From f41e254e357880297486cd5cabf5a9148c1f30dc Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Sun, 10 Aug 2025 15:31:42 +0300
Subject: [PATCH] Kernel: Fix dead lock on process exit

---
 kernel/include/kernel/Process.h |  2 ++
 kernel/kernel/Process.cpp       | 24 +++++++++++++++++++-----
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/kernel/include/kernel/Process.h b/kernel/include/kernel/Process.h
index 318a0b17..b71a92bf 100644
--- a/kernel/include/kernel/Process.h
+++ b/kernel/include/kernel/Process.h
@@ -334,6 +334,8 @@ namespace Kernel
 		BAN::Vector<ChildExitStatus> m_child_exit_statuses;
 		ThreadBlocker m_child_exit_blocker;
 
+		BAN::Atomic<bool> m_is_exiting { false };
+
 		bool m_has_called_exec { false };
 
 		BAN::UniqPtr<PageTable> m_page_table;
diff --git a/kernel/kernel/Process.cpp b/kernel/kernel/Process.cpp
index f62914d7..6e360abb 100644
--- a/kernel/kernel/Process.cpp
+++ b/kernel/kernel/Process.cpp
@@ -257,6 +257,16 @@ namespace Kernel
 
 	void Process::exit(int status, int signal)
 	{
+		bool expected = false;
+		if (!m_is_exiting.compare_exchange(expected, true))
+		{
+			Thread::current().on_exit();
+			ASSERT_NOT_REACHED();
+		}
+
+		const auto state = Processor::get_interrupt_state();
+		Processor::set_interrupt_state(InterruptState::Enabled);
+
 		if (m_parent)
 		{
 			Process* parent_process = nullptr;
@@ -294,13 +304,18 @@ namespace Kernel
 			}
 		}
 
-		for (size_t i = 0; i < m_threads.size(); i++)
 		{
-			if (m_threads[i] == &Thread::current())
-				continue;
-			m_threads[i]->add_signal(SIGKILL);
+			LockGuard _(m_process_lock);
+			for (auto* thread : m_threads)
+				if (thread != &Thread::current())
+					ASSERT(thread->add_signal(SIGKILL));
 		}
 
+		while (m_threads.size() > 1)
+			Processor::yield();
+
+		Processor::set_interrupt_state(state);
+
 		Thread::current().on_exit();
 
 		ASSERT_NOT_REACHED();
@@ -507,7 +522,6 @@ namespace Kernel
 	BAN::ErrorOr<long> Process::sys_exit(int status)
 	{
 		ASSERT(this == &Process::current());
-		LockGuard _(m_process_lock);
 		exit(status, 0);
 		ASSERT_NOT_REACHED();
 	}