Re: [LTP] [PATCH v1 1/2] Rewrite gettid01 test

[Andrea Cervesato via ltp <ltp@lists.linux.it>]

Hi!

On 10/5/23 10:50, Richard Palethorpe wrote:
> Hello,
>
> Andrea Cervesato <andrea.cervesato@suse.de> writes:
>
>> From: Andrea Cervesato <andrea.cervesato@suse.com>
>>
>> The old test wasn't doing anything meaningful, but just checking
>> gettid() syscall was working. In this test we checks if gettid() is
>> working and if PID differs from its return value.
>>
>> Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
>> ---
>>   testcases/kernel/syscalls/gettid/gettid01.c | 102 +++-----------------
>>   1 file changed, 14 insertions(+), 88 deletions(-)
>>
>> diff --git a/testcases/kernel/syscalls/gettid/gettid01.c b/testcases/kernel/syscalls/gettid/gettid01.c
>> index 7e5b6b175..3ee139d5f 100644
>> --- a/testcases/kernel/syscalls/gettid/gettid01.c
>> +++ b/testcases/kernel/syscalls/gettid/gettid01.c
>> @@ -1,96 +1,22 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>>   /*
>> - * Crackerjack Project
>> - *
>> - * Copyright (C) 2007-2008, Hitachi, Ltd.
>> - * Author(s): Takahiro Yasui <takahiro.yasui.mp@hitachi.com>,
>> - *            Yumiko Sugita <yumiko.sugita.yf@hitachi.com>,
>> - *            Satoshi Fujiwara <sa-fuji@sdl.hitachi.co.jp>
>> - *
>> - * 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.
>> - *
>> - * You should have received a copy of the GNU General Public License
>> - * along with this program; if not, write to the Free Software
>> - * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
>> - *
>> - * $Id: gettid01.c,v 1.5 2009/10/26 14:55:47 subrata_modak Exp $
>> + * Copyright (C) 2023 SUSE LLC Andrea Cervesato <andrea.cervesato@suse.com>
>> + */
>> +/*\
>> + * [Description]
>>    *
>> + * This test checks if parent pid is equal to tid in single-threaded
>> + * application.
>>    */
>>   
>> -/* Porting from Crackerjack to LTP is done
>> -   by Masatake YAMATO <yamato@redhat.com> */
>> -
>> -#include <sys/types.h>
>> -#include <linux/unistd.h>
>> -#include <errno.h>
>> -
>> -#include "test.h"
>> -
>> -void setup();
>> -void cleanup();
>> +#include "tst_test.h"
>> +#include "lapi/syscalls.h"
>>   
>> -char *TCID = "gettid01";
>> -
>> -int TST_TOTAL = 1;
>> -
>> -pid_t my_gettid(void)
>> +static void run(void)
>>   {
>> -	return (pid_t) syscall(__NR_gettid);
>> +	TST_EXP_EQ_LI(getpid(), tst_syscall(__NR_gettid));
> Perhaps this is nit picking, but this assumes libc didn't put us in a
> thread or just caches the wrong value in getpid. So it is more a test of
> libc than the kernel.
I understand the cache part. Probably we need to call 
tst_syscall(__NR_getpid) instead of getpid(), but I don't get the thread 
part. Is it possible that libc moves test function inside a thread?
> Is there some other way we could check that the main test process is not
> a thread? There could be some file in proc I guess. Then we are
> comparing information from multiple sources and it should all align.
>
> Also getpid could be called directly avoiding libc.
>
>>   }
>>   
>> -int main(int ac, char **av)
>> -{
>> -	int lc;
>> -
>> -	tst_parse_opts(ac, av, NULL, NULL);
>> -
>> -	setup();
>> -
>> -	/*
>> -	 * The following loop checks looping state if -c option given
>> -	 */
>> -	for (lc = 0; TEST_LOOPING(lc); lc++) {
>> -
>> -		tst_count = 0;
>> -
>> -		TEST(my_gettid());
>> -
>> -		if (TEST_RETURN == -1) {
>> -			tst_resm(TFAIL, "gettid() Failed, errno=%d: %s",
>> -				 TEST_ERRNO, strerror(TEST_ERRNO));
>> -		} else {
>> -			tst_resm(TPASS, "gettid() returned %ld",
>> -				 TEST_RETURN);
>> -		}
>> -	}
>> -
>> -	cleanup();
>> -	tst_exit();
>> -}
>> -
>> -/*
>> - * setup() - performs all ONE TIME setup for this test.
>> - */
>> -void setup(void)
>> -{
>> -
>> -	tst_sig(NOFORK, DEF_HANDLER, cleanup);
>> -
>> -	TEST_PAUSE;
>> -
>> -}
>> -
>> -/*
>> - * cleanup() - performs all ONE TIME cleanup for this test at
>> - *		completion or premature exit.
>> - */
>> -void cleanup(void)
>> -{
>> -}
>> +static struct tst_test test = {
>> +	.test_all = run,
>> +};
>> -- 
>> 2.35.3
>
Andrea


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