tipc: fix link attribute propagation bug

commit d01332f1acacc0cb43a61f4244dd2b846d4cd585 upstream.

Changing certain link attributes (link tolerance and link priority)
from the TIPC management tool is supposed to automatically take
effect at both endpoints of the affected link.

Currently the media address is not instantiated for the link and is
used uninstantiated when crafting protocol messages designated for the
peer endpoint. This means that changing a link property currently
results in the property being changed on the local machine but the
protocol message designated for the peer gets lost. Resulting in
property discrepancy between the endpoints.

In this patch we resolve this by using the media address from the
link entry and using the bearer transmit function to send it. Hence,
we can now eliminate the redundant function tipc_link_prot_xmit() and
the redundant field tipc_link::media_addr.

Fixes: 2af5ae3 (tipc: clean up unused code and structures)
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Reported-by: Jason Hu <huzhijiang@gmail.com>
Signed-off-by: Richard Alpe <richard.alpe@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[backported to 4.4 by Tommi Rantala]
Signed-off-by: Tommi Rantala <tommi.t.rantala@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Richard Alpe

net/tipc/link.c

@@ -1084,25 +1084,6 @@ int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
 	return rc;
 }
 
-/*
- * Send protocol message to the other endpoint.
- */
-void tipc_link_proto_xmit(struct tipc_link *l, u32 msg_typ, int probe_msg,
-			  u32 gap, u32 tolerance, u32 priority)
-{
-	struct sk_buff *skb = NULL;
-	struct sk_buff_head xmitq;
-
-	__skb_queue_head_init(&xmitq);
-	tipc_link_build_proto_msg(l, msg_typ, probe_msg, gap,
-				  tolerance, priority, &xmitq);
-	skb = __skb_dequeue(&xmitq);
-	if (!skb)
-		return;
-	tipc_bearer_xmit_skb(l->net, l->bearer_id, skb, l->media_addr);
-	l->rcv_unacked = 0;
-}
-
 static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
 				      u16 rcvgap, int tolerance, int priority,
 				      struct sk_buff_head *xmitq)
@@ -1636,9 +1617,12 @@ int tipc_nl_link_set(struct sk_buff *skb, struct genl_info *info)
 	char *name;
 	struct tipc_link *link;
 	struct tipc_node *node;
+	struct sk_buff_head xmitq;
 	struct nlattr *attrs[TIPC_NLA_LINK_MAX + 1];
 	struct net *net = sock_net(skb->sk);
 
+	__skb_queue_head_init(&xmitq);
+
 	if (!info->attrs[TIPC_NLA_LINK])
 		return -EINVAL;
 
@@ -1683,14 +1667,14 @@ int tipc_nl_link_set(struct sk_buff *skb, struct genl_info *info)
 
 			tol = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
 			link->tolerance = tol;
-			tipc_link_proto_xmit(link, STATE_MSG, 0, 0, tol, 0);
+			tipc_link_build_proto_msg(link, STATE_MSG, 0, 0, tol, 0, &xmitq);
 		}
 		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);
+			tipc_link_build_proto_msg(link, STATE_MSG, 0, 0, 0, prio, &xmitq);
 		}
 		if (props[TIPC_NLA_PROP_WIN]) {
 			u32 win;
@@ -1702,7 +1686,7 @@ int tipc_nl_link_set(struct sk_buff *skb, struct genl_info *info)
 
 out:
 	tipc_node_unlock(node);
-
+	tipc_bearer_xmit(net, bearer_id, &xmitq, &node->links[bearer_id].maddr);
 	return res;
 }
 

net/tipc/link.h

@@ -153,7 +153,6 @@ struct tipc_stats {
 struct tipc_link {
 	u32 addr;
 	char name[TIPC_MAX_LINK_NAME];
-	struct tipc_media_addr *media_addr;
 	struct net *net;
 
 	/* Management and link supervision data */