tipc: make media xmit call outside node spinlock context

Currently, message sending is performed through a deep call chain,
where the node spinlock is grabbed and held during a significant
part of the transmission time. This is clearly detrimental to
overall throughput performance; it would be better if we could send
the message after the spinlock has been released.

In this commit, we do instead let the call revert on the stack after
the buffer chain has been added to the transmission queue, whereafter
clones of the buffers are transmitted to the device layer outside the
spinlock scope.

As a further step in our effort to separate the roles of the node
and link entities we also move the function tipc_link_xmit() to
node.c, and rename it to tipc_node_xmit().

Reviewed-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>

1 files changed, 26 insertions, 0 deletions

diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index 00bc0e620532..eae58a6b121c 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c
@@ -470,6 +470,32 @@ void tipc_bearer_send(struct net *net, u32 bearer_id, struct sk_buff *buf,
 	rcu_read_unlock();
 }
 
+/* tipc_bearer_xmit() -send buffer to destination over bearer
+ */
+void tipc_bearer_xmit(struct net *net, u32 bearer_id,
+		      struct sk_buff_head *xmitq,
+		      struct tipc_media_addr *dst)
+{
+	struct tipc_net *tn = net_generic(net, tipc_net_id);
+	struct tipc_bearer *b;
+	struct sk_buff *skb, *tmp;
+
+	if (skb_queue_empty(xmitq))
+		return;
+
+	rcu_read_lock();
+	b = rcu_dereference_rtnl(tn->bearer_list[bearer_id]);
+	if (likely(b)) {
+		skb_queue_walk_safe(xmitq, skb, tmp) {
+			__skb_dequeue(xmitq);
+			b->media->send_msg(net, skb, b, dst);
+			/* Until we remove cloning in tipc_l2_send_msg(): */
+			kfree_skb(skb);
+		}
+	}
+	rcu_read_unlock();
+}
+
 /**
  * tipc_l2_rcv_msg - handle incoming TIPC message from an interface
  * @buf: the received packet