tipc: simplify link mtu negotiation
When a link is being established, the two endpoints advertise their
respective interface MTU in the transmitted RESET and ACTIVATE messages.
If there is any difference, the lower of the two MTUs will be selected
for use by both endpoints.
However, as a remnant of earlier attempts to introduce TIPC level
routing. there also exists an MTU discovery mechanism. If an intermediate
node has a lower MTU than the two endpoints, they will discover this
through a bisectional approach, and finally adopt this MTU for common use.
Since there is no TIPC level routing, and probably never will be,
this mechanism doesn't make any sense, and only serves to make the
link level protocol unecessarily complex.
In this commit, we eliminate the MTU discovery algorithm,and fall back
to the simple MTU advertising approach. This change is fully backwards
compatible.
Reviewed-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c
index ae558dd..c5cbdcb 100644
--- a/net/tipc/bcast.c
+++ b/net/tipc/bcast.c
@@ -413,7 +413,7 @@
*/
if (((seqno - tn->own_addr) % TIPC_MIN_LINK_WIN) == 0) {
tipc_link_proto_xmit(node->active_links[node->addr & 1],
- STATE_MSG, 0, 0, 0, 0, 0);
+ STATE_MSG, 0, 0, 0, 0);
tn->bcl->stats.sent_acks++;
}
}
@@ -899,7 +899,7 @@
skb_queue_head_init(&bclink->inputq);
bcl->owner = &bclink->node;
bcl->owner->net = net;
- bcl->max_pkt = MAX_PKT_DEFAULT_MCAST;
+ bcl->mtu = MAX_PKT_DEFAULT_MCAST;
tipc_link_set_queue_limits(bcl, BCLINK_WIN_DEFAULT);
bcl->bearer_id = MAX_BEARERS;
rcu_assign_pointer(tn->bearer_list[MAX_BEARERS], &bcbearer->bearer);
diff --git a/net/tipc/link.c b/net/tipc/link.c
index b1e1795..a6b30df 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -136,34 +136,6 @@
return l->owner->active_links[1];
}
-static void link_init_max_pkt(struct tipc_link *l_ptr)
-{
- struct tipc_node *node = l_ptr->owner;
- struct tipc_net *tn = net_generic(node->net, tipc_net_id);
- struct tipc_bearer *b_ptr;
- u32 max_pkt;
-
- rcu_read_lock();
- b_ptr = rcu_dereference_rtnl(tn->bearer_list[l_ptr->bearer_id]);
- if (!b_ptr) {
- rcu_read_unlock();
- return;
- }
- max_pkt = (b_ptr->mtu & ~3);
- rcu_read_unlock();
-
- if (max_pkt > MAX_MSG_SIZE)
- max_pkt = MAX_MSG_SIZE;
-
- l_ptr->max_pkt_target = max_pkt;
- if (l_ptr->max_pkt_target < MAX_PKT_DEFAULT)
- l_ptr->max_pkt = l_ptr->max_pkt_target;
- else
- l_ptr->max_pkt = MAX_PKT_DEFAULT;
-
- l_ptr->max_pkt_probes = 0;
-}
-
/*
* Simple non-static link routines (i.e. referenced outside this file)
*/
@@ -304,7 +276,8 @@
msg_set_bearer_id(msg, b_ptr->identity);
strcpy((char *)msg_data(msg), if_name);
l_ptr->net_plane = b_ptr->net_plane;
- link_init_max_pkt(l_ptr);
+ l_ptr->advertised_mtu = b_ptr->mtu;
+ l_ptr->mtu = l_ptr->advertised_mtu;
l_ptr->priority = b_ptr->priority;
tipc_link_set_queue_limits(l_ptr, b_ptr->window);
l_ptr->next_out_no = 1;
@@ -465,8 +438,8 @@
/* Link is down, accept any session */
l_ptr->peer_session = INVALID_SESSION;
- /* Prepare for max packet size negotiation */
- link_init_max_pkt(l_ptr);
+ /* Prepare for renewed mtu size negotiation */
+ l_ptr->mtu = l_ptr->advertised_mtu;
l_ptr->state = RESET_UNKNOWN;
@@ -563,11 +536,7 @@
l_ptr->checkpoint = l_ptr->next_in_no;
if (tipc_bclink_acks_missing(l_ptr->owner)) {
tipc_link_proto_xmit(l_ptr, STATE_MSG,
- 0, 0, 0, 0, 0);
- l_ptr->fsm_msg_cnt++;
- } else if (l_ptr->max_pkt < l_ptr->max_pkt_target) {
- tipc_link_proto_xmit(l_ptr, STATE_MSG,
- 1, 0, 0, 0, 0);
+ 0, 0, 0, 0);
l_ptr->fsm_msg_cnt++;
}
link_set_timer(l_ptr, cont_intv);
@@ -575,7 +544,7 @@
}
l_ptr->state = WORKING_UNKNOWN;
l_ptr->fsm_msg_cnt = 0;
- tipc_link_proto_xmit(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
+ tipc_link_proto_xmit(l_ptr, STATE_MSG, 1, 0, 0, 0);
l_ptr->fsm_msg_cnt++;
link_set_timer(l_ptr, cont_intv / 4);
break;
@@ -586,7 +555,7 @@
l_ptr->state = RESET_RESET;
l_ptr->fsm_msg_cnt = 0;
tipc_link_proto_xmit(l_ptr, ACTIVATE_MSG,
- 0, 0, 0, 0, 0);
+ 0, 0, 0, 0);
l_ptr->fsm_msg_cnt++;
link_set_timer(l_ptr, cont_intv);
break;
@@ -609,7 +578,7 @@
l_ptr->state = RESET_RESET;
l_ptr->fsm_msg_cnt = 0;
tipc_link_proto_xmit(l_ptr, ACTIVATE_MSG,
- 0, 0, 0, 0, 0);
+ 0, 0, 0, 0);
l_ptr->fsm_msg_cnt++;
link_set_timer(l_ptr, cont_intv);
break;
@@ -620,13 +589,13 @@
l_ptr->checkpoint = l_ptr->next_in_no;
if (tipc_bclink_acks_missing(l_ptr->owner)) {
tipc_link_proto_xmit(l_ptr, STATE_MSG,
- 0, 0, 0, 0, 0);
+ 0, 0, 0, 0);
l_ptr->fsm_msg_cnt++;
}
link_set_timer(l_ptr, cont_intv);
} else if (l_ptr->fsm_msg_cnt < l_ptr->abort_limit) {
tipc_link_proto_xmit(l_ptr, STATE_MSG,
- 1, 0, 0, 0, 0);
+ 1, 0, 0, 0);
l_ptr->fsm_msg_cnt++;
link_set_timer(l_ptr, cont_intv / 4);
} else { /* Link has failed */
@@ -636,7 +605,7 @@
l_ptr->state = RESET_UNKNOWN;
l_ptr->fsm_msg_cnt = 0;
tipc_link_proto_xmit(l_ptr, RESET_MSG,
- 0, 0, 0, 0, 0);
+ 0, 0, 0, 0);
l_ptr->fsm_msg_cnt++;
link_set_timer(l_ptr, cont_intv);
}
@@ -656,7 +625,7 @@
l_ptr->state = WORKING_WORKING;
l_ptr->fsm_msg_cnt = 0;
link_activate(l_ptr);
- tipc_link_proto_xmit(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
+ tipc_link_proto_xmit(l_ptr, STATE_MSG, 1, 0, 0, 0);
l_ptr->fsm_msg_cnt++;
if (l_ptr->owner->working_links == 1)
tipc_link_sync_xmit(l_ptr);
@@ -666,7 +635,7 @@
l_ptr->state = RESET_RESET;
l_ptr->fsm_msg_cnt = 0;
tipc_link_proto_xmit(l_ptr, ACTIVATE_MSG,
- 1, 0, 0, 0, 0);
+ 1, 0, 0, 0);
l_ptr->fsm_msg_cnt++;
link_set_timer(l_ptr, cont_intv);
break;
@@ -676,7 +645,7 @@
link_set_timer(l_ptr, cont_intv);
break;
case TIMEOUT_EVT:
- tipc_link_proto_xmit(l_ptr, RESET_MSG, 0, 0, 0, 0, 0);
+ tipc_link_proto_xmit(l_ptr, RESET_MSG, 0, 0, 0, 0);
l_ptr->fsm_msg_cnt++;
link_set_timer(l_ptr, cont_intv);
break;
@@ -694,7 +663,7 @@
l_ptr->state = WORKING_WORKING;
l_ptr->fsm_msg_cnt = 0;
link_activate(l_ptr);
- tipc_link_proto_xmit(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
+ tipc_link_proto_xmit(l_ptr, STATE_MSG, 1, 0, 0, 0);
l_ptr->fsm_msg_cnt++;
if (l_ptr->owner->working_links == 1)
tipc_link_sync_xmit(l_ptr);
@@ -704,7 +673,7 @@
break;
case TIMEOUT_EVT:
tipc_link_proto_xmit(l_ptr, ACTIVATE_MSG,
- 0, 0, 0, 0, 0);
+ 0, 0, 0, 0);
l_ptr->fsm_msg_cnt++;
link_set_timer(l_ptr, cont_intv);
break;
@@ -733,7 +702,7 @@
struct tipc_msg *msg = buf_msg(skb_peek(list));
unsigned int maxwin = link->window;
unsigned int imp = msg_importance(msg);
- uint mtu = link->max_pkt;
+ uint mtu = link->mtu;
uint ack = mod(link->next_in_no - 1);
uint seqno = link->next_out_no;
uint bc_last_in = link->owner->bclink.last_in;
@@ -1187,7 +1156,7 @@
link_retrieve_defq(l_ptr, &head);
if (unlikely(++l_ptr->rcv_unacked >= TIPC_MIN_LINK_WIN)) {
l_ptr->stats.sent_acks++;
- tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, 0, 0, 0, 0);
+ tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, 0, 0, 0);
}
tipc_link_input(l_ptr, skb);
skb = NULL;
@@ -1362,7 +1331,7 @@
if (tipc_link_defer_pkt(&l_ptr->deferdq, buf)) {
l_ptr->stats.deferred_recv++;
if ((skb_queue_len(&l_ptr->deferdq) % TIPC_MIN_LINK_WIN) == 1)
- tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, 0, 0, 0, 0);
+ tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, 0, 0, 0);
} else {
l_ptr->stats.duplicates++;
}
@@ -1372,7 +1341,7 @@
* Send protocol message to the other endpoint.
*/
void tipc_link_proto_xmit(struct tipc_link *l_ptr, u32 msg_typ, int probe_msg,
- u32 gap, u32 tolerance, u32 priority, u32 ack_mtu)
+ u32 gap, u32 tolerance, u32 priority)
{
struct sk_buff *buf = NULL;
struct tipc_msg *msg = l_ptr->pmsg;
@@ -1410,26 +1379,11 @@
l_ptr->stats.sent_nacks++;
msg_set_link_tolerance(msg, tolerance);
msg_set_linkprio(msg, priority);
- msg_set_max_pkt(msg, ack_mtu);
+ msg_set_max_pkt(msg, l_ptr->mtu);
msg_set_ack(msg, mod(l_ptr->next_in_no - 1));
msg_set_probe(msg, probe_msg != 0);
- if (probe_msg) {
- u32 mtu = l_ptr->max_pkt;
-
- if ((mtu < l_ptr->max_pkt_target) &&
- link_working_working(l_ptr) &&
- l_ptr->fsm_msg_cnt) {
- msg_size = (mtu + (l_ptr->max_pkt_target - mtu)/2 + 2) & ~3;
- if (l_ptr->max_pkt_probes == 10) {
- l_ptr->max_pkt_target = (msg_size - 4);
- l_ptr->max_pkt_probes = 0;
- msg_size = (mtu + (l_ptr->max_pkt_target - mtu)/2 + 2) & ~3;
- }
- l_ptr->max_pkt_probes++;
- }
-
+ if (probe_msg)
l_ptr->stats.sent_probes++;
- }
l_ptr->stats.sent_states++;
} else { /* RESET_MSG or ACTIVATE_MSG */
msg_set_ack(msg, mod(l_ptr->failover_checkpt - 1));
@@ -1438,7 +1392,7 @@
msg_set_probe(msg, 0);
msg_set_link_tolerance(msg, l_ptr->tolerance);
msg_set_linkprio(msg, l_ptr->priority);
- msg_set_max_pkt(msg, l_ptr->max_pkt_target);
+ msg_set_max_pkt(msg, l_ptr->advertised_mtu);
}
r_flag = (l_ptr->owner->working_links > tipc_link_is_up(l_ptr));
@@ -1469,8 +1423,6 @@
struct sk_buff *buf)
{
u32 rec_gap = 0;
- u32 max_pkt_info;
- u32 max_pkt_ack;
u32 msg_tol;
struct tipc_msg *msg = buf_msg(buf);
@@ -1513,15 +1465,8 @@
if (msg_linkprio(msg) > l_ptr->priority)
l_ptr->priority = msg_linkprio(msg);
- max_pkt_info = msg_max_pkt(msg);
- if (max_pkt_info) {
- if (max_pkt_info < l_ptr->max_pkt_target)
- l_ptr->max_pkt_target = max_pkt_info;
- if (l_ptr->max_pkt > l_ptr->max_pkt_target)
- l_ptr->max_pkt = l_ptr->max_pkt_target;
- } else {
- l_ptr->max_pkt = l_ptr->max_pkt_target;
- }
+ if (l_ptr->mtu > msg_max_pkt(msg))
+ l_ptr->mtu = msg_max_pkt(msg);
/* Synchronize broadcast link info, if not done previously */
if (!tipc_node_is_up(l_ptr->owner)) {
@@ -1566,18 +1511,8 @@
mod(l_ptr->next_in_no));
}
- max_pkt_ack = msg_max_pkt(msg);
- if (max_pkt_ack > l_ptr->max_pkt) {
- l_ptr->max_pkt = max_pkt_ack;
- l_ptr->max_pkt_probes = 0;
- }
-
- max_pkt_ack = 0;
- if (msg_probe(msg)) {
+ if (msg_probe(msg))
l_ptr->stats.recv_probes++;
- if (msg_size(msg) > sizeof(l_ptr->proto_msg))
- max_pkt_ack = msg_size(msg);
- }
/* Protocol message before retransmits, reduce loss risk */
if (l_ptr->owner->bclink.recv_permitted)
@@ -1585,8 +1520,8 @@
msg_last_bcast(msg));
if (rec_gap || (msg_probe(msg))) {
- tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, rec_gap, 0,
- 0, max_pkt_ack);
+ tipc_link_proto_xmit(l_ptr, STATE_MSG, 0,
+ rec_gap, 0, 0);
}
if (msg_seq_gap(msg)) {
l_ptr->stats.recv_nacks++;
@@ -1816,7 +1751,7 @@
void tipc_link_set_queue_limits(struct tipc_link *l, u32 win)
{
- int max_bulk = TIPC_MAX_PUBLICATIONS / (l->max_pkt / ITEM_SIZE);
+ int max_bulk = TIPC_MAX_PUBLICATIONS / (l->mtu / ITEM_SIZE);
l->window = win;
l->backlog[TIPC_LOW_IMPORTANCE].limit = win / 2;
@@ -1988,14 +1923,14 @@
tol = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
link_set_supervision_props(link, tol);
- tipc_link_proto_xmit(link, STATE_MSG, 0, 0, tol, 0, 0);
+ tipc_link_proto_xmit(link, STATE_MSG, 0, 0, tol, 0);
}
if (props[TIPC_NLA_PROP_PRIO]) {
u32 prio;
prio = nla_get_u32(props[TIPC_NLA_PROP_PRIO]);
link->priority = prio;
- tipc_link_proto_xmit(link, STATE_MSG, 0, 0, 0, prio, 0);
+ tipc_link_proto_xmit(link, STATE_MSG, 0, 0, 0, prio);
}
if (props[TIPC_NLA_PROP_WIN]) {
u32 win;
@@ -2100,7 +2035,7 @@
if (nla_put_u32(msg->skb, TIPC_NLA_LINK_DEST,
tipc_cluster_mask(tn->own_addr)))
goto attr_msg_full;
- if (nla_put_u32(msg->skb, TIPC_NLA_LINK_MTU, link->max_pkt))
+ if (nla_put_u32(msg->skb, TIPC_NLA_LINK_MTU, link->mtu))
goto attr_msg_full;
if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, link->next_in_no))
goto attr_msg_full;
diff --git a/net/tipc/link.h b/net/tipc/link.h
index 6e28f03..b5b4e35 100644
--- a/net/tipc/link.h
+++ b/net/tipc/link.h
@@ -123,9 +123,8 @@
* @backlog_limit: backlog queue congestion thresholds (indexed by importance)
* @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)
+ * @mtu: current maximum packet size for this link
+ * @advertised_mtu: advertised own mtu when link is being established
* @transmitq: queue for sent, non-acked messages
* @backlogq: queue for messages waiting to be sent
* @next_out_no: next sequence number to use for outbound messages
@@ -176,9 +175,8 @@
struct sk_buff *failover_skb;
/* Max packet negotiation */
- u32 max_pkt;
- u32 max_pkt_target;
- u32 max_pkt_probes;
+ u16 mtu;
+ u16 advertised_mtu;
/* Sending */
struct sk_buff_head transmq;
@@ -233,7 +231,7 @@
int __tipc_link_xmit(struct net *net, struct tipc_link *link,
struct sk_buff_head *list);
void tipc_link_proto_xmit(struct tipc_link *l_ptr, u32 msg_typ, int prob,
- u32 gap, u32 tolerance, u32 priority, u32 acked_mtu);
+ u32 gap, u32 tolerance, u32 priority);
void tipc_link_push_packets(struct tipc_link *l_ptr);
u32 tipc_link_defer_pkt(struct sk_buff_head *list, struct sk_buff *buf);
void tipc_link_set_queue_limits(struct tipc_link *l_ptr, u32 window);
diff --git a/net/tipc/node.c b/net/tipc/node.c
index f3d522c..22c059a 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -254,8 +254,8 @@
active[0] = active[1] = l_ptr;
exit:
/* Leave room for changeover header when returning 'mtu' to users: */
- n_ptr->act_mtus[0] = active[0]->max_pkt - INT_H_SIZE;
- n_ptr->act_mtus[1] = active[1]->max_pkt - INT_H_SIZE;
+ n_ptr->act_mtus[0] = active[0]->mtu - INT_H_SIZE;
+ n_ptr->act_mtus[1] = active[1]->mtu - INT_H_SIZE;
}
/**
@@ -319,11 +319,10 @@
/* Leave room for changeover header when returning 'mtu' to users: */
if (active[0]) {
- n_ptr->act_mtus[0] = active[0]->max_pkt - INT_H_SIZE;
- n_ptr->act_mtus[1] = active[1]->max_pkt - INT_H_SIZE;
+ n_ptr->act_mtus[0] = active[0]->mtu - INT_H_SIZE;
+ n_ptr->act_mtus[1] = active[1]->mtu - INT_H_SIZE;
return;
}
-
/* Loopback link went down? No fragmentation needed from now on. */
if (n_ptr->addr == tn->own_addr) {
n_ptr->act_mtus[0] = MAX_MSG_SIZE;