drm/prime: fix error path deadlock fail

There were a couple messed up things about this fail path.
(1) it would drop object_name_lock twice
(2) drm_gem_handle_delete() (in drm_gem_remove_prime_handles())
    needs to grab prime_lock

Reported-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1465500559-17873-1-git-send-email-robdclark@gmail.com

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index aab0f3f1f42d..780589b420a4 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -593,7 +593,7 @@ int drm_gem_prime_fd_to_handle(struct drm_device *dev,
                 get_dma_buf(dma_buf);
         }
 
-        /* drm_gem_handle_create_tail unlocks dev->object_name_lock. */
+        /* _handle_create_tail unconditionally unlocks dev->object_name_lock. */
         ret = drm_gem_handle_create_tail(file_priv, obj, handle);
         drm_gem_object_unreference_unlocked(obj);
         if (ret)
@@ -601,11 +601,10 @@ int drm_gem_prime_fd_to_handle(struct drm_device *dev,
 
         ret = drm_prime_add_buf_handle(&file_priv->prime,
                         dma_buf, *handle);
+        mutex_unlock(&file_priv->prime.lock);
         if (ret)
                 goto fail;
 
-        mutex_unlock(&file_priv->prime.lock);
-
         dma_buf_put(dma_buf);
 
         return 0;
@@ -615,11 +614,14 @@ fail:
          * to detach.. which seems ok..
          */
         drm_gem_handle_delete(file_priv, *handle);
+        dma_buf_put(dma_buf);
+        return ret;
+
 out_unlock:
         mutex_unlock(&dev->object_name_lock);
 out_put:
-        dma_buf_put(dma_buf);
         mutex_unlock(&file_priv->prime.lock);
+        dma_buf_put(dma_buf);
         return ret;
 }
 EXPORT_SYMBOL(drm_gem_prime_fd_to_handle);