Re: [PATCH] media: Fix Media Controller API config checks

[Shuah Khan]

On 6/15/21 7:36 AM, Hans Verkuil wrote:
> Hi Shuah,
>
> On 11/06/2021 03:58, Shuah Khan wrote:
> > Smatch static checker warns that "mdev" can be null:
> >
> > sound/usb/media.c:287 snd_media_device_create()
> >      warn: 'mdev' can also be NULL
> >
> > If CONFIG_MEDIA_CONTROLLER is disabled, this file should not be included
> > in the build.
> >
> > The below conditions in the sound/usb/Makefile are in place to ensure that
> > media.c isn't included in the build.
> >
> > sound/usb/Makefile:
> > snd-usb-audio-$(CONFIG_SND_USB_AUDIO_USE_MEDIA_CONTROLLER) += media.o
> >
> > select SND_USB_AUDIO_USE_MEDIA_CONTROLLER if MEDIA_CONTROLLER &&
> >         (MEDIA_SUPPORT=y || MEDIA_SUPPORT=SND_USB_AUDIO)
> >
> > The following config check in include/media/media-dev-allocator.h is
> > in place to enable the API only when CONFIG_MEDIA_CONTROLLER and
> > CONFIG_USB are enabled.
> >
> >   #if defined(CONFIG_MEDIA_CONTROLLER) && defined(CONFIG_USB)
> >
> > This check doesn't work as intended when CONFIG_USB=m. When CONFIG_USB=m,
> > CONFIG_USB_MODULE is defined and CONFIG_USB is not. The above config check
> > doesn't catch that CONFIG_USB is defined as a module and disables the API.
> > This results in sound/usb enabling Media Controller specific ALSA driver
> > code, while Media disables the Media Controller API.
> >
> > Fix the problem requires two changes:
> >
> > 1. Change the check to use IS_ENABLED to detect when CONFIG_USB is enabled
> >     as a module or static. Since CONFIG_MEDIA_CONTROLLER is a bool, leave
> >     the check unchanged to be consistent with drivers/media/Makefile.
> >
> > 2. Change the drivers/media/mc/Makefile to include mc-dev-allocator.o
> >     in mc-objs when CONFIG_USB is y or m.
>
> If I test this patch, then I get:
>
> drivers/media/mc/mc-dev-allocator.c:97:22: error: redefinition of 'media_device_usb_allocate'
>     97 | struct media_device *media_device_usb_allocate(struct usb_device *udev,
>        |                      ^~~~~~~~~~~~~~~~~~~~~~~~~
> In file included from drivers/media/mc/mc-dev-allocator.c:24:
> include/media/media-dev-allocator.h:55:36: note: previous definition of 'media_device_usb_allocate' was here
>     55 | static inline struct media_device *media_device_usb_allocate(
>        |                                    ^~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/media/mc/mc-dev-allocator.c:119:6: error: redefinition of 'media_device_delete'
>    119 | void media_device_delete(struct media_device *mdev, const char *module_name,
>        |      ^~~~~~~~~~~~~~~~~~~
> In file included from drivers/media/mc/mc-dev-allocator.c:24:
> include/media/media-dev-allocator.h:59:20: note: previous definition of 'media_device_delete' was here
>     59 | static inline void media_device_delete(
>        |                    ^~~~~~~~~~~~~~~~~~~
>
> The .config has:
>
> # CONFIG_USB_SUPPORT is not set
> CONFIG_MEDIA_CONTROLLER=y
Oops. I tried different combinations of CONFIG_USB and didn't try this
one. Will send v2.

thanks,
-- Shuah