linux/lib/llist.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * 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 <[email protected]>
 */
#include <linux/kernel.h>
#include <linux/export.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)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * 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)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * llist_del_first_this - delete given entry of lock-less list if it is first
 * @head:	the head for your lock-less list
 * @this:	a list entry.
 *
 * If head of the list is given entry, delete and return %true else
 * return %false.
 *
 * Multiple callers can safely call this concurrently with multiple
 * llist_add() callers, providing all the callers offer a different @this.
 */
bool llist_del_first_this(struct llist_head *head,
			  struct llist_node *this)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * 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)
{ … }
EXPORT_SYMBOL_GPL(…);