Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit d2b20b11 authored by Gautham R Shenoy's avatar Gautham R Shenoy Committed by Linus Torvalds
Browse files

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: default avatarGautham R Shenoy <ego@in.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 73e753a5

lib/percpu_counter.c

+3 −2
Original line number Diff line number Diff line
@@ -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;