netdev - Re: [PATCH v2] lib/string-choice: add yesno(), onoff(), enableddisabled(), plural() helpers

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Message-ID: <8e697984-03b5-44f3-304e-42d303724eaa@rasmusvillemoes.dk>
Date:   Mon, 30 Sep 2019 16:31:02 +0200
From:   Rasmus Villemoes <linux@...musvillemoes.dk>
To:     Jani Nikula <jani.nikula@...el.com>, linux-kernel@...r.kernel.org
Cc:     Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        intel-gfx@...ts.freedesktop.org,
        Vishal Kulkarni <vishal@...lsio.com>, netdev@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Julia Lawall <julia.lawall@...6.fr>
Subject: Re: [PATCH v2] lib/string-choice: add yesno(), onoff(),
 enableddisabled(), plural() helpers

On 30/09/2019 16.18, Jani Nikula wrote:
> The kernel has plenty of ternary operators to choose between constant
> strings, such as condition ? "yes" : "no", as well as value == 1 ? "" :
> "s":
> 
> 
> ---
> 
> v2: add string-choice.[ch] to not clutter kernel.h and to actually save
> space on string constants.
> 
> +EXPORT_SYMBOL(enableddisabled);
> +
> +const char *plural(long v)
> +{
> +	return v == 1 ? "" : "s";
> +}
> +EXPORT_SYMBOL(plural);
> 

Say what? I'll bet you a beer that this is a net loss: You're adding
hundreds of bytes of export symbol overhead, plus forcing gcc to emit
actual calls at the call sites, with all the register saving/restoring
that implies.

Please just do this as static inlines. As I said, the linker is
perfectly capable of merging string literals across translation units
(but of course not between vmlinux and modules), so any built-in code
that uses those helpers (or open-codes them, doesn't matter) will
automatically share those literals.

Rasmus