On Tue, Jun 08, 2021 at 11:53:53AM -0600, Shuah Khan wrote:
> 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.
Smatch is working based on a real .config but I misunderstood the
problem.
include/media/media-dev-allocator.h
21
22 #if defined(CONFIG_MEDIA_CONTROLLER) && defined(CONFIG_USB)
^^^^^^^^^^^^^^^^^^^
When I have CONFIG_USB=m then this is false, but when I use CONFIG_USB=y
then this is true. I'm not an expert on the kernel build system so I
can't explain why defined() is not working as expected but I know that
if we used IS_ENABLED(CONFIG_USB) that would work.
#if IS_ENABLED(CONFIG_MEDIA_CONTROLLER) && IS_ENABLED)CONFIG_USB)
23 /**
24 * media_device_usb_allocate() - Allocate and return struct &media device
25 *
26 * @udev: struct &usb_device pointer
27 * @module_name: should be filled with %KBUILD_MODNAME
28 * @owner: struct module pointer %THIS_MODULE for the driver.
29 * %THIS_MODULE is null for a built-in driver.
30 * It is safe even when %THIS_MODULE is null.
31 *
32 * This interface should be called to allocate a Media Device when multiple
33 * drivers share usb_device and the media device. This interface allocates
34 * &media_device structure and calls media_device_usb_init() to initialize
35 * it.
36 *
37 */
38 struct media_device *media_device_usb_allocate(struct usb_device *udev,
39 const char *module_name,
40 struct module *owner);
regards,
dan carpenter
