From 7e691f96e1e1d881ea698280868be75814e7f33d Mon Sep 17 00:00:00 2001
From: Brian Gianforcaro <bgianf@serenityos.org>
Date: Thu, 3 Jun 2021 03:21:04 -0700
Subject: [PATCH] Kernel: Switch ProcessGroup to IntrusiveList from
 InlineLinkedList

---
 Kernel/Process.cpp      |  2 +-
 Kernel/ProcessGroup.cpp |  6 +++---
 Kernel/ProcessGroup.h   | 16 +++++++---------
 3 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
index d55fbac717cc33..8e1003e9ab040a 100644
--- a/Kernel/Process.cpp
+++ b/Kernel/Process.cpp
@@ -62,7 +62,7 @@ UNMAP_AFTER_INIT void Process::initialize()
 
     next_pid.store(0, AK::MemoryOrder::memory_order_release);
     g_processes = new InlineLinkedList<Process>;
-    g_process_groups = new InlineLinkedList<ProcessGroup>;
+    g_process_groups = new ProcessGroup::List();
     g_hostname = new String("courage");
     g_hostname_lock = new Lock;
 
diff --git a/Kernel/ProcessGroup.cpp b/Kernel/ProcessGroup.cpp
index 3a92151e518fc3..85a08aa3967b64 100644
--- a/Kernel/ProcessGroup.cpp
+++ b/Kernel/ProcessGroup.cpp
@@ -9,12 +9,12 @@
 namespace Kernel {
 
 RecursiveSpinLock g_process_groups_lock;
-InlineLinkedList<ProcessGroup>* g_process_groups;
+ProcessGroup::List* g_process_groups;
 
 ProcessGroup::~ProcessGroup()
 {
     ScopedSpinLock lock(g_process_groups_lock);
-    g_process_groups->remove(this);
+    g_process_groups->remove(*this);
 }
 
 RefPtr<ProcessGroup> ProcessGroup::create(ProcessGroupID pgid)
@@ -22,7 +22,7 @@ RefPtr<ProcessGroup> ProcessGroup::create(ProcessGroupID pgid)
     auto process_group = adopt_ref_if_nonnull(new ProcessGroup(pgid));
     if (process_group) {
         ScopedSpinLock lock(g_process_groups_lock);
-        g_process_groups->prepend(process_group);
+        g_process_groups->prepend(*process_group);
     }
 
     return process_group;
diff --git a/Kernel/ProcessGroup.h b/Kernel/ProcessGroup.h
index 8ae5f295f5bc02..0be93ff5c43f19 100644
--- a/Kernel/ProcessGroup.h
+++ b/Kernel/ProcessGroup.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/InlineLinkedList.h>
+#include <AK/IntrusiveList.h>
 #include <AK/RefCounted.h>
 #include <AK/Weakable.h>
 #include <Kernel/Lock.h>
@@ -17,14 +17,11 @@ namespace Kernel {
 
 class ProcessGroup
     : public RefCounted<ProcessGroup>
-    , public Weakable<ProcessGroup>
-    , public InlineLinkedListNode<ProcessGroup> {
+    , public Weakable<ProcessGroup> {
 
     AK_MAKE_NONMOVABLE(ProcessGroup);
     AK_MAKE_NONCOPYABLE(ProcessGroup);
 
-    friend InlineLinkedListNode<ProcessGroup>;
-
 public:
     ~ProcessGroup();
 
@@ -40,13 +37,14 @@ class ProcessGroup
     {
     }
 
-    ProcessGroup* m_prev { nullptr };
-    ProcessGroup* m_next { nullptr };
-
+    IntrusiveListNode<ProcessGroup> m_list_node;
     ProcessGroupID m_pgid;
+
+public:
+    using List = IntrusiveList<ProcessGroup, RawPtr<ProcessGroup>, &ProcessGroup::m_list_node>;
 };
 
-extern InlineLinkedList<ProcessGroup>* g_process_groups;
+extern ProcessGroup::List* g_process_groups;
 extern RecursiveSpinLock g_process_groups_lock;
 
 }