On Thu, 2017-04-20 at 17:09 -0600, Jens Axboe wrote:
> From: Jens Axboe <[email protected]>
> Subject: [PATCH] blk-mq: add might_sleep check to blk_mq_get_driver_tag()
> 
> If the caller passes in wait=true, it has to be able to block
> for a driver tag. We just had a bug where flush insertion
> would block on tag allocation, while we had preempt disabled.
> Ensure that we catch cases like that earlier next time.
> 
> Signed-off-by: Jens Axboe <[email protected]>
> 
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 992f09772f8a..dd6e5dd62804 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -866,6 +866,8 @@ bool blk_mq_get_driver_tag(struct request *rq, struct 
> blk_mq_hw_ctx **hctx,
>               .flags = wait ? 0 : BLK_MQ_REQ_NOWAIT,
>       };
>  
> +     might_sleep_if(wait);
> +
>       if (rq->tag != -1)
>               goto done;
>  
> 

Thanks!

Reviewed-by: Bart Van Assche <[email protected]>

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