staging: sync: Reorder sync_fence_release

Previously fence's pts were freed before the were the fence was removed from the
global fence list.  This led to a race with the debugfs support where it would
iterate over sync_pts that had been freed.

Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Cc: Erik Gilling <konkers@android.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Rob Clark <robclark@gmail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: dri-devel@lists.freedesktop.org
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Erik Gilling <konkers@android.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/android/sync.c

@@ -520,12 +520,12 @@ static int sync_fence_release(struct inode *inode, struct file *file)
 	struct sync_fence *fence = file->private_data;
 	unsigned long flags;
 
-	sync_fence_free_pts(fence);
-
 	spin_lock_irqsave(&sync_fence_list_lock, flags);
 	list_del(&fence->sync_fence_list);
 	spin_unlock_irqrestore(&sync_fence_list_lock, flags);
 
+	sync_fence_free_pts(fence);
+
 	kfree(fence);
 
 	return 0;