tipc: add function for checking broadcast support in bearer

As a preparation for the 'replicast' functionality we are going to
introduce in the next commits, we need the broadcast base structure to
store whether bearer broadcast is available at all from the currently
used bearer or bearers.

We do this by adding a new function tipc_bearer_bcast_support() to
the bearer layer, and letting the bearer selection function in
bcast.c use this to give a new boolean field, 'bcast_support' the
appropriate value.

Reviewed-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com>
Acked-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 c35fad3..3256276 100644
--- a/net/tipc/bcast.c
+++ b/net/tipc/bcast.c
@@ -1,7 +1,7 @@
 /*
  * net/tipc/bcast.c: TIPC broadcast code
  *
- * Copyright (c) 2004-2006, 2014-2015, Ericsson AB
+ * Copyright (c) 2004-2006, 2014-2016, Ericsson AB
  * Copyright (c) 2004, Intel Corporation.
  * Copyright (c) 2005, 2010-2011, Wind River Systems
  * All rights reserved.
@@ -54,12 +54,14 @@
  * @inputq: data input queue; will only carry SOCK_WAKEUP messages
  * @dest: array keeping number of reachable destinations per bearer
  * @primary_bearer: a bearer having links to all broadcast destinations, if any
+ * @bcast_support: indicates if primary bearer, if any, supports broadcast
  */
 struct tipc_bc_base {
 	struct tipc_link *link;
 	struct sk_buff_head inputq;
 	int dests[MAX_BEARERS];
 	int primary_bearer;
+	bool bcast_support;
 };
 
 static struct tipc_bc_base *tipc_bc_base(struct net *net)
@@ -79,9 +81,10 @@
 {
 	struct tipc_bc_base *bb = tipc_bc_base(net);
 	int all_dests =  tipc_link_bc_peers(bb->link);
-	int i, mtu;
+	int i, mtu, prim;
 
 	bb->primary_bearer = INVALID_BEARER_ID;
+	bb->bcast_support = true;
 
 	if (!all_dests)
 		return;
@@ -93,7 +96,7 @@
 		mtu = tipc_bearer_mtu(net, i);
 		if (mtu < tipc_link_mtu(bb->link))
 			tipc_link_set_mtu(bb->link, mtu);
-
+		bb->bcast_support &= tipc_bearer_bcast_support(net, i);
 		if (bb->dests[i] < all_dests)
 			continue;
 
@@ -103,6 +106,9 @@
 		if ((i ^ tipc_own_addr(net)) & 1)
 			break;
 	}
+	prim = bb->primary_bearer;
+	if (prim != INVALID_BEARER_ID)
+		bb->bcast_support = tipc_bearer_bcast_support(net, prim);
 }
 
 void tipc_bcast_inc_bearer_dst_cnt(struct net *net, int bearer_id)
diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index 52d7476..33a5bdf 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c
@@ -431,7 +431,7 @@
 	memset(&b->bcast_addr, 0, sizeof(b->bcast_addr));
 	memcpy(b->bcast_addr.value, dev->broadcast, b->media->hwaddr_len);
 	b->bcast_addr.media_id = b->media->type_id;
-	b->bcast_addr.broadcast = 1;
+	b->bcast_addr.broadcast = TIPC_BROADCAST_SUPPORT;
 	b->mtu = dev->mtu;
 	b->media->raw2addr(b, &b->addr, (char *)dev->dev_addr);
 	rcu_assign_pointer(dev->tipc_ptr, b);
@@ -482,6 +482,19 @@
 	return 0;
 }
 
+bool tipc_bearer_bcast_support(struct net *net, u32 bearer_id)
+{
+	bool supp = false;
+	struct tipc_bearer *b;
+
+	rcu_read_lock();
+	b = bearer_get(net, bearer_id);
+	if (b)
+		supp = (b->bcast_addr.broadcast == TIPC_BROADCAST_SUPPORT);
+	rcu_read_unlock();
+	return supp;
+}
+
 int tipc_bearer_mtu(struct net *net, u32 bearer_id)
 {
 	int mtu = 0;
diff --git a/net/tipc/bearer.h b/net/tipc/bearer.h
index 278ff7f..635c908 100644
--- a/net/tipc/bearer.h
+++ b/net/tipc/bearer.h
@@ -60,9 +60,14 @@
 #define TIPC_MEDIA_TYPE_IB	2
 #define TIPC_MEDIA_TYPE_UDP	3
 
-/* minimum bearer MTU */
+/* Minimum bearer MTU */
 #define TIPC_MIN_BEARER_MTU	(MAX_H_SIZE + INT_H_SIZE)
 
+/* Identifiers for distinguishing between broadcast/multicast and replicast
+ */
+#define TIPC_BROADCAST_SUPPORT  1
+#define TIPC_REPLICAST_SUPPORT  2
+
 /**
  * struct tipc_media_addr - destination address used by TIPC bearers
  * @value: address info (format defined by media)
@@ -210,6 +215,7 @@
 void tipc_bearer_cleanup(void);
 void tipc_bearer_stop(struct net *net);
 int tipc_bearer_mtu(struct net *net, u32 bearer_id);
+bool tipc_bearer_bcast_support(struct net *net, u32 bearer_id);
 void tipc_bearer_xmit_skb(struct net *net, u32 bearer_id,
 			  struct sk_buff *skb,
 			  struct tipc_media_addr *dest);
diff --git a/net/tipc/udp_media.c b/net/tipc/udp_media.c
index b58dc95..46061cf 100644
--- a/net/tipc/udp_media.c
+++ b/net/tipc/udp_media.c
@@ -113,7 +113,7 @@
 	memcpy(addr->value, ua, sizeof(struct udp_media_addr));
 
 	if (tipc_udp_is_mcast_addr(ua))
-		addr->broadcast = 1;
+		addr->broadcast = TIPC_BROADCAST_SUPPORT;
 }
 
 /* tipc_udp_addr2str - convert ip/udp address to string */
@@ -229,7 +229,7 @@
 		goto out;
 	}
 
-	if (!addr->broadcast || list_empty(&ub->rcast.list))
+	if (addr->broadcast != TIPC_REPLICAST_SUPPORT)
 		return tipc_udp_xmit(net, skb, ub, src, dst);
 
 	/* Replicast, send an skb to each configured IP address */
@@ -296,7 +296,7 @@
 	else if (ntohs(addr->proto) == ETH_P_IPV6)
 		pr_info("New replicast peer: %pI6\n", &rcast->addr.ipv6);
 #endif
-
+	b->bcast_addr.broadcast = TIPC_REPLICAST_SUPPORT;
 	list_add_rcu(&rcast->list, &ub->rcast.list);
 	return 0;
 }
@@ -681,7 +681,7 @@
 		goto err;
 
 	b->bcast_addr.media_id = TIPC_MEDIA_TYPE_UDP;
-	b->bcast_addr.broadcast = 1;
+	b->bcast_addr.broadcast = TIPC_BROADCAST_SUPPORT;
 	rcu_assign_pointer(b->media_ptr, ub);
 	rcu_assign_pointer(ub->bearer, b);
 	tipc_udp_media_addr_set(&b->addr, &local);