watchdog/hardlockup: detect hard lockups using secondary (buddy) CPUs

[sfrench/cifs-2.6.git] / kernel / watchdog.c

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index e67125f64719339479eecdd665ef888fb66b398d..10947c83507987ddd1ab06c179c148125c520172 100644 (file)
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -85,7 +85,7 @@ __setup("nmi_watchdog=", hardlockup_panic_setup);
 
 #endif /* CONFIG_HARDLOCKUP_DETECTOR */
 
-#if defined(CONFIG_HARDLOCKUP_DETECTOR_PERF)
+#if defined(CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER)
 
 static DEFINE_PER_CPU(atomic_t, hrtimer_interrupts);
 static DEFINE_PER_CPU(int, hrtimer_interrupts_saved);
@@ -106,6 +106,14 @@ notrace void arch_touch_nmi_watchdog(void)
 }
 EXPORT_SYMBOL(arch_touch_nmi_watchdog);
 
+void watchdog_hardlockup_touch_cpu(unsigned int cpu)
+{
+       per_cpu(watchdog_hardlockup_touched, cpu) = true;
+
+       /* Match with smp_rmb() in watchdog_hardlockup_check() */
+       smp_wmb();
+}
+
 static bool is_hardlockup(unsigned int cpu)
 {
        int hrint = atomic_read(&per_cpu(hrtimer_interrupts, cpu));
@@ -123,13 +131,16 @@ static bool is_hardlockup(unsigned int cpu)
        return false;
 }
 
-static void watchdog_hardlockup_kick(void)
+static unsigned long watchdog_hardlockup_kick(void)
 {
-       atomic_inc(raw_cpu_ptr(&hrtimer_interrupts));
+       return atomic_inc_return(raw_cpu_ptr(&hrtimer_interrupts));
 }
 
 void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs)
 {
+       /* Match with smp_wmb() in watchdog_hardlockup_touch_cpu() */
+       smp_rmb();
+
        if (per_cpu(watchdog_hardlockup_touched, cpu)) {
                per_cpu(watchdog_hardlockup_touched, cpu) = false;
                return;
@@ -180,11 +191,11 @@ void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs)
        }
 }
 
-#else /* CONFIG_HARDLOCKUP_DETECTOR_PERF */
+#else /* CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER */
 
-static inline void watchdog_hardlockup_kick(void) { }
+static inline unsigned long watchdog_hardlockup_kick(void) { return 0; }
 
-#endif /* !CONFIG_HARDLOCKUP_DETECTOR_PERF */
+#endif /* !CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER */
 
 /*
  * These functions can be overridden based on the configured hardlockdup detector.
@@ -443,11 +454,15 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
        struct pt_regs *regs = get_irq_regs();
        int duration;
        int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace;
+       unsigned long hrtimer_interrupts;
 
        if (!watchdog_enabled)
                return HRTIMER_NORESTART;
 
-       watchdog_hardlockup_kick();
+       hrtimer_interrupts = watchdog_hardlockup_kick();
+
+       /* test for hardlockups */
+       watchdog_buddy_check_hardlockup(hrtimer_interrupts);
 
        /* kick the softlockup detector */
        if (completion_done(this_cpu_ptr(&softlockup_completion))) {