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Ignore irrelevant states on receiving feedback

PATCH In review Arnaldo Carvalho de Melo 1 participant 1 message Apr 12, 2007 Networking

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Arnaldo Carvalho de Melo

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PATCH 9/29 Ignore irrelevant states on receiving feedback

This removes two currently irrelevant states in TX feedback handling:

* the NO_SENT state is not triggered, since currently DCCP only operates in half-connections (in which this state is irrelevant). When upgrading to bidirectional half-connections, other changes are required anyhow, so that there is no loss in removing this currently unsupported state.

* the TERM (terminating) state is uninteresting.

Signed-off-by Gerrit Renker <[email protected]>
Signed-off-by Arnaldo Carvalho de Melo <[email protected]>
---
 net/dccp/ccids/ccid3.c |  207 ++++++++++++++++++++++++------------------------
 1 files changed, 102 insertions(+), 105 deletions(-)
net/dccp/ccids/ccid3.c +101 -104
index 9d661e4..22ba3f9 100644
@@ -442,130 +442,127 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 	      DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_DATAACK))
 		return;
 
+	/* only the established state is of interest here */
+	switch (hctx->ccid3hctx_state) {
+	case TFRC_SSTATE_NO_FBACK:	/* fall through */
+	case TFRC_SSTATE_FBACK:		break;
+	default:			return;
+	}
+
+	/* get packet from history to look up t_recvdata */
+	packet = dccp_tx_hist_find_entry(&hctx->ccid3hctx_hist,
+				         DCCP_SKB_CB(skb)->dccpd_ack_seq);
+	if (unlikely(packet = NULL)) {
+		DCCP_WARN("%s(%p), seqno %llu(%s) doesn't exist in history!\n",
+			  dccp_role(sk), sk,
+		          (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
+			  dccp_packet_name(DCCP_SKB_CB(skb)->dccpd_type));
+		return;
+	}
+
 	opt_recv = &hctx->ccid3hctx_options_received;
 
-	switch (hctx->ccid3hctx_state) {
-	case TFRC_SSTATE_NO_FBACK:
-	case TFRC_SSTATE_FBACK:
-		/* get packet from history to look up t_recvdata */
-		packet = dccp_tx_hist_find_entry(&hctx->ccid3hctx_hist,
-					      DCCP_SKB_CB(skb)->dccpd_ack_seq);
-		if (unlikely(packet = NULL)) {
-			DCCP_WARN("%s(%p), seqno %llu(%s) doesn't exist "
-				  "in history!\n",  dccp_role(sk), sk,
-			    (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
-				dccp_packet_name(DCCP_SKB_CB(skb)->dccpd_type));
-			return;
-		}
+	/* Update receive rate in units of 64 * bytes/second */
+	hctx->ccid3hctx_x_recv = opt_recv->ccid3or_receive_rate;
+	hctx->ccid3hctx_x_recv <<= 6;
 
-		/* Update receive rate in units of 64 * bytes/second */
-		hctx->ccid3hctx_x_recv = opt_recv->ccid3or_receive_rate;
-		hctx->ccid3hctx_x_recv <<= 6;
+	/* Update loss event rate */
+	pinv = opt_recv->ccid3or_loss_event_rate;
+	if (pinv = ~0U || pinv = 0)	       /* see RFC 4342, 8.5   */
+		hctx->ccid3hctx_p = 0;
+	else				       /* can not exceed 100% */
+		hctx->ccid3hctx_p = 1000000 / pinv;
 
-		/* Update loss event rate */
-		pinv = opt_recv->ccid3or_loss_event_rate;
-		if (pinv = ~0U || pinv = 0)	       /* see RFC 4342, 8.5   */
-			hctx->ccid3hctx_p = 0;
-		else				       /* can not exceed 100% */
-			hctx->ccid3hctx_p = 1000000 / pinv;
+	/*
+	 * Calculate new round trip sample as per [RFC 3448, 4.3] by
+	 * R_sample  =  (t_now - t_recvdata) - t_elapsed
+	 */
+	skb_get_timestamp(skb, &now);
+	r_sample = dccp_sample_rtt(sk, &now, &packet->dccphtx_tstamp);
 
-		/*
-		 * Calculate new round trip sample as per [RFC 3448, 4.3] by
-		 *	R_sample  =  (now - t_recvdata) - t_elapsed
-		 */
-		skb_get_timestamp(skb, &now);
-		r_sample = dccp_sample_rtt(sk, &now, &packet->dccphtx_tstamp);
+	/*
+	 * Update RTT estimate (honours RTT from SYN exchange):
+	 * If (No RTT sample so far)
+	 *    R = R_sample;
+	 * Else
+	 *    R = q * R + (1 - q) * R_sample;
+	 *
+	 * q is a constant, RFC 3448 recommends 0.9
+	 */
+	hctx->ccid3hctx_rtt = hctx->ccid3hctx_rtt = 0 ?  r_sample
+			    : (9 * hctx->ccid3hctx_rtt + r_sample) / 10;
 
+	if (hctx->ccid3hctx_state = TFRC_SSTATE_NO_FBACK) {
 		/*
-		 * Update RTT estimate (honours RTT from SYN exchange):
-		 * If (No RTT sample so far)
-		 *    R = R_sample;
-		 * Else
-		 *    R = q * R + (1 - q) * R_sample;
-		 *
-		 * q is a constant, RFC 3448 recomments 0.9
+		 * Larger Initial Windows [RFC 4342, sec. 5]
 		 */
-		hctx->ccid3hctx_rtt = hctx->ccid3hctx_rtt = 0 ?  r_sample
-				    : (9 * hctx->ccid3hctx_rtt + r_sample) / 10;
+		hctx->ccid3hctx_x    = rfc3390_initial_rate(sk);
+		hctx->ccid3hctx_t_ld = now;
 
-		if (hctx->ccid3hctx_state = TFRC_SSTATE_NO_FBACK) {
-			/*
-			 * Larger Initial Windows [RFC 4342, sec. 5]
-			 */
-			hctx->ccid3hctx_x    = rfc3390_initial_rate(sk);
-			hctx->ccid3hctx_t_ld = now;
+		ccid3_update_send_interval(hctx);
 
-			ccid3_update_send_interval(hctx);
+		ccid3_pr_debug("%s(%p), s=%u, MSS=%u, "
+			       "R_sample=%uus, X=%u\n", dccp_role(sk),
+			       sk, hctx->ccid3hctx_s,
+			       dp->dccps_mss_cache, r_sample,
+			       (unsigned)(hctx->ccid3hctx_x >> 6));
 
-			ccid3_pr_debug("%s(%p), s=%u, MSS=%u, "
-				       "R_sample=%uus, X=%u\n", dccp_role(sk),
-				       sk, hctx->ccid3hctx_s,
-				       dp->dccps_mss_cache, r_sample,
-				       (unsigned)(hctx->ccid3hctx_x >> 6));
+		ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
+	} else {
 
-			ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
-		} else {
+		/* Update sending rate (step 4 of [RFC 3448, 4.3]) */
+		if (hctx->ccid3hctx_p > 0)
+			hctx->ccid3hctx_x_calc +				tfrc_calc_x(hctx->ccid3hctx_s,
+					    hctx->ccid3hctx_rtt,
+					    hctx->ccid3hctx_p);
+		ccid3_hc_tx_update_x(sk, &now);
 
-			/* Update sending rate (step 4 of [RFC 3448, 4.3]) */
-			if (hctx->ccid3hctx_p > 0)
-				hctx->ccid3hctx_x_calc -					tfrc_calc_x(hctx->ccid3hctx_s,
-						    hctx->ccid3hctx_rtt,
-						    hctx->ccid3hctx_p);
-			ccid3_hc_tx_update_x(sk, &now);
-
-			ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
-				       "p=%u, X_calc=%u, X_recv=%u, X=%u\n",
-				       dccp_role(sk),
-				       sk, hctx->ccid3hctx_rtt, r_sample,
-				       hctx->ccid3hctx_s, hctx->ccid3hctx_p,
-				       hctx->ccid3hctx_x_calc,
-				       (unsigned)(hctx->ccid3hctx_x_recv >> 6),
-				       (unsigned)(hctx->ccid3hctx_x >> 6));
-		}
+		ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
+			       "p=%u, X_calc=%u, X_recv=%u, X=%u\n",
+			       dccp_role(sk),
+			       sk, hctx->ccid3hctx_rtt, r_sample,
+			       hctx->ccid3hctx_s, hctx->ccid3hctx_p,
+			       hctx->ccid3hctx_x_calc,
+			       (unsigned)(hctx->ccid3hctx_x_recv >> 6),
+			       (unsigned)(hctx->ccid3hctx_x >> 6));
+	}
 
-		/* unschedule no feedback timer */
-		sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);
+	/* unschedule no feedback timer */
+	sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);
 
-		/* remove all packets older than the one acked from history */
-		dccp_tx_hist_purge_older(ccid3_tx_hist,
-					 &hctx->ccid3hctx_hist, packet);
-		/*
-		 * As we have calculated new ipi, delta, t_nom it is possible
-		 * that we now can send a packet, so wake up dccp_wait_for_ccid
-		 */
-		sk->sk_write_space(sk);
+	/* remove all packets older than the one acked from history */
+	dccp_tx_hist_purge_older(ccid3_tx_hist,
+				 &hctx->ccid3hctx_hist, packet);
+	/*
+	 * As we have calculated new ipi, delta, t_nom it is possible
+	 * that we now can send a packet, so wake up dccp_wait_for_ccid
+	 */
+	sk->sk_write_space(sk);
 
-		/*
-		 * Update timeout interval for the nofeedback timer.
-		 * We use a configuration option to increase the lower bound.
-		 * This can help avoid triggering the nofeedback timer too
-		 * 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));
-		/*
-		 * Schedule no feedback timer to expire in
-		 * max(t_RTO, 2 * s/X)  =  max(t_RTO, 2 * t_ipi)
-		 */
-		t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi);
+	/*
+	 * Update timeout interval for the nofeedback timer.
+	 * We use a configuration option to increase the lower bound.
+	 * This can help avoid triggering the nofeedback timer too
+	 * 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));
+	/*
+	 * Schedule no feedback timer to expire in
+	 * max(t_RTO, 2 * s/X)  =  max(t_RTO, 2 * t_ipi)
+	 */
+	t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi);
 
-		ccid3_pr_debug("%s(%p), Scheduled no feedback timer to "
-			       "expire in %lu jiffies (%luus)\n",
-			       dccp_role(sk),
-			       sk, usecs_to_jiffies(t_nfb), t_nfb);
+	sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
+			   jiffies + usecs_to_jiffies(t_nfb));
 
-		sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
-				   jiffies + usecs_to_jiffies(t_nfb));
+	ccid3_pr_debug("Scheduled no feedback timer to expire in %lu jiffies"
+		       "(%luus)\n", usecs_to_jiffies(t_nfb), t_nfb);
 
-		/* set idle flag */
-		hctx->ccid3hctx_idle = 1;
-		break;
-	case TFRC_SSTATE_NO_SENT:	/* fall through */
-	case TFRC_SSTATE_TERM:		/* ignore feedback when closing */
-		break;
-	}
+	/* set idle flag */
+	hctx->ccid3hctx_idle = 1;
 }
 
 static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option,
Signature · 1 line
1.5.0.6