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alistair23-linux/net/tipc/link.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

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/*
* net/tipc/link.h: Include file for TIPC link code
*
* Copyright (c) 1995-2006, Ericsson AB
* Copyright (c) 2004-2005, 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_LINK_H
#define _TIPC_LINK_H
#include "msg.h"
#include "node.h"
/*
* Link reassembly status codes
*/
#define LINK_REASM_ERROR -1
#define LINK_REASM_COMPLETE 1
/*
* Out-of-range value for link sequence numbers
*/
#define INVALID_LINK_SEQ 0x10000
/*
* Link states
*/
#define WORKING_WORKING 560810u
#define WORKING_UNKNOWN 560811u
#define RESET_UNKNOWN 560812u
#define RESET_RESET 560813u
/*
* Starting value for maximum packet size negotiation on unicast links
* (unless bearer MTU is less)
*/
#define MAX_PKT_DEFAULT 1500
struct tipc_stats {
u32 sent_info; /* used in counting # sent packets */
u32 recv_info; /* used in counting # recv'd packets */
u32 sent_states;
u32 recv_states;
u32 sent_probes;
u32 recv_probes;
u32 sent_nacks;
u32 recv_nacks;
u32 sent_acks;
u32 sent_bundled;
u32 sent_bundles;
u32 recv_bundled;
u32 recv_bundles;
u32 retransmitted;
u32 sent_fragmented;
u32 sent_fragments;
u32 recv_fragmented;
u32 recv_fragments;
u32 link_congs; /* # port sends blocked by congestion */
u32 deferred_recv;
u32 duplicates;
u32 max_queue_sz; /* send queue size high water mark */
u32 accu_queue_sz; /* used for send queue size profiling */
u32 queue_sz_counts; /* used for send queue size profiling */
u32 msg_length_counts; /* used for message length profiling */
u32 msg_lengths_total; /* used for message length profiling */
u32 msg_length_profile[7]; /* used for msg. length profiling */
};
/**
* struct tipc_link - TIPC link data structure
* @addr: network address of link's peer node
* @name: link name character string
* @media_addr: media address to use when sending messages over link
* @timer: link timer
* @owner: pointer to peer node
* @link_list: adjacent links in bearer's list of links
* @started: indicates if link has been started
* @checkpoint: reference point for triggering link continuity checking
* @peer_session: link session # being used by peer end of link
* @peer_bearer_id: bearer id used by link's peer endpoint
* @b_ptr: pointer to bearer used by link
* @tolerance: minimum link continuity loss needed to reset link [in ms]
* @continuity_interval: link continuity testing interval [in ms]
* @abort_limit: # of unacknowledged continuity probes needed to reset link
* @state: current state of link FSM
* @blocked: indicates if link has been administratively blocked
* @fsm_msg_cnt: # of protocol messages link FSM has sent in current state
* @proto_msg: template for control messages generated by link
* @pmsg: convenience pointer to "proto_msg" field
* @priority: current link priority
* @queue_limit: outbound message queue congestion thresholds (indexed by user)
* @exp_msg_count: # of tunnelled messages expected during link changeover
* @reset_checkpoint: seq # of last acknowledged message at time of link reset
* @max_pkt: current maximum packet size for this link
* @max_pkt_target: desired maximum packet size for this link
* @max_pkt_probes: # of probes based on current (max_pkt, max_pkt_target)
* @out_queue_size: # of messages in outbound message queue
* @first_out: ptr to first outbound message in queue
* @last_out: ptr to last outbound message in queue
* @next_out_no: next sequence number to use for outbound messages
* @last_retransmitted: sequence number of most recently retransmitted message
* @stale_count: # of identical retransmit requests made by peer
* @next_in_no: next sequence number to expect for inbound messages
* @deferred_inqueue_sz: # of messages in inbound message queue
* @oldest_deferred_in: ptr to first inbound message in queue
* @newest_deferred_in: ptr to last inbound message in queue
* @unacked_window: # of inbound messages rx'd without ack'ing back to peer
* @proto_msg_queue: ptr to (single) outbound control message
* @retransm_queue_size: number of messages to retransmit
* @retransm_queue_head: sequence number of first message to retransmit
* @next_out: ptr to first unsent outbound message in queue
* @waiting_ports: linked list of ports waiting for link congestion to abate
* @long_msg_seq_no: next identifier to use for outbound fragmented messages
* @reasm_head: list head of partially reassembled inbound message fragments
* @reasm_tail: last fragment received
* @stats: collects statistics regarding link activity
*/
struct tipc_link {
u32 addr;
char name[TIPC_MAX_LINK_NAME];
struct tipc_media_addr media_addr;
struct timer_list timer;
struct tipc_node *owner;
struct list_head link_list;
/* Management and link supervision data */
int started;
u32 checkpoint;
u32 peer_session;
u32 peer_bearer_id;
struct tipc_bearer *b_ptr;
u32 tolerance;
u32 continuity_interval;
u32 abort_limit;
int state;
int blocked;
u32 fsm_msg_cnt;
struct {
unchar hdr[INT_H_SIZE];
unchar body[TIPC_MAX_IF_NAME];
} proto_msg;
struct tipc_msg *pmsg;
u32 priority;
u32 queue_limit[15]; /* queue_limit[0]==window limit */
/* Changeover */
u32 exp_msg_count;
u32 reset_checkpoint;
/* Max packet negotiation */
u32 max_pkt;
u32 max_pkt_target;
u32 max_pkt_probes;
/* Sending */
u32 out_queue_size;
struct sk_buff *first_out;
struct sk_buff *last_out;
u32 next_out_no;
u32 last_retransmitted;
u32 stale_count;
/* Reception */
u32 next_in_no;
u32 deferred_inqueue_sz;
struct sk_buff *oldest_deferred_in;
struct sk_buff *newest_deferred_in;
u32 unacked_window;
/* Congestion handling */
struct sk_buff *proto_msg_queue;
u32 retransm_queue_size;
u32 retransm_queue_head;
struct sk_buff *next_out;
struct list_head waiting_ports;
/* Fragmentation/reassembly */
u32 long_msg_seq_no;
struct sk_buff *reasm_head;
struct sk_buff *reasm_tail;
/* Statistics */
struct tipc_stats stats;
};
struct tipc_port;
struct tipc_link *tipc_link_create(struct tipc_node *n_ptr,
struct tipc_bearer *b_ptr,
const struct tipc_media_addr *media_addr);
void tipc_link_delete(struct tipc_link *l_ptr);
void tipc_link_changeover(struct tipc_link *l_ptr);
void tipc_link_send_duplicate(struct tipc_link *l_ptr, struct tipc_link *dest);
void tipc_link_reset_fragments(struct tipc_link *l_ptr);
int tipc_link_is_up(struct tipc_link *l_ptr);
int tipc_link_is_active(struct tipc_link *l_ptr);
u32 tipc_link_push_packet(struct tipc_link *l_ptr);
void tipc_link_stop(struct tipc_link *l_ptr);
struct sk_buff *tipc_link_cmd_config(const void *req_tlv_area, int req_tlv_space, u16 cmd);
struct sk_buff *tipc_link_cmd_show_stats(const void *req_tlv_area, int req_tlv_space);
struct sk_buff *tipc_link_cmd_reset_stats(const void *req_tlv_area, int req_tlv_space);
void tipc_link_reset(struct tipc_link *l_ptr);
int tipc_link_send(struct sk_buff *buf, u32 dest, u32 selector);
void tipc_link_send_names(struct list_head *message_list, u32 dest);
int tipc_link_send_buf(struct tipc_link *l_ptr, struct sk_buff *buf);
u32 tipc_link_get_max_pkt(u32 dest, u32 selector);
int tipc_link_send_sections_fast(struct tipc_port *sender,
struct iovec const *msg_sect,
unsigned int len, u32 destnode);
void tipc_link_recv_bundle(struct sk_buff *buf);
int tipc_link_recv_fragment(struct sk_buff **reasm_head,
struct sk_buff **reasm_tail,
struct sk_buff **fbuf);
void tipc_link_send_proto_msg(struct tipc_link *l_ptr, u32 msg_typ, int prob,
u32 gap, u32 tolerance, u32 priority,
u32 acked_mtu);
void tipc_link_push_queue(struct tipc_link *l_ptr);
u32 tipc_link_defer_pkt(struct sk_buff **head, struct sk_buff **tail,
struct sk_buff *buf);
void tipc_link_wakeup_ports(struct tipc_link *l_ptr, int all);
void tipc_link_set_queue_limits(struct tipc_link *l_ptr, u32 window);
void tipc_link_retransmit(struct tipc_link *l_ptr,
struct sk_buff *start, u32 retransmits);
/*
* Link sequence number manipulation routines (uses modulo 2**16 arithmetic)
*/
static inline u32 buf_seqno(struct sk_buff *buf)
{
return msg_seqno(buf_msg(buf));
}
static inline u32 mod(u32 x)
{
return x & 0xffffu;
}
static inline int between(u32 lower, u32 upper, u32 n)
{
if ((lower < n) && (n < upper))
return 1;
if ((upper < lower) && ((n > lower) || (n < upper)))
return 1;
return 0;
}
static inline int less_eq(u32 left, u32 right)
{
return mod(right - left) < 32768u;
}
static inline int less(u32 left, u32 right)
{
return less_eq(left, right) && (mod(right) != mod(left));
}
static inline u32 lesser(u32 left, u32 right)
{
return less_eq(left, right) ? left : right;
}
/*
* Link status checking routines
*/
static inline int link_working_working(struct tipc_link *l_ptr)
{
return l_ptr->state == WORKING_WORKING;
}
static inline int link_working_unknown(struct tipc_link *l_ptr)
{
return l_ptr->state == WORKING_UNKNOWN;
}
static inline int link_reset_unknown(struct tipc_link *l_ptr)
{
return l_ptr->state == RESET_UNKNOWN;
}
static inline int link_reset_reset(struct tipc_link *l_ptr)
{
return l_ptr->state == RESET_RESET;
}
static inline int link_blocked(struct tipc_link *l_ptr)
{
return l_ptr->exp_msg_count || l_ptr->blocked;
}
static inline int link_congested(struct tipc_link *l_ptr)
{
return l_ptr->out_queue_size >= l_ptr->queue_limit[0];
}
#endif
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