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

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Message-ID: <dff6b112e225993b113ec04f3205d837352b8961.camel@sipsolutions.net>
Date:   Sun, 28 Nov 2021 18:05:06 +0100
From:   Johannes Berg <johannes@...solutions.net>
To:     Sergey Ryazanov <ryazanov.s.a@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     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, 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).

johannes