Re: [RFC PATCH 2/3] blk-mq: Fix timeout and state order

Ming Lei
2018-05-22T02:28:14Z

On Mon, May 21, 2018 at 05:11:30PM -0600, Keith Busch wrote:
> The block layer had been setting the state to in-flight prior to updating
> the timer. This is the wrong order since the timeout handler could observe
> the in-flight state with the older timeout, believing the request had
> expired when in fact it is just getting started.
>
> Signed-off-by: Keith Busch <keith.busch@intel.com>
> ---
> block/blk-mq.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 8b370ed75605..66e5c768803f 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -713,8 +713,8 @@ void blk_mq_start_request(struct request *rq)
> preempt_disable();
> write_seqcount_begin(&rq->gstate_seq);
>
> - blk_mq_rq_update_state(rq, MQ_RQ_IN_FLIGHT);
> blk_add_timer(rq);
> + blk_mq_rq_update_state(rq, MQ_RQ_IN_FLIGHT);
>
> write_seqcount_end(&rq->gstate_seq);
> preempt_enable();
> --
> 2.14.3
>

Looks fine,

Reviewed-by: Ming Lei <ming.lei@redhat.com>

Thanks,
Ming