Commit 0c150efb authored by Gerrit Renker's avatar Gerrit Renker Committed by David S. Miller
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[CCID3]: Handle Idle and Application-Limited periods 

This updates the code with regard to handling idle and application-limited
periods as specified in [RFC 4342, 5.1].

Background:
parent a21f9f96

net/dccp/ccids/ccid3.c

+40 −44
Original line number Diff line number Diff line
@@ -133,12 +133,23 @@ static void ccid3_hc_tx_update_x(struct sock *sk, struct timeval *now) 


{

	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);

	__u64 min_rate = 2 * hctx->ccid3hctx_x_recv;

	const  __u64 old_x = hctx->ccid3hctx_x;



	/*

	 * Handle IDLE periods: do not reduce below RFC3390 initial sending rate

	 * when idling [RFC 4342, 5.1]. See also draft-ietf-dccp-rfc3448bis.

	 * For consistency with X and X_recv, min_rate is also scaled by 2^6.

	 */

	if (unlikely(hctx->ccid3hctx_idle)) {

		min_rate = rfc3390_initial_rate(sk);

		min_rate = max(min_rate, 2 * hctx->ccid3hctx_x_recv);

	}



	if (hctx->ccid3hctx_p > 0) {



		hctx->ccid3hctx_x = min(((__u64)hctx->ccid3hctx_x_calc) << 6,

					hctx->ccid3hctx_x_recv * 2);

					min_rate);

		hctx->ccid3hctx_x = max(hctx->ccid3hctx_x,

					(((__u64)hctx->ccid3hctx_s) << 6) /

								TFRC_T_MBI);
@@ -147,7 +158,7 @@ static void ccid3_hc_tx_update_x(struct sock *sk, struct timeval *now) 
			(suseconds_t)hctx->ccid3hctx_rtt >= 0) {



		hctx->ccid3hctx_x =

			max(2 * min(hctx->ccid3hctx_x, hctx->ccid3hctx_x_recv),

			max(min(2 * hctx->ccid3hctx_x, min_rate),

			    scaled_div(((__u64)hctx->ccid3hctx_s) << 6,

				       hctx->ccid3hctx_rtt));

		hctx->ccid3hctx_t_ld = *now;
@@ -209,6 +220,7 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data) 
{

	struct sock *sk = (struct sock *)data;

	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);

	struct timeval now;

	unsigned long t_nfb = USEC_PER_SEC / 5;



	bh_lock_sock(sk);
@@ -221,6 +233,8 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data) 
	ccid3_pr_debug("%s(%p, state=%s) - entry \n", dccp_role(sk), sk,

		       ccid3_tx_state_name(hctx->ccid3hctx_state));



	hctx->ccid3hctx_idle = 1;



	switch (hctx->ccid3hctx_state) {

	case TFRC_SSTATE_NO_FBACK:

		/* RFC 3448, 4.4: Halve send rate directly */
@@ -238,20 +252,6 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data) 
		ccid3_update_send_interval(hctx);

		break;

	case TFRC_SSTATE_FBACK:

		/*

		 * Check if IDLE since last timeout and recv rate is less than

		 * 4 packets (in units of 64*bytes/sec) per RTT

		 */

		if (!hctx->ccid3hctx_idle ||

		    (hctx->ccid3hctx_x_recv >= 4 *

		     scaled_div(((__u64)hctx->ccid3hctx_s) << 6,

				hctx->ccid3hctx_rtt))) {

			struct timeval now;



			ccid3_pr_debug("%s(%p, state=%s), not idle\n",

				       dccp_role(sk), sk,

				   ccid3_tx_state_name(hctx->ccid3hctx_state));



		/*

		 *  Modify the cached value of X_recv [RFC 3448, 4.4]

		 *
@@ -265,8 +265,7 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data) 
		BUG_ON(hctx->ccid3hctx_p && !hctx->ccid3hctx_x_calc);



		if (hctx->ccid3hctx_p == 0 ||

			    (hctx->ccid3hctx_x_calc >

			     (hctx->ccid3hctx_x_recv >> 5))) {

		    (hctx->ccid3hctx_x_calc > (hctx->ccid3hctx_x_recv >> 5))) {



			hctx->ccid3hctx_x_recv =

				max(hctx->ccid3hctx_x_recv / 2,
@@ -281,7 +280,6 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data) 
		}

		/* Now recalculate X [RFC 3448, 4.3, step (4)] */

		ccid3_hc_tx_update_x(sk, &now);

		}

		/*

		 * Schedule no feedback timer to expire in

		 * max(t_RTO, 2 * s/X)  =  max(t_RTO, 2 * t_ipi)
@@ -296,8 +294,6 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data) 
		goto out;

	}



	hctx->ccid3hctx_idle = 1;



restart_timer:

	sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,

			   jiffies + usecs_to_jiffies(t_nfb));
@@ -377,6 +373,7 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) 
	/* prepare to send now (add options etc.) */

	dp->dccps_hc_tx_insert_options = 1;

	DCCP_SKB_CB(skb)->dccpd_ccval = hctx->ccid3hctx_last_win_count;

	hctx->ccid3hctx_idle = 0;



	/* set the nominal send time for the next following packet */

	timeval_add_usecs(&hctx->ccid3hctx_t_nom, hctx->ccid3hctx_t_ipi);
@@ -407,7 +404,6 @@ static void ccid3_hc_tx_packet_sent(struct sock *sk, int more, 
	packet->dccphtx_seqno  = dccp_sk(sk)->dccps_gss;

	packet->dccphtx_rtt    = hctx->ccid3hctx_rtt;

	packet->dccphtx_sent   = 1;

	hctx->ccid3hctx_idle   = 0;

}



static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)