On Mon, Dec 05, 2016 at 08:42:49AM +0100, Christian König wrote:
> Am 05.12.2016 um 08:27 schrieb Daniel Vetter:
> > On Sat, Dec 03, 2016 at 03:47:00PM +0100, Nicolai Stange wrote:
> > > Since commit 8a357d10043c ("drm: Nerf DRM_CONTROL nodes"), a
> > > struct drm_device's ->control member is always NULL.
> > >
> > > In the case of CONFIG_DEBUG_FS=y, radeon_debugfs_add_files() accesses
> > > ->control->debugfs_root though. This results in the following Oops:
> > >
> > > BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
> > > IP: radeon_debugfs_add_files+0x90/0x100 [radeon]
> > > PGD 0
> > > Oops: 0000 [#1] SMP
> > > [...]
> > > Call Trace:
> > > ? work_on_cpu+0xb0/0xb0
> > > radeon_fence_driver_init+0x120/0x150 [radeon]
> > > si_init+0x122/0xd50 [radeon]
> > > ? _raw_spin_unlock_irq+0x2c/0x40
> > > ? device_pm_check_callbacks+0xb3/0xc0
> > > radeon_device_init+0x958/0xda0 [radeon]
> > > radeon_driver_load_kms+0x9a/0x210 [radeon]
> > > drm_dev_register+0xa9/0xd0 [drm]
> > > drm_get_pci_dev+0x9c/0x1e0 [drm]
> > > radeon_pci_probe+0xb8/0xe0 [radeon]
> > > [...]
> > >
> > > Fix this by omitting the drm_debugfs_create_files() call for the
> > > control minor debugfs directory which is now non-existent anyway.
> > >
> > > Fixes: 8a357d10043c ("drm: Nerf DRM_CONTROL nodes")
> > > Signed-off-by: Nicolai Stange <nicstange@xxxxxxxxx>
> > Applied to drm-misc with Dave's irc ack, thanks for your patch.
>
> If it's still worth it the patch is Reviewed-by: Christian König
> <christian.koenig@xxxxxxx>.
>
> On the other hand when ->control is always NULL, why do we still have
> ->control anyway?
I'm chicken and didn't want to mass-delete code from the start. But yeah
after a few kernel releases to make sure no one noticed the removal of
control nodes we can garbage collected. I guess I've been bitten a few too
many times when trying to remove old stuff ;-)
> And BTW: Please double check the other drivers as well.
Yeah, I've done a full audit, only qxl turned up to have similar code.
Already merged with Dave's irc ack.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/dri-devel
