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/* Check if clone (CLONE_THREAD) does not call exit_group (BZ #21512)
Copyright (C) 2017-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <string.h>
#include <sched.h>
#include <signal.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <linux/futex.h>
#include <stackinfo.h> /* For _STACK_GROWS_{UP,DOWN}. */
#include <support/check.h>
#include <stdatomic.h>
/* Test if clone call with CLONE_THREAD does not call exit_group. The 'f'
function returns '1', which will be used by clone thread to call the
'exit' syscall directly. If _exit is used instead, exit_group will be
used and thus the thread group will finish with return value of '1'
(where '2' from main thread is expected. */
static int
f (void *a)
{
return 1;
}
/* Futex wait for TID argument, similar to pthread_join internal
implementation. */
#define wait_tid(ctid_ptr, ctid_val) \
do { \
__typeof (*(ctid_ptr)) __tid; \
/* We need acquire MO here so that we synchronize with the \
kernel's store to 0 when the clone terminates. */ \
while ((__tid = atomic_load_explicit (ctid_ptr, \
memory_order_acquire)) != 0) \
futex_wait (ctid_ptr, ctid_val); \
} while (0)
static inline int
futex_wait (int *futexp, int val)
{
#ifdef __NR_futex
return syscall (__NR_futex, futexp, FUTEX_WAIT, val);
#else
return syscall (__NR_futex_time64, futexp, FUTEX_WAIT, val);
#endif
}
static int
do_test (void)
{
char st[1024] __attribute__ ((aligned));
int clone_flags = CLONE_THREAD;
/* Minimum required flags to used along with CLONE_THREAD. */
clone_flags |= CLONE_VM | CLONE_SIGHAND;
/* We will used ctid to call on futex to wait for thread exit. */
clone_flags |= CLONE_CHILD_CLEARTID;
/* Initialize with a known value. ctid is set to zero by the kernel after the
cloned thread has exited. */
#define CTID_INIT_VAL 1
pid_t ctid = CTID_INIT_VAL;
pid_t tid;
#ifdef __ia64__
extern int __clone2 (int (*__fn) (void *__arg), void *__child_stack_base,
size_t __child_stack_size, int __flags,
void *__arg, ...);
tid = __clone2 (f, st, sizeof (st), clone_flags, NULL, /* ptid */ NULL,
/* tls */ NULL, &ctid);
#else
#if _STACK_GROWS_DOWN
tid = clone (f, st + sizeof (st), clone_flags, NULL, /* ptid */ NULL,
/* tls */ NULL, &ctid);
#elif _STACK_GROWS_UP
tid = clone (f, st, clone_flags, NULL, /* ptid */ NULL, /* tls */ NULL,
&ctid);
#else
#error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
#endif
#endif
if (tid == -1)
FAIL_EXIT1 ("clone failed: %m");
wait_tid (&ctid, CTID_INIT_VAL);
return 2;
}
#define EXPECTED_STATUS 2
#include <support/test-driver.c>
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