watchdog/hardlockup: adopt softlockup logic avoiding double-dumps

[linux-2.6-microblaze.git] / kernel / watchdog.c

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index bf30a6f..b4fd2f1 100644 (file)
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -91,7 +91,7 @@ static DEFINE_PER_CPU(atomic_t, hrtimer_interrupts);
 static DEFINE_PER_CPU(int, hrtimer_interrupts_saved);
 static DEFINE_PER_CPU(bool, watchdog_hardlockup_warned);
 static DEFINE_PER_CPU(bool, watchdog_hardlockup_touched);
-static unsigned long watchdog_hardlockup_all_cpu_dumped;
+static unsigned long hard_lockup_nmi_warn;
 
 notrace void arch_touch_nmi_watchdog(void)
 {
@@ -156,6 +156,15 @@ void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs)
                if (per_cpu(watchdog_hardlockup_warned, cpu))
                        return;
 
+               /*
+                * Prevent multiple hard-lockup reports if one cpu is already
+                * engaged in dumping all cpu back traces.
+                */
+               if (sysctl_hardlockup_all_cpu_backtrace) {
+                       if (test_and_set_bit_lock(0, &hard_lockup_nmi_warn))
+                               return;
+               }
+
                pr_emerg("Watchdog detected hard LOCKUP on cpu %d\n", cpu);
                print_modules();
                print_irqtrace_events(current);
@@ -168,13 +177,10 @@ void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs)
                        trigger_single_cpu_backtrace(cpu);
                }
 
-               /*
-                * Perform multi-CPU dump only once to avoid multiple
-                * hardlockups generating interleaving traces
-                */
-               if (sysctl_hardlockup_all_cpu_backtrace &&
-                   !test_and_set_bit(0, &watchdog_hardlockup_all_cpu_dumped))
+               if (sysctl_hardlockup_all_cpu_backtrace) {
                        trigger_allbutcpu_cpu_backtrace(cpu);
+                       clear_bit_unlock(0, &hard_lockup_nmi_warn);
+               }
 
                if (hardlockup_panic)
                        nmi_panic(regs, "Hard LOCKUP");