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Message-ID: <ZyJliZ3Uka8R5ilh@rhfedora>
Date: Wed, 30 Oct 2024 12:57:45 -0400
From: "John B. Wyatt IV" <jwyatt@...hat.com>
To: Vishnu Sanal T <t.v.s10123@...il.com>
Cc: linux-pm@...r.kernel.org, trenn@...e.com, shuah@...nel.org,
jkacur@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] implement set_enabled functions on powercap.c
On Wed, Oct 30, 2024 at 08:57:07PM +0530, Vishnu Sanal T wrote:
> Implement the functions sysfs_set_enabled, powercap_set_enabled,
> and powercap_zone_set_enabled on powercap.c.
>
> Signed-off-by: Vishnu Sanal T <t.v.s10123@...il.com>
> ---
> Changes in v2:
>
> - simplify the implementation of sysfs_set_enabled using system()
> function.
Hello Vishnu,
Ty for sending a patch to implement this.
I got several warnings trying to compile your patch. Please resolve
them. I have not tested your code yet. How are you testing your code?
> ---
> tools/power/cpupower/lib/powercap.c | 31 +++++++++++++++++++++++------
> 1 file changed, 25 insertions(+), 6 deletions(-)
>
> diff --git a/tools/power/cpupower/lib/powercap.c b/tools/power/cpupower/lib/powercap.c
> index 94a0c69e55ef..a2c0c33b7729 100644
> --- a/tools/power/cpupower/lib/powercap.c
> +++ b/tools/power/cpupower/lib/powercap.c
> @@ -70,6 +70,17 @@ static int sysfs_get_enabled(char *path, int *mode)
> return ret;
> }
>
> +static int sysfs_set_enabled(char *path, int mode)
> +{
> + char command[SYSFS_PATH_MAX + 10];
> +
> + char yes_no = (char)(mode + '0');
What does yes or no mean for setting a value?
`is_set` or using something with the word 'mode' would be a better
variable name?
> +
> + sprintf(command, "echo -n %c > %s", yes_no, path);
> +
> + return system(command);
> +}
> +
In function ‘sysfs_set_enabled’,
inlined from ‘powercap_set_enabled’ at lib/powercap.c:95:9:
lib/powercap.c:79:9: note: ‘sprintf’ output between 13 and 267 bytes into a destination of size 265
79 | sprintf(command, "echo -n %c > %s", yes_no, path);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
lib/powercap.c: In function ‘powercap_zone_set_enabled’:
lib/powercap.c:79:40: warning: ‘%s’ directive writing up to 254 bytes into a region of size 253 [-Wformat-overflow=]
79 | sprintf(command, "echo -n %c > %s", yes_no, path);
| ^~
......
203 | return sysfs_set_enabled(path, mode);
| ~~~~
In function ‘sysfs_set_enabled’,
inlined from ‘powercap_zone_set_enabled’ at lib/powercap.c:203:9:
lib/powercap.c:79:9: note: ‘sprintf’ output between 13 and 267 bytes into a destination of size 265
79 | sprintf(command, "echo -n %c > %s", yes_no, path);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> int powercap_get_enabled(int *mode)
> {
> char path[SYSFS_PATH_MAX] = PATH_TO_POWERCAP "/intel-rapl/enabled";
> @@ -77,12 +88,11 @@ int powercap_get_enabled(int *mode)
> return sysfs_get_enabled(path, mode);
> }
>
> -/*
> - * TODO: implement function. Returns dummy 0 for now.
> - */
> int powercap_set_enabled(int mode)
> {
> - return 0;
> + char path[SYSFS_PATH_MAX] = PATH_TO_POWERCAP "/intel-rapl/enabled";
> +
> + return sysfs_set_enabled(path, mode);
> }
lib/powercap.c: In function ‘powercap_set_enabled’:
lib/powercap.c:79:40: warning: ‘%s’ directive writing up to 254 bytes into a region of size 253 [-Wformat-overflow=]
79 | sprintf(command, "echo -n %c > %s", yes_no, path);
| ^~
......
95 | return sysfs_set_enabled(path, mode);
>
> /*
> @@ -180,8 +190,17 @@ int powercap_zone_get_enabled(struct powercap_zone *zone, int *mode)
>
> int powercap_zone_set_enabled(struct powercap_zone *zone, int mode)
> {
> - /* To be done if needed */
> - return 0;
> + char path[SYSFS_PATH_MAX] = PATH_TO_POWERCAP;
> +
> + if ((strlen(PATH_TO_POWERCAP) + strlen(zone->sys_name)) +
> + strlen("/enabled") + 1 >= SYSFS_PATH_MAX)
> + return -1;
> +
> + strcat(path, "/");
> + strcat(path, zone->sys_name);
> + strcat(path, "/enabled");
> +
> + return sysfs_set_enabled(path, mode);
> }
>
>
> --
> 2.47.0
>
--
Sincerely,
John Wyatt
Software Engineer, Core Kernel
Red Hat
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