Kernel: Make thread unblocking O(1)

This is still bit broken. VirtualBox seems to freeze sometimes, but I
could not recreate this on qemu (with and without kvm) or real hardware.

kernel/kernel/ThreadBlocker.cpp

@@ -7,7 +7,7 @@ namespace Kernel
 
 	void ThreadBlocker::block_indefinite()
 	{
-		Processor::scheduler().block_current_thread(this, ~static_cast<uint64_t>(0));
+		Processor::scheduler().block_current_thread(this, static_cast<uint64_t>(-1));
 	}
 
 	void ThreadBlocker::block_with_timeout_ns(uint64_t timeout_ns)
@@ -22,7 +22,71 @@ namespace Kernel
 
 	void ThreadBlocker::unblock()
 	{
-		Processor::scheduler().unblock_threads(this);
+		SchedulerQueue::Node* block_chain;
+
+		{
+			SpinLockGuard _(m_lock);
+			block_chain = m_block_chain;
+			m_block_chain = nullptr;
+		}
+
+		for (auto* node = block_chain; node;)
+		{
+			ASSERT(node->blocked);
+
+			auto* next = node->block_chain_next;
+			node->blocker = nullptr;
+			node->block_chain_next = nullptr;
+			node->block_chain_prev = nullptr;
+			Processor::scheduler().unblock_thread(node);
+			node = next;
+		}
 	}
 
+	void ThreadBlocker::add_thread_to_block_queue(SchedulerQueue::Node* node)
+	{
+		ASSERT(node);
+		ASSERT(node->blocked);
+		ASSERT(node->blocker == nullptr);
+		ASSERT(node->block_chain_prev == nullptr);
+		ASSERT(node->block_chain_next == nullptr);
+
+		SpinLockGuard _(m_lock);
+		node->blocker = this;
+		node->block_chain_prev = nullptr;
+		node->block_chain_next = m_block_chain;
+		if (m_block_chain)
+			m_block_chain->block_chain_prev = node;
+		m_block_chain = node;
+	}
+
+	void ThreadBlocker::remove_blocked_thread(SchedulerQueue::Node* node)
+	{
+		SpinLockGuard _(m_lock);
+
+		ASSERT(node);
+		ASSERT(node->blocked);
+		ASSERT(node->blocker == this);
+
+		if (node == m_block_chain)
+		{
+			ASSERT(node->block_chain_prev == nullptr);
+			m_block_chain = node->block_chain_next;
+			if (m_block_chain)
+				m_block_chain->block_chain_prev = nullptr;
+		}
+		else
+		{
+			ASSERT(node->block_chain_prev);
+			node->block_chain_prev->block_chain_next = node->block_chain_next;
+			if (node->block_chain_next)
+				node->block_chain_next->block_chain_prev = node->block_chain_prev;
+		}
+
+		node->blocker = nullptr;
+		node->block_chain_next = nullptr;
+		node->block_chain_prev = nullptr;
+	}
+
+
 }