[PATCH v4 1/3] block: simplify calling convention of elv_unregister_queue()

[Eric Biggers]

From: Eric Biggers <ebiggers@xxxxxxxxxx>

Make elv_unregister_queue() a no-op if q->elevator is NULL or is not
registered.

This simplifies the existing callers, as well as the future caller in
the error path of blk_register_queue().

Also don't bother checking whether q is NULL, since it never is.

Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
 block/blk-sysfs.c | 3 +--
 block/elevator.c  | 8 ++++----
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 9f32882ceb2f6..a02b42ad9a6e0 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -960,8 +960,7 @@ void blk_unregister_queue(struct gendisk *disk)
 	blk_trace_remove_sysfs(disk_to_dev(disk));
 
 	mutex_lock(&q->sysfs_lock);
-	if (q->elevator)
-		elv_unregister_queue(q);
+	elv_unregister_queue(q);
 	disk_unregister_independent_access_ranges(disk);
 	mutex_unlock(&q->sysfs_lock);
 	mutex_unlock(&q->sysfs_dir_lock);
diff --git a/block/elevator.c b/block/elevator.c
index ec98aed39c4f5..b062c5bc10b9a 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -516,9 +516,11 @@ int elv_register_queue(struct request_queue *q, bool uevent)
 
 void elv_unregister_queue(struct request_queue *q)
 {
+	struct elevator_queue *e = q->elevator;
+
 	lockdep_assert_held(&q->sysfs_lock);
 
-	if (q) {
+	if (e && e->registered) {
 		struct elevator_queue *e = q->elevator;
 
 		kobject_uevent(&e->kobj, KOBJ_REMOVE);
@@ -593,9 +595,7 @@ int elevator_switch_mq(struct request_queue *q,
 	lockdep_assert_held(&q->sysfs_lock);
 
 	if (q->elevator) {
-		if (q->elevator->registered)
-			elv_unregister_queue(q);
-
+		elv_unregister_queue(q);
 		ioc_clear_queue(q);
 		blk_mq_sched_free_rqs(q);
 		elevator_exit(q);
-- 
2.34.1