Re: [PATCH] scsi: core: only re-run queue in scsi_end_request() if device queue is busy

[Bart Van Assche <bvanassche@xxxxxxx>]

On 2019-11-17 00:08, Ming Lei wrote:
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index 379533ce8661..212903d5f43c 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -612,7 +612,7 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
>  	if (scsi_target(sdev)->single_lun ||
>  	    !list_empty(&sdev->host->starved_list))
>  		kblockd_schedule_work(&sdev->requeue_work);
> -	else
> +	else if (READ_ONCE(sdev->restart))
>  		blk_mq_run_hw_queues(q, true);
>  

Rerunning the hardware queues is not only necessary after
scsi_dev_queue_ready() returns false but also after .queuecommand()
returns SCSI_MLQUEUE_*_BUSY. Can this patch cause queue stalls if
.queuecommand() returns SCSI_MLQUEUE_*_BUSY?

Thanks,

Bart.