Kernel: Use a Lockable<bool> for sysctl booleans as well.

AK/Lock.h

@@ -103,6 +103,12 @@ public:
     Lock& lock() { return m_lock; }
     T& resource() { return m_resource; }
 
+    T lock_and_copy()
+    {
+        LOCKER(m_lock);
+        return m_resource;
+    }
+
 private:
     T m_resource;
     Lock m_lock;

Kernel/ProcFS.cpp

@@ -560,7 +560,11 @@ static ByteBuffer read_sys_bool(InodeIdentifier inode_id)
     auto& custom_data = *static_cast<const SysVariableData*>(inode.custom_data());
     ASSERT(custom_data.type == SysVariableData::Boolean);
     ASSERT(custom_data.address);
-    buffer[0] = *reinterpret_cast<bool*>(custom_data.address) ? '1' : '0';
+    auto* lockable_bool = reinterpret_cast<Lockable<bool>*>(custom_data.address);
+    {
+        LOCKER(lockable_bool->lock());
+        buffer[0] = lockable_bool->resource() ? '1' : '0';
+    }
     buffer[1] = '\n';
     return buffer;
 }
@@ -572,14 +576,17 @@ static ssize_t write_sys_bool(InodeIdentifier inode_id, const ByteBuffer& data)
         return { };
     auto& inode = static_cast<ProcFSInode&>(*inode_ptr);
     ASSERT(inode.custom_data());
-    if (data.size() >= 1 && (data[0] == '0' || data[0] == '1')) {
-        auto& custom_data = *static_cast<const SysVariableData*>(inode.custom_data());
-        ASSERT(custom_data.address);
-        bool new_value = data[0] == '1';
-        *reinterpret_cast<bool*>(custom_data.address) = new_value;
-        if (custom_data.notify_callback)
-            custom_data.notify_callback();
+    if (data.is_empty() || !(data[0] == '0' || data[0] == '1'))
+        return data.size();
+
+    auto& custom_data = *static_cast<const SysVariableData*>(inode.custom_data());
+    auto* lockable_bool = reinterpret_cast<Lockable<bool>*>(custom_data.address);
+    {
+        LOCKER(lockable_bool->lock());
+        lockable_bool->resource() = data[0] == '1';
     }
+    if (custom_data.notify_callback)
+        custom_data.notify_callback();
     return data.size();
 }
 
@@ -618,7 +625,7 @@ static ssize_t write_sys_string(InodeIdentifier inode_id, const ByteBuffer& data
     return data.size();
 }
 
-void ProcFS::add_sys_bool(String&& name, bool* var, Function<void()>&& notify_callback)
+void ProcFS::add_sys_bool(String&& name, Lockable<bool>& var, Function<void()>&& notify_callback)
 {
     InterruptDisabler disabler;
 
@@ -627,7 +634,7 @@ void ProcFS::add_sys_bool(String&& name, bool* var, Function<void()>&& notify_ca
     auto data = make<SysVariableData>();
     data->type = SysVariableData::Boolean;
     data->notify_callback = move(notify_callback);
-    data->address = var;
+    data->address = &var;
     inode->set_custom_data(move(data));
     m_sys_entries.append({ strdup(name.characters()), name.length(), read_sys_bool, write_sys_bool, move(inode) });
 }

Kernel/ProcFS.h

@@ -26,7 +26,7 @@ public:
     virtual RetainPtr<Inode> create_directory(InodeIdentifier parent_id, const String& name, mode_t, int& error) override;
 
     void add_sys_file(String&&, Function<ByteBuffer(ProcFSInode&)>&& read_callback, Function<ssize_t(ProcFSInode&, const ByteBuffer&)>&& write_callback);
-    void add_sys_bool(String&&, bool*, Function<void()>&& notify_callback = nullptr);
+    void add_sys_bool(String&&, Lockable<bool>&, Function<void()>&& notify_callback = nullptr);
     void add_sys_string(String&&, Lockable<String>&, Function<void()>&& notify_callback = nullptr);
 
 private:

WindowServer/WSWindowManager.cpp

@@ -131,6 +131,7 @@ WSWindowManager::WSWindowManager()
     : m_screen(WSScreen::the())
     , m_screen_rect(m_screen.rect())
     , m_lock("WSWindowManager")
+    , m_flash_flush(false)
 {
 #ifndef DEBUG_COUNTERS
     (void)m_compose_count;
@@ -168,7 +169,7 @@ WSWindowManager::WSWindowManager()
         m_wallpaper = GraphicsBitmap::load_from_file(m_wallpaper_path.resource(), m_screen_rect.size());
     }
 
-    ProcFS::the().add_sys_bool("wm_flash_flush", &m_flash_flush);
+    ProcFS::the().add_sys_bool("wm_flash_flush", m_flash_flush);
     ProcFS::the().add_sys_string("wm_wallpaper", m_wallpaper_path, [this] {
         LOCKER(m_wallpaper_path.lock());
         m_wallpaper = GraphicsBitmap::load_from_file(m_wallpaper_path.resource(), m_screen_rect.size());
@@ -441,7 +442,6 @@ void WSWindowManager::compose()
         if (any_window_contains_rect(dirty_rect)) {
             continue;
         }
-        //dbgprintf("Repaint root %d,%d %dx%d\n", dirty_rect.x(), dirty_rect.y(), dirty_rect.width(), dirty_rect.height());
         LOCKER(m_wallpaper_path.lock());
         if (!m_wallpaper)
             m_back_painter->fill_rect(dirty_rect, m_background_color);
@@ -472,7 +472,8 @@ void WSWindowManager::compose()
     }
     draw_cursor();
 
-    if (m_flash_flush) {
+
+    if (m_flash_flush.lock_and_copy()) {
         for (auto& rect : dirty_rects)
             m_front_painter->fill_rect(rect, Color::Yellow);
     }

WindowServer/WSWindowManager.h

@@ -110,6 +110,6 @@ private:
 
     mutable Lock m_lock;
 
-    bool m_flash_flush { false };
+    Lockable<bool> m_flash_flush;
     bool m_buffers_are_flipped { false };
 };