drm: Reject mode set with current fb if no current fb is bound

When doing a mode set with the special fb id -1, reject the mode set if
no fb is currently bound to the crtc.

Also remove the pointless list traversal to find the current crtc based
on the current crtc :)

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 6 insertions, 8 deletions

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 6fdaf6fe94eb..bbcecdb4e0ad 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -1755,7 +1755,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
         struct drm_mode_config *config = &dev->mode_config;
         struct drm_mode_crtc *crtc_req = data;
         struct drm_mode_object *obj;
-        struct drm_crtc *crtc, *crtcfb;
+        struct drm_crtc *crtc;
         struct drm_connector **connector_set = NULL, *connector;
         struct drm_framebuffer *fb = NULL;
         struct drm_display_mode *mode = NULL;
@@ -1782,14 +1782,12 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
                 /* If we have a mode we need a framebuffer. */
                 /* If we pass -1, set the mode with the currently bound fb */
                 if (crtc_req->fb_id == -1) {
-                        list_for_each_entry(crtcfb,
-                                            &dev->mode_config.crtc_list, head) {
-                                if (crtcfb == crtc) {
-                                        DRM_DEBUG_KMS("Using current fb for "
-                                                        "setmode\n");
-                                        fb = crtc->fb;
-                                }
+                        if (!crtc->fb) {
+                                DRM_DEBUG_KMS("CRTC doesn't have current FB\n");
+                                ret = -EINVAL;
+                                goto out;
                         }
+                        fb = crtc->fb;
                 } else {
                         obj = drm_mode_object_find(dev, crtc_req->fb_id,
                                                    DRM_MODE_OBJECT_FB);