[PATCH v2 2/2] selftests: sched: skip cs_prctl_test for systems with core scheduling disabled

[Sinadin Shan <sinadin.shan@oracle.com>]

For kernels with CONFIG_SCHED_CORE=n, the sched selftest cs_prctl_test
fails with "Not a core sched system" error. Change this to gracefully
skip the test for systems with core scheduling disabled. Exiting early
would also ensure failures reported in obtaining cookie are valid
failures and not due to the config.

Skip cs_prctl_test for systems with CONFIG_SCHED_CORE=n

Signed-off-by: Sinadin Shan <sinadin.shan@oracle.com>
---
 tools/testing/selftests/sched/cs_prctl_test.c | 29 ++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/sched/cs_prctl_test.c b/tools/testing/selftests/sched/cs_prctl_test.c
index 52d97fae4dbd8..60fd657b56c84 100644
--- a/tools/testing/selftests/sched/cs_prctl_test.c
+++ b/tools/testing/selftests/sched/cs_prctl_test.c
@@ -23,6 +23,7 @@
 #include <sys/eventfd.h>
 #include <sys/wait.h>
 #include <sys/types.h>
+#include <sys/utsname.h>
 #include <sched.h>
 #include <sys/prctl.h>
 #include <unistd.h>
@@ -109,6 +110,30 @@ static void handle_usage(int rc, char *msg)
 	exit(rc);
 }
 
+static void check_core_sched_support(void)
+{
+	char config[128] = "/proc/config.gz";
+	char cmd[128];
+	struct utsname kernel;
+
+	printf("## Checking for CONFIG_SCHED_CORE support\n");
+
+	if (access(config, F_OK) != 0)
+		if (uname(&kernel) == 0)
+			snprintf(config, sizeof(config), "/boot/config-%s", kernel.release);
+
+	if (access(config, F_OK) != 0) {
+		printf("Cannot find kernel config in /proc or /boot\n");
+		exit(EXIT_FAILURE);
+	}
+
+	snprintf(cmd, sizeof(cmd), "zgrep CONFIG_SCHED_CORE=[ym] %s", config);
+	if (system(cmd)) {
+		printf("Core scheduling not enabled in kernel, hence skipping tests\n");
+		exit(4);
+	}
+}
+
 static unsigned long get_cs_cookie(int pid)
 {
 	unsigned long long cookie;
@@ -117,7 +142,7 @@ static unsigned long get_cs_cookie(int pid)
 	ret = prctl(PR_SCHED_CORE, PR_SCHED_CORE_GET, pid, PIDTYPE_PID,
 		    (unsigned long)&cookie);
 	if (ret) {
-		printf("Not a core sched system\n");
+		printf("Failed to get cookie\n");
 		return -1UL;
 	}
 
@@ -270,6 +295,8 @@ int main(int argc, char *argv[])
 	if (keypress)
 		delay = -1;
 
+	check_core_sched_support();
+
 	srand(time(NULL));
 
 	/* put into separate process group */
-- 
2.43.5