Re: [PATCH 1/6] xen-blkfront: avoid to use start/stop queue

Konrad Rzeszutek Wilk
2017-07-11T18:41:55Z

On Wed, Jul 12, 2017 at 02:20:58AM +0800, Ming Lei wrote:
> This interfaces will be removed soon, so use quiesce and
> unquiesce instead, which should be more safe.

'should be'? That does not sound encouraging?

>
> The only one usage will be removed in the following
> congestion control patches.
>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: "Roger Pau Monnï¿½" <roger.pau@citrix.com>
> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Cc: Juergen Gross <jgross@suse.com>
> Cc: xen-devel@lists.xenproject.org
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
> drivers/block/xen-blkfront.c | 22 ++++++++--------------
> 1 file changed, 8 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> index c852ed3c01d5..1578befda635 100644
> --- a/drivers/block/xen-blkfront.c
> +++ b/drivers/block/xen-blkfront.c
> @@ -1187,7 +1187,7 @@ static void xlvbd_release_gendisk(struct blkfront_info *info)
> return;
>
> /* No more blkif_request(). */
> - blk_mq_stop_hw_queues(info->rq);
> + blk_mq_quiesce_queue(info->rq);
>
> for (i = 0; i < info->nr_rings; i++) {
> struct blkfront_ring_info *rinfo = &info->rinfo[i];
> @@ -1216,8 +1216,10 @@ static void xlvbd_release_gendisk(struct blkfront_info *info)
> /* Already hold rinfo->ring_lock. */
> static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
> {
> - if (!RING_FULL(&rinfo->ring))
> + if (!RING_FULL(&rinfo->ring)) {
> blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
> + blk_mq_kick_requeue_list(rinfo->dev_info->rq);
> + }
> }
>
> static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
> @@ -1225,7 +1227,8 @@ static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
> unsigned long flags;
>
> spin_lock_irqsave(&rinfo->ring_lock, flags);
> - kick_pending_request_queues_locked(rinfo);
> + if (!RING_FULL(&rinfo->ring))
> + blk_mq_run_hw_queues(rinfo->dev_info->rq, true);
> spin_unlock_irqrestore(&rinfo->ring_lock, flags);
> }
>
> @@ -1346,7 +1349,7 @@ static void blkif_free(struct blkfront_info *info, int suspend)
> BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
> /* No more blkif_request(). */
> if (info->rq)
> - blk_mq_stop_hw_queues(info->rq);
> + blk_mq_quiesce_queue(info->rq);
>
> for (i = 0; i < info->nr_rings; i++)
> blkif_free_ring(&info->rinfo[i]);
> @@ -2018,22 +2021,13 @@ static int blkif_recover(struct blkfront_info *info)
> /* Now safe for us to use the shared ring */
> info->connected = BLKIF_STATE_CONNECTED;
>
> - for (r_index = 0; r_index < info->nr_rings; r_index++) {
> - struct blkfront_ring_info *rinfo;
> -
> - rinfo = &info->rinfo[r_index];
> - /* Kick any other new requests queued since we resumed */
> - kick_pending_request_queues(rinfo);
> - }
> -
> list_for_each_entry_safe(req, n, &info->requests, queuelist) {
> /* Requeue pending requests (flush or discard) */
> list_del_init(&req->queuelist);
> BUG_ON(req->nr_phys_segments > segs);
> blk_mq_requeue_request(req, false);
> }
> - blk_mq_start_stopped_hw_queues(info->rq, true);
> - blk_mq_kick_requeue_list(info->rq);
> + blk_mq_unquiesce_queue(info->rq);
>
> while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
> /* Traverse the list of pending bios and re-queue them */
> --
> 2.9.4
>