Kernel: Threads are deleted sooner and cleaner

We now delete threads when
    1. it is marked as Terminated and is the current thread
    2. it tries to start execution in Terminated state

This allows us to never have thread executing in Terminated state

kernel/arch/x86_64/IDT.cpp

@@ -201,13 +201,11 @@ namespace IDT
 			Kernel::panic("Unhandled exception");
 		}
 
-		// Don't continue exection when terminated
+		ASSERT(Kernel::Thread::current().state() != Kernel::Thread::State::Terminated);
-		if (Kernel::Thread::current().state() == Kernel::Thread::State::Terminated)
+
-			Kernel::Scheduler::get().execute_current_thread();
-		
 		if (from_userspace)
 		{
-			ASSERT(Kernel::Thread::current().state() != Kernel::Thread::State::Terminating);
+			ASSERT(Kernel::Thread::current().state() == Kernel::Thread::State::Executing);
 			Kernel::Thread::current().load_sse();
 		}
 	}
@@ -243,13 +241,11 @@ namespace IDT
 
 		Kernel::Scheduler::get().reschedule_if_idling();
 
-		// Don't continue exection when terminated
+		ASSERT(Kernel::Thread::current().state() != Kernel::Thread::State::Terminated);
-		if (Kernel::Thread::current().state() == Kernel::Thread::State::Terminated)
-			Kernel::Scheduler::get().execute_current_thread();
 
 		if (from_userspace)
 		{
-			ASSERT(Kernel::Thread::current().state() != Kernel::Thread::State::Terminating);
+			ASSERT(Kernel::Thread::current().state() == Kernel::Thread::State::Executing);
 			Kernel::Thread::current().load_sse();
 		}
 	}

kernel/kernel/Syscall.cpp

@@ -177,11 +177,7 @@ namespace Kernel
 
 		asm volatile("cli");
 
-		// Don't continue exection when terminated
+		ASSERT(Kernel::Thread::current().state() == Kernel::Thread::State::Executing);
-		if (Kernel::Thread::current().state() == Kernel::Thread::State::Terminated)
-			Kernel::Scheduler::get().execute_current_thread();
-
-		ASSERT(Kernel::Thread::current().state() != Kernel::Thread::State::Terminating);
 		Thread::current().load_sse();
 
 		if (ret.is_error())

kernel/kernel/Thread.cpp

@@ -31,6 +31,9 @@ namespace Kernel
 	{
 		CriticalScope _;
 
+		// FIXME: this should not be a requirement
+		ASSERT(&thread == &Thread::current());
+
 		if (m_thread.state() == State::Executing || m_thread.m_terminate_blockers > 0)
 		{
 			m_thread.m_terminate_blockers++;
@@ -38,8 +41,11 @@ namespace Kernel
 		}
 
 		if (m_thread.state() == State::Terminating && m_thread.m_terminate_blockers == 0)
+		{
 			m_thread.m_state = State::Terminated;
-				
+			Scheduler::get().execute_current_thread();
+		}
+
 		while (true)
 			Scheduler::get().reschedule();
 	}
@@ -54,17 +60,29 @@ namespace Kernel
 			return;
 
 		if (m_thread.state() == State::Terminating && m_thread.m_terminate_blockers == 0)
+		{
 			m_thread.m_state = State::Terminated;
+			Scheduler::get().execute_current_thread();
+		}
 
-		while (true)
+		ASSERT_NOT_REACHED();
-			Scheduler::get().reschedule();
 	}
 
 	void Thread::set_terminating()
 	{
 		CriticalScope _;
-		m_state = m_terminate_blockers == 0 ? State::Terminated : State::Terminating;
+		if (m_terminate_blockers == 0)
-		Scheduler::get().unblock_thread(tid());
+		{
+			m_state = State::Terminated;
+			if (this == &Thread::current())
+				Scheduler::get().execute_current_thread();
+		}
+		else
+		{
+			m_state = State::Terminating;
+			if (this == &Thread::current())
+				Scheduler::get().unblock_thread(tid());
+		}
 	}
 
 	static pid_t s_next_tid = 1;