[LTP] [PATCH v1] Refactor getdtablesize01 using new LTP API
Andrea Cervesato
andrea.cervesato@suse.com
Thu Nov 16 15:43:57 CET 2023
Hi!
On 10/19/23 09:53, Richard Palethorpe wrote:
> Hello,
>
> Andrea Cervesato <andrea.cervesato@suse.de> writes:
>
>> From: Andrea Cervesato <andrea.cervesato@suse.com>
>>
>> Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
>> ---
>> .../syscalls/getdtablesize/getdtablesize01.c | 146 +++++++-----------
>> 1 file changed, 52 insertions(+), 94 deletions(-)
>>
>> diff --git a/testcases/kernel/syscalls/getdtablesize/getdtablesize01.c b/testcases/kernel/syscalls/getdtablesize/getdtablesize01.c
>> index d25cac261..80321e24f 100644
>> --- a/testcases/kernel/syscalls/getdtablesize/getdtablesize01.c
>> +++ b/testcases/kernel/syscalls/getdtablesize/getdtablesize01.c
>> @@ -1,119 +1,77 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> /*
>> * Copyright (c) International Business Machines Corp., 2005
>> * Copyright (c) Wipro Technologies Ltd, 2005. All Rights Reserved.
>> - *
>> - * 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 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.
>> - *
>> - * 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.
>> - *
>> + * Prashant P Yendigeri <prashant.yendigeri@wipro.com>
>> + * Robbie Williamson <robbiew@us.ibm.com>
>> + * Copyright (C) 2023 SUSE LLC Andrea Cervesato <andrea.cervesato@suse.com>
>> */
>> -/**********************************************************
>> - *
>> - * TEST IDENTIFIER : getdtablesize01
>> - *
>> - * EXECUTED BY : root / superuser
>> - *
>> - * TEST TITLE : Basic tests for getdtablesize01(2)
>> - *
>> - * TEST CASE TOTAL : 1
>> - *
>> - * AUTHOR : Prashant P Yendigeri
>> - * <prashant.yendigeri@wipro.com>
>> - * Robbie Williamson
>> - * <robbiew@us.ibm.com>
>> - *
>> - * DESCRIPTION
>> - * This is a Phase I test for the getdtablesize01(2) system call.
>> - * It is intended to provide a limited exposure of the system
>> call.
> It seems this test has been broken for a long time unless I am
> mistaken. glibc does not call the actual syscall, it calls
> prlimit. Which has different behaviour (see below).
>
>> - *
>> - **********************************************************/
>>
>> -#include <stdio.h>
>> -#include <errno.h>
>> -#include <sys/types.h>
>> -#include <sys/stat.h>
>> -#include <fcntl.h>
>> -#include <sys/time.h>
>> -#include <sys/resource.h>
>> -#include <unistd.h>
>> -#include "test.h"
>> +/*\
>> + * [Description]
>> + *
>> + * This test verifies that getdtablesize() syscall returns the right max number
>> + * of files which can be opened by a process. We test this in 2 ways: firstly by
>> + * comparing its return value with RLIMIT_NOFILE, secondly by opening as many
>> + * files as possible and then checking when open() raises EMFILE.
>> + */
>>
>> -void setup();
>> -void cleanup();
>> +#include <stdlib.h>
>> +#include "tst_test.h"
>>
>> -char *TCID = "getdtablesize01";
>> -int TST_TOTAL = 1;
>> +#define FILENAME "rofile"
>>
>> -int main(void)
>> +static void run(void)
>> {
>> - int table_size, fd = 0, count = 0;
>> - int max_val_opfiles;
>> + int *fds;
>> + int overfd;
>> + int open_files;
>> struct rlimit rlp;
>>
>> - setup();
>> - table_size = getdtablesize();
>> - getrlimit(RLIMIT_NOFILE, &rlp);
>> - max_val_opfiles = (rlim_t) rlp.rlim_cur;
>> -
>> - tst_resm(TINFO,
>> - "Maximum number of files a process can have opened is %d",
>> - table_size);
>> - tst_resm(TINFO,
>> - "Checking with the value returned by getrlimit...RLIMIT_NOFILE");
>> -
>> - if (table_size == max_val_opfiles)
>> - tst_resm(TPASS, "got correct dtablesize, value is %d",
>> - max_val_opfiles);
>> - else {
>> - tst_resm(TFAIL, "got incorrect table size, value is %d",
>> - max_val_opfiles);
>> - cleanup();
>> - }
>> + SAFE_GETRLIMIT(RLIMIT_NOFILE, &rlp);
>> +
>> + TST_EXP_EQ_LI(getdtablesize(), rlp.rlim_cur);
> The actual syscall may not be equal to the prlimit AFAICT (this can be
> tested using the prlimit command).
>
> The table size can be set with a system wide sysctl /proc/sys/fs/nr_open
> defined in fs/file_table.c. This is used to set the initial prlimit, but
> can be reduced.
>
>> +
>> + tst_res(TINFO, "Start opening as many files as possible");
>> +
>> + overfd = rlp.rlim_cur + 5;
>>
>> - tst_resm(TINFO,
>> - "Checking Max num of files that can be opened by a process.Should be: RLIMIT_NOFILE - 1");
>> - for (;;) {
>> - fd = open("/etc/hosts", O_RDONLY);
>> + fds = (int *)SAFE_MALLOC(overfd * sizeof(int));
>>
>> - if (fd == -1)
>> + for (open_files = 0; open_files < overfd; open_files++) {
>> + TEST(open(FILENAME, O_RDONLY));
>> +
>> + if (TST_RET == -1 && TST_ERR == EMFILE) {
> This could also fail with ENOMEM at least. Especially in a memcg and
> arch with large page sizes if there are any page sized allocations.
>
> Perhaps on some FS there would be other limits as well, resulting in a
> different error, but you can ignore that for now if you want.
>
>> + tst_res(TINFO, "Reached max amount of open files per process");
>> break;
>> - count = fd;
>> + }
>>
>> -#ifdef DEBUG
>> - printf("Opened file num %d\n", fd);
>> -#endif
>> + fds[open_files] = TST_RET;
>> }
>>
>> -//Now the max files opened should be RLIMIT_NOFILE - 1 , why ? read getdtablesize man page
>> + --open_files;
>>
>> - if (count > 0)
>> - close(count);
>> - if (count == (max_val_opfiles - 1))
>> - tst_resm(TPASS, "%d = %d", count, (max_val_opfiles - 1));
>> - else if (fd < 0 && errno == ENFILE)
>> - tst_brkm(TCONF, cleanup, "Reached maximum number of open files for the system");
>> - else
>> - tst_resm(TFAIL, "%d != %d", count, (max_val_opfiles - 1));
>> + tst_res(TINFO, "Opened %d files", open_files);
>>
>> - cleanup();
>> - tst_exit();
>> -}
>> + for (int i = 0; i <= open_files; i++)
>> + SAFE_CLOSE(fds[i]);
>>
>> -void setup(void)
>> -{
>> - tst_sig(NOFORK, DEF_HANDLER, cleanup);
>> + free(fds);
>>
>> - TEST_PAUSE;
>> + TST_EXP_EXPR(getdtablesize() >= open_files,
>> + "max amount of open files per process hasn't been overflowed");
>> }
>>
>> -void cleanup(void)
>> +static void setup(void)
>> {
>> + int fd;
>> +
>> + fd = SAFE_CREAT(FILENAME, 0644);
>> + SAFE_CLOSE(fd);
>> }
>> +
>> +static struct tst_test test = {
>> + .test_all = run,
>> + .setup = setup,
>> + .needs_tmpdir = 1,
> This tests the underlying file system to some extent, so we should test
> all available file systems.
>
>> +};
>> --
>> 2.35.3
>
I think we can just remove this test, since the syscall number is not
even defined in the kernel and glibc only use prlimit. I don't know,
what do you think?
Andrea
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