On 9/3/24 11:30 PM, Dmitry Torokhov wrote:
> Using guard notation makes the code more compact and error handling
> more robust by ensuring that mutexes are released in all code paths
> when control leaves critical section.
>
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> ---
> drivers/input/joystick/db9.c | 30 ++++++++++++++----------------
> 1 file changed, 14 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/input/joystick/db9.c b/drivers/input/joystick/db9.c
> index 682a29c27832..7ac0cfc3e786 100644
> --- a/drivers/input/joystick/db9.c
> +++ b/drivers/input/joystick/db9.c
> @@ -505,24 +505,22 @@ static int db9_open(struct input_dev *dev)
> {
> struct db9 *db9 = input_get_drvdata(dev);
> struct parport *port = db9->pd->port;
> - int err;
>
> - err = mutex_lock_interruptible(&db9->mutex);
> - if (err)
> - return err;
> -
> - if (!db9->used++) {
> - parport_claim(db9->pd);
> - parport_write_data(port, 0xff);
> - if (db9_modes[db9->mode].reverse) {
> - parport_data_reverse(port);
> - parport_write_control(port, DB9_NORMAL);
> + scoped_guard(mutex_intr, &db9->mutex) {
> + if (!db9->used++) {
> + parport_claim(db9->pd);
> + parport_write_data(port, 0xff);
> + if (db9_modes[db9->mode].reverse) {
> + parport_data_reverse(port);
> + parport_write_control(port, DB9_NORMAL);
> + }
> + mod_timer(&db9->timer, jiffies + DB9_REFRESH_TIME);
> }
> - mod_timer(&db9->timer, jiffies + DB9_REFRESH_TIME);
> +
> + return 0;
> }
>
> - mutex_unlock(&db9->mutex);
> - return 0;
> + return -EINTR;
This patch and any others like it are potentially introducing a bug.
