877ec6d904
Let the kernel keep pthread_internal_t::tid updated, including across forks and for the main thread. This then lets us fix pthread_join to only return after the thread has really exited. Also fix the thread attributes of the main thread so we don't unmap the main thread's stack (which is really owned by the dynamic linker and contains things like environment variables), which fixes crashes when joining with an exited main thread and also fixes problems reported publicly with accessing environment variables after the main thread exits (for which I've added a new unit test). In passing I also fixed a bug where if the clone(2) inside pthread_create(3) fails, we'd unmap the child's stack and TLS (which contains the mutex) and then try to unlock the mutex. Boom! It wasn't until after I'd uploaded the fix for this that I came across a new public bug reporting this exact failure. Bug: 8206355 Bug: 11693195 Bug: https://code.google.com/p/android/issues/detail?id=57421 Bug: https://code.google.com/p/android/issues/detail?id=62392 Change-Id: I2af9cf6e8ae510a67256ad93cad891794ed0580b
79 lines
2.5 KiB
C++
79 lines
2.5 KiB
C++
/*
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* Copyright (C) 2008 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <errno.h>
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#include "private/bionic_futex.h"
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#include "pthread_accessor.h"
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int pthread_join(pthread_t t, void** return_value) {
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if (t == pthread_self()) {
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return EDEADLK;
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}
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pid_t tid;
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volatile int* tid_ptr;
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{
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pthread_accessor thread(t);
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if (thread.get() == NULL) {
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return ESRCH;
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}
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if ((thread->attr.flags & PTHREAD_ATTR_FLAG_DETACHED) != 0) {
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return EINVAL;
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}
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if ((thread->attr.flags & PTHREAD_ATTR_FLAG_JOINED) != 0) {
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return EINVAL;
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}
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// Okay, looks like we can signal our intention to join.
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thread->attr.flags |= PTHREAD_ATTR_FLAG_JOINED;
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tid = thread->tid;
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tid_ptr = &thread->tid;
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}
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// We set the PTHREAD_ATTR_FLAG_JOINED flag with the lock held,
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// so no one is going to remove this thread except us.
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// Wait for the thread to actually exit, if it hasn't already.
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while (*tid_ptr != 0) {
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__futex_wait(tid_ptr, tid, NULL);
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}
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// Take the lock again so we can pull the thread's return value
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// and remove the thread from the list.
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pthread_accessor thread(t);
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if (return_value) {
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*return_value = thread->return_value;
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}
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_pthread_internal_remove_locked(thread.get());
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return 0;
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}
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