| 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->rawlock && !head->spinlock); |
| 58 | if (head->rawlock) |
| 59 | WARN_ON_SMP(!raw_spin_is_locked(head->rawlock)); |
| 60 | if (head->spinlock) |
| 61 | WARN_ON_SMP(!spin_is_locked(head->spinlock)); |
| 62 | plist_check_list(&head->prio_list); |
| 63 | plist_check_list(&head->node_list); |
| 64 | } |
| 65 | |
| 66 | #else |
| 67 | # define plist_check_head(h) do { } while (0) |
| 68 | #endif |
| 69 | |
| 70 | /** |
| 71 | * plist_add - add @node to @head |
| 72 | * |
| 73 | * @node: &struct plist_node pointer |
| 74 | * @head: &struct plist_head pointer |
| 75 | */ |
| 76 | void plist_add(struct plist_node *node, struct plist_head *head) |
| 77 | { |
| 78 | struct plist_node *iter; |
| 79 | |
| 80 | plist_check_head(head); |
| 81 | WARN_ON(!plist_node_empty(node)); |
| 82 | |
| 83 | list_for_each_entry(iter, &head->prio_list, plist.prio_list) { |
| 84 | if (node->prio < iter->prio) |
| 85 | goto lt_prio; |
| 86 | else if (node->prio == iter->prio) { |
| 87 | iter = list_entry(iter->plist.prio_list.next, |
| 88 | struct plist_node, plist.prio_list); |
| 89 | goto eq_prio; |
| 90 | } |
| 91 | } |
| 92 | |
| 93 | lt_prio: |
| 94 | list_add_tail(&node->plist.prio_list, &iter->plist.prio_list); |
| 95 | eq_prio: |
| 96 | list_add_tail(&node->plist.node_list, &iter->plist.node_list); |
| 97 | |
| 98 | plist_check_head(head); |
| 99 | } |
| 100 | |
| 101 | /** |
| 102 | * plist_del - Remove a @node from plist. |
| 103 | * |
| 104 | * @node: &struct plist_node pointer - entry to be removed |
| 105 | * @head: &struct plist_head pointer - list head |
| 106 | */ |
| 107 | void plist_del(struct plist_node *node, struct plist_head *head) |
| 108 | { |
| 109 | plist_check_head(head); |
| 110 | |
| 111 | if (!list_empty(&node->plist.prio_list)) { |
| 112 | struct plist_node *next = plist_first(&node->plist); |
| 113 | |
| 114 | list_move_tail(&next->plist.prio_list, &node->plist.prio_list); |
| 115 | list_del_init(&node->plist.prio_list); |
| 116 | } |
| 117 | |
| 118 | list_del_init(&node->plist.node_list); |
| 119 | |
| 120 | plist_check_head(head); |
| 121 | } |