This is a step in the direction of continuously polling the queue fd on the server side, removing the need for ntsync to notify wineserver before / after waiting on the queue.
For this my plan is to make win32u also notify wineserver to update the queue access time before waiting (through set_queue_mask), if it's been long enough. Then decide that a queue is hung based on whether it is signaled but access time is more than 5s ago (ie: neither get_message nor set_queue_mask are called regularly even though queue is signaled).
On the server side, the queue fd would stop being polling once it gets ready, and win32u would notify wineserver after all the driver events have been processed, to start polling it again, as a separate request from the wait.