linux-kernel - Re: [PATCH] powercap: Replace sprintf() with sysfs

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Message-ID: <CAJZ5v0jJw70jM-NqF9A30UsBcya0arZ6yMXZYhvATimZOhppLA@mail.gmail.com>
Date: Thu, 15 Jan 2026 21:13:00 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Sumeet Pawnikar <sumeet4linux@...il.com>
Cc: rafael@...nel.org, linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powercap: Replace sprintf() with sysfs_emit() in sysfs
 show functions

On Sun, Jan 11, 2026 at 3:12 PM Sumeet Pawnikar <sumeet4linux@...il.com> wrote:
>
> Replace all sprintf() calls with sysfs_emit() in sysfs show functions.
> sysfs_emit() is preferred over sprintf() for formatting sysfs output
> as it provides better bounds checking and prevents potential buffer
> overflows.
> Also, replace sprintf() with sysfs_emit() in show_constraint_name()
> and simplify the code by removing the redundant strlen() call since
> sysfs_emit() returns the length.
>
> Signed-off-by: Sumeet Pawnikar <sumeet4linux@...il.com>
> ---
>  drivers/powercap/powercap_sys.c | 13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/powercap/powercap_sys.c b/drivers/powercap/powercap_sys.c
> index 1ff369880beb..f3b2ae635305 100644
> --- a/drivers/powercap/powercap_sys.c
> +++ b/drivers/powercap/powercap_sys.c
> @@ -27,7 +27,7 @@ static ssize_t _attr##_show(struct device *dev, \
>         \
>         if (power_zone->ops->get_##_attr) { \
>                 if (!power_zone->ops->get_##_attr(power_zone, &value)) \
> -                       len = sprintf(buf, "%lld\n", value); \
> +                       len = sysfs_emit(buf, "%lld\n", value); \
>         } \
>         \
>         return len; \
> @@ -75,7 +75,7 @@ static ssize_t show_constraint_##_attr(struct device *dev, \
>         pconst = &power_zone->constraints[id]; \
>         if (pconst && pconst->ops && pconst->ops->get_##_attr) { \
>                 if (!pconst->ops->get_##_attr(power_zone, id, &value)) \
> -                       len = sprintf(buf, "%lld\n", value); \
> +                       len = sysfs_emit(buf, "%lld\n", value); \
>         } \
>         \
>         return len; \
> @@ -171,9 +171,8 @@ static ssize_t show_constraint_name(struct device *dev,
>         if (pconst && pconst->ops && pconst->ops->get_name) {
>                 name = pconst->ops->get_name(power_zone, id);
>                 if (name) {
> -                       sprintf(buf, "%.*s\n", POWERCAP_CONSTRAINT_NAME_LEN - 1,
> -                               name);
> -                       len = strlen(buf);
> +                       len = sysfs_emit(buf, "%.*s\n",
> +                                        POWERCAP_CONSTRAINT_NAME_LEN - 1, name);
>                 }
>         }
>
> @@ -350,7 +349,7 @@ static ssize_t name_show(struct device *dev,
>  {
>         struct powercap_zone *power_zone = to_powercap_zone(dev);
>
> -       return sprintf(buf, "%s\n", power_zone->name);
> +       return sysfs_emit(buf, "%s\n", power_zone->name);
>  }
>
>  static DEVICE_ATTR_RO(name);
> @@ -438,7 +437,7 @@ static ssize_t enabled_show(struct device *dev,
>                                 mode = false;
>         }
>
> -       return sprintf(buf, "%d\n", mode);
> +       return sysfs_emit(buf, "%d\n", mode);
>  }
>
>  static ssize_t enabled_store(struct device *dev,
> --

Applied as 6.20 material, thanks!