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7a54d4a99d
Completely redesigns broadcast link ACK and NACK mechanisms to prevent spurious retransmit requests in dual LAN networks, and to prevent the broadcast link from stalling due to the failure of a receiving node to acknowledge receiving a broadcast message or request its retransmission. Note: These changes only impact the timing of when ACK and NACK messages are sent, and not the basic broadcast link protocol itself, so inter- operability with nodes using the "classic" algorithms is maintained. The revised algorithms are as follows: 1) An explicit ACK message is still sent after receiving 16 in-sequence messages, and implicit ACK information continues to be carried in other unicast link message headers (including link state messages). However, the timing of explicit ACKs is now based on the receiving node's absolute network address rather than its relative network address to ensure that the failure of another node does not delay the ACK beyond its 16 message target. 2) A NACK message is now typically sent only when a message gap persists for two consecutive incoming link state messages; this ensures that a suspected gap is not confirmed until both LANs in a dual LAN network have had an opportunity to deliver the message, thereby preventing spurious NACKs. A NACK message can also be generated by the arrival of a single link state message, if the deferred queue is so big that the current message gap cannot be the result of "normal" mis-ordering due to the use of dual LANs (or one LAN using a bonded interface). Since link state messages typically arrive at different nodes at different times the problem of multiple nodes issuing identical NACKs simultaneously is inherently avoided. 3) Nodes continue to "peek" at NACK messages sent by other nodes. If another node requests retransmission of a message gap suspected (but not yet confirmed) by the peeking node, the peeking node forgets about the gap and does not generate a duplicate retransmit request. (If the peeking node subsequently fails to receive the lost message, later link state messages will cause it to rediscover and confirm the gap and send another NACK.) 4) Message gap "equality" is now determined by the start of the gap only. This is sufficient to deal with the most common cases of message loss, and eliminates the need for complex end of gap computations. 5) A peeking node no longer tries to determine whether it should send a complementary NACK, since the most common cases of message loss don't require it to be sent. Consequently, the node no longer examines the "broadcast tag" field of a NACK message when peeking. Signed-off-by: Allan Stephens <allan.stephens@windriver.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
143 lines
5.6 KiB
C
143 lines
5.6 KiB
C
/*
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* net/tipc/node.h: Include file for TIPC node management routines
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*
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* Copyright (c) 2000-2006, Ericsson AB
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* Copyright (c) 2005, 2010-2011, Wind River Systems
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the names of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* Alternatively, this software may be distributed under the terms of the
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* GNU General Public License ("GPL") version 2 as published by the Free
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* Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _TIPC_NODE_H
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#define _TIPC_NODE_H
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#include "node_subscr.h"
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#include "addr.h"
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#include "net.h"
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#include "bearer.h"
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/* Flags used to block (re)establishment of contact with a neighboring node */
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#define WAIT_PEER_DOWN 0x0001 /* wait to see that peer's links are down */
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#define WAIT_NAMES_GONE 0x0002 /* wait for peer's publications to be purged */
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#define WAIT_NODE_DOWN 0x0004 /* wait until peer node is declared down */
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/**
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* struct tipc_node - TIPC node structure
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* @addr: network address of node
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* @lock: spinlock governing access to structure
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* @hash: links to adjacent nodes in unsorted hash chain
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* @list: links to adjacent nodes in sorted list of cluster's nodes
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* @nsub: list of "node down" subscriptions monitoring node
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* @active_links: pointers to active links to node
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* @links: pointers to all links to node
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* @working_links: number of working links to node (both active and standby)
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* @block_setup: bit mask of conditions preventing link establishment to node
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* @link_cnt: number of links to node
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* @permit_changeover: non-zero if node has redundant links to this system
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* @bclink: broadcast-related info
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* @supportable: non-zero if node supports TIPC b'cast link capability
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* @supported: non-zero if node supports TIPC b'cast capability
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* @acked: sequence # of last outbound b'cast message acknowledged by node
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* @last_in: sequence # of last in-sequence b'cast message received from node
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* @last_sent: sequence # of last b'cast message sent by node
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* @oos_state: state tracker for handling OOS b'cast messages
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* @deferred_size: number of OOS b'cast messages in deferred queue
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* @deferred_head: oldest OOS b'cast message received from node
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* @deferred_tail: newest OOS b'cast message received from node
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* @defragm: list of partially reassembled b'cast message fragments from node
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*/
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struct tipc_node {
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u32 addr;
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spinlock_t lock;
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struct hlist_node hash;
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struct list_head list;
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struct list_head nsub;
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struct tipc_link *active_links[2];
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struct tipc_link *links[MAX_BEARERS];
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int link_cnt;
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int working_links;
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int block_setup;
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int permit_changeover;
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struct {
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u8 supportable;
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u8 supported;
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u32 acked;
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u32 last_in;
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u32 last_sent;
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u32 oos_state;
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u32 deferred_size;
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struct sk_buff *deferred_head;
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struct sk_buff *deferred_tail;
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struct sk_buff *defragm;
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} bclink;
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};
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#define NODE_HTABLE_SIZE 512
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extern struct list_head tipc_node_list;
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/*
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* A trivial power-of-two bitmask technique is used for speed, since this
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* operation is done for every incoming TIPC packet. The number of hash table
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* entries has been chosen so that no hash chain exceeds 8 nodes and will
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* usually be much smaller (typically only a single node).
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*/
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static inline unsigned int tipc_hashfn(u32 addr)
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{
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return addr & (NODE_HTABLE_SIZE - 1);
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}
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extern u32 tipc_own_tag;
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struct tipc_node *tipc_node_find(u32 addr);
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struct tipc_node *tipc_node_create(u32 addr);
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void tipc_node_delete(struct tipc_node *n_ptr);
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void tipc_node_attach_link(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
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void tipc_node_detach_link(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
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void tipc_node_link_down(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
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void tipc_node_link_up(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
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int tipc_node_active_links(struct tipc_node *n_ptr);
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int tipc_node_redundant_links(struct tipc_node *n_ptr);
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int tipc_node_is_up(struct tipc_node *n_ptr);
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struct sk_buff *tipc_node_get_links(const void *req_tlv_area, int req_tlv_space);
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struct sk_buff *tipc_node_get_nodes(const void *req_tlv_area, int req_tlv_space);
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static inline void tipc_node_lock(struct tipc_node *n_ptr)
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{
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spin_lock_bh(&n_ptr->lock);
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}
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static inline void tipc_node_unlock(struct tipc_node *n_ptr)
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{
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spin_unlock_bh(&n_ptr->lock);
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}
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#endif
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