[PATCH v4 3/5] selftests/resctrl: Split validate_resctrl_feature_request()

[Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>]

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.

Refactor validate_resctrl_feature_request() into two smaller functions
that each accomplish one check to give feature checking more
granularity:
- Resource directory presence in the /sys/fs/resctrl/info directory.
- Feature name presence in the /sys/fs/resctrl/info/L3_MON/mon_features
  file.

Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
---
Changelog v4:
- Roll back to using test_resource_feature_check() for CMT and MBA.
  (Ilpo).

Changelog v3:
- Move new function to a separate patch. (Reinette)
- Rewrite resctrl_mon_feature_exists() only for L3_MON.

Changelog v2:
- Add this patch.

 tools/testing/selftests/resctrl/cmt_test.c  |  2 +-
 tools/testing/selftests/resctrl/mba_test.c  |  2 +-
 tools/testing/selftests/resctrl/mbm_test.c  |  6 ++--
 tools/testing/selftests/resctrl/resctrl.h   |  3 +-
 tools/testing/selftests/resctrl/resctrlfs.c | 33 +++++++++++++--------
 5 files changed, 28 insertions(+), 18 deletions(-)

diff --git a/tools/testing/selftests/resctrl/cmt_test.c b/tools/testing/selftests/resctrl/cmt_test.c
index dd5ca343c469..c1157917a814 100644
--- a/tools/testing/selftests/resctrl/cmt_test.c
+++ b/tools/testing/selftests/resctrl/cmt_test.c
@@ -170,7 +170,7 @@ 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");
+	       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..fa99a91c8ab7 100644
--- a/tools/testing/selftests/resctrl/mba_test.c
+++ b/tools/testing/selftests/resctrl/mba_test.c
@@ -171,7 +171,7 @@ 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");
+	       resctrl_mon_feature_exists("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..9c885bc427ca 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("mbm_total_bytes") &&
+	       resctrl_mon_feature_exists("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 5116ea082d03..4603b215b97e 100644
--- a/tools/testing/selftests/resctrl/resctrl.h
+++ b/tools/testing/selftests/resctrl/resctrl.h
@@ -136,7 +136,8 @@ 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 *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 e0fbc46a917a..0cfec8bb23fd 100644
--- a/tools/testing/selftests/resctrl/resctrlfs.c
+++ b/tools/testing/selftests/resctrl/resctrlfs.c
@@ -708,20 +708,16 @@ 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)
@@ -736,11 +732,24 @@ 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 monitoring L3_MON feature is valid.
+ * @feature:	Required monitor feature (in mon_features file).
+ *
+ * Return: True if the feature is supported, else false.
+ */
+bool resctrl_mon_feature_exists(const char *feature)
+{
+	char *res;
+	FILE *inf;
+
 	if (!feature)
-		return true;
+		return false;
 
-	snprintf(res_path, sizeof(res_path), "%s/%s/mon_features", INFO_PATH, resource);
-	inf = fopen(res_path, "r");
+	inf = fopen("/sys/fs/resctrl/info/L3_MON/mon_features", "r");
 	if (!inf)
 		return false;
 
@@ -753,7 +762,7 @@ bool validate_resctrl_feature_request(const char *resource, const char *feature)
 
 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)
-- 
2.43.0