tipc: update node FSM when peer RESET message is received

The change made in the previous commit revealed a small flaw in the way
the node FSM is updated. When the function tipc_node_link_down() is
called for the last link to a node, we should check whether this was
caused by a local reset or by a received RESET message from the peer.
In the latter case, we can directly issue a PEER_LOST_CONTACT_EVT to
the node FSM, so that it is ready to re-establish contact. If this is
not done, the peer node will sometimes have to go through a second
establish cycle before the link becomes stable.

We fix this in this commit by conditionally issuing the mentioned
event in the function tipc_node_link_down(). We also move LINK_RESET
FSM even away from the link_reset() function and into the caller
function, partially because it is easier to follow the code when state
changes are gathered at a limited number of locations, partially
because there will be cases in future commits where we don't want the
link to go RESET mode when link_reset() is called.

Signed-off-by: Jon Maloy <[email protected]>
Acked-by: Ying Xue <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: Jon Paul Maloy

net/tipc/link.c

@@ -120,6 +120,11 @@ bool tipc_link_is_up(struct tipc_link *l)
 	return link_is_up(l);
 }
 
+bool tipc_link_peer_is_down(struct tipc_link *l)
+{
+	return l->state == LINK_PEER_RESET;
+}
+
 bool tipc_link_is_reset(struct tipc_link *l)
 {
 	return l->state & (LINK_RESET | LINK_FAILINGOVER | LINK_ESTABLISHING);
@@ -584,8 +589,6 @@ void tipc_link_purge_queues(struct tipc_link *l_ptr)
 
 void tipc_link_reset(struct tipc_link *l)
 {
-	tipc_link_fsm_evt(l, LINK_RESET_EVT);
-
 	/* Link is down, accept any session */
 	l->peer_session = WILDCARD_SESSION;
 

net/tipc/link.h

@@ -217,6 +217,7 @@ void tipc_link_build_reset_msg(struct tipc_link *l, struct sk_buff_head *xmitq);
 int tipc_link_fsm_evt(struct tipc_link *l, int evt);
 void tipc_link_reset_fragments(struct tipc_link *l_ptr);
 bool tipc_link_is_up(struct tipc_link *l);
+bool tipc_link_peer_is_down(struct tipc_link *l);
 bool tipc_link_is_reset(struct tipc_link *l);
 bool tipc_link_is_establishing(struct tipc_link *l);
 bool tipc_link_is_synching(struct tipc_link *l);

net/tipc/node.c

@@ -41,7 +41,7 @@
 #include "socket.h"
 #include "bcast.h"
 #include "discover.h"
-#define pr_debug printk
+
 /* Node FSM states and events:
  */
 enum {
@@ -420,6 +420,10 @@ static void __tipc_node_link_down(struct tipc_node *n, int *bearer_id,
 	}
 
 	if (!tipc_node_is_up(n)) {
+		if (tipc_link_peer_is_down(l))
+			tipc_node_fsm_evt(n, PEER_LOST_CONTACT_EVT);
+		tipc_node_fsm_evt(n, SELF_LOST_CONTACT_EVT);
+		tipc_link_fsm_evt(l, LINK_RESET_EVT);
 		tipc_link_reset(l);
 		tipc_link_build_reset_msg(l, xmitq);
 		*maddr = &n->links[*bearer_id].maddr;
@@ -434,6 +438,7 @@ static void __tipc_node_link_down(struct tipc_node *n, int *bearer_id,
 	n->sync_point = tnl->rcv_nxt + (U16_MAX / 2 - 1);
 	tipc_link_tnl_prepare(l, tnl, FAILOVER_MSG, xmitq);
 	tipc_link_reset(l);
+	tipc_link_fsm_evt(l, LINK_RESET_EVT);
 	tipc_link_fsm_evt(l, LINK_FAILOVER_BEGIN_EVT);
 	tipc_node_fsm_evt(n, NODE_FAILOVER_BEGIN_EVT);
 	*maddr = &n->links[tnl->bearer_id].maddr;
@@ -581,6 +586,7 @@ void tipc_node_check_dest(struct net *net, u32 onode,
 			goto exit;
 		}
 		tipc_link_reset(l);
+		tipc_link_fsm_evt(l, LINK_RESET_EVT);
 		if (n->state == NODE_FAILINGOVER)
 			tipc_link_fsm_evt(l, LINK_FAILOVER_BEGIN_EVT);
 		le->link = l;
@@ -863,9 +869,6 @@ static void node_lost_contact(struct tipc_node *n_ptr,
 			tipc_link_fsm_evt(l, LINK_FAILOVER_END_EVT);
 	}
 
-	/* Prevent re-contact with node until cleanup is done */
-	tipc_node_fsm_evt(n_ptr, SELF_LOST_CONTACT_EVT);
-
 	/* Notify publications from this node */
 	n_ptr->action_flags |= TIPC_NOTIFY_NODE_DOWN;