Config: Add locking for config changed callbacks

Different threads are adding and calling callbacks, so this should have
some locking. This is both to ensure thread safety when accessing
`s_callbacks` and to ensure that there won't be situations where a
callback gets called after it's removed.

`s_callback_guards` is also accessed from multiple threads and has
therefore been made atomic.

1 files changed, 6 insertions, 1 deletions

diff --git a/Source/Core/Common/Config/Config.cpp b/Source/Core/Common/Config/Config.cpp
index b1e591ddac..b5aefc0e9d 100644
--- a/Source/Core/Common/Config/Config.cpp
+++ b/Source/Core/Common/Config/Config.cpp
@@ -20,10 +20,11 @@ using Layers = std::map<LayerType, std::shared_ptr<Layer>>;
 static Layers s_layers;
 static std::vector<std::pair<ConfigChangedCallbackID, ConfigChangedCallback>> s_callbacks;
 static size_t s_next_callback_id = 0;
-static u32 s_callback_guards = 0;
+static std::atomic<u32> s_callback_guards = 0;
 static std::atomic<u64> s_config_version = 0;
 
 static std::shared_mutex s_layers_rw_lock;
+static std::mutex s_callbacks_lock;
 
 using ReadLock = std::shared_lock<std::shared_mutex>;
 using WriteLock = std::unique_lock<std::shared_mutex>;
@@ -69,6 +70,7 @@ void RemoveLayer(LayerType layer)
 
 ConfigChangedCallbackID AddConfigChangedCallback(ConfigChangedCallback func)
 {
+  std::lock_guard lock(s_callbacks_lock);
   const ConfigChangedCallbackID callback_id{s_next_callback_id};
   ++s_next_callback_id;
   s_callbacks.emplace_back(std::make_pair(callback_id, std::move(func)));
@@ -77,6 +79,7 @@ ConfigChangedCallbackID AddConfigChangedCallback(ConfigChangedCallback func)
 
 void RemoveConfigChangedCallback(ConfigChangedCallbackID callback_id)
 {
+  std::lock_guard lock(s_callbacks_lock);
   for (auto it = s_callbacks.begin(); it != s_callbacks.end(); ++it)
   {
     if (it->first == callback_id)
@@ -97,6 +100,8 @@ void OnConfigChanged()
   if (s_callback_guards)
     return;
 
+  std::lock_guard lock(s_callbacks_lock);
+
   for (const auto& callback : s_callbacks)
     callback.second();
 }