tcp_io: place write_monitor=0 before queue_resume_callback to prevent busy-loop when waiter_defer=1

lib/tcp_io.c

@@ -386,11 +386,11 @@ static void write_cb(socket_t sock, void* arg) {
     if (flush_write_buf(tc)) return;
     if (!tc->write_buf) {
         DEBUG_TRACE(DEBUG_CATEGORY_SOCKET, "tcp_io: write_cb flushed fd=%d wmon=%d (resume WQ cb)", (int)tc->sock, tc->write_monitor);
-        queue_resume_callback(tc->write_queue);
-        if (tc->write_queue->waiter_defer && tc->write_monitor) {
+        if (tc->write_queue->waiter_defer) {
             uasync_set_socket_write(tc->ua, tc->socket_id, 0);
             tc->write_monitor = 0;
         }
+        queue_resume_callback(tc->write_queue);
     }
 }