From: Shuah Khan <skhan@linuxfoundation.org>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: alsa-devel@alsa-project.org, shuah@kernel.org,
Shuah Khan <skhan@linuxfoundation.org>
Subject: Re: [bug report] media: sound/usb: Use Media Controller API to share media resources
Date: Tue, 8 Jun 2021 13:49:13 -0600 [thread overview]
Message-ID: <11ad1173-4b37-3bb9-6435-f8d7321921af@linuxfoundation.org> (raw)
In-Reply-To: <20210608190309.GJ10983@kadam>
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
prev parent reply other threads:[~2021-06-08 19:50 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-02 12:59 [bug report] media: sound/usb: Use Media Controller API to share media resources Dan Carpenter
2021-06-08 17:53 ` Shuah Khan
2021-06-08 19:03 ` Dan Carpenter
2021-06-08 19:49 ` Shuah Khan [this message]
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