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Commit 098faf58 authored by Shaohua Li's avatar Shaohua Li Committed by Jens Axboe
Browse files

percpu_counter: make APIs irq safe 



In my usage, sometimes the percpu APIs are called with irq locked,
sometimes not. lockdep complains there is potential deadlock. Let's
always use percpucounter lock in irq safe way. There should be no
performance penality, as all those are slow code path.

Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarShaohua Li <shli@fusionio.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 71fe07d0

lib/percpu_counter.c

+9 −6
Original line number Diff line number Diff line
@@ -60,14 +60,15 @@ static inline void debug_percpu_counter_deactivate(struct percpu_counter *fbc) 
void percpu_counter_set(struct percpu_counter *fbc, s64 amount)

{

	int cpu;

	unsigned long flags;



	raw_spin_lock(&fbc->lock);

	raw_spin_lock_irqsave(&fbc->lock, flags);

	for_each_possible_cpu(cpu) {

		s32 *pcount = per_cpu_ptr(fbc->counters, cpu);

		*pcount = 0;

	}

	fbc->count = amount;

	raw_spin_unlock(&fbc->lock);

	raw_spin_unlock_irqrestore(&fbc->lock, flags);

}

EXPORT_SYMBOL(percpu_counter_set);
@@ -78,9 +79,10 @@ void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch) 
	preempt_disable();

	count = __this_cpu_read(*fbc->counters) + amount;

	if (count >= batch || count <= -batch) {

		raw_spin_lock(&fbc->lock);

		unsigned long flags;

		raw_spin_lock_irqsave(&fbc->lock, flags);

		fbc->count += count;

		raw_spin_unlock(&fbc->lock);

		raw_spin_unlock_irqrestore(&fbc->lock, flags);

		__this_cpu_write(*fbc->counters, 0);

	} else {

		__this_cpu_write(*fbc->counters, count);
@@ -97,14 +99,15 @@ s64 __percpu_counter_sum(struct percpu_counter *fbc) 
{

	s64 ret;

	int cpu;

	unsigned long flags;



	raw_spin_lock(&fbc->lock);

	raw_spin_lock_irqsave(&fbc->lock, flags);

	ret = fbc->count;

	for_each_online_cpu(cpu) {

		s32 *pcount = per_cpu_ptr(fbc->counters, cpu);

		ret += *pcount;

	}

	raw_spin_unlock(&fbc->lock);

	raw_spin_unlock_irqrestore(&fbc->lock, flags);

	return ret;

}

EXPORT_SYMBOL(__percpu_counter_sum);