[LTP] [PATCH] syscalls/setrlimit06: Add new test for RLIMIT_CPU

[Cyril Hrubis]

Hi!
> This is also a regression test for commit c3bca5d450b62 in kernel:
> "posix-cpu-timers: Ensure set_process_cpu_timer is always evaluated"
> 
> Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
> ---
>  runtest/syscalls                                  |   1 +
>  testcases/kernel/syscalls/setrlimit/.gitignore    |   1 +
>  testcases/kernel/syscalls/setrlimit/setrlimit06.c | 108 ++++++++++++++++++++++
>  3 files changed, 110 insertions(+)
>  create mode 100644 testcases/kernel/syscalls/setrlimit/setrlimit06.c
> 
> diff --git a/runtest/syscalls b/runtest/syscalls
> index 668c87c..2e36709 100644
> --- a/runtest/syscalls
> +++ b/runtest/syscalls
> @@ -1197,6 +1197,7 @@ setrlimit02 setrlimit02
>  setrlimit03 setrlimit03
>  setrlimit04 setrlimit04
>  setrlimit05 setrlimit05
> +setrlimit06 setrlimit06
>  
>  set_robust_list01 set_robust_list01
>  set_thread_area01 set_thread_area01
> diff --git a/testcases/kernel/syscalls/setrlimit/.gitignore b/testcases/kernel/syscalls/setrlimit/.gitignore
> index e91f7e8..a790eb9 100644
> --- a/testcases/kernel/syscalls/setrlimit/.gitignore
> +++ b/testcases/kernel/syscalls/setrlimit/.gitignore
> @@ -3,3 +3,4 @@
>  /setrlimit03
>  /setrlimit04
>  /setrlimit05
> +/setrlimit06
> diff --git a/testcases/kernel/syscalls/setrlimit/setrlimit06.c b/testcases/kernel/syscalls/setrlimit/setrlimit06.c
> new file mode 100644
> index 0000000..d6004a5
> --- /dev/null
> +++ b/testcases/kernel/syscalls/setrlimit/setrlimit06.c
> @@ -0,0 +1,108 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2019 FUJITSU LIMITED. All rights reserved.
> + * Author: Xiao Yang <yangx.jy@cn.fujitsu.com>
> + */
> +
> +/*
> + * Description:
> + * Set CPU time limit for a process and check its behavior
> + * when reaching CPU time limit.
> + * 1) Process received SIGXCPU signal when reaching soft limit
> + *    of CPU time.
> + * 2) Process received SIGKILL signal when reaching hard limit
> + *    of CPU time.
> + *
> + * Note:
> + * This is also a regression test for the following kernel bug:
> + * 'c3bca5d450b62 ("posix-cpu-timers: Ensure set_process_cpu_timer is always evaluated")'
> + */
> +
> +#define _GNU_SOURCE
> +#include <errno.h>
> +#include <sys/types.h>
> +#include <unistd.h>
> +#include <sys/time.h>
> +#include <sys/resource.h>
> +#include <sys/wait.h>
> +
> +#include "tst_test.h"
> +
> +static volatile int end;
> +
> +static void sighandler(int sig)
> +{
> +	end = sig;
> +}
> +
> +static void setup(void)
> +{
> +	SAFE_SIGNAL(SIGALRM, SIG_DFL);

The SIGALRM handler should be set to SIG_DFL for the test process in the
test library. At least that's what we do in fork_testrun() function in
tst_test.c

> +	SAFE_SIGNAL(SIGXCPU, sighandler);
> +}
> +
> +static void verify_setrlimit(void)
> +{
> +	int status;
> +	pid_t pid;
> +
> +	pid = vfork();
> +	if (pid == -1)
> +		tst_brk(TBROK, "vfork() failed");

Why vfork? You are not supposed to use vfork() for anything but vfork()
+ exec(). As it is the code below invokes undefined behavior.

> +	if (!pid) {
> +		struct rlimit rlim = {
> +			.rlim_cur = 2,
> +			.rlim_max = 3,
> +		};
> +
> +		TEST(setrlimit(RLIMIT_CPU, &rlim));
> +		if (TST_RET == -1) {
> +			tst_res(TFAIL | TTERRNO,
> +				"setrlimit(RLIMIT_CPU) failed");
> +			_exit(1);
> +		}
> +
> +		alarm(10);
> +
> +		while (1);
> +	}
> +
> +	SAFE_WAITPID(pid, &status, 0);
> +
> +	if (WIFEXITED(status) && WEXITSTATUS(status) == 1)
> +		return;
> +
> +	if (WIFSIGNALED(status)) {
> +		if (WTERMSIG(status) == SIGKILL && end == SIGXCPU) {
> +			tst_res(TPASS,
> +				"Process received SIGXCPU and SIGKILL when reaching soft and hard limit of CPU time");

This message is far too long, please be short and to the point,
somethig as:

	tst_res(TPASS, "Got SIGXCPU then SIGKILL after reaching both limits");

> +			return;
> +		}
> +
> +		if (WTERMSIG(status) == SIGKILL && !end) {
> +			tst_res(TFAIL,
> +				"Process only received SIGKILL when reaching CPU time hard limit");

Here as well, something as:

	tst_res(TFAIL, "Got only SIGKILL after reaching both limits");

> +			return;
> +		}
> +
> +		if (WTERMSIG(status) == SIGALRM && end == SIGXCPU) {
> +			tst_res(TFAIL,
> +				"Process only received SIGXCPU when reaching CPU time soft limit");

And here as well.

> +			return;
> +		}
> +
> +		if (WTERMSIG(status) == SIGALRM && !end) {
> +			tst_res(TFAIL,
> +				"Process didn't receive any signal when reaching soft and hard limit of CPU time");

And here as well.

> +			return;
> +		}
> +	}
> +
> +	tst_res(TBROK, "child %s", tst_strstatus(status));
> +}
> +
> +static struct tst_test test = {
> +	.test_all = verify_setrlimit,
> +	.setup = setup,
> +};

-- 
Cyril Hrubis
chrubis@suse.cz