Re: [PATCH v4 2/5] selftests/resctrl: Add helpers for the non-contiguous test

[Reinette Chatre <reinette.chatre@intel.com>]

Hi Maciej,

The subject mentions "helpers" (plural) that may not be accurate
anymore.

On 2/5/2024 4:08 AM, Maciej Wieczor-Retman wrote:
> The CAT non-contiguous selftests have to read the file responsible for
> reporting support of non-contiguous CBMs in kernel (resctrl). Then the
> test compares if that information matches what is reported by CPUID
> output.
> 
> Add a generic helper function to read an unsigned number from a file in
> /sys/fs/resctrl/info/<RESOURCE>/<FILE>.

The "a file in" above can be dropped or it should read "from a file in
/sys/fs/resctrl/info/<RESOURCE>".

> 
> Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
> ---
> Changelog v4:
> - Rewrite function comment.
> - Redo ksft_perror() as ksft_print_msg(). (Reinette)
> 
> Changelog v3:
> - Rewrite patch message.
> - Add documentation and rewrote the function. (Reinette)
> 
> Changelog v2:
> - Add this patch.
> 
>  tools/testing/selftests/resctrl/resctrl.h   |  1 +
>  tools/testing/selftests/resctrl/resctrlfs.c | 36 +++++++++++++++++++++
>  2 files changed, 37 insertions(+)
> 
> diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
> index a1462029998e..5116ea082d03 100644
> --- a/tools/testing/selftests/resctrl/resctrl.h
> +++ b/tools/testing/selftests/resctrl/resctrl.h
> @@ -162,6 +162,7 @@ unsigned int count_contiguous_bits(unsigned long val, unsigned int *start);
>  int get_full_cbm(const char *cache_type, unsigned long *mask);
>  int get_mask_no_shareable(const char *cache_type, unsigned long *mask);
>  int get_cache_size(int cpu_no, const char *cache_type, unsigned long *cache_size);
> +int resource_info_unsigned_get(const char *resource, const char *filename, unsigned int *val);
>  void ctrlc_handler(int signum, siginfo_t *info, void *ptr);
>  int signal_handler_register(void);
>  void signal_handler_unregister(void);
> diff --git a/tools/testing/selftests/resctrl/resctrlfs.c b/tools/testing/selftests/resctrl/resctrlfs.c
> index 5750662cce57..e0fbc46a917a 100644
> --- a/tools/testing/selftests/resctrl/resctrlfs.c
> +++ b/tools/testing/selftests/resctrl/resctrlfs.c
> @@ -249,6 +249,42 @@ static int get_bit_mask(const char *filename, unsigned long *mask)
>  	return 0;
>  }
>  
> +/**

Apologies for not being clear in my previous comment. I do not
think we want to start exposing resctrl selftest comments to the
kernel-doc tool using this change. The tests are using kernel-doc
style but this is done outside from the kernel-doc tool's view.

> + * resource_info_unsigned_get - Read an unsigned value from
> + * /sys/fs/resctrl/info/RESOURCE/FILENAME
> + * @resource:	Resource name that matches directory name in
> + *		/sys/fs/resctrl/info
> + * @filename:	File in /sys/fs/resctrl/info/@resource
> + * @val:	Contains read value on success.
> + *
> + * Return: = 0 on success, < 0 on failure. On success the read
> + * value is saved into the @val.

It can just be "saved into @val"

> + */
> +int resource_info_unsigned_get(const char *resource, const char *filename,
> +			       unsigned int *val)
> +{
> +	char file_path[PATH_MAX];
> +	FILE *fp;
> +
> +	snprintf(file_path, sizeof(file_path), "%s/%s/%s", INFO_PATH, resource,
> +		 filename);
> +
> +	fp = fopen(file_path, "r");
> +	if (!fp) {
> +		ksft_print_msg("Error in opening %s\n: %m\n", file_path);
> +		return -1;
> +	}

Apart from Ilpo's comment this can also just be "Error opening %s: ..."

> +
> +	if (fscanf(fp, "%u", val) <= 0) {
> +		ksft_print_msg("Could not get contents of %s\n: %m\n", file_path);
> +		fclose(fp);
> +		return -1;
> +	}
> +
> +	fclose(fp);
> +	return 0;
> +}
> +
>  /*
>   * create_bit_mask- Create bit mask from start, len pair
>   * @start:	LSB of the mask


Reinette