tipc: add new functions for multicast and broadcast distribution

We add a new broadcast link transmit function in bclink.c and a new
receive function in socket.c. The purpose is to move the branching
between external and internal destination down to the link layer,
just as we have done with unicast in earlier commits. We also make
use of the new link-independent fragmentation support that was
introduced in an earlier commit series.

This gives a shorter and simpler code path, and makes it possible
to obtain copy-free buffer delivery to all node local destination
sockets.

The new transmission code is added in parallel with the existing one,
and will be used by the socket multicast send function in the next
commit in this series.

Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Reviewed-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 35 insertions, 0 deletions

diff --git a/net/tipc/msg.c b/net/tipc/msg.c
index ce6d929d66d2..9682296f5e7c 100644
--- a/net/tipc/msg.c
+++ b/net/tipc/msg.c
@@ -417,3 +417,38 @@ int tipc_msg_eval(struct sk_buff *buf, u32 *dnode)
 	msg_set_destport(msg, dport);
 	return TIPC_OK;
 }
+
+/* tipc_msg_reassemble() - clone a buffer chain of fragments and
+ *                         reassemble the clones into one message
+ */
+struct sk_buff *tipc_msg_reassemble(struct sk_buff *chain)
+{
+	struct sk_buff *buf = chain;
+	struct sk_buff *frag = buf;
+	struct sk_buff *head = NULL;
+	int hdr_sz;
+
+	/* Copy header if single buffer */
+	if (!buf->next) {
+		hdr_sz = skb_headroom(buf) + msg_hdr_sz(buf_msg(buf));
+		return __pskb_copy(buf, hdr_sz, GFP_ATOMIC);
+	}
+
+	/* Clone all fragments and reassemble */
+	while (buf) {
+		frag = skb_clone(buf, GFP_ATOMIC);
+		if (!frag)
+			goto error;
+		frag->next = NULL;
+		if (tipc_buf_append(&head, &frag))
+			break;
+		if (!head)
+			goto error;
+		buf = buf->next;
+	}
+	return frag;
+error:
+	pr_warn("Failed do clone local mcast rcv buffer\n");
+	kfree_skb(head);
+	return NULL;
+}