Re: [PATCH v2 3/4] selftests/resctrl: Split validate_resctrl_feature_request()

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

Hi Maciej,

On 12/12/2023 6:52 AM, Maciej Wieczor-Retman wrote:
> validate_resctrl_feature_request() is used to test both if a resource is
> present in the info directory, and if a passed monitoring feature is
> present in the mon_features file. There exists a different way to
> represent feature support and that is by the presence of 0 or 1 in
> single file in the info/resource directory. In this case the filename
> represents what feature support is being indicated.
> 
> Split validate_resctrl_feature_request() into three smaller functions
> that each accomplish one check:
> - Resource directory presence in the /sys/fs/resctrl/info directory.
> - Feature name presence in the /sys/fs/resctrl/info/RESOURCE/mon_features file.
> - Feature file presence in a given /sys/fs/resctrl/info/RESOURCE directory.

Please present refactoring of existing code and introduction of new
feature as separate patches. 

> 
> Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
> ---
> Changelog v2:
> - Added this patch.
> 
>  tools/testing/selftests/resctrl/cat_test.c  |  2 -
>  tools/testing/selftests/resctrl/cmt_test.c  |  4 +-
>  tools/testing/selftests/resctrl/mba_test.c  |  5 +-
>  tools/testing/selftests/resctrl/mbm_test.c  |  6 +--
>  tools/testing/selftests/resctrl/resctrl.h   |  6 ++-
>  tools/testing/selftests/resctrl/resctrlfs.c | 59 +++++++++++++++++----
>  6 files changed, 63 insertions(+), 19 deletions(-)
> 
> diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
> index 39fc9303b8e8..7dc7206b3b99 100644
> --- a/tools/testing/selftests/resctrl/cat_test.c
> +++ b/tools/testing/selftests/resctrl/cat_test.c
> @@ -1,9 +1,7 @@
>  // SPDX-License-Identifier: GPL-2.0
>  /*
>   * Cache Allocation Technology (CAT) test
> - *
>   * Copyright (C) 2018 Intel Corporation
> - *
>   * Authors:
>   *    Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>,
>   *    Fenghua Yu <fenghua.yu@intel.com>

Some unrelated changes here. 

> diff --git a/tools/testing/selftests/resctrl/cmt_test.c b/tools/testing/selftests/resctrl/cmt_test.c
> index dd5ca343c469..7b63aec8e2c4 100644
> --- a/tools/testing/selftests/resctrl/cmt_test.c
> +++ b/tools/testing/selftests/resctrl/cmt_test.c
> @@ -169,8 +169,8 @@ static int cmt_run_test(const struct resctrl_test *test, const struct user_param
>  
>  static bool cmt_feature_check(const struct resctrl_test *test)
>  {
> -	return test_resource_feature_check(test) &&
> -	       validate_resctrl_feature_request("L3_MON", "llc_occupancy");
> +	return resctrl_mon_feature_exists("L3_MON", "llc_occupancy") &&
> +	       resctrl_resource_exists("L3");
>  }
>  
>  struct resctrl_test cmt_test = {
> diff --git a/tools/testing/selftests/resctrl/mba_test.c b/tools/testing/selftests/resctrl/mba_test.c
> index da256d2dbe5c..ecf1c186448d 100644
> --- a/tools/testing/selftests/resctrl/mba_test.c
> +++ b/tools/testing/selftests/resctrl/mba_test.c
> @@ -170,8 +170,9 @@ static int mba_run_test(const struct resctrl_test *test, const struct user_param
>  
>  static bool mba_feature_check(const struct resctrl_test *test)
>  {
> -	return test_resource_feature_check(test) &&
> -	       validate_resctrl_feature_request("L3_MON", "mbm_local_bytes");
> +	return resctrl_resource_exists(test->resource) &&
> +	       resctrl_mon_feature_exists("L3_MON",
> +					  "mbm_local_bytes");
>  }
>  
>  struct resctrl_test mba_test = {
> diff --git a/tools/testing/selftests/resctrl/mbm_test.c b/tools/testing/selftests/resctrl/mbm_test.c
> index 34879e7b71a0..d67ffa3ec63a 100644
> --- a/tools/testing/selftests/resctrl/mbm_test.c
> +++ b/tools/testing/selftests/resctrl/mbm_test.c
> @@ -97,7 +97,7 @@ static int mbm_setup(const struct resctrl_test *test,
>  		return END_OF_TESTS;
>  
>  	/* Set up shemata with 100% allocation on the first run. */
> -	if (p->num_of_runs == 0 && validate_resctrl_feature_request("MB", NULL))
> +	if (p->num_of_runs == 0 && resctrl_resource_exists("MB"))
>  		ret = write_schemata(p->ctrlgrp, "100", uparams->cpu, test->resource);
>  
>  	p->num_of_runs++;
> @@ -140,8 +140,8 @@ static int mbm_run_test(const struct resctrl_test *test, const struct user_param
>  
>  static bool mbm_feature_check(const struct resctrl_test *test)
>  {
> -	return validate_resctrl_feature_request("L3_MON", "mbm_total_bytes") &&
> -	       validate_resctrl_feature_request("L3_MON", "mbm_local_bytes");
> +	return resctrl_mon_feature_exists("L3_MON", "mbm_total_bytes") &&
> +	       resctrl_mon_feature_exists("L3_MON", "mbm_local_bytes");
>  }
>  
>  struct resctrl_test mbm_test = {
> diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
> index 8f72d94b9cbe..74041a35d4ba 100644
> --- a/tools/testing/selftests/resctrl/resctrl.h
> +++ b/tools/testing/selftests/resctrl/resctrl.h
> @@ -135,7 +135,11 @@ int get_domain_id(const char *resource, int cpu_no, int *domain_id);
>  int mount_resctrlfs(void);
>  int umount_resctrlfs(void);
>  int validate_bw_report_request(char *bw_report);
> -bool validate_resctrl_feature_request(const char *resource, const char *feature);
> +bool resctrl_resource_exists(const char *resource);
> +bool resctrl_mon_feature_exists(const char *resource,
> +				const char *feature);
> +bool resctrl_cache_feature_exists(const char *resource,
> +				  const char *feature);
>  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 70333440ff2f..8546421f0940 100644
> --- a/tools/testing/selftests/resctrl/resctrlfs.c
> +++ b/tools/testing/selftests/resctrl/resctrlfs.c
> @@ -697,20 +697,16 @@ char *fgrep(FILE *inf, const char *str)
>  }
>  
>  /*
> - * validate_resctrl_feature_request - Check if requested feature is valid.
> - * @resource:	Required resource (e.g., MB, L3, L2, L3_MON, etc.)
> - * @feature:	Required monitor feature (in mon_features file). Can only be
> - *		set for L3_MON. Must be NULL for all other resources.
> + * resctrl_resource_exists - Check if a resource is supported.
> + * @resource:	Resctrl resource (e.g., MB, L3, L2, L3_MON, etc.)
>   *
> - * Return: True if the resource/feature is supported, else false. False is
> + * Return: True if the resource is supported, else false. False is
>   *         also returned if resctrl FS is not mounted.
>   */
> -bool validate_resctrl_feature_request(const char *resource, const char *feature)
> +bool resctrl_resource_exists(const char *resource)
>  {
>  	char res_path[PATH_MAX];
>  	struct stat statbuf;
> -	char *res;
> -	FILE *inf;
>  	int ret;
>  
>  	if (!resource)
> @@ -725,6 +721,25 @@ bool validate_resctrl_feature_request(const char *resource, const char *feature)
>  	if (stat(res_path, &statbuf))
>  		return false;
>  
> +	return true;
> +}
> +
> +/*
> + * resctrl_mon_feature_exists - Check if requested feature is valid.
> + * @resource:	Required resource (e.g., MB, L3, L2, L3_MON, etc.)

If this is intended for the monitoring resource and L3_MON (per below) is the
only valid resource then @resource cannot be all of the examples shown. Why is
the @resource argument needed?

> + * @feature:	Required monitor feature (in mon_features file). Can only be
> + *		set for L3_MON. Must be NULL for all other resources.

Which other resources?

> + *
> + * Return: True if the resource/feature is supported, else false. False is
> + *         also returned if resctrl FS is not mounted.
> + */
> +bool resctrl_mon_feature_exists(const char *resource,
> +				const char *feature)
> +{
> +	char res_path[PATH_MAX];
> +	char *res;
> +	FILE *inf;
> +
>  	if (!feature)
>  		return true;

Doesn't this mean that resctrl_mon_feature_exists(NULL, NULL) will return true? 

>  
> @@ -740,9 +755,35 @@ bool validate_resctrl_feature_request(const char *resource, const char *feature)
>  	return !!res;
>  }
>  
> +/*
> + * resctrl_cache_feature_exists - Check if a file that indicates a
> + * cache related feature support is present.

Seems like this is not really specific to a cache ... it can
check for any info file related to any resource.


> + * @resource:	Required cache resource (L3 or L2)
> + * @feature:	Required cache feature.

This seems to assume some usage of this utility. What if it
is, for example, resource_info_file_exists() or resource_info_file_readable()?

> + *
> + * Return: True if the feature is supported, else false.
> + */
> +bool resctrl_cache_feature_exists(const char *resource,
> +				  const char *feature)
> +{
> +	char res_path[PATH_MAX];
> +	struct stat statbuf;
> +
> +	if (!feature)
> +		return true;

resctrl_cache_feature_exists(NULL, NULL) will return true, no?


> +
> +	snprintf(res_path, sizeof(res_path), "%s/%s/%s", INFO_PATH, resource,
> +		 feature);
> +
> +	if (stat(res_path, &statbuf))
> +		return false;

I think it will be more robust to look at statbuf to learn if the file type
is correct and the file is actually readable.

> +
> +	return true;
> +}
> +
>  bool test_resource_feature_check(const struct resctrl_test *test)
>  {
> -	return validate_resctrl_feature_request(test->resource, NULL);
> +	return resctrl_resource_exists(test->resource);
>  }
>  
>  int filter_dmesg(void)

Reinette