Subject: + lib-percpu_counterc-disable-local-irq-when-updating-percpu-couter.patch added to -mm tree
To: tom.leiming@xxxxxxxxx,akpm@xxxxxxxxxxxxxxxxxxxx,axboe@xxxxxxxxx,fan.du@xxxxxxxxxxxxx,paul.gortmaker@xxxxxxxxxxxxx,shli@xxxxxxxxxxxx,stable@xxxxxxxxxxxxxxx,tj@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 07 Jan 2014 14:29:01 -0800
The patch titled
Subject: lib/percpu_counter.c: disable local irq when updating percpu couter
has been added to the -mm tree. Its filename is
lib-percpu_counterc-disable-local-irq-when-updating-percpu-couter.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/lib-percpu_counterc-disable-local-irq-when-updating-percpu-couter.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/lib-percpu_counterc-disable-local-irq-when-updating-percpu-couter.patch
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------------------------------------------------------
From: Ming Lei <tom.leiming@xxxxxxxxx>
Subject: lib/percpu_counter.c: disable local irq when updating percpu couter
__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.
Signed-off-by: Ming Lei <tom.leiming@xxxxxxxxx>
Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Shaohua Li <shli@xxxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Fan Du <fan.du@xxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/percpu_counter.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff -puN lib/percpu_counter.c~lib-percpu_counterc-disable-local-irq-when-updating-percpu-couter lib/percpu_counter.c
--- a/lib/percpu_counter.c~lib-percpu_counterc-disable-local-irq-when-updating-percpu-couter
+++ a/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);
_
Patches currently in -mm which might be from tom.leiming@xxxxxxxxx are
lib-percpu_counterc-disable-local-irq-when-updating-percpu-couter.patch
linux-next.patch
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