[TIPC]: Force linearization of non-linear sk_buffs

This patch allows TIPC to process incoming messages that are
stored in a fragmented sk_buff, by forcing the linearization
of any such messages it receives.

Note: This is an interim solution to allow TIPC to operate with
Ethernet devices that generate non-linear buffers (such as the
gianfar driver), until such time as the rest of TIPC is enhanced
to handle sk_buffs with multiple data areas.
Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/core.h

@@ -337,4 +337,16 @@ static inline void buf_discard(struct sk_buff *skb)
 	kfree_skb(skb);
 }
 
+/**
+ * buf_linearize - convert a TIPC message buffer into a single contiguous piece
+ * @skb: message buffer
+ *
+ * Returns 0 on success.
+ */
+
+static inline int buf_linearize(struct sk_buff *skb)
+{
+	return skb_linearize(skb);
+}
+
 #endif

net/tipc/link.c

@@ -1811,6 +1811,12 @@ void tipc_recv_msg(struct sk_buff *head, struct tipc_bearer *tb_ptr)
 #endif
 			msg_dbg(msg,"<REC<");
 
+		/* Ensure message data is a single contiguous unit */
+
+		if (unlikely(buf_linearize(buf))) {
+			goto cont;
+		}
+
 		if (unlikely(msg_non_seq(msg))) {
 			link_recv_non_seq(buf);
 			continue;