drm/nouveau: Keep malloc references to MST ports

Lyude · Lyude · commit 81640f01c2aa · 2019-01-10T20:38:25.000-05:00
Now that we finally have a sane way to keep port allocations around, use it to fix the potential unchecked ->port accesses that nouveau makes by making sure we keep the mst port allocated for as long as it's drm_connector is accessible. Additionally, now that we've guaranteed that mstc->port is allocated for as long as we keep mstc around we can remove the connector registration checks for codepaths which release payloads, allowing us to release payloads on active topologies properly. These registration checks were only required before in order to avoid situations where mstc->port could technically be pointing at freed memory. Signed-off-by: Lyude Paul <lyude@redhat.com> Reviewed-by: Ben Skeggs <bskeggs@redhat.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@redhat.com> Cc: Jerry Zuo <Jerry.Zuo@amd.com> Cc: Harry Wentland <harry.wentland@amd.com> Cc: Juston Li <juston.li@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190111005343.17443-15-lyude@redhat.com
diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -956,7 +956,11 @@ static void
 nv50_mstc_destroy(struct drm_connector *connector)
 {
 	struct nv50_mstc *mstc = nv50_mstc(connector);
+
 	drm_connector_cleanup(&mstc->connector);
+	if (mstc->port)
+		drm_dp_mst_put_port_malloc(mstc->port);
+
 	kfree(mstc);
 }
 
@@ -1004,6 +1008,7 @@ nv50_mstc_new(struct nv50_mstm *mstm, struct drm_dp_mst_port *port,
 	drm_object_attach_property(&mstc->connector.base, dev->mode_config.path_property, 0);
 	drm_object_attach_property(&mstc->connector.base, dev->mode_config.tile_property, 0);
 	drm_connector_set_path_property(&mstc->connector, path);
+	drm_dp_mst_get_port_malloc(port);
 	return 0;
 }
 
@@ -1069,6 +1074,7 @@ nv50_mstm_destroy_connector(struct drm_dp_mst_topology_mgr *mgr,
 	drm_fb_helper_remove_one_connector(&drm->fbcon->helper, &mstc->connector);
 
 	drm_modeset_lock(&drm->dev->mode_config.connection_mutex, NULL);
+	drm_dp_mst_put_port_malloc(mstc->port);
 	mstc->port = NULL;
 	drm_modeset_unlock(&drm->dev->mode_config.connection_mutex);
 
