/* * Lock-less NULL terminated single linked list * * The basic atomic operation of this list is cmpxchg on long.  On * architectures that don't have NMI-safe cmpxchg implementation, the * list can NOT be used in NMI handlers.  So code that uses the list in * an NMI handler should depend on CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG. * * Copyright 2010,2011 Intel Corp. *   Author: Huang Ying <ying.huang@intel.com> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License version * 2 as published by the Free Software Foundation; * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */#include <linux/kernel.h>#include <linux/export.h>#include <linux/interrupt.h>#include <linux/llist.h>  /** * llist_add_batch - add several linked entries in batch * @new_first:	first entry in batch to be added * @new_last:	last entry in batch to be added * @head:	the head for your lock-less list * * Return whether list is empty before adding. */bool llist_add_batch(struct llist_node *new_first, struct llist_node *new_last,		     struct llist_head *head){	struct llist_node *first; 	do {		new_last->next = first = ACCESS_ONCE(head->first);	} while (cmpxchg(&head->first, first, new_first) != first); 	return !first;}EXPORT_SYMBOL_GPL(llist_add_batch); /** * llist_del_first - delete the first entry of lock-less list * @head:	the head for your lock-less list * * If list is empty, return NULL, otherwise, return the first entry * deleted, this is the newest added one. * * Only one llist_del_first user can be used simultaneously with * multiple llist_add users without lock.  Because otherwise * llist_del_first, llist_add, llist_add (or llist_del_all, llist_add, * llist_add) sequence in another user may change @head->first->next, * but keep @head->first.  If multiple consumers are needed, please * use llist_del_all or use lock between consumers. */struct llist_node *llist_del_first(struct llist_head *head){	struct llist_node *entry, *old_entry, *next; 	entry = head->first;	for (;;) {		if (entry == NULL)			return NULL;		old_entry = entry;		next = entry->next;		entry = cmpxchg(&head->first, old_entry, next);		if (entry == old_entry)			break;	} 	return entry;}EXPORT_SYMBOL_GPL(llist_del_first); /** * llist_reverse_order - reverse order of a llist chain * @head:	first item of the list to be reversed * * Reverse the order of a chain of llist entries and return the * new first entry. */struct llist_node *llist_reverse_order(struct llist_node *head){	struct llist_node *new_head = NULL; 	while (head) {		struct llist_node *tmp = head;		head = head->next;		tmp->next = new_head;		new_head = tmp;	} 	return new_head;}EXPORT_SYMBOL_GPL(llist_reverse_order);