mirror of
https://github.com/torvalds/linux.git
synced 2024-11-17 17:41:44 +00:00
0791a6057c
fix comment typo, per Jan Cc: Christoph Hellwig <hch@lst.de> Cc: Jan Kara <jack@suse.cz> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
106 lines
3.1 KiB
C
106 lines
3.1 KiB
C
/*
|
|
* 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);
|