Re: [PATCH 2/6] SCSI: use blk_mq_run_hw_queues() in scsi_kick_queue()

Bart Van Assche
2017-07-11T19:57:57Z

On Wed, 2017-07-12 at 02:20 +0800, Ming Lei wrote:
> Now SCSI won't stop queue, and not necessary to use
> blk_mq_start_hw_queues(), so switch to blk_mq_run_hw_queues()
> instead.
>=20
> Cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
> Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
> Cc: linux-scsi@vger.kernel.org
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
> drivers/scsi/scsi_lib.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index f6097b89d5d3..91d890356b78 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -333,7 +333,7 @@ void scsi_device_unbusy(struct scsi_device *sdev)
> static void scsi_kick_queue(struct request_queue *q)
> {
> if (q->mq_ops)
> - blk_mq_start_hw_queues(q);
> + blk_mq_run_hw_queues(q, false);
> else
> blk_run_queue(q);
> }

Hello Ming,

Now that we have separate flags to represent the "stopped" and "quiesced"
states, wouldn't it be better not to modify scsi_kick_queue() but instead t=
o
stop a SCSI hardware queue again if scsi_queue_rq() returns BLK_STS_RESOURC=
E?
See also commits 36e3cf273977 ("scsi: Avoid that SCSI queues get stuck") an=
d
commit 52d7f1b5c2f3 ("blk-mq: Avoid that requeueing starts stopped queues")=
.

Bart.=