drm/i915: fix scheduling while holding the new active list spinlock

regression caused by commit 5e118f4139feafe97e913df67b1f7c1e5083e535:
i915_gem_object_move_to_inactive() should be called in task context,
as it calls fput();

Signed-off-by: Shaohua Li<shaohua.li@intel.com>
[anholt: Add more detail to the comment about the lock break that's added]
Signed-off-by: Eric Anholt <eric@anholt.net>

1 files changed, 12 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 6dca9fc7c1db..4642115902d6 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1596,8 +1596,19 @@ i915_gem_retire_request(struct drm_device *dev,
 
                 if (obj->write_domain != 0)
                         i915_gem_object_move_to_flushing(obj);
-                else
+                else {
+                        /* Take a reference on the object so it won't be
+                         * freed while the spinlock is held.  The list
+                         * protection for this spinlock is safe when breaking
+                         * the lock like this since the next thing we do
+                         * is just get the head of the list again.
+                         */
+                        drm_gem_object_reference(obj);
                         i915_gem_object_move_to_inactive(obj);
+                        spin_unlock(&dev_priv->mm.active_list_lock);
+                        drm_gem_object_unreference(obj);
+                        spin_lock(&dev_priv->mm.active_list_lock);
+                }
         }
 out:
         spin_unlock(&dev_priv->mm.active_list_lock);