77ba89c5cf
Add the priority-sorted list (plist) implementation. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
118 lines
2.8 KiB
C
118 lines
2.8 KiB
C
/*
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* lib/plist.c
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*
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* Descending-priority-sorted double-linked list
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*
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* (C) 2002-2003 Intel Corp
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* Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>.
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*
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* 2001-2005 (c) MontaVista Software, Inc.
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* Daniel Walker <dwalker@mvista.com>
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*
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* (C) 2005 Thomas Gleixner <tglx@linutronix.de>
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*
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* Simplifications of the original code by
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* Oleg Nesterov <oleg@tv-sign.ru>
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*
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* Licensed under the FSF's GNU Public License v2 or later.
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*
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* Based on simple lists (include/linux/list.h).
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*
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* This file contains the add / del functions which are considered to
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* be too large to inline. See include/linux/plist.h for further
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* information.
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*/
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#include <linux/plist.h>
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#include <linux/spinlock.h>
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#ifdef CONFIG_DEBUG_PI_LIST
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static void plist_check_prev_next(struct list_head *t, struct list_head *p,
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struct list_head *n)
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{
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if (n->prev != p || p->next != n) {
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printk("top: %p, n: %p, p: %p\n", t, t->next, t->prev);
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printk("prev: %p, n: %p, p: %p\n", p, p->next, p->prev);
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printk("next: %p, n: %p, p: %p\n", n, n->next, n->prev);
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WARN_ON(1);
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}
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}
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static void plist_check_list(struct list_head *top)
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{
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struct list_head *prev = top, *next = top->next;
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plist_check_prev_next(top, prev, next);
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while (next != top) {
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prev = next;
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next = prev->next;
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plist_check_prev_next(top, prev, next);
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}
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}
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static void plist_check_head(struct plist_head *head)
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{
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WARN_ON(!head->lock);
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if (head->lock)
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WARN_ON_SMP(!spin_is_locked(head->lock));
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plist_check_list(&head->prio_list);
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plist_check_list(&head->node_list);
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}
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#else
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# define plist_check_head(h) do { } while (0)
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#endif
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/**
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* plist_add - add @node to @head
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*
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* @node: &struct plist_node pointer
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* @head: &struct plist_head pointer
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*/
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void plist_add(struct plist_node *node, struct plist_head *head)
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{
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struct plist_node *iter;
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plist_check_head(head);
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WARN_ON(!plist_node_empty(node));
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list_for_each_entry(iter, &head->prio_list, plist.prio_list) {
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if (node->prio < iter->prio)
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goto lt_prio;
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else if (node->prio == iter->prio) {
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iter = list_entry(iter->plist.prio_list.next,
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struct plist_node, plist.prio_list);
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goto eq_prio;
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}
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}
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lt_prio:
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list_add_tail(&node->plist.prio_list, &iter->plist.prio_list);
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eq_prio:
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list_add_tail(&node->plist.node_list, &iter->plist.node_list);
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plist_check_head(head);
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}
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/**
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* plist_del - Remove a @node from plist.
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*
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* @node: &struct plist_node pointer - entry to be removed
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* @head: &struct plist_head pointer - list head
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*/
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void plist_del(struct plist_node *node, struct plist_head *head)
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{
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plist_check_head(head);
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if (!list_empty(&node->plist.prio_list)) {
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struct plist_node *next = plist_first(&node->plist);
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list_move_tail(&next->plist.prio_list, &node->plist.prio_list);
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list_del_init(&node->plist.prio_list);
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}
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list_del_init(&node->plist.node_list);
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plist_check_head(head);
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}
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