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Kernel: Dequeue dying threads from WaitQueue

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If a thread is waiting but getting killed, we need to dequeue
the thread from the WaitQueue so that a potential wake before
finalization doesn't happen.
This commit is contained in:
Tom 2020-08-05 19:13:28 -06:00 • committed by Andreas Kling
parent 9495eeb075
commit 41d2a0e9f7
4 changed files with 37 additions and 7 deletions
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31
Kernel/Thread.cpp
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@ -714,10 +714,20 @@ void Thread::set_state(State new_state)
ASSERT(g_scheduler_data->has_thread(*this));
}
if (m_state == Dying && this != Thread::current() && is_finalizable()) {
// Some other thread set this thread to Dying, notify the
// finalizer right away as it can be cleaned up now
Scheduler::notify_finalizer();
if (m_state == Dying) {
if (previous_state == Queued) {
// Holding the scheduler lock, we need to dequeue this thread
ASSERT(m_wait_queue != nullptr);
m_wait_queue->dequeue(*this);
m_wait_queue = nullptr;
}
if (this != Thread::current() && is_finalizable()) {
// Some other thread set this thread to Dying, notify the
// finalizer right away as it can be cleaned up now
Scheduler::notify_finalizer();
}
}
}
@ -854,6 +864,7 @@ const LogStream& operator<<(const LogStream& stream, const Thread& value)
Thread::BlockResult Thread::wait_on(WaitQueue& queue, const char* reason, timeval* timeout, Atomic<bool>* lock, Thread* beneficiary)
{
auto* current_thread = Thread::current();
TimerId timer_id {};
bool did_unlock;
@ -865,7 +876,7 @@ Thread::BlockResult Thread::wait_on(WaitQueue& queue, const char* reason, timeva
// we need to wait until the scheduler lock is released again
{
ScopedSpinLock sched_lock(g_scheduler_lock);
if (!queue.enqueue(*Thread::current())) {
if (!queue.enqueue(*current_thread)) {
// The WaitQueue was already requested to wake someone when
// nobody was waiting. So return right away as we shouldn't
// be waiting
@ -876,6 +887,7 @@ Thread::BlockResult Thread::wait_on(WaitQueue& queue, const char* reason, timeva
return BlockResult::NotBlocked;
}
current_thread->m_wait_queue = &queue;
did_unlock = unlock_process_if_locked();
if (lock)
@ -885,7 +897,6 @@ Thread::BlockResult Thread::wait_on(WaitQueue& queue, const char* reason, timeva
if (timeout) {
timer_id = TimerQueue::the().add_timer(*timeout, [&]() {
ScopedSpinLock sched_lock(g_scheduler_lock);
wake_from_queue();
});
}
@ -921,7 +932,12 @@ Thread::BlockResult Thread::wait_on(WaitQueue& queue, const char* reason, timeva
// scheduler lock, which is held when we insert into the queue
ScopedSpinLock sched_lock(g_scheduler_lock);
if (m_wait_queue_node.is_in_list())
// m_wait_queue should have been cleared either by the timeout
// or by being woken
ASSERT(m_wait_queue == nullptr);
// If our thread was still in the queue, we timed out
if (queue.dequeue(*current_thread))
result = BlockResult::InterruptedByTimeout;
// Make sure we cancel the timer if woke normally.
@ -940,6 +956,7 @@ void Thread::wake_from_queue()
ScopedSpinLock lock(g_scheduler_lock);
ASSERT(state() == State::Queued);
m_wait_reason = nullptr;
m_wait_queue = nullptr;
if (this != Thread::current())
set_state(State::Runnable);
else