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

[Alex Deucher]

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
Fixes: 8a357d10043c ("drm: Nerf DRM_CONTROL nodes")
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 4701d94..a578540 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -2512,9 +2512,6 @@ int amdgpu_debugfs_add_files(struct amdgpu_device *adev,
 	adev->debugfs_count = i;
 #if defined(CONFIG_DEBUG_FS)
 	drm_debugfs_create_files(files, nfiles,
-				 adev->ddev->control->debugfs_root,
-				 adev->ddev->control);
-	drm_debugfs_create_files(files, nfiles,
 				 adev->ddev->primary->debugfs_root,
 				 adev->ddev->primary);
 #endif
@@ -2529,9 +2526,6 @@ static void amdgpu_debugfs_remove_files(struct amdgpu_device *adev)
 	for (i = 0; i < adev->debugfs_count; i++) {
 		drm_debugfs_remove_files(adev->debugfs[i].files,
 					 adev->debugfs[i].num_files,
-					 adev->ddev->control);
-		drm_debugfs_remove_files(adev->debugfs[i].files,
-					 adev->debugfs[i].num_files,
 					 adev->ddev->primary);
 	}
 #endif
-- 
2.5.5