linux/net/tipc/node.h
Erik Hugne 40ba3cdf54 tipc: message reassembly using fragment chain
When the first fragment of a long data data message is received on a link, a
reassembly buffer large enough to hold the data from this and all subsequent
fragments of the message is allocated. The payload of each new fragment is
copied into this buffer upon arrival. When the last fragment is received, the
reassembled message is delivered upwards to the port/socket layer.

Not only is this an inefficient approach, but it may also cause bursts of
reassembly failures in low memory situations. since we may fail to allocate
the necessary large buffer in the first place. Furthermore, after 100 subsequent
such failures the link will be reset, something that in reality aggravates the
situation.

To remedy this problem, this patch introduces a different approach. Instead of
allocating a big reassembly buffer, we now append the arriving fragments
to a reassembly chain on the link, and deliver the whole chain up to the
socket layer once the last fragment has been received. This is safe because
the retransmission layer of a TIPC link always delivers packets in strict
uninterrupted order, to the reassembly layer as to all other upper layers.
Hence there can never be more than one fragment chain pending reassembly at
any given time in a link, and we can trust (but still verify) that the
fragments will be chained up in the correct order.

Signed-off-by: Erik Hugne <erik.hugne@ericsson.com>
Reviewed-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-11-07 18:30:11 -05:00

134 lines
5.3 KiB
C

/*
* net/tipc/node.h: Include file for TIPC node management routines
*
* Copyright (c) 2000-2006, Ericsson AB
* Copyright (c) 2005, 2010-2011, 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_NODE_H
#define _TIPC_NODE_H
#include "node_subscr.h"
#include "addr.h"
#include "net.h"
#include "bearer.h"
/*
* Out-of-range value for node signature
*/
#define INVALID_NODE_SIG 0x10000
/* Flags used to block (re)establishment of contact with a neighboring node */
#define WAIT_PEER_DOWN 0x0001 /* wait to see that peer's links are down */
#define WAIT_NAMES_GONE 0x0002 /* wait for peer's publications to be purged */
#define WAIT_NODE_DOWN 0x0004 /* wait until peer node is declared down */
/**
* struct tipc_node - TIPC node structure
* @addr: network address of node
* @lock: spinlock governing access to structure
* @hash: links to adjacent nodes in unsorted hash chain
* @list: links to adjacent nodes in sorted list of cluster's nodes
* @nsub: list of "node down" subscriptions monitoring node
* @active_links: pointers to active links to node
* @links: pointers to all links to node
* @working_links: number of working links to node (both active and standby)
* @block_setup: bit mask of conditions preventing link establishment to node
* @link_cnt: number of links to node
* @permit_changeover: non-zero if node has redundant links to this system
* @signature: node instance identifier
* @bclink: broadcast-related info
* @acked: sequence # of last outbound b'cast message acknowledged by node
* @last_in: sequence # of last in-sequence b'cast message received from node
* @last_sent: sequence # of last b'cast message sent by node
* @oos_state: state tracker for handling OOS b'cast messages
* @deferred_size: number of OOS b'cast messages in deferred queue
* @deferred_head: oldest OOS b'cast message received from node
* @deferred_tail: newest OOS b'cast message received from node
* @reasm_head: broadcast reassembly queue head from node
* @reasm_tail: last broadcast fragment received from node
* @recv_permitted: true if node is allowed to receive b'cast messages
*/
struct tipc_node {
u32 addr;
spinlock_t lock;
struct hlist_node hash;
struct list_head list;
struct list_head nsub;
struct tipc_link *active_links[2];
struct tipc_link *links[MAX_BEARERS];
int link_cnt;
int working_links;
int block_setup;
int permit_changeover;
u32 signature;
struct {
u32 acked;
u32 last_in;
u32 last_sent;
u32 oos_state;
u32 deferred_size;
struct sk_buff *deferred_head;
struct sk_buff *deferred_tail;
struct sk_buff *reasm_head;
struct sk_buff *reasm_tail;
bool recv_permitted;
} bclink;
};
extern struct list_head tipc_node_list;
struct tipc_node *tipc_node_find(u32 addr);
struct tipc_node *tipc_node_create(u32 addr);
void tipc_node_delete(struct tipc_node *n_ptr);
void tipc_node_attach_link(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
void tipc_node_detach_link(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
void tipc_node_link_down(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
void tipc_node_link_up(struct tipc_node *n_ptr, struct tipc_link *l_ptr);
int tipc_node_active_links(struct tipc_node *n_ptr);
int tipc_node_redundant_links(struct tipc_node *n_ptr);
int tipc_node_is_up(struct tipc_node *n_ptr);
struct sk_buff *tipc_node_get_links(const void *req_tlv_area, int req_tlv_space);
struct sk_buff *tipc_node_get_nodes(const void *req_tlv_area, int req_tlv_space);
static inline void tipc_node_lock(struct tipc_node *n_ptr)
{
spin_lock_bh(&n_ptr->lock);
}
static inline void tipc_node_unlock(struct tipc_node *n_ptr)
{
spin_unlock_bh(&n_ptr->lock);
}
#endif