From d2b20b11547cefc89d6c81937e81afaf3c62808b Mon Sep 17 00:00:00 2001 From: Gautham R Shenoy Date: Thu, 18 Oct 2007 23:40:47 -0700 Subject: [PATCH] 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 Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/percpu_counter.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c index 9659eabffc3..393a0e915c2 100644 --- a/lib/percpu_counter.c +++ b/lib/percpu_counter.c @@ -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; -- 2.41.1