__percpu_counter_add() may be called in softirq/hardirq handler
(such as, blk_mq_queue_exit() is typically called in hardirq/softirq
handler), so we need to disable local irq when updating the percpu
counter, otherwise counts may be lost.
The patch fixes problem that 'rmmod null_blk' may hang in blk_cleanup_queue()
because of miscounting of request_queue->mq_usage_counter.
Cc: Paul Gortmaker <paul.gortma...@windriver.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Shaohua Li <s...@fusionio.com>
Cc: Jens Axboe <ax...@kernel.dk>
Cc: Fan Du <fan...@windriver.com>
Signed-off-by: Ming Lei <tom.leim...@gmail.com>
---
lib/percpu_counter.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index 7473ee3..2b87bc1 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -75,19 +75,19 @@ EXPORT_SYMBOL(percpu_counter_set);
void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)
{
s64 count;
+ unsigned long flags;
- preempt_disable();
+ raw_local_irq_save(flags);
count = __this_cpu_read(*fbc->counters) + amount;
if (count >= batch || count <= -batch) {
- unsigned long flags;
- raw_spin_lock_irqsave(&fbc->lock, flags);
+ raw_spin_lock(&fbc->lock);
fbc->count += count;
- raw_spin_unlock_irqrestore(&fbc->lock, flags);
+ raw_spin_unlock(&fbc->lock);
__this_cpu_write(*fbc->counters, 0);
} else {
__this_cpu_write(*fbc->counters, count);
}
- preempt_enable();
+ raw_local_irq_restore(flags);
}
EXPORT_SYMBOL(__percpu_counter_add);
--
1.7.9.5
--
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