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: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index 93c5d5e..7473ee3 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -60,14 +60,15 @@
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 @@
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 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);