Re: [Intel-gfx] [PATCH v3] drm/i915: Warn on if set frontbuffer return value is not NULL on release

[Jani Nikula <jani.nikula@intel.com>]

On Thu, 28 Sep 2023, Jouni Högander <jouni.hogander@intel.com> wrote:
> i915_gem_object_set_frontbuffer returns set frontbuffer pointer.  When we
> are releasing frontbuffer we are clearing the pointer from the object. Warn
> on if return value is not null.
>
> v3: Check i915_gem_object_set_frontbuffer return value separately
> v2: Instead of ignoring do drm_WARN_ON
>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Cc: Jani Nikula <jani.nikula@intel.com>
>
> Signed-off-by: Jouni Högander <jouni.hogander@intel.com>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_frontbuffer.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_frontbuffer.c b/drivers/gpu/drm/i915/display/intel_frontbuffer.c
> index d5540c739404..412a19a888a2 100644
> --- a/drivers/gpu/drm/i915/display/intel_frontbuffer.c
> +++ b/drivers/gpu/drm/i915/display/intel_frontbuffer.c
> @@ -251,7 +251,7 @@ static void frontbuffer_retire(struct i915_active *ref)
>  static void frontbuffer_release(struct kref *ref)
>  	__releases(&intel_bo_to_i915(front->obj)->display.fb_tracking.lock)
>  {
> -	struct intel_frontbuffer *front =
> +	struct intel_frontbuffer *ret, *front =
>  		container_of(ref, typeof(*front), ref);
>  	struct drm_i915_gem_object *obj = front->obj;
>  
> @@ -259,7 +259,8 @@ static void frontbuffer_release(struct kref *ref)
>  
>  	i915_ggtt_clear_scanout(obj);
>  
> -	i915_gem_object_set_frontbuffer(obj, NULL);
> +	ret = i915_gem_object_set_frontbuffer(obj, NULL);
> +	drm_WARN_ON(&intel_bo_to_i915(obj)->drm, ret);
>  	spin_unlock(&intel_bo_to_i915(obj)->display.fb_tracking.lock);
>  
>  	i915_active_fini(&front->write);

-- 
Jani Nikula, Intel