Commit a72c374f authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: mark queue init done at the end of blk_register_queue 



Mark queue init done when everything is done well in blk_register_queue(),
so that wbt_enable_default() can be run quickly without any RCU period
involved since adding rq qos requires to freeze queue.

Also no any side effect by delaying to mark queue init done.

Reported-by: default avatarYi Zhang <yi.zhang@redhat.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Reviewed-by: default avatarBart Van Assche <bvanassche@acm.org>
Tested-by: default avatarYi Zhang <yi.zhang@redhat.com>
Link: https://lore.kernel.org/r/20210609015822.103433-3-ming.lei@redhat.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 2cafe29a

block/blk-sysfs.c

+15 −14
Original line number Diff line number Diff line
@@ -866,20 +866,6 @@ int blk_register_queue(struct gendisk *disk) 
		  "%s is registering an already registered queue\n",

		  kobject_name(&dev->kobj));



	/*

	 * SCSI probing may synchronously create and destroy a lot of

	 * request_queues for non-existent devices.  Shutting down a fully

	 * functional queue takes measureable wallclock time as RCU grace

	 * periods are involved.  To avoid excessive latency in these

	 * cases, a request_queue starts out in a degraded mode which is

	 * faster to shut down and is made fully functional here as

	 * request_queues for non-existent devices never get registered.

	 */

	if (!blk_queue_init_done(q)) {

		blk_queue_flag_set(QUEUE_FLAG_INIT_DONE, q);

		percpu_ref_switch_to_percpu(&q->q_usage_counter);

	}



	blk_queue_update_readahead(q);



	ret = blk_trace_init_sysfs(dev);
@@ -938,6 +924,21 @@ int blk_register_queue(struct gendisk *disk) 
	ret = 0;

unlock:

	mutex_unlock(&q->sysfs_dir_lock);



	/*

	 * SCSI probing may synchronously create and destroy a lot of

	 * request_queues for non-existent devices.  Shutting down a fully

	 * functional queue takes measureable wallclock time as RCU grace

	 * periods are involved.  To avoid excessive latency in these

	 * cases, a request_queue starts out in a degraded mode which is

	 * faster to shut down and is made fully functional here as

	 * request_queues for non-existent devices never get registered.

	 */

	if (!blk_queue_init_done(q)) {

		blk_queue_flag_set(QUEUE_FLAG_INIT_DONE, q);

		percpu_ref_switch_to_percpu(&q->q_usage_counter);

	}



	return ret;

}

EXPORT_SYMBOL_GPL(blk_register_queue);