[PATCH net-next v3] wifi: ath9k: Remove error checking for debugfs_create_dir()

[PATCH net-next v3] wifi: ath9k: Remove error checking for debugfs_create_dir()

[Wang Ming]

It is expected that most callers should _ignore_ the errors
return by debugfs_create_dir() in ath9k_htc_init_debug().

Signed-off-by: Wang Ming <machel@vivo.com>
---
 drivers/net/wireless/ath/ath9k/htc_drv_debug.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_debug.c b/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
index b3ed65e5c4da..85ad45771b44 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
@@ -491,8 +491,6 @@ int ath9k_htc_init_debug(struct ath_hw *ah)
 
 	priv->debug.debugfs_phy = debugfs_create_dir(KBUILD_MODNAME,
 					     priv->hw->wiphy->debugfsdir);
-	if (!priv->debug.debugfs_phy)
-		return -ENOMEM;
 
 	ath9k_cmn_spectral_init_debug(&priv->spec_priv, priv->debug.debugfs_phy);
 
-- 
2.25.1

Re: [PATCH net-next v3] wifi: ath9k: Remove error checking for debugfs_create_dir()

[Kalle Valo]

Wang Ming <machel@vivo.com> writes:

> It is expected that most callers should _ignore_ the errors
> return by debugfs_create_dir() in ath9k_htc_init_debug().
>
> Signed-off-by: Wang Ming <machel@vivo.com>

ath9k patches go to ath-next, not net-next. So do *not* put net-next
into Subject. No need to resend because of this.

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Re: [PATCH net-next v3] wifi: ath9k: Remove error checking for debugfs_create_dir()

[Toke Høiland-Jørgensen]

Wang Ming <machel@vivo.com> writes:

> It is expected that most callers should _ignore_ the errors
> return by debugfs_create_dir() in ath9k_htc_init_debug().
>
> Signed-off-by: Wang Ming <machel@vivo.com>
> ---
>  drivers/net/wireless/ath/ath9k/htc_drv_debug.c | 2 --
>  1 file changed, 2 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_debug.c b/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
> index b3ed65e5c4da..85ad45771b44 100644
> --- a/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
> +++ b/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
> @@ -491,8 +491,6 @@ int ath9k_htc_init_debug(struct ath_hw *ah)
>  
>  	priv->debug.debugfs_phy = debugfs_create_dir(KBUILD_MODNAME,
>  					     priv->hw->wiphy->debugfsdir);
> -	if (!priv->debug.debugfs_phy)
> -		return -ENOMEM;

Hmm, so it's true that all the debugfs_create* functions deal correctly
with the dir pointer being an error pointer, which means that it's
possible to just ignore the return value of debugfs_create_dir() without
anything breaking. However, it also seems kinda pointless to have all
those calls if we know they're going to fail, so I prefer v1 of this
patch that just fixed the IS_ERR check. No need to resend, we can just
apply v1 instead...

-Toke

Re: [PATCH net-next v3] wifi: ath9k: Remove error checking for debugfs_create_dir()

[Kalle Valo]

Toke Høiland-Jørgensen <toke@toke.dk> writes:

> Wang Ming <machel@vivo.com> writes:
>
>> It is expected that most callers should _ignore_ the errors
>> return by debugfs_create_dir() in ath9k_htc_init_debug().
>>
>> Signed-off-by: Wang Ming <machel@vivo.com>
>> ---
>>  drivers/net/wireless/ath/ath9k/htc_drv_debug.c | 2 --
>>  1 file changed, 2 deletions(-)
>>
>> diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_debug.c b/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
>> index b3ed65e5c4da..85ad45771b44 100644
>> --- a/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
>> +++ b/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
>> @@ -491,8 +491,6 @@ int ath9k_htc_init_debug(struct ath_hw *ah)
>>  
>>  	priv->debug.debugfs_phy = debugfs_create_dir(KBUILD_MODNAME,
>>  					     priv->hw->wiphy->debugfsdir);
>> -	if (!priv->debug.debugfs_phy)
>> -		return -ENOMEM;
>
> Hmm, so it's true that all the debugfs_create* functions deal correctly
> with the dir pointer being an error pointer, which means that it's
> possible to just ignore the return value of debugfs_create_dir() without
> anything breaking.

The comment in debugfs_create_dir() states:

 * 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.

> However, it also seems kinda pointless to have all those calls if we
> know they're going to fail, so I prefer v1 of this patch that just
> fixed the IS_ERR check. No need to resend, we can just apply v1
> instead...

Because of the comment I'm leaning towards v3.

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Re: [PATCH net-next v3] wifi: ath9k: Remove error checking for debugfs_create_dir()

[Toke Høiland-Jørgensen]

Kalle Valo <kvalo@kernel.org> writes:

> Toke Høiland-Jørgensen <toke@toke.dk> writes:
>
>> Wang Ming <machel@vivo.com> writes:
>>
>>> It is expected that most callers should _ignore_ the errors
>>> return by debugfs_create_dir() in ath9k_htc_init_debug().
>>>
>>> Signed-off-by: Wang Ming <machel@vivo.com>
>>> ---
>>>  drivers/net/wireless/ath/ath9k/htc_drv_debug.c | 2 --
>>>  1 file changed, 2 deletions(-)
>>>
>>> diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_debug.c b/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
>>> index b3ed65e5c4da..85ad45771b44 100644
>>> --- a/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
>>> +++ b/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
>>> @@ -491,8 +491,6 @@ int ath9k_htc_init_debug(struct ath_hw *ah)
>>>  
>>>  	priv->debug.debugfs_phy = debugfs_create_dir(KBUILD_MODNAME,
>>>  					     priv->hw->wiphy->debugfsdir);
>>> -	if (!priv->debug.debugfs_phy)
>>> -		return -ENOMEM;
>>
>> Hmm, so it's true that all the debugfs_create* functions deal correctly
>> with the dir pointer being an error pointer, which means that it's
>> possible to just ignore the return value of debugfs_create_dir() without
>> anything breaking.
>
> The comment in debugfs_create_dir() states:
>
>  * 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.
>
>> However, it also seems kinda pointless to have all those calls if we
>> know they're going to fail, so I prefer v1 of this patch that just
>> fixed the IS_ERR check. No need to resend, we can just apply v1
>> instead...
>
> Because of the comment I'm leaning towards v3.

Well, the comment says "most callers" :)

I think having an early return like this is perfectly valid
optimisation, even if it doesn't really make any performance difference.
I don't feel incredibly strongly about it (given that the current check
is broken I guess the early return has never actually worked), so if you
feel like overriding your submaintainer on this, feel free ;)

-Toke

Re: [PATCH net-next v3] wifi: ath9k: Remove error checking for debugfs_create_dir()

[Kalle Valo]

Toke Høiland-Jørgensen <toke@toke.dk> writes:

> Kalle Valo <kvalo@kernel.org> writes:
>
>> Toke Høiland-Jørgensen <toke@toke.dk> writes:
>>
>>> Wang Ming <machel@vivo.com> writes:
>>>
>>>> It is expected that most callers should _ignore_ the errors
>>>> return by debugfs_create_dir() in ath9k_htc_init_debug().
>>>>
>>>> Signed-off-by: Wang Ming <machel@vivo.com>
>>>> ---
>>>>  drivers/net/wireless/ath/ath9k/htc_drv_debug.c | 2 --
>>>>  1 file changed, 2 deletions(-)
>>>>
>>>> diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_debug.c b/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
>>>> index b3ed65e5c4da..85ad45771b44 100644
>>>> --- a/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
>>>> +++ b/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
>>>> @@ -491,8 +491,6 @@ int ath9k_htc_init_debug(struct ath_hw *ah)
>>>>  
>>>>  	priv->debug.debugfs_phy = debugfs_create_dir(KBUILD_MODNAME,
>>>>  					     priv->hw->wiphy->debugfsdir);
>>>> -	if (!priv->debug.debugfs_phy)
>>>> -		return -ENOMEM;
>>>
>>> Hmm, so it's true that all the debugfs_create* functions deal correctly
>>> with the dir pointer being an error pointer, which means that it's
>>> possible to just ignore the return value of debugfs_create_dir() without
>>> anything breaking.
>>
>> The comment in debugfs_create_dir() states:
>>
>>  * 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.
>>
>>> However, it also seems kinda pointless to have all those calls if we
>>> know they're going to fail, so I prefer v1 of this patch that just
>>> fixed the IS_ERR check. No need to resend, we can just apply v1
>>> instead...
>>
>> Because of the comment I'm leaning towards v3.
>
> Well, the comment says "most callers" :)
>
> I think having an early return like this is perfectly valid
> optimisation, even if it doesn't really make any performance difference.
> I don't feel incredibly strongly about it (given that the current check
> is broken I guess the early return has never actually worked), so if you
> feel like overriding your submaintainer on this, feel free ;)

No no, I don't want to override anything :) Just making sure you were
aware of the comment. v1 is in my pending branch right now.

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Re: [PATCH net-next v3] wifi: ath9k: Remove error checking for debugfs_create_dir()

[Toke Høiland-Jørgensen]

Kalle Valo <kvalo@kernel.org> writes:

> Toke Høiland-Jørgensen <toke@toke.dk> writes:
>
>> Kalle Valo <kvalo@kernel.org> writes:
>>
>>> Toke Høiland-Jørgensen <toke@toke.dk> writes:
>>>
>>>> Wang Ming <machel@vivo.com> writes:
>>>>
>>>>> It is expected that most callers should _ignore_ the errors
>>>>> return by debugfs_create_dir() in ath9k_htc_init_debug().
>>>>>
>>>>> Signed-off-by: Wang Ming <machel@vivo.com>
>>>>> ---
>>>>>  drivers/net/wireless/ath/ath9k/htc_drv_debug.c | 2 --
>>>>>  1 file changed, 2 deletions(-)
>>>>>
>>>>> diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_debug.c b/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
>>>>> index b3ed65e5c4da..85ad45771b44 100644
>>>>> --- a/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
>>>>> +++ b/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
>>>>> @@ -491,8 +491,6 @@ int ath9k_htc_init_debug(struct ath_hw *ah)
>>>>>  
>>>>>  	priv->debug.debugfs_phy = debugfs_create_dir(KBUILD_MODNAME,
>>>>>  					     priv->hw->wiphy->debugfsdir);
>>>>> -	if (!priv->debug.debugfs_phy)
>>>>> -		return -ENOMEM;
>>>>
>>>> Hmm, so it's true that all the debugfs_create* functions deal correctly
>>>> with the dir pointer being an error pointer, which means that it's
>>>> possible to just ignore the return value of debugfs_create_dir() without
>>>> anything breaking.
>>>
>>> The comment in debugfs_create_dir() states:
>>>
>>>  * 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.
>>>
>>>> However, it also seems kinda pointless to have all those calls if we
>>>> know they're going to fail, so I prefer v1 of this patch that just
>>>> fixed the IS_ERR check. No need to resend, we can just apply v1
>>>> instead...
>>>
>>> Because of the comment I'm leaning towards v3.
>>
>> Well, the comment says "most callers" :)
>>
>> I think having an early return like this is perfectly valid
>> optimisation, even if it doesn't really make any performance difference.
>> I don't feel incredibly strongly about it (given that the current check
>> is broken I guess the early return has never actually worked), so if you
>> feel like overriding your submaintainer on this, feel free ;)
>
> No no, I don't want to override anything :) Just making sure you were
> aware of the comment. v1 is in my pending branch right now.

Alright, cool :)

-Toke