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drm/nouveau/bl: Fix oops on driver unbind 

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: b53ac1ee12 ("drm/nouveau/bl: Do not register interface if Apple GMUX detected")
Cc: stable@vger.kernel.org # v4.10+
Cc: Pierre Moreau <pierre.morrow@free.fr>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
This commit is contained in:
Lukas Wunner 2018-02-17 13:40:23 +01:00 committed by Ben Skeggs
parent da5e45e619
commit 76f2e2bc62
1 changed files with 2 additions and 2 deletions
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4
drivers/gpu/drm/nouveau/nouveau_backlight.c
View File

@ -268,13 +268,13 @@ nouveau_backlight_init(struct drm_device *dev)
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)