Re: [LTP] [PATCH v4] Refactor fork14 using new LTP API

[Petr Vorel <pvorel@suse.cz>]

Hi Andrea,

generally LGTM.
With using .skip_in_compat and SPDX GPL-2.0-only:

Reviewed-by: Petr Vorel <pvorel@suse.cz>

Minor notes below.

> ---
> Reverted SAFE_MMAP to mmap
> Added kernel tags
+1

>  testcases/kernel/syscalls/fork/fork14.c | 208 +++++++++++-------------
...
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
>   * Copyright (C) 2014  Red Hat, Inc.
> + * Copyright (C) 2023 SUSE LLC Andrea Cervesato <andrea.cervesato@suse.com>
> + */
> +
> +/*\
> + * [Description]
>   *
> - * This program is free software; you can redistribute it and/or
> - * modify it under the terms of version 2 of the GNU General Public
> - * License as published by the Free Software Foundation.

This is GPL-2.0-only.
> - *
> - * This program is distributed in the hope that it would be useful,
> - * but WITHOUT ANY WARRANTY; without even the implied warranty of
> - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> - *
> - * Further, this software is distributed without any warranty that it
> - * is free of the rightful claim of any third person regarding
> - * infringement or the like.  Any license provided herein, whether
> - * implied or otherwise, applies only to this software file.  Patent
> - * licenses, if any, provided herein do not apply to combinations of
> - * this program with other software, or any other product whatsoever.
> - *
> - * You should have received a copy of the GNU General Public License
> - * along with this program; if not, write the Free Software
> - * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
> - * 02110-1301, USA.
> - *
> - * This test is a reporducer for this patch:
> - *              https://lkml.org/lkml/2012/4/24/328
> + * This test is a reporducer for this patch: https://lkml.org/lkml/2012/4/24/328
very nit: I would trust lore more, thus I would use

https://lore.kernel.org/lkml/1335289853-2923-1-git-send-email-siddhesh.poyarekar@gmail.com/

>   * Since vma length in dup_mmap is calculated and stored in a unsigned
>   * int, it will overflow when length of mmaped memory > 16 TB. When
> - * overflow occur, fork will  incorrectly succeed. The patch above
> - * fixed it.
> - ********************************************************************/
> + * overflow occur, fork will incorrectly succeed. The patch above fixed it.
s/occur/occurs/

> + */

> -#include <sys/mman.h>
> -#include <sys/wait.h>
> -#include <stdio.h>
> -#include <unistd.h>
> -#include "test.h"
> -#include "safe_macros.h"
> -#include "lapi/abisize.h"
> +#include "tst_test.h"

> -char *TCID = "fork14";
> -int TST_TOTAL = 1;
> +#ifndef TST_ABI32

We can use .skip_in_compat = 1, flag instead.

> -#define GB		(1024 * 1024 * 1024L)
> +#include <stdlib.h>
> +#include <sys/wait.h>

> -/* set mmap threshold to 16TB */
>  #define LARGE		(16 * 1024)
>  #define EXTENT		(16 * 1024 + 10)

> -static char **pointer_vec;
> +static char **memvec;

> -static void setup(void);
> -static void cleanup(void);
> -static int  fork_test(void);
> -
> -int main(int ac, char **av)
> +static void run(void)
>  {
> -	int lc, reproduced;
> +	int i, j, ret;
> +	pid_t pid;
> +	void *mem;
> +	int prev_failed = 0;
> +	int passed = 1;
> +	int failures = 0;

> +	for (i = 0; i < EXTENT; i++) {
I wonder if the code would not be slightly more readable if the content of the
loop was in the separate function. Probably not, feel free to ignore.

> +		mem = mmap(NULL, 1 * TST_GB,
> +			PROT_READ | PROT_WRITE,
> +			MAP_PRIVATE | MAP_ANONYMOUS,
> +			0, 0);
...
> +		if (mem == MAP_FAILED) {
> +			failures++;
...
> +			if (failures > 10) {
> +				tst_brk(TCONF, "mmap() fails too many "
> +					"times, so it's almost impossible to "
> +					"get a vm_area_struct sized 16TB.");
> +			}

> -static void cleanup(void)
> -{
> -	free(pointer_vec);
> -}
> +			continue;
> +		}


> -		switch (tst_fork()) {
> -		case -1:
> -			prev_failed = 1;
> -		break;
> -		case 0:
> +		if (!pid)
>  			exit(0);
> -		default:
> -			SAFE_WAITPID(cleanup, -1, NULL, 0);

> -			if (prev_failed > 0 && i >= LARGE) {
> -				tst_resm(TFAIL, "Fork succeeds incorrectly");
> -				reproduced = 1;
> -				goto clear_memory_map;
> -			}
> +		ret = waitpid(pid, NULL, 0);
Why not SAFE_WAITPID() as it was originally?

> +		if (ret == -1 && errno != ECHILD)
> +			tst_brk(TBROK | TERRNO, "waitpid() error");
> +
> +		if (prev_failed && i >= LARGE) {
> +			passed = 0;
> +			break;
>  		}
> +
> +		prev_failed = 0;
> +
> +		tst_res(TINFO, "fork() passed at %d attempt", i);
> +	}
> +
> +	for (j = 0; j < i; j++) {
> +		if (memvec[j])
> +			SAFE_MUNMAP(memvec[j], 1 * TST_GB);
>  	}

> -clear_memory_map:
> -	for (j = 0; j < cnt; j++) {
> -		if (pointer_vec[j])
> -			SAFE_MUNMAP(cleanup, pointer_vec[j], 1 * GB);
> +	if (passed)
> +		tst_res(TPASS, "fork() failed as expected");
> +	else
> +		tst_res(TFAIL, "fork() succeeded incorrectly");
> +}
> +
> +static void setup(void)
> +{
> +	memvec = SAFE_MALLOC(EXTENT * sizeof(char *));
> +	memset(memvec, 0, EXTENT);
> +}
> +
> +static void cleanup(void)
> +{
> +	for (long i = 0; i < EXTENT; i++) {
> +		if (memvec && memvec[i])
> +			SAFE_MUNMAP(memvec[i], 1 * TST_GB);
>  	}

> -	return reproduced;
> +	if (memvec)
> +		free(memvec);
>  }
> +
> +static struct tst_test test = {
> +	.test_all = run,
> +	.setup = setup,
> +	.cleanup = cleanup,
> +	.forks_child = 1,
> +	.tags = (const struct tst_tag[]) {
> +		{"linux-git", "7edc8b0ac16cbaed7cb4ea4c6b95ce98d2997e84"},
nit: we usually use shorter hash 7edc8b0ac16c (as used in Fixes: in git
commits).

> +		{}
> +	}
> +};
> +
> +#else /* TST_ABI32 */
> +	TST_TEST_TCONF("Test doesn't supports 32bits architecture");
s/supports/support/

But we can use .skip_in_compat = 1, flag instead.

Kind regards,
Petr

> +#endif

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