On 7/10/2026 9:57 PM, Dan Carpenter wrote:
> On Fri, Jul 10, 2026 at 09:47:32PM +0800, Zhu, Lingshan wrote:
>> On 7/10/2026 7:29 PM, Srinivasan Shanmugam wrote:
>>
>>> debugfs is intended for debugging only, and failures to create debugfs
>>> entries should not affect normal operation.
>>>
>>> Remove the check for debugfs_create_dir() in kfd_debugfs_add_process().
>>> If debugfs entries cannot be created, continue without them instead of
>>> reporting an unnecessary error.
>>>
>>> Fixes: 22ab1bb3994a ("amdkfd: expose pasid of secondary contexts by
>>> debugfs")
>>> Reported-by: Dan Carpenter <[email protected]>
>>> Cc: Zhu Lingshan <[email protected]>
>>> Cc: Felix Kuehling <[email protected]>
>>> Signed-off-by: Srinivasan Shanmugam <[email protected]>
>>> ---
>>> drivers/gpu/drm/amd/amdkfd/kfd_debugfs.c | 4 ----
>>> 1 file changed, 4 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_debugfs.c
>>> b/drivers/gpu/drm/amd/amdkfd/kfd_debugfs.c
>>> index 02673f01b448..7c5bc9c4559a 100644
>>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_debugfs.c
>>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_debugfs.c
>>> @@ -211,10 +211,6 @@ int kfd_debugfs_add_process(struct kfd_process *p)
>>> entry->proc_dentry = debugfs_create_dir(name,
>>>
>>> primary_entry->proc_dentry);
>>> }
>>> - if (IS_ERR_OR_NULL(entry->proc_dentry)) {
>>> - ret = entry->proc_dentry ? PTR_ERR(entry->proc_dentry) :
>>> -ENOMEM;
>>> - goto err_free_entry;
>>> - }
>> We need this check because debugfs_create_dir() may fail.
>> Removing this check leads to entry leaking when fail.
>>
> Debugfs functions aren't supposed to be checked. Drivers aren't
> supposed to rely on debugfs so it's not required. If debugfs is
> failing then you are pretty much screwed anyway.
>
> I have a blog about the history of this:
> https://staticthinking.wordpress.com/2023/07/24/debugfs-functions-are-not-supposed-to-be-checked/
>
> This code is inside #if defined(CONFIG_DEBUG_FS) so the check
> isn't harmful except that it sets a bad example. Back in the day,
> this used to be a source of pain for me so Greg made it hard to
> write a correct check unless you have the #ifdef. It's to
> discourage checking.
Thanks Dan for the background, then how do we prevent the entry leaking if we
do not check debugfs_create_dir?
Thanks
Lingshan
>
> regards,
> dan carpenter
>
