Re: [Intel-gfx] [PATCH 3/3] drm/i915: Warn when releasing a frontbuffer while in use

From: Chris Wilson <chris@chris-wilson.co.uk>
To: Ville Syrjala <ville.syrjala@linux.intel.com>,
	intel-gfx@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 3/3] drm/i915: Warn when releasing a frontbuffer while in use
Date: Tue, 09 Feb 2021 09:39:51 +0000	[thread overview]
Message-ID: <161286359136.7943.3112800560212828589@build.alporthouse.com> (raw)
In-Reply-To: <20210209021918.16234-3-ville.syrjala@linux.intel.com>

Quoting Ville Syrjala (2021-02-09 02:19:18)
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Let's scream if we are about to release a frontbuffer which
> is still in use.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_frontbuffer.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_frontbuffer.c b/drivers/gpu/drm/i915/display/intel_frontbuffer.c
> index 7b38eee9980f..6fc6965b6133 100644
> --- a/drivers/gpu/drm/i915/display/intel_frontbuffer.c
> +++ b/drivers/gpu/drm/i915/display/intel_frontbuffer.c
> @@ -224,6 +224,8 @@ static void frontbuffer_release(struct kref *ref)
>         struct drm_i915_gem_object *obj = front->obj;
>         struct i915_vma *vma;
>  
> +       drm_WARN_ON(obj->base.dev, atomic_read(&front->bits));

I had to double check the meaning of bits, and indeed they are cleared
by intel_frontbuffer_track as the scanout is switched away from the
object. A stacktrace here isn't particularly useful for tracking down
the leak, but it is a trivial method to make CI pay attention.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
-Chris
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