Re: [PATCH v2 5/6] blk-mq: fix freeze queue race

[Tejun Heo]

On Thu, Jul 02, 2015 at 11:29:56PM +0900, Akinobu Mita wrote:
> There are several race conditions while freezing queue.
...
> Also, percpu_ref_reinit() and percpu_ref_kill() must not be executed
> at the same time.  Because both functions could call
> __percpu_ref_switch_to_percpu() which adds the bias value and
> initialize percpu counter.
> 
> Fix those races by serializing with per-queue mutex.
> 
> Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
> Cc: Jens Axboe <axboe@xxxxxxxxx>
> Cc: Ming Lei <tom.leiming@xxxxxxxxx>

Yeap, all of the kill/reinit/switch mode functions assume caller side
synchronization.

Acked-by: Tejun Heo <tj@xxxxxxxxxx>

Thanks.

-- 
tejun
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