Kernel: Make the Jails' internal design a lot more sane

This is done with 2 major steps:
1. Remove JailManagement singleton and use a structure that resembles
    what we have with the Process object. This is required later for the
    second step in this commit, but on its own, is a major change that
    removes this clunky singleton that had no real usage by itself.
2. Use IntrusiveLists to keep references to Process objects in the same
    Jail so it will be much more straightforward to iterate on this kind
    of objects when needed. Previously we locked the entire Process list
    and we did a simple pointer comparison to check if the checked
    Process we iterate on is in the same Jail or not, which required
    taking multiple Spinlocks in a very clumsy and heavyweight way.

1 files changed, 17 insertions, 7 deletions

diff --git a/Kernel/Jail.h b/Kernel/Jail.h
index bfbc6c833a..355c15c4ab 100644
--- a/Kernel/Jail.h
+++ b/Kernel/Jail.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Liav A. <liavalb@hotmail.co.il>
+ * Copyright (c) 2022-2023, Liav A. <liavalb@hotmail.co.il>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -9,6 +9,7 @@
 #include <AK/DistinctNumeric.h>
 #include <AK/Error.h>
 #include <AK/IntrusiveList.h>
+#include <AK/IntrusiveListRelaxedConst.h>
 #include <AK/OwnPtr.h>
 #include <AK/RefPtr.h>
 #include <AK/Try.h>
@@ -16,19 +17,21 @@
 #include <Kernel/KString.h>
 #include <Kernel/Library/LockRefPtr.h>
 #include <Kernel/Locking/SpinlockProtected.h>
-#include <Kernel/Process.h>
 
 namespace Kernel {
 
-class JailManagement;
+class ProcessList;
 
 AK_TYPEDEF_DISTINCT_ORDERED_ID(u64, JailIndex);
 
 class Jail : public RefCounted<Jail> {
-    friend class JailManagement;
 
 public:
-    static ErrorOr<NonnullLockRefPtr<Jail>> create(Badge<JailManagement>, NonnullOwnPtr<KString>, JailIndex);
+    NonnullRefPtr<ProcessList> process_list();
+
+    static LockRefPtr<Jail> find_by_index(JailIndex);
+    static ErrorOr<NonnullLockRefPtr<Jail>> create(NonnullOwnPtr<KString> name);
+    static ErrorOr<void> for_each_when_process_is_not_jailed(Function<ErrorOr<void>(Jail const&)> callback);
 
     StringView name() const { return m_name->view(); }
     JailIndex index() const { return m_index; }
@@ -37,12 +40,19 @@ public:
     SpinlockProtected<size_t, LockRank::None>& attach_count() { return m_attach_count; }
 
 private:
-    Jail(NonnullOwnPtr<KString>, JailIndex);
+    Jail(NonnullOwnPtr<KString>, JailIndex, NonnullRefPtr<ProcessList>);
 
     NonnullOwnPtr<KString> m_name;
     JailIndex const m_index;
 
-    IntrusiveListNode<Jail, NonnullLockRefPtr<Jail>> m_jail_list_node;
+    IntrusiveListNode<Jail, NonnullLockRefPtr<Jail>> m_list_node;
+
+public:
+    using List = IntrusiveListRelaxedConst<&Jail::m_list_node>;
+
+private:
+    NonnullRefPtr<ProcessList> m_process_list;
+
     SpinlockProtected<size_t, LockRank::None> m_attach_count { 0 };
 };