From 3efe7571c3ae2b6481253a2616c2bb3fbadd503b Mon Sep 17 00:00:00 2001 From: Nilay Shroff Date: Tue, 4 Mar 2025 15:52:34 +0530 Subject: block: protect nr_requests update using q->elevator_lock The sysfs attribute nr_requests could be simultaneously updated from elevator switch/update or nr_hw_queue update code path. The update to nr_requests for each of those code paths runs holding q->elevator_lock. So we should protect access to sysfs attribute nr_requests using q-> elevator_lock instead of q->sysfs_lock. Reviewed-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Reviewed-by: Ming Lei Signed-off-by: Nilay Shroff Link: https://lore.kernel.org/r/20250304102551.2533767-6-nilay@linux.ibm.com Signed-off-by: Jens Axboe --- include/linux/blkdev.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 31b1b635c710..3e66ad016a23 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -561,10 +561,12 @@ struct request_queue { struct list_head flush_list; /* - * Protects against I/O scheduler switching, specifically when - * updating q->elevator. To ensure proper locking order during - * an elevator update, first freeze the queue, then acquire - * ->elevator_lock. + * Protects against I/O scheduler switching, particularly when + * updating q->elevator. Since the elevator update code path may + * also modify q->nr_requests, this lock also protects the sysfs + * attribute nr_requests. + * To ensure proper locking order during an elevator update, first + * freeze the queue, then acquire ->elevator_lock. */ struct mutex elevator_lock; -- cgit v1.2.3