On Thu, May 13, 2021 at 10:15:29AM -0700, Bart Van Assche wrote:
> If a tag set is shared across request queues (e.g. SCSI LUNs) then the
> block layer core keeps track of the number of active request queues in
> tags->active_queues. blk_mq_tag_busy() and blk_mq_tag_idle() update that
> atomic counter if the hctx flag BLK_MQ_F_TAG_QUEUE_SHARED is set. Make
> sure that blk_mq_exit_queue() calls blk_mq_tag_idle() before that flag is
> cleared by blk_mq_del_queue_tag_set().
>
> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
> Cc: Ming Lei <ming.lei@xxxxxxxxxx>
> Cc: Hannes Reinecke <hare@xxxxxxxx>
> Fixes: 0d2602ca30e4 ("blk-mq: improve support for shared tags maps")
> Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
> ---
> block/blk-mq.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 1ea012de60eb..96b8e3164835 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -3289,10 +3289,12 @@ EXPORT_SYMBOL(blk_mq_init_allocated_queue);
> /* tags can _not_ be used after returning from blk_mq_exit_queue */
> void blk_mq_exit_queue(struct request_queue *q)
> {
> - struct blk_mq_tag_set *set = q->tag_set;
> + struct blk_mq_tag_set *set = q->tag_set;
>
> - blk_mq_del_queue_tag_set(q);
> + /* Checks hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED. */
> blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
> + /* May clear BLK_MQ_F_TAG_QUEUE_SHARED in hctx->flags. */
> + blk_mq_del_queue_tag_set(q);
> }
>
> static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
>
Looks fine:
Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
--
Ming
