linux-kernel - Re: [PATCH] ALSA:usb-audio:check urb before kill it

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Date:   Tue, 29 Dec 2020 09:25:48 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     Defang Bo <bodefang@....com>
Cc:     perex@...ex.cz, tiwai@...e.com, tom.ty89@...il.com,
        kai.heng.feng@...onical.com, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ALSA:usb-audio:check urb before kill it

On Sun, 27 Dec 2020 14:04:59 +0100,
Defang Bo wrote:
> 
> Similar to commit<124751d5e>, there should be a check for urb before kill it.
> 
> Signed-off-by: Defang Bo <bodefang@....com>

usb_kill_urb() accepts the NULL urb pointer, so the NULL check in the
caller side is basically superfluous.


thanks,

Takashi

> ---
>  sound/usb/mixer.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> index 81e987e..0223ef3 100644
> --- a/sound/usb/mixer.c
> +++ b/sound/usb/mixer.c
> @@ -3589,8 +3589,10 @@ void snd_usb_mixer_disconnect(struct usb_mixer_interface *mixer)
>  /* stop any bus activity of a mixer */
>  static void snd_usb_mixer_inactivate(struct usb_mixer_interface *mixer)
>  {
> -	usb_kill_urb(mixer->urb);
> -	usb_kill_urb(mixer->rc_urb);
> +	if (mixer->urb)
> +		usb_kill_urb(mixer->urb);
> +	if (mixer->rc_urb)
> +		usb_kill_urb(mixer->rc_urb);
>  }
>  
>  static int snd_usb_mixer_activate(struct usb_mixer_interface *mixer)
> -- 
> 2.7.4
>