[PATCH 3.18 45/57] drm: fix fb-helper vs MST dangling connector ptrs (v2)

Greg Kroah-Hartman
2015-02-03T23:44:17Z

From: Rob Clark <robdclark@gmail.com>

commit 2148f18fdb45f31ca269a7787fbc24053cd42e70 upstream.

VT switch back/forth from console to xserver (for example) has potential
to go horribly wrong if a dynamic DP MST connector ends up in the saved
modeset that is restored when switching back to fbcon.

When removing a dynamic connector, don't forget to clean up the saved
state.

v1: original
v2: null out set->fb if no more connectors to avoid making i915 cranky

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1184968
Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/drm_fb_helper.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)

--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -145,6 +145,31 @@ int drm_fb_helper_add_one_connector(stru
}
EXPORT_SYMBOL(drm_fb_helper_add_one_connector);

+static void remove_from_modeset(struct drm_mode_set *set,
+ struct drm_connector *connector)
+{
+ int i, j;
+
+ for (i = 0; i < set->num_connectors; i++) {
+ if (set->connectors[i] == connector)
+ break;
+ }
+
+ if (i == set->num_connectors)
+ return;
+
+ for (j = i + 1; j < set->num_connectors; j++) {
+ set->connectors[j - 1] = set->connectors[j];
+ }
+ set->num_connectors--;
+
+ /* because i915 is pissy about this..
+ * TODO maybe need to makes sure we set it back to !=NULL somewhere?
+ */
+ if (set->num_connectors == 0)
+ set->fb = NULL;
+}
+
int drm_fb_helper_remove_one_connector(struct drm_fb_helper *fb_helper,
struct drm_connector *connector)
{
@@ -167,6 +192,11 @@ int drm_fb_helper_remove_one_connector(s
}
fb_helper->connector_count--;
kfree(fb_helper_connector);
+
+ /* also cleanup dangling references to the connector: */
+ for (i = 0; i < fb_helper->crtc_count; i++)
+ remove_from_modeset(&fb_helper->crtc_info[i].mode_set, connector);
+
return 0;
}
EXPORT_SYMBOL(drm_fb_helper_remove_one_connector);