linux/net/tipc/discover.c
Allan Stephens 972a77fbf1 tipc: Revise timings used when sending link request messages
Revises the algorithm governing the sending of link request messages
to take into account the number of nodes each bearer is currently in
contact with, and to ensure more rapid rediscovery of neighboring nodes
if a bearer fails and then recovers.

The discovery object now sends requests at least once a second if it
is not in contact with any other nodes, and at least once a minute if
it has at least one neighbor; if contact with the only neighbor is
lost, the object immediately reverts to its initial rapid-fire search
timing to accelerate the rediscovery process.

In addition, the discovery object now stops issuing link request
messages if it is in contact with the only neighboring node it is
configured to communicate with, since further searching is unnecessary.

Signed-off-by: Allan Stephens <Allan.Stephens@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2011-05-10 16:04:02 -04:00

359 lines
10 KiB
C

/*
* net/tipc/discover.c
*
* Copyright (c) 2003-2006, Ericsson AB
* Copyright (c) 2005-2006, 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.
*/
#include "core.h"
#include "link.h"
#include "discover.h"
#define TIPC_LINK_REQ_INIT 125 /* min delay during bearer start up */
#define TIPC_LINK_REQ_FAST 1000 /* max delay if bearer has no links */
#define TIPC_LINK_REQ_SLOW 60000 /* max delay if bearer has links */
#define TIPC_LINK_REQ_INACTIVE 0xffffffff /* indicates no timer in use */
/**
* struct link_req - information about an ongoing link setup request
* @bearer: bearer issuing requests
* @dest: destination address for request messages
* @domain: network domain to which links can be established
* @num_nodes: number of nodes currently discovered (i.e. with an active link)
* @buf: request message to be (repeatedly) sent
* @timer: timer governing period between requests
* @timer_intv: current interval between requests (in ms)
*/
struct link_req {
struct tipc_bearer *bearer;
struct tipc_media_addr dest;
u32 domain;
int num_nodes;
struct sk_buff *buf;
struct timer_list timer;
unsigned int timer_intv;
};
/**
* tipc_disc_init_msg - initialize a link setup message
* @type: message type (request or response)
* @dest_domain: network domain of node(s) which should respond to message
* @b_ptr: ptr to bearer issuing message
*/
static struct sk_buff *tipc_disc_init_msg(u32 type,
u32 dest_domain,
struct tipc_bearer *b_ptr)
{
struct sk_buff *buf = tipc_buf_acquire(INT_H_SIZE);
struct tipc_msg *msg;
if (buf) {
msg = buf_msg(buf);
tipc_msg_init(msg, LINK_CONFIG, type, INT_H_SIZE, dest_domain);
msg_set_non_seq(msg, 1);
msg_set_dest_domain(msg, dest_domain);
msg_set_bc_netid(msg, tipc_net_id);
msg_set_media_addr(msg, &b_ptr->addr);
}
return buf;
}
/**
* disc_dupl_alert - issue node address duplication alert
* @b_ptr: pointer to bearer detecting duplication
* @node_addr: duplicated node address
* @media_addr: media address advertised by duplicated node
*/
static void disc_dupl_alert(struct tipc_bearer *b_ptr, u32 node_addr,
struct tipc_media_addr *media_addr)
{
char node_addr_str[16];
char media_addr_str[64];
struct print_buf pb;
tipc_addr_string_fill(node_addr_str, node_addr);
tipc_printbuf_init(&pb, media_addr_str, sizeof(media_addr_str));
tipc_media_addr_printf(&pb, media_addr);
tipc_printbuf_validate(&pb);
warn("Duplicate %s using %s seen on <%s>\n",
node_addr_str, media_addr_str, b_ptr->name);
}
/**
* tipc_disc_recv_msg - handle incoming link setup message (request or response)
* @buf: buffer containing message
* @b_ptr: bearer that message arrived on
*/
void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr)
{
struct tipc_node *n_ptr;
struct link *link;
struct tipc_media_addr media_addr, *addr;
struct sk_buff *rbuf;
struct tipc_msg *msg = buf_msg(buf);
u32 dest = msg_dest_domain(msg);
u32 orig = msg_prevnode(msg);
u32 net_id = msg_bc_netid(msg);
u32 type = msg_type(msg);
int link_fully_up;
msg_get_media_addr(msg, &media_addr);
buf_discard(buf);
/* Validate discovery message from requesting node */
if (net_id != tipc_net_id)
return;
if (!tipc_addr_domain_valid(dest))
return;
if (!tipc_addr_node_valid(orig))
return;
if (orig == tipc_own_addr) {
if (memcmp(&media_addr, &b_ptr->addr, sizeof(media_addr)))
disc_dupl_alert(b_ptr, tipc_own_addr, &media_addr);
return;
}
if (!tipc_in_scope(dest, tipc_own_addr))
return;
if (!tipc_in_scope(b_ptr->link_req->domain, orig))
return;
/* Locate structure corresponding to requesting node */
n_ptr = tipc_node_find(orig);
if (!n_ptr) {
n_ptr = tipc_node_create(orig);
if (!n_ptr)
return;
}
tipc_node_lock(n_ptr);
/* Don't talk to neighbor during cleanup after last session */
if (n_ptr->cleanup_required) {
tipc_node_unlock(n_ptr);
return;
}
link = n_ptr->links[b_ptr->identity];
/* Create a link endpoint for this bearer, if necessary */
if (!link) {
link = tipc_link_create(n_ptr, b_ptr, &media_addr);
if (!link) {
tipc_node_unlock(n_ptr);
return;
}
}
/*
* Ensure requesting node's media address is correct
*
* If media address doesn't match and the link is working, reject the
* request (must be from a duplicate node).
*
* If media address doesn't match and the link is not working, accept
* the new media address and reset the link to ensure it starts up
* cleanly.
*/
addr = &link->media_addr;
if (memcmp(addr, &media_addr, sizeof(*addr))) {
if (tipc_link_is_up(link) || (!link->started)) {
disc_dupl_alert(b_ptr, orig, &media_addr);
tipc_node_unlock(n_ptr);
return;
}
warn("Resetting link <%s>, peer interface address changed\n",
link->name);
memcpy(addr, &media_addr, sizeof(*addr));
tipc_link_reset(link);
}
/* Accept discovery message & send response, if necessary */
link_fully_up = link_working_working(link);
if ((type == DSC_REQ_MSG) && !link_fully_up && !b_ptr->blocked) {
rbuf = tipc_disc_init_msg(DSC_RESP_MSG, orig, b_ptr);
if (rbuf) {
b_ptr->media->send_msg(rbuf, b_ptr, &media_addr);
buf_discard(rbuf);
}
}
tipc_node_unlock(n_ptr);
}
/**
* disc_update - update frequency of periodic link setup requests
* @req: ptr to link request structure
*
* Reinitiates discovery process if discovery object has no associated nodes
* and is either not currently searching or is searching at a slow rate
*/
static void disc_update(struct link_req *req)
{
if (!req->num_nodes) {
if ((req->timer_intv == TIPC_LINK_REQ_INACTIVE) ||
(req->timer_intv > TIPC_LINK_REQ_FAST)) {
req->timer_intv = TIPC_LINK_REQ_INIT;
k_start_timer(&req->timer, req->timer_intv);
}
}
}
/**
* tipc_disc_add_dest - increment set of discovered nodes
* @req: ptr to link request structure
*/
void tipc_disc_add_dest(struct link_req *req)
{
req->num_nodes++;
}
/**
* tipc_disc_remove_dest - decrement set of discovered nodes
* @req: ptr to link request structure
*/
void tipc_disc_remove_dest(struct link_req *req)
{
req->num_nodes--;
disc_update(req);
}
/**
* disc_send_msg - send link setup request message
* @req: ptr to link request structure
*/
static void disc_send_msg(struct link_req *req)
{
if (!req->bearer->blocked)
tipc_bearer_send(req->bearer, req->buf, &req->dest);
}
/**
* disc_timeout - send a periodic link setup request
* @req: ptr to link request structure
*
* Called whenever a link setup request timer associated with a bearer expires.
*/
static void disc_timeout(struct link_req *req)
{
int max_delay;
spin_lock_bh(&req->bearer->lock);
/* Stop searching if only desired node has been found */
if (tipc_node(req->domain) && req->num_nodes) {
req->timer_intv = TIPC_LINK_REQ_INACTIVE;
goto exit;
}
/*
* Send discovery message, then update discovery timer
*
* Keep doubling time between requests until limit is reached;
* hold at fast polling rate if don't have any associated nodes,
* otherwise hold at slow polling rate
*/
disc_send_msg(req);
req->timer_intv *= 2;
if (req->num_nodes)
max_delay = TIPC_LINK_REQ_SLOW;
else
max_delay = TIPC_LINK_REQ_FAST;
if (req->timer_intv > max_delay)
req->timer_intv = max_delay;
k_start_timer(&req->timer, req->timer_intv);
exit:
spin_unlock_bh(&req->bearer->lock);
}
/**
* tipc_disc_create - create object to send periodic link setup requests
* @b_ptr: ptr to bearer issuing requests
* @dest: destination address for request messages
* @dest_domain: network domain to which links can be established
*
* Returns 0 if successful, otherwise -errno.
*/
int tipc_disc_create(struct tipc_bearer *b_ptr,
struct tipc_media_addr *dest, u32 dest_domain)
{
struct link_req *req;
req = kmalloc(sizeof(*req), GFP_ATOMIC);
if (!req)
return -ENOMEM;
req->buf = tipc_disc_init_msg(DSC_REQ_MSG, dest_domain, b_ptr);
if (!req->buf) {
kfree(req);
return -ENOMSG;
}
memcpy(&req->dest, dest, sizeof(*dest));
req->bearer = b_ptr;
req->domain = dest_domain;
req->num_nodes = 0;
req->timer_intv = TIPC_LINK_REQ_INIT;
k_init_timer(&req->timer, (Handler)disc_timeout, (unsigned long)req);
k_start_timer(&req->timer, req->timer_intv);
b_ptr->link_req = req;
disc_send_msg(req);
return 0;
}
/**
* tipc_disc_delete - destroy object sending periodic link setup requests
* @req: ptr to link request structure
*/
void tipc_disc_delete(struct link_req *req)
{
k_cancel_timer(&req->timer);
k_term_timer(&req->timer);
buf_discard(req->buf);
kfree(req);
}