1 // SPDX-License-Identifier: GPL-2.0-only
6 #include "wait-queue.h"
8 #include <linux/device-mapper.h>
12 #include "status-codes.h"
15  * vdo_waitq_enqueue_waiter() - Add a waiter to the tail end of a waitq.
23 	BUG_ON(waiter->next_waiter != NULL);  in vdo_waitq_enqueue_waiter()
25 	if (waitq->last_waiter == NULL) {  in vdo_waitq_enqueue_waiter()
27 		 * The waitq is empty, so form the initial circular list by self-linking the  in vdo_waitq_enqueue_waiter()
30 		waiter->next_waiter = waiter;  in vdo_waitq_enqueue_waiter()
33 		waiter->next_waiter = waitq->last_waiter->next_waiter;  in vdo_waitq_enqueue_waiter()
34 		waitq->last_waiter->next_waiter = waiter;  in vdo_waitq_enqueue_waiter()
38 	waitq->last_waiter = waiter;  in vdo_waitq_enqueue_waiter()
39 	waitq->length += 1;  in vdo_waitq_enqueue_waiter()
43  * vdo_waitq_transfer_all_waiters() - Transfer all waiters from one waitq to
57 		 * Both are non-empty. Splice the two circular lists together  in vdo_waitq_transfer_all_waiters()
60 		struct vdo_waiter *from_head = from_waitq->last_waiter->next_waiter;  in vdo_waitq_transfer_all_waiters()
61 		struct vdo_waiter *to_head = to_waitq->last_waiter->next_waiter;  in vdo_waitq_transfer_all_waiters()
63 		to_waitq->last_waiter->next_waiter = from_head;  in vdo_waitq_transfer_all_waiters()
64 		from_waitq->last_waiter->next_waiter = to_head;  in vdo_waitq_transfer_all_waiters()
67 	to_waitq->last_waiter = from_waitq->last_waiter;  in vdo_waitq_transfer_all_waiters()
68 	to_waitq->length += from_waitq->length;  in vdo_waitq_transfer_all_waiters()
73  * vdo_waitq_notify_all_waiters() - Notify all the entries waiting in a waitq.
95 	/* Drain the copied waitq, invoking the callback on every entry. */  in vdo_waitq_notify_all_waiters()
101  * vdo_waitq_get_first_waiter() - Return the waiter that is at the head end of a waitq.
108 	struct vdo_waiter *last_waiter = waitq->last_waiter;  in vdo_waitq_get_first_waiter()
115 	/* The waitq is circular, so the last entry links to the head of the waitq. */  in vdo_waitq_get_first_waiter()
116 	return last_waiter->next_waiter;  in vdo_waitq_get_first_waiter()
120  * vdo_waitq_dequeue_matching_waiters() - Remove all waiters that match based on the specified
121  *                                        matching method and append them to a vdo_wait_queue.
123  * @waiter_match: The method to determine matching.
124  * @match_context: Contextual info for the match method.
146  * vdo_waitq_dequeue_waiter() - Remove the first (oldest) waiter from a waitq.
147  * @waitq: The vdo_wait_queue from which to remove the first entry.
157 	struct vdo_waiter *last_waiter = waitq->last_waiter;  in vdo_waitq_dequeue_waiter()
163 		/* The waitq has a single entry, so empty it by nulling the tail. */  in vdo_waitq_dequeue_waiter()
164 		waitq->last_waiter = NULL;  in vdo_waitq_dequeue_waiter()
170 		last_waiter->next_waiter = first_waiter->next_waiter;  in vdo_waitq_dequeue_waiter()
174 	first_waiter->next_waiter = NULL;  in vdo_waitq_dequeue_waiter()
175 	waitq->length -= 1;  in vdo_waitq_dequeue_waiter()
181  * vdo_waitq_notify_next_waiter() - Notify the next entry waiting in a waitq.
187  * Notifies the next entry waiting in a waitq to continue execution by invoking a callback function
201 		callback = waiter->callback;  in vdo_waitq_notify_next_waiter()