952e9eb086
Currently we use __thread variable to store thread_local_dtors, which makes tsan test fork_atexit.cc hang. The problem is as below: The main thread creates a worker thread, the worker thread calls pthread_exit() -> __cxa_thread_finalize() -> __emutls_get_address() -> pthread_once(emutls_init) -> emutls_init(). Then the main thread calls fork(), the child process cals exit() -> __cxa_thread_finalize() -> __emutls_get_address() -> pthread_once(emutls_init). So the child process is waiting for pthread_once(emutls_init) to finish which will never occur. It might be the test's fault because POSIX standard says if a multi-threaded process calls fork(), the new process may only execute async-signal-safe operations until exec functions are called. And exit() is not async-signal-safe. But we can make bionic more reliable by not using __thread in __cxa_thread_finalize(). Bug: 25392375 Change-Id: Ife403dd7379dad8ddf1859c348c1c0adea07afb3
49 lines
1.5 KiB
C++
49 lines
1.5 KiB
C++
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <sys/cdefs.h>
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#include "pthread_internal.h"
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struct thread_local_dtor {
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void (*func) (void *);
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void *arg;
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void *dso_handle; // unused...
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thread_local_dtor* next;
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};
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extern "C" int __cxa_thread_atexit_impl(void (*func) (void *), void *arg, void *dso_handle) {
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thread_local_dtor* dtor = new thread_local_dtor();
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dtor->func = func;
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dtor->arg = arg;
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dtor->dso_handle = dso_handle;
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pthread_internal_t* thread = __get_thread();
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dtor->next = thread->thread_local_dtors;
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thread->thread_local_dtors = dtor;
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return 0;
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}
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extern "C" __LIBC_HIDDEN__ void __cxa_thread_finalize() {
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pthread_internal_t* thread = __get_thread();
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while (thread->thread_local_dtors != nullptr) {
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thread_local_dtor* current = thread->thread_local_dtors;
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thread->thread_local_dtors = current->next;
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current->func(current->arg);
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delete current;
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}
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}
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