drm/i915: First recheck for an empty fence register.

If we wait upon a request and successfully unbind a buffer occupying a
fence register, then that slot will be freed and cause a NULL derefrence
upon rescanning.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index c94069b28a47..6497c1ad02d3 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1580,6 +1580,7 @@ i915_gem_object_get_fence_reg(struct drm_gem_object *obj, bool write)
         }
 
         /* First try to find a free reg */
+try_again:
         for (i = dev_priv->fence_reg_start; i < dev_priv->num_fence_regs; i++) {
                 reg = &dev_priv->fence_regs[i];
                 if (!reg->obj)
@@ -1591,7 +1592,6 @@ i915_gem_object_get_fence_reg(struct drm_gem_object *obj, bool write)
                 struct drm_i915_gem_object *old_obj_priv = NULL;
                 loff_t offset;
 
-try_again:
                 /* Could try to use LRU here instead... */
                 for (i = dev_priv->fence_reg_start;
                      i < dev_priv->num_fence_regs; i++) {