[DCCP]: More debug information for dccp_wait_for_ccid

This adds more detail in the wait_for_ccid packet scheduling loop.
In particular, it informs about (i) when delay is used and (ii) why
a packet is discarded.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: NIan McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/dccp/output.c

@@ -194,6 +194,7 @@ static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb)
 		rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb);
 		if (rc <= 0)
 			break;
+		dccp_pr_debug("delayed send by %d msec\n", rc);
 		delay = msecs_to_jiffies(rc);
 		sk->sk_write_pending++;
 		release_sock(sk);
@@ -255,7 +256,7 @@ void dccp_write_xmit(struct sock *sk, int block)
 				DCCP_BUG("err=%d after ccid_hc_tx_packet_sent",
 					 err);
 		} else {
-			dccp_pr_debug("packet discarded\n");
+			dccp_pr_debug("packet discarded due to err=%d\n", err);
 			kfree_skb(skb);
 		}
 	}