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Commit d8d1252f authored by Gerrit Renker's avatar Gerrit Renker Committed by David S. Miller
Browse files

[CCID3]: Implement rfc3448bis changes to feedback reception 



This implements the algorithm to update the allowed sending rate X upon
receiving feedback packets, as described in draft rfc3448bis, 4.2/4.3.

Signed-off-by: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: default avatarIan McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5bd370a6

net/dccp/ccids/ccid3.c

+26 −21
Original line number Diff line number Diff line
@@ -429,30 +429,35 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) 
	if (pinv == ~0U || pinv == 0)	       /* see RFC 4342, 8.5   */

		hctx->ccid3hctx_p = 0;

	else				       /* can not exceed 100% */

		hctx->ccid3hctx_p = 1000000 / pinv;

		hctx->ccid3hctx_p = scaled_div(1, pinv);

	/*

	 * Validate new RTT sample and update moving average

	 */

	r_sample = dccp_sample_rtt(sk, r_sample);

	hctx->ccid3hctx_rtt = tfrc_ewma(hctx->ccid3hctx_rtt, r_sample, 9);



	/*

	 * Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3

	 */

	if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) {

		ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);



		if (hctx->ccid3hctx_t_rto == 0) {

			/*

		 * Larger Initial Windows [RFC 4342, sec. 5]

			 * Initial feedback packet: Larger Initial Windows (4.2)

			 */

			hctx->ccid3hctx_x    = rfc3390_initial_rate(sk);

			hctx->ccid3hctx_t_ld = now;



			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,

			       dccp_sk(sk)->dccps_mss_cache, r_sample,

			       (unsigned)(hctx->ccid3hctx_x >> 6));



		ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);

	} else {

			goto done_computing_x;

		} else if (hctx->ccid3hctx_p == 0) {

			/*

			 * First feedback after nofeedback timer expiry (4.3)

			 */

			goto done_computing_x;

		}

	}



	/* Update sending rate (step 4 of [RFC 3448, 4.3]) */

	if (hctx->ccid3hctx_p > 0)
@@ -462,6 +467,7 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) 
					    hctx->ccid3hctx_p);

	ccid3_hc_tx_update_x(sk, &now);



done_computing_x:

	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),
@@ -470,7 +476,6 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) 
			       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);