Re: [PATCH] trace/blktrace: fix memory leak with using debugfs_lookup()

[Bart Van Assche]

On 2/2/23 06:19, Greg Kroah-Hartman wrote:
> When calling debugfs_lookup() the result must have dput() called on it,
> otherwise the memory will leak over time.  To make things simpler, just
> call debugfs_lookup_and_remove() instead which handles all of the logic
> at once.
>
> Cc: Jens Axboe <axboe@xxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Cc: linux-block@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: linux-trace-kernel@xxxxxxxxxxxxxxx
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
>   kernel/trace/blktrace.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
> index 918a7d12df8f..5743be559415 100644
> --- a/kernel/trace/blktrace.c
> +++ b/kernel/trace/blktrace.c
> @@ -320,8 +320,8 @@ static void blk_trace_free(struct request_queue *q, struct blk_trace *bt)
>   	 * under 'q->debugfs_dir', thus lookup and remove them.
>   	 */
>   	if (!bt->dir) {
> -		debugfs_remove(debugfs_lookup("dropped", q->debugfs_dir));
> -		debugfs_remove(debugfs_lookup("msg", q->debugfs_dir));
> +		debugfs_lookup_and_remove("dropped", q->debugfs_dir);
> +		debugfs_lookup_and_remove("msg", q->debugfs_dir);
>   	} else {
>   		debugfs_remove(bt->dir);
>   	}

Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>