On 4/30/25 06:35, Ming Lei wrote:
Prepare for moving elv_register[unregister]_queue out of elevator_lock & queue freezing, so we may have to call elv_unregister_queue() after elevator ->exit() is called, then there is small window for user to call into ->show()/store(), and user-after-free can be caused. Fail to show/store elevator sysfs attribute if elevator is dying by adding one new flag of ELEVATOR_FLAG_DYNG, which is protected by elevator ->sysfs_lock. Reviewed-by: Nilay Shroff <nilay@xxxxxxxxxxxxx> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> --- block/blk-mq-sched.c | 1 + block/elevator.c | 10 ++++++---- block/elevator.h | 1 + 3 files changed, 8 insertions(+), 4 deletions(-) diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c index 336a15ffecfa..55a0fd105147 100644 --- a/block/blk-mq-sched.c +++ b/block/blk-mq-sched.c @@ -551,5 +551,6 @@ void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e) if (e->type->ops.exit_sched) e->type->ops.exit_sched(e); blk_mq_sched_tags_teardown(q, flags); + set_bit(ELEVATOR_FLAG_DYING, &q->elevator->flags); q->elevator = NULL; }
set_bit() is unordered; don't you need to take ->sysfs_lock here? Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@xxxxxxx +49 911 74053 688 SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich
