linux/net/tipc/node.c
Allan Stephens b4b5610223 tipc: Ensure both nodes recognize loss of contact between them
Enhances TIPC to ensure that a node that loses contact with a
neighboring node does not allow contact to be re-established until
it sees that its peer has also recognized the loss of contact.

Previously, nodes that were connected by two or more links could
encounter a situation in which node A would lose contact with node B
on all of its links, purge its name table of names published by B,
and then fail to repopulate those names once contact with B was restored.
This would happen because B was able to re-establish one or more links
so quickly that it never reached a point where it had no links to A --
meaning that B never saw a loss of contact with A, and consequently
didn't re-publish its names to A.

This problem is now prevented by enhancing the cleanup done by TIPC
following a loss of contact with a neighboring node to ensure that
node A ignores all messages sent by B until it receives a LINK_PROTOCOL
message that indicates B has lost contact with A, thereby preventing
the (re)establishment of links between the nodes. The loss of contact
is recognized when a RESET or ACTIVATE message is received that has
a "redundant link exists" field of 0, indicating that B's sending link
endpoint is in a reset state and that B has no other working links.

Additionally, TIPC now suppresses the sending of (most) link protocol
messages to a neighboring node while it is cleaning up after an earlier
loss of contact with that node. This stops the peer node from prematurely
activating its link endpoint, which would prevent TIPC from later
activating its own end. TIPC still allows outgoing RESET messages to
occur during cleanup, to avoid problems if its own node recognizes
the loss of contact first and tries to notify the peer of the situation.

Finally, TIPC now recognizes an impending loss of contact with a peer node
as soon as it receives a RESET message on a working link that is the
peer's only link to the node, and ensures that the link protocol
suppression mentioned above goes into effect right away -- that is,
even before its own link endpoints have failed. This is necessary to
ensure correct operation when there are redundant links between the nodes,
since otherwise TIPC would send an ACTIVATE message upon receiving a RESET
on its first link and only begin suppressing when a RESET on its second
link was received, instead of initiating suppression with the first RESET
message as it needs to.

Note: The reworked cleanup code also eliminates a check that prevented
a link endpoint's discovery object from responding to incoming messages
while stale name table entries are being purged. This check is now
unnecessary and would have slowed down re-establishment of communication
between the nodes in some situations.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2011-09-17 22:55:03 -04:00

498 lines
14 KiB
C

/*
* net/tipc/node.c: TIPC node management routines
*
* Copyright (c) 2000-2006, 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 "config.h"
#include "node.h"
#include "name_distr.h"
static void node_lost_contact(struct tipc_node *n_ptr);
static void node_established_contact(struct tipc_node *n_ptr);
static DEFINE_SPINLOCK(node_create_lock);
static struct hlist_head node_htable[NODE_HTABLE_SIZE];
LIST_HEAD(tipc_node_list);
static u32 tipc_num_nodes;
static atomic_t tipc_num_links = ATOMIC_INIT(0);
u32 tipc_own_tag;
/**
* tipc_node_find - locate specified node object, if it exists
*/
struct tipc_node *tipc_node_find(u32 addr)
{
struct tipc_node *node;
struct hlist_node *pos;
if (unlikely(!in_own_cluster(addr)))
return NULL;
hlist_for_each_entry(node, pos, &node_htable[tipc_hashfn(addr)], hash) {
if (node->addr == addr)
return node;
}
return NULL;
}
/**
* tipc_node_create - create neighboring node
*
* Currently, this routine is called by neighbor discovery code, which holds
* net_lock for reading only. We must take node_create_lock to ensure a node
* isn't created twice if two different bearers discover the node at the same
* time. (It would be preferable to switch to holding net_lock in write mode,
* but this is a non-trivial change.)
*/
struct tipc_node *tipc_node_create(u32 addr)
{
struct tipc_node *n_ptr, *temp_node;
spin_lock_bh(&node_create_lock);
n_ptr = tipc_node_find(addr);
if (n_ptr) {
spin_unlock_bh(&node_create_lock);
return n_ptr;
}
n_ptr = kzalloc(sizeof(*n_ptr), GFP_ATOMIC);
if (!n_ptr) {
spin_unlock_bh(&node_create_lock);
warn("Node creation failed, no memory\n");
return NULL;
}
n_ptr->addr = addr;
spin_lock_init(&n_ptr->lock);
INIT_HLIST_NODE(&n_ptr->hash);
INIT_LIST_HEAD(&n_ptr->list);
INIT_LIST_HEAD(&n_ptr->nsub);
hlist_add_head(&n_ptr->hash, &node_htable[tipc_hashfn(addr)]);
list_for_each_entry(temp_node, &tipc_node_list, list) {
if (n_ptr->addr < temp_node->addr)
break;
}
list_add_tail(&n_ptr->list, &temp_node->list);
n_ptr->block_setup = WAIT_PEER_DOWN;
tipc_num_nodes++;
spin_unlock_bh(&node_create_lock);
return n_ptr;
}
void tipc_node_delete(struct tipc_node *n_ptr)
{
list_del(&n_ptr->list);
hlist_del(&n_ptr->hash);
kfree(n_ptr);
tipc_num_nodes--;
}
/**
* tipc_node_link_up - handle addition of link
*
* Link becomes active (alone or shared) or standby, depending on its priority.
*/
void tipc_node_link_up(struct tipc_node *n_ptr, struct link *l_ptr)
{
struct link **active = &n_ptr->active_links[0];
n_ptr->working_links++;
info("Established link <%s> on network plane %c\n",
l_ptr->name, l_ptr->b_ptr->net_plane);
if (!active[0]) {
active[0] = active[1] = l_ptr;
node_established_contact(n_ptr);
return;
}
if (l_ptr->priority < active[0]->priority) {
info("New link <%s> becomes standby\n", l_ptr->name);
return;
}
tipc_link_send_duplicate(active[0], l_ptr);
if (l_ptr->priority == active[0]->priority) {
active[0] = l_ptr;
return;
}
info("Old link <%s> becomes standby\n", active[0]->name);
if (active[1] != active[0])
info("Old link <%s> becomes standby\n", active[1]->name);
active[0] = active[1] = l_ptr;
}
/**
* node_select_active_links - select active link
*/
static void node_select_active_links(struct tipc_node *n_ptr)
{
struct link **active = &n_ptr->active_links[0];
u32 i;
u32 highest_prio = 0;
active[0] = active[1] = NULL;
for (i = 0; i < MAX_BEARERS; i++) {
struct link *l_ptr = n_ptr->links[i];
if (!l_ptr || !tipc_link_is_up(l_ptr) ||
(l_ptr->priority < highest_prio))
continue;
if (l_ptr->priority > highest_prio) {
highest_prio = l_ptr->priority;
active[0] = active[1] = l_ptr;
} else {
active[1] = l_ptr;
}
}
}
/**
* tipc_node_link_down - handle loss of link
*/
void tipc_node_link_down(struct tipc_node *n_ptr, struct link *l_ptr)
{
struct link **active;
n_ptr->working_links--;
if (!tipc_link_is_active(l_ptr)) {
info("Lost standby link <%s> on network plane %c\n",
l_ptr->name, l_ptr->b_ptr->net_plane);
return;
}
info("Lost link <%s> on network plane %c\n",
l_ptr->name, l_ptr->b_ptr->net_plane);
active = &n_ptr->active_links[0];
if (active[0] == l_ptr)
active[0] = active[1];
if (active[1] == l_ptr)
active[1] = active[0];
if (active[0] == l_ptr)
node_select_active_links(n_ptr);
if (tipc_node_is_up(n_ptr))
tipc_link_changeover(l_ptr);
else
node_lost_contact(n_ptr);
}
int tipc_node_active_links(struct tipc_node *n_ptr)
{
return n_ptr->active_links[0] != NULL;
}
int tipc_node_redundant_links(struct tipc_node *n_ptr)
{
return n_ptr->working_links > 1;
}
int tipc_node_is_up(struct tipc_node *n_ptr)
{
return tipc_node_active_links(n_ptr);
}
void tipc_node_attach_link(struct tipc_node *n_ptr, struct link *l_ptr)
{
n_ptr->links[l_ptr->b_ptr->identity] = l_ptr;
atomic_inc(&tipc_num_links);
n_ptr->link_cnt++;
}
void tipc_node_detach_link(struct tipc_node *n_ptr, struct link *l_ptr)
{
n_ptr->links[l_ptr->b_ptr->identity] = NULL;
atomic_dec(&tipc_num_links);
n_ptr->link_cnt--;
}
/*
* Routing table management - five cases to handle:
*
* 1: A link towards a zone/cluster external node comes up.
* => Send a multicast message updating routing tables of all
* system nodes within own cluster that the new destination
* can be reached via this node.
* (node.establishedContact()=>cluster.multicastNewRoute())
*
* 2: A link towards a slave node comes up.
* => Send a multicast message updating routing tables of all
* system nodes within own cluster that the new destination
* can be reached via this node.
* (node.establishedContact()=>cluster.multicastNewRoute())
* => Send a message to the slave node about existence
* of all system nodes within cluster:
* (node.establishedContact()=>cluster.sendLocalRoutes())
*
* 3: A new cluster local system node becomes available.
* => Send message(s) to this particular node containing
* information about all cluster external and slave
* nodes which can be reached via this node.
* (node.establishedContact()==>network.sendExternalRoutes())
* (node.establishedContact()==>network.sendSlaveRoutes())
* => Send messages to all directly connected slave nodes
* containing information about the existence of the new node
* (node.establishedContact()=>cluster.multicastNewRoute())
*
* 4: The link towards a zone/cluster external node or slave
* node goes down.
* => Send a multcast message updating routing tables of all
* nodes within cluster that the new destination can not any
* longer be reached via this node.
* (node.lostAllLinks()=>cluster.bcastLostRoute())
*
* 5: A cluster local system node becomes unavailable.
* => Remove all references to this node from the local
* routing tables. Note: This is a completely node
* local operation.
* (node.lostAllLinks()=>network.removeAsRouter())
* => Send messages to all directly connected slave nodes
* containing information about loss of the node
* (node.establishedContact()=>cluster.multicastLostRoute())
*
*/
static void node_established_contact(struct tipc_node *n_ptr)
{
tipc_k_signal((Handler)tipc_named_node_up, n_ptr->addr);
/* Syncronize broadcast acks */
n_ptr->bclink.acked = tipc_bclink_get_last_sent();
if (n_ptr->bclink.supported) {
tipc_nmap_add(&tipc_bcast_nmap, n_ptr->addr);
if (n_ptr->addr < tipc_own_addr)
tipc_own_tag++;
}
}
static void node_name_purge_complete(unsigned long node_addr)
{
struct tipc_node *n_ptr;
read_lock_bh(&tipc_net_lock);
n_ptr = tipc_node_find(node_addr);
if (n_ptr) {
tipc_node_lock(n_ptr);
n_ptr->block_setup &= ~WAIT_NAMES_GONE;
tipc_node_unlock(n_ptr);
}
read_unlock_bh(&tipc_net_lock);
}
static void node_lost_contact(struct tipc_node *n_ptr)
{
char addr_string[16];
u32 i;
info("Lost contact with %s\n",
tipc_addr_string_fill(addr_string, n_ptr->addr));
/* Flush broadcast link info associated with lost node */
if (n_ptr->bclink.supported) {
n_ptr->bclink.gap_after = n_ptr->bclink.gap_to = 0;
while (n_ptr->bclink.deferred_head) {
struct sk_buff *buf = n_ptr->bclink.deferred_head;
n_ptr->bclink.deferred_head = buf->next;
buf_discard(buf);
}
if (n_ptr->bclink.defragm) {
buf_discard(n_ptr->bclink.defragm);
n_ptr->bclink.defragm = NULL;
}
tipc_nmap_remove(&tipc_bcast_nmap, n_ptr->addr);
tipc_bclink_acknowledge(n_ptr,
mod(n_ptr->bclink.acked + 10000));
if (n_ptr->addr < tipc_own_addr)
tipc_own_tag--;
n_ptr->bclink.supported = 0;
}
/* Abort link changeover */
for (i = 0; i < MAX_BEARERS; i++) {
struct link *l_ptr = n_ptr->links[i];
if (!l_ptr)
continue;
l_ptr->reset_checkpoint = l_ptr->next_in_no;
l_ptr->exp_msg_count = 0;
tipc_link_reset_fragments(l_ptr);
}
/* Notify subscribers */
tipc_nodesub_notify(n_ptr);
/* Prevent re-contact with node until cleanup is done */
n_ptr->block_setup = WAIT_PEER_DOWN | WAIT_NAMES_GONE;
tipc_k_signal((Handler)node_name_purge_complete, n_ptr->addr);
}
struct sk_buff *tipc_node_get_nodes(const void *req_tlv_area, int req_tlv_space)
{
u32 domain;
struct sk_buff *buf;
struct tipc_node *n_ptr;
struct tipc_node_info node_info;
u32 payload_size;
if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_NET_ADDR))
return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
domain = ntohl(*(__be32 *)TLV_DATA(req_tlv_area));
if (!tipc_addr_domain_valid(domain))
return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
" (network address)");
read_lock_bh(&tipc_net_lock);
if (!tipc_num_nodes) {
read_unlock_bh(&tipc_net_lock);
return tipc_cfg_reply_none();
}
/* For now, get space for all other nodes */
payload_size = TLV_SPACE(sizeof(node_info)) * tipc_num_nodes;
if (payload_size > 32768u) {
read_unlock_bh(&tipc_net_lock);
return tipc_cfg_reply_error_string(TIPC_CFG_NOT_SUPPORTED
" (too many nodes)");
}
buf = tipc_cfg_reply_alloc(payload_size);
if (!buf) {
read_unlock_bh(&tipc_net_lock);
return NULL;
}
/* Add TLVs for all nodes in scope */
list_for_each_entry(n_ptr, &tipc_node_list, list) {
if (!tipc_in_scope(domain, n_ptr->addr))
continue;
node_info.addr = htonl(n_ptr->addr);
node_info.up = htonl(tipc_node_is_up(n_ptr));
tipc_cfg_append_tlv(buf, TIPC_TLV_NODE_INFO,
&node_info, sizeof(node_info));
}
read_unlock_bh(&tipc_net_lock);
return buf;
}
struct sk_buff *tipc_node_get_links(const void *req_tlv_area, int req_tlv_space)
{
u32 domain;
struct sk_buff *buf;
struct tipc_node *n_ptr;
struct tipc_link_info link_info;
u32 payload_size;
if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_NET_ADDR))
return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
domain = ntohl(*(__be32 *)TLV_DATA(req_tlv_area));
if (!tipc_addr_domain_valid(domain))
return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
" (network address)");
if (tipc_mode != TIPC_NET_MODE)
return tipc_cfg_reply_none();
read_lock_bh(&tipc_net_lock);
/* Get space for all unicast links + multicast link */
payload_size = TLV_SPACE(sizeof(link_info)) *
(atomic_read(&tipc_num_links) + 1);
if (payload_size > 32768u) {
read_unlock_bh(&tipc_net_lock);
return tipc_cfg_reply_error_string(TIPC_CFG_NOT_SUPPORTED
" (too many links)");
}
buf = tipc_cfg_reply_alloc(payload_size);
if (!buf) {
read_unlock_bh(&tipc_net_lock);
return NULL;
}
/* Add TLV for broadcast link */
link_info.dest = htonl(tipc_cluster_mask(tipc_own_addr));
link_info.up = htonl(1);
strlcpy(link_info.str, tipc_bclink_name, TIPC_MAX_LINK_NAME);
tipc_cfg_append_tlv(buf, TIPC_TLV_LINK_INFO, &link_info, sizeof(link_info));
/* Add TLVs for any other links in scope */
list_for_each_entry(n_ptr, &tipc_node_list, list) {
u32 i;
if (!tipc_in_scope(domain, n_ptr->addr))
continue;
tipc_node_lock(n_ptr);
for (i = 0; i < MAX_BEARERS; i++) {
if (!n_ptr->links[i])
continue;
link_info.dest = htonl(n_ptr->addr);
link_info.up = htonl(tipc_link_is_up(n_ptr->links[i]));
strcpy(link_info.str, n_ptr->links[i]->name);
tipc_cfg_append_tlv(buf, TIPC_TLV_LINK_INFO,
&link_info, sizeof(link_info));
}
tipc_node_unlock(n_ptr);
}
read_unlock_bh(&tipc_net_lock);
return buf;
}