[PATCH] drm/amdgpu: no need to clean debugfs at amdgpu

[Christian König]

If we do this we should probably make nails with heads and remove the 
whole cleanup/fini code as well.

Christian.

Am 27.02.20 um 12:50 schrieb Yintian Tao:
> drm_minor_unregister will invoke drm_debugfs_cleanup
> to clean all the child node under primary minor node.
> We don't need to invoke amdgpu_debugfs_fini and
> amdgpu_debugfs_regs_cleanup to clean agian.
> Otherwise, it will raise the NULL pointer like below.
> [   45.046029] BUG: unable to handle kernel NULL pointer dereference at 00000000000000a8
> [   45.047256] PGD 0 P4D 0
> [   45.047713] Oops: 0002 [#1] SMP PTI
> [   45.048198] CPU: 0 PID: 2796 Comm: modprobe Tainted: G        W  OE     4.18.0-15-generic #16~18.04.1-Ubuntu
> [   45.049538] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
> [   45.050651] RIP: 0010:down_write+0x1f/0x40
> [   45.051194] Code: 90 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 53 48 89 fb e8 ce d9 ff ff 48 ba 01 00 00 00 ff ff ff ff 48 89 d8 <f0> 48 0f c1 10 85 d2 74 05 e8 53 1c ff ff 65 48 8b 04 25 00 5c 01
> [   45.053702] RSP: 0018:ffffad8f4133fd40 EFLAGS: 00010246
> [   45.054384] RAX: 00000000000000a8 RBX: 00000000000000a8 RCX: ffffa011327dd814
> [   45.055349] RDX: ffffffff00000001 RSI: 0000000000000001 RDI: 00000000000000a8
> [   45.056346] RBP: ffffad8f4133fd48 R08: 0000000000000000 R09: ffffffffc0690a00
> [   45.057326] R10: ffffad8f4133fd58 R11: 0000000000000001 R12: ffffa0113cff0300
> [   45.058266] R13: ffffa0113c0a0000 R14: ffffffffc0c02a10 R15: ffffa0113e5c7860
> [   45.059221] FS:  00007f60d46f9540(0000) GS:ffffa0113fc00000(0000) knlGS:0000000000000000
> [   45.060809] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   45.061826] CR2: 00000000000000a8 CR3: 0000000136250004 CR4: 00000000003606f0
> [   45.062913] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [   45.064404] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [   45.065897] Call Trace:
> [   45.066426]  debugfs_remove+0x36/0xa0
> [   45.067131]  amdgpu_debugfs_ring_fini+0x15/0x20 [amdgpu]
> [   45.068019]  amdgpu_debugfs_fini+0x2c/0x50 [amdgpu]
> [   45.068756]  amdgpu_pci_remove+0x49/0x70 [amdgpu]
> [   45.069439]  pci_device_remove+0x3e/0xc0
> [   45.070037]  device_release_driver_internal+0x18a/0x260
> [   45.070842]  driver_detach+0x3f/0x80
> [   45.071325]  bus_remove_driver+0x59/0xd0
> [   45.071850]  driver_unregister+0x2c/0x40
> [   45.072377]  pci_unregister_driver+0x22/0xa0
> [   45.073043]  amdgpu_exit+0x15/0x57c [amdgpu]
> [   45.073683]  __x64_sys_delete_module+0x146/0x280
> [   45.074369]  do_syscall_64+0x5a/0x120
> [   45.074916]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> Signed-off-by: Yintian Tao <yttao at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 1 -
>   drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c    | 1 -
>   2 files changed, 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 8ef8a49b9255..351096ab4301 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -3237,7 +3237,6 @@ void amdgpu_device_fini(struct amdgpu_device *adev)
>   	adev->rmmio = NULL;
>   	amdgpu_device_doorbell_fini(adev);
>   
> -	amdgpu_debugfs_regs_cleanup(adev);
>   	device_remove_file(adev->dev, &dev_attr_pcie_replay_count);
>   	if (adev->ucode_sysfs_en)
>   		amdgpu_ucode_sysfs_fini(adev);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> index 7cf5f597b90a..02d80b9dbfe1 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> @@ -1139,7 +1139,6 @@ amdgpu_pci_remove(struct pci_dev *pdev)
>   		DRM_ERROR("Hotplug removal is not supported\n");
>   	drm_dev_unplug(dev);
>   	drm_dev_put(dev);
> -	amdgpu_debugfs_fini(adev);
>   	amdgpu_driver_unload_kms(dev);
>   	pci_disable_device(pdev);
>   	pci_set_drvdata(pdev, NULL);