Merge git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6
[linux-2.6.git] / lib / plist.c
1 /*
2  * lib/plist.c
3  *
4  * Descending-priority-sorted double-linked list
5  *
6  * (C) 2002-2003 Intel Corp
7  * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>.
8  *
9  * 2001-2005 (c) MontaVista Software, Inc.
10  * Daniel Walker <dwalker@mvista.com>
11  *
12  * (C) 2005 Thomas Gleixner <tglx@linutronix.de>
13  *
14  * Simplifications of the original code by
15  * Oleg Nesterov <oleg@tv-sign.ru>
16  *
17  * Licensed under the FSF's GNU Public License v2 or later.
18  *
19  * Based on simple lists (include/linux/list.h).
20  *
21  * This file contains the add / del functions which are considered to
22  * be too large to inline. See include/linux/plist.h for further
23  * information.
24  */
25
26 #include <linux/plist.h>
27 #include <linux/spinlock.h>
28
29 #ifdef CONFIG_DEBUG_PI_LIST
30
31 static void plist_check_prev_next(struct list_head *t, struct list_head *p,
32                                   struct list_head *n)
33 {
34         WARN(n->prev != p || p->next != n,
35                         "top: %p, n: %p, p: %p\n"
36                         "prev: %p, n: %p, p: %p\n"
37                         "next: %p, n: %p, p: %p\n",
38                          t, t->next, t->prev,
39                         p, p->next, p->prev,
40                         n, n->next, n->prev);
41 }
42
43 static void plist_check_list(struct list_head *top)
44 {
45         struct list_head *prev = top, *next = top->next;
46
47         plist_check_prev_next(top, prev, next);
48         while (next != top) {
49                 prev = next;
50                 next = prev->next;
51                 plist_check_prev_next(top, prev, next);
52         }
53 }
54
55 static void plist_check_head(struct plist_head *head)
56 {
57         WARN_ON(!head->lock);
58         if (head->lock)
59                 WARN_ON_SMP(!spin_is_locked(head->lock));
60         plist_check_list(&head->prio_list);
61         plist_check_list(&head->node_list);
62 }
63
64 #else
65 # define plist_check_head(h)    do { } while (0)
66 #endif
67
68 /**
69  * plist_add - add @node to @head
70  *
71  * @node:       &struct plist_node pointer
72  * @head:       &struct plist_head pointer
73  */
74 void plist_add(struct plist_node *node, struct plist_head *head)
75 {
76         struct plist_node *iter;
77
78         plist_check_head(head);
79         WARN_ON(!plist_node_empty(node));
80
81         list_for_each_entry(iter, &head->prio_list, plist.prio_list) {
82                 if (node->prio < iter->prio)
83                         goto lt_prio;
84                 else if (node->prio == iter->prio) {
85                         iter = list_entry(iter->plist.prio_list.next,
86                                         struct plist_node, plist.prio_list);
87                         goto eq_prio;
88                 }
89         }
90
91 lt_prio:
92         list_add_tail(&node->plist.prio_list, &iter->plist.prio_list);
93 eq_prio:
94         list_add_tail(&node->plist.node_list, &iter->plist.node_list);
95
96         plist_check_head(head);
97 }
98
99 /**
100  * plist_del - Remove a @node from plist.
101  *
102  * @node:       &struct plist_node pointer - entry to be removed
103  * @head:       &struct plist_head pointer - list head
104  */
105 void plist_del(struct plist_node *node, struct plist_head *head)
106 {
107         plist_check_head(head);
108
109         if (!list_empty(&node->plist.prio_list)) {
110                 struct plist_node *next = plist_first(&node->plist);
111
112                 list_move_tail(&next->plist.prio_list, &node->plist.prio_list);
113                 list_del_init(&node->plist.prio_list);
114         }
115
116         list_del_init(&node->plist.node_list);
117
118         plist_check_head(head);
119 }