[Intel-gfx] [PATCH] drm/i915: Mark expected switch fall-throughs

[Daniel Vetter]

On Mon, Dec 4, 2017 at 4:20 PM, Gustavo A. R. Silva
<garsilva at embeddedor.com> wrote:
> Hi Joonas,
>
> Quoting Joonas Lahtinen <joonas.lahtinen at linux.intel.com>:
>
>> On Mon, 2017-11-27 at 16:17 -0600, Gustavo A. R. Silva wrote:
>>>
>>> In preparation to enabling -Wimplicit-fallthrough, mark switch cases
>>> where we are expecting to fall through.
>>
>>
>> I have to say I'm totally not sold on regexps matching comment
>> contents. Was something more explicit ever considered? Like:
>>
>> #define FALLTHROUGH __attribute__((fallthrough));
>>
>> With the appropriate version checks, of course.
>>
>
> One of the arguments is that comments lets us leverage the existing static
> analyzers.
>
> We've been discussing this during the last week, feel free to join the
> discussion:
>
> http://www.spinics.net/lists/kernel/msg2659908.html
> http://www.spinics.net/lists/kernel/msg2659906.html

If we go with existing rules, then either pls patch coding style, or
be a bit more liberal in what you accept. E.g. fallthrough vs fall
through seems a bit a bikeshed (and will be an endless source of work
for you).

I'd also claim that "this shouldn't happen, dump a backtrace and hope
for the best" style macros like i915's MISSING_CASE or WARN_ON (as the
only thing) should count as an auto-fallthrough annotation.

>From a quick look, that would cover everything in your patch.
-Daniel

>
> Thanks!
> --
> Gustavo A. R. Silva
>
>
>
>
>
>
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch