[bug report] media: sound/usb: Use Media Controller API to share media resources

[Shuah Khan]

On 6/2/21 6:59 AM, Dan Carpenter wrote:
> Hello Shuah Khan,
> 
> The patch 66354f18fe5f: "media: sound/usb: Use Media Controller API
> to share media resources" from Apr 1, 2019, leads to the following
> static checker warning:
> 
> 	sound/usb/media.c:287 snd_media_device_create()
> 	warn: 'mdev' can also be NULL
> 
> sound/usb/media.c
>     270
>     271          mdev = media_device_usb_allocate(usbdev, KBUILD_MODNAME, THIS_MODULE);
>                  ^^^^
> 
> If CONFIG_MEDIA_CONTROLLER is disabled then "mdev" is NULL.

If CONFIG_MEDIA_CONTROLLER is disabled, this file won't be compiled.
Please see below clause in the Makefile.

sound/usb/Makefile:
snd-usb-audio-$(CONFIG_SND_USB_AUDIO_USE_MEDIA_CONTROLLER) += media.o

Also, this select in sound/usb/Kconfig selects appropriate
configs.

select SND_USB_AUDIO_USE_MEDIA_CONTROLLER if MEDIA_CONTROLLER && 
(MEDIA_SUPPORT=y || MEDIA_SUPPORT=SND_USB_AUDIO)

We are good here with the above in place to make sure media.c
code isn't in play when CONFIG_MEDIA_CONTROLLER is disabled.

thanks,
-- Shuah