c3f114037d
<pthread.h> was missing nonnull attributes, noreturn on pthread_exit, and had incorrect cv qualifiers for several standard functions. I've also marked the non-standard stuff (where I count glibc rather than POSIX as "standard") so we can revisit this cruft for LP64 and try to ensure we're compatible with glibc. I've also broken out the pthread_cond* functions into a new file. I've made the remaining pthread files (plus ptrace) part of the bionic code and fixed all the warnings. I've added a few more smoke tests for chunks of untested pthread functionality. We no longer need the libc_static_common_src_files hack for any of the pthread implementation because we long since stripped out the rest of the armv5 support, and this hack was just to ensure that __get_tls in libc.a went via the kernel if necessary. This patch also finishes the job of breaking up the pthread.c monolith, and adds a handful of new tests. Change-Id: Idc0ae7f5d8aa65989598acd4c01a874fe21582c7
100 lines
3.6 KiB
C++
100 lines
3.6 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 <pthread.h>
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#include "private/bionic_atomic_inline.h"
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#include "private/bionic_futex.h"
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#define ONCE_INITIALIZING (1 << 0)
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#define ONCE_COMPLETED (1 << 1)
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/* NOTE: this implementation doesn't support a init function that throws a C++ exception
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* or calls fork()
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*/
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int pthread_once(pthread_once_t* once_control, void (*init_routine)(void)) {
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volatile pthread_once_t* once_control_ptr = once_control;
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// PTHREAD_ONCE_INIT is 0, we use the following bit flags
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// bit 0 set -> initialization is under way
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// bit 1 set -> initialization is complete
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// First check if the once is already initialized. This will be the common
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// case and we want to make this as fast as possible. Note that this still
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// requires a load_acquire operation here to ensure that all the
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// stores performed by the initialization function are observable on
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// this CPU after we exit.
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if (__predict_true((*once_control_ptr & ONCE_COMPLETED) != 0)) {
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ANDROID_MEMBAR_FULL();
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return 0;
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}
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while (true) {
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// Try to atomically set the INITIALIZING flag.
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// This requires a cmpxchg loop, and we may need
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// to exit prematurely if we detect that
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// COMPLETED is now set.
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int32_t old_value, new_value;
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do {
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old_value = *once_control_ptr;
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if ((old_value & ONCE_COMPLETED) != 0) {
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break;
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}
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new_value = old_value | ONCE_INITIALIZING;
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} while (__bionic_cmpxchg(old_value, new_value, once_control_ptr) != 0);
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if ((old_value & ONCE_COMPLETED) != 0) {
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// We detected that COMPLETED was set while in our loop.
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ANDROID_MEMBAR_FULL();
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return 0;
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}
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if ((old_value & ONCE_INITIALIZING) == 0) {
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// We got there first, we can jump out of the loop to handle the initialization.
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break;
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}
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// Another thread is running the initialization and hasn't completed
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// yet, so wait for it, then try again.
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__futex_wait_ex(once_control_ptr, 0, old_value, NULL);
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}
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// Call the initialization function.
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(*init_routine)();
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// Do a store_release indicating that initialization is complete.
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ANDROID_MEMBAR_FULL();
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*once_control_ptr = ONCE_COMPLETED;
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// Wake up any waiters, if any.
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__futex_wake_ex(once_control_ptr, 0, INT_MAX);
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return 0;
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}
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