When you check available, you might have to do it as a (__atomic_load_n(&sender->realend, __ATOMIC_SEQ_CST) and do __atomic_store_n when setting available. rat

When you check available, you might have to do it as a (__atomic_load_n(&sender->realend, __ATOMIC_SEQ_CST) and do __atomic_store_n when setting available. rather than just a plain load.