/* Check if clone (CLONE_THREAD) does not call exit_group (BZ #21512) Copyright (C) 2017-2020 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>