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Kernel: Move Thread::block<BlockerType>() out of the Thread.h header

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This function is large and unwieldy and forces Thread.h to #include
a bunch of things. The only reason it was in the header is because we
need to instantiate a blocker based on the templated BlockerType.

We actually keep block<BlockerType>() in the header, but move the
bulk of the function body out of line into Thread::block_impl().

To preserve destructor ordering, we add Blocker::finalize() which is
called where we'd previously destroy the Blocker.
This commit is contained in:
Andreas Kling 2022-01-29 12:46:04 +01:00
parent 79ee846f3d
commit f469fb47b8
Notes: sideshowbarker 2024-07-17 20:00:05 +09:00
3 changed files with 138 additions and 118 deletions
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123
Kernel/Thread.h
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@ -300,6 +300,7 @@ public:
virtual const BlockTimeout& override_timeout(const BlockTimeout& timeout) { return timeout; }
virtual bool can_be_interrupted() const { return true; }
virtual bool setup_blocker();
virtual void finalize();
Thread& thread() { return m_thread; }
@ -690,6 +691,7 @@ public:
virtual void was_unblocked(bool) override;
virtual StringView state_string() const override { return "Selecting"sv; }
virtual bool setup_blocker() override;
virtual void finalize() override;
private:
size_t collect_unblocked_flags();
@ -870,125 +872,10 @@ public:
void block(Kernel::Mutex&, SpinlockLocker<Spinlock>&, u32);
template<typename BlockerType, class... Args>
[[nodiscard]] BlockResult block(const BlockTimeout& timeout, Args&&... args)
BlockResult block(BlockTimeout const& timeout, Args&&... args)
{
VERIFY(!Processor::current_in_irq());
VERIFY(this == Thread::current());
ScopedCritical critical;
VERIFY(!Memory::s_mm_lock.is_locked_by_current_processor());
SpinlockLocker block_lock(m_block_lock);
// We need to hold m_block_lock so that nobody can unblock a blocker as soon
// as it is constructed and registered elsewhere
VERIFY(!m_in_block);
TemporaryChange in_block_change(m_in_block, true);
BlockerType blocker(forward<Args>(args)...);
if (!blocker.setup_blocker()) {
blocker.will_unblock_immediately_without_blocking(Blocker::UnblockImmediatelyReason::UnblockConditionAlreadyMet);
return BlockResult::NotBlocked;
}
SpinlockLocker scheduler_lock(g_scheduler_lock);
// Relaxed semantics are fine for timeout_unblocked because we
// synchronize on the spin locks already.
Atomic<bool, AK::MemoryOrder::memory_order_relaxed> timeout_unblocked(false);
bool timer_was_added = false;
switch (state()) {
case Thread::Stopped:
// It's possible that we were requested to be stopped!
break;
case Thread::Running:
VERIFY(m_blocker == nullptr);
break;
default:
VERIFY_NOT_REACHED();
}
m_blocker = &blocker;
if (auto& block_timeout = blocker.override_timeout(timeout); !block_timeout.is_infinite()) {
// Process::kill_all_threads may be called at any time, which will mark all
// threads to die. In that case
timer_was_added = TimerQueue::the().add_timer_without_id(*m_block_timer, block_timeout.clock_id(), block_timeout.absolute_time(), [&]() {
VERIFY(!Processor::current_in_irq());
VERIFY(!g_scheduler_lock.is_locked_by_current_processor());
VERIFY(!m_block_lock.is_locked_by_current_processor());
// NOTE: this may execute on the same or any other processor!
SpinlockLocker scheduler_lock(g_scheduler_lock);
SpinlockLocker block_lock(m_block_lock);
if (m_blocker && !timeout_unblocked.exchange(true))
unblock();
});
if (!timer_was_added) {
// Timeout is already in the past
blocker.will_unblock_immediately_without_blocking(Blocker::UnblockImmediatelyReason::TimeoutInThePast);
m_blocker = nullptr;
return BlockResult::InterruptedByTimeout;
}
}
blocker.begin_blocking({});
set_state(Thread::Blocked);
scheduler_lock.unlock();
block_lock.unlock();
dbgln_if(THREAD_DEBUG, "Thread {} blocking on {} ({}) -->", *this, &blocker, blocker.state_string());
bool did_timeout = false;
u32 lock_count_to_restore = 0;
auto previous_locked = unlock_process_if_locked(lock_count_to_restore);
for (;;) {
// Yield to the scheduler, and wait for us to resume unblocked.
VERIFY(!g_scheduler_lock.is_locked_by_current_processor());
VERIFY(Processor::in_critical());
yield_without_releasing_big_lock();
VERIFY(Processor::in_critical());
SpinlockLocker block_lock2(m_block_lock);
if (m_blocker && !m_blocker->can_be_interrupted() && !m_should_die) {
block_lock2.unlock();
dbgln("Thread should not be unblocking, current state: {}", state_string());
set_state(Thread::Blocked);
continue;
}
// Prevent the timeout from unblocking this thread if it happens to
// be in the process of firing already
did_timeout |= timeout_unblocked.exchange(true);
if (m_blocker) {
// Remove ourselves...
VERIFY(m_blocker == &blocker);
m_blocker = nullptr;
}
dbgln_if(THREAD_DEBUG, "<-- Thread {} unblocked from {} ({})", *this, &blocker, blocker.state_string());
break;
}
if (blocker.was_interrupted_by_signal()) {
SpinlockLocker scheduler_lock(g_scheduler_lock);
SpinlockLocker lock(m_lock);
dispatch_one_pending_signal();
}
// Notify the blocker that we are no longer blocking. It may need
// to clean up now while we're still holding m_lock
auto result = blocker.end_blocking({}, did_timeout); // calls was_unblocked internally
if (timer_was_added && !did_timeout) {
// Cancel the timer while not holding any locks. This allows
// the timer function to complete before we remove it
// (e.g. if it's on another processor)
TimerQueue::the().cancel_timer(*m_block_timer);
}
if (previous_locked != LockMode::Unlocked) {
// NOTE: this may trigger another call to Thread::block(), so
// we need to do this after we're all done and restored m_in_block!
relock_process(previous_locked, lock_count_to_restore);
}
return result;
return block_impl(timeout, blocker);
}
u32 unblock_from_lock(Kernel::Mutex&);
@ -1251,6 +1138,8 @@ public:
private:
Thread(NonnullRefPtr<Process>, NonnullOwnPtr<Memory::Region>, NonnullRefPtr<Timer>, NonnullOwnPtr<KString>);
BlockResult block_impl(BlockTimeout const&, Blocker&);
IntrusiveListNode<Thread> m_process_thread_list_node;
int m_runnable_priority { -1 };