Merge branch 'tipc-link-setup-improvements'

Jon Maloy says:

====================
tipc: improvements to the link setup algorithm

This series addresses some smaller issues regarding the link setup
algorithm. The first commit fixes a rare bug we have discovered during
testing; the second one may have some future impact on cluster
scalabilty, while remaining ones can be regarded as cosmetic in
a wider sense of the word.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/link.c

@@ -140,6 +140,7 @@ struct tipc_link {
 	char if_name[TIPC_MAX_IF_NAME];
 	u32 priority;
 	char net_plane;
+	u16 rst_cnt;
 
 	/* Failover/synch */
 	u16 drop_point;
@@ -699,42 +700,37 @@ static void link_profile_stats(struct tipc_link *l)
 		l->stats.msg_length_profile[6]++;
 }
 
-/* tipc_link_timeout - perform periodic task as instructed from node timeout
- */
 /* tipc_link_timeout - perform periodic task as instructed from node timeout
  */
 int tipc_link_timeout(struct tipc_link *l, struct sk_buff_head *xmitq)
 {
-	int rc = 0;
-	int mtyp = STATE_MSG;
-	bool xmit = false;
-	bool prb = false;
+	int mtyp, rc = 0;
+	bool state = false;
+	bool probe = false;
+	bool setup = false;
 	u16 bc_snt = l->bc_sndlink->snd_nxt - 1;
 	u16 bc_acked = l->bc_rcvlink->acked;
-	bool bc_up = link_is_up(l->bc_rcvlink);
 
 	link_profile_stats(l);
 
 	switch (l->state) {
 	case LINK_ESTABLISHED:
 	case LINK_SYNCHING:
-		if (!l->silent_intv_cnt) {
-			if (bc_up && (bc_acked != bc_snt))
-				xmit = true;
-		} else if (l->silent_intv_cnt <= l->abort_limit) {
-			xmit = true;
-			prb = true;
-		} else {
-			rc |= tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
-		}
-		l->silent_intv_cnt++;
+		if (l->silent_intv_cnt > l->abort_limit)
+			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
+		mtyp = STATE_MSG;
+		state = bc_acked != bc_snt;
+		probe = l->silent_intv_cnt;
+		if (probe)
+			l->silent_intv_cnt++;
 		break;
 	case LINK_RESET:
-		xmit = true;
+		setup = l->rst_cnt++ <= 4;
+		setup |= !(l->rst_cnt % 16);
 		mtyp = RESET_MSG;
 		break;
 	case LINK_ESTABLISHING:
-		xmit = true;
+		setup = true;
 		mtyp = ACTIVATE_MSG;
 		break;
 	case LINK_PEER_RESET:
@@ -745,8 +741,8 @@ int tipc_link_timeout(struct tipc_link *l, struct sk_buff_head *xmitq)
 		break;
 	}
 
-	if (xmit)
-		tipc_link_build_proto_msg(l, mtyp, prb, 0, 0, 0, xmitq);
+	if (state || probe || setup)
+		tipc_link_build_proto_msg(l, mtyp, probe, 0, 0, 0, xmitq);
 
 	return rc;
 }
@@ -833,6 +829,7 @@ void tipc_link_reset(struct tipc_link *l)
 	l->rcv_nxt = 1;
 	l->acked = 0;
 	l->silent_intv_cnt = 0;
+	l->rst_cnt = 0;
 	l->stats.recv_info = 0;
 	l->stale_count = 0;
 	l->bc_peer_is_up = false;
@@ -1110,12 +1107,12 @@ static bool tipc_link_release_pkts(struct tipc_link *l, u16 acked)
 	return released;
 }
 
-/* tipc_link_build_ack_msg: prepare link acknowledge message for transmission
+/* tipc_link_build_state_msg: prepare link state message for transmission
  *
  * Note that sending of broadcast ack is coordinated among nodes, to reduce
  * risk of ack storms towards the sender
  */
-int tipc_link_build_ack_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
+int tipc_link_build_state_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
 {
 	if (!l)
 		return 0;
@@ -1140,11 +1137,17 @@ int tipc_link_build_ack_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
 void tipc_link_build_reset_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
 {
 	int mtyp = RESET_MSG;
+	struct sk_buff *skb;
 
 	if (l->state == LINK_ESTABLISHING)
 		mtyp = ACTIVATE_MSG;
 
 	tipc_link_build_proto_msg(l, mtyp, 0, 0, 0, 0, xmitq);
+
+	/* Inform peer that this endpoint is going down if applicable */
+	skb = skb_peek_tail(xmitq);
+	if (skb && (l->state == LINK_RESET))
+		msg_set_peer_stopping(buf_msg(skb), 1);
 }
 
 /* tipc_link_build_nack_msg: prepare link nack message for transmission
@@ -1219,7 +1222,7 @@ int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
 		if (!tipc_data_input(l, skb, l->inputq))
 			rc |= tipc_link_input(l, skb, l->inputq);
 		if (unlikely(++l->rcv_unacked >= TIPC_MIN_LINK_WIN))
-			rc |= tipc_link_build_ack_msg(l, xmitq);
+			rc |= tipc_link_build_state_msg(l, xmitq);
 		if (unlikely(rc & ~TIPC_LINK_SND_BC_ACK))
 			break;
 	} while ((skb = __skb_dequeue(defq)));
@@ -1411,7 +1414,9 @@ static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
 			l->priority = peers_prio;
 
 		/* ACTIVATE_MSG serves as PEER_RESET if link is already down */
-		if ((mtyp == RESET_MSG) || !link_is_up(l))
+		if (msg_peer_stopping(hdr))
+			rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
+		else if ((mtyp == RESET_MSG) || !link_is_up(l))
 			rc = tipc_link_fsm_evt(l, LINK_PEER_RESET_EVT);
 
 		/* ACTIVATE_MSG takes up link if it was already locally reset */

net/tipc/link.h

@@ -123,7 +123,7 @@ int tipc_nl_parse_link_prop(struct nlattr *prop, struct nlattr *props[]);
 int tipc_link_timeout(struct tipc_link *l, struct sk_buff_head *xmitq);
 int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
 		  struct sk_buff_head *xmitq);
-int tipc_link_build_ack_msg(struct tipc_link *l, struct sk_buff_head *xmitq);
+int tipc_link_build_state_msg(struct tipc_link *l, struct sk_buff_head *xmitq);
 void tipc_link_add_bc_peer(struct tipc_link *snd_l,
 			   struct tipc_link *uc_l,
 			   struct sk_buff_head *xmitq);

net/tipc/msg.h

@@ -715,6 +715,16 @@ static inline void msg_set_redundant_link(struct tipc_msg *m, u32 r)
 	msg_set_bits(m, 5, 12, 0x1, r);
 }
 
+static inline u32 msg_peer_stopping(struct tipc_msg *m)
+{
+	return msg_bits(m, 5, 13, 0x1);
+}
+
+static inline void msg_set_peer_stopping(struct tipc_msg *m, u32 s)
+{
+	msg_set_bits(m, 5, 13, 0x1, s);
+}
+
 static inline char *msg_media_addr(struct tipc_msg *m)
 {
 	return (char *)&m->hdr[TIPC_MEDIA_INFO_OFFSET];

net/tipc/node.c

@@ -545,6 +545,9 @@ static void __tipc_node_link_up(struct tipc_node *n, int bearer_id,
 	pr_debug("Established link <%s> on network plane %c\n",
 		 tipc_link_name(nl), tipc_link_plane(nl));
 
+	/* Ensure that a STATE message goes first */
+	tipc_link_build_state_msg(nl, xmitq);
+
 	/* First link? => give it both slots */
 	if (!ol) {
 		*slot0 = bearer_id;
@@ -581,8 +584,12 @@ static void __tipc_node_link_up(struct tipc_node *n, int bearer_id,
 static void tipc_node_link_up(struct tipc_node *n, int bearer_id,
 			      struct sk_buff_head *xmitq)
 {
+	struct tipc_media_addr *maddr;
+
 	tipc_node_write_lock(n);
 	__tipc_node_link_up(n, bearer_id, xmitq);
+	maddr = &n->links[bearer_id].maddr;
+	tipc_bearer_xmit(n->net, bearer_id, xmitq, maddr);
 	tipc_node_write_unlock(n);
 }
 
@@ -1279,7 +1286,7 @@ static void tipc_node_bc_rcv(struct net *net, struct sk_buff *skb, int bearer_id
 	/* Broadcast ACKs are sent on a unicast link */
 	if (rc & TIPC_LINK_SND_BC_ACK) {
 		tipc_node_read_lock(n);
-		tipc_link_build_ack_msg(le->link, &xmitq);
+		tipc_link_build_state_msg(le->link, &xmitq);
 		tipc_node_read_unlock(n);
 	}