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

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Message-ID: <c5f8d593-e667-4b39-936b-21c5d92f7016@oracle.com>
Date: Mon, 24 Feb 2025 17:40:03 +0530
From: Sinadin Shan <sinadin.shan@...cle.com>
To: Shrikanth Hegde <sshegde@...ux.ibm.com>, shuah@...nel.org
Cc: linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
        chris.hyser@...cle.com
Subject: Re: [PATCH v2 2/2] selftests: sched: skip cs_prctl_test for systems
 with core scheduling disabled



On 24-02-2025 01:49 pm, Shrikanth Hegde wrote:
> 
> 
> On 2/21/25 17:27, 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 due to the config.
>>
>> Skip cs_prctl_test for systems with CONFIG_SCHED_CORE=n
> 
> I tried this on kernel built with CONFIG_SCHED_CORE=y.
> I did make, make modules_install and make install and reboot.
> 
> ./cs_prctl_test
> ## Checking for CONFIG_SCHED_CORE support
> Cannot find kernel config in /proc or /boot
> 
> This happens because, make install wouldnt copy the .config to /boot/ 
> config-<kernel-release>.
> 
> If the self-tests are to be used in development flow, these checks may 
> not be sufficient.

Right, this particular case was overlooked. To handle this, the test 
could take a path to the custom config as an argument. I shall work on 
getting this fixed.

Regards,
Shan
> 
> Not sure if i have missed any steps in building process.
> 
> 
>>
>> Signed-off-by: Sinadin Shan <sinadin.shan@...cle.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 */
>