[LTP] [PATCH] pidns32: fix PID namespace nesting depth off-by-one

[Petr Vorel]

Hi Vasileios,

> The 2023 refactor used tst_atomic_inc() before clone with a zero-initial
> counter, which only performed 31 CLONE_NEWPID nests while still expecting
> MAXNEST (32). Compare the level to MAXNEST first, then increment and clone,
> so the shared counter runs 0..32 and the chain reaches 32 nested namespaces
> again.

Indeed, good catch.
Reviewed-by: Petr Vorel <pvorel@suse.cz>

Kind regards,
Petr

> Fixes: 647cfd468c3b ("Refactor pidns32 test using new LTP API")
> Signed-off-by: Vasileios Almpanis <vasileios.almpanis@virtuozzo.com>
> ---
>  testcases/kernel/containers/pidns/pidns32.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

> diff --git a/testcases/kernel/containers/pidns/pidns32.c b/testcases/kernel/containers/pidns/pidns32.c
> index fc9bf0aaa..3a272f569 100644
> --- a/testcases/kernel/containers/pidns/pidns32.c
> +++ b/testcases/kernel/containers/pidns/pidns32.c
> @@ -27,9 +27,11 @@ static pid_t child_func(void)
>  {
>  	pid_t cpid = 0;

> -	if (tst_atomic_inc(level) == MAXNEST)
> +	if (tst_atomic_load(level) == MAXNEST)
>  		return cpid;

> +	tst_atomic_inc(level);
> +
>  	cpid = SAFE_CLONE(&args);
>  	if (!cpid) {
>  		child_func();