linux-kernel - Re: [PATCH net-next v3] wifi: ath9k: Remove error checking for debugfs_create

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Date:   Mon, 21 Aug 2023 15:39:34 +0300
From:   Kalle Valo <kvalo@...nel.org>
To:     Toke Høiland-Jørgensen <toke@...e.dk>
Cc:     Wang Ming <machel@...o.com>, linux-wireless@...r.kernel.org,
        linux-kernel@...r.kernel.org, opensource.kernel@...o.com
Subject: Re: [PATCH net-next v3] wifi: ath9k: Remove error checking for
 debugfs_create_dir()

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

> Wang Ming <machel@...o.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@...o.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