blk_mq_run_queue() runs the queue asynchronously if BLK_MQ_F_BLOCKING
has been set. This is suboptimal since running the queue asynchronously
is slower than running the queue synchronously. This patch modifies
blk_mq_run_queue() as follows if BLK_MQ_F_BLOCKING has been set:
- Run the queue synchronously if it is allowed to sleep.
- Run the queue asynchronously if it is not allowed to sleep.
Additionally, blk_mq_run_hw_queue(hctx, false) calls are modified into
blk_mq_run_hw_queue(hctx, hctx->flags & BLK_MQ_F_BLOCKING) if the caller
may be invoked from atomic context.
The following caller chains have been reviewed:
blk_mq_run_hw_queue(hctx, false)
blk_mq_get_tag() /* may sleep, hence the functions it calls may also sleep */
blk_execute_rq() /* may sleep */
blk_mq_run_hw_queues(q, async=false)
blk_freeze_queue_start() /* may sleep */
blk_mq_requeue_work() /* may sleep */
scsi_kick_queue()
scsi_requeue_run_queue() /* may sleep */
scsi_run_host_queues()
scsi_ioctl_reset() /* may sleep */
blk_mq_insert_requests(hctx, ctx, list, run_queue_async=false)
blk_mq_dispatch_plug_list(plug, from_sched=false)
blk_mq_flush_plug_list(plug, from_schedule=false)
__blk_flush_plug(plug, from_schedule=false)
blk_add_rq_to_plug()
blk_mq_submit_bio() /* may sleep if REQ_NOWAIT has not been set */
blk_mq_plug_issue_direct()
blk_mq_flush_plug_list() /* see above */
blk_mq_dispatch_plug_list(plug, from_sched=false)
blk_mq_flush_plug_list() /* see above */
blk_mq_try_issue_directly()
blk_mq_submit_bio() /* may sleep if REQ_NOWAIT has not been set */
blk_mq_try_issue_list_directly(hctx, list)
blk_mq_insert_requests() /* see above */
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20230721172731.955724-4-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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