md/dm-vdo/wait-queue.c

15  * vdo_waitq_enqueue_waiter() - Add a waiter to the tail end of a waitq.
16  * @waitq: The vdo_wait_queue to which to add the waiter.
17  * @waiter: The waiter to add to the waitq.
19  * The waiter must not already be waiting in a waitq.
21 void vdo_waitq_enqueue_waiter(struct vdo_wait_queue *waitq, struct vdo_waiter *waiter)
23 	BUG_ON(waiter->next_waiter != NULL);
28 		 * initial waiter.
30 		waiter->next_waiter = waiter;
32 		/* Splice the new waiter in at the end of the waitq. */
33 		waiter->next_waiter = waitq->last_waiter->next_waiter;
34 		waitq->last_waiter->next_waiter = waiter;
37 	/* In both cases, the waiter we added to the ring becomes the last waiter. */
38 	waitq->last_waiter = waiter;
75  * @callback: The function to call to notify each waiter, or NULL to invoke the callback field
76  *            registered in each waiter.
101  * vdo_waitq_get_first_waiter() - Return the waiter that is at the head end of a waitq.
102  * @waitq: The vdo_wait_queue from which to get the first waiter.
104  * Return: The first (oldest) waiter in the waitq, or NULL if the waitq is empty.
138 		struct vdo_waiter *waiter = vdo_waitq_dequeue_waiter(&iteration_waitq);
140 		vdo_waitq_enqueue_waiter((waiter_match(waiter, match_context) ?
141 					  matched_waitq : waitq), waiter);
146  * vdo_waitq_dequeue_waiter() - Remove the first (oldest) waiter from a waitq.
149  * The caller will be responsible for waking the waiter by continuing its
152  * Return: The first (oldest) waiter in the waitq, or NULL if the waitq is empty.
167 		 * The waitq has multiple waiters, so splice the first waiter out
173 	/* The waiter is no longer in a waitq. */
182  * @waitq: The vdo_wait_queue containing the waiter to notify.
183  * @callback: The function to call to notify the waiter, or NULL to invoke the callback field
184  *            registered in the waiter.
190  * Return: true if there was a waiter in the waitq.
195 	struct vdo_waiter *waiter = vdo_waitq_dequeue_waiter(waitq);
197 	if (waiter == NULL)
201 		callback = waiter->callback;
202 	callback(waiter, context);