[PATCH v6 17/46] clockevents: Use get/put_online_cpus_atomic() in clockevents_notify()
From: Srivatsa S. Bhat <hidden>
Date: 2013-02-18 12:42:52
Also in:
linux-arch, linux-arm-kernel, linux-pm, lkml, netdev
Subsystem:
high-resolution timers, timer wheel, clockevents, the rest · Maintainers:
Anna-Maria Behnsen, Frederic Weisbecker, Thomas Gleixner, Linus Torvalds
The cpu idle code invokes clockevents_notify() during idle state transitions and the cpu offline code invokes it during the CPU_DYING phase. There seems to be a race-condition between the two, where the clockevents_lock never gets released, ending in a lockup. This can be fixed by synchronizing clockevents_notify() with CPU offline, by wrapping its contents within get/put_online_cpus_atomic(). Signed-off-by: Srivatsa S. Bhat <redacted> --- kernel/time/clockevents.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 30b6de0..ca340fd 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c@@ -17,6 +17,7 @@ #include <linux/module.h> #include <linux/notifier.h> #include <linux/smp.h> +#include <linux/cpu.h> #include "tick-internal.h"
@@ -431,6 +432,7 @@ void clockevents_notify(unsigned long reason, void *arg) unsigned long flags; int cpu; + get_online_cpus_atomic(); raw_spin_lock_irqsave(&clockevents_lock, flags); clockevents_do_notify(reason, arg);
@@ -459,6 +461,7 @@ void clockevents_notify(unsigned long reason, void *arg) break; } raw_spin_unlock_irqrestore(&clockevents_lock, flags); + put_online_cpus_atomic(); } EXPORT_SYMBOL_GPL(clockevents_notify); #endif