drm/i915: fix unpaired i915 device mutex on entervt failure.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 4642115902d6..ee896d91c5bc 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4087,8 +4087,10 @@ i915_gem_entervt_ioctl(struct drm_device *dev, void *data,
         dev_priv->mm.suspended = 0;
 
         ret = i915_gem_init_ringbuffer(dev);
-        if (ret != 0)
+        if (ret != 0) {
+                mutex_unlock(&dev->struct_mutex);
                 return ret;
+        }
 
         spin_lock(&dev_priv->mm.active_list_lock);
         BUG_ON(!list_empty(&dev_priv->mm.active_list));