Re: [PATCH] uapi: fix linux/usb/audio.h userspace compilation error

[Takashi Iwai]

On Mon, 13 Aug 2018 17:46:51 +0200,
Dmitry V. Levin wrote:
> 
> Replace NULL with 0 in uac_mixer_unit_bmControls() to fix the following
> linux/usb/audio.h userspace compilation error:
> 
> /usr/include/linux/usb/audio.h: In function 'uac_mixer_unit_bmControls':
> /usr/include/linux/usb/audio.h:304:10: error: 'NULL' undeclared (first use in this function)
>    return NULL;
> 
> Fixes: 6cfd839ae78e ("ALSA: usb-audio: UAC3. Add support for mixer unit.")
> Cc: <stable@xxxxxxxxxxxxxxx> # v4.18
> Signed-off-by: Dmitry V. Levin <ldv@xxxxxxxxxxxx>

Hrm, can we include the standard header for definition of NULL
instead?  It's way too ugly to use 0 just for that.


thanks,

Takashi

> ---
>  include/uapi/linux/usb/audio.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/uapi/linux/usb/audio.h b/include/uapi/linux/usb/audio.h
> index 74e520fb944f..2b61fe34b2ca 100644
> --- a/include/uapi/linux/usb/audio.h
> +++ b/include/uapi/linux/usb/audio.h
> @@ -301,7 +301,7 @@ static inline __u8 *uac_mixer_unit_bmControls(struct uac_mixer_unit_descriptor *
>  	case UAC_VERSION_3:
>  		return &desc->baSourceID[desc->bNrInPins + 2];
>  	default:
> -		return NULL;
> +		return 0;
>  	}
>  }
>  
> -- 
> ldv
>