include/linux/plist.h

1 /* SPDX-License-Identifier: GPL-2.0-or-later */
3  * Descending-priority-sorted double-linked list
5  * (C) 2002-2003 Intel Corp
6  * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>.
8  * 2001-2005 (c) MontaVista Software, Inc.
14  * Oleg Nesterov <oleg@tv-sign.ru>
18  * This is a priority-sorted list of nodes; each node has a
21  * Addition is O(K), removal is O(1), change of priority of a node is
22  * O(K) and K is the number of RT priority levels used in the system.
23  * (1 <= K <= 99)
27  *  - The tier 1 list is the prio_list, different priority nodes.
29  *  - The tier 2 list is the node_list, serialized nodes.
37  *       ||------------------------------------|
38  *       ||->|pl|<->|pl|<--------------->|pl|<-|
39  *       |   |10|   |21|   |21|   |21|   |40|   (prio)
42  * |->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<->|nl|<-|
43  * |-------------------------------------------|
83  * PLIST_HEAD_INIT - static struct plist_head initializer
92  * PLIST_HEAD - declare and init plist_head
99  * PLIST_NODE_INIT - static struct plist_node initializer
111  * plist_head_init - dynamic struct plist_head initializer
117 	INIT_LIST_HEAD(&head->node_list);  in plist_head_init()
121  * plist_node_init - Dynamic struct plist_node initializer
127 	node->prio = prio;  in plist_node_init()
128 	INIT_LIST_HEAD(&node->prio_list);  in plist_node_init()
129 	INIT_LIST_HEAD(&node->node_list);  in plist_node_init()
138  * plist_for_each - iterate over the plist
143 	 list_for_each_entry(pos, &(head)->node_list, node_list)
146  * plist_for_each_continue - continue iteration over the plist
153 	 list_for_each_entry_continue(pos, &(head)->node_list, node_list)
156  * plist_for_each_safe - iterate safely over a plist of given type
164 	 list_for_each_entry_safe(pos, n, &(head)->node_list, node_list)
167  * plist_for_each_entry	- iterate over list of given type
173 	 list_for_each_entry(pos, &(head)->node_list, mem.node_list)
176  * plist_for_each_entry_continue - continue iteration over list of given type
185 	list_for_each_entry_continue(pos, &(head)->node_list, m.node_list)
188  * plist_for_each_entry_safe - iterate safely over list of given type
197 	list_for_each_entry_safe(pos, n, &(head)->node_list, m.node_list)
200  * plist_head_empty - return !0 if a plist_head is empty
205 	return list_empty(&head->node_list);  in plist_head_empty()
209  * plist_node_empty - return !0 if plist_node is not on a list
214 	return list_empty(&node->node_list);  in plist_node_empty()
220  * plist_first_entry - get the struct for the first entry
237  * plist_last_entry - get the struct for the last entry
254  * plist_next - get the next entry in list
261  * plist_prev - get the prev entry in list
268  * plist_first - return the first node (and thus, highest priority)
275 	return list_entry(head->node_list.next,  in plist_first()
280  * plist_last - return the last node (and thus, lowest priority)
287 	return list_entry(head->node_list.prev,  in plist_last()