linux-kernel - Re: [PATCH V2] testing/selftests/mqueue: Fix mq_perf

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Date:   Fri, 8 Apr 2022 12:55:46 +0530
From:   Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
To:     Shuah Khan <skhan@...uxfoundation.org>
Cc:     shuah@...nel.org, linux-kselftest@...r.kernel.org,
        disgoel@...ux.vnet.ibm.com,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        linux-perf-users@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        maddy@...ux.vnet.ibm.com, kajoljain <kjain@...ux.ibm.com>,
        Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Subject: Re: [PATCH V2] testing/selftests/mqueue: Fix mq_perf_tests to free
 the allocated cpu set



> On 08-Apr-2022, at 12:31 AM, Shuah Khan <skhan@...uxfoundation.org> wrote:
> 
> On 4/7/22 12:40 PM, Athira Rajeev wrote:
>> The selftest "mqueue/mq_perf_tests.c" use CPU_ALLOC to allocate
>> CPU set. This cpu set is used further in pthread_attr_setaffinity_np
>> and by pthread_create in the code. But in current code, allocated
>> cpu set is not freed.
>> Fix this issue by adding CPU_FREE in the "shutdown" function which
>> is called in most of the error/exit path for the cleanup. Also add
>> CPU_FREE in some of the error paths where shutdown is not called.
>> Fixes: 7820b0715b6f ("tools/selftests: add mq_perf_tests")
>> Signed-off-by: Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
>> ---
>> Changelog:
>> From v1 -> v2:
>>  Addressed review comment from Shuah Khan to add
>>  CPU_FREE in other exit paths where it is needed
> 
> Thank you. I have a couple of comments on making the error
> paths simpler. Please see below.
> 
>>  tools/testing/selftests/mqueue/mq_perf_tests.c | 10 +++++++++-
>>  1 file changed, 9 insertions(+), 1 deletion(-)
>> diff --git a/tools/testing/selftests/mqueue/mq_perf_tests.c b/tools/testing/selftests/mqueue/mq_perf_tests.c
>> index b019e0b8221c..182434c7898d 100644
>> --- a/tools/testing/selftests/mqueue/mq_perf_tests.c
>> +++ b/tools/testing/selftests/mqueue/mq_perf_tests.c
>> @@ -180,6 +180,9 @@ void shutdown(int exit_val, char *err_cause, int line_no)
>>  	if (in_shutdown++)
>>  		return;
>>  +	/* Free the cpu_set allocated using CPU_ALLOC in main function */
>> +	CPU_FREE(cpu_set);
>> +
>>  	for (i = 0; i < num_cpus_to_pin; i++)
>>  		if (cpu_threads[i]) {
>>  			pthread_kill(cpu_threads[i], SIGUSR1);
>> @@ -589,6 +592,7 @@ int main(int argc, char *argv[])
>>  						cpu_set)) {
>>  					fprintf(stderr, "Any given CPU may "
>>  						"only be given once.\n");
>> +					CPU_FREE(cpu_set);
> 
> This could be done in a common error path handling.
> 
>>  					exit(1);
>>  				} else
>>  					CPU_SET_S(cpus_to_pin[cpu],
>> @@ -607,6 +611,7 @@ int main(int argc, char *argv[])
>>  				queue_path = malloc(strlen(option) + 2);
>>  				if (!queue_path) {
>>  					perror("malloc()");
>> +					CPU_FREE(cpu_set);
> 
> This could be done in a common error path handling.
> 
>>  					exit(1);
>>  				}
>>  				queue_path[0] = '/';
>> @@ -619,6 +624,7 @@ int main(int argc, char *argv[])
>>  	}
>>    	if (continuous_mode && num_cpus_to_pin == 0) {
>> +		CPU_FREE(cpu_set);
> 
> This could be done in a common error path handling.
> 
>>  		fprintf(stderr, "Must pass at least one CPU to continuous "
>>  			"mode.\n");
>>  		poptPrintUsage(popt_context, stderr, 0);
>> @@ -628,10 +634,12 @@ int main(int argc, char *argv[])
>>  		cpus_to_pin[0] = cpus_online - 1;
>>  	}
>>  -	if (getuid() != 0)
>> +	if (getuid() != 0) {
>> +		CPU_FREE(cpu_set);
>>  		ksft_exit_skip("Not running as root, but almost all tests "
>>  			"require root in order to modify\nsystem settings.  "
>>  			"Exiting.\n");
>> +	}
>>  
> 
> Why not move this check before CPU_ALLOC and make this the very first
> check in main()?
> 
> With this change the other places where CPU_FREE is added right before
> exit(1). Something like this:
> 
> err_code:
> 	CPU_FREE(cpu_set);
> 	exit(code)
Hi Shuah

Thanks for the comments. Addressed these in V3

Athira
> 
>>  	max_msgs = fopen(MAX_MSGS, "r+");
>>  	max_msgsize = fopen(MAX_MSGSIZE, "r+");
> 
> thanks,
> -- Shuah