[PATCH v3 0/2] selftests: sched: Add default target support for sched

[PATCH v3 0/2] selftests: sched: Add default target support for sched

[Sinadin Shan]

This patch series introduces changes to add default build support for
the sched tests in selftests.

The only test under sched is cs_prctl_test which validates cookies when
core scheduling is in effect. This test fails on systems where core
scheduling is disabled. The patch series also modifies this behaviour to
gracefully skip the test on such systems.

A system with core scheduling disabled would skip the test like:
~# ./run_kselftest.sh
TAP version 13
1..1
 timeout set to 45
 selftests: sched: cs_prctl_test
 prctl failed: Invalid argument
 Core sched not supported, hence skipping tests
ok 1 selftests: sched: cs_prctl_test # SKIP

Signed-off-by: Sinadin Shan <sinadin.shan@oracle.com>
---
v3:
* Use prctl to check core sched support instead of config
* v2 link: https://lore.kernel.org/all/20250221115750.631990-1-sinadin.shan@oracle.com/
v2:
* Add patch to skip cs_prctl_test on core scheduling disabled systems
* v1 link: https://lore.kernel.org/all/20250219064658.449069-1-sinadin.shan@oracle.com
---

Sinadin Shan (2):
  selftests: sched: add sched as a default selftest target
  selftests: sched: skip cs_prctl_test for systems with core scheduling
    disabled

 tools/testing/selftests/Makefile              |  1 +
 tools/testing/selftests/sched/cs_prctl_test.c | 34 ++++++++++++++++++-
 2 files changed, 34 insertions(+), 1 deletion(-)

-- 
2.43.5

[PATCH v3 1/2] selftests: sched: add sched as a default selftest target

[Sinadin Shan]

The sched tests are missing a target entry and hence out-of-tree build
support.

For instance:
make -C tools/testing/selftests install INSTALL_PATH=/foo/bar

is expected to build the sched tests and place them at /foo/bar.
But this is not observed since a TARGET entry is not present for sched.

This was suggested by Shuah in this conversation
Link: https://lore.kernel.org/linux-kselftest/60dd0240-8e45-4958-acf2-7eeee917785b@linuxfoundation.org/

Add support for sched selftests by adding sched as a default TARGET

Signed-off-by: Sinadin Shan <sinadin.shan@oracle.com>
---
 tools/testing/selftests/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 8daac70c2f9d2..e2d0d389ad912 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -91,6 +91,7 @@ TARGETS += rlimits
 TARGETS += rseq
 TARGETS += rtc
 TARGETS += rust
+TARGETS += sched
 TARGETS += sched_ext
 TARGETS += seccomp
 TARGETS += sgx
-- 
2.43.5

[PATCH v3 2/2] selftests: sched: skip cs_prctl_test for systems with core scheduling disabled

[Sinadin Shan]

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 because core scheduling isn't supported.

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 | 34 ++++++++++++++++++-
 1 file changed, 33 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..5b0047b50e640 100644
--- a/tools/testing/selftests/sched/cs_prctl_test.c
+++ b/tools/testing/selftests/sched/cs_prctl_test.c
@@ -109,6 +109,36 @@ static void handle_usage(int rc, char *msg)
 	exit(rc);
 }
 
+static void check_core_sched(void)
+{
+	unsigned long long cookie;
+	int ret, num_max_process;
+	char buffer[32];
+
+	FILE *fp = fopen("/proc/sys/kernel/pid_max", "r");
+
+	if (fp == NULL) {
+		perror("Failed to obtain max process number");
+		exit(EXIT_FAILURE);
+	}
+
+	if (fgets(buffer, sizeof(buffer), fp) == NULL) {
+		fclose(fp);
+		exit(EXIT_FAILURE);
+	}
+
+	num_max_process = atoi(buffer);
+	fclose(fp);
+
+	ret = prctl(PR_SCHED_CORE, PR_SCHED_CORE_GET, num_max_process+1, PIDTYPE_PID,
+			(unsigned long)&cookie);
+	if (ret == -1 && errno != ESRCH) {
+		perror("prctl failed");
+		printf("Core sched not supported, hence skipping tests\n");
+		exit(4);
+	}
+}
+
 static unsigned long get_cs_cookie(int pid)
 {
 	unsigned long long cookie;
@@ -117,7 +147,7 @@ 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 +300,8 @@ int main(int argc, char *argv[])
 	if (keypress)
 		delay = -1;
 
+	check_core_sched();
+
 	srand(time(NULL));
 
 	/* put into separate process group */
-- 
2.43.5

Re: [PATCH v3 2/2] selftests: sched: skip cs_prctl_test for systems with core scheduling disabled

[Shrikanth Hegde]

On 2/26/25 01:39, Sinadin Shan wrote:
> 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 because core scheduling isn't supported.
> 
> 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 | 34 ++++++++++++++++++-
>   1 file changed, 33 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..5b0047b50e640 100644
> --- a/tools/testing/selftests/sched/cs_prctl_test.c
> +++ b/tools/testing/selftests/sched/cs_prctl_test.c
> @@ -109,6 +109,36 @@ static void handle_usage(int rc, char *msg)
>   	exit(rc);
>   }
>   
> +static void check_core_sched(void)
> +{
> +	unsigned long long cookie;
> +	int ret, num_max_process;
> +	char buffer[32];
> +
> +	FILE *fp = fopen("/proc/sys/kernel/pid_max", "r");
> +
> +	if (fp == NULL) {
> +		perror("Failed to obtain max process number");
> +		exit(EXIT_FAILURE);
> +	}
> +
> +	if (fgets(buffer, sizeof(buffer), fp) == NULL) {
> +		fclose(fp);
> +		exit(EXIT_FAILURE);
> +	}
> +
> +	num_max_process = atoi(buffer);
> +	fclose(fp);
> +
> +	ret = prctl(PR_SCHED_CORE, PR_SCHED_CORE_GET, num_max_process+1, PIDTYPE_PID,
> +			(unsigned long)&cookie);
> +	if (ret == -1 && errno != ESRCH) {
> +		perror("prctl failed");
> +		printf("Core sched not supported, hence skipping tests\n");
> +		exit(4);
> +	}
> +}
> +
>   static unsigned long get_cs_cookie(int pid)
>   {
>   	unsigned long long cookie;
> @@ -117,7 +147,7 @@ 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 +300,8 @@ int main(int argc, char *argv[])
>   	if (keypress)
>   		delay = -1;
>   
> +	check_core_sched();
> +
>   	srand(time(NULL));
>   
>   	/* put into separate process group */


This works for me in my workflow. I don't know full selftest framework 
or how to trigger it.

When CONFIG_SCHED_CORE=n
-----------------------------
./cs_prctl_test
prctl failed: Invalid argument
Core sched not supported, hence skipping tests


When CONFIG_SCHED_CORE=y
-----------------------------
./cs_prctl_test
(369) PASSED: _prctl(PR_SCHED_CORE, PR_SCHED_CORE_MAX, 0, PIDTYPE_PGID, 
0) < 0 && errno == EINVAL
-1 = prctl(62, 2, 0, 2, 1)
(372) PASSED: _prctl(PR_SCHED_CORE, PR_SCHED_CORE_SHARE_TO, 0, 
PIDTYPE_PGID, 1) < 0 && errno == EINVAL
SUCCESS !!!


So for this patch,
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>

Re: [PATCH v3 2/2] selftests: sched: skip cs_prctl_test for systems with core scheduling disabled

[Chris Hyser]

On 2/26/25 01:39, Sinadin Shan wrote:
> 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 because core scheduling isn't supported.
> 
> 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 | 34 ++++++++++++++++++-
>  1 file changed, 33 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..5b0047b50e640 100644
> --- a/tools/testing/selftests/sched/cs_prctl_test.c
> +++ b/tools/testing/selftests/sched/cs_prctl_test.c
> @@ -109,6 +109,36 @@ static void handle_usage(int rc, char *msg)
>          exit(rc);
>  }
>  
> +static void check_core_sched(void)
> +{
> +       unsigned long long cookie;
> +       int ret, num_max_process;
> +       char buffer[32];
> +
> +       FILE *fp = fopen("/proc/sys/kernel/pid_max", "r");
> +
> +       if (fp == NULL) {
> +               perror("Failed to obtain max process number");
> +               exit(EXIT_FAILURE);
> +       }
> +
> +       if (fgets(buffer, sizeof(buffer), fp) == NULL) {
> +               fclose(fp);
> +               exit(EXIT_FAILURE);
> +       }
> +
> +       num_max_process = atoi(buffer);
> +       fclose(fp);
> +
> +       ret = prctl(PR_SCHED_CORE, PR_SCHED_CORE_GET, num_max_process+1, PIDTYPE_PID,
> +                       (unsigned long)&cookie);
> +       if (ret == -1 && errno != ESRCH) {
> +               perror("prctl failed");
> +               printf("Core sched not supported, hence skipping tests\n");
> +               exit(4);
> +       }
> +}
> +
>  static unsigned long get_cs_cookie(int pid)
>  {
>          unsigned long long cookie;
> @@ -117,7 +147,7 @@ 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 +300,8 @@ int main(int argc, char *argv[])
>          if (keypress)
>                  delay = -1;
>  
> +       check_core_sched();
> +
>          srand(time(NULL));
>  
>          /* put into separate process group */
> --
> 2.43.5

So assuming a return code of 4 means skip (and I believe you stated that affirmatively before), then this
should solve the problem. Thanks for fixing this.

Reviewed-by: Chris Hyser <chris.hyser@oracle.com>

-chrish