On 6/8/21 1:03 PM, Dan Carpenter wrote:
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)
Good find. IS_ENABLED is the right usage. When CONFIG_USB=m,
CONFIG_USB_MODULE is defined and CONFIG_USB isn't.
IS_ENABLED does the following and catches both, where as defined()
checks just for CONFIG_USB.
include/linux/kconfig.h 71
#define IS_ENABLED(option) __or(IS_BUILTIN(option), IS_MODULE(option))
I will send patch to fix this. Thanks for finding it.
thanks,
-- Shuah
