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 93c5d5ecff4eacf79d10acfacb67dc4b205828e3..7473ee3b4ee712b0759e264b79f350457888be1e 100644 (file)
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -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);