rxrpc: Improve skb tracing

Improve sk_buff tracing within AF_RXRPC by the following means:

 (1) Use an enum to note the event type rather than plain integers and use
     an array of event names rather than a big multi ?: list.

 (2) Distinguish Rx from Tx packets and account them separately.  This
     requires the call phase to be tracked so that we know what we might
     find in rxtx_buffer[].

 (3) Add a parameter to rxrpc_{new,see,get,free}_skb() to indicate the
     event type.

 (4) A pair of 'rotate' events are added to indicate packets that are about
     to be rotated out of the Rx and Tx windows.

 (5) A pair of 'lost' events are added, along with rxrpc_lose_skb() for
     packet loss injection recording.

Signed-off-by: David Howells <dhowells@redhat.com>
 
diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c
index 9e0725f..18276e7 100644
--- a/net/rxrpc/peer_event.c
+++ b/net/rxrpc/peer_event.c
@@ -155,11 +155,11 @@
 		_leave("UDP socket errqueue empty");
 		return;
 	}
-	rxrpc_new_skb(skb);
+	rxrpc_new_skb(skb, rxrpc_skb_rx_received);
 	serr = SKB_EXT_ERR(skb);
 	if (!skb->len && serr->ee.ee_origin == SO_EE_ORIGIN_TIMESTAMPING) {
 		_leave("UDP empty message");
-		rxrpc_free_skb(skb);
+		rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
 		return;
 	}
 
@@ -169,7 +169,7 @@
 		peer = NULL;
 	if (!peer) {
 		rcu_read_unlock();
-		rxrpc_free_skb(skb);
+		rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
 		_leave(" [no peer]");
 		return;
 	}
@@ -179,7 +179,7 @@
 	     serr->ee.ee_code == ICMP_FRAG_NEEDED)) {
 		rxrpc_adjust_mtu(peer, serr);
 		rcu_read_unlock();
-		rxrpc_free_skb(skb);
+		rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
 		rxrpc_put_peer(peer);
 		_leave(" [MTU update]");
 		return;
@@ -187,7 +187,7 @@
 
 	rxrpc_store_error(peer, serr);
 	rcu_read_unlock();
-	rxrpc_free_skb(skb);
+	rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
 
 	/* The ref we obtained is passed off to the work item */
 	rxrpc_queue_work(&peer->error_distributor);