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Add irq protection in the percpu-counters cpu-hotplug-callback path

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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>
This commit is contained in:
Gautham R Shenoy 2007-10-18 23:40:47 -07:00 committed by Linus Torvalds
parent 73e753a50d
commit d2b20b1154
1 changed files with 3 additions and 2 deletions
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5
lib/percpu_counter.c
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@ -124,12 +124,13 @@ static int __cpuinit percpu_counter_hotcpu_callback(struct notifier_block *nb,
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;