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media: Fix Media Controller API config checks 

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>
This commit is contained in:
Shuah Khan 2021-06-16 17:19:06 +02:00 committed by Mauro Carvalho Chehab
parent 198bb646e8
commit 50e7a31d30
2 changed files with 2 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/media/mc/Makefile
View File

@ -3,7 +3,7 @@
mc-objs := mc-device.o mc-devnode.o mc-entity.o \
mc-request.o
ifeq ($(CONFIG_USB),y)
ifneq ($(CONFIG_USB),)
mc-objs += mc-dev-allocator.o
endif

2
include/media/media-dev-allocator.h
View File

@ -19,7 +19,7 @@
struct usb_device;
#if defined(CONFIG_MEDIA_CONTROLLER) && defined(CONFIG_USB)
#if defined(CONFIG_MEDIA_CONTROLLER) && IS_ENABLED(CONFIG_USB)
/**
* media_device_usb_allocate() - Allocate and return struct &media device
*