Add irq protection in the percpu-counters cpu-hotplug-callback path
Some of the per-cpu counters and thus their locks are accessed from IRQ
contexts. This can cause a deadlock if it interrupts a cpu-offline thread
which is transferring a dead-cpu's counts to the global counter.
Add appropriate IRQ protection in the cpu-hotplug callback path.
Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index 9659eab..393a0e9 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -124,12 +124,13 @@
mutex_lock(&percpu_counters_lock);
list_for_each_entry(fbc, &percpu_counters, list) {
s32 *pcount;
+ unsigned long flags;
- spin_lock(&fbc->lock);
+ spin_lock_irqsave(&fbc->lock, flags);
pcount = per_cpu_ptr(fbc->counters, cpu);
fbc->count += *pcount;
*pcount = 0;
- spin_unlock(&fbc->lock);
+ spin_unlock_irqrestore(&fbc->lock, flags);
}
mutex_unlock(&percpu_counters_lock);
return NOTIFY_OK;