mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-12 06:10:10 +00:00
16adc58e73
Keep __exit_funcs_lock almost all the time and unlock it only to execute callbacks. This fixed two issues. 1. f->func.cxa was modified outside the lock with rare data race like: thread 0: __run_exit_handlers unlock __exit_funcs_lock thread 1: __internal_atexit locks __exit_funcs_lock thread 0: f->flavor = ef_free; thread 1: sees ef_free and use it as new thread 1: new->func.cxa.fn = (void (*) (void *, int)) func; thread 1: new->func.cxa.arg = arg; thread 1: new->flavor = ef_cxa; thread 0: cxafct = f->func.cxa.fn; // it's wrong fn! thread 0: cxafct (f->func.cxa.arg, status); // it's wrong arg! thread 0: goto restart; thread 0: call the same exit_function again as it's ef_cxa 2. Don't unlock in main while loop after *listp = cur->next. If *listp is NULL and __exit_funcs_done is false another thread may fail in __new_exitfn on assert (l != NULL): thread 0: *listp = cur->next; // It can be the last: *listp = NULL. thread 0: __libc_lock_unlock thread 1: __libc_lock_lock in __on_exit thread 1: __new_exitfn thread 1: if (__exit_funcs_done) // false: thread 0 isn't there yet. thread 1: l = *listp thread 1: moves one and crashes on assert (l != NULL); The test needs multiple iterations to consistently fail without the fix. Fixes https://sourceware.org/bugzilla/show_bug.cgi?id=27749 Checked on x86_64-linux-gnu. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
111 lines
2.8 KiB
C
111 lines
2.8 KiB
C
/* Support file for atexit/exit, etc. race tests (BZ #27749).
|
|
Copyright (C) 2021 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/>. */
|
|
|
|
/* The atexit/exit, at_quick_exit/quick_exit, __cxa_atexit/exit, etc.
|
|
exhibited data race while calling destructors.
|
|
|
|
This test registers destructors from the background thread, and checks that
|
|
the same destructor is not called more than once. */
|
|
|
|
#include <stdatomic.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <support/check.h>
|
|
#include <support/xthread.h>
|
|
#include <support/xunistd.h>
|
|
#include <sys/wait.h>
|
|
#include <unistd.h>
|
|
|
|
static atomic_int registered;
|
|
static atomic_int todo = 100000;
|
|
|
|
static void
|
|
atexit_cb (void *arg)
|
|
{
|
|
atomic_fetch_sub (®istered, 1);
|
|
static void *prev;
|
|
if (arg == prev)
|
|
FAIL_EXIT1 ("%s: %p\n", __func__, arg);
|
|
prev = arg;
|
|
|
|
while (atomic_load (&todo) > 0 && atomic_load (®istered) < 100)
|
|
;
|
|
}
|
|
|
|
int __cxa_atexit (void (*func) (void *), void *arg, void *d);
|
|
|
|
static void *
|
|
thread_func (void *arg)
|
|
{
|
|
void *cb_arg = NULL;
|
|
while (atomic_load (&todo) > 0)
|
|
{
|
|
if (atomic_load (®istered) < 10000)
|
|
{
|
|
int n = 10;
|
|
for (int i = 0; i < n; ++i)
|
|
__cxa_atexit (&atexit_cb, ++cb_arg, 0);
|
|
atomic_fetch_add (®istered, n);
|
|
atomic_fetch_sub (&todo, n);
|
|
}
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
_Noreturn static void
|
|
test_and_exit (void)
|
|
{
|
|
pthread_attr_t attr;
|
|
|
|
xpthread_attr_init (&attr);
|
|
xpthread_attr_setdetachstate (&attr, 1);
|
|
|
|
xpthread_create (&attr, thread_func, NULL);
|
|
xpthread_attr_destroy (&attr);
|
|
|
|
while (atomic_load (®istered) == 0)
|
|
;
|
|
exit (0);
|
|
}
|
|
|
|
static int
|
|
do_test (void)
|
|
{
|
|
for (int i = 0; i < 20; ++i)
|
|
{
|
|
for (int i = 0; i < 10; ++i)
|
|
if (xfork () == 0)
|
|
test_and_exit ();
|
|
|
|
for (int i = 0; i < 10; ++i)
|
|
{
|
|
int status;
|
|
xwaitpid (0, &status, 0);
|
|
if (!WIFEXITED (status))
|
|
FAIL_EXIT1 ("Failed iterations %d", i);
|
|
TEST_COMPARE (WEXITSTATUS (status), 0);
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
#define TEST_FUNCTION do_test
|
|
#include <support/test-driver.c>
|