drm/nouveau/bl: Fix oops on driver unbind
commit76f2e2bc627f7d08360ac731b6277d744d4eb599
authorLukas Wunner <lukas@wunner.de>
Sat, 17 Feb 2018 12:40:23 +0000 (17 13:40 +0100)
committerBen Skeggs <bskeggs@redhat.com>
Fri, 16 Mar 2018 01:55:05 +0000 (16 11:55 +1000)
tree3913d6ee560c0e4949434fb7ac905a2ddeefaecf
parentda5e45e619b3f101420c38b3006a9ae4f3ad19b0
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: b53ac1ee12a3 ("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>
drivers/gpu/drm/nouveau/nouveau_backlight.c