23 	 * queue->newest and queue->oldest are never null.  in vdo_make_funnel_queue()
27 	queue->oldest = &queue->stub;  in vdo_make_funnel_queue()
45 	struct funnel_queue_entry *oldest = queue->oldest;  in get_oldest()  local
46 	struct funnel_queue_entry *next = READ_ONCE(oldest->next);  in get_oldest()
48 	if (oldest == &queue->stub) {  in get_oldest()
50 		 * When the oldest entry is the stub and it has no successor, the queue is  in get_oldest()
59 		oldest = next;  in get_oldest()
60 		queue->oldest = oldest;  in get_oldest()
61 		next = READ_ONCE(oldest->next);  in get_oldest()
71 		if (oldest != newest) {  in get_oldest()
86 		next = READ_ONCE(oldest->next);  in get_oldest()
96 	return oldest;  in get_oldest()
100  * Poll a queue, removing the oldest entry if the queue is not empty. This function must only be
105 	struct funnel_queue_entry *oldest = get_oldest(queue);  in vdo_funnel_queue_poll()  local
107 	if (oldest == NULL)  in vdo_funnel_queue_poll()
108 		return oldest;  in vdo_funnel_queue_poll()
111 	 * Dequeue the oldest entry and return it. Only one consumer thread may call this function,  in vdo_funnel_queue_poll()
112 	 * so no locking, atomic operations, or fences are needed; queue->oldest is owned by the  in vdo_funnel_queue_poll()
113 	 * consumer and oldest->next is never used by a producer thread after it is swung from NULL  in vdo_funnel_queue_poll()
116 	queue->oldest = READ_ONCE(oldest->next);  in vdo_funnel_queue_poll()
119 	 * fetched the entry pointer we stored in "queue->oldest", this also ensures that on entry  in vdo_funnel_queue_poll()
124 	 * If "oldest" is a very light-weight work item, we'll be looking for the next one very  in vdo_funnel_queue_poll()
127 	uds_prefetch_address(queue->oldest, true);  in vdo_funnel_queue_poll()
128 	WRITE_ONCE(oldest->next, NULL);  in vdo_funnel_queue_poll()
129 	return oldest;  in vdo_funnel_queue_poll()
151 	 * Oldest is not the stub, so there's another entry, though if next is NULL we can't  in vdo_is_funnel_queue_idle()
154 	if (queue->oldest != &queue->stub)  in vdo_is_funnel_queue_idle()
158 	 * Oldest is the stub, but newest has been updated by _put(); either there's another,  in vdo_is_funnel_queue_idle()