Kernel: Switch singletons to use new Singleton class

MemoryManager cannot use the Singleton class because
MemoryManager::initialize is called before the global constructors
are run. That caused the Singleton to be re-initialized, causing
it to create another MemoryManager instance.

Fixes #3226

Kernel/FileSystem/DevPtsFS.cpp

@@ -24,6 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <AK/Singleton.h>
 #include <AK/StringBuilder.h>
 #include <AK/StringView.h>
 #include <Kernel/FileSystem/DevPtsFS.h>
@@ -45,14 +46,10 @@ DevPtsFS::~DevPtsFS()
 {
 }
 
-static HashTable<unsigned>* ptys;
+static AK::Singleton<HashTable<unsigned>> s_ptys;
 
 bool DevPtsFS::initialize()
 {
-    if (ptys == nullptr) {
-        ptys = new HashTable<unsigned>();
-    }
-
     m_root_inode = adopt(*new DevPtsFSInode(*this, 1));
     m_root_inode->m_metadata.inode = { fsid(), 1 };
     m_root_inode->m_metadata.mode = 0040555;
@@ -104,12 +101,12 @@ RefPtr<Inode> DevPtsFS::get_inode(InodeIdentifier inode_id) const
 
 void DevPtsFS::register_slave_pty(SlavePTY& slave_pty)
 {
-    ptys->set(slave_pty.index());
+    s_ptys->set(slave_pty.index());
 }
 
 void DevPtsFS::unregister_slave_pty(SlavePTY& slave_pty)
 {
-    ptys->remove(slave_pty.index());
+    s_ptys->remove(slave_pty.index());
 }
 
 DevPtsFSInode::DevPtsFSInode(DevPtsFS& fs, unsigned index)
@@ -144,7 +141,7 @@ KResult DevPtsFSInode::traverse_as_directory(Function<bool(const FS::DirectoryEn
     callback({ ".", identifier(), 0 });
     callback({ "..", identifier(), 0 });
 
-    for (unsigned pty_index : *ptys) {
+    for (unsigned pty_index : *s_ptys) {
         String name = String::number(pty_index);
         InodeIdentifier identifier = { fsid(), pty_index_to_inode_index(pty_index) };
         callback({ name, identifier, 0 });
@@ -157,7 +154,7 @@ KResultOr<size_t> DevPtsFSInode::directory_entry_count() const
 {
     ASSERT(identifier().index() == 1);
 
-    return 2 + ptys->size();
+    return 2 + s_ptys->size();
 }
 
 RefPtr<Inode> DevPtsFSInode::lookup(StringView name)
@@ -170,7 +167,7 @@ RefPtr<Inode> DevPtsFSInode::lookup(StringView name)
     auto& fs = static_cast<DevPtsFS&>(this->fs());
 
     auto pty_index = name.to_uint();
-    if (pty_index.has_value() && ptys->contains(pty_index.value())) {
+    if (pty_index.has_value() && s_ptys->contains(pty_index.value())) {
         return fs.get_inode({ fsid(), pty_index_to_inode_index(pty_index.value()) });
     }
 

Kernel/FileSystem/FIFO.cpp

@@ -25,6 +25,7 @@
  */
 
 #include <AK/HashTable.h>
+#include <AK/Singleton.h>
 #include <AK/StdLibExtras.h>
 #include <AK/StringView.h>
 #include <Kernel/FileSystem/FIFO.h>
@@ -37,11 +38,10 @@
 
 namespace Kernel {
 
+static AK::Singleton<Lockable<HashTable<FIFO*>>> s_table;
+
 static Lockable<HashTable<FIFO*>>& all_fifos()
 {
-    static Lockable<HashTable<FIFO*>>* s_table;
-    if (!s_table)
-        s_table = new Lockable<HashTable<FIFO*>>;
     return *s_table;
 }
 

Kernel/FileSystem/FileSystem.cpp

@@ -26,6 +26,7 @@
 
 #include <AK/Assertions.h>
 #include <AK/HashMap.h>
+#include <AK/Singleton.h>
 #include <AK/StringBuilder.h>
 #include <AK/StringView.h>
 #include <Kernel/FileSystem/FileSystem.h>
@@ -37,12 +38,10 @@
 namespace Kernel {
 
 static u32 s_lastFileSystemID;
-static HashMap<u32, FS*>* s_fs_map;
+static AK::Singleton<HashMap<u32, FS*>> s_fs_map;
 
 static HashMap<u32, FS*>& all_fses()
 {
-    if (!s_fs_map)
-        s_fs_map = new HashMap<u32, FS*>();
     return *s_fs_map;
 }
 

Kernel/FileSystem/Inode.cpp

@@ -25,6 +25,7 @@
  */
 
 #include <AK/NonnullRefPtrVector.h>
+#include <AK/Singleton.h>
 #include <AK/StringBuilder.h>
 #include <AK/StringView.h>
 #include <Kernel/FileSystem/Custody.h>
@@ -38,15 +39,13 @@
 namespace Kernel {
 
 static SpinLock s_all_inodes_lock;
+static AK::Singleton<InlineLinkedList<Inode>> s_list;
 
 InlineLinkedList<Inode>& Inode::all_with_lock()
 {
     ASSERT(s_all_inodes_lock.is_locked());
 
-    static InlineLinkedList<Inode>* list;
-    if (!list)
-        list = new InlineLinkedList<Inode>;
-    return *list;
+    return *s_list;
 }
 
 void Inode::sync()

Kernel/FileSystem/VirtualFileSystem.cpp

@@ -25,6 +25,7 @@
  */
 
 #include <AK/LexicalPath.h>
+#include <AK/Singleton.h>
 #include <AK/StringBuilder.h>
 #include <Kernel/Devices/BlockDevice.h>
 #include <Kernel/FileSystem/Custody.h>
@@ -40,13 +41,17 @@
 
 namespace Kernel {
 
-static VFS* s_the;
+static AK::Singleton<VFS> s_the;
 static constexpr int symlink_recursion_limit { 5 }; // FIXME: increase?
 static constexpr int root_mount_flags = MS_NODEV | MS_NOSUID | MS_RDONLY;
 
+void VFS::initialize()
+{
+    s_the.ensure_instance();
+}
+
 VFS& VFS::the()
 {
-    ASSERT(s_the);
     return *s_the;
 }
 
@@ -55,7 +60,6 @@ VFS::VFS()
 #ifdef VFS_DEBUG
     klog() << "VFS: Constructing VFS";
 #endif
-    s_the = this;
 }
 
 VFS::~VFS()

Kernel/FileSystem/VirtualFileSystem.h

@@ -78,6 +78,7 @@ public:
         int m_flags;
     };
 
+    static void initialize();
     static VFS& the();
 
     VFS();