Re: [PATCH v2] ath11k: remove error checking for debugfs_create_file()

["Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>]

On 2024/10/28 22:30, Jeff Johnson wrote:
> On 10/28/2024 7:02 AM, Kalle Valo wrote:
>> Zhen Lei <thunder.leizhen@huawei.com> writes:
>>
>>> Driver ath11k can work fine even if the debugfs files fail to be created.
>>> Therefore, the return value check of debugfs_create_file() should be
>>> ignored, as it says.
>>>
>>> Suggested-by: Jeff Johnson <quic_jjohnson@quicinc.com>
>>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
>>
>> Are you just guessing or did you confirm on a real device that ath11k
>> spectral really works without debugfs?

Let's be honest, the only thing I know for sure is that debugfs_create_file()
returns an error code when it fails, not NULL. When I was locating a problem,
I found that a call to debugfs_create_file() did not process the return value
correctly. So I searched for other drivers, including ath11k. I'm not familiar
with ath11k. How to modify requires your help and decision.

> 
> The debugfs_create_file() documentation tells us:
>  * NOTE: it's expected that most callers should _ignore_ the errors returned
>  * by this function. Other debugfs functions handle the fact that the "dentry"
>  * passed to them could be an error and they don't crash in that case.
>  * Drivers should generally work fine even if debugfs fails to init anyway.
> 
> The caveat is that any driver functionality that relies upon debugfs obviously
> won't work if the underlying file isn't created. Hence the language that the
> driver "should generally work fine" since all functionality that isn't tied to
> debugfs will still be available.
> 
> Since the relayfs functionality that spectral scan uses is dependent upon
> debugfs, this functionality won't work if the debugfs operation fails. So the
> question is, if that fails, do you continue running the driver that generally
> works fine supporting all other wifi operations, or do you return an error,
> and as part of the error handling, not init the driver and hence have no wifi
> operation?

Maybe Kalle just pointed out that my description was incorrect.

Hi Kalle:
  Can you give me a clear instruction?
  1) Rollback to v1
     https://www.spinics.net/lists/linux-wireless/msg257219.html
  2) Update commit message, I think I can borrow the description above.

> 
> The one thing I didn't check is that although the documentation tells us that
> debugfs functions handle an "error" dentry, I didn't check if relayfs handles it.
> 
> /jeff
> 
> .
> 

-- 
Regards,
  Zhen Lei