dccp: Schedule an Ack when receiving timestamps

This schedules an Ack when receiving a timestamp, exploiting the
existing inet_csk_schedule_ack() function, saving one case in the
`dccp_ack_pending()' function.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

net/dccp/dccp.h

@@ -431,7 +431,7 @@ static inline void dccp_update_gss(struct sock *sk, u64 seq)
 static inline int dccp_ack_pending(const struct sock *sk)
 {
 	const struct dccp_sock *dp = dccp_sk(sk);
-	return dp->dccps_timestamp_echo != 0 ||
+	return
 #ifdef CONFIG_IP_DCCP_ACKVEC
 	       (dp->dccps_hc_rx_ackvec != NULL &&
 		dccp_ackvec_pending(dp->dccps_hc_rx_ackvec)) ||

net/dccp/options.c

@@ -163,6 +163,8 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
 				      dccp_role(sk), ntohl(opt_val),
 				      (unsigned long long)
 				      DCCP_SKB_CB(skb)->dccpd_ack_seq);
+			/* schedule an Ack in case this sender is quiescent */
+			inet_csk_schedule_ack(sk);
 			break;
 		case DCCPO_TIMESTAMP_ECHO:
 			if (len != 4 && len != 6 && len != 8)