kernel-ark/net/tipc/name_distr.h
Jon Paul Maloy c637c10355 tipc: resolve race problem at unicast message reception
TIPC handles message cardinality and sequencing at the link layer,
before passing messages upwards to the destination sockets. During the
upcall from link to socket no locks are held. It is therefore possible,
and we see it happen occasionally, that messages arriving in different
threads and delivered in sequence still bypass each other before they
reach the destination socket. This must not happen, since it violates
the sequentiality guarantee.

We solve this by adding a new input buffer queue to the link structure.
Arriving messages are added safely to the tail of that queue by the
link, while the head of the queue is consumed, also safely, by the
receiving socket. Sequentiality is secured per socket by only allowing
buffers to be dequeued inside the socket lock. Since there may be multiple
simultaneous readers of the queue, we use a 'filter' parameter to reduce
the risk that they peek the same buffer from the queue, hence also
reducing the risk of contention on the receiving socket locks.

This solves the sequentiality problem, and seems to cause no measurable
performance degradation.

A nice side effect of this change is that lock handling in the functions
tipc_rcv() and tipc_bcast_rcv() now becomes uniform, something that
will enable future simplifications of those functions.

Reviewed-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-05 16:00:02 -08:00

80 lines
3.3 KiB
C

/*
* net/tipc/name_distr.h: Include file for TIPC name distribution code
*
* Copyright (c) 2000-2006, Ericsson AB
* Copyright (c) 2005, Wind River Systems
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the names of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* Alternatively, this software may be distributed under the terms of the
* GNU General Public License ("GPL") version 2 as published by the Free
* Software Foundation.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef _TIPC_NAME_DISTR_H
#define _TIPC_NAME_DISTR_H
#include "name_table.h"
#define ITEM_SIZE sizeof(struct distr_item)
/**
* struct distr_item - publication info distributed to other nodes
* @type: name sequence type
* @lower: name sequence lower bound
* @upper: name sequence upper bound
* @ref: publishing port reference
* @key: publication key
*
* ===> All fields are stored in network byte order. <===
*
* First 3 fields identify (name or) name sequence being published.
* Reference field uniquely identifies port that published name sequence.
* Key field uniquely identifies publication, in the event a port has
* multiple publications of the same name sequence.
*
* Note: There is no field that identifies the publishing node because it is
* the same for all items contained within a publication message.
*/
struct distr_item {
__be32 type;
__be32 lower;
__be32 upper;
__be32 ref;
__be32 key;
};
struct sk_buff *tipc_named_publish(struct net *net, struct publication *publ);
struct sk_buff *tipc_named_withdraw(struct net *net, struct publication *publ);
void named_cluster_distribute(struct net *net, struct sk_buff *buf);
void tipc_named_node_up(struct net *net, u32 dnode);
void tipc_named_rcv(struct net *net, struct sk_buff_head *msg_queue);
void tipc_named_reinit(struct net *net);
void tipc_named_process_backlog(struct net *net);
void tipc_publ_notify(struct net *net, struct list_head *nsub_list, u32 addr);
#endif