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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 enabled.
Link: https://lore.kernel.org/alsa-devel/YLeAvT+R22FQ%2FEyw@mwanda/
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
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