[Intel-gfx] [PATCH 1/2] drm/i915: introduce GEM_WARN_ON

[Matthew Auld]

On 13 December 2016 at 16:25, Joonas Lahtinen
<joonas.lahtinen at linux.intel.com> wrote:
> On ti, 2016-12-13 at 16:00 +0000, Matthew Auld wrote:
>> In a similar spirit to GEM_BUG_ON we now also have GEM_WARN_ON, with the
>> simple goal of expressing warnings which are truly insane, and so are
>> only really useful for CI where we have some abusive tests.
>>
>> v2:
>>   - use BUILD_BUG_ON_INVALID for !DEBUG_GEM
>>   - clarify commit message
>>
>> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
>> Cc: Chris Wilson <chris at chris-wilson.co.uk>
>> Suggested-by: Chris Wilson <chris at chris-wilson.co.uk>
>> Signed-off-by: Matthew Auld <matthew.auld at intel.com>
>
> <SNIP>
>
>> +++ b/drivers/gpu/drm/i915/i915_gem.h
>> @@ -27,8 +27,10 @@
>>
>>  #ifdef CONFIG_DRM_I915_DEBUG_GEM
>>  #define GEM_BUG_ON(expr) BUG_ON(expr)
>> +#define GEM_WARN_ON(expr) WARN_ON(expr)
>>  #else
>>  #define GEM_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr)
>> +#define GEM_WARN_ON(expr) (BUILD_BUG_ON_INVALID(expr), 0)
>
> +#define GEM_WARN_ON(expr) GEM_BUG_ON(expr)
>
> Should be enough in the #else branch just like in linux/mmdebug.h
BUILD_BUG_INVALID(expr) will do a (void) cast to discard the result of
the sizeof operation, but then we don't end up ignoring said result if
we use it in the context of an if condition, which will make the
compiler very unhappy.