[CCID3]: Remove two irrelevant states in TX feedback handling

 * the NO_SENT state is only triggered in bidirectional mode,
   costing unnecessary processing.
 * the TERM (terminating) state is irrelevant.
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/ccids/ccid3.c

@@ -402,15 +402,15 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 	if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK ||
 	      DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK))
 		return;
+	/* ... and only in the established state */
+	if (hctx->ccid3hctx_state != TFRC_SSTATE_FBACK &&
+	    hctx->ccid3hctx_state != TFRC_SSTATE_NO_FBACK)
+		return;
 
 	opt_recv = &hctx->ccid3hctx_options_received;
-
-	switch (hctx->ccid3hctx_state) {
-	case TFRC_SSTATE_NO_FBACK:
-	case TFRC_SSTATE_FBACK:
 	now = ktime_get_real();
 
-		/* estimate RTT from history if ACK number is valid */
+	/* Estimate RTT from history if ACK number is valid */
 	r_sample = tfrc_tx_hist_rtt(hctx->ccid3hctx_hist,
 				    DCCP_SKB_CB(skb)->dccpd_ack_seq, now);
 	if (r_sample == 0) {
@@ -424,7 +424,7 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 	hctx->ccid3hctx_x_recv = opt_recv->ccid3or_receive_rate;
 	hctx->ccid3hctx_x_recv <<= 6;
 
-		/* Update loss event rate */
+	/* Update loss event rate (which is scaled by 1e6) */
 	pinv = opt_recv->ccid3or_loss_event_rate;
 	if (pinv == ~0U || pinv == 0)	       /* see RFC 4342, 8.5   */
 		hctx->ccid3hctx_p = 0;
@@ -488,8 +488,8 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 	 * often ('spinning') on LANs with small RTTs.
 	 */
 	hctx->ccid3hctx_t_rto = max_t(u32, 4 * hctx->ccid3hctx_rtt,
-						   CONFIG_IP_DCCP_CCID3_RTO *
-						   (USEC_PER_SEC/1000));
+					   (CONFIG_IP_DCCP_CCID3_RTO *
+					    (USEC_PER_SEC / 1000)));
 	/*
 	 * Schedule no feedback timer to expire in
 	 * max(t_RTO, 2 * s/X)  =  max(t_RTO, 2 * t_ipi)
@@ -503,11 +503,6 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 
 	sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
 			   jiffies + usecs_to_jiffies(t_nfb));
-		break;
-	case TFRC_SSTATE_NO_SENT:	/* fall through */
-	case TFRC_SSTATE_TERM:		/* ignore feedback when closing */
-		break;
-	}
 }
 
 static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option,