4.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Lukas Wunner <lukas@xxxxxxxxx>
commit 76f2e2bc627f7d08360ac731b6277d744d4eb599 upstream.
Unbinding nouveau on a dual GPU MacBook Pro oopses because we iterate
over the bl_connectors list in nouveau_backlight_exit() but skipped
initializing it in nouveau_backlight_init(). Stacktrace for posterity:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
IP: nouveau_backlight_exit+0x2b/0x70 [nouveau]
nouveau_display_destroy+0x29/0x80 [nouveau]
nouveau_drm_unload+0x65/0xe0 [nouveau]
drm_dev_unregister+0x3c/0xe0 [drm]
drm_put_dev+0x2e/0x60 [drm]
nouveau_drm_device_remove+0x47/0x70 [nouveau]
pci_device_remove+0x36/0xb0
device_release_driver_internal+0x157/0x220
driver_detach+0x39/0x70
bus_remove_driver+0x51/0xd0
pci_unregister_driver+0x2a/0xa0
nouveau_drm_exit+0x15/0xfb0 [nouveau]
SyS_delete_module+0x18c/0x290
system_call_fast_compare_end+0xc/0x6f
Fixes: b53ac1ee12a3 ("drm/nouveau/bl: Do not register interface if Apple GMUX detected")
Cc: stable@xxxxxxxxxxxxxxx # v4.10+
Cc: Pierre Moreau <pierre.morrow@xxxxxxx>
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
Signed-off-by: Ben Skeggs <bskeggs@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/nouveau/nouveau_backlight.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
+++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
@@ -268,13 +268,13 @@ nouveau_backlight_init(struct drm_device
struct nvif_device *device = &drm->client.device;
struct drm_connector *connector;
+ INIT_LIST_HEAD(&drm->bl_connectors);
+
if (apple_gmux_present()) {
NV_INFO(drm, "Apple GMUX detected: not registering Nouveau backlight interface\n");
return 0;
}
- INIT_LIST_HEAD(&drm->bl_connectors);
-
list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
if (connector->connector_type != DRM_MODE_CONNECTOR_LVDS &&
connector->connector_type != DRM_MODE_CONNECTOR_eDP)