[PATCH 06/25] vmwgfx: Some comments and BUG_ON

[Thomas Hellstrom]

From: Jakob Bornecrantz <jakob at vmware.com>

Signed-off-by: Jakob Bornecrantz <jakob at vmware.com>
Reviewed-by: Thomas Hellstrom <thellstrom at vmware.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
index df1c7c5..207f595 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
@@ -680,6 +680,9 @@ 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 not NULL. Creates
+ * a userspace handle if @p_handle is not NULL, does not if otherwise.
  */
 
 int vmw_execbuf_fence_commands(struct drm_file *file_priv,
@@ -691,6 +694,8 @@ 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)) {
-- 
1.7.4.4