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 if (n->prev != p || p->next != n) { 35 printk("top: %p, n: %p, p: %p\n", t, t->next, t->prev); 36 printk("prev: %p, n: %p, p: %p\n", p, p->next, p->prev); 37 printk("next: %p, n: %p, p: %p\n", n, n->next, n->prev); 38 WARN_ON(1); 39 } 40 } 41 42 static void plist_check_list(struct list_head *top) 43 { 44 struct list_head *prev = top, *next = top->next; 45 46 plist_check_prev_next(top, prev, next); 47 while (next != top) { 48 prev = next; 49 next = prev->next; 50 plist_check_prev_next(top, prev, next); 51 } 52 } 53 54 static void plist_check_head(struct plist_head *head) 55 { 56 WARN_ON(!head->lock); 57 if (head->lock) 58 WARN_ON_SMP(!spin_is_locked(head->lock)); 59 plist_check_list(&head->prio_list); 60 plist_check_list(&head->node_list); 61 } 62 63 #else 64 # define plist_check_head(h) do { } while (0) 65 #endif 66 67 /** 68 * plist_add - add @node to @head 69 * 70 * @node: &struct plist_node pointer 71 * @head: &struct plist_head pointer 72 */ 73 void plist_add(struct plist_node *node, struct plist_head *head) 74 { 75 struct plist_node *iter; 76 77 plist_check_head(head); 78 WARN_ON(!plist_node_empty(node)); 79 80 list_for_each_entry(iter, &head->prio_list, plist.prio_list) { 81 if (node->prio < iter->prio) 82 goto lt_prio; 83 else if (node->prio == iter->prio) { 84 iter = list_entry(iter->plist.prio_list.next, 85 struct plist_node, plist.prio_list); 86 goto eq_prio; 87 } 88 } 89 90 lt_prio: 91 list_add_tail(&node->plist.prio_list, &iter->plist.prio_list); 92 eq_prio: 93 list_add_tail(&node->plist.node_list, &iter->plist.node_list); 94 95 plist_check_head(head); 96 } 97 98 /** 99 * plist_del - Remove a @node from plist. 100 * 101 * @node: &struct plist_node pointer - entry to be removed 102 * @head: &struct plist_head pointer - list head 103 */ 104 void plist_del(struct plist_node *node, struct plist_head *head) 105 { 106 plist_check_head(head); 107 108 if (!list_empty(&node->plist.prio_list)) { 109 struct plist_node *next = plist_first(&node->plist); 110 111 list_move_tail(&next->plist.prio_list, &node->plist.prio_list); 112 list_del_init(&node->plist.prio_list); 113 } 114 115 list_del_init(&node->plist.node_list); 116 117 plist_check_head(head); 118 } 119