vmwgfx: Some comments and BUG_ON

Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
index fa26e64..cc8c08b 100644 (file)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
@@ -681,6 +681,9 @@ static int vmw_resize_cmd_bounce(struct vmw_sw_context *sw_context,
  * Creates a fence object and submits a command stream marker.
  * If this fails for some reason, We sync the fifo and return NULL.
  * It is then safe to fence buffers with a NULL pointer.
+ *
+ * If @p_handle is not NULL @file_priv must also not be NULL. Creates
+ * a userspace handle if @p_handle is not NULL, otherwise not.
  */
 
 int vmw_execbuf_fence_commands(struct drm_file *file_priv,
@@ -692,6 +695,8 @@ int vmw_execbuf_fence_commands(struct drm_file *file_priv,
        int ret;
        bool synced = false;
 
+       /* p_handle implies file_priv. */
+       BUG_ON(p_handle != NULL && file_priv == NULL);
 
        ret = vmw_fifo_send_fence(dev_priv, &sequence);
        if (unlikely(ret != 0)) {