On Tue, 23 May 2017, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote:
> On Tue, May 23, 2017 at 10:19:31AM +0100, Tvrtko Ursulin wrote:
>> From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
>>
>> Waiting for engines needs to happen even in the non-debug builds
>> so it is incorrect to wrap it in a GEM_WARN_ON.
>>
>> Call it unconditionally and add GEM_WARN so that the debug
>> warning can still be emitted when things go bad.
>>
>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
>> Fixes: 25112b64b3d2 ("drm/i915: Wait for all engines to be idle as part of i915_gem_wait_for_idle()")
>> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
>> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
>> Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
>> Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
>> Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
>> Reported-by: Nick Desaulniers <nick.desaulniers@xxxxxxxxx>
>> Cc: Nick Desaulniers <nick.desaulniers@xxxxxxxxx>
>> ---
>> drivers/gpu/drm/i915/i915_gem.c | 3 ++-
>> drivers/gpu/drm/i915/i915_gem.h | 2 ++
>> 2 files changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
>> index a637cc05cc4a..ecaa21f106c8 100644
>> --- a/drivers/gpu/drm/i915/i915_gem.c
>> +++ b/drivers/gpu/drm/i915/i915_gem.c
>> @@ -3332,7 +3332,8 @@ static int wait_for_engines(struct drm_i915_private *i915)
>> enum intel_engine_id id;
>>
>> for_each_engine(engine, i915, id) {
>> - if (GEM_WARN_ON(wait_for_engine(engine, 50))) {
>> + if (wait_for_engine(engine, 50)) {
>> + GEM_WARN(1, "%s wait for idle timeout", engine->name);
>
> Nice touching adding the engine->name
> Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
>
>> i915_gem_set_wedged(i915);
>> return -EIO;
>> }
>> diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h
>> index ee54597465b6..cefc6cf96a60 100644
>> --- a/drivers/gpu/drm/i915/i915_gem.h
>> +++ b/drivers/gpu/drm/i915/i915_gem.h
>> @@ -30,6 +30,7 @@
>> #ifdef CONFIG_DRM_I915_DEBUG_GEM
>> #define GEM_BUG_ON(expr) BUG_ON(expr)
>> #define GEM_WARN_ON(expr) WARN_ON(expr)
>> +#define GEM_WARN(condition, format, ...) WARN(condition, format, __VA_ARGS__)
>>
>> #define GEM_DEBUG_DECL(var) var
>> #define GEM_DEBUG_EXEC(expr) expr
>> @@ -38,6 +39,7 @@
>> #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(condition, format, ...) BUILD_BUG_ON_INVALID(condition)
>
> WARNs can be used as part of an if(), so perhaps
>
> #define GEM_WARN(condition, format, ...) (BUILD_BUG_ON_INVALID(condition), 0)
> #define GEM_WARN_ON(expr) GEM_WARN((expr), 0)
Sorry, I just can't resist the "told you so" here.
If you come up with a local pattern that's deceptively similar to a
widely used one, with the crucial difference that you can't use anything
with required side effects in it, you'll screw it up eventually.
if (GEM_WARN_ON(wait_for_engine(engine, 50))) looks completely natural
and "obviously correct" in code, but is dead wrong. This won't be the
last time.
BR,
Jani.
--
Jani Nikula, Intel Open Source Technology Center
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