From b919789db24cbeb323a694989ca784c43fff9acc Mon Sep 17 00:00:00 2001
From: Tom <tomut@yahoo.com>
Date: Tue, 13 Jul 2021 11:44:30 -0600
Subject: [PATCH] Kernel: Kill user mode threads that are marked to die

Threads that don't make syscalls still need to be killed, and we can
do that at any time we want so long the thread is in user mode and
not somehow blocked (e.g. page fault).
---
 Kernel/Scheduler.cpp | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Kernel/Scheduler.cpp b/Kernel/Scheduler.cpp
index da69b27cd7..ef3e702aca 100644
--- a/Kernel/Scheduler.cpp
+++ b/Kernel/Scheduler.cpp
@@ -443,6 +443,16 @@ void Scheduler::timer_tick(const RegisterState& regs)
         return; // TODO: This prevents scheduling on other CPUs!
 #endif
 
+    if (current_thread->previous_mode() == Thread::PreviousMode::UserMode && current_thread->should_die() && !current_thread->is_blocked()) {
+        dbgln_if(SCHEDULER_DEBUG, "Scheduler[{}]: Terminating user mode thread {}", Processor::id(), *current_thread);
+        {
+            ScopedSpinLock scheduler_lock(g_scheduler_lock);
+            current_thread->set_state(Thread::Dying);
+        }
+        VERIFY(!Processor::current().in_critical());
+        Processor::current().invoke_scheduler_async();
+        return;
+    }
     if (current_thread->tick())
         return;