more cleanup

Author: SchrodingerZhu

libc/src/__support/threads/callonce.h

@@ -23,20 +23,14 @@
 #endif
 
 namespace LIBC_NAMESPACE_DECL {
-
-// Common definitions
-namespace callonce_impl {
-template <class CallOnceCallback>
-[[gnu::noinline]] int callonce_slowpath(CallOnceFlag *flag,
-                                        CallOnceCallback callback);
-} // namespace callonce_impl
-
 template <class CallOnceCallback>
 LIBC_INLINE int callonce(CallOnceFlag *flag, CallOnceCallback callback) {
   if (LIBC_LIKELY(callonce_impl::callonce_fastpath(flag)))
     return 0;
 
-  return callonce_impl::callonce_slowpath(flag, callback);
+  return callonce_impl::callonce_slowpath(flag, &callback, [](void *arg) {
+    (*static_cast<CallOnceCallback *>(arg))();
+  });
 }
 } // namespace LIBC_NAMESPACE_DECL
 

libc/src/__support/threads/linux/callonce.h

@@ -27,9 +27,8 @@ LIBC_INLINE bool callonce_fastpath(CallOnceFlag *flag) {
   return flag->load(cpp::MemoryOrder::RELAXED) == FINISH;
 }
 
-template <class CallOnceCallback>
-[[gnu::noinline]] int callonce_slowpath(CallOnceFlag *flag,
-                                        CallOnceCallback callback) {
+[[gnu::cold, gnu::noinline]] LIBC_INLINE int
+callonce_slowpath(CallOnceFlag *flag, void *payload, void (*callback)(void *)) {
 
   auto *futex_word = reinterpret_cast<Futex *>(flag);
 
@@ -38,7 +37,7 @@ template <class CallOnceCallback>
   // The call_once call can return only after the called function |func|
   // returns. So, we use futexes to synchronize calls with the same flag value.
   if (futex_word->compare_exchange_strong(not_called, START)) {
-    callback();
+    callback(payload);
     auto status = futex_word->exchange(FINISH);
     if (status == WAITING)
       futex_word->notify_all();