Re: [PATCH 1/2] block: release q->elevator_lock in ioc_qos_write

[Ming Lei <ming.lei@redhat.com>]

On Wed, Mar 19, 2025 at 04:23:45PM +0530, Nilay Shroff wrote:
> The ioc_qos_write method acquires q->elevator_lock to protect
> updates to blk-wbt parameters. Once these updates are complete,
> the lock should be released before returning from ioc_qos_write.
> 
> However, in one code path, the release of q->elevator_lock was
> mistakenly omitted, potentially leading to a lock leak. This commit
> fixes the issue by ensuring that q->elevator_lock is properly
> released in all return paths of ioc_qos_write.
> 
> Fixes: 245618f8e45f ("block: protect wbt_lat_usec using q->elevator_lock")
> Reported-by: kernel test robot <oliver.sang@intel.com>
> Closes: https://lore.kernel.org/oe-lkp/202503171650.cc082b66-lkp@intel.com
> Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
> ---
>  block/blk-iocost.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/block/blk-iocost.c b/block/blk-iocost.c
> index 38e7bf3c3b4f..56e6fb51316d 100644
> --- a/block/blk-iocost.c
> +++ b/block/blk-iocost.c
> @@ -3348,6 +3348,7 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input,
>  		wbt_enable_default(disk);
>  
>  	blk_mq_unquiesce_queue(disk->queue);
> +	mutex_unlock(&disk->queue->elevator_lock);
>  	blk_mq_unfreeze_queue(disk->queue, memflags);

Reviewed-by: Ming Lei <ming.lei@redhat.com>


Thanks,
Ming