1 files changed, 1 insertions, 30 deletions

diff --git a/block/elevator.c b/block/elevator.c
index bba10e83478a..5437059c9261 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -503,9 +503,7 @@ int elv_register_queue(struct request_queue *q, bool uevent)
 		if (uevent)
 			kobject_uevent(&e->kobj, KOBJ_ADD);
 
-		mutex_lock(&q->sysfs_lock);
 		e->registered = 1;
-		mutex_unlock(&q->sysfs_lock);
 	}
 	return error;
 }
@@ -523,11 +521,9 @@ void elv_unregister_queue(struct request_queue *q)
 		kobject_uevent(&e->kobj, KOBJ_REMOVE);
 		kobject_del(&e->kobj);
 
-		mutex_lock(&q->sysfs_lock);
 		e->registered = 0;
 		/* Re-enable throttling in case elevator disabled it */
 		wbt_enable_default(q);
-		mutex_unlock(&q->sysfs_lock);
 	}
 }
 
@@ -590,32 +586,11 @@ int elevator_switch_mq(struct request_queue *q,
 	lockdep_assert_held(&q->sysfs_lock);
 
 	if (q->elevator) {
-		if (q->elevator->registered) {
-			mutex_unlock(&q->sysfs_lock);
-
-			/*
-			 * Concurrent elevator switch can't happen becasue
-			 * sysfs write is always exclusively on same file.
-			 *
-			 * Also the elevator queue won't be freed after
-			 * sysfs_lock is released becasue kobject_del() in
-			 * blk_unregister_queue() waits for completion of
-			 * .store & .show on its attributes.
-			 */
+		if (q->elevator->registered)
 			elv_unregister_queue(q);
 
-			mutex_lock(&q->sysfs_lock);
-		}
 		ioc_clear_queue(q);
 		elevator_exit(q, q->elevator);
-
-		/*
-		 * sysfs_lock may be dropped, so re-check if queue is
-		 * unregistered. If yes, don't switch to new elevator
-		 * any more
-		 */
-		if (!blk_queue_registered(q))
-			return 0;
 	}
 
 	ret = blk_mq_init_sched(q, new_e);
@@ -623,11 +598,7 @@ int elevator_switch_mq(struct request_queue *q,
 		goto out;
 
 	if (new_e) {
-		mutex_unlock(&q->sysfs_lock);
-
 		ret = elv_register_queue(q, true);
-
-		mutex_lock(&q->sysfs_lock);
 		if (ret) {
 			elevator_exit(q, q->elevator);
 			goto out;