netdev - Re: [PATCH RESEND net-next 5/5] net: wwan: core: make debugfs optional

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Date:   Mon, 29 Nov 2021 01:57:07 +0300
From:   Sergey Ryazanov <ryazanov.s.a@...il.com>
To:     Johannes Berg <johannes@...solutions.net>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        M Chetan Kumar <m.chetan.kumar@...el.com>,
        Intel Corporation <linuxwwan@...el.com>,
        Loic Poulain <loic.poulain@...aro.org>
Subject: Re: [PATCH RESEND net-next 5/5] net: wwan: core: make debugfs optional

On Sun, Nov 28, 2021 at 8:05 PM Johannes Berg <johannes@...solutions.net> wrote:
> On Sun, 2021-11-28 at 15:55 +0300, Sergey Ryazanov wrote:
>> +#ifdef CONFIG_WWAN_DEBUGFS
>>  struct dentry *wwan_get_debugfs_dir(struct device *parent);
>> +#else
>> +static inline struct dentry *wwan_get_debugfs_dir(struct device *parent)
>> +{
>> +     return NULL;
>> +}
>> +#endif
>
> Now I have to send another email anyway ... but this one probably should
> be ERR_PTR(-ENODEV) or something, a la debugfs_create_dir() if debugfs
> is disabled, because then a trivial user of wwan's debugfs doesn't even
> have to care about whether it's enabled or not, it can just
> debugfs_create_dir() for its own and the debugfs core code will check
> and return immediately. Yes that's a bit more code space, but if you
> just have a debugfs file or two, having an extra Kconfig option is
> possibly overkill too. Especially if we get into this path because
> DEBUG_FS is disabled *entirely*, and thus all the functions will be
> empty inlines (but it might not be, so it should be consistent with
> debugfs always returning non-NULL).

Nice catch, thank you! Will rework in V2 to return ERR_PTR(-ENODEV).

-- 
Sergey