return __get_task_for_clock(clock, false, false) ? 0 : -EINVAL;
}
+static inline enum pid_type cpu_timer_pid_type(struct k_itimer *timer)
+{
+ return CPUCLOCK_PERTHREAD(timer->it_clock) ? PIDTYPE_PID : PIDTYPE_TGID;
+}
+
+static inline struct task_struct *cpu_timer_task_rcu(struct k_itimer *timer)
+{
+ return pid_task(timer->it.cpu.pid, cpu_timer_pid_type(timer));
+}
+
/*
* Update expiry time from increment, and increase overrun count,
* given the current clock sample.
/*
* Sample a process (thread group) clock for the given task clkid. If the
* group's cputime accounting is already enabled, read the atomic
- * store. Otherwise a full update is required. Task's sighand lock must be
- * held to protect the task traversal on a full update. clkid is already
- * validated.
+ * store. Otherwise a full update is required. clkid is already validated.
*/
static u64 cpu_clock_sample_group(const clockid_t clkid, struct task_struct *p,
bool start)
new_timer->kclock = &clock_posix_cpu;
timerqueue_init(&new_timer->it.cpu.node);
- new_timer->it.cpu.task = p;
+ new_timer->it.cpu.pid = get_task_pid(p, cpu_timer_pid_type(new_timer));
+ /*
+ * get_task_for_clock() took a reference on @p. Drop it as the timer
+ * holds a reference on the pid of @p.
+ */
+ put_task_struct(p);
return 0;
}
static int posix_cpu_timer_del(struct k_itimer *timer)
{
struct cpu_timer *ctmr = &timer->it.cpu;
- struct task_struct *p = ctmr->task;
struct sighand_struct *sighand;
+ struct task_struct *p;
unsigned long flags;
int ret = 0;
- if (WARN_ON_ONCE(!p))
- return -EINVAL;
+ rcu_read_lock();
+ p = cpu_timer_task_rcu(timer);
+ if (!p)
+ goto out;
/*
* Protect against sighand release/switch in exit/exec and process/
unlock_task_sighand(p, &flags);
}
+out:
+ rcu_read_unlock();
if (!ret)
- put_task_struct(p);
+ put_pid(ctmr->pid);
return ret;
}
* Insert the timer on the appropriate list before any timers that
* expire later. This must be called with the sighand lock held.
*/
-static void arm_timer(struct k_itimer *timer)
+static void arm_timer(struct k_itimer *timer, struct task_struct *p)
{
int clkidx = CPUCLOCK_WHICH(timer->it_clock);
struct cpu_timer *ctmr = &timer->it.cpu;
u64 newexp = cpu_timer_getexpires(ctmr);
- struct task_struct *p = ctmr->task;
struct posix_cputimer_base *base;
if (CPUCLOCK_PERTHREAD(timer->it_clock))
clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock);
u64 old_expires, new_expires, old_incr, val;
struct cpu_timer *ctmr = &timer->it.cpu;
- struct task_struct *p = ctmr->task;
struct sighand_struct *sighand;
+ struct task_struct *p;
unsigned long flags;
int ret = 0;
- if (WARN_ON_ONCE(!p))
- return -EINVAL;
+ rcu_read_lock();
+ p = cpu_timer_task_rcu(timer);
+ if (!p) {
+ /*
+ * If p has just been reaped, we can no
+ * longer get any information about it at all.
+ */
+ rcu_read_unlock();
+ return -ESRCH;
+ }
/*
* Use the to_ktime conversion because that clamps the maximum
* If p has just been reaped, we can no
* longer get any information about it at all.
*/
- if (unlikely(sighand == NULL))
+ if (unlikely(sighand == NULL)) {
+ rcu_read_unlock();
return -ESRCH;
+ }
/*
* Disarm any old timer after extracting its expiry time.
*/
cpu_timer_setexpires(ctmr, new_expires);
if (new_expires != 0 && val < new_expires) {
- arm_timer(timer);
+ arm_timer(timer, p);
}
unlock_task_sighand(p, &flags);
ret = 0;
out:
+ rcu_read_unlock();
if (old)
old->it_interval = ns_to_timespec64(old_incr);
clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock);
struct cpu_timer *ctmr = &timer->it.cpu;
u64 now, expires = cpu_timer_getexpires(ctmr);
- struct task_struct *p = ctmr->task;
+ struct task_struct *p;
- if (WARN_ON_ONCE(!p))
- return;
+ rcu_read_lock();
+ p = cpu_timer_task_rcu(timer);
+ if (!p)
+ goto out;
/*
* Easy part: convert the reload time.
itp->it_interval = ktime_to_timespec64(timer->it_interval);
if (!expires)
- return;
+ goto out;
/*
* Sample the clock to take the difference with the expiry time.
*/
- if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
+ if (CPUCLOCK_PERTHREAD(timer->it_clock))
now = cpu_clock_sample(clkid, p);
- } else {
- struct sighand_struct *sighand;
- unsigned long flags;
-
- /*
- * Protect against sighand release/switch in exit/exec and
- * also make timer sampling safe if it ends up calling
- * thread_group_cputime().
- */
- sighand = lock_task_sighand(p, &flags);
- if (unlikely(sighand == NULL)) {
- /*
- * The process has been reaped.
- * We can't even collect a sample any more.
- * Disarm the timer, nothing else to do.
- */
- cpu_timer_setexpires(ctmr, 0);
- return;
- } else {
- now = cpu_clock_sample_group(clkid, p, false);
- unlock_task_sighand(p, &flags);
- }
- }
+ else
+ now = cpu_clock_sample_group(clkid, p, false);
if (now < expires) {
itp->it_value = ns_to_timespec64(expires - now);
itp->it_value.tv_nsec = 1;
itp->it_value.tv_sec = 0;
}
+out:
+ rcu_read_unlock();
}
#define MAX_COLLECTED 20
static void posix_cpu_timer_rearm(struct k_itimer *timer)
{
clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock);
- struct cpu_timer *ctmr = &timer->it.cpu;
- struct task_struct *p = ctmr->task;
+ struct task_struct *p;
struct sighand_struct *sighand;
unsigned long flags;
u64 now;
- if (WARN_ON_ONCE(!p))
- return;
+ rcu_read_lock();
+ p = cpu_timer_task_rcu(timer);
+ if (!p)
+ goto out;
/*
* Fetch the current sample and update the timer's expiry time.
*/
- if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
+ if (CPUCLOCK_PERTHREAD(timer->it_clock))
now = cpu_clock_sample(clkid, p);
- bump_cpu_timer(timer, now);
- if (unlikely(p->exit_state))
- return;
-
- /* Protect timer list r/w in arm_timer() */
- sighand = lock_task_sighand(p, &flags);
- if (!sighand)
- return;
- } else {
- /*
- * Protect arm_timer() and timer sampling in case of call to
- * thread_group_cputime().
- */
- sighand = lock_task_sighand(p, &flags);
- if (unlikely(sighand == NULL)) {
- /*
- * The process has been reaped.
- * We can't even collect a sample any more.
- */
- cpu_timer_setexpires(ctmr, 0);
- return;
- } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
- /* If the process is dying, no need to rearm */
- goto unlock;
- }
+ else
now = cpu_clock_sample_group(clkid, p, true);
- bump_cpu_timer(timer, now);
- /* Leave the sighand locked for the call below. */
- }
+
+ bump_cpu_timer(timer, now);
+
+ /* Protect timer list r/w in arm_timer() */
+ sighand = lock_task_sighand(p, &flags);
+ if (unlikely(sighand == NULL))
+ goto out;
/*
* Now re-arm for the new expiry time.
*/
- arm_timer(timer);
-unlock:
+ arm_timer(timer, p);
unlock_task_sighand(p, &flags);
+out:
+ rcu_read_unlock();
}
/**
git.samba.org / sfrench / cifs-2.6.git / blobdiff