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e373e5f007
When delivering urgent signals to the current thread we need to check if we should be unblocked, and if not we need to yield to another process. We also need to make sure that we suppress context switches during Process::exec() so that we don't clobber the registers that it sets up (eip mainly) by a context switch. To be able to do that we add the concept of a critical section, which are similar to Process::m_in_irq but different in that they can be requested at any time. Calls to Scheduler::yield and Scheduler::donate_to will return instantly without triggering a context switch, but the processor will then asynchronously trigger a context switch once the critical section is left.
89 lines
2.5 KiB
C++
89 lines
2.5 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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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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void WaitQueue::enqueue(Thread& thread)
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{
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ScopedCritical critical;
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m_threads.append(thread);
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}
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void WaitQueue::wake_one(Atomic<bool>* lock)
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{
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ScopedCritical critical;
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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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return;
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if (auto* thread = m_threads.take_first())
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thread->wake_from_queue();
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Scheduler::yield();
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}
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void WaitQueue::wake_n(i32 wake_count)
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{
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ScopedCritical critical;
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if (m_threads.is_empty())
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return;
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for (i32 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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thread->wake_from_queue();
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}
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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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ScopedCritical critical;
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if (m_threads.is_empty())
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return;
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while (!m_threads.is_empty())
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m_threads.take_first()->wake_from_queue();
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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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ScopedCritical critical;
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m_threads.clear();
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}
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}
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