diff mbox series

[V2,2/3] block: don't call freeze queue in elevator_switch() and elevator_disable()

Message ID 20250403025214.1274650-3-ming.lei@redhat.com (mailing list archive)
State New
Headers show
Series block: fix lock dependency between freeze and elevator lock | expand

Commit Message

Ming Lei April 3, 2025, 2:52 a.m. UTC 
Both elevator_switch() and elevator_disable() are called from sysfs
store and updating nr_hw_queue code paths only.

And in the two code paths, queue has been frozen already, so don't call
freeze queue in the two functions.

Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 block/elevator.c | 7 -------
 1 file changed, 7 deletions(-)

Comments

Christoph Hellwig April 3, 2025, 5:36 a.m. UTC | #1 
On Thu, Apr 03, 2025 at 10:52:09AM +0800, Ming Lei wrote:
> Both elevator_switch() and elevator_disable() are called from sysfs
> store and updating nr_hw_queue code paths only.
> 
> And in the two code paths, queue has been frozen already, so don't call
> freeze queue in the two functions.

This looks good, but please add asserts that the queue is in the
proper frozen state in both places.  Also please move it first as
it doesn't depend on the previous patch.
diff mbox series

Patch

diff --git a/block/elevator.c b/block/elevator.c
index b4d08026b02c..4d3a8f996c91 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -615,12 +615,10 @@  void elevator_init_mq(struct request_queue *q)
  */
 int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
 {
-	unsigned int memflags;
 	int ret;
 
 	lockdep_assert_held(&q->elevator_lock);
 
-	memflags = blk_mq_freeze_queue(q);
 	blk_mq_quiesce_queue(q);
 
 	if (q->elevator) {
@@ -641,7 +639,6 @@  int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
 
 out_unfreeze:
 	blk_mq_unquiesce_queue(q);
-	blk_mq_unfreeze_queue(q, memflags);
 
 	if (ret) {
 		pr_warn("elv: switch to \"%s\" failed, falling back to \"none\"\n",
@@ -653,11 +650,8 @@  int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
 
 void elevator_disable(struct request_queue *q)
 {
-	unsigned int memflags;
-
 	lockdep_assert_held(&q->elevator_lock);
 
-	memflags = blk_mq_freeze_queue(q);
 	blk_mq_quiesce_queue(q);
 
 	elv_unregister_queue(q);
@@ -668,7 +662,6 @@  void elevator_disable(struct request_queue *q)
 	blk_add_trace_msg(q, "elv switch: none");
 
 	blk_mq_unquiesce_queue(q);
-	blk_mq_unfreeze_queue(q, memflags);
 }
 
 /*