[net-next 3/3] tipc: confgiure and apply UDP bearer MTU on running links

[GhantaKrishnamurthy MohanKrishna <mohan.krishna.ghanta.krishnamurthy@ericsson.com>]

Currently, we have option to configure MTU of UDP media. The configured
MTU takes effect on the links going up after that moment. I.e, a user
has to reset bearer to have new value applied across its links. This is
confusing and disturbing on a running cluster.

We now introduce the functionality to change the default UDP bearer MTU
in struct tipc_bearer. Additionally, the links are updated dynamically,
without any need for a reset, when bearer value is changed. We leverage
the existing per-link functionality and the design being symetrical to
the confguration of link tolerance.

Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: GhantaKrishnamurthy MohanKrishna <mohan.krishna.ghanta.krishnamurthy@ericsson.com>
---
 net/tipc/bearer.c | 16 +++++++++++++++-
 net/tipc/node.c   | 12 +++++++++---
 net/tipc/node.h   |  2 +-
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index a22caf9e5a18..2dfb492a7c94 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c
@@ -697,6 +697,9 @@ static int __tipc_nl_add_bearer(struct tipc_nl_msg *msg,
 		goto prop_msg_full;
 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN, bearer->window))
 		goto prop_msg_full;
+	if (bearer->media->type_id == TIPC_MEDIA_TYPE_UDP)
+		if (nla_put_u32(msg->skb, TIPC_NLA_PROP_MTU, bearer->mtu))
+			goto prop_msg_full;
 
 	nla_nest_end(msg->skb, prop);
 
@@ -979,12 +982,23 @@ int __tipc_nl_bearer_set(struct sk_buff *skb, struct genl_info *info)
 
 		if (props[TIPC_NLA_PROP_TOL]) {
 			b->tolerance = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
-			tipc_node_apply_tolerance(net, b);
+			tipc_node_apply_property(net, b, TIPC_NLA_PROP_TOL);
 		}
 		if (props[TIPC_NLA_PROP_PRIO])
 			b->priority = nla_get_u32(props[TIPC_NLA_PROP_PRIO]);
 		if (props[TIPC_NLA_PROP_WIN])
 			b->window = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
+		if (props[TIPC_NLA_PROP_MTU]) {
+			if (b->media->type_id != TIPC_MEDIA_TYPE_UDP)
+				return -EINVAL;
+#ifdef CONFIG_TIPC_MEDIA_UDP
+			if (tipc_udp_mtu_bad(nla_get_u32
+					     (props[TIPC_NLA_PROP_MTU])))
+				return -EINVAL;
+			b->mtu = nla_get_u32(props[TIPC_NLA_PROP_MTU]);
+			tipc_node_apply_property(net, b, TIPC_NLA_PROP_MTU);
+#endif
+		}
 	}
 
 	return 0;
diff --git a/net/tipc/node.c b/net/tipc/node.c
index c77dd2f3c589..b71e4e376bb9 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -1681,7 +1681,8 @@ void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b)
 	kfree_skb(skb);
 }
 
-void tipc_node_apply_tolerance(struct net *net, struct tipc_bearer *b)
+void tipc_node_apply_property(struct net *net, struct tipc_bearer *b,
+			      int prop)
 {
 	struct tipc_net *tn = tipc_net(net);
 	int bearer_id = b->identity;
@@ -1696,8 +1697,13 @@ void tipc_node_apply_tolerance(struct net *net, struct tipc_bearer *b)
 	list_for_each_entry_rcu(n, &tn->node_list, list) {
 		tipc_node_write_lock(n);
 		e = &n->links[bearer_id];
-		if (e->link)
-			tipc_link_set_tolerance(e->link, b->tolerance, &xmitq);
+		if (e->link) {
+			if (prop == TIPC_NLA_PROP_TOL)
+				tipc_link_set_tolerance(e->link, b->tolerance,
+							&xmitq);
+			else if (prop == TIPC_NLA_PROP_MTU)
+				tipc_link_set_mtu(e->link, b->mtu);
+		}
 		tipc_node_write_unlock(n);
 		tipc_bearer_xmit(net, bearer_id, &xmitq, &e->maddr);
 	}
diff --git a/net/tipc/node.h b/net/tipc/node.h
index f24b83500df1..bb271a37c93f 100644
--- a/net/tipc/node.h
+++ b/net/tipc/node.h
@@ -67,7 +67,7 @@ void tipc_node_check_dest(struct net *net, u32 onode, u8 *peer_id128,
 			  struct tipc_media_addr *maddr,
 			  bool *respond, bool *dupl_addr);
 void tipc_node_delete_links(struct net *net, int bearer_id);
-void tipc_node_apply_tolerance(struct net *net, struct tipc_bearer *b);
+void tipc_node_apply_property(struct net *net, struct tipc_bearer *b, int prop);
 int tipc_node_get_linkname(struct net *net, u32 bearer_id, u32 node,
 			   char *linkname, size_t len);
 int tipc_node_xmit(struct net *net, struct sk_buff_head *list, u32 dnode,
-- 
2.1.4