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1/* Check if clone (CLONE_THREAD) does not call exit_group (BZ #21512)
2 Copyright (C) 2017-2019 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
18
19#include <string.h>
20#include <sched.h>
21#include <signal.h>
22#include <unistd.h>
23#include <sys/syscall.h>
24#include <sys/wait.h>
25#include <sys/types.h>
26#include <linux/futex.h>
27
28#include <stackinfo.h> /* For _STACK_GROWS_{UP,DOWN}. */
29#include <support/check.h>
30#include <stdatomic.h>
31
32/* Test if clone call with CLONE_THREAD does not call exit_group. The 'f'
33 function returns '1', which will be used by clone thread to call the
34 'exit' syscall directly. If _exit is used instead, exit_group will be
35 used and thus the thread group will finish with return value of '1'
36 (where '2' from main thread is expected. */
37
38static int
39f (void *a)
40{
41 return 1;
42}
43
44/* Futex wait for TID argument, similar to pthread_join internal
45 implementation. */
46#define wait_tid(ctid_ptr, ctid_val) \
47 do { \
48 __typeof (*(ctid_ptr)) __tid; \
49 /* We need acquire MO here so that we synchronize with the \
50 kernel's store to 0 when the clone terminates. */ \
51 while ((__tid = atomic_load_explicit (ctid_ptr, \
52 memory_order_acquire)) != 0) \
53 futex_wait (ctid_ptr, ctid_val); \
54 } while (0)
55
56static inline int
57futex_wait (int *futexp, int val)
58{
59 return syscall (__NR_futex, futexp, FUTEX_WAIT, val);
60}
61
62static int
63do_test (void)
64{
65 char st[1024] __attribute__ ((aligned));
66 int clone_flags = CLONE_THREAD;
67 /* Minimum required flags to used along with CLONE_THREAD. */
68 clone_flags |= CLONE_VM | CLONE_SIGHAND;
69 /* We will used ctid to call on futex to wait for thread exit. */
70 clone_flags |= CLONE_CHILD_CLEARTID;
71 /* Initialize with a known value. ctid is set to zero by the kernel after the
72 cloned thread has exited. */
73#define CTID_INIT_VAL 1
74 pid_t ctid = CTID_INIT_VAL;
75 pid_t tid;
76
77#ifdef __ia64__
78 extern int __clone2 (int (*__fn) (void *__arg), void *__child_stack_base,
79 size_t __child_stack_size, int __flags,
80 void *__arg, ...);
81 tid = __clone2 (f, st, sizeof (st), clone_flags, NULL, /* ptid */ NULL,
82 /* tls */ NULL, &ctid);
83#else
84#if _STACK_GROWS_DOWN
85 tid = clone (f, st + sizeof (st), clone_flags, NULL, /* ptid */ NULL,
86 /* tls */ NULL, &ctid);
87#elif _STACK_GROWS_UP
88 tid = clone (f, st, clone_flags, NULL, /* ptid */ NULL, /* tls */ NULL,
89 &ctid);
90#else
91#error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
92#endif
93#endif
94 if (tid == -1)
95 FAIL_EXIT1 ("clone failed: %m");
96
97 wait_tid (&ctid, CTID_INIT_VAL);
98
99 return 2;
100}
101
102#define EXPECTED_STATUS 2
103#include <support/test-driver.c>
104

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