#define pr_fmt(fmt) "NMI watchdog: " fmt
#include <linux/nmi.h>
+#include <linux/atomic.h>
#include <linux/module.h>
#include <linux/sched/debug.h>
static DEFINE_PER_CPU(bool, hard_watchdog_warn);
static DEFINE_PER_CPU(bool, watchdog_nmi_touch);
static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
+static DEFINE_PER_CPU(struct perf_event *, dead_event);
+static struct cpumask dead_events_mask;
static unsigned long hardlockup_allcpu_dumped;
+static atomic_t watchdog_cpus = ATOMIC_INIT(0);
void arch_touch_nmi_watchdog(void)
{
/* Callback function for perf event subsystem */
static void watchdog_overflow_callback(struct perf_event *event,
- struct perf_sample_data *data,
- struct pt_regs *regs)
+ struct perf_sample_data *data,
+ struct pt_regs *regs)
{
/* Ensure the watchdog never gets throttled */
event->hw.interrupts = 0;
- if (atomic_read(&watchdog_park_in_progress) != 0)
- return;
-
if (__this_cpu_read(watchdog_nmi_touch) == true) {
__this_cpu_write(watchdog_nmi_touch, false);
return;
return;
}
-/*
- * People like the simple clean cpu node info on boot.
- * Reduce the watchdog noise by only printing messages
- * that are different from what cpu0 displayed.
- */
-static unsigned long firstcpu_err;
-static atomic_t watchdog_cpus;
-
-int watchdog_nmi_enable(unsigned int cpu)
+static int hardlockup_detector_event_create(void)
{
+ unsigned int cpu = smp_processor_id();
struct perf_event_attr *wd_attr;
- struct perf_event *event = per_cpu(watchdog_ev, cpu);
- int firstcpu = 0;
-
- /* nothing to do if the hard lockup detector is disabled */
- if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))
- goto out;
-
- /* is it already setup and enabled? */
- if (event && event->state > PERF_EVENT_STATE_OFF)
- goto out;
-
- /* it is setup but not enabled */
- if (event != NULL)
- goto out_enable;
-
- if (atomic_inc_return(&watchdog_cpus) == 1)
- firstcpu = 1;
+ struct perf_event *evt;
wd_attr = &wd_hw_attr;
wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);
/* Try to register using hardware perf events */
- event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL);
+ evt = perf_event_create_kernel_counter(wd_attr, cpu, NULL,
+ watchdog_overflow_callback, NULL);
+ if (IS_ERR(evt)) {
+ pr_info("Perf event create on CPU %d failed with %ld\n", cpu,
+ PTR_ERR(evt));
+ return PTR_ERR(evt);
+ }
+ this_cpu_write(watchdog_ev, evt);
+ return 0;
+}
- /* save the first cpu's error for future comparision */
- if (firstcpu && IS_ERR(event))
- firstcpu_err = PTR_ERR(event);
+/**
+ * hardlockup_detector_perf_enable - Enable the local event
+ */
+void hardlockup_detector_perf_enable(void)
+{
+ if (hardlockup_detector_event_create())
+ return;
- if (!IS_ERR(event)) {
- /* only print for the first cpu initialized */
- if (firstcpu || firstcpu_err)
- pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n");
- goto out_save;
- }
+ /* use original value for check */
+ if (!atomic_fetch_inc(&watchdog_cpus))
+ pr_info("Enabled. Permanently consumes one hw-PMU counter.\n");
- /*
- * Disable the hard lockup detector if _any_ CPU fails to set up
- * set up the hardware perf event. The watchdog() function checks
- * the NMI_WATCHDOG_ENABLED bit periodically.
- *
- * The barriers are for syncing up watchdog_enabled across all the
- * cpus, as clear_bit() does not use barriers.
- */
- smp_mb__before_atomic();
- clear_bit(NMI_WATCHDOG_ENABLED_BIT, &watchdog_enabled);
- smp_mb__after_atomic();
-
- /* skip displaying the same error again */
- if (!firstcpu && (PTR_ERR(event) == firstcpu_err))
- return PTR_ERR(event);
-
- /* vary the KERN level based on the returned errno */
- if (PTR_ERR(event) == -EOPNOTSUPP)
- pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu);
- else if (PTR_ERR(event) == -ENOENT)
- pr_warn("disabled (cpu%i): hardware events not enabled\n",
- cpu);
- else
- pr_err("disabled (cpu%i): unable to create perf event: %ld\n",
- cpu, PTR_ERR(event));
-
- pr_info("Shutting down hard lockup detector on all cpus\n");
-
- return PTR_ERR(event);
-
- /* success path */
-out_save:
- per_cpu(watchdog_ev, cpu) = event;
-out_enable:
- perf_event_enable(per_cpu(watchdog_ev, cpu));
-out:
- return 0;
+ perf_event_enable(this_cpu_read(watchdog_ev));
}
-void watchdog_nmi_disable(unsigned int cpu)
+/**
+ * hardlockup_detector_perf_disable - Disable the local event
+ */
+void hardlockup_detector_perf_disable(void)
{
- struct perf_event *event = per_cpu(watchdog_ev, cpu);
+ struct perf_event *event = this_cpu_read(watchdog_ev);
if (event) {
perf_event_disable(event);
- per_cpu(watchdog_ev, cpu) = NULL;
+ this_cpu_write(watchdog_ev, NULL);
+ this_cpu_write(dead_event, event);
+ cpumask_set_cpu(smp_processor_id(), &dead_events_mask);
+ atomic_dec(&watchdog_cpus);
+ }
+}
+
+/**
+ * hardlockup_detector_perf_cleanup - Cleanup disabled events and destroy them
+ *
+ * Called from lockup_detector_cleanup(). Serialized by the caller.
+ */
+void hardlockup_detector_perf_cleanup(void)
+{
+ int cpu;
+
+ for_each_cpu(cpu, &dead_events_mask) {
+ struct perf_event *event = per_cpu(dead_event, cpu);
- /* should be in cleanup, but blocks oprofile */
- perf_event_release_kernel(event);
+ /*
+ * Required because for_each_cpu() reports unconditionally
+ * CPU0 as set on UP kernels. Sigh.
+ */
+ if (event)
+ perf_event_release_kernel(event);
+ per_cpu(dead_event, cpu) = NULL;
+ }
+ cpumask_clear(&dead_events_mask);
+}
+
+/**
+ * hardlockup_detector_perf_stop - Globally stop watchdog events
+ *
+ * Special interface for x86 to handle the perf HT bug.
+ */
+void __init hardlockup_detector_perf_stop(void)
+{
+ int cpu;
+
+ lockdep_assert_cpus_held();
+
+ for_each_online_cpu(cpu) {
+ struct perf_event *event = per_cpu(watchdog_ev, cpu);
+
+ if (event)
+ perf_event_disable(event);
+ }
+}
+
+/**
+ * hardlockup_detector_perf_restart - Globally restart watchdog events
+ *
+ * Special interface for x86 to handle the perf HT bug.
+ */
+void __init hardlockup_detector_perf_restart(void)
+{
+ int cpu;
+
+ lockdep_assert_cpus_held();
+
+ if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))
+ return;
+
+ for_each_online_cpu(cpu) {
+ struct perf_event *event = per_cpu(watchdog_ev, cpu);
+
+ if (event)
+ perf_event_enable(event);
+ }
+}
+
+/**
+ * hardlockup_detector_perf_init - Probe whether NMI event is available at all
+ */
+int __init hardlockup_detector_perf_init(void)
+{
+ int ret = hardlockup_detector_event_create();
- /* watchdog_nmi_enable() expects this to be zero initially. */
- if (atomic_dec_and_test(&watchdog_cpus))
- firstcpu_err = 0;
+ if (ret) {
+ pr_info("Perf NMI watchdog permanently disabled\n");
+ } else {
+ perf_event_release_kernel(this_cpu_read(watchdog_ev));
+ this_cpu_write(watchdog_ev, NULL);
}
+ return ret;
}
git.samba.org / sfrench / cifs-2.6.git / blobdiff