linux-kernel - Re: [PATCH] powercap: Adjust printing the constraint name with new line

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Date:   Tue, 10 Nov 2020 20:19:54 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Lukasz Luba <lukasz.luba@....com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Subject: Re: [PATCH] powercap: Adjust printing the constraint name with new line

On Mon, Nov 9, 2020 at 6:25 PM Lukasz Luba <lukasz.luba@....com> wrote:
>
> The constraint name has limit of size 30, which sometimes might be hit.
> When this happens the new line might be lost. Prevent this and set the
> new line when the name string is too long."
>
> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
> ---
>  drivers/powercap/powercap_sys.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/powercap/powercap_sys.c b/drivers/powercap/powercap_sys.c
> index f808c5fa9838..575f9fdb810e 100644
> --- a/drivers/powercap/powercap_sys.c
> +++ b/drivers/powercap/powercap_sys.c
> @@ -174,6 +174,10 @@ static ssize_t show_constraint_name(struct device *dev,
>                                                                 "%s\n", name);
>                         buf[POWERCAP_CONSTRAINT_NAME_LEN] = '\0';
>                         len = strlen(buf);
> +
> +                       /* When the 'name' is too long, don't lose new line */
> +                       if (strlen(name) >= POWERCAP_CONSTRAINT_NAME_LEN)
> +                               buf[POWERCAP_CONSTRAINT_NAME_LEN - 1] = '\n';

Wouldn't it be better to pass POWERCAP_CONSTRAINT_NAME_LEN - 1 to
snprintf() above?

>                 }
>         }
>
> --