i915-gpu-finish.patch

commit 389a55581e30607af0fcde6cdb4e54f189cf46cf
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Tue Nov 29 15:12:16 2011 +0000

    drm/i915: Only clear the GPU domains upon a successful finish
    
    By clearing the GPU read domains before waiting upon the buffer, we run
    the risk of the wait being interrupted and the domains prematurely
    cleared. The next time we attempt to wait upon the buffer (after
    userspace handles the signal), we believe that the buffer is idle and so
    skip the wait.
    
    There are a number of bugs across all generations which show signs of an
    overly haste reuse of active buffers.
    
    Such as:
    
      https://bugs.freedesktop.org/show_bug.cgi?id=29046
      https://bugs.freedesktop.org/show_bug.cgi?id=35863
      https://bugs.freedesktop.org/show_bug.cgi?id=38952
      https://bugs.freedesktop.org/show_bug.cgi?id=40282
      https://bugs.freedesktop.org/show_bug.cgi?id=41098
      https://bugs.freedesktop.org/show_bug.cgi?id=41102
      https://bugs.freedesktop.org/show_bug.cgi?id=41284
      https://bugs.freedesktop.org/show_bug.cgi?id=42141
    
    A couple of those pre-date i915_gem_object_finish_gpu(), so may be
    unrelated (such as a wild write from a userspace command buffer), but
    this does look like a convincing cause for most of those bugs.
    
    Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
    Cc: stable@kernel.org
    Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
    Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index d560175..036bc58 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3087,10 +3087,13 @@ i915_gem_object_finish_gpu(struct drm_i915_gem_object *obj)
 			return ret;
 	}
 
+	ret = i915_gem_object_wait_rendering(obj);
+	if (ret)
+		return ret;
+
 	/* Ensure that we invalidate the GPU's caches and TLBs. */
 	obj->base.read_domains &= ~I915_GEM_GPU_DOMAINS;
-
-	return i915_gem_object_wait_rendering(obj);
+	return 0;
 }
 
 /**