[PATCH v2 1/5] drm/vmwgfx: Add some checks to vmw_cursor_plane_atomic_update

[Maaz Mombasawala <maaz.mombasawala@broadcom.com>]

In cases where old_state may not be present we hit a null dereference.
Add a check to fix this and also do an early return if there is no
new_state or crtc since there is nothing to do in that case.
This fixes igt test kms_cursor_legacy@torture-bo.

Signed-off-by: Maaz Mombasawala <maaz.mombasawala@broadcom.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_cursor_plane.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_cursor_plane.c b/drivers/gpu/drm/vmwgfx/vmwgfx_cursor_plane.c
index c46f17ba7236..cb7c4d33c1b1 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_cursor_plane.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_cursor_plane.c
@@ -742,11 +742,17 @@ vmw_cursor_plane_atomic_update(struct drm_plane *plane,
 			       struct drm_atomic_state *state)
 {
 	struct vmw_bo *bo;
-	struct drm_plane_state *new_state =
-		drm_atomic_get_new_plane_state(state, plane);
-	struct drm_plane_state *old_state =
-		drm_atomic_get_old_plane_state(state, plane);
-	struct drm_crtc *crtc = new_state->crtc ?: old_state->crtc;
+	struct drm_plane_state *new_state;
+	struct drm_plane_state *old_state;
+
+	new_state = drm_atomic_get_new_plane_state(state, plane);
+	if (!new_state)
+		return;
+	old_state = drm_atomic_get_old_plane_state(state, plane);
+	struct drm_crtc *crtc = new_state->crtc ? new_state->crtc :
+		(old_state ? old_state->crtc : NULL);
+	if (!crtc)
+		return;
 	struct vmw_private *dev_priv = vmw_priv(plane->dev);
 	struct vmw_display_unit *du = vmw_crtc_to_du(crtc);
 	struct vmw_plane_state *vps = vmw_plane_state_to_vps(new_state);
-- 
2.54.0