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9725bda63e
If WaitQueue::wake_all, WaitQueue::wake_one, or WaitQueue::wake_n is called but nobody is currently waiting, we should remember that fact and prevent someone from waiting after such a request. This solves a race condition where the Finalizer thread is notified to finalize a thread, but it is not (yet) waiting on this queue. Fixes #2693
147 lines
4.4 KiB
C++
147 lines
4.4 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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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 are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED 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 OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <Kernel/Thread.h>
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#include <Kernel/WaitQueue.h>
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//#define WAITQUEUE_DEBUG
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namespace Kernel {
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WaitQueue::WaitQueue()
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{
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}
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WaitQueue::~WaitQueue()
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{
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}
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bool WaitQueue::enqueue(Thread& thread)
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{
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ScopedSpinLock queue_lock(m_lock);
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if (m_wake_requested) {
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// wake_* was called when no threads were in the queue
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// we shouldn't wait at all
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m_wake_requested = false;
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#ifdef WAITQUEUE_DEBUG
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dbg() << "WaitQueue " << VirtualAddress(this) << ": enqueue: wake_all pending";
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#endif
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return false;
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}
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m_threads.append(thread);
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return true;
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}
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void WaitQueue::wake_one(Atomic<bool>* lock)
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{
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ScopedSpinLock queue_lock(m_lock);
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if (lock)
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*lock = false;
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if (m_threads.is_empty()) {
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// Save the fact that a wake was requested
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m_wake_requested = true;
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#ifdef WAITQUEUE_DEBUG
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dbg() << "WaitQueue " << VirtualAddress(this) << ": wake_one: nobody to wake, mark as pending";
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#endif
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return;
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}
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#ifdef WAITQUEUE_DEBUG
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dbg() << "WaitQueue " << VirtualAddress(this) << ": wake_one:";
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#endif
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auto* thread = m_threads.take_first();
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#ifdef WAITQUEUE_DEBUG
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dbg() << "WaitQueue " << VirtualAddress(this) << ": wake_one: wake thread " << *thread;
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#endif
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thread->wake_from_queue();
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m_wake_requested = false;
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Scheduler::yield();
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}
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void WaitQueue::wake_n(u32 wake_count)
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{
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ScopedSpinLock queue_lock(m_lock);
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if (m_threads.is_empty()) {
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// Save the fact that a wake was requested
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m_wake_requested = true;
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#ifdef WAITQUEUE_DEBUG
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dbg() << "WaitQueue " << VirtualAddress(this) << ": wake_n: nobody to wake, mark as pending";
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#endif
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return;
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}
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#ifdef WAITQUEUE_DEBUG
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dbg() << "WaitQueue " << VirtualAddress(this) << ": wake_n: " << wake_count;
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#endif
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for (u32 i = 0; i < wake_count; ++i) {
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Thread* thread = m_threads.take_first();
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if (!thread)
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break;
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#ifdef WAITQUEUE_DEBUG
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dbg() << "WaitQueue " << VirtualAddress(this) << ": wake_n: wake thread " << *thread;
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#endif
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thread->wake_from_queue();
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}
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m_wake_requested = false;
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Scheduler::yield();
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}
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void WaitQueue::wake_all()
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{
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ScopedSpinLock queue_lock(m_lock);
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if (m_threads.is_empty()) {
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// Save the fact that a wake was requested
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m_wake_requested = true;
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#ifdef WAITQUEUE_DEBUG
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dbg() << "WaitQueue " << VirtualAddress(this) << ": wake_all: nobody to wake, mark as pending";
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#endif
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return;
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}
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#ifdef WAITQUEUE_DEBUG
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dbg() << "WaitQueue " << VirtualAddress(this) << ": wake_all: ";
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#endif
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while (!m_threads.is_empty()) {
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Thread* thread = m_threads.take_first();
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#ifdef WAITQUEUE_DEBUG
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dbg() << "WaitQueue " << VirtualAddress(this) << ": wake_all: wake thread " << *thread;
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#endif
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thread->wake_from_queue();
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}
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m_wake_requested = false;
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Scheduler::yield();
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}
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void WaitQueue::clear()
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{
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ScopedSpinLock queue_lock(m_lock);
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#ifdef WAITQUEUE_DEBUG
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dbg() << "WaitQueue " << VirtualAddress(this) << ": clear";
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#endif
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m_threads.clear();
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m_wake_requested = false;
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}
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}
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