linux-kernel - Re: [PATCH v3 4/5] selftests/resctrl: Add resource_info_file

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Date: Fri, 26 Jan 2024 13:08:52 -0800
From: Reinette Chatre <reinette.chatre@...el.com>
To: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>,
	<shuah@...nel.org>, <fenghua.yu@...el.com>
CC: <linux-kernel@...r.kernel.org>, <linux-kselftest@...r.kernel.org>,
	<ilpo.jarvinen@...ux.intel.com>
Subject: Re: [PATCH v3 4/5] selftests/resctrl: Add resource_info_file_exists()

Hi Maciej,

On 1/25/2024 3:12 AM, Maciej Wieczor-Retman wrote:
> Feature checking done by resctrl_mon_feature_exists() covers features
> represented by the feature name presence inside the 'mon_features' file
> in /sys/fs/resctrl/info/L3_MON directory. There exists a different way
> to represent feature support and that is by the presence of 0 or 1 in a
> single file in the info/resource directory. In this case the filename
> represents what feature support is being indicated.
> 
> Add a generic function to check file presence in the
> /sys/fs/resctrl/info/<RESOURCE> directory.
> 
> Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
> ---
> Changelog v3:
> - Split off the new function into this patch. (Reinette)
> 
> Changelog v2:
> - Add this patch.
> 
>  tools/testing/selftests/resctrl/resctrl.h   |  2 ++
>  tools/testing/selftests/resctrl/resctrlfs.c | 26 +++++++++++++++++++++
>  2 files changed, 28 insertions(+)
> 
> diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
> index 4603b215b97e..c39105f46da9 100644
> --- a/tools/testing/selftests/resctrl/resctrl.h
> +++ b/tools/testing/selftests/resctrl/resctrl.h
> @@ -138,6 +138,8 @@ int umount_resctrlfs(void);
>  int validate_bw_report_request(char *bw_report);
>  bool resctrl_resource_exists(const char *resource);
>  bool resctrl_mon_feature_exists(const char *feature);
> +bool resource_info_file_exists(const char *resource,
> +			       const char *feature);

In addition what Ilpo commented about other line, this too can be
on one line.

>  bool test_resource_feature_check(const struct resctrl_test *test);
>  char *fgrep(FILE *inf, const char *str);
>  int taskset_benchmark(pid_t bm_pid, int cpu_no, cpu_set_t *old_affinity);
> diff --git a/tools/testing/selftests/resctrl/resctrlfs.c b/tools/testing/selftests/resctrl/resctrlfs.c
> index e4ba8614fb7b..a6427732e0ad 100644
> --- a/tools/testing/selftests/resctrl/resctrlfs.c
> +++ b/tools/testing/selftests/resctrl/resctrlfs.c
> @@ -763,6 +763,32 @@ bool resctrl_mon_feature_exists(const char *feature)
>  	return !!res;
>  }
>  
> +/*
> + * resource_info_file_exists - Check if a file is present inside
> + * /sys/fs/resctrl/info/RESOURCE.

As confirmed in the changelog this is intended to be a generic function that
tests if a file exists ...

> + * @resource:	Required resource (Eg: MB, L3, L2, etc.)
> + * @feature:	Required feature.

.. so assuming a use of this by referring to the file as "feature" is unexpected.

This function jumps between "file" and "feature" in comments and code, please
just stick to goal of making it a generic utility that checks for a file and
refer to it consistently so.

Reinette