[PATCH 1/2] drm/ttm: Check ttm_debugfs_root before creating files under it

[Ma, Jun]

On 1/13/2023 5:37 PM, Christian König wrote:
> Am 13.01.23 um 06:34 schrieb Ma Jun:
>> Check the ttm_debugfs_root before creating files under it.
>> If the ttm_debugfs_root is NULL, all the files created for
>> ttm/ will be placed in the /sys/kerne/debug/ but not
>> /sys/kernel/debug/ttm/
> 
> Well NAK for upstreaming. Why should ttm_debugfs_root be NULL here?
> 

In my case, when the ttm/ removal fails during amdgpu uninstall and then
we try to modprobe the amdgpu again, the ttm_debugfs_root will be NULL
because the ttm/ already exists.

Regards,
Ma Jun

> Regards,
> Christian.
> 
>>
>> Signed-off-by: Ma Jun <Jun.Ma2 at amd.com>
>> ---
>>   drivers/gpu/drm/ttm/ttm_device.c |  3 ++-
>>   drivers/gpu/drm/ttm/ttm_pool.c   | 10 ++++++----
>>   drivers/gpu/drm/ttm/ttm_tt.c     |  5 +++--
>>   3 files changed, 11 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c
>> index e7147e304637..967bc2244df3 100644
>> --- a/drivers/gpu/drm/ttm/ttm_device.c
>> +++ b/drivers/gpu/drm/ttm/ttm_device.c
>> @@ -105,7 +105,8 @@ static int ttm_global_init(void)
>>   	INIT_LIST_HEAD(&glob->device_list);
>>   	atomic_set(&glob->bo_count, 0);
>>   
>> -	debugfs_create_atomic_t("buffer_objects", 0444, ttm_debugfs_root,
>> +	if(ttm_debugfs_root)
>> +		debugfs_create_atomic_t("buffer_objects", 0444, ttm_debugfs_root,
>>   				&glob->bo_count);
>>   out:
>>   	if (ret && ttm_debugfs_root)
>> diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c
>> index 21b61631f73a..d95a65f759df 100644
>> --- a/drivers/gpu/drm/ttm/ttm_pool.c
>> +++ b/drivers/gpu/drm/ttm/ttm_pool.c
>> @@ -713,10 +713,12 @@ int ttm_pool_mgr_init(unsigned long num_pages)
>>   	}
>>   
>>   #ifdef CONFIG_DEBUG_FS
>> -	debugfs_create_file("page_pool", 0444, ttm_debugfs_root, NULL,
>> -			    &ttm_pool_debugfs_globals_fops);
>> -	debugfs_create_file("page_pool_shrink", 0400, ttm_debugfs_root, NULL,
>> -			    &ttm_pool_debugfs_shrink_fops);
>> +	if(ttm_debugfs_root) {
>> +		debugfs_create_file("page_pool", 0444, ttm_debugfs_root, NULL,
>> +				    &ttm_pool_debugfs_globals_fops);
>> +		debugfs_create_file("page_pool_shrink", 0400, ttm_debugfs_root, NULL,
>> +				    &ttm_pool_debugfs_shrink_fops);
>> +	}
>>   #endif
>>   
>>   	mm_shrinker.count_objects = ttm_pool_shrinker_count;
>> diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
>> index d505603930a7..fec443494ef0 100644
>> --- a/drivers/gpu/drm/ttm/ttm_tt.c
>> +++ b/drivers/gpu/drm/ttm/ttm_tt.c
>> @@ -394,8 +394,9 @@ DEFINE_SHOW_ATTRIBUTE(ttm_tt_debugfs_shrink);
>>   void ttm_tt_mgr_init(unsigned long num_pages, unsigned long num_dma32_pages)
>>   {
>>   #ifdef CONFIG_DEBUG_FS
>> -	debugfs_create_file("tt_shrink", 0400, ttm_debugfs_root, NULL,
>> -			    &ttm_tt_debugfs_shrink_fops);
>> +	if(ttm_debugfs_root)
>> +		debugfs_create_file("tt_shrink", 0400, ttm_debugfs_root, NULL,
>> +				    &ttm_tt_debugfs_shrink_fops);
>>   #endif
>>   
>>   	if (!ttm_pages_limit)
>