
- if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \
- else
+ list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node, \
+ lockdep_is_held(&(wq->mutex)))
#ifdef CONFIG_DEBUG_OBJECTS_WORK
-static struct debug_obj_descr work_debug_descr;
+static const struct debug_obj_descr work_debug_descr;
static void *work_debug_hint(void *addr)
{
}
}
-static struct debug_obj_descr work_debug_descr = {
+static const struct debug_obj_descr work_debug_descr = {
.name = "work_struct",
.debug_hint = work_debug_hint,
.is_static_object = work_is_static_object,
#endif
/**
- * worker_pool_assign_id - allocate ID and assing it to @pool
+ * worker_pool_assign_id - allocate ID and assign it to @pool
* @pool: the pool pointer of interest
*
* Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned
return ret;
}
+static struct pool_workqueue __rcu **
+unbound_pwq_slot(struct workqueue_struct *wq, int cpu)
+{
+ if (cpu >= 0)
+ return per_cpu_ptr(wq->cpu_pwq, cpu);
+ else
+ return &wq->dfl_pwq;
+}
+
+/* @cpu < 0 for dfl_pwq */
+static struct pool_workqueue *unbound_pwq(struct workqueue_struct *wq, int cpu)
+{
+ return rcu_dereference_check(*unbound_pwq_slot(wq, cpu),
+ lockdep_is_held(&wq_pool_mutex) ||
+ lockdep_is_held(&wq->mutex));
+}
+
/**
- * unbound_pwq_by_node - return the unbound pool_workqueue for the given node
- * @wq: the target workqueue
- * @node: the node ID
- *
- * This must be called with any of wq_pool_mutex, wq->mutex or RCU
- * read locked.
- * If the pwq needs to be used beyond the locking in effect, the caller is
- * responsible for guaranteeing that the pwq stays online.
+ * unbound_effective_cpumask - effective cpumask of an unbound workqueue
+ * @wq: workqueue of interest
*
- * Return: The unbound pool_workqueue for @node.
+ * @wq->unbound_attrs->cpumask contains the cpumask requested by the user which
+ * is masked with wq_unbound_cpumask to determine the effective cpumask. The
+ * default pwq is always mapped to the pool with the current effective cpumask.
*/
-static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq,
- int node)
+static struct cpumask *unbound_effective_cpumask(struct workqueue_struct *wq)
{
- assert_rcu_or_wq_mutex_or_pool_mutex(wq);
-
- /*
- * XXX: @node can be NUMA_NO_NODE if CPU goes offline while a
- * delayed item is pending. The plan is to keep CPU -> NODE
- * mapping valid and stable across CPU on/offlines. Once that
- * happens, this workaround can be removed.
- */
- if (unlikely(node == NUMA_NO_NODE))
- return wq->dfl_pwq;
-
- return rcu_dereference_raw(wq->numa_pwq_tbl[node]);
+ return unbound_pwq(wq, -1)->pool->attrs->__pod_cpumask;
}
static unsigned int work_color_to_flags(int color)
return color << WORK_STRUCT_COLOR_SHIFT;
}
-static int get_work_color(struct work_struct *work)
+static int get_work_color(unsigned long work_data)
{
- return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) &
+ return (work_data >> WORK_STRUCT_COLOR_SHIFT) &
((1 << WORK_STRUCT_COLOR_BITS) - 1);
}
* contain the pointer to the queued pwq. Once execution starts, the flag
* is cleared and the high bits contain OFFQ flags and pool ID.
*
- * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling()
- * and clear_work_data() can be used to set the pwq, pool or clear
- * work->data. These functions should only be called while the work is
- * owned - ie. while the PENDING bit is set.
+ * set_work_pwq(), set_work_pool_and_clear_pending() and mark_work_canceling()
+ * can be used to set the pwq, pool or clear work->data. These functions should
+ * only be called while the work is owned - ie. while the PENDING bit is set.
*
* get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq
* corresponding to a work. Pool is available once the work has been
* but stay off timer and worklist for arbitrarily long and nobody should
* try to steal the PENDING bit.
*/
-static inline void set_work_data(struct work_struct *work, unsigned long data,
- unsigned long flags)
+static inline void set_work_data(struct work_struct *work, unsigned long data)
{
WARN_ON_ONCE(!work_pending(work));
- atomic_long_set(&work->data, data | flags | work_static(work));
+ atomic_long_set(&work->data, data | work_static(work));
}
static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq,
- unsigned long extra_flags)
+ unsigned long flags)
{
- set_work_data(work, (unsigned long)pwq,
- WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags);
+ set_work_data(work, (unsigned long)pwq | WORK_STRUCT_PENDING |
+ WORK_STRUCT_PWQ | flags);
}
static void set_work_pool_and_keep_pending(struct work_struct *work,
- int pool_id)
+ int pool_id, unsigned long flags)
{
- set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT,
- WORK_STRUCT_PENDING);
+ set_work_data(work, ((unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT) |
+ WORK_STRUCT_PENDING | flags);
}
static void set_work_pool_and_clear_pending(struct work_struct *work,
- int pool_id)
+ int pool_id, unsigned long flags)
{
/*
* The following wmb is paired with the implied mb in
* owner.
*/
smp_wmb();
- set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0);
+ set_work_data(work, ((unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT) |
+ flags);
/*
* The following mb guarantees that previous clear of a PENDING bit
* will not be reordered with any speculative LOADS or STORES from
smp_mb();
}
-static void clear_work_data(struct work_struct *work)
+static inline struct pool_workqueue *work_struct_pwq(unsigned long data)
{
- smp_wmb(); /* see set_work_pool_and_clear_pending() */
- set_work_data(work, WORK_STRUCT_NO_POOL, 0);
+ return (struct pool_workqueue *)(data & WORK_STRUCT_PWQ_MASK);
}
static struct pool_workqueue *get_work_pwq(struct work_struct *work)
unsigned long data = atomic_long_read(&work->data);
if (data & WORK_STRUCT_PWQ)
- return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
+ return work_struct_pwq(data);
else
return NULL;
}
assert_rcu_or_pool_mutex();
if (data & WORK_STRUCT_PWQ)
- return ((struct pool_workqueue *)
- (data & WORK_STRUCT_WQ_DATA_MASK))->pool;
+ return work_struct_pwq(data)->pool;
pool_id = data >> WORK_OFFQ_POOL_SHIFT;
if (pool_id == WORK_OFFQ_POOL_NONE)
unsigned long data = atomic_long_read(&work->data);
if (data & WORK_STRUCT_PWQ)
- return ((struct pool_workqueue *)
- (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id;
+ return work_struct_pwq(data)->pool->id;
return data >> WORK_OFFQ_POOL_SHIFT;
}
unsigned long pool_id = get_work_pool_id(work);
pool_id <<= WORK_OFFQ_POOL_SHIFT;
- set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING);
+ set_work_data(work, pool_id | WORK_STRUCT_PENDING | WORK_OFFQ_CANCELING);
}
static bool work_is_canceling(struct work_struct *work)
* they're being called with pool->lock held.
*/
-static bool __need_more_worker(struct worker_pool *pool)
-{
- return !atomic_read(&pool->nr_running);
-}
-
/*
* Need to wake up a worker? Called from anything but currently
* running workers.
*/
static bool need_more_worker(struct worker_pool *pool)
{
- return !list_empty(&pool->worklist) && __need_more_worker(pool);
+ return !list_empty(&pool->worklist) && !pool->nr_running;
}
/* Can I start working? Called from busy but !running workers. */
/* Do I need to keep working? Called from currently running workers. */
static bool keep_working(struct worker_pool *pool)
{
- return !list_empty(&pool->worklist) &&
- atomic_read(&pool->nr_running) <= 1;
+ return !list_empty(&pool->worklist) && (pool->nr_running <= 1);
}
/* Do we need a new worker? Called from manager. */
return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
}
-/*
- * Wake up functions.
- */
-
-/* Return the first idle worker. Safe with preemption disabled */
-static struct worker *first_idle_worker(struct worker_pool *pool)
-{
- if (unlikely(list_empty(&pool->idle_list)))
- return NULL;
-
- return list_first_entry(&pool->idle_list, struct worker, entry);
-}
-
-/**
- * wake_up_worker - wake up an idle worker
- * @pool: worker pool to wake worker from
- *
- * Wake up the first idle worker of @pool.
- *
- * CONTEXT:
- * spin_lock_irq(pool->lock).
- */
-static void wake_up_worker(struct worker_pool *pool)
-{
- struct worker *worker = first_idle_worker(pool);
-
- if (likely(worker))
- wake_up_process(worker->task);
-}
-
-/**
- * wq_worker_running - a worker is running again
- * @task: task waking up
- *
- * This function is called when a worker returns from schedule()
- */
-void wq_worker_running(struct task_struct *task)
-{
- struct worker *worker = kthread_data(task);
-
- if (!worker->sleeping)
- return;
- if (!(worker->flags & WORKER_NOT_RUNNING))
- atomic_inc(&worker->pool->nr_running);
- worker->sleeping = 0;
-}
-
-/**
- * wq_worker_sleeping - a worker is going to sleep
- * @task: task going to sleep
- *
- * This function is called from schedule() when a busy worker is
- * going to sleep.
- */
-void wq_worker_sleeping(struct task_struct *task)
-{
- struct worker *next, *worker = kthread_data(task);
- struct worker_pool *pool;
-
- /*
- * Rescuers, which may not have all the fields set up like normal
- * workers, also reach here, let's not access anything before
- * checking NOT_RUNNING.
- */
- if (worker->flags & WORKER_NOT_RUNNING)
- return;
-
- pool = worker->pool;
-
- if (WARN_ON_ONCE(worker->sleeping))
- return;
-
- worker->sleeping = 1;
- spin_lock_irq(&pool->lock);
-
- /*
- * The counterpart of the following dec_and_test, implied mb,
- * worklist not empty test sequence is in insert_work().
- * Please read comment there.
- *
- * NOT_RUNNING is clear. This means that we're bound to and
- * running on the local cpu w/ rq lock held and preemption
- * disabled, which in turn means that none else could be
- * manipulating idle_list, so dereferencing idle_list without pool
- * lock is safe.
- */
- if (atomic_dec_and_test(&pool->nr_running) &&
- !list_empty(&pool->worklist)) {
- next = first_idle_worker(pool);
- if (next)
- wake_up_process(next->task);
- }
- spin_unlock_irq(&pool->lock);
-}
-
-/**
- * wq_worker_last_func - retrieve worker's last work function
- * @task: Task to retrieve last work function of.
- *
- * Determine the last function a worker executed. This is called from
- * the scheduler to get a worker's last known identity.
- *
- * CONTEXT:
- * spin_lock_irq(rq->lock)
- *
- * This function is called during schedule() when a kworker is going
- * to sleep. It's used by psi to identify aggregation workers during
- * dequeuing, to allow periodic aggregation to shut-off when that
- * worker is the last task in the system or cgroup to go to sleep.
- *
- * As this function doesn't involve any workqueue-related locking, it
- * only returns stable values when called from inside the scheduler's
- * queuing and dequeuing paths, when @task, which must be a kworker,
- * is guaranteed to not be processing any works.
- *
- * Return:
- * The last work function %current executed as a worker, NULL if it
- * hasn't executed any work yet.
- */
-work_func_t wq_worker_last_func(struct task_struct *task)
-{
- struct worker *worker = kthread_data(task);
-
- return worker->last_func;
-}
-
/**
* worker_set_flags - set worker flags and adjust nr_running accordingly
* @worker: self
* @flags: flags to set
*
* Set @flags in @worker->flags and adjust nr_running accordingly.
- *
- * CONTEXT:
- * spin_lock_irq(pool->lock)
*/
static inline void worker_set_flags(struct worker *worker, unsigned int flags)
{
struct worker_pool *pool = worker->pool;
- WARN_ON_ONCE(worker->task != current);
+ lockdep_assert_held(&pool->lock);
/* If transitioning into NOT_RUNNING, adjust nr_running. */
if ((flags & WORKER_NOT_RUNNING) &&
!(worker->flags & WORKER_NOT_RUNNING)) {
- atomic_dec(&pool->nr_running);
+ pool->nr_running--;
}
worker->flags |= flags;
* @flags: flags to clear
*
* Clear @flags in @worker->flags and adjust nr_running accordingly.
- *
- * CONTEXT:
- * spin_lock_irq(pool->lock)
*/
static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
{
struct worker_pool *pool = worker->pool;
unsigned int oflags = worker->flags;
- WARN_ON_ONCE(worker->task != current);
+ lockdep_assert_held(&pool->lock);
worker->flags &= ~flags;
*/
if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
if (!(worker->flags & WORKER_NOT_RUNNING))
- atomic_inc(&pool->nr_running);
+ pool->nr_running++;
+}
+
+/* Return the first idle worker. Called with pool->lock held. */
+static struct worker *first_idle_worker(struct worker_pool *pool)
+{
+ if (unlikely(list_empty(&pool->idle_list)))
+ return NULL;
+
+ return list_first_entry(&pool->idle_list, struct worker, entry);
+}
+
+/**
+ * worker_enter_idle - enter idle state
+ * @worker: worker which is entering idle state
+ *
+ * @worker is entering idle state. Update stats and idle timer if
+ * necessary.
+ *
+ * LOCKING:
+ * raw_spin_lock_irq(pool->lock).
+ */
+static void worker_enter_idle(struct worker *worker)
+{
+ struct worker_pool *pool = worker->pool;
+
+ if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) ||
+ WARN_ON_ONCE(!list_empty(&worker->entry) &&
+ (worker->hentry.next || worker->hentry.pprev)))
+ return;
+
+ /* can't use worker_set_flags(), also called from create_worker() */
+ worker->flags |= WORKER_IDLE;
+ pool->nr_idle++;
+ worker->last_active = jiffies;
+
+ /* idle_list is LIFO */
+ list_add(&worker->entry, &pool->idle_list);
+
+ if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
+ mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
+
+ /* Sanity check nr_running. */
+ WARN_ON_ONCE(pool->nr_workers == pool->nr_idle && pool->nr_running);
+}
+
+/**
+ * worker_leave_idle - leave idle state
+ * @worker: worker which is leaving idle state
+ *
+ * @worker is leaving idle state. Update stats.
+ *
+ * LOCKING:
+ * raw_spin_lock_irq(pool->lock).
+ */
+static void worker_leave_idle(struct worker *worker)
+{
+ struct worker_pool *pool = worker->pool;
+
+ if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE)))
+ return;
+ worker_clr_flags(worker, WORKER_IDLE);
+ pool->nr_idle--;
+ list_del_init(&worker->entry);
}
/**
* actually occurs, it should be easy to locate the culprit work function.
*
* CONTEXT:
- * spin_lock_irq(pool->lock).
+ * raw_spin_lock_irq(pool->lock).
*
* Return:
* Pointer to worker which is executing @work if found, %NULL
* @head: target list to append @work to
* @nextp: out parameter for nested worklist walking
*
- * Schedule linked works starting from @work to @head. Work series to
- * be scheduled starts at @work and includes any consecutive work with
- * WORK_STRUCT_LINKED set in its predecessor.
- *
- * If @nextp is not NULL, it's updated to point to the next work of
- * the last scheduled work. This allows move_linked_works() to be
- * nested inside outer list_for_each_entry_safe().
+ * Schedule linked works starting from @work to @head. Work series to be
+ * scheduled starts at @work and includes any consecutive work with
+ * WORK_STRUCT_LINKED set in its predecessor. See assign_work() for details on
+ * @nextp.
*
* CONTEXT:
- * spin_lock_irq(pool->lock).
+ * raw_spin_lock_irq(pool->lock).
*/
static void move_linked_works(struct work_struct *work, struct list_head *head,
struct work_struct **nextp)
}
/**
- * get_pwq - get an extra reference on the specified pool_workqueue
- * @pwq: pool_workqueue to get
+ * assign_work - assign a work item and its linked work items to a worker
+ * @work: work to assign
+ * @worker: worker to assign to
+ * @nextp: out parameter for nested worklist walking
*
- * Obtain an extra reference on @pwq. The caller should guarantee that
- * @pwq has positive refcnt and be holding the matching pool->lock.
+ * Assign @work and its linked work items to @worker. If @work is already being
+ * executed by another worker in the same pool, it'll be punted there.
+ *
+ * If @nextp is not NULL, it's updated to point to the next work of the last
+ * scheduled work. This allows assign_work() to be nested inside
+ * list_for_each_entry_safe().
+ *
+ * Returns %true if @work was successfully assigned to @worker. %false if @work
+ * was punted to another worker already executing it.
*/
-static void get_pwq(struct pool_workqueue *pwq)
+static bool assign_work(struct work_struct *work, struct worker *worker,
+ struct work_struct **nextp)
{
- lockdep_assert_held(&pwq->pool->lock);
- WARN_ON_ONCE(pwq->refcnt <= 0);
- pwq->refcnt++;
-}
+ struct worker_pool *pool = worker->pool;
+ struct worker *collision;
-/**
- * put_pwq - put a pool_workqueue reference
- * @pwq: pool_workqueue to put
- *
+ lockdep_assert_held(&pool->lock);
+
+ /*
+ * A single work shouldn't be executed concurrently by multiple workers.
+ * __queue_work() ensures that @work doesn't jump to a different pool
+ * while still running in the previous pool. Here, we should ensure that
+ * @work is not executed concurrently by multiple workers from the same
+ * pool. Check whether anyone is already processing the work. If so,
+ * defer the work to the currently executing one.
+ */
+ collision = find_worker_executing_work(pool, work);
+ if (unlikely(collision)) {
+ move_linked_works(work, &collision->scheduled, nextp);
+ return false;
+ }
+
+ move_linked_works(work, &worker->scheduled, nextp);
+ return true;
+}
+
+static struct irq_work *bh_pool_irq_work(struct worker_pool *pool)
+{
+ int high = pool->attrs->nice == HIGHPRI_NICE_LEVEL ? 1 : 0;
+
+ return &per_cpu(bh_pool_irq_works, pool->cpu)[high];
+}
+
+static void kick_bh_pool(struct worker_pool *pool)
+{
+#ifdef CONFIG_SMP
+ /* see drain_dead_softirq_workfn() for BH_DRAINING */
+ if (unlikely(pool->cpu != smp_processor_id() &&
+ !(pool->flags & POOL_BH_DRAINING))) {
+ irq_work_queue_on(bh_pool_irq_work(pool), pool->cpu);
+ return;
+ }
+#endif
+ if (pool->attrs->nice == HIGHPRI_NICE_LEVEL)
+ raise_softirq_irqoff(HI_SOFTIRQ);
+ else
+ raise_softirq_irqoff(TASKLET_SOFTIRQ);
+}
+
+/**
+ * kick_pool - wake up an idle worker if necessary
+ * @pool: pool to kick
+ *
+ * @pool may have pending work items. Wake up worker if necessary. Returns
+ * whether a worker was woken up.
+ */
+static bool kick_pool(struct worker_pool *pool)
+{
+ struct worker *worker = first_idle_worker(pool);
+ struct task_struct *p;
+
+ lockdep_assert_held(&pool->lock);
+
+ if (!need_more_worker(pool) || !worker)
+ return false;
+
+ if (pool->flags & POOL_BH) {
+ kick_bh_pool(pool);
+ return true;
+ }
+
+ p = worker->task;
+
+#ifdef CONFIG_SMP
+ /*
+ * Idle @worker is about to execute @work and waking up provides an
+ * opportunity to migrate @worker at a lower cost by setting the task's
+ * wake_cpu field. Let's see if we want to move @worker to improve
+ * execution locality.
+ *
+ * We're waking the worker that went idle the latest and there's some
+ * chance that @worker is marked idle but hasn't gone off CPU yet. If
+ * so, setting the wake_cpu won't do anything. As this is a best-effort
+ * optimization and the race window is narrow, let's leave as-is for
+ * now. If this becomes pronounced, we can skip over workers which are
+ * still on cpu when picking an idle worker.
+ *
+ * If @pool has non-strict affinity, @worker might have ended up outside
+ * its affinity scope. Repatriate.
+ */
+ if (!pool->attrs->affn_strict &&
+ !cpumask_test_cpu(p->wake_cpu, pool->attrs->__pod_cpumask)) {
+ struct work_struct *work = list_first_entry(&pool->worklist,
+ struct work_struct, entry);
+ p->wake_cpu = cpumask_any_distribute(pool->attrs->__pod_cpumask);
+ get_work_pwq(work)->stats[PWQ_STAT_REPATRIATED]++;
+ }
+#endif
+ wake_up_process(p);
+ return true;
+}
+
+#ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT
+
+/*
+ * Concurrency-managed per-cpu work items that hog CPU for longer than
+ * wq_cpu_intensive_thresh_us trigger the automatic CPU_INTENSIVE mechanism,
+ * which prevents them from stalling other concurrency-managed work items. If a
+ * work function keeps triggering this mechanism, it's likely that the work item
+ * should be using an unbound workqueue instead.
+ *
+ * wq_cpu_intensive_report() tracks work functions which trigger such conditions
+ * and report them so that they can be examined and converted to use unbound
+ * workqueues as appropriate. To avoid flooding the console, each violating work
+ * function is tracked and reported with exponential backoff.
+ */
+#define WCI_MAX_ENTS 128
+
+struct wci_ent {
+ work_func_t func;
+ atomic64_t cnt;
+ struct hlist_node hash_node;
+};
+
+static struct wci_ent wci_ents[WCI_MAX_ENTS];
+static int wci_nr_ents;
+static DEFINE_RAW_SPINLOCK(wci_lock);
+static DEFINE_HASHTABLE(wci_hash, ilog2(WCI_MAX_ENTS));
+
+static struct wci_ent *wci_find_ent(work_func_t func)
+{
+ struct wci_ent *ent;
+
+ hash_for_each_possible_rcu(wci_hash, ent, hash_node,
+ (unsigned long)func) {
+ if (ent->func == func)
+ return ent;
+ }
+ return NULL;
+}
+
+static void wq_cpu_intensive_report(work_func_t func)
+{
+ struct wci_ent *ent;
+
+restart:
+ ent = wci_find_ent(func);
+ if (ent) {
+ u64 cnt;
+
+ /*
+ * Start reporting from the warning_thresh and back off
+ * exponentially.
+ */
+ cnt = atomic64_inc_return_relaxed(&ent->cnt);
+ if (wq_cpu_intensive_warning_thresh &&
+ cnt >= wq_cpu_intensive_warning_thresh &&
+ is_power_of_2(cnt + 1 - wq_cpu_intensive_warning_thresh))
+ printk_deferred(KERN_WARNING "workqueue: %ps hogged CPU for >%luus %llu times, consider switching to WQ_UNBOUND\n",
+ ent->func, wq_cpu_intensive_thresh_us,
+ atomic64_read(&ent->cnt));
+ return;
+ }
+
+ /*
+ * @func is a new violation. Allocate a new entry for it. If wcn_ents[]
+ * is exhausted, something went really wrong and we probably made enough
+ * noise already.
+ */
+ if (wci_nr_ents >= WCI_MAX_ENTS)
+ return;
+
+ raw_spin_lock(&wci_lock);
+
+ if (wci_nr_ents >= WCI_MAX_ENTS) {
+ raw_spin_unlock(&wci_lock);
+ return;
+ }
+
+ if (wci_find_ent(func)) {
+ raw_spin_unlock(&wci_lock);
+ goto restart;
+ }
+
+ ent = &wci_ents[wci_nr_ents++];
+ ent->func = func;
+ atomic64_set(&ent->cnt, 0);
+ hash_add_rcu(wci_hash, &ent->hash_node, (unsigned long)func);
+
+ raw_spin_unlock(&wci_lock);
+
+ goto restart;
+}
+
+#else /* CONFIG_WQ_CPU_INTENSIVE_REPORT */
+static void wq_cpu_intensive_report(work_func_t func) {}
+#endif /* CONFIG_WQ_CPU_INTENSIVE_REPORT */
+
+/**
+ * wq_worker_running - a worker is running again
+ * @task: task waking up
+ *
+ * This function is called when a worker returns from schedule()
+ */
+void wq_worker_running(struct task_struct *task)
+{
+ struct worker *worker = kthread_data(task);
+
+ if (!READ_ONCE(worker->sleeping))
+ return;
+
+ /*
+ * If preempted by unbind_workers() between the WORKER_NOT_RUNNING check
+ * and the nr_running increment below, we may ruin the nr_running reset
+ * and leave with an unexpected pool->nr_running == 1 on the newly unbound
+ * pool. Protect against such race.
+ */
+ preempt_disable();
+ if (!(worker->flags & WORKER_NOT_RUNNING))
+ worker->pool->nr_running++;
+ preempt_enable();
+
+ /*
+ * CPU intensive auto-detection cares about how long a work item hogged
+ * CPU without sleeping. Reset the starting timestamp on wakeup.
+ */
+ worker->current_at = worker->task->se.sum_exec_runtime;
+
+ WRITE_ONCE(worker->sleeping, 0);
+}
+
+/**
+ * wq_worker_sleeping - a worker is going to sleep
+ * @task: task going to sleep
+ *
+ * This function is called from schedule() when a busy worker is
+ * going to sleep.
+ */
+void wq_worker_sleeping(struct task_struct *task)
+{
+ struct worker *worker = kthread_data(task);
+ struct worker_pool *pool;
+
+ /*
+ * Rescuers, which may not have all the fields set up like normal
+ * workers, also reach here, let's not access anything before
+ * checking NOT_RUNNING.
+ */
+ if (worker->flags & WORKER_NOT_RUNNING)
+ return;
+
+ pool = worker->pool;
+
+ /* Return if preempted before wq_worker_running() was reached */
+ if (READ_ONCE(worker->sleeping))
+ return;
+
+ WRITE_ONCE(worker->sleeping, 1);
+ raw_spin_lock_irq(&pool->lock);
+
+ /*
+ * Recheck in case unbind_workers() preempted us. We don't
+ * want to decrement nr_running after the worker is unbound
+ * and nr_running has been reset.
+ */
+ if (worker->flags & WORKER_NOT_RUNNING) {
+ raw_spin_unlock_irq(&pool->lock);
+ return;
+ }
+
+ pool->nr_running--;
+ if (kick_pool(pool))
+ worker->current_pwq->stats[PWQ_STAT_CM_WAKEUP]++;
+
+ raw_spin_unlock_irq(&pool->lock);
+}
+
+/**
+ * wq_worker_tick - a scheduler tick occurred while a kworker is running
+ * @task: task currently running
+ *
+ * Called from scheduler_tick(). We're in the IRQ context and the current
+ * worker's fields which follow the 'K' locking rule can be accessed safely.
+ */
+void wq_worker_tick(struct task_struct *task)
+{
+ struct worker *worker = kthread_data(task);
+ struct pool_workqueue *pwq = worker->current_pwq;
+ struct worker_pool *pool = worker->pool;
+
+ if (!pwq)
+ return;
+
+ pwq->stats[PWQ_STAT_CPU_TIME] += TICK_USEC;
+
+ if (!wq_cpu_intensive_thresh_us)
+ return;
+
+ /*
+ * If the current worker is concurrency managed and hogged the CPU for
+ * longer than wq_cpu_intensive_thresh_us, it's automatically marked
+ * CPU_INTENSIVE to avoid stalling other concurrency-managed work items.
+ *
+ * Set @worker->sleeping means that @worker is in the process of
+ * switching out voluntarily and won't be contributing to
+ * @pool->nr_running until it wakes up. As wq_worker_sleeping() also
+ * decrements ->nr_running, setting CPU_INTENSIVE here can lead to
+ * double decrements. The task is releasing the CPU anyway. Let's skip.
+ * We probably want to make this prettier in the future.
+ */
+ if ((worker->flags & WORKER_NOT_RUNNING) || READ_ONCE(worker->sleeping) ||
+ worker->task->se.sum_exec_runtime - worker->current_at <
+ wq_cpu_intensive_thresh_us * NSEC_PER_USEC)
+ return;
+
+ raw_spin_lock(&pool->lock);
+
+ worker_set_flags(worker, WORKER_CPU_INTENSIVE);
+ wq_cpu_intensive_report(worker->current_func);
+ pwq->stats[PWQ_STAT_CPU_INTENSIVE]++;
+
+ if (kick_pool(pool))
+ pwq->stats[PWQ_STAT_CM_WAKEUP]++;
+
+ raw_spin_unlock(&pool->lock);
+}
+
+/**
+ * wq_worker_last_func - retrieve worker's last work function
+ * @task: Task to retrieve last work function of.
+ *
+ * Determine the last function a worker executed. This is called from
+ * the scheduler to get a worker's last known identity.
+ *
+ * CONTEXT:
+ * raw_spin_lock_irq(rq->lock)
+ *
+ * This function is called during schedule() when a kworker is going
+ * to sleep. It's used by psi to identify aggregation workers during
+ * dequeuing, to allow periodic aggregation to shut-off when that
+ * worker is the last task in the system or cgroup to go to sleep.
+ *
+ * As this function doesn't involve any workqueue-related locking, it
+ * only returns stable values when called from inside the scheduler's
+ * queuing and dequeuing paths, when @task, which must be a kworker,
+ * is guaranteed to not be processing any works.
+ *
+ * Return:
+ * The last work function %current executed as a worker, NULL if it
+ * hasn't executed any work yet.
+ */
+work_func_t wq_worker_last_func(struct task_struct *task)
+{
+ struct worker *worker = kthread_data(task);
+
+ return worker->last_func;
+}
+
+/**
+ * wq_node_nr_active - Determine wq_node_nr_active to use
+ * @wq: workqueue of interest
+ * @node: NUMA node, can be %NUMA_NO_NODE
+ *
+ * Determine wq_node_nr_active to use for @wq on @node. Returns:
+ *
+ * - %NULL for per-cpu workqueues as they don't need to use shared nr_active.
+ *
+ * - node_nr_active[nr_node_ids] if @node is %NUMA_NO_NODE.
+ *
+ * - Otherwise, node_nr_active[@node].
+ */
+static struct wq_node_nr_active *wq_node_nr_active(struct workqueue_struct *wq,
+ int node)
+{
+ if (!(wq->flags & WQ_UNBOUND))
+ return NULL;
+
+ if (node == NUMA_NO_NODE)
+ node = nr_node_ids;
+
+ return wq->node_nr_active[node];
+}
+
+/**
+ * wq_update_node_max_active - Update per-node max_actives to use
+ * @wq: workqueue to update
+ * @off_cpu: CPU that's going down, -1 if a CPU is not going down
+ *
+ * Update @wq->node_nr_active[]->max. @wq must be unbound. max_active is
+ * distributed among nodes according to the proportions of numbers of online
+ * cpus. The result is always between @wq->min_active and max_active.
+ */
+static void wq_update_node_max_active(struct workqueue_struct *wq, int off_cpu)
+{
+ struct cpumask *effective = unbound_effective_cpumask(wq);
+ int min_active = READ_ONCE(wq->min_active);
+ int max_active = READ_ONCE(wq->max_active);
+ int total_cpus, node;
+
+ lockdep_assert_held(&wq->mutex);
+
+ if (!wq_topo_initialized)
+ return;
+
+ if (off_cpu >= 0 && !cpumask_test_cpu(off_cpu, effective))
+ off_cpu = -1;
+
+ total_cpus = cpumask_weight_and(effective, cpu_online_mask);
+ if (off_cpu >= 0)
+ total_cpus--;
+
+ for_each_node(node) {
+ int node_cpus;
+
+ node_cpus = cpumask_weight_and(effective, cpumask_of_node(node));
+ if (off_cpu >= 0 && cpu_to_node(off_cpu) == node)
+ node_cpus--;
+
+ wq_node_nr_active(wq, node)->max =
+ clamp(DIV_ROUND_UP(max_active * node_cpus, total_cpus),
+ min_active, max_active);
+ }
+
+ wq_node_nr_active(wq, NUMA_NO_NODE)->max = min_active;
+}
+
+/**
+ * get_pwq - get an extra reference on the specified pool_workqueue
+ * @pwq: pool_workqueue to get
+ *
+ * Obtain an extra reference on @pwq. The caller should guarantee that
+ * @pwq has positive refcnt and be holding the matching pool->lock.
+ */
+static void get_pwq(struct pool_workqueue *pwq)
+{
+ lockdep_assert_held(&pwq->pool->lock);
+ WARN_ON_ONCE(pwq->refcnt <= 0);
+ pwq->refcnt++;
+}
+
+/**
+ * put_pwq - put a pool_workqueue reference
+ * @pwq: pool_workqueue to put
+ *
* Drop a reference of @pwq. If its refcnt reaches zero, schedule its
* destruction. The caller should be holding the matching pool->lock.
*/
-static void put_pwq(struct pool_workqueue *pwq)
+static void put_pwq(struct pool_workqueue *pwq)
+{
+ lockdep_assert_held(&pwq->pool->lock);
+ if (likely(--pwq->refcnt))
+ return;
+ /*
+ * @pwq can't be released under pool->lock, bounce to a dedicated
+ * kthread_worker to avoid A-A deadlocks.
+ */
+ kthread_queue_work(pwq_release_worker, &pwq->release_work);
+}
+
+/**
+ * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock
+ * @pwq: pool_workqueue to put (can be %NULL)
+ *
+ * put_pwq() with locking. This function also allows %NULL @pwq.
+ */
+static void put_pwq_unlocked(struct pool_workqueue *pwq)
+{
+ if (pwq) {
+ /*
+ * As both pwqs and pools are RCU protected, the
+ * following lock operations are safe.
+ */
+ raw_spin_lock_irq(&pwq->pool->lock);
+ put_pwq(pwq);
+ raw_spin_unlock_irq(&pwq->pool->lock);
+ }
+}
+
+static bool pwq_is_empty(struct pool_workqueue *pwq)
+{
+ return !pwq->nr_active && list_empty(&pwq->inactive_works);
+}
+
+static void __pwq_activate_work(struct pool_workqueue *pwq,
+ struct work_struct *work)
+{
+ unsigned long *wdb = work_data_bits(work);
+
+ WARN_ON_ONCE(!(*wdb & WORK_STRUCT_INACTIVE));
+ trace_workqueue_activate_work(work);
+ if (list_empty(&pwq->pool->worklist))
+ pwq->pool->watchdog_ts = jiffies;
+ move_linked_works(work, &pwq->pool->worklist, NULL);
+ __clear_bit(WORK_STRUCT_INACTIVE_BIT, wdb);
+}
+
+/**
+ * pwq_activate_work - Activate a work item if inactive
+ * @pwq: pool_workqueue @work belongs to
+ * @work: work item to activate
+ *
+ * Returns %true if activated. %false if already active.
+ */
+static bool pwq_activate_work(struct pool_workqueue *pwq,
+ struct work_struct *work)
+{
+ struct worker_pool *pool = pwq->pool;
+ struct wq_node_nr_active *nna;
+
+ lockdep_assert_held(&pool->lock);
+
+ if (!(*work_data_bits(work) & WORK_STRUCT_INACTIVE))
+ return false;
+
+ nna = wq_node_nr_active(pwq->wq, pool->node);
+ if (nna)
+ atomic_inc(&nna->nr);
+
+ pwq->nr_active++;
+ __pwq_activate_work(pwq, work);
+ return true;
+}
+
+static bool tryinc_node_nr_active(struct wq_node_nr_active *nna)
+{
+ int max = READ_ONCE(nna->max);
+
+ while (true) {
+ int old, tmp;
+
+ old = atomic_read(&nna->nr);
+ if (old >= max)
+ return false;
+ tmp = atomic_cmpxchg_relaxed(&nna->nr, old, old + 1);
+ if (tmp == old)
+ return true;
+ }
+}
+
+/**
+ * pwq_tryinc_nr_active - Try to increment nr_active for a pwq
+ * @pwq: pool_workqueue of interest
+ * @fill: max_active may have increased, try to increase concurrency level
+ *
+ * Try to increment nr_active for @pwq. Returns %true if an nr_active count is
+ * successfully obtained. %false otherwise.
+ */
+static bool pwq_tryinc_nr_active(struct pool_workqueue *pwq, bool fill)
+{
+ struct workqueue_struct *wq = pwq->wq;
+ struct worker_pool *pool = pwq->pool;
+ struct wq_node_nr_active *nna = wq_node_nr_active(wq, pool->node);
+ bool obtained = false;
+
+ lockdep_assert_held(&pool->lock);
+
+ if (!nna) {
+ /* BH or per-cpu workqueue, pwq->nr_active is sufficient */
+ obtained = pwq->nr_active < READ_ONCE(wq->max_active);
+ goto out;
+ }
+
+ if (unlikely(pwq->plugged))
+ return false;
+
+ /*
+ * Unbound workqueue uses per-node shared nr_active $nna. If @pwq is
+ * already waiting on $nna, pwq_dec_nr_active() will maintain the
+ * concurrency level. Don't jump the line.
+ *
+ * We need to ignore the pending test after max_active has increased as
+ * pwq_dec_nr_active() can only maintain the concurrency level but not
+ * increase it. This is indicated by @fill.
+ */
+ if (!list_empty(&pwq->pending_node) && likely(!fill))
+ goto out;
+
+ obtained = tryinc_node_nr_active(nna);
+ if (obtained)
+ goto out;
+
+ /*
+ * Lockless acquisition failed. Lock, add ourself to $nna->pending_pwqs
+ * and try again. The smp_mb() is paired with the implied memory barrier
+ * of atomic_dec_return() in pwq_dec_nr_active() to ensure that either
+ * we see the decremented $nna->nr or they see non-empty
+ * $nna->pending_pwqs.
+ */
+ raw_spin_lock(&nna->lock);
+
+ if (list_empty(&pwq->pending_node))
+ list_add_tail(&pwq->pending_node, &nna->pending_pwqs);
+ else if (likely(!fill))
+ goto out_unlock;
+
+ smp_mb();
+
+ obtained = tryinc_node_nr_active(nna);
+
+ /*
+ * If @fill, @pwq might have already been pending. Being spuriously
+ * pending in cold paths doesn't affect anything. Let's leave it be.
+ */
+ if (obtained && likely(!fill))
+ list_del_init(&pwq->pending_node);
+
+out_unlock:
+ raw_spin_unlock(&nna->lock);
+out:
+ if (obtained)
+ pwq->nr_active++;
+ return obtained;
+}
+
+/**
+ * pwq_activate_first_inactive - Activate the first inactive work item on a pwq
+ * @pwq: pool_workqueue of interest
+ * @fill: max_active may have increased, try to increase concurrency level
+ *
+ * Activate the first inactive work item of @pwq if available and allowed by
+ * max_active limit.
+ *
+ * Returns %true if an inactive work item has been activated. %false if no
+ * inactive work item is found or max_active limit is reached.
+ */
+static bool pwq_activate_first_inactive(struct pool_workqueue *pwq, bool fill)
+{
+ struct work_struct *work =
+ list_first_entry_or_null(&pwq->inactive_works,
+ struct work_struct, entry);
+
+ if (work && pwq_tryinc_nr_active(pwq, fill)) {
+ __pwq_activate_work(pwq, work);
+ return true;
+ } else {
+ return false;
+ }
+}
+
+/**
+ * unplug_oldest_pwq - unplug the oldest pool_workqueue
+ * @wq: workqueue_struct where its oldest pwq is to be unplugged
+ *
+ * This function should only be called for ordered workqueues where only the
+ * oldest pwq is unplugged, the others are plugged to suspend execution to
+ * ensure proper work item ordering::
+ *
+ * dfl_pwq --------------+ [P] - plugged
+ * |
+ * v
+ * pwqs -> A -> B [P] -> C [P] (newest)
+ * | | |
+ * 1 3 5
+ * | | |
+ * 2 4 6
+ *
+ * When the oldest pwq is drained and removed, this function should be called
+ * to unplug the next oldest one to start its work item execution. Note that
+ * pwq's are linked into wq->pwqs with the oldest first, so the first one in
+ * the list is the oldest.
+ */
+static void unplug_oldest_pwq(struct workqueue_struct *wq)
{
- lockdep_assert_held(&pwq->pool->lock);
- if (likely(--pwq->refcnt))
- return;
- if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND)))
- return;
- /*
- * @pwq can't be released under pool->lock, bounce to
- * pwq_unbound_release_workfn(). This never recurses on the same
- * pool->lock as this path is taken only for unbound workqueues and
- * the release work item is scheduled on a per-cpu workqueue. To
- * avoid lockdep warning, unbound pool->locks are given lockdep
- * subclass of 1 in get_unbound_pool().
- */
- schedule_work(&pwq->unbound_release_work);
+ struct pool_workqueue *pwq;
+
+ lockdep_assert_held(&wq->mutex);
+
+ /* Caller should make sure that pwqs isn't empty before calling */
+ pwq = list_first_entry_or_null(&wq->pwqs, struct pool_workqueue,
+ pwqs_node);
+ raw_spin_lock_irq(&pwq->pool->lock);
+ if (pwq->plugged) {
+ pwq->plugged = false;
+ if (pwq_activate_first_inactive(pwq, true))
+ kick_pool(pwq->pool);
+ }
+ raw_spin_unlock_irq(&pwq->pool->lock);
}
/**
- * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock
- * @pwq: pool_workqueue to put (can be %NULL)
+ * node_activate_pending_pwq - Activate a pending pwq on a wq_node_nr_active
+ * @nna: wq_node_nr_active to activate a pending pwq for
+ * @caller_pool: worker_pool the caller is locking
*
- * put_pwq() with locking. This function also allows %NULL @pwq.
+ * Activate a pwq in @nna->pending_pwqs. Called with @caller_pool locked.
+ * @caller_pool may be unlocked and relocked to lock other worker_pools.
*/
-static void put_pwq_unlocked(struct pool_workqueue *pwq)
+static void node_activate_pending_pwq(struct wq_node_nr_active *nna,
+ struct worker_pool *caller_pool)
{
- if (pwq) {
- /*
- * As both pwqs and pools are RCU protected, the
- * following lock operations are safe.
- */
- spin_lock_irq(&pwq->pool->lock);
- put_pwq(pwq);
- spin_unlock_irq(&pwq->pool->lock);
+ struct worker_pool *locked_pool = caller_pool;
+ struct pool_workqueue *pwq;
+ struct work_struct *work;
+
+ lockdep_assert_held(&caller_pool->lock);
+
+ raw_spin_lock(&nna->lock);
+retry:
+ pwq = list_first_entry_or_null(&nna->pending_pwqs,
+ struct pool_workqueue, pending_node);
+ if (!pwq)
+ goto out_unlock;
+
+ /*
+ * If @pwq is for a different pool than @locked_pool, we need to lock
+ * @pwq->pool->lock. Let's trylock first. If unsuccessful, do the unlock
+ * / lock dance. For that, we also need to release @nna->lock as it's
+ * nested inside pool locks.
+ */
+ if (pwq->pool != locked_pool) {
+ raw_spin_unlock(&locked_pool->lock);
+ locked_pool = pwq->pool;
+ if (!raw_spin_trylock(&locked_pool->lock)) {
+ raw_spin_unlock(&nna->lock);
+ raw_spin_lock(&locked_pool->lock);
+ raw_spin_lock(&nna->lock);
+ goto retry;
+ }
}
-}
-static void pwq_activate_delayed_work(struct work_struct *work)
-{
- struct pool_workqueue *pwq = get_work_pwq(work);
+ /*
+ * $pwq may not have any inactive work items due to e.g. cancellations.
+ * Drop it from pending_pwqs and see if there's another one.
+ */
+ work = list_first_entry_or_null(&pwq->inactive_works,
+ struct work_struct, entry);
+ if (!work) {
+ list_del_init(&pwq->pending_node);
+ goto retry;
+ }
- trace_workqueue_activate_work(work);
- if (list_empty(&pwq->pool->worklist))
- pwq->pool->watchdog_ts = jiffies;
- move_linked_works(work, &pwq->pool->worklist, NULL);
- __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
- pwq->nr_active++;
+ /*
+ * Acquire an nr_active count and activate the inactive work item. If
+ * $pwq still has inactive work items, rotate it to the end of the
+ * pending_pwqs so that we round-robin through them. This means that
+ * inactive work items are not activated in queueing order which is fine
+ * given that there has never been any ordering across different pwqs.
+ */
+ if (likely(tryinc_node_nr_active(nna))) {
+ pwq->nr_active++;
+ __pwq_activate_work(pwq, work);
+
+ if (list_empty(&pwq->inactive_works))
+ list_del_init(&pwq->pending_node);
+ else
+ list_move_tail(&pwq->pending_node, &nna->pending_pwqs);
+
+ /* if activating a foreign pool, make sure it's running */
+ if (pwq->pool != caller_pool)
+ kick_pool(pwq->pool);
+ }
+
+out_unlock:
+ raw_spin_unlock(&nna->lock);
+ if (locked_pool != caller_pool) {
+ raw_spin_unlock(&locked_pool->lock);
+ raw_spin_lock(&caller_pool->lock);
+ }
}
-static void pwq_activate_first_delayed(struct pool_workqueue *pwq)
+/**
+ * pwq_dec_nr_active - Retire an active count
+ * @pwq: pool_workqueue of interest
+ *
+ * Decrement @pwq's nr_active and try to activate the first inactive work item.
+ * For unbound workqueues, this function may temporarily drop @pwq->pool->lock.
+ */
+static void pwq_dec_nr_active(struct pool_workqueue *pwq)
{
- struct work_struct *work = list_first_entry(&pwq->delayed_works,
- struct work_struct, entry);
+ struct worker_pool *pool = pwq->pool;
+ struct wq_node_nr_active *nna = wq_node_nr_active(pwq->wq, pool->node);
+
+ lockdep_assert_held(&pool->lock);
+
+ /*
+ * @pwq->nr_active should be decremented for both percpu and unbound
+ * workqueues.
+ */
+ pwq->nr_active--;
+
+ /*
+ * For a percpu workqueue, it's simple. Just need to kick the first
+ * inactive work item on @pwq itself.
+ */
+ if (!nna) {
+ pwq_activate_first_inactive(pwq, false);
+ return;
+ }
+
+ /*
+ * If @pwq is for an unbound workqueue, it's more complicated because
+ * multiple pwqs and pools may be sharing the nr_active count. When a
+ * pwq needs to wait for an nr_active count, it puts itself on
+ * $nna->pending_pwqs. The following atomic_dec_return()'s implied
+ * memory barrier is paired with smp_mb() in pwq_tryinc_nr_active() to
+ * guarantee that either we see non-empty pending_pwqs or they see
+ * decremented $nna->nr.
+ *
+ * $nna->max may change as CPUs come online/offline and @pwq->wq's
+ * max_active gets updated. However, it is guaranteed to be equal to or
+ * larger than @pwq->wq->min_active which is above zero unless freezing.
+ * This maintains the forward progress guarantee.
+ */
+ if (atomic_dec_return(&nna->nr) >= READ_ONCE(nna->max))
+ return;
- pwq_activate_delayed_work(work);
+ if (!list_empty(&nna->pending_pwqs))
+ node_activate_pending_pwq(nna, pool);
}
/**
* pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
* @pwq: pwq of interest
- * @color: color of work which left the queue
+ * @work_data: work_data of work which left the queue
*
* A work either has completed or is removed from pending queue,
* decrement nr_in_flight of its pwq and handle workqueue flushing.
*
+ * NOTE:
+ * For unbound workqueues, this function may temporarily drop @pwq->pool->lock
+ * and thus should be called after all other state updates for the in-flight
+ * work item is complete.
+ *
* CONTEXT:
- * spin_lock_irq(pool->lock).
+ * raw_spin_lock_irq(pool->lock).
*/
-static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color)
+static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, unsigned long work_data)
{
- /* uncolored work items don't participate in flushing or nr_active */
- if (color == WORK_NO_COLOR)
- goto out_put;
+ int color = get_work_color(work_data);
- pwq->nr_in_flight[color]--;
+ if (!(work_data & WORK_STRUCT_INACTIVE))
+ pwq_dec_nr_active(pwq);
- pwq->nr_active--;
- if (!list_empty(&pwq->delayed_works)) {
- /* one down, submit a delayed one */
- if (pwq->nr_active < pwq->max_active)
- pwq_activate_first_delayed(pwq);
- }
+ pwq->nr_in_flight[color]--;
/* is flush in progress and are we at the flushing tip? */
if (likely(pwq->flush_color != color))
/**
* try_to_grab_pending - steal work item from worklist and disable irq
* @work: work item to steal
- * @is_dwork: @work is a delayed_work
- * @flags: place to store irq state
+ * @cflags: %WORK_CANCEL_ flags
+ * @irq_flags: place to store irq state
*
* Try to grab PENDING bit of @work. This function can handle @work in any
* stable state - idle, on timer or on worklist.
*
* Return:
+ *
+ * ======== ================================================================
* 1 if @work was pending and we successfully stole PENDING
* 0 if @work was idle and we claimed PENDING
* -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry
* -ENOENT if someone else is canceling @work, this state may persist
* for arbitrarily long
+ * ======== ================================================================
*
* Note:
* On >= 0 return, the caller owns @work's PENDING bit. To avoid getting
* irqsafe, ensures that we return -EAGAIN for finite short period of time.
*
* On successful return, >= 0, irq is disabled and the caller is
- * responsible for releasing it using local_irq_restore(*@flags).
+ * responsible for releasing it using local_irq_restore(*@irq_flags).
*
* This function is safe to call from any context including IRQ handler.
*/
-static int try_to_grab_pending(struct work_struct *work, bool is_dwork,
- unsigned long *flags)
+static int try_to_grab_pending(struct work_struct *work, u32 cflags,
+ unsigned long *irq_flags)
{
struct worker_pool *pool;
struct pool_workqueue *pwq;
- local_irq_save(*flags);
+ local_irq_save(*irq_flags);
/* try to steal the timer if it exists */
- if (is_dwork) {
+ if (cflags & WORK_CANCEL_DELAYED) {
struct delayed_work *dwork = to_delayed_work(work);
/*
if (!pool)
goto fail;
- spin_lock(&pool->lock);
+ raw_spin_lock(&pool->lock);
/*
* work->data is guaranteed to point to pwq only while the work
* item is queued on pwq->wq, and both updating work->data to point
*/
pwq = get_work_pwq(work);
if (pwq && pwq->pool == pool) {
+ unsigned long work_data;
+
debug_work_deactivate(work);
/*
- * A delayed work item cannot be grabbed directly because
- * it might have linked NO_COLOR work items which, if left
- * on the delayed_list, will confuse pwq->nr_active
+ * A cancelable inactive work item must be in the
+ * pwq->inactive_works since a queued barrier can't be
+ * canceled (see the comments in insert_wq_barrier()).
+ *
+ * An inactive work item cannot be grabbed directly because
+ * it might have linked barrier work items which, if left
+ * on the inactive_works list, will confuse pwq->nr_active
* management later on and cause stall. Make sure the work
* item is activated before grabbing.
*/
- if (*work_data_bits(work) & WORK_STRUCT_DELAYED)
- pwq_activate_delayed_work(work);
+ pwq_activate_work(pwq, work);
list_del_init(&work->entry);
- pwq_dec_nr_in_flight(pwq, get_work_color(work));
- /* work->data points to pwq iff queued, point to pool */
- set_work_pool_and_keep_pending(work, pool->id);
+ /*
+ * work->data points to pwq iff queued. Let's point to pool. As
+ * this destroys work->data needed by the next step, stash it.
+ */
+ work_data = *work_data_bits(work);
+ set_work_pool_and_keep_pending(work, pool->id, 0);
+
+ /* must be the last step, see the function comment */
+ pwq_dec_nr_in_flight(pwq, work_data);
- spin_unlock(&pool->lock);
+ raw_spin_unlock(&pool->lock);
rcu_read_unlock();
return 1;
}
- spin_unlock(&pool->lock);
+ raw_spin_unlock(&pool->lock);
fail:
rcu_read_unlock();
- local_irq_restore(*flags);
+ local_irq_restore(*irq_flags);
if (work_is_canceling(work))
return -ENOENT;
cpu_relax();
return -EAGAIN;
}
+struct cwt_wait {
+ wait_queue_entry_t wait;
+ struct work_struct *work;
+};
+
+static int cwt_wakefn(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
+{
+ struct cwt_wait *cwait = container_of(wait, struct cwt_wait, wait);
+
+ if (cwait->work != key)
+ return 0;
+ return autoremove_wake_function(wait, mode, sync, key);
+}
+
+/**
+ * work_grab_pending - steal work item from worklist and disable irq
+ * @work: work item to steal
+ * @cflags: %WORK_CANCEL_ flags
+ * @irq_flags: place to store IRQ state
+ *
+ * Grab PENDING bit of @work. @work can be in any stable state - idle, on timer
+ * or on worklist.
+ *
+ * Must be called in process context. IRQ is disabled on return with IRQ state
+ * stored in *@irq_flags. The caller is responsible for re-enabling it using
+ * local_irq_restore().
+ *
+ * Returns %true if @work was pending. %false if idle.
+ */
+static bool work_grab_pending(struct work_struct *work, u32 cflags,
+ unsigned long *irq_flags)
+{
+ struct cwt_wait cwait;
+ int ret;
+
+ might_sleep();
+repeat:
+ ret = try_to_grab_pending(work, cflags, irq_flags);
+ if (likely(ret >= 0))
+ return ret;
+ if (ret != -ENOENT)
+ goto repeat;
+
+ /*
+ * Someone is already canceling. Wait for it to finish. flush_work()
+ * doesn't work for PREEMPT_NONE because we may get woken up between
+ * @work's completion and the other canceling task resuming and clearing
+ * CANCELING - flush_work() will return false immediately as @work is no
+ * longer busy, try_to_grab_pending() will return -ENOENT as @work is
+ * still being canceled and the other canceling task won't be able to
+ * clear CANCELING as we're hogging the CPU.
+ *
+ * Let's wait for completion using a waitqueue. As this may lead to the
+ * thundering herd problem, use a custom wake function which matches
+ * @work along with exclusive wait and wakeup.
+ */
+ init_wait(&cwait.wait);
+ cwait.wait.func = cwt_wakefn;
+ cwait.work = work;
+
+ prepare_to_wait_exclusive(&wq_cancel_waitq, &cwait.wait,
+ TASK_UNINTERRUPTIBLE);
+ if (work_is_canceling(work))
+ schedule();
+ finish_wait(&wq_cancel_waitq, &cwait.wait);
+
+ goto repeat;
+}
+
/**
* insert_work - insert a work into a pool
* @pwq: pwq @work belongs to
* work_struct flags.
*
* CONTEXT:
- * spin_lock_irq(pool->lock).
+ * raw_spin_lock_irq(pool->lock).
*/
static void insert_work(struct pool_workqueue *pwq, struct work_struct *work,
struct list_head *head, unsigned int extra_flags)
{
- struct worker_pool *pool = pwq->pool;
+ debug_work_activate(work);
+
+ /* record the work call stack in order to print it in KASAN reports */
+ kasan_record_aux_stack_noalloc(work);
/* we own @work, set data and link */
set_work_pwq(work, pwq, extra_flags);
list_add_tail(&work->entry, head);
get_pwq(pwq);
-
- /*
- * Ensure either wq_worker_sleeping() sees the above
- * list_add_tail() or we see zero nr_running to avoid workers lying
- * around lazily while there are works to be processed.
- */
- smp_mb();
-
- if (__need_more_worker(pool))
- wake_up_worker(pool);
}
/*
*/
static int wq_select_unbound_cpu(int cpu)
{
- static bool printed_dbg_warning;
int new_cpu;
if (likely(!wq_debug_force_rr_cpu)) {
if (cpumask_test_cpu(cpu, wq_unbound_cpumask))
return cpu;
- } else if (!printed_dbg_warning) {
- pr_warn("workqueue: round-robin CPU selection forced, expect performance impact\n");
- printed_dbg_warning = true;
+ } else {
+ pr_warn_once("workqueue: round-robin CPU selection forced, expect performance impact\n");
}
- if (cpumask_empty(wq_unbound_cpumask))
- return cpu;
-
new_cpu = __this_cpu_read(wq_rr_cpu_last);
new_cpu = cpumask_next_and(new_cpu, wq_unbound_cpumask, cpu_online_mask);
if (unlikely(new_cpu >= nr_cpu_ids)) {
struct work_struct *work)
{
struct pool_workqueue *pwq;
- struct worker_pool *last_pool;
- struct list_head *worklist;
+ struct worker_pool *last_pool, *pool;
unsigned int work_flags;
unsigned int req_cpu = cpu;
*/
lockdep_assert_irqs_disabled();
- debug_work_activate(work);
-
- /* if draining, only works from the same workqueue are allowed */
- if (unlikely(wq->flags & __WQ_DRAINING) &&
- WARN_ON_ONCE(!is_chained_work(wq)))
+ /*
+ * For a draining wq, only works from the same workqueue are
+ * allowed. The __WQ_DESTROYING helps to spot the issue that
+ * queues a new work item to a wq after destroy_workqueue(wq).
+ */
+ if (unlikely(wq->flags & (__WQ_DESTROYING | __WQ_DRAINING) &&
+ WARN_ON_ONCE(!is_chained_work(wq))))
return;
rcu_read_lock();
retry:
- if (req_cpu == WORK_CPU_UNBOUND)
- cpu = wq_select_unbound_cpu(raw_smp_processor_id());
-
/* pwq which will be used unless @work is executing elsewhere */
- if (!(wq->flags & WQ_UNBOUND))
- pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
- else
- pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
+ if (req_cpu == WORK_CPU_UNBOUND) {
+ if (wq->flags & WQ_UNBOUND)
+ cpu = wq_select_unbound_cpu(raw_smp_processor_id());
+ else
+ cpu = raw_smp_processor_id();
+ }
+
+ pwq = rcu_dereference(*per_cpu_ptr(wq->cpu_pwq, cpu));
+ pool = pwq->pool;
/*
* If @work was previously on a different pool, it might still be
* pool to guarantee non-reentrancy.
*/
last_pool = get_work_pool(work);
- if (last_pool && last_pool != pwq->pool) {
+ if (last_pool && last_pool != pool) {
struct worker *worker;
- spin_lock(&last_pool->lock);
+ raw_spin_lock(&last_pool->lock);
worker = find_worker_executing_work(last_pool, work);
if (worker && worker->current_pwq->wq == wq) {
pwq = worker->current_pwq;
+ pool = pwq->pool;
+ WARN_ON_ONCE(pool != last_pool);
} else {
/* meh... not running there, queue here */
- spin_unlock(&last_pool->lock);
- spin_lock(&pwq->pool->lock);
+ raw_spin_unlock(&last_pool->lock);
+ raw_spin_lock(&pool->lock);
}
} else {
- spin_lock(&pwq->pool->lock);
+ raw_spin_lock(&pool->lock);
}
/*
- * pwq is determined and locked. For unbound pools, we could have
- * raced with pwq release and it could already be dead. If its
- * refcnt is zero, repeat pwq selection. Note that pwqs never die
- * without another pwq replacing it in the numa_pwq_tbl or while
- * work items are executing on it, so the retrying is guaranteed to
- * make forward-progress.
+ * pwq is determined and locked. For unbound pools, we could have raced
+ * with pwq release and it could already be dead. If its refcnt is zero,
+ * repeat pwq selection. Note that unbound pwqs never die without
+ * another pwq replacing it in cpu_pwq or while work items are executing
+ * on it, so the retrying is guaranteed to make forward-progress.
*/
if (unlikely(!pwq->refcnt)) {
if (wq->flags & WQ_UNBOUND) {
- spin_unlock(&pwq->pool->lock);
+ raw_spin_unlock(&pool->lock);
cpu_relax();
goto retry;
}
pwq->nr_in_flight[pwq->work_color]++;
work_flags = work_color_to_flags(pwq->work_color);
- if (likely(pwq->nr_active < pwq->max_active)) {
+ /*
+ * Limit the number of concurrently active work items to max_active.
+ * @work must also queue behind existing inactive work items to maintain
+ * ordering when max_active changes. See wq_adjust_max_active().
+ */
+ if (list_empty(&pwq->inactive_works) && pwq_tryinc_nr_active(pwq, false)) {
+ if (list_empty(&pool->worklist))
+ pool->watchdog_ts = jiffies;
+
trace_workqueue_activate_work(work);
- pwq->nr_active++;
- worklist = &pwq->pool->worklist;
- if (list_empty(worklist))
- pwq->pool->watchdog_ts = jiffies;
+ insert_work(pwq, work, &pool->worklist, work_flags);
+ kick_pool(pool);
} else {
- work_flags |= WORK_STRUCT_DELAYED;
- worklist = &pwq->delayed_works;
+ work_flags |= WORK_STRUCT_INACTIVE;
+ insert_work(pwq, work, &pwq->inactive_works, work_flags);
}
- insert_work(pwq, work, worklist, work_flags);
-
out:
- spin_unlock(&pwq->pool->lock);
+ raw_spin_unlock(&pool->lock);
rcu_read_unlock();
}
* @work: work to queue
*
* We queue the work to a specific CPU, the caller must ensure it
- * can't go away.
+ * can't go away. Callers that fail to ensure that the specified
+ * CPU cannot go away will execute on a randomly chosen CPU.
+ * But note well that callers specifying a CPU that never has been
+ * online will get a splat.
*
* Return: %false if @work was already on a queue, %true otherwise.
*/
struct work_struct *work)
{
bool ret = false;
- unsigned long flags;
+ unsigned long irq_flags;
- local_irq_save(flags);
+ local_irq_save(irq_flags);
if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
__queue_work(cpu, wq, work);
ret = true;
}
- local_irq_restore(flags);
+ local_irq_restore(irq_flags);
return ret;
}
EXPORT_SYMBOL(queue_work_on);
/**
- * workqueue_select_cpu_near - Select a CPU based on NUMA node
+ * select_numa_node_cpu - Select a CPU based on NUMA node
* @node: NUMA node ID that we want to select a CPU from
*
* This function will attempt to find a "random" cpu available on a given
* WORK_CPU_UNBOUND indicating that we should just schedule to any
* available CPU if we need to schedule this work.
*/
-static int workqueue_select_cpu_near(int node)
+static int select_numa_node_cpu(int node)
{
int cpu;
- /* No point in doing this if NUMA isn't enabled for workqueues */
- if (!wq_numa_enabled)
- return WORK_CPU_UNBOUND;
-
/* Delay binding to CPU if node is not valid or online */
if (node < 0 || node >= MAX_NUMNODES || !node_online(node))
return WORK_CPU_UNBOUND;
bool queue_work_node(int node, struct workqueue_struct *wq,
struct work_struct *work)
{
- unsigned long flags;
+ unsigned long irq_flags;
bool ret = false;
/*
*/
WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND));
- local_irq_save(flags);
+ local_irq_save(irq_flags);
if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
- int cpu = workqueue_select_cpu_near(node);
+ int cpu = select_numa_node_cpu(node);
__queue_work(cpu, wq, work);
ret = true;
}
- local_irq_restore(flags);
+ local_irq_restore(irq_flags);
return ret;
}
EXPORT_SYMBOL_GPL(queue_work_node);
dwork->cpu = cpu;
timer->expires = jiffies + delay;
- if (unlikely(cpu != WORK_CPU_UNBOUND))
+ if (housekeeping_enabled(HK_TYPE_TIMER)) {
+ /* If the current cpu is a housekeeping cpu, use it. */
+ cpu = smp_processor_id();
+ if (!housekeeping_test_cpu(cpu, HK_TYPE_TIMER))
+ cpu = housekeeping_any_cpu(HK_TYPE_TIMER);
add_timer_on(timer, cpu);
- else
- add_timer(timer);
+ } else {
+ if (likely(cpu == WORK_CPU_UNBOUND))
+ add_timer_global(timer);
+ else
+ add_timer_on(timer, cpu);
+ }
}
/**
{
struct work_struct *work = &dwork->work;
bool ret = false;
- unsigned long flags;
+ unsigned long irq_flags;
/* read the comment in __queue_work() */
- local_irq_save(flags);
+ local_irq_save(irq_flags);
if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
__queue_delayed_work(cpu, wq, dwork, delay);
ret = true;
}
- local_irq_restore(flags);
+ local_irq_restore(irq_flags);
return ret;
}
EXPORT_SYMBOL(queue_delayed_work_on);
bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
struct delayed_work *dwork, unsigned long delay)
{
- unsigned long flags;
+ unsigned long irq_flags;
int ret;
do {
- ret = try_to_grab_pending(&dwork->work, true, &flags);
+ ret = try_to_grab_pending(&dwork->work, WORK_CANCEL_DELAYED,
+ &irq_flags);
} while (unlikely(ret == -EAGAIN));
if (likely(ret >= 0)) {
__queue_delayed_work(cpu, wq, dwork, delay);
- local_irq_restore(flags);
+ local_irq_restore(irq_flags);
}
/* -ENOENT from try_to_grab_pending() becomes %true */
if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
rwork->wq = wq;
- call_rcu(&rwork->rcu, rcu_work_rcufn);
+ call_rcu_hurry(&rwork->rcu, rcu_work_rcufn);
return true;
}
}
EXPORT_SYMBOL(queue_rcu_work);
-/**
- * worker_enter_idle - enter idle state
- * @worker: worker which is entering idle state
- *
- * @worker is entering idle state. Update stats and idle timer if
- * necessary.
- *
- * LOCKING:
- * spin_lock_irq(pool->lock).
- */
-static void worker_enter_idle(struct worker *worker)
-{
- struct worker_pool *pool = worker->pool;
-
- if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) ||
- WARN_ON_ONCE(!list_empty(&worker->entry) &&
- (worker->hentry.next || worker->hentry.pprev)))
- return;
-
- /* can't use worker_set_flags(), also called from create_worker() */
- worker->flags |= WORKER_IDLE;
- pool->nr_idle++;
- worker->last_active = jiffies;
-
- /* idle_list is LIFO */
- list_add(&worker->entry, &pool->idle_list);
-
- if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
- mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
-
- /*
- * Sanity check nr_running. Because unbind_workers() releases
- * pool->lock between setting %WORKER_UNBOUND and zapping
- * nr_running, the warning may trigger spuriously. Check iff
- * unbind is not in progress.
- */
- WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
- pool->nr_workers == pool->nr_idle &&
- atomic_read(&pool->nr_running));
-}
-
-/**
- * worker_leave_idle - leave idle state
- * @worker: worker which is leaving idle state
- *
- * @worker is leaving idle state. Update stats.
- *
- * LOCKING:
- * spin_lock_irq(pool->lock).
- */
-static void worker_leave_idle(struct worker *worker)
-{
- struct worker_pool *pool = worker->pool;
-
- if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE)))
- return;
- worker_clr_flags(worker, WORKER_IDLE);
- pool->nr_idle--;
- list_del_init(&worker->entry);
-}
-
static struct worker *alloc_worker(int node)
{
struct worker *worker;
return worker;
}
+static cpumask_t *pool_allowed_cpus(struct worker_pool *pool)
+{
+ if (pool->cpu < 0 && pool->attrs->affn_strict)
+ return pool->attrs->__pod_cpumask;
+ else
+ return pool->attrs->cpumask;
+}
+
/**
* worker_attach_to_pool() - attach a worker to a pool
* @worker: worker to be attached
* cpu-[un]hotplugs.
*/
static void worker_attach_to_pool(struct worker *worker,
- struct worker_pool *pool)
+ struct worker_pool *pool)
{
mutex_lock(&wq_pool_attach_mutex);
/*
- * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
- * online CPUs. It'll be re-applied when any of the CPUs come up.
- */
- set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask);
-
- /*
- * The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains
- * stable across this function. See the comments above the flag
- * definition for details.
+ * The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains stable
+ * across this function. See the comments above the flag definition for
+ * details. BH workers are, while per-CPU, always DISASSOCIATED.
*/
- if (pool->flags & POOL_DISASSOCIATED)
+ if (pool->flags & POOL_DISASSOCIATED) {
worker->flags |= WORKER_UNBOUND;
+ } else {
+ WARN_ON_ONCE(pool->flags & POOL_BH);
+ kthread_set_per_cpu(worker->task, pool->cpu);
+ }
+
+ if (worker->rescue_wq)
+ set_cpus_allowed_ptr(worker->task, pool_allowed_cpus(pool));
list_add_tail(&worker->node, &pool->workers);
worker->pool = pool;
struct worker_pool *pool = worker->pool;
struct completion *detach_completion = NULL;
+ /* there is one permanent BH worker per CPU which should never detach */
+ WARN_ON_ONCE(pool->flags & POOL_BH);
+
mutex_lock(&wq_pool_attach_mutex);
+ kthread_set_per_cpu(worker->task, -1);
list_del(&worker->node);
worker->pool = NULL;
- if (list_empty(&pool->workers))
+ if (list_empty(&pool->workers) && list_empty(&pool->dying_workers))
detach_completion = pool->detach_completion;
mutex_unlock(&wq_pool_attach_mutex);
*/
static struct worker *create_worker(struct worker_pool *pool)
{
- struct worker *worker = NULL;
- int id = -1;
- char id_buf[16];
+ struct worker *worker;
+ int id;
+ char id_buf[23];
/* ID is needed to determine kthread name */
- id = ida_simple_get(&pool->worker_ida, 0, 0, GFP_KERNEL);
- if (id < 0)
- goto fail;
+ id = ida_alloc(&pool->worker_ida, GFP_KERNEL);
+ if (id < 0) {
+ pr_err_once("workqueue: Failed to allocate a worker ID: %pe\n",
+ ERR_PTR(id));
+ return NULL;
+ }
worker = alloc_worker(pool->node);
- if (!worker)
+ if (!worker) {
+ pr_err_once("workqueue: Failed to allocate a worker\n");
goto fail;
+ }
worker->id = id;
- if (pool->cpu >= 0)
- snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id,
- pool->attrs->nice < 0 ? "H" : "");
- else
- snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id);
-
- worker->task = kthread_create_on_node(worker_thread, worker, pool->node,
- "kworker/%s", id_buf);
- if (IS_ERR(worker->task))
- goto fail;
+ if (!(pool->flags & POOL_BH)) {
+ if (pool->cpu >= 0)
+ snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id,
+ pool->attrs->nice < 0 ? "H" : "");
+ else
+ snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id);
+
+ worker->task = kthread_create_on_node(worker_thread, worker,
+ pool->node, "kworker/%s", id_buf);
+ if (IS_ERR(worker->task)) {
+ if (PTR_ERR(worker->task) == -EINTR) {
+ pr_err("workqueue: Interrupted when creating a worker thread \"kworker/%s\"\n",
+ id_buf);
+ } else {
+ pr_err_once("workqueue: Failed to create a worker thread: %pe",
+ worker->task);
+ }
+ goto fail;
+ }
- set_user_nice(worker->task, pool->attrs->nice);
- kthread_bind_mask(worker->task, pool->attrs->cpumask);
+ set_user_nice(worker->task, pool->attrs->nice);
+ kthread_bind_mask(worker->task, pool_allowed_cpus(pool));
+ }
/* successful, attach the worker to the pool */
worker_attach_to_pool(worker, pool);
/* start the newly created worker */
- spin_lock_irq(&pool->lock);
+ raw_spin_lock_irq(&pool->lock);
+
worker->pool->nr_workers++;
worker_enter_idle(worker);
- wake_up_process(worker->task);
- spin_unlock_irq(&pool->lock);
+
+ /*
+ * @worker is waiting on a completion in kthread() and will trigger hung
+ * check if not woken up soon. As kick_pool() is noop if @pool is empty,
+ * wake it up explicitly.
+ */
+ if (worker->task)
+ wake_up_process(worker->task);
+
+ raw_spin_unlock_irq(&pool->lock);
return worker;
fail:
- if (id >= 0)
- ida_simple_remove(&pool->worker_ida, id);
+ ida_free(&pool->worker_ida, id);
kfree(worker);
return NULL;
}
+static void unbind_worker(struct worker *worker)
+{
+ lockdep_assert_held(&wq_pool_attach_mutex);
+
+ kthread_set_per_cpu(worker->task, -1);
+ if (cpumask_intersects(wq_unbound_cpumask, cpu_active_mask))
+ WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, wq_unbound_cpumask) < 0);
+ else
+ WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0);
+}
+
+static void wake_dying_workers(struct list_head *cull_list)
+{
+ struct worker *worker, *tmp;
+
+ list_for_each_entry_safe(worker, tmp, cull_list, entry) {
+ list_del_init(&worker->entry);
+ unbind_worker(worker);
+ /*
+ * If the worker was somehow already running, then it had to be
+ * in pool->idle_list when set_worker_dying() happened or we
+ * wouldn't have gotten here.
+ *
+ * Thus, the worker must either have observed the WORKER_DIE
+ * flag, or have set its state to TASK_IDLE. Either way, the
+ * below will be observed by the worker and is safe to do
+ * outside of pool->lock.
+ */
+ wake_up_process(worker->task);
+ }
+}
+
/**
- * destroy_worker - destroy a workqueue worker
+ * set_worker_dying - Tag a worker for destruction
* @worker: worker to be destroyed
+ * @list: transfer worker away from its pool->idle_list and into list
*
- * Destroy @worker and adjust @pool stats accordingly. The worker should
- * be idle.
+ * Tag @worker for destruction and adjust @pool stats accordingly. The worker
+ * should be idle.
*
* CONTEXT:
- * spin_lock_irq(pool->lock).
+ * raw_spin_lock_irq(pool->lock).
*/
-static void destroy_worker(struct worker *worker)
+static void set_worker_dying(struct worker *worker, struct list_head *list)
{
struct worker_pool *pool = worker->pool;
lockdep_assert_held(&pool->lock);
+ lockdep_assert_held(&wq_pool_attach_mutex);
/* sanity check frenzy */
if (WARN_ON(worker->current_work) ||
pool->nr_workers--;
pool->nr_idle--;
- list_del_init(&worker->entry);
worker->flags |= WORKER_DIE;
- wake_up_process(worker->task);
+
+ list_move(&worker->entry, list);
+ list_move(&worker->node, &pool->dying_workers);
}
+/**
+ * idle_worker_timeout - check if some idle workers can now be deleted.
+ * @t: The pool's idle_timer that just expired
+ *
+ * The timer is armed in worker_enter_idle(). Note that it isn't disarmed in
+ * worker_leave_idle(), as a worker flicking between idle and active while its
+ * pool is at the too_many_workers() tipping point would cause too much timer
+ * housekeeping overhead. Since IDLE_WORKER_TIMEOUT is long enough, we just let
+ * it expire and re-evaluate things from there.
+ */
static void idle_worker_timeout(struct timer_list *t)
{
struct worker_pool *pool = from_timer(pool, t, idle_timer);
+ bool do_cull = false;
+
+ if (work_pending(&pool->idle_cull_work))
+ return;
- spin_lock_irq(&pool->lock);
+ raw_spin_lock_irq(&pool->lock);
- while (too_many_workers(pool)) {
+ if (too_many_workers(pool)) {
struct worker *worker;
unsigned long expires;
/* idle_list is kept in LIFO order, check the last one */
+ worker = list_entry(pool->idle_list.prev, struct worker, entry);
+ expires = worker->last_active + IDLE_WORKER_TIMEOUT;
+ do_cull = !time_before(jiffies, expires);
+
+ if (!do_cull)
+ mod_timer(&pool->idle_timer, expires);
+ }
+ raw_spin_unlock_irq(&pool->lock);
+
+ if (do_cull)
+ queue_work(system_unbound_wq, &pool->idle_cull_work);
+}
+
+/**
+ * idle_cull_fn - cull workers that have been idle for too long.
+ * @work: the pool's work for handling these idle workers
+ *
+ * This goes through a pool's idle workers and gets rid of those that have been
+ * idle for at least IDLE_WORKER_TIMEOUT seconds.
+ *
+ * We don't want to disturb isolated CPUs because of a pcpu kworker being
+ * culled, so this also resets worker affinity. This requires a sleepable
+ * context, hence the split between timer callback and work item.
+ */
+static void idle_cull_fn(struct work_struct *work)
+{
+ struct worker_pool *pool = container_of(work, struct worker_pool, idle_cull_work);
+ LIST_HEAD(cull_list);
+
+ /*
+ * Grabbing wq_pool_attach_mutex here ensures an already-running worker
+ * cannot proceed beyong worker_detach_from_pool() in its self-destruct
+ * path. This is required as a previously-preempted worker could run after
+ * set_worker_dying() has happened but before wake_dying_workers() did.
+ */
+ mutex_lock(&wq_pool_attach_mutex);
+ raw_spin_lock_irq(&pool->lock);
+
+ while (too_many_workers(pool)) {
+ struct worker *worker;
+ unsigned long expires;
+
worker = list_entry(pool->idle_list.prev, struct worker, entry);
expires = worker->last_active + IDLE_WORKER_TIMEOUT;
break;
}
- destroy_worker(worker);
+ set_worker_dying(worker, &cull_list);
}
- spin_unlock_irq(&pool->lock);
+ raw_spin_unlock_irq(&pool->lock);
+ wake_dying_workers(&cull_list);
+ mutex_unlock(&wq_pool_attach_mutex);
}
static void send_mayday(struct work_struct *work)
get_pwq(pwq);
list_add_tail(&pwq->mayday_node, &wq->maydays);
wake_up_process(wq->rescuer->task);
+ pwq->stats[PWQ_STAT_MAYDAY]++;
}
}
struct worker_pool *pool = from_timer(pool, t, mayday_timer);
struct work_struct *work;
- spin_lock_irq(&pool->lock);
- spin_lock(&wq_mayday_lock); /* for wq->maydays */
+ raw_spin_lock_irq(&pool->lock);
+ raw_spin_lock(&wq_mayday_lock); /* for wq->maydays */
if (need_to_create_worker(pool)) {
/*
send_mayday(work);
}
- spin_unlock(&wq_mayday_lock);
- spin_unlock_irq(&pool->lock);
+ raw_spin_unlock(&wq_mayday_lock);
+ raw_spin_unlock_irq(&pool->lock);
mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL);
}
* may_start_working() %true.
*
* LOCKING:
- * spin_lock_irq(pool->lock) which may be released and regrabbed
+ * raw_spin_lock_irq(pool->lock) which may be released and regrabbed
* multiple times. Does GFP_KERNEL allocations. Called only from
* manager.
*/
__acquires(&pool->lock)
{
restart:
- spin_unlock_irq(&pool->lock);
+ raw_spin_unlock_irq(&pool->lock);
/* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
}
del_timer_sync(&pool->mayday_timer);
- spin_lock_irq(&pool->lock);
+ raw_spin_lock_irq(&pool->lock);
/*
* This is necessary even after a new worker was just successfully
* created as @pool->lock was dropped and the new worker might have
* and may_start_working() is true.
*
* CONTEXT:
- * spin_lock_irq(pool->lock) which may be released and regrabbed
+ * raw_spin_lock_irq(pool->lock) which may be released and regrabbed
* multiple times. Does GFP_KERNEL allocations.
*
* Return:
pool->manager = NULL;
pool->flags &= ~POOL_MANAGER_ACTIVE;
- wake_up(&wq_manager_wait);
+ rcuwait_wake_up(&manager_wait);
return true;
}
* call this function to process a work.
*
* CONTEXT:
- * spin_lock_irq(pool->lock) which is released and regrabbed.
+ * raw_spin_lock_irq(pool->lock) which is released and regrabbed.
*/
static void process_one_work(struct worker *worker, struct work_struct *work)
__releases(&pool->lock)
{
struct pool_workqueue *pwq = get_work_pwq(work);
struct worker_pool *pool = worker->pool;
- bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE;
- int work_color;
- struct worker *collision;
+ unsigned long work_data;
+ int lockdep_start_depth, rcu_start_depth;
+ bool bh_draining = pool->flags & POOL_BH_DRAINING;
#ifdef CONFIG_LOCKDEP
/*
* It is permissible to free the struct work_struct from
WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
raw_smp_processor_id() != pool->cpu);
- /*
- * A single work shouldn't be executed concurrently by
- * multiple workers on a single cpu. Check whether anyone is
- * already processing the work. If so, defer the work to the
- * currently executing one.
- */
- collision = find_worker_executing_work(pool, work);
- if (unlikely(collision)) {
- move_linked_works(work, &collision->scheduled, NULL);
- return;
- }
-
/* claim and dequeue */
debug_work_deactivate(work);
hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work);
worker->current_work = work;
worker->current_func = work->func;
worker->current_pwq = pwq;
- work_color = get_work_color(work);
+ if (worker->task)
+ worker->current_at = worker->task->se.sum_exec_runtime;
+ work_data = *work_data_bits(work);
+ worker->current_color = get_work_color(work_data);
/*
* Record wq name for cmdline and debug reporting, may get
* of concurrency management and the next code block will chain
* execution of the pending work items.
*/
- if (unlikely(cpu_intensive))
+ if (unlikely(pwq->wq->flags & WQ_CPU_INTENSIVE))
worker_set_flags(worker, WORKER_CPU_INTENSIVE);
/*
- * Wake up another worker if necessary. The condition is always
- * false for normal per-cpu workers since nr_running would always
- * be >= 1 at this point. This is used to chain execution of the
- * pending work items for WORKER_NOT_RUNNING workers such as the
- * UNBOUND and CPU_INTENSIVE ones.
+ * Kick @pool if necessary. It's always noop for per-cpu worker pools
+ * since nr_running would always be >= 1 at this point. This is used to
+ * chain execution of the pending work items for WORKER_NOT_RUNNING
+ * workers such as the UNBOUND and CPU_INTENSIVE ones.
*/
- if (need_more_worker(pool))
- wake_up_worker(pool);
+ kick_pool(pool);
/*
* Record the last pool and clear PENDING which should be the last
* PENDING and queued state changes happen together while IRQ is
* disabled.
*/
- set_work_pool_and_clear_pending(work, pool->id);
+ set_work_pool_and_clear_pending(work, pool->id, 0);
- spin_unlock_irq(&pool->lock);
+ pwq->stats[PWQ_STAT_STARTED]++;
+ raw_spin_unlock_irq(&pool->lock);
- lock_map_acquire(&pwq->wq->lockdep_map);
+ rcu_start_depth = rcu_preempt_depth();
+ lockdep_start_depth = lockdep_depth(current);
+ /* see drain_dead_softirq_workfn() */
+ if (!bh_draining)
+ lock_map_acquire(&pwq->wq->lockdep_map);
lock_map_acquire(&lockdep_map);
/*
* Strictly speaking we should mark the invariant state without holding
* While we must be careful to not use "work" after this, the trace
* point will only record its address.
*/
- trace_workqueue_execute_end(work);
+ trace_workqueue_execute_end(work, worker->current_func);
+ pwq->stats[PWQ_STAT_COMPLETED]++;
lock_map_release(&lockdep_map);
- lock_map_release(&pwq->wq->lockdep_map);
+ if (!bh_draining)
+ lock_map_release(&pwq->wq->lockdep_map);
- if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
- pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
- " last function: %ps\n",
- current->comm, preempt_count(), task_pid_nr(current),
+ if (unlikely((worker->task && in_atomic()) ||
+ lockdep_depth(current) != lockdep_start_depth ||
+ rcu_preempt_depth() != rcu_start_depth)) {
+ pr_err("BUG: workqueue leaked atomic, lock or RCU: %s[%d]\n"
+ " preempt=0x%08x lock=%d->%d RCU=%d->%d workfn=%ps\n",
+ current->comm, task_pid_nr(current), preempt_count(),
+ lockdep_start_depth, lockdep_depth(current),
+ rcu_start_depth, rcu_preempt_depth(),
worker->current_func);
debug_show_held_locks(current);
dump_stack();
}
/*
- * The following prevents a kworker from hogging CPU on !PREEMPT
+ * The following prevents a kworker from hogging CPU on !PREEMPTION
* kernels, where a requeueing work item waiting for something to
* happen could deadlock with stop_machine as such work item could
* indefinitely requeue itself while all other CPUs are trapped in
* stop_machine. At the same time, report a quiescent RCU state so
* the same condition doesn't freeze RCU.
*/
- cond_resched();
+ if (worker->task)
+ cond_resched();
- spin_lock_irq(&pool->lock);
+ raw_spin_lock_irq(&pool->lock);
- /* clear cpu intensive status */
- if (unlikely(cpu_intensive))
- worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
+ /*
+ * In addition to %WQ_CPU_INTENSIVE, @worker may also have been marked
+ * CPU intensive by wq_worker_tick() if @work hogged CPU longer than
+ * wq_cpu_intensive_thresh_us. Clear it.
+ */
+ worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
/* tag the worker for identification in schedule() */
worker->last_func = worker->current_func;
worker->current_work = NULL;
worker->current_func = NULL;
worker->current_pwq = NULL;
- pwq_dec_nr_in_flight(pwq, work_color);
+ worker->current_color = INT_MAX;
+
+ /* must be the last step, see the function comment */
+ pwq_dec_nr_in_flight(pwq, work_data);
}
/**
* fetches a work from the top and executes it.
*
* CONTEXT:
- * spin_lock_irq(pool->lock) which may be released and regrabbed
+ * raw_spin_lock_irq(pool->lock) which may be released and regrabbed
* multiple times.
*/
static void process_scheduled_works(struct worker *worker)
{
- while (!list_empty(&worker->scheduled)) {
- struct work_struct *work = list_first_entry(&worker->scheduled,
- struct work_struct, entry);
+ struct work_struct *work;
+ bool first = true;
+
+ while ((work = list_first_entry_or_null(&worker->scheduled,
+ struct work_struct, entry))) {
+ if (first) {
+ worker->pool->watchdog_ts = jiffies;
+ first = false;
+ }
process_one_work(worker, work);
}
}
/* tell the scheduler that this is a workqueue worker */
set_pf_worker(true);
woke_up:
- spin_lock_irq(&pool->lock);
+ raw_spin_lock_irq(&pool->lock);
/* am I supposed to die? */
if (unlikely(worker->flags & WORKER_DIE)) {
- spin_unlock_irq(&pool->lock);
- WARN_ON_ONCE(!list_empty(&worker->entry));
+ raw_spin_unlock_irq(&pool->lock);
set_pf_worker(false);
set_task_comm(worker->task, "kworker/dying");
- ida_simple_remove(&pool->worker_ida, worker->id);
+ ida_free(&pool->worker_ida, worker->id);
worker_detach_from_pool(worker);
+ WARN_ON_ONCE(!list_empty(&worker->entry));
kfree(worker);
return 0;
}
list_first_entry(&pool->worklist,
struct work_struct, entry);
- pool->watchdog_ts = jiffies;
-
- if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
- /* optimization path, not strictly necessary */
- process_one_work(worker, work);
- if (unlikely(!list_empty(&worker->scheduled)))
- process_scheduled_works(worker);
- } else {
- move_linked_works(work, &worker->scheduled, NULL);
+ if (assign_work(work, worker, NULL))
process_scheduled_works(worker);
- }
} while (keep_working(pool));
worker_set_flags(worker, WORKER_PREP);
*/
worker_enter_idle(worker);
__set_current_state(TASK_IDLE);
- spin_unlock_irq(&pool->lock);
+ raw_spin_unlock_irq(&pool->lock);
schedule();
goto woke_up;
}
{
struct worker *rescuer = __rescuer;
struct workqueue_struct *wq = rescuer->rescue_wq;
- struct list_head *scheduled = &rescuer->scheduled;
bool should_stop;
set_user_nice(current, RESCUER_NICE_LEVEL);
should_stop = kthread_should_stop();
/* see whether any pwq is asking for help */
- spin_lock_irq(&wq_mayday_lock);
+ raw_spin_lock_irq(&wq_mayday_lock);
while (!list_empty(&wq->maydays)) {
struct pool_workqueue *pwq = list_first_entry(&wq->maydays,
struct pool_workqueue, mayday_node);
struct worker_pool *pool = pwq->pool;
struct work_struct *work, *n;
- bool first = true;
__set_current_state(TASK_RUNNING);
list_del_init(&pwq->mayday_node);
- spin_unlock_irq(&wq_mayday_lock);
+ raw_spin_unlock_irq(&wq_mayday_lock);
worker_attach_to_pool(rescuer, pool);
- spin_lock_irq(&pool->lock);
+ raw_spin_lock_irq(&pool->lock);
/*
* Slurp in all works issued via this workqueue and
* process'em.
*/
- WARN_ON_ONCE(!list_empty(scheduled));
+ WARN_ON_ONCE(!list_empty(&rescuer->scheduled));
list_for_each_entry_safe(work, n, &pool->worklist, entry) {
- if (get_work_pwq(work) == pwq) {
- if (first)
- pool->watchdog_ts = jiffies;
- move_linked_works(work, scheduled, &n);
- }
- first = false;
+ if (get_work_pwq(work) == pwq &&
+ assign_work(work, rescuer, &n))
+ pwq->stats[PWQ_STAT_RESCUED]++;
}
- if (!list_empty(scheduled)) {
+ if (!list_empty(&rescuer->scheduled)) {
process_scheduled_works(rescuer);
/*
* The above execution of rescued work items could
* have created more to rescue through
- * pwq_activate_first_delayed() or chained
+ * pwq_activate_first_inactive() or chained
* queueing. Let's put @pwq back on mayday list so
* that such back-to-back work items, which may be
* being used to relieve memory pressure, don't
* incur MAYDAY_INTERVAL delay inbetween.
*/
- if (need_to_create_worker(pool)) {
- spin_lock(&wq_mayday_lock);
- get_pwq(pwq);
- list_move_tail(&pwq->mayday_node, &wq->maydays);
- spin_unlock(&wq_mayday_lock);
+ if (pwq->nr_active && need_to_create_worker(pool)) {
+ raw_spin_lock(&wq_mayday_lock);
+ /*
+ * Queue iff we aren't racing destruction
+ * and somebody else hasn't queued it already.
+ */
+ if (wq->rescuer && list_empty(&pwq->mayday_node)) {
+ get_pwq(pwq);
+ list_add_tail(&pwq->mayday_node, &wq->maydays);
+ }
+ raw_spin_unlock(&wq_mayday_lock);
}
}
put_pwq(pwq);
/*
- * Leave this pool. If need_more_worker() is %true, notify a
- * regular worker; otherwise, we end up with 0 concurrency
- * and stalling the execution.
+ * Leave this pool. Notify regular workers; otherwise, we end up
+ * with 0 concurrency and stalling the execution.
*/
- if (need_more_worker(pool))
- wake_up_worker(pool);
+ kick_pool(pool);
- spin_unlock_irq(&pool->lock);
+ raw_spin_unlock_irq(&pool->lock);
worker_detach_from_pool(rescuer);
- spin_lock_irq(&wq_mayday_lock);
+ raw_spin_lock_irq(&wq_mayday_lock);
}
- spin_unlock_irq(&wq_mayday_lock);
+ raw_spin_unlock_irq(&wq_mayday_lock);
if (should_stop) {
__set_current_state(TASK_RUNNING);
goto repeat;
}
+static void bh_worker(struct worker *worker)
+{
+ struct worker_pool *pool = worker->pool;
+ int nr_restarts = BH_WORKER_RESTARTS;
+ unsigned long end = jiffies + BH_WORKER_JIFFIES;
+
+ raw_spin_lock_irq(&pool->lock);
+ worker_leave_idle(worker);
+
+ /*
+ * This function follows the structure of worker_thread(). See there for
+ * explanations on each step.
+ */
+ if (!need_more_worker(pool))
+ goto done;
+
+ WARN_ON_ONCE(!list_empty(&worker->scheduled));
+ worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND);
+
+ do {
+ struct work_struct *work =
+ list_first_entry(&pool->worklist,
+ struct work_struct, entry);
+
+ if (assign_work(work, worker, NULL))
+ process_scheduled_works(worker);
+ } while (keep_working(pool) &&
+ --nr_restarts && time_before(jiffies, end));
+
+ worker_set_flags(worker, WORKER_PREP);
+done:
+ worker_enter_idle(worker);
+ kick_pool(pool);
+ raw_spin_unlock_irq(&pool->lock);
+}
+
+/*
+ * TODO: Convert all tasklet users to workqueue and use softirq directly.
+ *
+ * This is currently called from tasklet[_hi]action() and thus is also called
+ * whenever there are tasklets to run. Let's do an early exit if there's nothing
+ * queued. Once conversion from tasklet is complete, the need_more_worker() test
+ * can be dropped.
+ *
+ * After full conversion, we'll add worker->softirq_action, directly use the
+ * softirq action and obtain the worker pointer from the softirq_action pointer.
+ */
+void workqueue_softirq_action(bool highpri)
+{
+ struct worker_pool *pool =
+ &per_cpu(bh_worker_pools, smp_processor_id())[highpri];
+ if (need_more_worker(pool))
+ bh_worker(list_first_entry(&pool->workers, struct worker, node));
+}
+
+struct wq_drain_dead_softirq_work {
+ struct work_struct work;
+ struct worker_pool *pool;
+ struct completion done;
+};
+
+static void drain_dead_softirq_workfn(struct work_struct *work)
+{
+ struct wq_drain_dead_softirq_work *dead_work =
+ container_of(work, struct wq_drain_dead_softirq_work, work);
+ struct worker_pool *pool = dead_work->pool;
+ bool repeat;
+
+ /*
+ * @pool's CPU is dead and we want to execute its still pending work
+ * items from this BH work item which is running on a different CPU. As
+ * its CPU is dead, @pool can't be kicked and, as work execution path
+ * will be nested, a lockdep annotation needs to be suppressed. Mark
+ * @pool with %POOL_BH_DRAINING for the special treatments.
+ */
+ raw_spin_lock_irq(&pool->lock);
+ pool->flags |= POOL_BH_DRAINING;
+ raw_spin_unlock_irq(&pool->lock);
+
+ bh_worker(list_first_entry(&pool->workers, struct worker, node));
+
+ raw_spin_lock_irq(&pool->lock);
+ pool->flags &= ~POOL_BH_DRAINING;
+ repeat = need_more_worker(pool);
+ raw_spin_unlock_irq(&pool->lock);
+
+ /*
+ * bh_worker() might hit consecutive execution limit and bail. If there
+ * still are pending work items, reschedule self and return so that we
+ * don't hog this CPU's BH.
+ */
+ if (repeat) {
+ if (pool->attrs->nice == HIGHPRI_NICE_LEVEL)
+ queue_work(system_bh_highpri_wq, work);
+ else
+ queue_work(system_bh_wq, work);
+ } else {
+ complete(&dead_work->done);
+ }
+}
+
+/*
+ * @cpu is dead. Drain the remaining BH work items on the current CPU. It's
+ * possible to allocate dead_work per CPU and avoid flushing. However, then we
+ * have to worry about draining overlapping with CPU coming back online or
+ * nesting (one CPU's dead_work queued on another CPU which is also dead and so
+ * on). Let's keep it simple and drain them synchronously. These are BH work
+ * items which shouldn't be requeued on the same pool. Shouldn't take long.
+ */
+void workqueue_softirq_dead(unsigned int cpu)
+{
+ int i;
+
+ for (i = 0; i < NR_STD_WORKER_POOLS; i++) {
+ struct worker_pool *pool = &per_cpu(bh_worker_pools, cpu)[i];
+ struct wq_drain_dead_softirq_work dead_work;
+
+ if (!need_more_worker(pool))
+ continue;
+
+ INIT_WORK(&dead_work.work, drain_dead_softirq_workfn);
+ dead_work.pool = pool;
+ init_completion(&dead_work.done);
+
+ if (pool->attrs->nice == HIGHPRI_NICE_LEVEL)
+ queue_work(system_bh_highpri_wq, &dead_work.work);
+ else
+ queue_work(system_bh_wq, &dead_work.work);
+
+ wait_for_completion(&dead_work.done);
+ }
+}
+
/**
* check_flush_dependency - check for flush dependency sanity
* @target_wq: workqueue being flushed
* underneath us, so we can't reliably determine pwq from @target.
*
* CONTEXT:
- * spin_lock_irq(pool->lock).
+ * raw_spin_lock_irq(pool->lock).
*/
static void insert_wq_barrier(struct pool_workqueue *pwq,
struct wq_barrier *barr,
struct work_struct *target, struct worker *worker)
{
+ static __maybe_unused struct lock_class_key bh_key, thr_key;
+ unsigned int work_flags = 0;
+ unsigned int work_color;
struct list_head *head;
- unsigned int linked = 0;
/*
* debugobject calls are safe here even with pool->lock locked
* as we know for sure that this will not trigger any of the
* checks and call back into the fixup functions where we
* might deadlock.
+ *
+ * BH and threaded workqueues need separate lockdep keys to avoid
+ * spuriously triggering "inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W}
+ * usage".
*/
- INIT_WORK_ONSTACK(&barr->work, wq_barrier_func);
+ INIT_WORK_ONSTACK_KEY(&barr->work, wq_barrier_func,
+ (pwq->wq->flags & WQ_BH) ? &bh_key : &thr_key);
__set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
init_completion_map(&barr->done, &target->lockdep_map);
barr->task = current;
+ /* The barrier work item does not participate in nr_active. */
+ work_flags |= WORK_STRUCT_INACTIVE;
+
/*
* If @target is currently being executed, schedule the
* barrier to the worker; otherwise, put it after @target.
*/
- if (worker)
+ if (worker) {
head = worker->scheduled.next;
- else {
+ work_color = worker->current_color;
+ } else {
unsigned long *bits = work_data_bits(target);
head = target->entry.next;
/* there can already be other linked works, inherit and set */
- linked = *bits & WORK_STRUCT_LINKED;
+ work_flags |= *bits & WORK_STRUCT_LINKED;
+ work_color = get_work_color(*bits);
__set_bit(WORK_STRUCT_LINKED_BIT, bits);
}
- debug_work_activate(&barr->work);
- insert_work(pwq, &barr->work, head,
- work_color_to_flags(WORK_NO_COLOR) | linked);
+ pwq->nr_in_flight[work_color]++;
+ work_flags |= work_color_to_flags(work_color);
+
+ insert_work(pwq, &barr->work, head, work_flags);
}
/**
for_each_pwq(pwq, wq) {
struct worker_pool *pool = pwq->pool;
- spin_lock_irq(&pool->lock);
+ raw_spin_lock_irq(&pool->lock);
if (flush_color >= 0) {
WARN_ON_ONCE(pwq->flush_color != -1);
pwq->work_color = work_color;
}
- spin_unlock_irq(&pool->lock);
+ raw_spin_unlock_irq(&pool->lock);
}
if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush))
return wait;
}
+static void touch_wq_lockdep_map(struct workqueue_struct *wq)
+{
+#ifdef CONFIG_LOCKDEP
+ if (wq->flags & WQ_BH)
+ local_bh_disable();
+
+ lock_map_acquire(&wq->lockdep_map);
+ lock_map_release(&wq->lockdep_map);
+
+ if (wq->flags & WQ_BH)
+ local_bh_enable();
+#endif
+}
+
+static void touch_work_lockdep_map(struct work_struct *work,
+ struct workqueue_struct *wq)
+{
+#ifdef CONFIG_LOCKDEP
+ if (wq->flags & WQ_BH)
+ local_bh_disable();
+
+ lock_map_acquire(&work->lockdep_map);
+ lock_map_release(&work->lockdep_map);
+
+ if (wq->flags & WQ_BH)
+ local_bh_enable();
+#endif
+}
+
/**
- * flush_workqueue - ensure that any scheduled work has run to completion.
+ * __flush_workqueue - ensure that any scheduled work has run to completion.
* @wq: workqueue to flush
*
* This function sleeps until all work items which were queued on entry
* have finished execution, but it is not livelocked by new incoming ones.
*/
-void flush_workqueue(struct workqueue_struct *wq)
+void __flush_workqueue(struct workqueue_struct *wq)
{
struct wq_flusher this_flusher = {
.list = LIST_HEAD_INIT(this_flusher.list),
if (WARN_ON(!wq_online))
return;
- lock_map_acquire(&wq->lockdep_map);
- lock_map_release(&wq->lockdep_map);
+ touch_wq_lockdep_map(wq);
mutex_lock(&wq->mutex);
* First flushers are responsible for cascading flushes and
* handling overflow. Non-first flushers can simply return.
*/
- if (wq->first_flusher != &this_flusher)
+ if (READ_ONCE(wq->first_flusher) != &this_flusher)
return;
mutex_lock(&wq->mutex);
if (wq->first_flusher != &this_flusher)
goto out_unlock;
- wq->first_flusher = NULL;
+ WRITE_ONCE(wq->first_flusher, NULL);
WARN_ON_ONCE(!list_empty(&this_flusher.list));
WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
out_unlock:
mutex_unlock(&wq->mutex);
}
-EXPORT_SYMBOL(flush_workqueue);
+EXPORT_SYMBOL(__flush_workqueue);
/**
* drain_workqueue - drain a workqueue
wq->flags |= __WQ_DRAINING;
mutex_unlock(&wq->mutex);
reflush:
- flush_workqueue(wq);
+ __flush_workqueue(wq);
mutex_lock(&wq->mutex);
for_each_pwq(pwq, wq) {
bool drained;
- spin_lock_irq(&pwq->pool->lock);
- drained = !pwq->nr_active && list_empty(&pwq->delayed_works);
- spin_unlock_irq(&pwq->pool->lock);
+ raw_spin_lock_irq(&pwq->pool->lock);
+ drained = pwq_is_empty(pwq);
+ raw_spin_unlock_irq(&pwq->pool->lock);
if (drained)
continue;
if (++flush_cnt == 10 ||
(flush_cnt % 100 == 0 && flush_cnt <= 1000))
- pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n",
- wq->name, flush_cnt);
+ pr_warn("workqueue %s: %s() isn't complete after %u tries\n",
+ wq->name, __func__, flush_cnt);
mutex_unlock(&wq->mutex);
goto reflush;
struct worker *worker = NULL;
struct worker_pool *pool;
struct pool_workqueue *pwq;
+ struct workqueue_struct *wq;
might_sleep();
return false;
}
- spin_lock_irq(&pool->lock);
+ raw_spin_lock_irq(&pool->lock);
/* see the comment in try_to_grab_pending() with the same code */
pwq = get_work_pwq(work);
if (pwq) {
pwq = worker->current_pwq;
}
- check_flush_dependency(pwq->wq, work);
+ wq = pwq->wq;
+ check_flush_dependency(wq, work);
insert_wq_barrier(pwq, barr, work, worker);
- spin_unlock_irq(&pool->lock);
+ raw_spin_unlock_irq(&pool->lock);
+
+ touch_work_lockdep_map(work, wq);
/*
* Force a lock recursion deadlock when using flush_work() inside a
* workqueues the deadlock happens when the rescuer stalls, blocking
* forward progress.
*/
- if (!from_cancel &&
- (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer)) {
- lock_map_acquire(&pwq->wq->lockdep_map);
- lock_map_release(&pwq->wq->lockdep_map);
- }
+ if (!from_cancel && (wq->saved_max_active == 1 || wq->rescuer))
+ touch_wq_lockdep_map(wq);
+
rcu_read_unlock();
return true;
already_gone:
- spin_unlock_irq(&pool->lock);
+ raw_spin_unlock_irq(&pool->lock);
rcu_read_unlock();
return false;
}
if (WARN_ON(!work->func))
return false;
- if (!from_cancel) {
- lock_map_acquire(&work->lockdep_map);
- lock_map_release(&work->lockdep_map);
- }
-
if (start_flush_work(work, &barr, from_cancel)) {
wait_for_completion(&barr.done);
destroy_work_on_stack(&barr.work);
}
EXPORT_SYMBOL_GPL(flush_work);
-struct cwt_wait {
- wait_queue_entry_t wait;
- struct work_struct *work;
-};
-
-static int cwt_wakefn(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
-{
- struct cwt_wait *cwait = container_of(wait, struct cwt_wait, wait);
-
- if (cwait->work != key)
- return 0;
- return autoremove_wake_function(wait, mode, sync, key);
-}
-
-static bool __cancel_work_timer(struct work_struct *work, bool is_dwork)
-{
- static DECLARE_WAIT_QUEUE_HEAD(cancel_waitq);
- unsigned long flags;
- int ret;
-
- do {
- ret = try_to_grab_pending(work, is_dwork, &flags);
- /*
- * If someone else is already canceling, wait for it to
- * finish. flush_work() doesn't work for PREEMPT_NONE
- * because we may get scheduled between @work's completion
- * and the other canceling task resuming and clearing
- * CANCELING - flush_work() will return false immediately
- * as @work is no longer busy, try_to_grab_pending() will
- * return -ENOENT as @work is still being canceled and the
- * other canceling task won't be able to clear CANCELING as
- * we're hogging the CPU.
- *
- * Let's wait for completion using a waitqueue. As this
- * may lead to the thundering herd problem, use a custom
- * wake function which matches @work along with exclusive
- * wait and wakeup.
- */
- if (unlikely(ret == -ENOENT)) {
- struct cwt_wait cwait;
-
- init_wait(&cwait.wait);
- cwait.wait.func = cwt_wakefn;
- cwait.work = work;
-
- prepare_to_wait_exclusive(&cancel_waitq, &cwait.wait,
- TASK_UNINTERRUPTIBLE);
- if (work_is_canceling(work))
- schedule();
- finish_wait(&cancel_waitq, &cwait.wait);
- }
- } while (unlikely(ret < 0));
-
- /* tell other tasks trying to grab @work to back off */
- mark_work_canceling(work);
- local_irq_restore(flags);
-
- /*
- * This allows canceling during early boot. We know that @work
- * isn't executing.
- */
- if (wq_online)
- __flush_work(work, true);
-
- clear_work_data(work);
-
- /*
- * Paired with prepare_to_wait() above so that either
- * waitqueue_active() is visible here or !work_is_canceling() is
- * visible there.
- */
- smp_mb();
- if (waitqueue_active(&cancel_waitq))
- __wake_up(&cancel_waitq, TASK_NORMAL, 1, work);
-
- return ret;
-}
-
-/**
- * cancel_work_sync - cancel a work and wait for it to finish
- * @work: the work to cancel
- *
- * Cancel @work and wait for its execution to finish. This function
- * can be used even if the work re-queues itself or migrates to
- * another workqueue. On return from this function, @work is
- * guaranteed to be not pending or executing on any CPU.
- *
- * cancel_work_sync(&delayed_work->work) must not be used for
- * delayed_work's. Use cancel_delayed_work_sync() instead.
- *
- * The caller must ensure that the workqueue on which @work was last
- * queued can't be destroyed before this function returns.
- *
- * Return:
- * %true if @work was pending, %false otherwise.
- */
-bool cancel_work_sync(struct work_struct *work)
-{
- return __cancel_work_timer(work, false);
-}
-EXPORT_SYMBOL_GPL(cancel_work_sync);
-
/**
* flush_delayed_work - wait for a dwork to finish executing the last queueing
* @dwork: the delayed work to flush
}
EXPORT_SYMBOL(flush_rcu_work);
-static bool __cancel_work(struct work_struct *work, bool is_dwork)
+static bool __cancel_work(struct work_struct *work, u32 cflags)
{
- unsigned long flags;
+ unsigned long irq_flags;
int ret;
do {
- ret = try_to_grab_pending(work, is_dwork, &flags);
+ ret = try_to_grab_pending(work, cflags, &irq_flags);
} while (unlikely(ret == -EAGAIN));
if (unlikely(ret < 0))
return false;
- set_work_pool_and_clear_pending(work, get_work_pool_id(work));
- local_irq_restore(flags);
+ set_work_pool_and_clear_pending(work, get_work_pool_id(work), 0);
+ local_irq_restore(irq_flags);
+ return ret;
+}
+
+static bool __cancel_work_sync(struct work_struct *work, u32 cflags)
+{
+ unsigned long irq_flags;
+ bool ret;
+
+ /* claim @work and tell other tasks trying to grab @work to back off */
+ ret = work_grab_pending(work, cflags, &irq_flags);
+ mark_work_canceling(work);
+ local_irq_restore(irq_flags);
+
+ /*
+ * Skip __flush_work() during early boot when we know that @work isn't
+ * executing. This allows canceling during early boot.
+ */
+ if (wq_online)
+ __flush_work(work, true);
+
+ /*
+ * smp_mb() at the end of set_work_pool_and_clear_pending() is paired
+ * with prepare_to_wait() above so that either waitqueue_active() is
+ * visible here or !work_is_canceling() is visible there.
+ */
+ set_work_pool_and_clear_pending(work, WORK_OFFQ_POOL_NONE, 0);
+
+ if (waitqueue_active(&wq_cancel_waitq))
+ __wake_up(&wq_cancel_waitq, TASK_NORMAL, 1, work);
+
return ret;
}
+/*
+ * See cancel_delayed_work()
+ */
+bool cancel_work(struct work_struct *work)
+{
+ return __cancel_work(work, 0);
+}
+EXPORT_SYMBOL(cancel_work);
+
+/**
+ * cancel_work_sync - cancel a work and wait for it to finish
+ * @work: the work to cancel
+ *
+ * Cancel @work and wait for its execution to finish. This function
+ * can be used even if the work re-queues itself or migrates to
+ * another workqueue. On return from this function, @work is
+ * guaranteed to be not pending or executing on any CPU.
+ *
+ * cancel_work_sync(&delayed_work->work) must not be used for
+ * delayed_work's. Use cancel_delayed_work_sync() instead.
+ *
+ * The caller must ensure that the workqueue on which @work was last
+ * queued can't be destroyed before this function returns.
+ *
+ * Return:
+ * %true if @work was pending, %false otherwise.
+ */
+bool cancel_work_sync(struct work_struct *work)
+{
+ return __cancel_work_sync(work, 0);
+}
+EXPORT_SYMBOL_GPL(cancel_work_sync);
+
/**
* cancel_delayed_work - cancel a delayed work
* @dwork: delayed_work to cancel
*/
bool cancel_delayed_work(struct delayed_work *dwork)
{
- return __cancel_work(&dwork->work, true);
+ return __cancel_work(&dwork->work, WORK_CANCEL_DELAYED);
}
EXPORT_SYMBOL(cancel_delayed_work);
*/
bool cancel_delayed_work_sync(struct delayed_work *dwork)
{
- return __cancel_work_timer(&dwork->work, true);
+ return __cancel_work_sync(&dwork->work, WORK_CANCEL_DELAYED);
}
EXPORT_SYMBOL(cancel_delayed_work_sync);
if (!works)
return -ENOMEM;
- get_online_cpus();
+ cpus_read_lock();
for_each_online_cpu(cpu) {
struct work_struct *work = per_cpu_ptr(works, cpu);
for_each_online_cpu(cpu)
flush_work(per_cpu_ptr(works, cpu));
- put_online_cpus();
+ cpus_read_unlock();
free_percpu(works);
return 0;
}
{
if (attrs) {
free_cpumask_var(attrs->cpumask);
+ free_cpumask_var(attrs->__pod_cpumask);
kfree(attrs);
}
}
/**
* alloc_workqueue_attrs - allocate a workqueue_attrs
- * @gfp_mask: allocation mask to use
*
* Allocate a new workqueue_attrs, initialize with default settings and
* return it.
*
* Return: The allocated new workqueue_attr on success. %NULL on failure.
*/
-struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask)
+struct workqueue_attrs *alloc_workqueue_attrs(void)
{
struct workqueue_attrs *attrs;
- attrs = kzalloc(sizeof(*attrs), gfp_mask);
+ attrs = kzalloc(sizeof(*attrs), GFP_KERNEL);
if (!attrs)
goto fail;
- if (!alloc_cpumask_var(&attrs->cpumask, gfp_mask))
+ if (!alloc_cpumask_var(&attrs->cpumask, GFP_KERNEL))
+ goto fail;
+ if (!alloc_cpumask_var(&attrs->__pod_cpumask, GFP_KERNEL))
goto fail;
cpumask_copy(attrs->cpumask, cpu_possible_mask);
+ attrs->affn_scope = WQ_AFFN_DFL;
return attrs;
fail:
free_workqueue_attrs(attrs);
{
to->nice = from->nice;
cpumask_copy(to->cpumask, from->cpumask);
+ cpumask_copy(to->__pod_cpumask, from->__pod_cpumask);
+ to->affn_strict = from->affn_strict;
+
/*
- * Unlike hash and equality test, this function doesn't ignore
- * ->no_numa as it is used for both pool and wq attrs. Instead,
- * get_unbound_pool() explicitly clears ->no_numa after copying.
+ * Unlike hash and equality test, copying shouldn't ignore wq-only
+ * fields as copying is used for both pool and wq attrs. Instead,
+ * get_unbound_pool() explicitly clears the fields.
*/
- to->no_numa = from->no_numa;
+ to->affn_scope = from->affn_scope;
+ to->ordered = from->ordered;
+}
+
+/*
+ * Some attrs fields are workqueue-only. Clear them for worker_pool's. See the
+ * comments in 'struct workqueue_attrs' definition.
+ */
+static void wqattrs_clear_for_pool(struct workqueue_attrs *attrs)
+{
+ attrs->affn_scope = WQ_AFFN_NR_TYPES;
+ attrs->ordered = false;
}
/* hash value of the content of @attr */
hash = jhash_1word(attrs->nice, hash);
hash = jhash(cpumask_bits(attrs->cpumask),
BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash);
+ hash = jhash(cpumask_bits(attrs->__pod_cpumask),
+ BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash);
+ hash = jhash_1word(attrs->affn_strict, hash);
return hash;
}
return false;
if (!cpumask_equal(a->cpumask, b->cpumask))
return false;
+ if (!cpumask_equal(a->__pod_cpumask, b->__pod_cpumask))
+ return false;
+ if (a->affn_strict != b->affn_strict)
+ return false;
return true;
}
+/* Update @attrs with actually available CPUs */
+static void wqattrs_actualize_cpumask(struct workqueue_attrs *attrs,
+ const cpumask_t *unbound_cpumask)
+{
+ /*
+ * Calculate the effective CPU mask of @attrs given @unbound_cpumask. If
+ * @attrs->cpumask doesn't overlap with @unbound_cpumask, we fallback to
+ * @unbound_cpumask.
+ */
+ cpumask_and(attrs->cpumask, attrs->cpumask, unbound_cpumask);
+ if (unlikely(cpumask_empty(attrs->cpumask)))
+ cpumask_copy(attrs->cpumask, unbound_cpumask);
+}
+
+/* find wq_pod_type to use for @attrs */
+static const struct wq_pod_type *
+wqattrs_pod_type(const struct workqueue_attrs *attrs)
+{
+ enum wq_affn_scope scope;
+ struct wq_pod_type *pt;
+
+ /* to synchronize access to wq_affn_dfl */
+ lockdep_assert_held(&wq_pool_mutex);
+
+ if (attrs->affn_scope == WQ_AFFN_DFL)
+ scope = wq_affn_dfl;
+ else
+ scope = attrs->affn_scope;
+
+ pt = &wq_pod_types[scope];
+
+ if (!WARN_ON_ONCE(attrs->affn_scope == WQ_AFFN_NR_TYPES) &&
+ likely(pt->nr_pods))
+ return pt;
+
+ /*
+ * Before workqueue_init_topology(), only SYSTEM is available which is
+ * initialized in workqueue_init_early().
+ */
+ pt = &wq_pod_types[WQ_AFFN_SYSTEM];
+ BUG_ON(!pt->nr_pods);
+ return pt;
+}
+
/**
* init_worker_pool - initialize a newly zalloc'd worker_pool
* @pool: worker_pool to initialize
*/
static int init_worker_pool(struct worker_pool *pool)
{
- spin_lock_init(&pool->lock);
+ raw_spin_lock_init(&pool->lock);
pool->id = -1;
pool->cpu = -1;
pool->node = NUMA_NO_NODE;
hash_init(pool->busy_hash);
timer_setup(&pool->idle_timer, idle_worker_timeout, TIMER_DEFERRABLE);
+ INIT_WORK(&pool->idle_cull_work, idle_cull_fn);
timer_setup(&pool->mayday_timer, pool_mayday_timeout, 0);
INIT_LIST_HEAD(&pool->workers);
+ INIT_LIST_HEAD(&pool->dying_workers);
ida_init(&pool->worker_ida);
INIT_HLIST_NODE(&pool->hash_node);
pool->refcnt = 1;
/* shouldn't fail above this point */
- pool->attrs = alloc_workqueue_attrs(GFP_KERNEL);
+ pool->attrs = alloc_workqueue_attrs();
if (!pool->attrs)
return -ENOMEM;
+
+ wqattrs_clear_for_pool(pool->attrs);
+
return 0;
}
}
#endif
+static void free_node_nr_active(struct wq_node_nr_active **nna_ar)
+{
+ int node;
+
+ for_each_node(node) {
+ kfree(nna_ar[node]);
+ nna_ar[node] = NULL;
+ }
+
+ kfree(nna_ar[nr_node_ids]);
+ nna_ar[nr_node_ids] = NULL;
+}
+
+static void init_node_nr_active(struct wq_node_nr_active *nna)
+{
+ nna->max = WQ_DFL_MIN_ACTIVE;
+ atomic_set(&nna->nr, 0);
+ raw_spin_lock_init(&nna->lock);
+ INIT_LIST_HEAD(&nna->pending_pwqs);
+}
+
+/*
+ * Each node's nr_active counter will be accessed mostly from its own node and
+ * should be allocated in the node.
+ */
+static int alloc_node_nr_active(struct wq_node_nr_active **nna_ar)
+{
+ struct wq_node_nr_active *nna;
+ int node;
+
+ for_each_node(node) {
+ nna = kzalloc_node(sizeof(*nna), GFP_KERNEL, node);
+ if (!nna)
+ goto err_free;
+ init_node_nr_active(nna);
+ nna_ar[node] = nna;
+ }
+
+ /* [nr_node_ids] is used as the fallback */
+ nna = kzalloc_node(sizeof(*nna), GFP_KERNEL, NUMA_NO_NODE);
+ if (!nna)
+ goto err_free;
+ init_node_nr_active(nna);
+ nna_ar[nr_node_ids] = nna;
+
+ return 0;
+
+err_free:
+ free_node_nr_active(nna_ar);
+ return -ENOMEM;
+}
+
static void rcu_free_wq(struct rcu_head *rcu)
{
struct workqueue_struct *wq =
container_of(rcu, struct workqueue_struct, rcu);
- wq_free_lockdep(wq);
-
- if (!(wq->flags & WQ_UNBOUND))
- free_percpu(wq->cpu_pwqs);
- else
- free_workqueue_attrs(wq->unbound_attrs);
+ if (wq->flags & WQ_UNBOUND)
+ free_node_nr_active(wq->node_nr_active);
- kfree(wq->rescuer);
+ wq_free_lockdep(wq);
+ free_percpu(wq->cpu_pwq);
+ free_workqueue_attrs(wq->unbound_attrs);
kfree(wq);
}
{
DECLARE_COMPLETION_ONSTACK(detach_completion);
struct worker *worker;
+ LIST_HEAD(cull_list);
lockdep_assert_held(&wq_pool_mutex);
* Become the manager and destroy all workers. This prevents
* @pool's workers from blocking on attach_mutex. We're the last
* manager and @pool gets freed with the flag set.
+ *
+ * Having a concurrent manager is quite unlikely to happen as we can
+ * only get here with
+ * pwq->refcnt == pool->refcnt == 0
+ * which implies no work queued to the pool, which implies no worker can
+ * become the manager. However a worker could have taken the role of
+ * manager before the refcnts dropped to 0, since maybe_create_worker()
+ * drops pool->lock
*/
- spin_lock_irq(&pool->lock);
- wait_event_lock_irq(wq_manager_wait,
- !(pool->flags & POOL_MANAGER_ACTIVE), pool->lock);
- pool->flags |= POOL_MANAGER_ACTIVE;
+ while (true) {
+ rcuwait_wait_event(&manager_wait,
+ !(pool->flags & POOL_MANAGER_ACTIVE),
+ TASK_UNINTERRUPTIBLE);
+
+ mutex_lock(&wq_pool_attach_mutex);
+ raw_spin_lock_irq(&pool->lock);
+ if (!(pool->flags & POOL_MANAGER_ACTIVE)) {
+ pool->flags |= POOL_MANAGER_ACTIVE;
+ break;
+ }
+ raw_spin_unlock_irq(&pool->lock);
+ mutex_unlock(&wq_pool_attach_mutex);
+ }
while ((worker = first_idle_worker(pool)))
- destroy_worker(worker);
+ set_worker_dying(worker, &cull_list);
WARN_ON(pool->nr_workers || pool->nr_idle);
- spin_unlock_irq(&pool->lock);
+ raw_spin_unlock_irq(&pool->lock);
- mutex_lock(&wq_pool_attach_mutex);
- if (!list_empty(&pool->workers))
+ wake_dying_workers(&cull_list);
+
+ if (!list_empty(&pool->workers) || !list_empty(&pool->dying_workers))
pool->detach_completion = &detach_completion;
mutex_unlock(&wq_pool_attach_mutex);
/* shut down the timers */
del_timer_sync(&pool->idle_timer);
+ cancel_work_sync(&pool->idle_cull_work);
del_timer_sync(&pool->mayday_timer);
/* RCU protected to allow dereferences from get_work_pool() */
*/
static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs)
{
+ struct wq_pod_type *pt = &wq_pod_types[WQ_AFFN_NUMA];
u32 hash = wqattrs_hash(attrs);
struct worker_pool *pool;
- int node;
- int target_node = NUMA_NO_NODE;
+ int pod, node = NUMA_NO_NODE;
lockdep_assert_held(&wq_pool_mutex);
}
}
- /* if cpumask is contained inside a NUMA node, we belong to that node */
- if (wq_numa_enabled) {
- for_each_node(node) {
- if (cpumask_subset(attrs->cpumask,
- wq_numa_possible_cpumask[node])) {
- target_node = node;
- break;
- }
+ /* If __pod_cpumask is contained inside a NUMA pod, that's our node */
+ for (pod = 0; pod < pt->nr_pods; pod++) {
+ if (cpumask_subset(attrs->__pod_cpumask, pt->pod_cpus[pod])) {
+ node = pt->pod_node[pod];
+ break;
}
}
/* nope, create a new one */
- pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, target_node);
+ pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, node);
if (!pool || init_worker_pool(pool) < 0)
goto fail;
- lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */
+ pool->node = node;
copy_workqueue_attrs(pool->attrs, attrs);
- pool->node = target_node;
-
- /*
- * no_numa isn't a worker_pool attribute, always clear it. See
- * 'struct workqueue_attrs' comments for detail.
- */
- pool->attrs->no_numa = false;
+ wqattrs_clear_for_pool(pool->attrs);
if (worker_pool_assign_id(pool) < 0)
goto fail;
}
/*
- * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt
- * and needs to be destroyed.
+ * Scheduled on pwq_release_worker by put_pwq() when an unbound pwq hits zero
+ * refcnt and needs to be destroyed.
*/
-static void pwq_unbound_release_workfn(struct work_struct *work)
+static void pwq_release_workfn(struct kthread_work *work)
{
struct pool_workqueue *pwq = container_of(work, struct pool_workqueue,
- unbound_release_work);
+ release_work);
struct workqueue_struct *wq = pwq->wq;
struct worker_pool *pool = pwq->pool;
- bool is_last;
+ bool is_last = false;
- if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
- return;
+ /*
+ * When @pwq is not linked, it doesn't hold any reference to the
+ * @wq, and @wq is invalid to access.
+ */
+ if (!list_empty(&pwq->pwqs_node)) {
+ mutex_lock(&wq->mutex);
+ list_del_rcu(&pwq->pwqs_node);
+ is_last = list_empty(&wq->pwqs);
- mutex_lock(&wq->mutex);
- list_del_rcu(&pwq->pwqs_node);
- is_last = list_empty(&wq->pwqs);
- mutex_unlock(&wq->mutex);
+ /*
+ * For ordered workqueue with a plugged dfl_pwq, restart it now.
+ */
+ if (!is_last && (wq->flags & __WQ_ORDERED))
+ unplug_oldest_pwq(wq);
- mutex_lock(&wq_pool_mutex);
- put_unbound_pool(pool);
- mutex_unlock(&wq_pool_mutex);
+ mutex_unlock(&wq->mutex);
+ }
+
+ if (wq->flags & WQ_UNBOUND) {
+ mutex_lock(&wq_pool_mutex);
+ put_unbound_pool(pool);
+ mutex_unlock(&wq_pool_mutex);
+ }
+
+ if (!list_empty(&pwq->pending_node)) {
+ struct wq_node_nr_active *nna =
+ wq_node_nr_active(pwq->wq, pwq->pool->node);
+
+ raw_spin_lock_irq(&nna->lock);
+ list_del_init(&pwq->pending_node);
+ raw_spin_unlock_irq(&nna->lock);
+ }
call_rcu(&pwq->rcu, rcu_free_pwq);
}
}
-/**
- * pwq_adjust_max_active - update a pwq's max_active to the current setting
- * @pwq: target pool_workqueue
- *
- * If @pwq isn't freezing, set @pwq->max_active to the associated
- * workqueue's saved_max_active and activate delayed work items
- * accordingly. If @pwq is freezing, clear @pwq->max_active to zero.
- */
-static void pwq_adjust_max_active(struct pool_workqueue *pwq)
-{
- struct workqueue_struct *wq = pwq->wq;
- bool freezable = wq->flags & WQ_FREEZABLE;
- unsigned long flags;
-
- /* for @wq->saved_max_active */
- lockdep_assert_held(&wq->mutex);
-
- /* fast exit for non-freezable wqs */
- if (!freezable && pwq->max_active == wq->saved_max_active)
- return;
-
- /* this function can be called during early boot w/ irq disabled */
- spin_lock_irqsave(&pwq->pool->lock, flags);
-
- /*
- * During [un]freezing, the caller is responsible for ensuring that
- * this function is called at least once after @workqueue_freezing
- * is updated and visible.
- */
- if (!freezable || !workqueue_freezing) {
- pwq->max_active = wq->saved_max_active;
-
- while (!list_empty(&pwq->delayed_works) &&
- pwq->nr_active < pwq->max_active)
- pwq_activate_first_delayed(pwq);
-
- /*
- * Need to kick a worker after thawed or an unbound wq's
- * max_active is bumped. It's a slow path. Do it always.
- */
- wake_up_worker(pwq->pool);
- } else {
- pwq->max_active = 0;
- }
-
- spin_unlock_irqrestore(&pwq->pool->lock, flags);
-}
-
-/* initialize newly alloced @pwq which is associated with @wq and @pool */
+/* initialize newly allocated @pwq which is associated with @wq and @pool */
static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq,
struct worker_pool *pool)
{
- BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK);
+ BUG_ON((unsigned long)pwq & ~WORK_STRUCT_PWQ_MASK);
memset(pwq, 0, sizeof(*pwq));
pwq->wq = wq;
pwq->flush_color = -1;
pwq->refcnt = 1;
- INIT_LIST_HEAD(&pwq->delayed_works);
+ INIT_LIST_HEAD(&pwq->inactive_works);
+ INIT_LIST_HEAD(&pwq->pending_node);
INIT_LIST_HEAD(&pwq->pwqs_node);
INIT_LIST_HEAD(&pwq->mayday_node);
- INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn);
+ kthread_init_work(&pwq->release_work, pwq_release_workfn);
}
/* sync @pwq with the current state of its associated wq and link it */
/* set the matching work_color */
pwq->work_color = wq->work_color;
- /* sync max_active to the current setting */
- pwq_adjust_max_active(pwq);
-
/* link in @pwq */
- list_add_rcu(&pwq->pwqs_node, &wq->pwqs);
+ list_add_tail_rcu(&pwq->pwqs_node, &wq->pwqs);
}
/* obtain a pool matching @attr and create a pwq associating the pool and @wq */
}
/**
- * wq_calc_node_cpumask - calculate a wq_attrs' cpumask for the specified node
+ * wq_calc_pod_cpumask - calculate a wq_attrs' cpumask for a pod
* @attrs: the wq_attrs of the default pwq of the target workqueue
- * @node: the target NUMA node
+ * @cpu: the target CPU
* @cpu_going_down: if >= 0, the CPU to consider as offline
- * @cpumask: outarg, the resulting cpumask
*
- * Calculate the cpumask a workqueue with @attrs should use on @node. If
- * @cpu_going_down is >= 0, that cpu is considered offline during
- * calculation. The result is stored in @cpumask.
+ * Calculate the cpumask a workqueue with @attrs should use on @pod. If
+ * @cpu_going_down is >= 0, that cpu is considered offline during calculation.
+ * The result is stored in @attrs->__pod_cpumask.
*
- * If NUMA affinity is not enabled, @attrs->cpumask is always used. If
- * enabled and @node has online CPUs requested by @attrs, the returned
- * cpumask is the intersection of the possible CPUs of @node and
- * @attrs->cpumask.
+ * If pod affinity is not enabled, @attrs->cpumask is always used. If enabled
+ * and @pod has online CPUs requested by @attrs, the returned cpumask is the
+ * intersection of the possible CPUs of @pod and @attrs->cpumask.
*
- * The caller is responsible for ensuring that the cpumask of @node stays
- * stable.
- *
- * Return: %true if the resulting @cpumask is different from @attrs->cpumask,
- * %false if equal.
+ * The caller is responsible for ensuring that the cpumask of @pod stays stable.
*/
-static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node,
- int cpu_going_down, cpumask_t *cpumask)
+static void wq_calc_pod_cpumask(struct workqueue_attrs *attrs, int cpu,
+ int cpu_going_down)
{
- if (!wq_numa_enabled || attrs->no_numa)
- goto use_dfl;
+ const struct wq_pod_type *pt = wqattrs_pod_type(attrs);
+ int pod = pt->cpu_pod[cpu];
- /* does @node have any online CPUs @attrs wants? */
- cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask);
+ /* does @pod have any online CPUs @attrs wants? */
+ cpumask_and(attrs->__pod_cpumask, pt->pod_cpus[pod], attrs->cpumask);
+ cpumask_and(attrs->__pod_cpumask, attrs->__pod_cpumask, cpu_online_mask);
if (cpu_going_down >= 0)
- cpumask_clear_cpu(cpu_going_down, cpumask);
+ cpumask_clear_cpu(cpu_going_down, attrs->__pod_cpumask);
- if (cpumask_empty(cpumask))
- goto use_dfl;
+ if (cpumask_empty(attrs->__pod_cpumask)) {
+ cpumask_copy(attrs->__pod_cpumask, attrs->cpumask);
+ return;
+ }
- /* yeap, return possible CPUs in @node that @attrs wants */
- cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]);
+ /* yeap, return possible CPUs in @pod that @attrs wants */
+ cpumask_and(attrs->__pod_cpumask, attrs->cpumask, pt->pod_cpus[pod]);
- if (cpumask_empty(cpumask)) {
+ if (cpumask_empty(attrs->__pod_cpumask))
pr_warn_once("WARNING: workqueue cpumask: online intersect > "
"possible intersect\n");
- return false;
- }
-
- return !cpumask_equal(cpumask, attrs->cpumask);
-
-use_dfl:
- cpumask_copy(cpumask, attrs->cpumask);
- return false;
}
-/* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */
-static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq,
- int node,
- struct pool_workqueue *pwq)
+/* install @pwq into @wq and return the old pwq, @cpu < 0 for dfl_pwq */
+static struct pool_workqueue *install_unbound_pwq(struct workqueue_struct *wq,
+ int cpu, struct pool_workqueue *pwq)
{
+ struct pool_workqueue __rcu **slot = unbound_pwq_slot(wq, cpu);
struct pool_workqueue *old_pwq;
lockdep_assert_held(&wq_pool_mutex);
/* link_pwq() can handle duplicate calls */
link_pwq(pwq);
- old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
- rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq);
+ old_pwq = rcu_access_pointer(*slot);
+ rcu_assign_pointer(*slot, pwq);
return old_pwq;
}
static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx *ctx)
{
if (ctx) {
- int node;
+ int cpu;
- for_each_node(node)
- put_pwq_unlocked(ctx->pwq_tbl[node]);
+ for_each_possible_cpu(cpu)
+ put_pwq_unlocked(ctx->pwq_tbl[cpu]);
put_pwq_unlocked(ctx->dfl_pwq);
free_workqueue_attrs(ctx->attrs);
/* allocate the attrs and pwqs for later installation */
static struct apply_wqattrs_ctx *
apply_wqattrs_prepare(struct workqueue_struct *wq,
- const struct workqueue_attrs *attrs)
+ const struct workqueue_attrs *attrs,
+ const cpumask_var_t unbound_cpumask)
{
struct apply_wqattrs_ctx *ctx;
- struct workqueue_attrs *new_attrs, *tmp_attrs;
- int node;
+ struct workqueue_attrs *new_attrs;
+ int cpu;
lockdep_assert_held(&wq_pool_mutex);
- ctx = kzalloc(struct_size(ctx, pwq_tbl, nr_node_ids), GFP_KERNEL);
-
- new_attrs = alloc_workqueue_attrs(GFP_KERNEL);
- tmp_attrs = alloc_workqueue_attrs(GFP_KERNEL);
- if (!ctx || !new_attrs || !tmp_attrs)
- goto out_free;
+ if (WARN_ON(attrs->affn_scope < 0 ||
+ attrs->affn_scope >= WQ_AFFN_NR_TYPES))
+ return ERR_PTR(-EINVAL);
- /*
- * Calculate the attrs of the default pwq.
- * If the user configured cpumask doesn't overlap with the
- * wq_unbound_cpumask, we fallback to the wq_unbound_cpumask.
- */
- copy_workqueue_attrs(new_attrs, attrs);
- cpumask_and(new_attrs->cpumask, new_attrs->cpumask, wq_unbound_cpumask);
- if (unlikely(cpumask_empty(new_attrs->cpumask)))
- cpumask_copy(new_attrs->cpumask, wq_unbound_cpumask);
+ ctx = kzalloc(struct_size(ctx, pwq_tbl, nr_cpu_ids), GFP_KERNEL);
- /*
- * We may create multiple pwqs with differing cpumasks. Make a
- * copy of @new_attrs which will be modified and used to obtain
- * pools.
- */
- copy_workqueue_attrs(tmp_attrs, new_attrs);
+ new_attrs = alloc_workqueue_attrs();
+ if (!ctx || !new_attrs)
+ goto out_free;
/*
* If something goes wrong during CPU up/down, we'll fall back to
* the default pwq covering whole @attrs->cpumask. Always create
* it even if we don't use it immediately.
*/
+ copy_workqueue_attrs(new_attrs, attrs);
+ wqattrs_actualize_cpumask(new_attrs, unbound_cpumask);
+ cpumask_copy(new_attrs->__pod_cpumask, new_attrs->cpumask);
ctx->dfl_pwq = alloc_unbound_pwq(wq, new_attrs);
if (!ctx->dfl_pwq)
goto out_free;
- for_each_node(node) {
- if (wq_calc_node_cpumask(new_attrs, node, -1, tmp_attrs->cpumask)) {
- ctx->pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs);
- if (!ctx->pwq_tbl[node])
- goto out_free;
- } else {
+ for_each_possible_cpu(cpu) {
+ if (new_attrs->ordered) {
ctx->dfl_pwq->refcnt++;
- ctx->pwq_tbl[node] = ctx->dfl_pwq;
+ ctx->pwq_tbl[cpu] = ctx->dfl_pwq;
+ } else {
+ wq_calc_pod_cpumask(new_attrs, cpu, -1);
+ ctx->pwq_tbl[cpu] = alloc_unbound_pwq(wq, new_attrs);
+ if (!ctx->pwq_tbl[cpu])
+ goto out_free;
}
}
/* save the user configured attrs and sanitize it. */
copy_workqueue_attrs(new_attrs, attrs);
cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask);
+ cpumask_copy(new_attrs->__pod_cpumask, new_attrs->cpumask);
ctx->attrs = new_attrs;
+ /*
+ * For initialized ordered workqueues, there should only be one pwq
+ * (dfl_pwq). Set the plugged flag of ctx->dfl_pwq to suspend execution
+ * of newly queued work items until execution of older work items in
+ * the old pwq's have completed.
+ */
+ if ((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs))
+ ctx->dfl_pwq->plugged = true;
+
ctx->wq = wq;
- free_workqueue_attrs(tmp_attrs);
return ctx;
out_free:
- free_workqueue_attrs(tmp_attrs);
free_workqueue_attrs(new_attrs);
apply_wqattrs_cleanup(ctx);
- return NULL;
+ return ERR_PTR(-ENOMEM);
}
/* set attrs and install prepared pwqs, @ctx points to old pwqs on return */
static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx)
{
- int node;
+ int cpu;
/* all pwqs have been created successfully, let's install'em */
mutex_lock(&ctx->wq->mutex);
copy_workqueue_attrs(ctx->wq->unbound_attrs, ctx->attrs);
- /* save the previous pwq and install the new one */
- for_each_node(node)
- ctx->pwq_tbl[node] = numa_pwq_tbl_install(ctx->wq, node,
- ctx->pwq_tbl[node]);
-
- /* @dfl_pwq might not have been used, ensure it's linked */
- link_pwq(ctx->dfl_pwq);
- swap(ctx->wq->dfl_pwq, ctx->dfl_pwq);
+ /* save the previous pwqs and install the new ones */
+ for_each_possible_cpu(cpu)
+ ctx->pwq_tbl[cpu] = install_unbound_pwq(ctx->wq, cpu,
+ ctx->pwq_tbl[cpu]);
+ ctx->dfl_pwq = install_unbound_pwq(ctx->wq, -1, ctx->dfl_pwq);
- mutex_unlock(&ctx->wq->mutex);
-}
+ /* update node_nr_active->max */
+ wq_update_node_max_active(ctx->wq, -1);
-static void apply_wqattrs_lock(void)
-{
- /* CPUs should stay stable across pwq creations and installations */
- get_online_cpus();
- mutex_lock(&wq_pool_mutex);
-}
+ /* rescuer needs to respect wq cpumask changes */
+ if (ctx->wq->rescuer)
+ set_cpus_allowed_ptr(ctx->wq->rescuer->task,
+ unbound_effective_cpumask(ctx->wq));
-static void apply_wqattrs_unlock(void)
-{
- mutex_unlock(&wq_pool_mutex);
- put_online_cpus();
+ mutex_unlock(&ctx->wq->mutex);
}
static int apply_workqueue_attrs_locked(struct workqueue_struct *wq,
if (WARN_ON(!(wq->flags & WQ_UNBOUND)))
return -EINVAL;
- /* creating multiple pwqs breaks ordering guarantee */
- if (!list_empty(&wq->pwqs)) {
- if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT))
- return -EINVAL;
-
- wq->flags &= ~__WQ_ORDERED;
- }
-
- ctx = apply_wqattrs_prepare(wq, attrs);
- if (!ctx)
- return -ENOMEM;
+ ctx = apply_wqattrs_prepare(wq, attrs, wq_unbound_cpumask);
+ if (IS_ERR(ctx))
+ return PTR_ERR(ctx);
/* the ctx has been prepared successfully, let's commit it */
apply_wqattrs_commit(ctx);
* @wq: the target workqueue
* @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs()
*
- * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA
- * machines, this function maps a separate pwq to each NUMA node with
- * possibles CPUs in @attrs->cpumask so that work items are affine to the
- * NUMA node it was issued on. Older pwqs are released as in-flight work
- * items finish. Note that a work item which repeatedly requeues itself
- * back-to-back will stay on its current pwq.
+ * Apply @attrs to an unbound workqueue @wq. Unless disabled, this function maps
+ * a separate pwq to each CPU pod with possibles CPUs in @attrs->cpumask so that
+ * work items are affine to the pod it was issued on. Older pwqs are released as
+ * in-flight work items finish. Note that a work item which repeatedly requeues
+ * itself back-to-back will stay on its current pwq.
*
* Performs GFP_KERNEL allocations.
*
+ * Assumes caller has CPU hotplug read exclusion, i.e. cpus_read_lock().
+ *
* Return: 0 on success and -errno on failure.
*/
int apply_workqueue_attrs(struct workqueue_struct *wq,
{
int ret;
- apply_wqattrs_lock();
+ lockdep_assert_cpus_held();
+
+ mutex_lock(&wq_pool_mutex);
ret = apply_workqueue_attrs_locked(wq, attrs);
- apply_wqattrs_unlock();
+ mutex_unlock(&wq_pool_mutex);
return ret;
}
-EXPORT_SYMBOL_GPL(apply_workqueue_attrs);
/**
- * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug
+ * wq_update_pod - update pod affinity of a wq for CPU hot[un]plug
* @wq: the target workqueue
- * @cpu: the CPU coming up or going down
+ * @cpu: the CPU to update pool association for
+ * @hotplug_cpu: the CPU coming up or going down
* @online: whether @cpu is coming up or going down
*
* This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and
- * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of
+ * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update pod affinity of
* @wq accordingly.
*
- * If NUMA affinity can't be adjusted due to memory allocation failure, it
- * falls back to @wq->dfl_pwq which may not be optimal but is always
- * correct.
*
- * Note that when the last allowed CPU of a NUMA node goes offline for a
- * workqueue with a cpumask spanning multiple nodes, the workers which were
- * already executing the work items for the workqueue will lose their CPU
- * affinity and may execute on any CPU. This is similar to how per-cpu
- * workqueues behave on CPU_DOWN. If a workqueue user wants strict
- * affinity, it's the user's responsibility to flush the work item from
- * CPU_DOWN_PREPARE.
+ * If pod affinity can't be adjusted due to memory allocation failure, it falls
+ * back to @wq->dfl_pwq which may not be optimal but is always correct.
+ *
+ * Note that when the last allowed CPU of a pod goes offline for a workqueue
+ * with a cpumask spanning multiple pods, the workers which were already
+ * executing the work items for the workqueue will lose their CPU affinity and
+ * may execute on any CPU. This is similar to how per-cpu workqueues behave on
+ * CPU_DOWN. If a workqueue user wants strict affinity, it's the user's
+ * responsibility to flush the work item from CPU_DOWN_PREPARE.
*/
-static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
- bool online)
+static void wq_update_pod(struct workqueue_struct *wq, int cpu,
+ int hotplug_cpu, bool online)
{
- int node = cpu_to_node(cpu);
- int cpu_off = online ? -1 : cpu;
+ int off_cpu = online ? -1 : hotplug_cpu;
struct pool_workqueue *old_pwq = NULL, *pwq;
struct workqueue_attrs *target_attrs;
- cpumask_t *cpumask;
lockdep_assert_held(&wq_pool_mutex);
- if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND) ||
- wq->unbound_attrs->no_numa)
+ if (!(wq->flags & WQ_UNBOUND) || wq->unbound_attrs->ordered)
return;
/*
* Let's use a preallocated one. The following buf is protected by
* CPU hotplug exclusion.
*/
- target_attrs = wq_update_unbound_numa_attrs_buf;
- cpumask = target_attrs->cpumask;
+ target_attrs = wq_update_pod_attrs_buf;
copy_workqueue_attrs(target_attrs, wq->unbound_attrs);
- pwq = unbound_pwq_by_node(wq, node);
+ wqattrs_actualize_cpumask(target_attrs, wq_unbound_cpumask);
- /*
- * Let's determine what needs to be done. If the target cpumask is
- * different from the default pwq's, we need to compare it to @pwq's
- * and create a new one if they don't match. If the target cpumask
- * equals the default pwq's, the default pwq should be used.
- */
- if (wq_calc_node_cpumask(wq->dfl_pwq->pool->attrs, node, cpu_off, cpumask)) {
- if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask))
- return;
- } else {
- goto use_dfl_pwq;
- }
+ /* nothing to do if the target cpumask matches the current pwq */
+ wq_calc_pod_cpumask(target_attrs, cpu, off_cpu);
+ if (wqattrs_equal(target_attrs, unbound_pwq(wq, cpu)->pool->attrs))
+ return;
/* create a new pwq */
pwq = alloc_unbound_pwq(wq, target_attrs);
if (!pwq) {
- pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",
+ pr_warn("workqueue: allocation failed while updating CPU pod affinity of \"%s\"\n",
wq->name);
goto use_dfl_pwq;
}
/* Install the new pwq. */
mutex_lock(&wq->mutex);
- old_pwq = numa_pwq_tbl_install(wq, node, pwq);
+ old_pwq = install_unbound_pwq(wq, cpu, pwq);
goto out_unlock;
use_dfl_pwq:
mutex_lock(&wq->mutex);
- spin_lock_irq(&wq->dfl_pwq->pool->lock);
- get_pwq(wq->dfl_pwq);
- spin_unlock_irq(&wq->dfl_pwq->pool->lock);
- old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq);
+ pwq = unbound_pwq(wq, -1);
+ raw_spin_lock_irq(&pwq->pool->lock);
+ get_pwq(pwq);
+ raw_spin_unlock_irq(&pwq->pool->lock);
+ old_pwq = install_unbound_pwq(wq, cpu, pwq);
out_unlock:
mutex_unlock(&wq->mutex);
put_pwq_unlocked(old_pwq);
bool highpri = wq->flags & WQ_HIGHPRI;
int cpu, ret;
- if (!(wq->flags & WQ_UNBOUND)) {
- wq->cpu_pwqs = alloc_percpu(struct pool_workqueue);
- if (!wq->cpu_pwqs)
- return -ENOMEM;
+ wq->cpu_pwq = alloc_percpu(struct pool_workqueue *);
+ if (!wq->cpu_pwq)
+ goto enomem;
+ if (!(wq->flags & WQ_UNBOUND)) {
for_each_possible_cpu(cpu) {
- struct pool_workqueue *pwq =
- per_cpu_ptr(wq->cpu_pwqs, cpu);
- struct worker_pool *cpu_pools =
- per_cpu(cpu_worker_pools, cpu);
+ struct pool_workqueue **pwq_p;
+ struct worker_pool __percpu *pools;
+ struct worker_pool *pool;
+
+ if (wq->flags & WQ_BH)
+ pools = bh_worker_pools;
+ else
+ pools = cpu_worker_pools;
+
+ pool = &(per_cpu_ptr(pools, cpu)[highpri]);
+ pwq_p = per_cpu_ptr(wq->cpu_pwq, cpu);
- init_pwq(pwq, wq, &cpu_pools[highpri]);
+ *pwq_p = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL,
+ pool->node);
+ if (!*pwq_p)
+ goto enomem;
+
+ init_pwq(*pwq_p, wq, pool);
mutex_lock(&wq->mutex);
- link_pwq(pwq);
+ link_pwq(*pwq_p);
mutex_unlock(&wq->mutex);
}
return 0;
- } else if (wq->flags & __WQ_ORDERED) {
+ }
+
+ cpus_read_lock();
+ if (wq->flags & __WQ_ORDERED) {
+ struct pool_workqueue *dfl_pwq;
+
ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]);
/* there should only be single pwq for ordering guarantee */
- WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node ||
- wq->pwqs.prev != &wq->dfl_pwq->pwqs_node),
+ dfl_pwq = rcu_access_pointer(wq->dfl_pwq);
+ WARN(!ret && (wq->pwqs.next != &dfl_pwq->pwqs_node ||
+ wq->pwqs.prev != &dfl_pwq->pwqs_node),
"ordering guarantee broken for workqueue %s\n", wq->name);
- return ret;
} else {
- return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]);
+ ret = apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]);
+ }
+ cpus_read_unlock();
+
+ /* for unbound pwq, flush the pwq_release_worker ensures that the
+ * pwq_release_workfn() completes before calling kfree(wq).
+ */
+ if (ret)
+ kthread_flush_worker(pwq_release_worker);
+
+ return ret;
+
+enomem:
+ if (wq->cpu_pwq) {
+ for_each_possible_cpu(cpu) {
+ struct pool_workqueue *pwq = *per_cpu_ptr(wq->cpu_pwq, cpu);
+
+ if (pwq)
+ kmem_cache_free(pwq_cache, pwq);
+ }
+ free_percpu(wq->cpu_pwq);
+ wq->cpu_pwq = NULL;
}
+ return -ENOMEM;
}
static int wq_clamp_max_active(int max_active, unsigned int flags,
const char *name)
{
- int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE;
-
- if (max_active < 1 || max_active > lim)
+ if (max_active < 1 || max_active > WQ_MAX_ACTIVE)
pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",
- max_active, name, 1, lim);
+ max_active, name, 1, WQ_MAX_ACTIVE);
- return clamp_val(max_active, 1, lim);
+ return clamp_val(max_active, 1, WQ_MAX_ACTIVE);
}
/*
return 0;
rescuer = alloc_worker(NUMA_NO_NODE);
- if (!rescuer)
+ if (!rescuer) {
+ pr_err("workqueue: Failed to allocate a rescuer for wq \"%s\"\n",
+ wq->name);
return -ENOMEM;
+ }
rescuer->rescue_wq = wq;
- rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", wq->name);
- ret = PTR_ERR_OR_ZERO(rescuer->task);
- if (ret) {
+ rescuer->task = kthread_create(rescuer_thread, rescuer, "kworker/R-%s", wq->name);
+ if (IS_ERR(rescuer->task)) {
+ ret = PTR_ERR(rescuer->task);
+ pr_err("workqueue: Failed to create a rescuer kthread for wq \"%s\": %pe",
+ wq->name, ERR_PTR(ret));
kfree(rescuer);
return ret;
}
wq->rescuer = rescuer;
- kthread_bind_mask(rescuer->task, cpu_possible_mask);
+ if (wq->flags & WQ_UNBOUND)
+ kthread_bind_mask(rescuer->task, wq_unbound_cpumask);
+ else
+ kthread_bind_mask(rescuer->task, cpu_possible_mask);
wake_up_process(rescuer->task);
return 0;
}
+/**
+ * wq_adjust_max_active - update a wq's max_active to the current setting
+ * @wq: target workqueue
+ *
+ * If @wq isn't freezing, set @wq->max_active to the saved_max_active and
+ * activate inactive work items accordingly. If @wq is freezing, clear
+ * @wq->max_active to zero.
+ */
+static void wq_adjust_max_active(struct workqueue_struct *wq)
+{
+ bool activated;
+ int new_max, new_min;
+
+ lockdep_assert_held(&wq->mutex);
+
+ if ((wq->flags & WQ_FREEZABLE) && workqueue_freezing) {
+ new_max = 0;
+ new_min = 0;
+ } else {
+ new_max = wq->saved_max_active;
+ new_min = wq->saved_min_active;
+ }
+
+ if (wq->max_active == new_max && wq->min_active == new_min)
+ return;
+
+ /*
+ * Update @wq->max/min_active and then kick inactive work items if more
+ * active work items are allowed. This doesn't break work item ordering
+ * because new work items are always queued behind existing inactive
+ * work items if there are any.
+ */
+ WRITE_ONCE(wq->max_active, new_max);
+ WRITE_ONCE(wq->min_active, new_min);
+
+ if (wq->flags & WQ_UNBOUND)
+ wq_update_node_max_active(wq, -1);
+
+ if (new_max == 0)
+ return;
+
+ /*
+ * Round-robin through pwq's activating the first inactive work item
+ * until max_active is filled.
+ */
+ do {
+ struct pool_workqueue *pwq;
+
+ activated = false;
+ for_each_pwq(pwq, wq) {
+ unsigned long irq_flags;
+
+ /* can be called during early boot w/ irq disabled */
+ raw_spin_lock_irqsave(&pwq->pool->lock, irq_flags);
+ if (pwq_activate_first_inactive(pwq, true)) {
+ activated = true;
+ kick_pool(pwq->pool);
+ }
+ raw_spin_unlock_irqrestore(&pwq->pool->lock, irq_flags);
+ }
+ } while (activated);
+}
+
__printf(1, 4)
struct workqueue_struct *alloc_workqueue(const char *fmt,
unsigned int flags,
int max_active, ...)
{
- size_t tbl_size = 0;
va_list args;
struct workqueue_struct *wq;
- struct pool_workqueue *pwq;
-
- /*
- * Unbound && max_active == 1 used to imply ordered, which is no
- * longer the case on NUMA machines due to per-node pools. While
- * alloc_ordered_workqueue() is the right way to create an ordered
- * workqueue, keep the previous behavior to avoid subtle breakages
- * on NUMA.
- */
- if ((flags & WQ_UNBOUND) && max_active == 1)
- flags |= __WQ_ORDERED;
+ size_t wq_size;
+ int name_len;
+
+ if (flags & WQ_BH) {
+ if (WARN_ON_ONCE(flags & ~__WQ_BH_ALLOWS))
+ return NULL;
+ if (WARN_ON_ONCE(max_active))
+ return NULL;
+ }
/* see the comment above the definition of WQ_POWER_EFFICIENT */
if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
/* allocate wq and format name */
if (flags & WQ_UNBOUND)
- tbl_size = nr_node_ids * sizeof(wq->numa_pwq_tbl[0]);
+ wq_size = struct_size(wq, node_nr_active, nr_node_ids + 1);
+ else
+ wq_size = sizeof(*wq);
- wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL);
+ wq = kzalloc(wq_size, GFP_KERNEL);
if (!wq)
return NULL;
if (flags & WQ_UNBOUND) {
- wq->unbound_attrs = alloc_workqueue_attrs(GFP_KERNEL);
+ wq->unbound_attrs = alloc_workqueue_attrs();
if (!wq->unbound_attrs)
goto err_free_wq;
}
va_start(args, max_active);
- vsnprintf(wq->name, sizeof(wq->name), fmt, args);
+ name_len = vsnprintf(wq->name, sizeof(wq->name), fmt, args);
va_end(args);
- max_active = max_active ?: WQ_DFL_ACTIVE;
- max_active = wq_clamp_max_active(max_active, flags, wq->name);
+ if (name_len >= WQ_NAME_LEN)
+ pr_warn_once("workqueue: name exceeds WQ_NAME_LEN. Truncating to: %s\n",
+ wq->name);
+
+ if (flags & WQ_BH) {
+ /*
+ * BH workqueues always share a single execution context per CPU
+ * and don't impose any max_active limit.
+ */
+ max_active = INT_MAX;
+ } else {
+ max_active = max_active ?: WQ_DFL_ACTIVE;
+ max_active = wq_clamp_max_active(max_active, flags, wq->name);
+ }
/* init wq */
wq->flags = flags;
- wq->saved_max_active = max_active;
+ wq->max_active = max_active;
+ wq->min_active = min(max_active, WQ_DFL_MIN_ACTIVE);
+ wq->saved_max_active = wq->max_active;
+ wq->saved_min_active = wq->min_active;
mutex_init(&wq->mutex);
atomic_set(&wq->nr_pwqs_to_flush, 0);
INIT_LIST_HEAD(&wq->pwqs);
wq_init_lockdep(wq);
INIT_LIST_HEAD(&wq->list);
+ if (flags & WQ_UNBOUND) {
+ if (alloc_node_nr_active(wq->node_nr_active) < 0)
+ goto err_unreg_lockdep;
+ }
+
if (alloc_and_link_pwqs(wq) < 0)
- goto err_unreg_lockdep;
+ goto err_free_node_nr_active;
if (wq_online && init_rescuer(wq) < 0)
goto err_destroy;
mutex_lock(&wq_pool_mutex);
mutex_lock(&wq->mutex);
- for_each_pwq(pwq, wq)
- pwq_adjust_max_active(pwq);
+ wq_adjust_max_active(wq);
mutex_unlock(&wq->mutex);
list_add_tail_rcu(&wq->list, &workqueues);
return wq;
+err_free_node_nr_active:
+ if (wq->flags & WQ_UNBOUND)
+ free_node_nr_active(wq->node_nr_active);
err_unreg_lockdep:
wq_unregister_lockdep(wq);
wq_free_lockdep(wq);
destroy_workqueue(wq);
return NULL;
}
-EXPORT_SYMBOL_GPL(alloc_workqueue);
+EXPORT_SYMBOL_GPL(alloc_workqueue);
+
+static bool pwq_busy(struct pool_workqueue *pwq)
+{
+ int i;
+
+ for (i = 0; i < WORK_NR_COLORS; i++)
+ if (pwq->nr_in_flight[i])
+ return true;
+
+ if ((pwq != rcu_access_pointer(pwq->wq->dfl_pwq)) && (pwq->refcnt > 1))
+ return true;
+ if (!pwq_is_empty(pwq))
+ return true;
+
+ return false;
+}
/**
* destroy_workqueue - safely terminate a workqueue
void destroy_workqueue(struct workqueue_struct *wq)
{
struct pool_workqueue *pwq;
- int node;
+ int cpu;
+
+ /*
+ * Remove it from sysfs first so that sanity check failure doesn't
+ * lead to sysfs name conflicts.
+ */
+ workqueue_sysfs_unregister(wq);
+
+ /* mark the workqueue destruction is in progress */
+ mutex_lock(&wq->mutex);
+ wq->flags |= __WQ_DESTROYING;
+ mutex_unlock(&wq->mutex);
/* drain it before proceeding with destruction */
drain_workqueue(wq);
- /* sanity checks */
- mutex_lock(&wq->mutex);
- for_each_pwq(pwq, wq) {
- int i;
+ /* kill rescuer, if sanity checks fail, leave it w/o rescuer */
+ if (wq->rescuer) {
+ struct worker *rescuer = wq->rescuer;
- for (i = 0; i < WORK_NR_COLORS; i++) {
- if (WARN_ON(pwq->nr_in_flight[i])) {
- mutex_unlock(&wq->mutex);
- show_workqueue_state();
- return;
- }
- }
+ /* this prevents new queueing */
+ raw_spin_lock_irq(&wq_mayday_lock);
+ wq->rescuer = NULL;
+ raw_spin_unlock_irq(&wq_mayday_lock);
+
+ /* rescuer will empty maydays list before exiting */
+ kthread_stop(rescuer->task);
+ kfree(rescuer);
+ }
- if (WARN_ON((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) ||
- WARN_ON(pwq->nr_active) ||
- WARN_ON(!list_empty(&pwq->delayed_works))) {
+ /*
+ * Sanity checks - grab all the locks so that we wait for all
+ * in-flight operations which may do put_pwq().
+ */
+ mutex_lock(&wq_pool_mutex);
+ mutex_lock(&wq->mutex);
+ for_each_pwq(pwq, wq) {
+ raw_spin_lock_irq(&pwq->pool->lock);
+ if (WARN_ON(pwq_busy(pwq))) {
+ pr_warn("%s: %s has the following busy pwq\n",
+ __func__, wq->name);
+ show_pwq(pwq);
+ raw_spin_unlock_irq(&pwq->pool->lock);
mutex_unlock(&wq->mutex);
- show_workqueue_state();
+ mutex_unlock(&wq_pool_mutex);
+ show_one_workqueue(wq);
return;
}
+ raw_spin_unlock_irq(&pwq->pool->lock);
}
mutex_unlock(&wq->mutex);
* wq list is used to freeze wq, remove from list after
* flushing is complete in case freeze races us.
*/
- mutex_lock(&wq_pool_mutex);
list_del_rcu(&wq->list);
mutex_unlock(&wq_pool_mutex);
- workqueue_sysfs_unregister(wq);
+ /*
+ * We're the sole accessor of @wq. Directly access cpu_pwq and dfl_pwq
+ * to put the base refs. @wq will be auto-destroyed from the last
+ * pwq_put. RCU read lock prevents @wq from going away from under us.
+ */
+ rcu_read_lock();
- if (wq->rescuer)
- kthread_stop(wq->rescuer->task);
+ for_each_possible_cpu(cpu) {
+ put_pwq_unlocked(unbound_pwq(wq, cpu));
+ RCU_INIT_POINTER(*unbound_pwq_slot(wq, cpu), NULL);
+ }
- if (!(wq->flags & WQ_UNBOUND)) {
- wq_unregister_lockdep(wq);
- /*
- * The base ref is never dropped on per-cpu pwqs. Directly
- * schedule RCU free.
- */
- call_rcu(&wq->rcu, rcu_free_wq);
- } else {
- /*
- * We're the sole accessor of @wq at this point. Directly
- * access numa_pwq_tbl[] and dfl_pwq to put the base refs.
- * @wq will be freed when the last pwq is released.
- */
- for_each_node(node) {
- pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
- RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL);
- put_pwq_unlocked(pwq);
- }
+ put_pwq_unlocked(unbound_pwq(wq, -1));
+ RCU_INIT_POINTER(*unbound_pwq_slot(wq, -1), NULL);
- /*
- * Put dfl_pwq. @wq may be freed any time after dfl_pwq is
- * put. Don't access it afterwards.
- */
- pwq = wq->dfl_pwq;
- wq->dfl_pwq = NULL;
- put_pwq_unlocked(pwq);
- }
+ rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(destroy_workqueue);
* @wq: target workqueue
* @max_active: new max_active value.
*
- * Set max_active of @wq to @max_active.
+ * Set max_active of @wq to @max_active. See the alloc_workqueue() function
+ * comment.
*
* CONTEXT:
* Don't call from IRQ context.
*/
void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
{
- struct pool_workqueue *pwq;
-
+ /* max_active doesn't mean anything for BH workqueues */
+ if (WARN_ON(wq->flags & WQ_BH))
+ return;
/* disallow meddling with max_active for ordered workqueues */
- if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT))
+ if (WARN_ON(wq->flags & __WQ_ORDERED))
return;
max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
mutex_lock(&wq->mutex);
- wq->flags &= ~__WQ_ORDERED;
wq->saved_max_active = max_active;
+ if (wq->flags & WQ_UNBOUND)
+ wq->saved_min_active = min(wq->saved_min_active, max_active);
- for_each_pwq(pwq, wq)
- pwq_adjust_max_active(pwq);
+ wq_adjust_max_active(wq);
mutex_unlock(&wq->mutex);
}
EXPORT_SYMBOL_GPL(workqueue_set_max_active);
+/**
+ * workqueue_set_min_active - adjust min_active of an unbound workqueue
+ * @wq: target unbound workqueue
+ * @min_active: new min_active value
+ *
+ * Set min_active of an unbound workqueue. Unlike other types of workqueues, an
+ * unbound workqueue is not guaranteed to be able to process max_active
+ * interdependent work items. Instead, an unbound workqueue is guaranteed to be
+ * able to process min_active number of interdependent work items which is
+ * %WQ_DFL_MIN_ACTIVE by default.
+ *
+ * Use this function to adjust the min_active value between 0 and the current
+ * max_active.
+ */
+void workqueue_set_min_active(struct workqueue_struct *wq, int min_active)
+{
+ /* min_active is only meaningful for non-ordered unbound workqueues */
+ if (WARN_ON((wq->flags & (WQ_BH | WQ_UNBOUND | __WQ_ORDERED)) !=
+ WQ_UNBOUND))
+ return;
+
+ mutex_lock(&wq->mutex);
+ wq->saved_min_active = clamp(min_active, 0, wq->saved_max_active);
+ wq_adjust_max_active(wq);
+ mutex_unlock(&wq->mutex);
+}
+
/**
* current_work - retrieve %current task's work struct
*
* unreliable and only useful as advisory hints or for debugging.
*
* If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU.
- * Note that both per-cpu and unbound workqueues may be associated with
- * multiple pool_workqueues which have separate congested states. A
- * workqueue being congested on one CPU doesn't mean the workqueue is also
- * contested on other CPUs / NUMA nodes.
+ *
+ * With the exception of ordered workqueues, all workqueues have per-cpu
+ * pool_workqueues, each with its own congested state. A workqueue being
+ * congested on one CPU doesn't mean that the workqueue is contested on any
+ * other CPUs.
*
* Return:
* %true if congested, %false otherwise.
if (cpu == WORK_CPU_UNBOUND)
cpu = smp_processor_id();
- if (!(wq->flags & WQ_UNBOUND))
- pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
- else
- pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
+ pwq = *per_cpu_ptr(wq->cpu_pwq, cpu);
+ ret = !list_empty(&pwq->inactive_works);
- ret = !list_empty(&pwq->delayed_works);
preempt_enable();
rcu_read_unlock();
unsigned int work_busy(struct work_struct *work)
{
struct worker_pool *pool;
- unsigned long flags;
+ unsigned long irq_flags;
unsigned int ret = 0;
if (work_pending(work))
rcu_read_lock();
pool = get_work_pool(work);
if (pool) {
- spin_lock_irqsave(&pool->lock, flags);
+ raw_spin_lock_irqsave(&pool->lock, irq_flags);
if (find_worker_executing_work(pool, work))
ret |= WORK_BUSY_RUNNING;
- spin_unlock_irqrestore(&pool->lock, flags);
+ raw_spin_unlock_irqrestore(&pool->lock, irq_flags);
}
rcu_read_unlock();
* Carefully copy the associated workqueue's workfn, name and desc.
* Keep the original last '\0' in case the original is garbage.
*/
- probe_kernel_read(&fn, &worker->current_func, sizeof(fn));
- probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq));
- probe_kernel_read(&wq, &pwq->wq, sizeof(wq));
- probe_kernel_read(name, wq->name, sizeof(name) - 1);
- probe_kernel_read(desc, worker->desc, sizeof(desc) - 1);
+ copy_from_kernel_nofault(&fn, &worker->current_func, sizeof(fn));
+ copy_from_kernel_nofault(&pwq, &worker->current_pwq, sizeof(pwq));
+ copy_from_kernel_nofault(&wq, &pwq->wq, sizeof(wq));
+ copy_from_kernel_nofault(name, wq->name, sizeof(name) - 1);
+ copy_from_kernel_nofault(desc, worker->desc, sizeof(desc) - 1);
if (fn || name[0] || desc[0]) {
printk("%sWorkqueue: %s %ps", log_lvl, name, fn);
pr_cont(" cpus=%*pbl", nr_cpumask_bits, pool->attrs->cpumask);
if (pool->node != NUMA_NO_NODE)
pr_cont(" node=%d", pool->node);
- pr_cont(" flags=0x%x nice=%d", pool->flags, pool->attrs->nice);
+ pr_cont(" flags=0x%x", pool->flags);
+ if (pool->flags & POOL_BH)
+ pr_cont(" bh%s",
+ pool->attrs->nice == HIGHPRI_NICE_LEVEL ? "-hi" : "");
+ else
+ pr_cont(" nice=%d", pool->attrs->nice);
+}
+
+static void pr_cont_worker_id(struct worker *worker)
+{
+ struct worker_pool *pool = worker->pool;
+
+ if (pool->flags & WQ_BH)
+ pr_cont("bh%s",
+ pool->attrs->nice == HIGHPRI_NICE_LEVEL ? "-hi" : "");
+ else
+ pr_cont("%d%s", task_pid_nr(worker->task),
+ worker->rescue_wq ? "(RESCUER)" : "");
+}
+
+struct pr_cont_work_struct {
+ bool comma;
+ work_func_t func;
+ long ctr;
+};
+
+static void pr_cont_work_flush(bool comma, work_func_t func, struct pr_cont_work_struct *pcwsp)
+{
+ if (!pcwsp->ctr)
+ goto out_record;
+ if (func == pcwsp->func) {
+ pcwsp->ctr++;
+ return;
+ }
+ if (pcwsp->ctr == 1)
+ pr_cont("%s %ps", pcwsp->comma ? "," : "", pcwsp->func);
+ else
+ pr_cont("%s %ld*%ps", pcwsp->comma ? "," : "", pcwsp->ctr, pcwsp->func);
+ pcwsp->ctr = 0;
+out_record:
+ if ((long)func == -1L)
+ return;
+ pcwsp->comma = comma;
+ pcwsp->func = func;
+ pcwsp->ctr = 1;
}
-static void pr_cont_work(bool comma, struct work_struct *work)
+static void pr_cont_work(bool comma, struct work_struct *work, struct pr_cont_work_struct *pcwsp)
{
if (work->func == wq_barrier_func) {
struct wq_barrier *barr;
barr = container_of(work, struct wq_barrier, work);
+ pr_cont_work_flush(comma, (work_func_t)-1, pcwsp);
pr_cont("%s BAR(%d)", comma ? "," : "",
task_pid_nr(barr->task));
} else {
- pr_cont("%s %ps", comma ? "," : "", work->func);
+ if (!comma)
+ pr_cont_work_flush(comma, (work_func_t)-1, pcwsp);
+ pr_cont_work_flush(comma, work->func, pcwsp);
}
}
static void show_pwq(struct pool_workqueue *pwq)
{
+ struct pr_cont_work_struct pcws = { .ctr = 0, };
struct worker_pool *pool = pwq->pool;
struct work_struct *work;
struct worker *worker;
pr_info(" pwq %d:", pool->id);
pr_cont_pool_info(pool);
- pr_cont(" active=%d/%d%s\n", pwq->nr_active, pwq->max_active,
+ pr_cont(" active=%d refcnt=%d%s\n",
+ pwq->nr_active, pwq->refcnt,
!list_empty(&pwq->mayday_node) ? " MAYDAY" : "");
hash_for_each(pool->busy_hash, bkt, worker, hentry) {
if (worker->current_pwq != pwq)
continue;
- pr_cont("%s %d%s:%ps", comma ? "," : "",
- task_pid_nr(worker->task),
- worker == pwq->wq->rescuer ? "(RESCUER)" : "",
- worker->current_func);
+ pr_cont(" %s", comma ? "," : "");
+ pr_cont_worker_id(worker);
+ pr_cont(":%ps", worker->current_func);
list_for_each_entry(work, &worker->scheduled, entry)
- pr_cont_work(false, work);
+ pr_cont_work(false, work, &pcws);
+ pr_cont_work_flush(comma, (work_func_t)-1L, &pcws);
comma = true;
}
pr_cont("\n");
if (get_work_pwq(work) != pwq)
continue;
- pr_cont_work(comma, work);
+ pr_cont_work(comma, work, &pcws);
comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED);
}
+ pr_cont_work_flush(comma, (work_func_t)-1L, &pcws);
pr_cont("\n");
}
- if (!list_empty(&pwq->delayed_works)) {
+ if (!list_empty(&pwq->inactive_works)) {
bool comma = false;
- pr_info(" delayed:");
- list_for_each_entry(work, &pwq->delayed_works, entry) {
- pr_cont_work(comma, work);
+ pr_info(" inactive:");
+ list_for_each_entry(work, &pwq->inactive_works, entry) {
+ pr_cont_work(comma, work, &pcws);
comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED);
}
+ pr_cont_work_flush(comma, (work_func_t)-1L, &pcws);
pr_cont("\n");
}
}
/**
- * show_workqueue_state - dump workqueue state
+ * show_one_workqueue - dump state of specified workqueue
+ * @wq: workqueue whose state will be printed
+ */
+void show_one_workqueue(struct workqueue_struct *wq)
+{
+ struct pool_workqueue *pwq;
+ bool idle = true;
+ unsigned long irq_flags;
+
+ for_each_pwq(pwq, wq) {
+ if (!pwq_is_empty(pwq)) {
+ idle = false;
+ break;
+ }
+ }
+ if (idle) /* Nothing to print for idle workqueue */
+ return;
+
+ pr_info("workqueue %s: flags=0x%x\n", wq->name, wq->flags);
+
+ for_each_pwq(pwq, wq) {
+ raw_spin_lock_irqsave(&pwq->pool->lock, irq_flags);
+ if (!pwq_is_empty(pwq)) {
+ /*
+ * Defer printing to avoid deadlocks in console
+ * drivers that queue work while holding locks
+ * also taken in their write paths.
+ */
+ printk_deferred_enter();
+ show_pwq(pwq);
+ printk_deferred_exit();
+ }
+ raw_spin_unlock_irqrestore(&pwq->pool->lock, irq_flags);
+ /*
+ * We could be printing a lot from atomic context, e.g.
+ * sysrq-t -> show_all_workqueues(). Avoid triggering
+ * hard lockup.
+ */
+ touch_nmi_watchdog();
+ }
+
+}
+
+/**
+ * show_one_worker_pool - dump state of specified worker pool
+ * @pool: worker pool whose state will be printed
+ */
+static void show_one_worker_pool(struct worker_pool *pool)
+{
+ struct worker *worker;
+ bool first = true;
+ unsigned long irq_flags;
+ unsigned long hung = 0;
+
+ raw_spin_lock_irqsave(&pool->lock, irq_flags);
+ if (pool->nr_workers == pool->nr_idle)
+ goto next_pool;
+
+ /* How long the first pending work is waiting for a worker. */
+ if (!list_empty(&pool->worklist))
+ hung = jiffies_to_msecs(jiffies - pool->watchdog_ts) / 1000;
+
+ /*
+ * Defer printing to avoid deadlocks in console drivers that
+ * queue work while holding locks also taken in their write
+ * paths.
+ */
+ printk_deferred_enter();
+ pr_info("pool %d:", pool->id);
+ pr_cont_pool_info(pool);
+ pr_cont(" hung=%lus workers=%d", hung, pool->nr_workers);
+ if (pool->manager)
+ pr_cont(" manager: %d",
+ task_pid_nr(pool->manager->task));
+ list_for_each_entry(worker, &pool->idle_list, entry) {
+ pr_cont(" %s", first ? "idle: " : "");
+ pr_cont_worker_id(worker);
+ first = false;
+ }
+ pr_cont("\n");
+ printk_deferred_exit();
+next_pool:
+ raw_spin_unlock_irqrestore(&pool->lock, irq_flags);
+ /*
+ * We could be printing a lot from atomic context, e.g.
+ * sysrq-t -> show_all_workqueues(). Avoid triggering
+ * hard lockup.
+ */
+ touch_nmi_watchdog();
+
+}
+
+/**
+ * show_all_workqueues - dump workqueue state
*
- * Called from a sysrq handler or try_to_freeze_tasks() and prints out
- * all busy workqueues and pools.
+ * Called from a sysrq handler and prints out all busy workqueues and pools.
*/
-void show_workqueue_state(void)
+void show_all_workqueues(void)
{
struct workqueue_struct *wq;
struct worker_pool *pool;
- unsigned long flags;
int pi;
rcu_read_lock();
pr_info("Showing busy workqueues and worker pools:\n");
- list_for_each_entry_rcu(wq, &workqueues, list) {
- struct pool_workqueue *pwq;
- bool idle = true;
+ list_for_each_entry_rcu(wq, &workqueues, list)
+ show_one_workqueue(wq);
- for_each_pwq(pwq, wq) {
- if (pwq->nr_active || !list_empty(&pwq->delayed_works)) {
- idle = false;
- break;
- }
- }
- if (idle)
- continue;
+ for_each_pool(pool, pi)
+ show_one_worker_pool(pool);
- pr_info("workqueue %s: flags=0x%x\n", wq->name, wq->flags);
+ rcu_read_unlock();
+}
- for_each_pwq(pwq, wq) {
- spin_lock_irqsave(&pwq->pool->lock, flags);
- if (pwq->nr_active || !list_empty(&pwq->delayed_works))
- show_pwq(pwq);
- spin_unlock_irqrestore(&pwq->pool->lock, flags);
- /*
- * We could be printing a lot from atomic context, e.g.
- * sysrq-t -> show_workqueue_state(). Avoid triggering
- * hard lockup.
- */
- touch_nmi_watchdog();
- }
- }
+/**
+ * show_freezable_workqueues - dump freezable workqueue state
+ *
+ * Called from try_to_freeze_tasks() and prints out all freezable workqueues
+ * still busy.
+ */
+void show_freezable_workqueues(void)
+{
+ struct workqueue_struct *wq;
- for_each_pool(pool, pi) {
- struct worker *worker;
- bool first = true;
-
- spin_lock_irqsave(&pool->lock, flags);
- if (pool->nr_workers == pool->nr_idle)
- goto next_pool;
-
- pr_info("pool %d:", pool->id);
- pr_cont_pool_info(pool);
- pr_cont(" hung=%us workers=%d",
- jiffies_to_msecs(jiffies - pool->watchdog_ts) / 1000,
- pool->nr_workers);
- if (pool->manager)
- pr_cont(" manager: %d",
- task_pid_nr(pool->manager->task));
- list_for_each_entry(worker, &pool->idle_list, entry) {
- pr_cont(" %s%d", first ? "idle: " : "",
- task_pid_nr(worker->task));
- first = false;
- }
- pr_cont("\n");
- next_pool:
- spin_unlock_irqrestore(&pool->lock, flags);
- /*
- * We could be printing a lot from atomic context, e.g.
- * sysrq-t -> show_workqueue_state(). Avoid triggering
- * hard lockup.
- */
- touch_nmi_watchdog();
+ rcu_read_lock();
+
+ pr_info("Showing freezable workqueues that are still busy:\n");
+
+ list_for_each_entry_rcu(wq, &workqueues, list) {
+ if (!(wq->flags & WQ_FREEZABLE))
+ continue;
+ show_one_workqueue(wq);
}
rcu_read_unlock();
struct worker_pool *pool = worker->pool;
if (pool) {
- spin_lock_irq(&pool->lock);
+ raw_spin_lock_irq(&pool->lock);
/*
* ->desc tracks information (wq name or
* set_worker_desc()) for the latest execution. If
scnprintf(buf + off, size - off, "-%s",
worker->desc);
}
- spin_unlock_irq(&pool->lock);
+ raw_spin_unlock_irq(&pool->lock);
}
}
for_each_cpu_worker_pool(pool, cpu) {
mutex_lock(&wq_pool_attach_mutex);
- spin_lock_irq(&pool->lock);
+ raw_spin_lock_irq(&pool->lock);
/*
* We've blocked all attach/detach operations. Make all workers
* unbound and set DISASSOCIATED. Before this, all workers
- * except for the ones which are still executing works from
- * before the last CPU down must be on the cpu. After
- * this, they may become diasporas.
+ * must be on the cpu. After this, they may become diasporas.
+ * And the preemption disabled section in their sched callbacks
+ * are guaranteed to see WORKER_UNBOUND since the code here
+ * is on the same cpu.
*/
for_each_pool_worker(worker, pool)
worker->flags |= WORKER_UNBOUND;
pool->flags |= POOL_DISASSOCIATED;
- spin_unlock_irq(&pool->lock);
- mutex_unlock(&wq_pool_attach_mutex);
-
- /*
- * Call schedule() so that we cross rq->lock and thus can
- * guarantee sched callbacks see the %WORKER_UNBOUND flag.
- * This is necessary as scheduler callbacks may be invoked
- * from other cpus.
- */
- schedule();
-
/*
- * Sched callbacks are disabled now. Zap nr_running.
- * After this, nr_running stays zero and need_more_worker()
- * and keep_working() are always true as long as the
- * worklist is not empty. This pool now behaves as an
- * unbound (in terms of concurrency management) pool which
+ * The handling of nr_running in sched callbacks are disabled
+ * now. Zap nr_running. After this, nr_running stays zero and
+ * need_more_worker() and keep_working() are always true as
+ * long as the worklist is not empty. This pool now behaves as
+ * an unbound (in terms of concurrency management) pool which
* are served by workers tied to the pool.
*/
- atomic_set(&pool->nr_running, 0);
+ pool->nr_running = 0;
/*
* With concurrency management just turned off, a busy
* worker blocking could lead to lengthy stalls. Kick off
* unbound chain execution of currently pending work items.
*/
- spin_lock_irq(&pool->lock);
- wake_up_worker(pool);
- spin_unlock_irq(&pool->lock);
+ kick_pool(pool);
+
+ raw_spin_unlock_irq(&pool->lock);
+
+ for_each_pool_worker(worker, pool)
+ unbind_worker(worker);
+
+ mutex_unlock(&wq_pool_attach_mutex);
}
}
* of all workers first and then clear UNBOUND. As we're called
* from CPU_ONLINE, the following shouldn't fail.
*/
- for_each_pool_worker(worker, pool)
+ for_each_pool_worker(worker, pool) {
+ kthread_set_per_cpu(worker->task, pool->cpu);
WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
- pool->attrs->cpumask) < 0);
+ pool_allowed_cpus(pool)) < 0);
+ }
- spin_lock_irq(&pool->lock);
+ raw_spin_lock_irq(&pool->lock);
pool->flags &= ~POOL_DISASSOCIATED;
for_each_pool_worker(worker, pool) {
unsigned int worker_flags = worker->flags;
- /*
- * A bound idle worker should actually be on the runqueue
- * of the associated CPU for local wake-ups targeting it to
- * work. Kick all idle workers so that they migrate to the
- * associated CPU. Doing this in the same loop as
- * replacing UNBOUND with REBOUND is safe as no worker will
- * be bound before @pool->lock is released.
- */
- if (worker_flags & WORKER_IDLE)
- wake_up_process(worker->task);
-
/*
* We want to clear UNBOUND but can't directly call
* worker_clr_flags() or adjust nr_running. Atomically
WRITE_ONCE(worker->flags, worker_flags);
}
- spin_unlock_irq(&pool->lock);
+ raw_spin_unlock_irq(&pool->lock);
}
/**
mutex_lock(&wq_pool_mutex);
for_each_pool(pool, pi) {
- mutex_lock(&wq_pool_attach_mutex);
+ /* BH pools aren't affected by hotplug */
+ if (pool->flags & POOL_BH)
+ continue;
+ mutex_lock(&wq_pool_attach_mutex);
if (pool->cpu == cpu)
rebind_workers(pool);
else if (pool->cpu < 0)
restore_unbound_workers_cpumask(pool, cpu);
-
mutex_unlock(&wq_pool_attach_mutex);
}
- /* update NUMA affinity of unbound workqueues */
- list_for_each_entry(wq, &workqueues, list)
- wq_update_unbound_numa(wq, cpu, true);
+ /* update pod affinity of unbound workqueues */
+ list_for_each_entry(wq, &workqueues, list) {
+ struct workqueue_attrs *attrs = wq->unbound_attrs;
+
+ if (attrs) {
+ const struct wq_pod_type *pt = wqattrs_pod_type(attrs);
+ int tcpu;
+
+ for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]])
+ wq_update_pod(wq, tcpu, cpu, true);
+
+ mutex_lock(&wq->mutex);
+ wq_update_node_max_active(wq, -1);
+ mutex_unlock(&wq->mutex);
+ }
+ }
mutex_unlock(&wq_pool_mutex);
return 0;
unbind_workers(cpu);
- /* update NUMA affinity of unbound workqueues */
+ /* update pod affinity of unbound workqueues */
mutex_lock(&wq_pool_mutex);
- list_for_each_entry(wq, &workqueues, list)
- wq_update_unbound_numa(wq, cpu, false);
+ list_for_each_entry(wq, &workqueues, list) {
+ struct workqueue_attrs *attrs = wq->unbound_attrs;
+
+ if (attrs) {
+ const struct wq_pod_type *pt = wqattrs_pod_type(attrs);
+ int tcpu;
+
+ for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]])
+ wq_update_pod(wq, tcpu, cpu, false);
+
+ mutex_lock(&wq->mutex);
+ wq_update_node_max_active(wq, cpu);
+ mutex_unlock(&wq->mutex);
+ }
+ }
mutex_unlock(&wq_pool_mutex);
return 0;
}
/**
- * work_on_cpu - run a function in thread context on a particular cpu
+ * work_on_cpu_key - run a function in thread context on a particular cpu
* @cpu: the cpu to run on
* @fn: the function to run
* @arg: the function arg
+ * @key: The lock class key for lock debugging purposes
*
* It is up to the caller to ensure that the cpu doesn't go offline.
* The caller must not hold any locks which would prevent @fn from completing.
*
* Return: The value @fn returns.
*/
-long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
+long work_on_cpu_key(int cpu, long (*fn)(void *),
+ void *arg, struct lock_class_key *key)
{
struct work_for_cpu wfc = { .fn = fn, .arg = arg };
- INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn);
+ INIT_WORK_ONSTACK_KEY(&wfc.work, work_for_cpu_fn, key);
schedule_work_on(cpu, &wfc.work);
flush_work(&wfc.work);
destroy_work_on_stack(&wfc.work);
return wfc.ret;
}
-EXPORT_SYMBOL_GPL(work_on_cpu);
+EXPORT_SYMBOL_GPL(work_on_cpu_key);
/**
- * work_on_cpu_safe - run a function in thread context on a particular cpu
+ * work_on_cpu_safe_key - run a function in thread context on a particular cpu
* @cpu: the cpu to run on
* @fn: the function to run
* @arg: the function argument
+ * @key: The lock class key for lock debugging purposes
*
* Disables CPU hotplug and calls work_on_cpu(). The caller must not hold
* any locks which would prevent @fn from completing.
*
* Return: The value @fn returns.
*/
-long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg)
+long work_on_cpu_safe_key(int cpu, long (*fn)(void *),
+ void *arg, struct lock_class_key *key)
{
long ret = -ENODEV;
- get_online_cpus();
+ cpus_read_lock();
if (cpu_online(cpu))
- ret = work_on_cpu(cpu, fn, arg);
- put_online_cpus();
+ ret = work_on_cpu_key(cpu, fn, arg, key);
+ cpus_read_unlock();
return ret;
}
-EXPORT_SYMBOL_GPL(work_on_cpu_safe);
+EXPORT_SYMBOL_GPL(work_on_cpu_safe_key);
#endif /* CONFIG_SMP */
#ifdef CONFIG_FREEZER
* freeze_workqueues_begin - begin freezing workqueues
*
* Start freezing workqueues. After this function returns, all freezable
- * workqueues will queue new works to their delayed_works list instead of
+ * workqueues will queue new works to their inactive_works list instead of
* pool->worklist.
*
* CONTEXT:
void freeze_workqueues_begin(void)
{
struct workqueue_struct *wq;
- struct pool_workqueue *pwq;
mutex_lock(&wq_pool_mutex);
list_for_each_entry(wq, &workqueues, list) {
mutex_lock(&wq->mutex);
- for_each_pwq(pwq, wq)
- pwq_adjust_max_active(pwq);
+ wq_adjust_max_active(wq);
mutex_unlock(&wq->mutex);
}
void thaw_workqueues(void)
{
struct workqueue_struct *wq;
- struct pool_workqueue *pwq;
mutex_lock(&wq_pool_mutex);
/* restore max_active and repopulate worklist */
list_for_each_entry(wq, &workqueues, list) {
mutex_lock(&wq->mutex);
- for_each_pwq(pwq, wq)
- pwq_adjust_max_active(pwq);
+ wq_adjust_max_active(wq);
mutex_unlock(&wq->mutex);
}
}
#endif /* CONFIG_FREEZER */
-static int workqueue_apply_unbound_cpumask(void)
+static int workqueue_apply_unbound_cpumask(const cpumask_var_t unbound_cpumask)
{
LIST_HEAD(ctxs);
int ret = 0;
lockdep_assert_held(&wq_pool_mutex);
list_for_each_entry(wq, &workqueues, list) {
- if (!(wq->flags & WQ_UNBOUND))
- continue;
- /* creating multiple pwqs breaks ordering guarantee */
- if (wq->flags & __WQ_ORDERED)
+ if (!(wq->flags & WQ_UNBOUND) || (wq->flags & __WQ_DESTROYING))
continue;
- ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs);
- if (!ctx) {
- ret = -ENOMEM;
+ ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs, unbound_cpumask);
+ if (IS_ERR(ctx)) {
+ ret = PTR_ERR(ctx);
break;
}
apply_wqattrs_cleanup(ctx);
}
+ if (!ret) {
+ mutex_lock(&wq_pool_attach_mutex);
+ cpumask_copy(wq_unbound_cpumask, unbound_cpumask);
+ mutex_unlock(&wq_pool_attach_mutex);
+ }
return ret;
}
/**
- * workqueue_set_unbound_cpumask - Set the low-level unbound cpumask
- * @cpumask: the cpumask to set
- *
- * The low-level workqueues cpumask is a global cpumask that limits
- * the affinity of all unbound workqueues. This function check the @cpumask
- * and apply it to all unbound workqueues and updates all pwqs of them.
+ * workqueue_unbound_exclude_cpumask - Exclude given CPUs from unbound cpumask
+ * @exclude_cpumask: the cpumask to be excluded from wq_unbound_cpumask
*
- * Retun: 0 - Success
- * -EINVAL - Invalid @cpumask
- * -ENOMEM - Failed to allocate memory for attrs or pwqs.
+ * This function can be called from cpuset code to provide a set of isolated
+ * CPUs that should be excluded from wq_unbound_cpumask. The caller must hold
+ * either cpus_read_lock or cpus_write_lock.
*/
-int workqueue_set_unbound_cpumask(cpumask_var_t cpumask)
+int workqueue_unbound_exclude_cpumask(cpumask_var_t exclude_cpumask)
{
- int ret = -EINVAL;
- cpumask_var_t saved_cpumask;
+ cpumask_var_t cpumask;
+ int ret = 0;
- if (!zalloc_cpumask_var(&saved_cpumask, GFP_KERNEL))
+ if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL))
return -ENOMEM;
+ lockdep_assert_cpus_held();
+ mutex_lock(&wq_pool_mutex);
+
+ /* Save the current isolated cpumask & export it via sysfs */
+ cpumask_copy(wq_isolated_cpumask, exclude_cpumask);
+
/*
- * Not excluding isolated cpus on purpose.
- * If the user wishes to include them, we allow that.
+ * If the operation fails, it will fall back to
+ * wq_requested_unbound_cpumask which is initially set to
+ * (HK_TYPE_WQ ∩ HK_TYPE_DOMAIN) house keeping mask and rewritten
+ * by any subsequent write to workqueue/cpumask sysfs file.
*/
- cpumask_and(cpumask, cpumask, cpu_possible_mask);
- if (!cpumask_empty(cpumask)) {
- apply_wqattrs_lock();
+ if (!cpumask_andnot(cpumask, wq_requested_unbound_cpumask, exclude_cpumask))
+ cpumask_copy(cpumask, wq_requested_unbound_cpumask);
+ if (!cpumask_equal(cpumask, wq_unbound_cpumask))
+ ret = workqueue_apply_unbound_cpumask(cpumask);
+
+ mutex_unlock(&wq_pool_mutex);
+ free_cpumask_var(cpumask);
+ return ret;
+}
+
+static int parse_affn_scope(const char *val)
+{
+ int i;
- /* save the old wq_unbound_cpumask. */
- cpumask_copy(saved_cpumask, wq_unbound_cpumask);
+ for (i = 0; i < ARRAY_SIZE(wq_affn_names); i++) {
+ if (!strncasecmp(val, wq_affn_names[i], strlen(wq_affn_names[i])))
+ return i;
+ }
+ return -EINVAL;
+}
- /* update wq_unbound_cpumask at first and apply it to wqs. */
- cpumask_copy(wq_unbound_cpumask, cpumask);
- ret = workqueue_apply_unbound_cpumask();
+static int wq_affn_dfl_set(const char *val, const struct kernel_param *kp)
+{
+ struct workqueue_struct *wq;
+ int affn, cpu;
- /* restore the wq_unbound_cpumask when failed. */
- if (ret < 0)
- cpumask_copy(wq_unbound_cpumask, saved_cpumask);
+ affn = parse_affn_scope(val);
+ if (affn < 0)
+ return affn;
+ if (affn == WQ_AFFN_DFL)
+ return -EINVAL;
- apply_wqattrs_unlock();
+ cpus_read_lock();
+ mutex_lock(&wq_pool_mutex);
+
+ wq_affn_dfl = affn;
+
+ list_for_each_entry(wq, &workqueues, list) {
+ for_each_online_cpu(cpu) {
+ wq_update_pod(wq, cpu, cpu, true);
+ }
}
- free_cpumask_var(saved_cpumask);
- return ret;
+ mutex_unlock(&wq_pool_mutex);
+ cpus_read_unlock();
+
+ return 0;
}
+static int wq_affn_dfl_get(char *buffer, const struct kernel_param *kp)
+{
+ return scnprintf(buffer, PAGE_SIZE, "%s\n", wq_affn_names[wq_affn_dfl]);
+}
+
+static const struct kernel_param_ops wq_affn_dfl_ops = {
+ .set = wq_affn_dfl_set,
+ .get = wq_affn_dfl_get,
+};
+
+module_param_cb(default_affinity_scope, &wq_affn_dfl_ops, NULL, 0644);
+
#ifdef CONFIG_SYSFS
/*
* Workqueues with WQ_SYSFS flag set is visible to userland via
* /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the
* following attributes.
*
- * per_cpu RO bool : whether the workqueue is per-cpu or unbound
- * max_active RW int : maximum number of in-flight work items
+ * per_cpu RO bool : whether the workqueue is per-cpu or unbound
+ * max_active RW int : maximum number of in-flight work items
*
* Unbound workqueues have the following extra attributes.
*
- * pool_ids RO int : the associated pool IDs for each node
- * nice RW int : nice value of the workers
- * cpumask RW mask : bitmask of allowed CPUs for the workers
- * numa RW bool : whether enable NUMA affinity
+ * nice RW int : nice value of the workers
+ * cpumask RW mask : bitmask of allowed CPUs for the workers
+ * affinity_scope RW str : worker CPU affinity scope (cache, numa, none)
+ * affinity_strict RW bool : worker CPU affinity is strict
*/
struct wq_device {
struct workqueue_struct *wq;
};
ATTRIBUTE_GROUPS(wq_sysfs);
-static ssize_t wq_pool_ids_show(struct device *dev,
- struct device_attribute *attr, char *buf)
+static void apply_wqattrs_lock(void)
{
- struct workqueue_struct *wq = dev_to_wq(dev);
- const char *delim = "";
- int node, written = 0;
-
- get_online_cpus();
- rcu_read_lock();
- for_each_node(node) {
- written += scnprintf(buf + written, PAGE_SIZE - written,
- "%s%d:%d", delim, node,
- unbound_pwq_by_node(wq, node)->pool->id);
- delim = " ";
- }
- written += scnprintf(buf + written, PAGE_SIZE - written, "\n");
- rcu_read_unlock();
- put_online_cpus();
+ /* CPUs should stay stable across pwq creations and installations */
+ cpus_read_lock();
+ mutex_lock(&wq_pool_mutex);
+}
- return written;
+static void apply_wqattrs_unlock(void)
+{
+ mutex_unlock(&wq_pool_mutex);
+ cpus_read_unlock();
}
static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr,
lockdep_assert_held(&wq_pool_mutex);
- attrs = alloc_workqueue_attrs(GFP_KERNEL);
+ attrs = alloc_workqueue_attrs();
if (!attrs)
return NULL;
return ret ?: count;
}
-static ssize_t wq_numa_show(struct device *dev, struct device_attribute *attr,
- char *buf)
+static ssize_t wq_affn_scope_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
{
struct workqueue_struct *wq = dev_to_wq(dev);
int written;
mutex_lock(&wq->mutex);
- written = scnprintf(buf, PAGE_SIZE, "%d\n",
- !wq->unbound_attrs->no_numa);
+ if (wq->unbound_attrs->affn_scope == WQ_AFFN_DFL)
+ written = scnprintf(buf, PAGE_SIZE, "%s (%s)\n",
+ wq_affn_names[WQ_AFFN_DFL],
+ wq_affn_names[wq_affn_dfl]);
+ else
+ written = scnprintf(buf, PAGE_SIZE, "%s\n",
+ wq_affn_names[wq->unbound_attrs->affn_scope]);
mutex_unlock(&wq->mutex);
return written;
}
-static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr,
- const char *buf, size_t count)
+static ssize_t wq_affn_scope_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
{
struct workqueue_struct *wq = dev_to_wq(dev);
struct workqueue_attrs *attrs;
- int v, ret = -ENOMEM;
+ int affn, ret = -ENOMEM;
- apply_wqattrs_lock();
+ affn = parse_affn_scope(buf);
+ if (affn < 0)
+ return affn;
+ apply_wqattrs_lock();
attrs = wq_sysfs_prep_attrs(wq);
- if (!attrs)
- goto out_unlock;
-
- ret = -EINVAL;
- if (sscanf(buf, "%d", &v) == 1) {
- attrs->no_numa = !v;
+ if (attrs) {
+ attrs->affn_scope = affn;
ret = apply_workqueue_attrs_locked(wq, attrs);
}
+ apply_wqattrs_unlock();
+ free_workqueue_attrs(attrs);
+ return ret ?: count;
+}
-out_unlock:
+static ssize_t wq_affinity_strict_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct workqueue_struct *wq = dev_to_wq(dev);
+
+ return scnprintf(buf, PAGE_SIZE, "%d\n",
+ wq->unbound_attrs->affn_strict);
+}
+
+static ssize_t wq_affinity_strict_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct workqueue_struct *wq = dev_to_wq(dev);
+ struct workqueue_attrs *attrs;
+ int v, ret = -ENOMEM;
+
+ if (sscanf(buf, "%d", &v) != 1)
+ return -EINVAL;
+
+ apply_wqattrs_lock();
+ attrs = wq_sysfs_prep_attrs(wq);
+ if (attrs) {
+ attrs->affn_strict = (bool)v;
+ ret = apply_workqueue_attrs_locked(wq, attrs);
+ }
apply_wqattrs_unlock();
free_workqueue_attrs(attrs);
return ret ?: count;
}
static struct device_attribute wq_sysfs_unbound_attrs[] = {
- __ATTR(pool_ids, 0444, wq_pool_ids_show, NULL),
__ATTR(nice, 0644, wq_nice_show, wq_nice_store),
__ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store),
- __ATTR(numa, 0644, wq_numa_show, wq_numa_store),
+ __ATTR(affinity_scope, 0644, wq_affn_scope_show, wq_affn_scope_store),
+ __ATTR(affinity_strict, 0644, wq_affinity_strict_show, wq_affinity_strict_store),
__ATTR_NULL,
};
-static struct bus_type wq_subsys = {
+static const struct bus_type wq_subsys = {
.name = "workqueue",
.dev_groups = wq_sysfs_groups,
};
-static ssize_t wq_unbound_cpumask_show(struct device *dev,
- struct device_attribute *attr, char *buf)
+/**
+ * workqueue_set_unbound_cpumask - Set the low-level unbound cpumask
+ * @cpumask: the cpumask to set
+ *
+ * The low-level workqueues cpumask is a global cpumask that limits
+ * the affinity of all unbound workqueues. This function check the @cpumask
+ * and apply it to all unbound workqueues and updates all pwqs of them.
+ *
+ * Return: 0 - Success
+ * -EINVAL - Invalid @cpumask
+ * -ENOMEM - Failed to allocate memory for attrs or pwqs.
+ */
+static int workqueue_set_unbound_cpumask(cpumask_var_t cpumask)
+{
+ int ret = -EINVAL;
+
+ /*
+ * Not excluding isolated cpus on purpose.
+ * If the user wishes to include them, we allow that.
+ */
+ cpumask_and(cpumask, cpumask, cpu_possible_mask);
+ if (!cpumask_empty(cpumask)) {
+ apply_wqattrs_lock();
+ cpumask_copy(wq_requested_unbound_cpumask, cpumask);
+ if (cpumask_equal(cpumask, wq_unbound_cpumask)) {
+ ret = 0;
+ goto out_unlock;
+ }
+
+ ret = workqueue_apply_unbound_cpumask(cpumask);
+
+out_unlock:
+ apply_wqattrs_unlock();
+ }
+
+ return ret;
+}
+
+static ssize_t __wq_cpumask_show(struct device *dev,
+ struct device_attribute *attr, char *buf, cpumask_var_t mask)
{
int written;
mutex_lock(&wq_pool_mutex);
- written = scnprintf(buf, PAGE_SIZE, "%*pb\n",
- cpumask_pr_args(wq_unbound_cpumask));
+ written = scnprintf(buf, PAGE_SIZE, "%*pb\n", cpumask_pr_args(mask));
mutex_unlock(&wq_pool_mutex);
return written;
}
+static ssize_t wq_unbound_cpumask_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return __wq_cpumask_show(dev, attr, buf, wq_unbound_cpumask);
+}
+
+static ssize_t wq_requested_cpumask_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return __wq_cpumask_show(dev, attr, buf, wq_requested_unbound_cpumask);
+}
+
+static ssize_t wq_isolated_cpumask_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return __wq_cpumask_show(dev, attr, buf, wq_isolated_cpumask);
+}
+
static ssize_t wq_unbound_cpumask_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
return ret ? ret : count;
}
-static struct device_attribute wq_sysfs_cpumask_attr =
+static struct device_attribute wq_sysfs_cpumask_attrs[] = {
__ATTR(cpumask, 0644, wq_unbound_cpumask_show,
- wq_unbound_cpumask_store);
+ wq_unbound_cpumask_store),
+ __ATTR(cpumask_requested, 0444, wq_requested_cpumask_show, NULL),
+ __ATTR(cpumask_isolated, 0444, wq_isolated_cpumask_show, NULL),
+ __ATTR_NULL,
+};
static int __init wq_sysfs_init(void)
{
+ struct device *dev_root;
int err;
err = subsys_virtual_register(&wq_subsys, NULL);
if (err)
return err;
- return device_create_file(wq_subsys.dev_root, &wq_sysfs_cpumask_attr);
+ dev_root = bus_get_dev_root(&wq_subsys);
+ if (dev_root) {
+ struct device_attribute *attr;
+
+ for (attr = wq_sysfs_cpumask_attrs; attr->attr.name; attr++) {
+ err = device_create_file(dev_root, attr);
+ if (err)
+ break;
+ }
+ put_device(dev_root);
+ }
+ return err;
}
core_initcall(wq_sysfs_init);
int ret;
/*
- * Adjusting max_active or creating new pwqs by applying
- * attributes breaks ordering guarantee. Disallow exposing ordered
- * workqueues.
+ * Adjusting max_active breaks ordering guarantee. Disallow exposing
+ * ordered workqueues.
*/
- if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT))
+ if (WARN_ON(wq->flags & __WQ_ORDERED))
return -EINVAL;
wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL);
static unsigned long wq_watchdog_touched = INITIAL_JIFFIES;
static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES;
+/*
+ * Show workers that might prevent the processing of pending work items.
+ * The only candidates are CPU-bound workers in the running state.
+ * Pending work items should be handled by another idle worker
+ * in all other situations.
+ */
+static void show_cpu_pool_hog(struct worker_pool *pool)
+{
+ struct worker *worker;
+ unsigned long irq_flags;
+ int bkt;
+
+ raw_spin_lock_irqsave(&pool->lock, irq_flags);
+
+ hash_for_each(pool->busy_hash, bkt, worker, hentry) {
+ if (task_is_running(worker->task)) {
+ /*
+ * Defer printing to avoid deadlocks in console
+ * drivers that queue work while holding locks
+ * also taken in their write paths.
+ */
+ printk_deferred_enter();
+
+ pr_info("pool %d:\n", pool->id);
+ sched_show_task(worker->task);
+
+ printk_deferred_exit();
+ }
+ }
+
+ raw_spin_unlock_irqrestore(&pool->lock, irq_flags);
+}
+
+static void show_cpu_pools_hogs(void)
+{
+ struct worker_pool *pool;
+ int pi;
+
+ pr_info("Showing backtraces of running workers in stalled CPU-bound worker pools:\n");
+
+ rcu_read_lock();
+
+ for_each_pool(pool, pi) {
+ if (pool->cpu_stall)
+ show_cpu_pool_hog(pool);
+
+ }
+
+ rcu_read_unlock();
+}
+
static void wq_watchdog_reset_touched(void)
{
int cpu;
{
unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ;
bool lockup_detected = false;
+ bool cpu_pool_stall = false;
+ unsigned long now = jiffies;
struct worker_pool *pool;
int pi;
for_each_pool(pool, pi) {
unsigned long pool_ts, touched, ts;
+ pool->cpu_stall = false;
if (list_empty(&pool->worklist))
continue;
+ /*
+ * If a virtual machine is stopped by the host it can look to
+ * the watchdog like a stall.
+ */
+ kvm_check_and_clear_guest_paused();
+
/* get the latest of pool and touched timestamps */
+ if (pool->cpu >= 0)
+ touched = READ_ONCE(per_cpu(wq_watchdog_touched_cpu, pool->cpu));
+ else
+ touched = READ_ONCE(wq_watchdog_touched);
pool_ts = READ_ONCE(pool->watchdog_ts);
- touched = READ_ONCE(wq_watchdog_touched);
if (time_after(pool_ts, touched))
ts = pool_ts;
else
ts = touched;
- if (pool->cpu >= 0) {
- unsigned long cpu_touched =
- READ_ONCE(per_cpu(wq_watchdog_touched_cpu,
- pool->cpu));
- if (time_after(cpu_touched, ts))
- ts = cpu_touched;
- }
-
/* did we stall? */
- if (time_after(jiffies, ts + thresh)) {
+ if (time_after(now, ts + thresh)) {
lockup_detected = true;
+ if (pool->cpu >= 0 && !(pool->flags & POOL_BH)) {
+ pool->cpu_stall = true;
+ cpu_pool_stall = true;
+ }
pr_emerg("BUG: workqueue lockup - pool");
pr_cont_pool_info(pool);
pr_cont(" stuck for %us!\n",
- jiffies_to_msecs(jiffies - pool_ts) / 1000);
+ jiffies_to_msecs(now - pool_ts) / 1000);
}
+
+
}
rcu_read_unlock();
if (lockup_detected)
- show_workqueue_state();
+ show_all_workqueues();
+
+ if (cpu_pool_stall)
+ show_cpu_pools_hogs();
wq_watchdog_reset_touched();
mod_timer(&wq_watchdog_timer, jiffies + thresh);
{
if (cpu >= 0)
per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies;
- else
- wq_watchdog_touched = jiffies;
+
+ wq_watchdog_touched = jiffies;
}
static void wq_watchdog_set_thresh(unsigned long thresh)
#endif /* CONFIG_WQ_WATCHDOG */
-static void __init wq_numa_init(void)
+static void bh_pool_kick_normal(struct irq_work *irq_work)
{
- cpumask_var_t *tbl;
- int node, cpu;
+ raise_softirq_irqoff(TASKLET_SOFTIRQ);
+}
- if (num_possible_nodes() <= 1)
- return;
+static void bh_pool_kick_highpri(struct irq_work *irq_work)
+{
+ raise_softirq_irqoff(HI_SOFTIRQ);
+}
- if (wq_disable_numa) {
- pr_info("workqueue: NUMA affinity support disabled\n");
+static void __init restrict_unbound_cpumask(const char *name, const struct cpumask *mask)
+{
+ if (!cpumask_intersects(wq_unbound_cpumask, mask)) {
+ pr_warn("workqueue: Restricting unbound_cpumask (%*pb) with %s (%*pb) leaves no CPU, ignoring\n",
+ cpumask_pr_args(wq_unbound_cpumask), name, cpumask_pr_args(mask));
return;
}
- wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs(GFP_KERNEL);
- BUG_ON(!wq_update_unbound_numa_attrs_buf);
-
- /*
- * We want masks of possible CPUs of each node which isn't readily
- * available. Build one from cpu_to_node() which should have been
- * fully initialized by now.
- */
- tbl = kcalloc(nr_node_ids, sizeof(tbl[0]), GFP_KERNEL);
- BUG_ON(!tbl);
-
- for_each_node(node)
- BUG_ON(!zalloc_cpumask_var_node(&tbl[node], GFP_KERNEL,
- node_online(node) ? node : NUMA_NO_NODE));
+ cpumask_and(wq_unbound_cpumask, wq_unbound_cpumask, mask);
+}
- for_each_possible_cpu(cpu) {
- node = cpu_to_node(cpu);
- if (WARN_ON(node == NUMA_NO_NODE)) {
- pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu);
- /* happens iff arch is bonkers, let's just proceed */
- return;
- }
- cpumask_set_cpu(cpu, tbl[node]);
- }
+static void __init init_cpu_worker_pool(struct worker_pool *pool, int cpu, int nice)
+{
+ BUG_ON(init_worker_pool(pool));
+ pool->cpu = cpu;
+ cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu));
+ cpumask_copy(pool->attrs->__pod_cpumask, cpumask_of(cpu));
+ pool->attrs->nice = nice;
+ pool->attrs->affn_strict = true;
+ pool->node = cpu_to_node(cpu);
- wq_numa_possible_cpumask = tbl;
- wq_numa_enabled = true;
+ /* alloc pool ID */
+ mutex_lock(&wq_pool_mutex);
+ BUG_ON(worker_pool_assign_id(pool));
+ mutex_unlock(&wq_pool_mutex);
}
/**
* workqueue_init_early - early init for workqueue subsystem
*
- * This is the first half of two-staged workqueue subsystem initialization
- * and invoked as soon as the bare basics - memory allocation, cpumasks and
- * idr are up. It sets up all the data structures and system workqueues
- * and allows early boot code to create workqueues and queue/cancel work
- * items. Actual work item execution starts only after kthreads can be
- * created and scheduled right before early initcalls.
+ * This is the first step of three-staged workqueue subsystem initialization and
+ * invoked as soon as the bare basics - memory allocation, cpumasks and idr are
+ * up. It sets up all the data structures and system workqueues and allows early
+ * boot code to create workqueues and queue/cancel work items. Actual work item
+ * execution starts only after kthreads can be created and scheduled right
+ * before early initcalls.
*/
-int __init workqueue_init_early(void)
+void __init workqueue_init_early(void)
{
+ struct wq_pod_type *pt = &wq_pod_types[WQ_AFFN_SYSTEM];
int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL };
- int hk_flags = HK_FLAG_DOMAIN | HK_FLAG_WQ;
+ void (*irq_work_fns[2])(struct irq_work *) = { bh_pool_kick_normal,
+ bh_pool_kick_highpri };
int i, cpu;
- WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));
+ BUILD_BUG_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));
BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL));
- cpumask_copy(wq_unbound_cpumask, housekeeping_cpumask(hk_flags));
+ BUG_ON(!alloc_cpumask_var(&wq_requested_unbound_cpumask, GFP_KERNEL));
+ BUG_ON(!zalloc_cpumask_var(&wq_isolated_cpumask, GFP_KERNEL));
+
+ cpumask_copy(wq_unbound_cpumask, cpu_possible_mask);
+ restrict_unbound_cpumask("HK_TYPE_WQ", housekeeping_cpumask(HK_TYPE_WQ));
+ restrict_unbound_cpumask("HK_TYPE_DOMAIN", housekeeping_cpumask(HK_TYPE_DOMAIN));
+ if (!cpumask_empty(&wq_cmdline_cpumask))
+ restrict_unbound_cpumask("workqueue.unbound_cpus", &wq_cmdline_cpumask);
+
+ cpumask_copy(wq_requested_unbound_cpumask, wq_unbound_cpumask);
pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);
- /* initialize CPU pools */
+ wq_update_pod_attrs_buf = alloc_workqueue_attrs();
+ BUG_ON(!wq_update_pod_attrs_buf);
+
+ /*
+ * If nohz_full is enabled, set power efficient workqueue as unbound.
+ * This allows workqueue items to be moved to HK CPUs.
+ */
+ if (housekeeping_enabled(HK_TYPE_TICK))
+ wq_power_efficient = true;
+
+ /* initialize WQ_AFFN_SYSTEM pods */
+ pt->pod_cpus = kcalloc(1, sizeof(pt->pod_cpus[0]), GFP_KERNEL);
+ pt->pod_node = kcalloc(1, sizeof(pt->pod_node[0]), GFP_KERNEL);
+ pt->cpu_pod = kcalloc(nr_cpu_ids, sizeof(pt->cpu_pod[0]), GFP_KERNEL);
+ BUG_ON(!pt->pod_cpus || !pt->pod_node || !pt->cpu_pod);
+
+ BUG_ON(!zalloc_cpumask_var_node(&pt->pod_cpus[0], GFP_KERNEL, NUMA_NO_NODE));
+
+ pt->nr_pods = 1;
+ cpumask_copy(pt->pod_cpus[0], cpu_possible_mask);
+ pt->pod_node[0] = NUMA_NO_NODE;
+ pt->cpu_pod[0] = 0;
+
+ /* initialize BH and CPU pools */
for_each_possible_cpu(cpu) {
struct worker_pool *pool;
i = 0;
- for_each_cpu_worker_pool(pool, cpu) {
- BUG_ON(init_worker_pool(pool));
- pool->cpu = cpu;
- cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu));
- pool->attrs->nice = std_nice[i++];
- pool->node = cpu_to_node(cpu);
-
- /* alloc pool ID */
- mutex_lock(&wq_pool_mutex);
- BUG_ON(worker_pool_assign_id(pool));
- mutex_unlock(&wq_pool_mutex);
+ for_each_bh_worker_pool(pool, cpu) {
+ init_cpu_worker_pool(pool, cpu, std_nice[i]);
+ pool->flags |= POOL_BH;
+ init_irq_work(bh_pool_irq_work(pool), irq_work_fns[i]);
+ i++;
}
+
+ i = 0;
+ for_each_cpu_worker_pool(pool, cpu)
+ init_cpu_worker_pool(pool, cpu, std_nice[i++]);
}
/* create default unbound and ordered wq attrs */
for (i = 0; i < NR_STD_WORKER_POOLS; i++) {
struct workqueue_attrs *attrs;
- BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL)));
+ BUG_ON(!(attrs = alloc_workqueue_attrs()));
attrs->nice = std_nice[i];
unbound_std_wq_attrs[i] = attrs;
/*
* An ordered wq should have only one pwq as ordering is
* guaranteed by max_active which is enforced by pwqs.
- * Turn off NUMA so that dfl_pwq is used for all nodes.
*/
- BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL)));
+ BUG_ON(!(attrs = alloc_workqueue_attrs()));
attrs->nice = std_nice[i];
- attrs->no_numa = true;
+ attrs->ordered = true;
ordered_wq_attrs[i] = attrs;
}
system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0);
system_long_wq = alloc_workqueue("events_long", 0, 0);
system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
- WQ_UNBOUND_MAX_ACTIVE);
+ WQ_MAX_ACTIVE);
system_freezable_wq = alloc_workqueue("events_freezable",
WQ_FREEZABLE, 0);
system_power_efficient_wq = alloc_workqueue("events_power_efficient",
WQ_POWER_EFFICIENT, 0);
- system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient",
+ system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_pwr_efficient",
WQ_FREEZABLE | WQ_POWER_EFFICIENT,
0);
+ system_bh_wq = alloc_workqueue("events_bh", WQ_BH, 0);
+ system_bh_highpri_wq = alloc_workqueue("events_bh_highpri",
+ WQ_BH | WQ_HIGHPRI, 0);
BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq ||
!system_unbound_wq || !system_freezable_wq ||
!system_power_efficient_wq ||
- !system_freezable_power_efficient_wq);
+ !system_freezable_power_efficient_wq ||
+ !system_bh_wq || !system_bh_highpri_wq);
+}
- return 0;
+static void __init wq_cpu_intensive_thresh_init(void)
+{
+ unsigned long thresh;
+ unsigned long bogo;
+
+ pwq_release_worker = kthread_create_worker(0, "pool_workqueue_release");
+ BUG_ON(IS_ERR(pwq_release_worker));
+
+ /* if the user set it to a specific value, keep it */
+ if (wq_cpu_intensive_thresh_us != ULONG_MAX)
+ return;
+
+ /*
+ * The default of 10ms is derived from the fact that most modern (as of
+ * 2023) processors can do a lot in 10ms and that it's just below what
+ * most consider human-perceivable. However, the kernel also runs on a
+ * lot slower CPUs including microcontrollers where the threshold is way
+ * too low.
+ *
+ * Let's scale up the threshold upto 1 second if BogoMips is below 4000.
+ * This is by no means accurate but it doesn't have to be. The mechanism
+ * is still useful even when the threshold is fully scaled up. Also, as
+ * the reports would usually be applicable to everyone, some machines
+ * operating on longer thresholds won't significantly diminish their
+ * usefulness.
+ */
+ thresh = 10 * USEC_PER_MSEC;
+
+ /* see init/calibrate.c for lpj -> BogoMIPS calculation */
+ bogo = max_t(unsigned long, loops_per_jiffy / 500000 * HZ, 1);
+ if (bogo < 4000)
+ thresh = min_t(unsigned long, thresh * 4000 / bogo, USEC_PER_SEC);
+
+ pr_debug("wq_cpu_intensive_thresh: lpj=%lu BogoMIPS=%lu thresh_us=%lu\n",
+ loops_per_jiffy, bogo, thresh);
+
+ wq_cpu_intensive_thresh_us = thresh;
}
/**
* workqueue_init - bring workqueue subsystem fully online
*
- * This is the latter half of two-staged workqueue subsystem initialization
- * and invoked as soon as kthreads can be created and scheduled.
- * Workqueues have been created and work items queued on them, but there
- * are no kworkers executing the work items yet. Populate the worker pools
- * with the initial workers and enable future kworker creations.
+ * This is the second step of three-staged workqueue subsystem initialization
+ * and invoked as soon as kthreads can be created and scheduled. Workqueues have
+ * been created and work items queued on them, but there are no kworkers
+ * executing the work items yet. Populate the worker pools with the initial
+ * workers and enable future kworker creations.
*/
-int __init workqueue_init(void)
+void __init workqueue_init(void)
{
struct workqueue_struct *wq;
struct worker_pool *pool;
int cpu, bkt;
- /*
- * It'd be simpler to initialize NUMA in workqueue_init_early() but
- * CPU to node mapping may not be available that early on some
- * archs such as power and arm64. As per-cpu pools created
- * previously could be missing node hint and unbound pools NUMA
- * affinity, fix them up.
- *
- * Also, while iterating workqueues, create rescuers if requested.
- */
- wq_numa_init();
+ wq_cpu_intensive_thresh_init();
mutex_lock(&wq_pool_mutex);
+ /*
+ * Per-cpu pools created earlier could be missing node hint. Fix them
+ * up. Also, create a rescuer for workqueues that requested it.
+ */
for_each_possible_cpu(cpu) {
- for_each_cpu_worker_pool(pool, cpu) {
+ for_each_bh_worker_pool(pool, cpu)
+ pool->node = cpu_to_node(cpu);
+ for_each_cpu_worker_pool(pool, cpu)
pool->node = cpu_to_node(cpu);
- }
}
list_for_each_entry(wq, &workqueues, list) {
- wq_update_unbound_numa(wq, smp_processor_id(), true);
WARN(init_rescuer(wq),
"workqueue: failed to create early rescuer for %s",
wq->name);
mutex_unlock(&wq_pool_mutex);
- /* create the initial workers */
+ /*
+ * Create the initial workers. A BH pool has one pseudo worker that
+ * represents the shared BH execution context and thus doesn't get
+ * affected by hotplug events. Create the BH pseudo workers for all
+ * possible CPUs here.
+ */
+ for_each_possible_cpu(cpu)
+ for_each_bh_worker_pool(pool, cpu)
+ BUG_ON(!create_worker(pool));
+
for_each_online_cpu(cpu) {
for_each_cpu_worker_pool(pool, cpu) {
pool->flags &= ~POOL_DISASSOCIATED;
wq_online = true;
wq_watchdog_init();
+}
- return 0;
+/*
+ * Initialize @pt by first initializing @pt->cpu_pod[] with pod IDs according to
+ * @cpu_shares_pod(). Each subset of CPUs that share a pod is assigned a unique
+ * and consecutive pod ID. The rest of @pt is initialized accordingly.
+ */
+static void __init init_pod_type(struct wq_pod_type *pt,
+ bool (*cpus_share_pod)(int, int))
+{
+ int cur, pre, cpu, pod;
+
+ pt->nr_pods = 0;
+
+ /* init @pt->cpu_pod[] according to @cpus_share_pod() */
+ pt->cpu_pod = kcalloc(nr_cpu_ids, sizeof(pt->cpu_pod[0]), GFP_KERNEL);
+ BUG_ON(!pt->cpu_pod);
+
+ for_each_possible_cpu(cur) {
+ for_each_possible_cpu(pre) {
+ if (pre >= cur) {
+ pt->cpu_pod[cur] = pt->nr_pods++;
+ break;
+ }
+ if (cpus_share_pod(cur, pre)) {
+ pt->cpu_pod[cur] = pt->cpu_pod[pre];
+ break;
+ }
+ }
+ }
+
+ /* init the rest to match @pt->cpu_pod[] */
+ pt->pod_cpus = kcalloc(pt->nr_pods, sizeof(pt->pod_cpus[0]), GFP_KERNEL);
+ pt->pod_node = kcalloc(pt->nr_pods, sizeof(pt->pod_node[0]), GFP_KERNEL);
+ BUG_ON(!pt->pod_cpus || !pt->pod_node);
+
+ for (pod = 0; pod < pt->nr_pods; pod++)
+ BUG_ON(!zalloc_cpumask_var(&pt->pod_cpus[pod], GFP_KERNEL));
+
+ for_each_possible_cpu(cpu) {
+ cpumask_set_cpu(cpu, pt->pod_cpus[pt->cpu_pod[cpu]]);
+ pt->pod_node[pt->cpu_pod[cpu]] = cpu_to_node(cpu);
+ }
+}
+
+static bool __init cpus_dont_share(int cpu0, int cpu1)
+{
+ return false;
+}
+
+static bool __init cpus_share_smt(int cpu0, int cpu1)
+{
+#ifdef CONFIG_SCHED_SMT
+ return cpumask_test_cpu(cpu0, cpu_smt_mask(cpu1));
+#else
+ return false;
+#endif
+}
+
+static bool __init cpus_share_numa(int cpu0, int cpu1)
+{
+ return cpu_to_node(cpu0) == cpu_to_node(cpu1);
+}
+
+/**
+ * workqueue_init_topology - initialize CPU pods for unbound workqueues
+ *
+ * This is the third step of three-staged workqueue subsystem initialization and
+ * invoked after SMP and topology information are fully initialized. It
+ * initializes the unbound CPU pods accordingly.
+ */
+void __init workqueue_init_topology(void)
+{
+ struct workqueue_struct *wq;
+ int cpu;
+
+ init_pod_type(&wq_pod_types[WQ_AFFN_CPU], cpus_dont_share);
+ init_pod_type(&wq_pod_types[WQ_AFFN_SMT], cpus_share_smt);
+ init_pod_type(&wq_pod_types[WQ_AFFN_CACHE], cpus_share_cache);
+ init_pod_type(&wq_pod_types[WQ_AFFN_NUMA], cpus_share_numa);
+
+ wq_topo_initialized = true;
+
+ mutex_lock(&wq_pool_mutex);
+
+ /*
+ * Workqueues allocated earlier would have all CPUs sharing the default
+ * worker pool. Explicitly call wq_update_pod() on all workqueue and CPU
+ * combinations to apply per-pod sharing.
+ */
+ list_for_each_entry(wq, &workqueues, list) {
+ for_each_online_cpu(cpu)
+ wq_update_pod(wq, cpu, cpu, true);
+ if (wq->flags & WQ_UNBOUND) {
+ mutex_lock(&wq->mutex);
+ wq_update_node_max_active(wq, -1);
+ mutex_unlock(&wq->mutex);
+ }
+ }
+
+ mutex_unlock(&wq_pool_mutex);
+}
+
+void __warn_flushing_systemwide_wq(void)
+{
+ pr_warn("WARNING: Flushing system-wide workqueues will be prohibited in near future.\n");
+ dump_stack();
+}
+EXPORT_SYMBOL(__warn_flushing_systemwide_wq);
+
+static int __init workqueue_unbound_cpus_setup(char *str)
+{
+ if (cpulist_parse(str, &wq_cmdline_cpumask) < 0) {
+ cpumask_clear(&wq_cmdline_cpumask);
+ pr_warn("workqueue.unbound_cpus: incorrect CPU range, using default\n");
+ }
+
+ return 1;
}
+__setup("workqueue.unbound_cpus=", workqueue_unbound_cpus_setup);
git.samba.org / sfrench / cifs-2.6.git / blobdiff