Re: [LTP] [PATCH] container: new testcase pidns32

[Jan Stancek <jstancek@redhat.com>]

----- Original Message -----
> From: "Yuan Sun" <sunyuan3@huawei.com>
> To: jstancek@redhat.com
> Cc: ltp-list@lists.sourceforge.net
> Sent: Wednesday, 22 July, 2015 3:00:25 PM
> Subject: [PATCH] container: new testcase pidns32
> 

Hi,

> Kernel imposes a limit of 32 nested levels of pid namespaces.

I have some concerns about this number. It looks more like
implementation detail. Also it doesn't seem to apply for all
kernels out there.

> 
> Signed-off-by: Yuan Sun <sunyuan3@huawei.com>
> ---
>  testcases/kernel/containers/pidns/.gitignore |   1 +
>  testcases/kernel/containers/pidns/pidns32.c  | 113

You're missing runtest entry.

>  +++++++++++++++++++++++++++
>  2 files changed, 114 insertions(+)
>  create mode 100644 testcases/kernel/containers/pidns/pidns32.c
> 
> diff --git a/testcases/kernel/containers/pidns/.gitignore
> b/testcases/kernel/containers/pidns/.gitignore
> index e56c1f9..488b045 100644
> --- a/testcases/kernel/containers/pidns/.gitignore
> +++ b/testcases/kernel/containers/pidns/.gitignore
> @@ -12,3 +12,4 @@
>  /pidns20
>  /pidns30
>  /pidns31
> +/pidns32
> diff --git a/testcases/kernel/containers/pidns/pidns32.c
> b/testcases/kernel/containers/pidns/pidns32.c
> new file mode 100644
> index 0000000..8a4459b
> --- /dev/null
> +++ b/testcases/kernel/containers/pidns/pidns32.c
> @@ -0,0 +1,113 @@
> +/*
> + * Copyright (c) Huawei Technologies Co., Ltd., 2015
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + *  (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
> + * the GNU General Public License for more details.
> + */
> +
> +/*
> + * Verify that:
> + * The kernel imposes a limit of 32 nested levels of pid namespaces.
> + */
> +
> +#define _GNU_SOURCE
> +#include <sys/wait.h>
> +#include <assert.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <unistd.h>
> +#include <string.h>
> +#include <errno.h>
> +#include "test.h"
> +#include "pidns_helper.h"
> +
> +#define MAXNEST 32
> +
> +char *TCID = "pidns32";
> +int TST_TOTAL = 1;
> +
> +static void setup(void)
> +{

This should probably include tst_require_root too, since CLONE_NEWPID requires CAP_SYS_ADMIN.

> +	check_newpid();
> +	tst_tmpdir();
> +}
> +
> +static void cleanup(void)
> +{
> +	tst_rmdir();
> +}
> +
> +static int child_fn1(void *arg)
> +{
> +	pid_t cpid1;
> +	long level = (long)arg;
> +
> +	cpid1 = ltp_clone_quick(CLONE_NEWPID | SIGCHLD,
> +		(void *)child_fn1, (void *)(level + 1));

You are relying on clone failing and you check level only after that.
If I take sufficiently old kernel (which doesn't impose 32 levels as maximum),
the testcase runs until it's killed by OOM.

> +	if (cpid1 < 0) {
> +		if (level == (MAXNEST))
> +			return 0;
> +		return 1;
> +	}
> +	if (waitpid(cpid1, NULL, 0) == -1)
> +		return 1;
> +	return 0;
> +}
> +
> +static int wait4child(pid_t pid, const char *msg)
> +{
> +	int status;
> +
> +	if (waitpid(pid, &status, 0) == -1) {
> +		tst_brkm(TBROK | TERRNO, cleanup, "waitpid");
> +	} else if (WIFSIGNALED(status)) {
> +		tst_resm(TFAIL, "%s: child was killed with signal = %d",
> +			msg, WTERMSIG(status));
> +		return WTERMSIG(status);
> +	} else if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
> +		tst_resm(TFAIL, "%s: child returns %d", msg, status);
> +		return WEXITSTATUS(status);
> +	}
> +
> +	return 0;
> +}
> +
> +static void test_max_nest(void)
> +{
> +	pid_t cpid1;
> +	int status;
> +
> +	cpid1 = ltp_clone_quick(CLONE_NEWPID | SIGCHLD,
> +		(void *)child_fn1, (void *)1);
> +	if (cpid1 < 0)
> +		tst_brkm(TBROK | TERRNO, cleanup, "clone failed");
> +
> +	status = 0;
> +	status |= wait4child(cpid1, "child1");
> +	if (status == 0)
> +		tst_resm(TPASS, "The function works well.");
> +	else
> +		tst_resm(TFAIL, "Some child reported failure.");

This can be replaced by using tst_record_childstatus().

Regards,
Jan

> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	int lc;
> +
> +	setup();
> +	tst_parse_opts(argc, argv, NULL, NULL);
> +
> +	for (lc = 0; TEST_LOOPING(lc); lc++) {
> +		tst_count = 0;
> +		test_max_nest();
> +	}
> +
> +	cleanup();
> +	tst_exit();
> +}
> --
> 1.9.1
> 
> 

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