[alsa-devel] [PATCH 1/8] ALSA: pcm: add a helper function to constrain mask-type parameters

[Takashi Sakamoto]

Hi,

On Jun 8 2017 16:10, Takashi Iwai wrote:
> On Thu, 08 Jun 2017 01:10:19 +0200,
> Takashi Sakamoto wrote:
>>
>> Application of constraints to mask-type parameters for PCM substream is
>> done in a call of snd_pcm_hw_refine(), while the function includes much
>> codes and is not enough friendly to readers.
>>
>> This commit splits the codes to a separated function so that readers can
>> get it easily. I leave desicion into compilers to merge the function into
>> its callee.
>>
>> Signed-off-by: Takashi Sakamoto <o-takashi at sakamocchi.jp>
>> ---
>>   sound/core/pcm_native.c | 57 ++++++++++++++++++++++++++++++++-----------------
>>   1 file changed, 38 insertions(+), 19 deletions(-)
>>
>> diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
>> index 2bde07a4a87f..b3e8aab3915e 100644
>> --- a/sound/core/pcm_native.c
>> +++ b/sound/core/pcm_native.c
>> ...
>> +	struct snd_mask __maybe_unused old_mask;
> 
> Do we really need __maybe_unused?  Drop it as much as possible.
> IMO, it can be uglier than ifdef, since you don't know why it's
> unused.  With ifdef, at least, you have an idea about the condition.

In kernel documentation[1], we can see below suggestion.

"20) Conditional Compilation
...
If you have a function or variable which may potentially go unused in a
particular configuration, and the compiler would warn about its 
definition going unused, mark the definition as __maybe_unused rather 
than wrapping it in a preprocessor conditional.  (However, if a function 
or variable *always* goes unused, delete it.)"

I'll follow this.


Regards

Takashi Sakamoto