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

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Message-ID: <e9c8a8c7-9a0d-09be-343d-038b7f791b98@linuxfoundation.org>
Date:   Thu, 7 Apr 2022 13:01:04 -0600
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     Athira Rajeev <atrajeev@...ux.vnet.ibm.com>, shuah@...nel.org,
        linux-kselftest@...r.kernel.org, disgoel@...ux.vnet.ibm.com
Cc:     acme@...nel.org, jolsa@...nel.org, mpe@...erman.id.au,
        linux-perf-users@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, maddy@...ux.vnet.ibm.com,
        kjain@...ux.ibm.com, srikar@...ux.vnet.ibm.com,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH V2] testing/selftests/mqueue: Fix mq_perf_tests to free
 the allocated cpu set

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)

>   	max_msgs = fopen(MAX_MSGS, "r+");
>   	max_msgsize = fopen(MAX_MSGSIZE, "r+");
> 

thanks,
-- Shuah