Re: kill11: Skip with pipe-based core dump handlers

On Wed, Jul 08, 2026 at 03:26:34PM +0000, [email protected] wrote:
> Hi Jan,
>
> On Wed, 08 Jul 2026 15:37:26 +0200, Jan Polensky wrote:
> > kill11: Skip with pipe-based core dump handlers
>
> > +	SAFE_FILE_SCANF("/proc/sys/kernel/core_pattern", "%255s", core_pattern);
> > +	if (core_pattern[0] == '|') {
> > +		tst_brk(TCONF,
> > +			"Pipe-based core dumps detected (e.g., systemd-coredump). "
> > +			"Test requires direct filesystem core dumps. "
> > +			"Set kernel.core_pattern to a file path (e.g., /tmp/core.%%p) "
> > +			"or disable systemd-coredump for proper testing.");
> > +	}
>
> The check is in setup(), which aborts all iterations when it triggers.
> The hang described in the commit message can only occur when the child
> receives a signal that actually generates a core dump -- i.e. the cases
> with dumps_core == 1 (SIGQUIT, SIGILL, SIGABRT, SIGBUS, etc.).
>
> For the 12+ cases with dumps_core == 0 (SIGHUP, SIGKILL, SIGTERM,
> SIGPIPE, etc.) the child exits immediately without touching the core
> dump path, so SAFE_WAIT() returns right away and the pipe handler is
> never involved.
>
> Placing the skip in setup() discards over half the test coverage on any
> system running systemd-coredump, with no benefit for those cases.
>
> Would it work to keep the core_pattern detection in setup() (store the
> result in a static bool), then check it per-iteration in verify_kill()
> only when tc->dumps_core is set?
>
>   static bool pipe_based_coredump;
>
>   static void setup(void)
>   {
>       char core_pattern[256];
>       ...
>       SAFE_FILE_SCANF("/proc/sys/kernel/core_pattern",
>                       "%255s", core_pattern);
>       pipe_based_coredump = (core_pattern[0] == '|');
>   }
>
>   static void verify_kill(unsigned int n)
>   {
>       struct tcase *tc = &tcases[n];
>
>       if (tc->dumps_core && pipe_based_coredump) {
>           tst_res(TCONF, "%s: pipe-based core dump handler active",
>                   tst_strsig(tc->sig));
>           return;
>       }
>       ...
>   }
>
> That way the non-core-dumping signal cases still run.
>
> Verdict - Needs revision
>
> ---
> Note:
>
> The agent can sometimes produce false positives although often its
> findings are genuine. If you find issues with the review, please
> comment this email or ignore the suggestions.
>
> Regards,
> LTP AI Reviewer
Good point will send v2 soon.
Thank you!

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