Hello, Ming.

On Tue, Apr 10, 2018 at 11:25:54PM +0800, Ming Lei wrote:
> +   if (time_after_eq(jiffies, deadline) &&
> +       blk_mq_change_rq_state(rq, MQ_RQ_IN_FLIGHT, MQ_RQ_COMPLETE)) {
> +       blk_mq_rq_timed_out(rq, reserved);
> 
> Normal completion still can happen between blk_mq_change_rq_state()
> and blk_mq_rq_timed_out().
> 
> In tj's approach, there is synchronize_rcu() between writing aborted_gstate
> and blk_mq_rq_timed_out, it is easier for normal completion to happen during
> the big window.

I don't think plugging this hole is all that difficult, but this
shouldn't lead to any critical failures.  If so, that'd be a driver
bug.

Thanks.

-- 
tejun

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