[LTP] [PATCH] ipc/msgstress03: Assume all forks will run concurently

[Cyril Hrubis]

Hi!
> It appears that msgstress03 doesn't account for all PIDs that its children
> can use, as it expects the tasks will terminate quickly and not reach
> the PID limit.
> On some systems, this assumption can be invalid and the PID limit
> will be hit.
> Change the limit to account for all possible children at once, knowning
> that each child will fork as well.
> 
> Signed-off-by: Teo Couprie Diaz <teo.coupriediaz@arm.com>
> Reviewed-by: Richard Palethorpe <rpalethorpe@suse.com>
> ---
> This patch was already reviewed as part of a larger series[0]. The rest of
> the series needs a large rework to be merged, but I felt this patch was a
> simple and independnt enough to warrant a resend.
> No changes were made.
> 
> CI Build: https://github.com/Teo-CD/ltp/actions/runs/4502197808
> 
> [0]: https://lists.linux.it/pipermail/ltp/2023-February/033007.html
> 
>  testcases/kernel/syscalls/ipc/msgstress/msgstress03.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/testcases/kernel/syscalls/ipc/msgstress/msgstress03.c b/testcases/kernel/syscalls/ipc/msgstress/msgstress03.c
> index 3cb70ab18..0c46927b8 100644
> --- a/testcases/kernel/syscalls/ipc/msgstress/msgstress03.c
> +++ b/testcases/kernel/syscalls/ipc/msgstress/msgstress03.c
> @@ -109,7 +109,7 @@ int main(int argc, char **argv)
>  		}
>  	}
>  
> -	free_pids = tst_get_free_pids(cleanup);
> +	free_pids = tst_get_free_pids(cleanup) / 2;
>  	if (nprocs >= free_pids) {
>  		tst_resm(TINFO,
>  			 "Requested number of processes higher than limit (%d > %d), "

The logic behind the change is good, however I wonder if this would
produce a bit confusing message in case that we are over limit and
setting the value to the current maximum. Can we at least multiply the
values printed in the TINFO message by 2 so that we get real limits
instead of halves?

Generally the nprocs is actually the number of message queues, which is
confusing itself, but that is probably left for a bigger cleanup of the
testcase...

-- 
Cyril Hrubis
chrubis@suse.cz