selftests/resctrl: Fix incorrect parsing of iMC counters

iMC (Integrated Memory Controller) counters are usually at
"/sys/bus/event_source/devices/" and are named as "uncore_imc_<n>".
num_of_imcs() function tries to count number of such iMC counters so that
it could appropriately initialize required number of perf_attr structures
that could be used to read these iMC counters.

num_of_imcs() function assumes that all the directories under this path
that start with "uncore_imc" are iMC counters. But, on some systems there
could be directories named as "uncore_imc_free_running" which aren't iMC
counters. Trying to read from such directories will result in "not found
file" errors and MBM/MBA tests will fail.

Hence, fix the logic in num_of_imcs() such that it looks at the first
character after "uncore_imc_" to check if it's a numerical digit or not. If
it's a digit then the directory represents an iMC counter, else, skip the
directory.

Reported-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

diff --git a/tools/testing/selftests/resctrl/resctrl_val.c b/tools/testing/selftests/resctrl/resctrl_val.c
index 5dfae51..20d457c 100644 (file)
--- a/tools/testing/selftests/resctrl/resctrl_val.c
+++ b/tools/testing/selftests/resctrl/resctrl_val.c
@@ -221,8 +221,8 @@ static int read_from_imc_dir(char *imc_dir, int count)
  */
 static int num_of_imcs(void)
 {
+       char imc_dir[512], *temp;
        unsigned int count = 0;
-       char imc_dir[512];
        struct dirent *ep;
        int ret;
        DIR *dp;
@@ -230,7 +230,25 @@ static int num_of_imcs(void)
        dp = opendir(DYN_PMU_PATH);
        if (dp) {
                while ((ep = readdir(dp))) {
-                       if (strstr(ep->d_name, UNCORE_IMC)) {
+                       temp = strstr(ep->d_name, UNCORE_IMC);
+                       if (!temp)
+                               continue;
+
+                       /*
+                        * imc counters are named as "uncore_imc_<n>", hence
+                        * increment the pointer to point to <n>. Note that
+                        * sizeof(UNCORE_IMC) would count for null character as
+                        * well and hence the last underscore character in
+                        * uncore_imc'_' need not be counted.
+                        */
+                       temp = temp + sizeof(UNCORE_IMC);
+
+                       /*
+                        * Some directories under "DYN_PMU_PATH" could have
+                        * names like "uncore_imc_free_running", hence, check if
+                        * first character is a numerical digit or not.
+                        */
+                       if (temp[0] >= '0' && temp[0] <= '9') {
                                sprintf(imc_dir, "%s/%s/", DYN_PMU_PATH,
                                        ep->d_name);
                                ret = read_from_imc_dir(imc_dir, count);