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c6af8a9a3c
As for exit, also allows concurrent quick_exit to avoid race conditions when it is called concurrently. Since it uses the same internal function as exit, the __exit_lock lock is moved to __run_exit_handlers. It also solved a potential concurrent when calling exit and quick_exit concurrently. The test case 'expected' is expanded to a value larger than the minimum required by C/POSIX (32 entries) so at_quick_exit() will require libc to allocate a new block. This makes the test mre likely to trigger concurrent issues (through free() at __run_exit_handlers) if quick_exit() interacts with the at_quick_exit list concurrently. This is also the latest interpretation of the Austin Ticket [1]. Checked on x86_64-linux-gnu. [1] https://austingroupbugs.net/view.php?id=1845 Reviewed-by: Carlos O'Donell <carlos@redhat.com>
161 lines
3.8 KiB
C
161 lines
3.8 KiB
C
/* Check if exit/quick_exit can be called concurrently by multiple threads.
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Copyright (C) 2024 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <array_length.h>
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#include <stdlib.h>
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#include <support/check.h>
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#include <support/xthread.h>
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#include <stdio.h>
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#include <support/xunistd.h>
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#include <string.h>
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/* A value larger than the minimum required by C/POSIX (32), to trigger a
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new block memory allocation. */
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#define MAX_atexit 64
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static pthread_barrier_t barrier;
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static void *
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tf (void *closure)
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{
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xpthread_barrier_wait (&barrier);
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EXIT (0);
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return NULL;
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}
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static const char expected[] = "00000000000000000000000000000000000"
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"00000000000000000000003021121130211";
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static char crumbs[sizeof (expected)];
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static int next_slot = 0;
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static void
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exit_with_flush (int code)
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{
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fflush (stdout);
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/* glibc allows recursive EXIT, the ATEXIT handlers execution will be
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resumed from the where the previous EXIT was interrupted. */
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EXIT (code);
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}
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/* Take some time, so another thread potentially issue EXIT. */
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#define SETUP_NANOSLEEP \
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if (nanosleep (&(struct timespec) { .tv_sec = 0, .tv_nsec = 1000L }, \
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NULL) != 0) \
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FAIL_EXIT1 ("nanosleep: %m")
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static void
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fn0 (void)
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{
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crumbs[next_slot++] = '0';
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SETUP_NANOSLEEP;
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}
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static void
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fn1 (void)
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{
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crumbs[next_slot++] = '1';
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SETUP_NANOSLEEP;
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}
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static void
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fn2 (void)
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{
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crumbs[next_slot++] = '2';
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ATEXIT (fn1);
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SETUP_NANOSLEEP;
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}
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static void
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fn3 (void)
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{
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crumbs[next_slot++] = '3';
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ATEXIT (fn2);
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ATEXIT (fn0);
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SETUP_NANOSLEEP;
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}
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static void
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fn_final (void)
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{
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TEST_COMPARE_STRING (crumbs, expected);
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exit_with_flush (0);
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}
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_Noreturn static void
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child (void)
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{
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enum { nthreads = 8 };
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xpthread_barrier_init (&barrier, NULL, nthreads + 1);
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pthread_t thr[nthreads];
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for (int i = 0; i < nthreads; i++)
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thr[i] = xpthread_create (NULL, tf, NULL);
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xpthread_barrier_wait (&barrier);
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for (int i = 0; i < nthreads; i++)
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{
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pthread_join (thr[i], NULL);
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/* It should not be reached, it means that thread did not exit for
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some reason. */
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support_record_failure ();
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}
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EXIT (2);
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}
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static int
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do_test (void)
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{
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/* Register a large number of handler that will trigger a heap allocation
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for the handle state. On EXIT, each block will be freed after the
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handle is processed. */
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int slots_remaining = MAX_atexit;
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/* Register this first so it can verify expected order of the rest. */
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ATEXIT (fn_final); --slots_remaining;
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TEST_VERIFY_EXIT (ATEXIT (fn1) == 0); --slots_remaining;
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TEST_VERIFY_EXIT (ATEXIT (fn3) == 0); --slots_remaining;
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TEST_VERIFY_EXIT (ATEXIT (fn1) == 0); --slots_remaining;
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TEST_VERIFY_EXIT (ATEXIT (fn2) == 0); --slots_remaining;
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TEST_VERIFY_EXIT (ATEXIT (fn1) == 0); --slots_remaining;
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TEST_VERIFY_EXIT (ATEXIT (fn3) == 0); --slots_remaining;
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while (slots_remaining > 0)
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{
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TEST_VERIFY_EXIT (ATEXIT (fn0) == 0); --slots_remaining;
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}
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pid_t pid = xfork ();
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if (pid != 0)
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{
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int status;
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xwaitpid (pid, &status, 0);
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TEST_VERIFY (WIFEXITED (status));
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}
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else
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child ();
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return 0;
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}
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#include <support/test-driver.c>
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