[PATCH 13/22] selftests/resctrl: Refactor get_cbm_mask()

[Ilpo Järvinen]

Callers of get_cbm_mask() are required to pass a string into which
the CBM bit mask is read into. Neither CAT nor CMT tests need the
mask as string but just convert it into an unsigned long value.

The bit mask reader can only read .../cbm_mask files.

Generalize the bit mask reading function into get_bit_mask() such that
it can be used to handle other files besides the .../cmb_mask and
handle the unsigned long conversion within within get_bit_mask() using
fscanf(). Alter get_cbm_mask() to construct the filename for
get_bit_mask().

Co-developed-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
---
 tools/testing/selftests/resctrl/cat_test.c  |  5 +--
 tools/testing/selftests/resctrl/cmt_test.c  |  5 +--
 tools/testing/selftests/resctrl/resctrl.h   |  2 +-
 tools/testing/selftests/resctrl/resctrlfs.c | 50 +++++++++++++++------
 4 files changed, 40 insertions(+), 22 deletions(-)

diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
index 90cbf86a0153..7fa693e4de8f 100644
--- a/tools/testing/selftests/resctrl/cat_test.c
+++ b/tools/testing/selftests/resctrl/cat_test.c
@@ -18,7 +18,6 @@
 #define MAX_DIFF		1000000
 
 static int count_of_bits;
-static char cbm_mask[256];
 static unsigned long long_mask;
 static unsigned long cache_size;
 
@@ -106,12 +105,10 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
 		return ret;
 
 	/* Get default cbm mask for L3/L2 cache */
-	ret = get_cbm_mask(cache_type, cbm_mask);
+	ret = get_cbm_mask(cache_type, &long_mask);
 	if (ret)
 		return ret;
 
-	long_mask = strtoul(cbm_mask, NULL, 16);
-
 	/* Get L3/L2 cache size */
 	ret = get_cache_size(cpu_no, cache_type, &cache_size);
 	if (ret)
diff --git a/tools/testing/selftests/resctrl/cmt_test.c b/tools/testing/selftests/resctrl/cmt_test.c
index 39fb869d57e6..5026d9863c6f 100644
--- a/tools/testing/selftests/resctrl/cmt_test.c
+++ b/tools/testing/selftests/resctrl/cmt_test.c
@@ -17,7 +17,6 @@
 #define MAX_DIFF_PERCENT	15
 
 static int count_of_bits;
-static char cbm_mask[256];
 static unsigned long long_mask;
 static unsigned long cache_size;
 
@@ -86,12 +85,10 @@ int cmt_resctrl_val(int cpu_no, int n, char **benchmark_cmd)
 	if (!validate_resctrl_feature_request(CMT_STR))
 		return -1;
 
-	ret = get_cbm_mask("L3", cbm_mask);
+	ret = get_cbm_mask("L3", &long_mask);
 	if (ret)
 		return ret;
 
-	long_mask = strtoul(cbm_mask, NULL, 16);
-
 	ret = get_cache_size(cpu_no, "L3", &cache_size);
 	if (ret)
 		return ret;
diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
index 594e72f04b63..6c23ceff2a04 100644
--- a/tools/testing/selftests/resctrl/resctrl.h
+++ b/tools/testing/selftests/resctrl/resctrl.h
@@ -108,7 +108,7 @@ void tests_cleanup(void);
 void mbm_test_cleanup(void);
 int mba_schemata_change(int cpu_no, char *bw_report, char **benchmark_cmd);
 void mba_test_cleanup(void);
-int get_cbm_mask(char *cache_type, char *cbm_mask);
+int get_cbm_mask(char *cache_type, unsigned long *mask);
 int get_cache_size(int cpu_no, char *cache_type, unsigned long *cache_size);
 void ctrlc_handler(int signum, siginfo_t *info, void *ptr);
 int cat_val(struct resctrl_val_param *param);
diff --git a/tools/testing/selftests/resctrl/resctrlfs.c b/tools/testing/selftests/resctrl/resctrlfs.c
index a63479f94a3e..6216955291e6 100644
--- a/tools/testing/selftests/resctrl/resctrlfs.c
+++ b/tools/testing/selftests/resctrl/resctrlfs.c
@@ -196,30 +196,29 @@ int get_cache_size(int cpu_no, char *cache_type, unsigned long *cache_size)
 #define CORE_SIBLINGS_PATH	"/sys/bus/cpu/devices/cpu"
 
 /*
- * get_cbm_mask - Get cbm mask for given cache
- * @cache_type:	Cache level L2/L3
- * @cbm_mask:	cbm_mask returned as a string
+ * get_bit_mask - Get bit mask from given file
+ * @filename:	File containing the mask
+ * @mask:	The bit mask returned as unsigned long
  *
  * Return: = 0 on success, < 0 on failure.
  */
-int get_cbm_mask(char *cache_type, char *cbm_mask)
+static int get_bit_mask(char *filename, unsigned long *mask)
 {
-	char cbm_mask_path[1024];
 	FILE *fp;
 
-	if (!cbm_mask)
+	if (!filename || !mask)
 		return -1;
 
-	sprintf(cbm_mask_path, "%s/%s/cbm_mask", INFO_PATH, cache_type);
-
-	fp = fopen(cbm_mask_path, "r");
+	fp = fopen(filename, "r");
 	if (!fp) {
-		perror("Failed to open cache level");
-
+		fprintf(stderr, "Failed to open bit mask file '%s': %s\n",
+			filename, strerror(errno));
 		return -1;
 	}
-	if (fscanf(fp, "%s", cbm_mask) <= 0) {
-		perror("Could not get max cbm_mask");
+
+	if (fscanf(fp, "%lx", mask) <= 0) {
+		fprintf(stderr, "Could not read bit mask file '%s': %s\n",
+			filename, strerror(errno));
 		fclose(fp);
 
 		return -1;
@@ -229,6 +228,31 @@ int get_cbm_mask(char *cache_type, char *cbm_mask)
 	return 0;
 }
 
+/*
+ * get_cbm_bits - Get number of bits in cbm mask
+ * @cache_type:		Cache level L2/L3
+ * @mask:		cbm_mask returned as unsigned long
+ *
+ * Return: = 0 on success, < 0 on failure.
+ */
+int get_cbm_mask(char *cache_type, unsigned long *mask)
+{
+	char cbm_mask_path[1024];
+	int ret;
+
+	if (!cache_type)
+		return -1;
+
+	snprintf(cbm_mask_path, sizeof(cbm_mask_path), "%s/%s/cbm_mask",
+		 INFO_PATH, cache_type);
+
+	ret = get_bit_mask(cbm_mask_path, mask);
+	if (ret)
+		return -1;
+
+	return 0;
+}
+
 /*
  * get_core_sibling - Get sibling core id from the same socket for given CPU
  * @cpu_no:	CPU number
-- 
2.30.2