Re: [PATCH] drm/amdgpu: don't add files at control minor debugfs directory

[Shawn Starr <shawn.starr-bJEeYj9oJeDQT0dZR+AlfA@public.gmane.org>]

On Tuesday, December 6, 2016 8:59:09 AM EST Christian König wrote:
> Am 06.12.2016 um 02:00 schrieb Michel Dänzer:
> > On 06/12/16 05:07 AM, Alex Deucher 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, amdgpu_debugfs_add_files() accesses
> >> ->control->debugfs_root though. This results in the following Oops:
> >> 
> >> [    9.627636] BUG: unable to handle kernel NULL pointer dereference at
> >> 0000000000000018 [    9.628274] IP: amdgpu_debugfs_add_files+0x8d/0x100
> >> [amdgpu]
> >> [    9.628867] PGD 2514c7067
> >> [    9.628876] PUD 2514c8067
> >> [    9.629448] PMD 0
> >> [    9.630026] Oops: 0000 [#1] PREEMPT SMP
> >> [...]
> >> [    9.639906] Call Trace:
> >> [    9.640538]  amdgpu_fence_driver_init+0x1e/0x40 [amdgpu]
> >> [    9.641186]  amdgpu_device_init+0xa6d/0x1410 [amdgpu]
> >> [    9.641900]  ? kmalloc_order_trace+0x2e/0x100
> >> [    9.642587]  amdgpu_driver_load_kms+0x5b/0x200 [amdgpu]
> >> [    9.643355]  drm_dev_register+0xa7/0xd0
> >> [    9.644016]  drm_get_pci_dev+0xde/0x1d0
> >> [    9.644659]  amdgpu_pci_probe+0xbe/0xf0 [amdgpu]
> >> [...]
> >> 
> >> Fix this by omitting the drm_debugfs_create_files() call for the
> >> control minor debugfs directory which is now non-existent anyway.
> >> 
> >> Port of Nicolai Stange's radeon patch to amdgpu.
> >> 
> >> bug: https://bugs.freedesktop.org/show_bug.cgi?id=98915
> > 
> > Not sure about the kernel, but in other projects the convention is
> > 
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98915
> > 
> >> Fixes: 8a357d10043c ("drm: Nerf DRM_CONTROL nodes")
> >> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
> > 
> > Regardless of the above,
> > 
> > Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
> 
> Reviewed-by: Christian König <christian.koenig@amd.com>.
> 

Worked fine, fixed the issue for me.

Tested-by: Shawn Starr <shawn.starr@rogers.com>

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