linux-kernel - Re: [PATCH] leds: trigger: ledtrig-cpu:: Fix a warning when compiling with W=1

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Date:   Thu, 28 Sep 2023 14:09:58 +0100
From:   Lee Jones <lee@...nel.org>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     Pavel Machek <pavel@....cz>, Bryan Wu <bryan.wu@...onical.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Jamie Iles <jamie@...ieiles.com>, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org, linux-leds@...r.kernel.org
Subject: Re: [PATCH] leds: trigger: ledtrig-cpu:: Fix a warning when
 compiling with W=1

On Sat, 23 Sep 2023, Christophe JAILLET wrote:

> In order to teach the compiler that 'trig->name' will never be truncated,
> we need to tell it that 'cpu' is not negative.
> 
> When building with W=1, this fixes the following warnings:
> 
>   drivers/leds/trigger/ledtrig-cpu.c: In function ‘ledtrig_cpu_init’:
>   drivers/leds/trigger/ledtrig-cpu.c:155:56: error: ‘%d’ directive output may be truncated writing between 1 and 11 bytes into a region of size 5 [-Werror=format-truncation=]
>     155 |                 snprintf(trig->name, MAX_NAME_LEN, "cpu%d", cpu);
>         |                                                        ^~
>   drivers/leds/trigger/ledtrig-cpu.c:155:52: note: directive argument in the range [-2147483648, 7]
>     155 |                 snprintf(trig->name, MAX_NAME_LEN, "cpu%d", cpu);
>         |                                                    ^~~~~~~
>   drivers/leds/trigger/ledtrig-cpu.c:155:17: note: ‘snprintf’ output between 5 and 15 bytes into a destination of size 8
>     155 |                 snprintf(trig->name, MAX_NAME_LEN, "cpu%d", cpu);
>         |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Fixes: 8f88731d052d ("led-triggers: create a trigger for CPU activity")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
>  drivers/leds/trigger/ledtrig-cpu.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

I made the subject line less generic and applied it, thanks.

-- 
Lee Jones [李琼斯]