Initial import of modified Linux 2.6.28 tree

Original upstream URL:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git | branch linux-2.6.28.y

14 files changed, 3902 insertions, 0 deletions

diff --git a/net/dccp/ccids/Kconfig b/net/dccp/ccids/Kconfig
new file mode 100644
index 0000000..1227594
--- /dev/null
+++ b/net/dccp/ccids/Kconfig
@@ -0,0 +1,119 @@
+menu "DCCP CCIDs Configuration (EXPERIMENTAL)"
+	depends on EXPERIMENTAL
+
+config IP_DCCP_CCID2
+	tristate "CCID2 (TCP-Like) (EXPERIMENTAL)"
+	def_tristate IP_DCCP
+	select IP_DCCP_ACKVEC
+	---help---
+	  CCID 2, TCP-like Congestion Control, denotes Additive Increase,
+	  Multiplicative Decrease (AIMD) congestion control with behavior
+	  modelled directly on TCP, including congestion window, slow start,
+	  timeouts, and so forth [RFC 2581].  CCID 2 achieves maximum
+	  bandwidth over the long term, consistent with the use of end-to-end
+	  congestion control, but halves its congestion window in response to
+	  each congestion event.  This leads to the abrupt rate changes
+	  typical of TCP.  Applications should use CCID 2 if they prefer
+	  maximum bandwidth utilization to steadiness of rate.  This is often
+	  the case for applications that are not playing their data directly
+	  to the user.  For example, a hypothetical application that
+	  transferred files over DCCP, using application-level retransmissions
+	  for lost packets, would prefer CCID 2 to CCID 3.  On-line games may
+	  also prefer CCID 2.  See RFC 4341 for further details.
+
+	  CCID2 is the default CCID used by DCCP.
+
+config IP_DCCP_CCID2_DEBUG
+	  bool "CCID2 debugging messages"
+	  depends on IP_DCCP_CCID2
+	  ---help---
+	    Enable CCID2-specific debugging messages.
+
+	    When compiling CCID2 as a module, this debugging output can
+	    additionally be toggled by setting the ccid2_debug module
+	    parameter to 0 or 1.
+
+	    If in doubt, say N.
+
+config IP_DCCP_CCID3
+	tristate "CCID3 (TCP-Friendly) (EXPERIMENTAL)"
+	def_tristate IP_DCCP
+	select IP_DCCP_TFRC_LIB
+	---help---
+	  CCID 3 denotes TCP-Friendly Rate Control (TFRC), an equation-based
+	  rate-controlled congestion control mechanism.  TFRC is designed to
+	  be reasonably fair when competing for bandwidth with TCP-like flows,
+	  where a flow is "reasonably fair" if its sending rate is generally
+	  within a factor of two of the sending rate of a TCP flow under the
+	  same conditions.  However, TFRC has a much lower variation of
+	  throughput over time compared with TCP, which makes CCID 3 more
+	  suitable than CCID 2 for applications such streaming media where a
+	  relatively smooth sending rate is of importance.
+
+	  CCID 3 is further described in RFC 4342,
+	  http://www.ietf.org/rfc/rfc4342.txt
+
+	  The TFRC congestion control algorithms were initially described in
+	  RFC 3448.
+
+	  This text was extracted from RFC 4340 (sec. 10.2),
+	  http://www.ietf.org/rfc/rfc4340.txt
+	  
+	  To compile this CCID as a module, choose M here: the module will be
+	  called dccp_ccid3.
+
+	  If in doubt, say M.
+
+config IP_DCCP_CCID3_DEBUG
+	  bool "CCID3 debugging messages"
+	  depends on IP_DCCP_CCID3
+	  ---help---
+	    Enable CCID3-specific debugging messages.
+
+	    When compiling CCID3 as a module, this debugging output can
+	    additionally be toggled by setting the ccid3_debug module
+	    parameter to 0 or 1.
+
+	    If in doubt, say N.
+
+config IP_DCCP_CCID3_RTO
+	  int "Use higher bound for nofeedback timer"
+	  default 100
+	  depends on IP_DCCP_CCID3 && EXPERIMENTAL
+	  ---help---
+	    Use higher lower bound for nofeedback timer expiration.
+
+	    The TFRC nofeedback timer normally expires after the maximum of 4
+	    RTTs and twice the current send interval (RFC 3448, 4.3). On LANs
+	    with a small RTT this can mean a high processing load and reduced
+	    performance, since then the nofeedback timer is triggered very
+	    frequently.
+
+	    This option enables to set a higher lower bound for the nofeedback
+	    value. Values in units of milliseconds can be set here.
+
+	    A value of 0 disables this feature by enforcing the value specified
+	    in RFC 3448. The following values have been suggested as bounds for
+	    experimental use:
+	    	* 16-20ms to match the typical multimedia inter-frame interval
+	    	* 100ms as a reasonable compromise [default]
+	    	* 1000ms corresponds to the lower TCP RTO bound (RFC 2988, 2.4)
+
+	    The default of 100ms is a compromise between a large value for
+	    efficient DCCP implementations, and a small value to avoid disrupting
+	    the network in times of congestion.
+
+	    The purpose of the nofeedback timer is to slow DCCP down when there
+	    is serious network congestion: experimenting with larger values should
+	    therefore not be performed on WANs.
+
+config IP_DCCP_TFRC_LIB
+	tristate
+	default n
+
+config IP_DCCP_TFRC_DEBUG
+	bool
+	depends on IP_DCCP_TFRC_LIB
+	default y if IP_DCCP_CCID3_DEBUG
+
+endmenu
diff --git a/net/dccp/ccids/Makefile b/net/dccp/ccids/Makefile
new file mode 100644
index 0000000..438f20b
--- /dev/null
+++ b/net/dccp/ccids/Makefile
@@ -0,0 +1,9 @@
+obj-$(CONFIG_IP_DCCP_CCID3) += dccp_ccid3.o
+
+dccp_ccid3-y := ccid3.o
+
+obj-$(CONFIG_IP_DCCP_CCID2) += dccp_ccid2.o
+
+dccp_ccid2-y := ccid2.o
+
+obj-y += lib/
diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
new file mode 100644
index 0000000..9a43073
--- /dev/null
+++ b/net/dccp/ccids/ccid2.c
@@ -0,0 +1,805 @@
+/*
+ *  net/dccp/ccids/ccid2.c
+ *
+ *  Copyright (c) 2005, 2006 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
+ *
+ *  Changes to meet Linux coding standards, and DCCP infrastructure fixes.
+ *
+ *  Copyright (c) 2006 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/*
+ * This implementation should follow RFC 4341
+ */
+
+#include "../ccid.h"
+#include "../dccp.h"
+#include "ccid2.h"
+
+
+#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
+static int ccid2_debug;
+#define ccid2_pr_debug(format, a...)	DCCP_PR_DEBUG(ccid2_debug, format, ##a)
+
+static void ccid2_hc_tx_check_sanity(const struct ccid2_hc_tx_sock *hctx)
+{
+	int len = 0;
+	int pipe = 0;
+	struct ccid2_seq *seqp = hctx->ccid2hctx_seqh;
+
+	/* there is data in the chain */
+	if (seqp != hctx->ccid2hctx_seqt) {
+		seqp = seqp->ccid2s_prev;
+		len++;
+		if (!seqp->ccid2s_acked)
+			pipe++;
+
+		while (seqp != hctx->ccid2hctx_seqt) {
+			struct ccid2_seq *prev = seqp->ccid2s_prev;
+
+			len++;
+			if (!prev->ccid2s_acked)
+				pipe++;
+
+			/* packets are sent sequentially */
+			BUG_ON(dccp_delta_seqno(seqp->ccid2s_seq,
+						prev->ccid2s_seq ) >= 0);
+			BUG_ON(time_before(seqp->ccid2s_sent,
+					   prev->ccid2s_sent));
+
+			seqp = prev;
+		}
+	}
+
+	BUG_ON(pipe != hctx->ccid2hctx_pipe);
+	ccid2_pr_debug("len of chain=%d\n", len);
+
+	do {
+		seqp = seqp->ccid2s_prev;
+		len++;
+	} while (seqp != hctx->ccid2hctx_seqh);
+
+	ccid2_pr_debug("total len=%d\n", len);
+	BUG_ON(len != hctx->ccid2hctx_seqbufc * CCID2_SEQBUF_LEN);
+}
+#else
+#define ccid2_pr_debug(format, a...)
+#define ccid2_hc_tx_check_sanity(hctx)
+#endif
+
+static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hctx)
+{
+	struct ccid2_seq *seqp;
+	int i;
+
+	/* check if we have space to preserve the pointer to the buffer */
+	if (hctx->ccid2hctx_seqbufc >= (sizeof(hctx->ccid2hctx_seqbuf) /
+					sizeof(struct ccid2_seq*)))
+		return -ENOMEM;
+
+	/* allocate buffer and initialize linked list */
+	seqp = kmalloc(CCID2_SEQBUF_LEN * sizeof(struct ccid2_seq), gfp_any());
+	if (seqp == NULL)
+		return -ENOMEM;
+
+	for (i = 0; i < (CCID2_SEQBUF_LEN - 1); i++) {
+		seqp[i].ccid2s_next = &seqp[i + 1];
+		seqp[i + 1].ccid2s_prev = &seqp[i];
+	}
+	seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = seqp;
+	seqp->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
+
+	/* This is the first allocation.  Initiate the head and tail.  */
+	if (hctx->ccid2hctx_seqbufc == 0)
+		hctx->ccid2hctx_seqh = hctx->ccid2hctx_seqt = seqp;
+	else {
+		/* link the existing list with the one we just created */
+		hctx->ccid2hctx_seqh->ccid2s_next = seqp;
+		seqp->ccid2s_prev = hctx->ccid2hctx_seqh;
+
+		hctx->ccid2hctx_seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
+		seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hctx->ccid2hctx_seqt;
+	}
+
+	/* store the original pointer to the buffer so we can free it */
+	hctx->ccid2hctx_seqbuf[hctx->ccid2hctx_seqbufc] = seqp;
+	hctx->ccid2hctx_seqbufc++;
+
+	return 0;
+}
+
+static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
+{
+	struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+
+	if (hctx->ccid2hctx_pipe < hctx->ccid2hctx_cwnd)
+		return 0;
+
+	return 1; /* XXX CCID should dequeue when ready instead of polling */
+}
+
+static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
+{
+	struct dccp_sock *dp = dccp_sk(sk);
+	u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->ccid2hctx_cwnd, 2);
+
+	/*
+	 * Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from
+	 * RFC 4341, 6.1.2. We ignore the statement that Ack Ratio 2 is always
+	 * acceptable since this causes starvation/deadlock whenever cwnd < 2.
+	 * The same problem arises when Ack Ratio is 0 (ie. Ack Ratio disabled).
+	 */
+	if (val == 0 || val > max_ratio) {
+		DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio);
+		val = max_ratio;
+	}
+	if (val > 0xFFFF)		/* RFC 4340, 11.3 */
+		val = 0xFFFF;
+
+	if (val == dp->dccps_l_ack_ratio)
+		return;
+
+	ccid2_pr_debug("changing local ack ratio to %u\n", val);
+	dp->dccps_l_ack_ratio = val;
+}
+
+static void ccid2_change_srtt(struct ccid2_hc_tx_sock *hctx, long val)
+{
+	ccid2_pr_debug("change SRTT to %ld\n", val);
+	hctx->ccid2hctx_srtt = val;
+}
+
+static void ccid2_start_rto_timer(struct sock *sk);
+
+static void ccid2_hc_tx_rto_expire(unsigned long data)
+{
+	struct sock *sk = (struct sock *)data;
+	struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+	long s;
+
+	bh_lock_sock(sk);
+	if (sock_owned_by_user(sk)) {
+		sk_reset_timer(sk, &hctx->ccid2hctx_rtotimer,
+			       jiffies + HZ / 5);
+		goto out;
+	}
+
+	ccid2_pr_debug("RTO_EXPIRE\n");
+
+	ccid2_hc_tx_check_sanity(hctx);
+
+	/* back-off timer */
+	hctx->ccid2hctx_rto <<= 1;
+
+	s = hctx->ccid2hctx_rto / HZ;
+	if (s > 60)
+		hctx->ccid2hctx_rto = 60 * HZ;
+
+	ccid2_start_rto_timer(sk);
+
+	/* adjust pipe, cwnd etc */
+	hctx->ccid2hctx_ssthresh = hctx->ccid2hctx_cwnd / 2;
+	if (hctx->ccid2hctx_ssthresh < 2)
+		hctx->ccid2hctx_ssthresh = 2;
+	hctx->ccid2hctx_cwnd	 = 1;
+	hctx->ccid2hctx_pipe	 = 0;
+
+	/* clear state about stuff we sent */
+	hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqh;
+	hctx->ccid2hctx_packets_acked = 0;
+
+	/* clear ack ratio state. */
+	hctx->ccid2hctx_rpseq	 = 0;
+	hctx->ccid2hctx_rpdupack = -1;
+	ccid2_change_l_ack_ratio(sk, 1);
+	ccid2_hc_tx_check_sanity(hctx);
+out:
+	bh_unlock_sock(sk);
+	sock_put(sk);
+}
+
+static void ccid2_start_rto_timer(struct sock *sk)
+{
+	struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+
+	ccid2_pr_debug("setting RTO timeout=%ld\n", hctx->ccid2hctx_rto);
+
+	BUG_ON(timer_pending(&hctx->ccid2hctx_rtotimer));
+	sk_reset_timer(sk, &hctx->ccid2hctx_rtotimer,
+		       jiffies + hctx->ccid2hctx_rto);
+}
+
+static void ccid2_hc_tx_packet_sent(struct sock *sk, int more, unsigned int len)
+{
+	struct dccp_sock *dp = dccp_sk(sk);
+	struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+	struct ccid2_seq *next;
+
+	hctx->ccid2hctx_pipe++;
+
+	hctx->ccid2hctx_seqh->ccid2s_seq   = dp->dccps_gss;
+	hctx->ccid2hctx_seqh->ccid2s_acked = 0;
+	hctx->ccid2hctx_seqh->ccid2s_sent  = jiffies;
+
+	next = hctx->ccid2hctx_seqh->ccid2s_next;
+	/* check if we need to alloc more space */
+	if (next == hctx->ccid2hctx_seqt) {
+		if (ccid2_hc_tx_alloc_seq(hctx)) {
+			DCCP_CRIT("packet history - out of memory!");
+			/* FIXME: find a more graceful way to bail out */
+			return;
+		}
+		next = hctx->ccid2hctx_seqh->ccid2s_next;
+		BUG_ON(next == hctx->ccid2hctx_seqt);
+	}
+	hctx->ccid2hctx_seqh = next;
+
+	ccid2_pr_debug("cwnd=%d pipe=%d\n", hctx->ccid2hctx_cwnd,
+		       hctx->ccid2hctx_pipe);
+
+	/*
+	 * FIXME: The code below is broken and the variables have been removed
+	 * from the socket struct. The `ackloss' variable was always set to 0,
+	 * and with arsent there are several problems:
+	 *  (i) it doesn't just count the number of Acks, but all sent packets;
+	 *  (ii) it is expressed in # of packets, not # of windows, so the
+	 *  comparison below uses the wrong formula: Appendix A of RFC 4341
+	 *  comes up with the number K = cwnd / (R^2 - R) of consecutive windows
+	 *  of data with no lost or marked Ack packets. If arsent were the # of
+	 *  consecutive Acks received without loss, then Ack Ratio needs to be
+	 *  decreased by 1 when
+	 *	      arsent >=  K * cwnd / R  =  cwnd^2 / (R^3 - R^2)
+	 *  where cwnd / R is the number of Acks received per window of data
+	 *  (cf. RFC 4341, App. A). The problems are that
+	 *  - arsent counts other packets as well;
+	 *  - the comparison uses a formula different from RFC 4341;
+	 *  - computing a cubic/quadratic equation each time is too complicated.
+	 *  Hence a different algorithm is needed.
+	 */
+#if 0
+	/* Ack Ratio.  Need to maintain a concept of how many windows we sent */
+	hctx->ccid2hctx_arsent++;
+	/* We had an ack loss in this window... */
+	if (hctx->ccid2hctx_ackloss) {
+		if (hctx->ccid2hctx_arsent >= hctx->ccid2hctx_cwnd) {
+			hctx->ccid2hctx_arsent	= 0;
+			hctx->ccid2hctx_ackloss	= 0;
+		}
+	} else {
+		/* No acks lost up to now... */
+		/* decrease ack ratio if enough packets were sent */
+		if (dp->dccps_l_ack_ratio > 1) {
+			/* XXX don't calculate denominator each time */
+			int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio -
+				    dp->dccps_l_ack_ratio;
+
+			denom = hctx->ccid2hctx_cwnd * hctx->ccid2hctx_cwnd / denom;
+
+			if (hctx->ccid2hctx_arsent >= denom) {
+				ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1);
+				hctx->ccid2hctx_arsent = 0;
+			}
+		} else {
+			/* we can't increase ack ratio further [1] */
+			hctx->ccid2hctx_arsent = 0; /* or maybe set it to cwnd*/
+		}
+	}
+#endif
+
+	/* setup RTO timer */
+	if (!timer_pending(&hctx->ccid2hctx_rtotimer))
+		ccid2_start_rto_timer(sk);
+
+#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
+	do {
+		struct ccid2_seq *seqp = hctx->ccid2hctx_seqt;
+
+		while (seqp != hctx->ccid2hctx_seqh) {
+			ccid2_pr_debug("out seq=%llu acked=%d time=%lu\n",
+				       (unsigned long long)seqp->ccid2s_seq,
+				       seqp->ccid2s_acked, seqp->ccid2s_sent);
+			seqp = seqp->ccid2s_next;
+		}
+	} while (0);
+	ccid2_pr_debug("=========\n");
+	ccid2_hc_tx_check_sanity(hctx);
+#endif
+}
+
+/* XXX Lame code duplication!
+ * returns -1 if none was found.
+ * else returns the next offset to use in the function call.
+ */
+static int ccid2_ackvector(struct sock *sk, struct sk_buff *skb, int offset,
+			   unsigned char **vec, unsigned char *veclen)
+{
+	const struct dccp_hdr *dh = dccp_hdr(skb);
+	unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
+	unsigned char *opt_ptr;
+	const unsigned char *opt_end = (unsigned char *)dh +
+					(dh->dccph_doff * 4);
+	unsigned char opt, len;
+	unsigned char *value;
+
+	BUG_ON(offset < 0);
+	options += offset;
+	opt_ptr = options;
+	if (opt_ptr >= opt_end)
+		return -1;
+
+	while (opt_ptr != opt_end) {
+		opt   = *opt_ptr++;
+		len   = 0;
+		value = NULL;
+
+		/* Check if this isn't a single byte option */
+		if (opt > DCCPO_MAX_RESERVED) {
+			if (opt_ptr == opt_end)
+				goto out_invalid_option;
+
+			len = *opt_ptr++;
+			if (len < 3)
+				goto out_invalid_option;
+			/*
+			 * Remove the type and len fields, leaving
+			 * just the value size
+			 */
+			len     -= 2;
+			value   = opt_ptr;
+			opt_ptr += len;
+
+			if (opt_ptr > opt_end)
+				goto out_invalid_option;
+		}
+
+		switch (opt) {
+		case DCCPO_ACK_VECTOR_0:
+		case DCCPO_ACK_VECTOR_1:
+			*vec	= value;
+			*veclen = len;
+			return offset + (opt_ptr - options);
+		}
+	}
+
+	return -1;
+
+out_invalid_option:
+	DCCP_BUG("Invalid option - this should not happen (previous parsing)!");
+	return -1;
+}
+
+static void ccid2_hc_tx_kill_rto_timer(struct sock *sk)
+{
+	struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+
+	sk_stop_timer(sk, &hctx->ccid2hctx_rtotimer);
+	ccid2_pr_debug("deleted RTO timer\n");
+}
+
+static inline void ccid2_new_ack(struct sock *sk,
+				 struct ccid2_seq *seqp,
+				 unsigned int *maxincr)
+{
+	struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+
+	if (hctx->ccid2hctx_cwnd < hctx->ccid2hctx_ssthresh) {
+		if (*maxincr > 0 && ++hctx->ccid2hctx_packets_acked == 2) {
+			hctx->ccid2hctx_cwnd += 1;
+			*maxincr	     -= 1;
+			hctx->ccid2hctx_packets_acked = 0;
+		}
+	} else if (++hctx->ccid2hctx_packets_acked >= hctx->ccid2hctx_cwnd) {
+			hctx->ccid2hctx_cwnd += 1;
+			hctx->ccid2hctx_packets_acked = 0;
+	}
+
+	/* update RTO */
+	if (hctx->ccid2hctx_srtt == -1 ||
+	    time_after(jiffies, hctx->ccid2hctx_lastrtt + hctx->ccid2hctx_srtt)) {
+		unsigned long r = (long)jiffies - (long)seqp->ccid2s_sent;
+		int s;
+
+		/* first measurement */
+		if (hctx->ccid2hctx_srtt == -1) {
+			ccid2_pr_debug("R: %lu Time=%lu seq=%llu\n",
+				       r, jiffies,
+				       (unsigned long long)seqp->ccid2s_seq);
+			ccid2_change_srtt(hctx, r);
+			hctx->ccid2hctx_rttvar = r >> 1;
+		} else {
+			/* RTTVAR */
+			long tmp = hctx->ccid2hctx_srtt - r;
+			long srtt;
+
+			if (tmp < 0)
+				tmp *= -1;
+
+			tmp >>= 2;
+			hctx->ccid2hctx_rttvar *= 3;
+			hctx->ccid2hctx_rttvar >>= 2;
+			hctx->ccid2hctx_rttvar += tmp;
+
+			/* SRTT */
+			srtt = hctx->ccid2hctx_srtt;
+			srtt *= 7;
+			srtt >>= 3;
+			tmp = r >> 3;
+			srtt += tmp;
+			ccid2_change_srtt(hctx, srtt);
+		}
+		s = hctx->ccid2hctx_rttvar << 2;
+		/* clock granularity is 1 when based on jiffies */
+		if (!s)
+			s = 1;
+		hctx->ccid2hctx_rto = hctx->ccid2hctx_srtt + s;
+
+		/* must be at least a second */
+		s = hctx->ccid2hctx_rto / HZ;
+		/* DCCP doesn't require this [but I like it cuz my code sux] */
+#if 1
+		if (s < 1)
+			hctx->ccid2hctx_rto = HZ;
+#endif
+		/* max 60 seconds */
+		if (s > 60)
+			hctx->ccid2hctx_rto = HZ * 60;
+
+		hctx->ccid2hctx_lastrtt = jiffies;
+
+		ccid2_pr_debug("srtt: %ld rttvar: %ld rto: %ld (HZ=%d) R=%lu\n",
+			       hctx->ccid2hctx_srtt, hctx->ccid2hctx_rttvar,
+			       hctx->ccid2hctx_rto, HZ, r);
+	}
+
+	/* we got a new ack, so re-start RTO timer */
+	ccid2_hc_tx_kill_rto_timer(sk);
+	ccid2_start_rto_timer(sk);
+}
+
+static void ccid2_hc_tx_dec_pipe(struct sock *sk)
+{
+	struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+
+	if (hctx->ccid2hctx_pipe == 0)
+		DCCP_BUG("pipe == 0");
+	else
+		hctx->ccid2hctx_pipe--;
+
+	if (hctx->ccid2hctx_pipe == 0)
+		ccid2_hc_tx_kill_rto_timer(sk);
+}
+
+static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
+{
+	struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+
+	if (time_before(seqp->ccid2s_sent, hctx->ccid2hctx_last_cong)) {
+		ccid2_pr_debug("Multiple losses in an RTT---treating as one\n");
+		return;
+	}
+
+	hctx->ccid2hctx_last_cong = jiffies;
+
+	hctx->ccid2hctx_cwnd     = hctx->ccid2hctx_cwnd / 2 ? : 1U;
+	hctx->ccid2hctx_ssthresh = max(hctx->ccid2hctx_cwnd, 2U);
+
+	/* Avoid spurious timeouts resulting from Ack Ratio > cwnd */
+	if (dccp_sk(sk)->dccps_l_ack_ratio > hctx->ccid2hctx_cwnd)
+		ccid2_change_l_ack_ratio(sk, hctx->ccid2hctx_cwnd);
+}
+
+static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
+{
+	struct dccp_sock *dp = dccp_sk(sk);
+	struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+	u64 ackno, seqno;
+	struct ccid2_seq *seqp;
+	unsigned char *vector;
+	unsigned char veclen;
+	int offset = 0;
+	int done = 0;
+	unsigned int maxincr = 0;
+
+	ccid2_hc_tx_check_sanity(hctx);
+	/* check reverse path congestion */
+	seqno = DCCP_SKB_CB(skb)->dccpd_seq;
+
+	/* XXX this whole "algorithm" is broken.  Need to fix it to keep track
+	 * of the seqnos of the dupacks so that rpseq and rpdupack are correct
+	 * -sorbo.
+	 */
+	/* need to bootstrap */
+	if (hctx->ccid2hctx_rpdupack == -1) {
+		hctx->ccid2hctx_rpdupack = 0;
+		hctx->ccid2hctx_rpseq = seqno;
+	} else {
+		/* check if packet is consecutive */
+		if (dccp_delta_seqno(hctx->ccid2hctx_rpseq, seqno) == 1)
+			hctx->ccid2hctx_rpseq = seqno;
+		/* it's a later packet */
+		else if (after48(seqno, hctx->ccid2hctx_rpseq)) {
+			hctx->ccid2hctx_rpdupack++;
+
+			/* check if we got enough dupacks */
+			if (hctx->ccid2hctx_rpdupack >= NUMDUPACK) {
+				hctx->ccid2hctx_rpdupack = -1; /* XXX lame */
+				hctx->ccid2hctx_rpseq = 0;
+
+				ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio);
+			}
+		}
+	}
+
+	/* check forward path congestion */
+	/* still didn't send out new data packets */
+	if (hctx->ccid2hctx_seqh == hctx->ccid2hctx_seqt)
+		return;
+
+	switch (DCCP_SKB_CB(skb)->dccpd_type) {
+	case DCCP_PKT_ACK:
+	case DCCP_PKT_DATAACK:
+		break;
+	default:
+		return;
+	}
+
+	ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
+	if (after48(ackno, hctx->ccid2hctx_high_ack))
+		hctx->ccid2hctx_high_ack = ackno;
+
+	seqp = hctx->ccid2hctx_seqt;
+	while (before48(seqp->ccid2s_seq, ackno)) {
+		seqp = seqp->ccid2s_next;
+		if (seqp == hctx->ccid2hctx_seqh) {
+			seqp = hctx->ccid2hctx_seqh->ccid2s_prev;
+			break;
+		}
+	}
+
+	/*
+	 * In slow-start, cwnd can increase up to a maximum of Ack Ratio/2
+	 * packets per acknowledgement. Rounding up avoids that cwnd is not
+	 * advanced when Ack Ratio is 1 and gives a slight edge otherwise.
+	 */
+	if (hctx->ccid2hctx_cwnd < hctx->ccid2hctx_ssthresh)
+		maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2);
+
+	/* go through all ack vectors */
+	while ((offset = ccid2_ackvector(sk, skb, offset,
+					 &vector, &veclen)) != -1) {
+		/* go through this ack vector */
+		while (veclen--) {
+			const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
+			u64 ackno_end_rl = SUB48(ackno, rl);
+
+			ccid2_pr_debug("ackvec start:%llu end:%llu\n",
+				       (unsigned long long)ackno,
+				       (unsigned long long)ackno_end_rl);
+			/* if the seqno we are analyzing is larger than the
+			 * current ackno, then move towards the tail of our
+			 * seqnos.
+			 */
+			while (after48(seqp->ccid2s_seq, ackno)) {
+				if (seqp == hctx->ccid2hctx_seqt) {
+					done = 1;
+					break;
+				}
+				seqp = seqp->ccid2s_prev;
+			}
+			if (done)
+				break;
+
+			/* check all seqnos in the range of the vector
+			 * run length
+			 */
+			while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) {
+				const u8 state = *vector &
+						 DCCP_ACKVEC_STATE_MASK;
+
+				/* new packet received or marked */
+				if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED &&
+				    !seqp->ccid2s_acked) {
+					if (state ==
+					    DCCP_ACKVEC_STATE_ECN_MARKED) {
+						ccid2_congestion_event(sk,
+								       seqp);
+					} else
+						ccid2_new_ack(sk, seqp,
+							      &maxincr);
+
+					seqp->ccid2s_acked = 1;
+					ccid2_pr_debug("Got ack for %llu\n",
+						       (unsigned long long)seqp->ccid2s_seq);
+					ccid2_hc_tx_dec_pipe(sk);
+				}
+				if (seqp == hctx->ccid2hctx_seqt) {
+					done = 1;
+					break;
+				}
+				seqp = seqp->ccid2s_prev;
+			}
+			if (done)
+				break;
+
+			ackno = SUB48(ackno_end_rl, 1);
+			vector++;
+		}
+		if (done)
+			break;
+	}
+
+	/* The state about what is acked should be correct now
+	 * Check for NUMDUPACK
+	 */
+	seqp = hctx->ccid2hctx_seqt;
+	while (before48(seqp->ccid2s_seq, hctx->ccid2hctx_high_ack)) {
+		seqp = seqp->ccid2s_next;
+		if (seqp == hctx->ccid2hctx_seqh) {
+			seqp = hctx->ccid2hctx_seqh->ccid2s_prev;
+			break;
+		}
+	}
+	done = 0;
+	while (1) {
+		if (seqp->ccid2s_acked) {
+			done++;
+			if (done == NUMDUPACK)
+				break;
+		}
+		if (seqp == hctx->ccid2hctx_seqt)
+			break;
+		seqp = seqp->ccid2s_prev;
+	}
+
+	/* If there are at least 3 acknowledgements, anything unacknowledged
+	 * below the last sequence number is considered lost
+	 */
+	if (done == NUMDUPACK) {
+		struct ccid2_seq *last_acked = seqp;
+
+		/* check for lost packets */
+		while (1) {
+			if (!seqp->ccid2s_acked) {
+				ccid2_pr_debug("Packet lost: %llu\n",
+					       (unsigned long long)seqp->ccid2s_seq);
+				/* XXX need to traverse from tail -> head in
+				 * order to detect multiple congestion events in
+				 * one ack vector.
+				 */
+				ccid2_congestion_event(sk, seqp);
+				ccid2_hc_tx_dec_pipe(sk);
+			}
+			if (seqp == hctx->ccid2hctx_seqt)
+				break;
+			seqp = seqp->ccid2s_prev;
+		}
+
+		hctx->ccid2hctx_seqt = last_acked;
+	}
+
+	/* trim acked packets in tail */
+	while (hctx->ccid2hctx_seqt != hctx->ccid2hctx_seqh) {
+		if (!hctx->ccid2hctx_seqt->ccid2s_acked)
+			break;
+
+		hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqt->ccid2s_next;
+	}
+
+	ccid2_hc_tx_check_sanity(hctx);
+}
+
+static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
+{
+	struct ccid2_hc_tx_sock *hctx = ccid_priv(ccid);
+	struct dccp_sock *dp = dccp_sk(sk);
+	u32 max_ratio;
+
+	/* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */
+	hctx->ccid2hctx_ssthresh  = ~0U;
+
+	/*
+	 * RFC 4341, 5: "The cwnd parameter is initialized to at most four
+	 * packets for new connections, following the rules from [RFC3390]".
+	 * We need to convert the bytes of RFC3390 into the packets of RFC 4341.
+	 */
+	hctx->ccid2hctx_cwnd = clamp(4380U / dp->dccps_mss_cache, 2U, 4U);
+
+	/* Make sure that Ack Ratio is enabled and within bounds. */
+	max_ratio = DIV_ROUND_UP(hctx->ccid2hctx_cwnd, 2);
+	if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio)
+		dp->dccps_l_ack_ratio = max_ratio;
+
+	/* XXX init ~ to window size... */
+	if (ccid2_hc_tx_alloc_seq(hctx))
+		return -ENOMEM;
+
+	hctx->ccid2hctx_rto	 = 3 * HZ;
+	ccid2_change_srtt(hctx, -1);
+	hctx->ccid2hctx_rttvar	 = -1;
+	hctx->ccid2hctx_rpdupack = -1;
+	hctx->ccid2hctx_last_cong = jiffies;
+	setup_timer(&hctx->ccid2hctx_rtotimer, ccid2_hc_tx_rto_expire,
+			(unsigned long)sk);
+
+	ccid2_hc_tx_check_sanity(hctx);
+	return 0;
+}
+
+static void ccid2_hc_tx_exit(struct sock *sk)
+{
+	struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+	int i;
+
+	ccid2_hc_tx_kill_rto_timer(sk);
+
+	for (i = 0; i < hctx->ccid2hctx_seqbufc; i++)
+		kfree(hctx->ccid2hctx_seqbuf[i]);
+	hctx->ccid2hctx_seqbufc = 0;
+}
+
+static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
+{
+	const struct dccp_sock *dp = dccp_sk(sk);
+	struct ccid2_hc_rx_sock *hcrx = ccid2_hc_rx_sk(sk);
+
+	switch (DCCP_SKB_CB(skb)->dccpd_type) {
+	case DCCP_PKT_DATA:
+	case DCCP_PKT_DATAACK:
+		hcrx->ccid2hcrx_data++;
+		if (hcrx->ccid2hcrx_data >= dp->dccps_r_ack_ratio) {
+			dccp_send_ack(sk);
+			hcrx->ccid2hcrx_data = 0;
+		}
+		break;
+	}
+}
+
+static struct ccid_operations ccid2 = {
+	.ccid_id		= DCCPC_CCID2,
+	.ccid_name		= "TCP-like",
+	.ccid_owner		= THIS_MODULE,
+	.ccid_hc_tx_obj_size	= sizeof(struct ccid2_hc_tx_sock),
+	.ccid_hc_tx_init	= ccid2_hc_tx_init,
+	.ccid_hc_tx_exit	= ccid2_hc_tx_exit,
+	.ccid_hc_tx_send_packet	= ccid2_hc_tx_send_packet,
+	.ccid_hc_tx_packet_sent	= ccid2_hc_tx_packet_sent,
+	.ccid_hc_tx_packet_recv	= ccid2_hc_tx_packet_recv,
+	.ccid_hc_rx_obj_size	= sizeof(struct ccid2_hc_rx_sock),
+	.ccid_hc_rx_packet_recv	= ccid2_hc_rx_packet_recv,
+};
+
+#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
+module_param(ccid2_debug, bool, 0644);
+MODULE_PARM_DESC(ccid2_debug, "Enable debug messages");
+#endif
+
+static __init int ccid2_module_init(void)
+{
+	return ccid_register(&ccid2);
+}
+module_init(ccid2_module_init);
+
+static __exit void ccid2_module_exit(void)
+{
+	ccid_unregister(&ccid2);
+}
+module_exit(ccid2_module_exit);
+
+MODULE_AUTHOR("Andrea Bittau <a.bittau@cs.ucl.ac.uk>");
+MODULE_DESCRIPTION("DCCP TCP-Like (CCID2) CCID");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("net-dccp-ccid-2");
diff --git a/net/dccp/ccids/ccid2.h b/net/dccp/ccids/ccid2.h
new file mode 100644
index 0000000..2c94ca0
--- /dev/null
+++ b/net/dccp/ccids/ccid2.h
@@ -0,0 +1,84 @@
+/*
+ *  net/dccp/ccids/ccid2.h
+ *
+ *  Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#ifndef _DCCP_CCID2_H_
+#define _DCCP_CCID2_H_
+
+#include <linux/dccp.h>
+#include <linux/timer.h>
+#include <linux/types.h>
+#include "../ccid.h"
+/* NUMDUPACK parameter from RFC 4341, p. 6 */
+#define NUMDUPACK	3
+
+struct sock;
+
+struct ccid2_seq {
+	u64			ccid2s_seq;
+	unsigned long		ccid2s_sent;
+	int			ccid2s_acked;
+	struct ccid2_seq	*ccid2s_prev;
+	struct ccid2_seq	*ccid2s_next;
+};
+
+#define CCID2_SEQBUF_LEN 1024
+#define CCID2_SEQBUF_MAX 128
+
+/** struct ccid2_hc_tx_sock - CCID2 TX half connection
+ *
+ * @ccid2hctx_{cwnd,ssthresh,pipe}: as per RFC 4341, section 5
+ * @ccid2hctx_packets_acked - Ack counter for deriving cwnd growth (RFC 3465)
+ * @ccid2hctx_lastrtt -time RTT was last measured
+ * @ccid2hctx_rpseq - last consecutive seqno
+ * @ccid2hctx_rpdupack - dupacks since rpseq
+*/
+struct ccid2_hc_tx_sock {
+	u32			ccid2hctx_cwnd;
+	u32			ccid2hctx_ssthresh;
+	u32			ccid2hctx_pipe;
+	u32			ccid2hctx_packets_acked;
+	struct ccid2_seq	*ccid2hctx_seqbuf[CCID2_SEQBUF_MAX];
+	int			ccid2hctx_seqbufc;
+	struct ccid2_seq	*ccid2hctx_seqh;
+	struct ccid2_seq	*ccid2hctx_seqt;
+	long			ccid2hctx_rto;
+	long			ccid2hctx_srtt;
+	long			ccid2hctx_rttvar;
+	unsigned long		ccid2hctx_lastrtt;
+	struct timer_list	ccid2hctx_rtotimer;
+	u64			ccid2hctx_rpseq;
+	int			ccid2hctx_rpdupack;
+	unsigned long		ccid2hctx_last_cong;
+	u64			ccid2hctx_high_ack;
+};
+
+struct ccid2_hc_rx_sock {
+	int	ccid2hcrx_data;
+};
+
+static inline struct ccid2_hc_tx_sock *ccid2_hc_tx_sk(const struct sock *sk)
+{
+	return ccid_priv(dccp_sk(sk)->dccps_hc_tx_ccid);
+}
+
+static inline struct ccid2_hc_rx_sock *ccid2_hc_rx_sk(const struct sock *sk)
+{
+	return ccid_priv(dccp_sk(sk)->dccps_hc_rx_ccid);
+}
+#endif /* _DCCP_CCID2_H_ */
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
new file mode 100644
index 0000000..3b8bd7c
--- /dev/null
+++ b/net/dccp/ccids/ccid3.c
@@ -0,0 +1,986 @@
+/*
+ *  net/dccp/ccids/ccid3.c
+ *
+ *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
+ *  Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
+ *  Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz>
+ *
+ *  An implementation of the DCCP protocol
+ *
+ *  This code has been developed by the University of Waikato WAND
+ *  research group. For further information please see http://www.wand.net.nz/
+ *
+ *  This code also uses code from Lulea University, rereleased as GPL by its
+ *  authors:
+ *  Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
+ *
+ *  Changes to meet Linux coding standards, to make it meet latest ccid3 draft
+ *  and to make it work as a loadable module in the DCCP stack written by
+ *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
+ *
+ *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include "../dccp.h"
+#include "ccid3.h"
+
+#include <asm/unaligned.h>
+
+#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
+static int ccid3_debug;
+#define ccid3_pr_debug(format, a...)	DCCP_PR_DEBUG(ccid3_debug, format, ##a)
+#else
+#define ccid3_pr_debug(format, a...)
+#endif
+
+/*
+ *	Transmitter Half-Connection Routines
+ */
+#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
+static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state)
+{
+	static char *ccid3_state_names[] = {
+	[TFRC_SSTATE_NO_SENT]  = "NO_SENT",
+	[TFRC_SSTATE_NO_FBACK] = "NO_FBACK",
+	[TFRC_SSTATE_FBACK]    = "FBACK",
+	[TFRC_SSTATE_TERM]     = "TERM",
+	};
+
+	return ccid3_state_names[state];
+}
+#endif
+
+static void ccid3_hc_tx_set_state(struct sock *sk,
+				  enum ccid3_hc_tx_states state)
+{
+	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
+	enum ccid3_hc_tx_states oldstate = hctx->ccid3hctx_state;
+
+	ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
+		       dccp_role(sk), sk, ccid3_tx_state_name(oldstate),
+		       ccid3_tx_state_name(state));
+	WARN_ON(state == oldstate);
+	hctx->ccid3hctx_state = state;
+}
+
+/*
+ * Compute the initial sending rate X_init in the manner of RFC 3390:
+ *
+ *	X_init  =  min(4 * s, max(2 * s, 4380 bytes)) / RTT
+ *
+ * Note that RFC 3390 uses MSS, RFC 4342 refers to RFC 3390, and rfc3448bis
+ * (rev-02) clarifies the use of RFC 3390 with regard to the above formula.
+ * For consistency with other parts of the code, X_init is scaled by 2^6.
+ */
+static inline u64 rfc3390_initial_rate(struct sock *sk)
+{
+	const struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
+	const __u32 w_init = clamp_t(__u32, 4380U,
+			2 * hctx->ccid3hctx_s, 4 * hctx->ccid3hctx_s);
+
+	return scaled_div(w_init << 6, hctx->ccid3hctx_rtt);
+}
+
+/*
+ * Recalculate t_ipi and delta (should be called whenever X changes)
+ */
+static void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hctx)
+{
+	/* Calculate new t_ipi = s / X_inst (X_inst is in 64 * bytes/second) */
+	hctx->ccid3hctx_t_ipi = scaled_div32(((u64)hctx->ccid3hctx_s) << 6,
+					     hctx->ccid3hctx_x);
+
+	/* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */
+	hctx->ccid3hctx_delta = min_t(u32, hctx->ccid3hctx_t_ipi / 2,
+					   TFRC_OPSYS_HALF_TIME_GRAN);
+
+	ccid3_pr_debug("t_ipi=%u, delta=%u, s=%u, X=%u\n",
+		       hctx->ccid3hctx_t_ipi, hctx->ccid3hctx_delta,
+		       hctx->ccid3hctx_s, (unsigned)(hctx->ccid3hctx_x >> 6));
+
+}
+
+static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hctx, ktime_t now)
+{
+	u32 delta = ktime_us_delta(now, hctx->ccid3hctx_t_last_win_count);
+
+	return delta / hctx->ccid3hctx_rtt;
+}
+
+/**
+ * ccid3_hc_tx_update_x  -  Update allowed sending rate X
+ * @stamp: most recent time if available - can be left NULL.
+ * This function tracks draft rfc3448bis, check there for latest details.
+ *
+ * Note: X and X_recv are both stored in units of 64 * bytes/second, to support
+ *       fine-grained resolution of sending rates. This requires scaling by 2^6
+ *       throughout the code. Only X_calc is unscaled (in bytes/second).
+ *
+ */
+static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp)
+{
+	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;
+	ktime_t now = stamp ? *stamp : ktime_get_real();
+
+	/*
+	 * Handle IDLE periods: do not reduce below RFC3390 initial sending rate
+	 * when idling [RFC 4342, 5.1]. Definition of idling is from rfc3448bis:
+	 * a sender is idle if it has not sent anything over a 2-RTT-period.
+	 * For consistency with X and X_recv, min_rate is also scaled by 2^6.
+	 */
+	if (ccid3_hc_tx_idle_rtt(hctx, now) >= 2) {
+		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,
+					min_rate);
+		hctx->ccid3hctx_x = max(hctx->ccid3hctx_x,
+					(((__u64)hctx->ccid3hctx_s) << 6) /
+								TFRC_T_MBI);
+
+	} else if (ktime_us_delta(now, hctx->ccid3hctx_t_ld)
+				- (s64)hctx->ccid3hctx_rtt >= 0) {
+
+		hctx->ccid3hctx_x = min(2 * hctx->ccid3hctx_x, min_rate);
+		hctx->ccid3hctx_x = max(hctx->ccid3hctx_x,
+			    scaled_div(((__u64)hctx->ccid3hctx_s) << 6,
+				       hctx->ccid3hctx_rtt));
+		hctx->ccid3hctx_t_ld = now;
+	}
+
+	if (hctx->ccid3hctx_x != old_x) {
+		ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, "
+			       "X_recv=%u\n", (unsigned)(old_x >> 6),
+			       (unsigned)(hctx->ccid3hctx_x >> 6),
+			       hctx->ccid3hctx_x_calc,
+			       (unsigned)(hctx->ccid3hctx_x_recv >> 6));
+
+		ccid3_update_send_interval(hctx);
+	}
+}
+
+/*
+ *	Track the mean packet size `s' (cf. RFC 4342, 5.3 and  RFC 3448, 4.1)
+ *	@len: DCCP packet payload size in bytes
+ */
+static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hctx, int len)
+{
+	const u16 old_s = hctx->ccid3hctx_s;
+
+	hctx->ccid3hctx_s = tfrc_ewma(hctx->ccid3hctx_s, len, 9);
+
+	if (hctx->ccid3hctx_s != old_s)
+		ccid3_update_send_interval(hctx);
+}
+
+/*
+ *	Update Window Counter using the algorithm from [RFC 4342, 8.1].
+ *	As elsewhere, RTT > 0 is assumed by using dccp_sample_rtt().
+ */
+static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hctx,
+						ktime_t now)
+{
+	u32 delta = ktime_us_delta(now, hctx->ccid3hctx_t_last_win_count),
+	    quarter_rtts = (4 * delta) / hctx->ccid3hctx_rtt;
+
+	if (quarter_rtts > 0) {
+		hctx->ccid3hctx_t_last_win_count = now;
+		hctx->ccid3hctx_last_win_count  += min(quarter_rtts, 5U);
+		hctx->ccid3hctx_last_win_count	&= 0xF;		/* mod 16 */
+	}
+}
+
+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);
+	unsigned long t_nfb = USEC_PER_SEC / 5;
+
+	bh_lock_sock(sk);
+	if (sock_owned_by_user(sk)) {
+		/* Try again later. */
+		/* XXX: set some sensible MIB */
+		goto restart_timer;
+	}
+
+	ccid3_pr_debug("%s(%p, state=%s) - entry \n", dccp_role(sk), sk,
+		       ccid3_tx_state_name(hctx->ccid3hctx_state));
+
+	if (hctx->ccid3hctx_state == TFRC_SSTATE_FBACK)
+		ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
+	else if (hctx->ccid3hctx_state != TFRC_SSTATE_NO_FBACK)
+		goto out;
+
+	/*
+	 * Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4
+	 */
+	if (hctx->ccid3hctx_t_rto == 0 ||	/* no feedback received yet */
+	    hctx->ccid3hctx_p == 0) {
+
+		/* halve send rate directly */
+		hctx->ccid3hctx_x = max(hctx->ccid3hctx_x / 2,
+					(((__u64)hctx->ccid3hctx_s) << 6) /
+								    TFRC_T_MBI);
+		ccid3_update_send_interval(hctx);
+	} else {
+		/*
+		 *  Modify the cached value of X_recv
+		 *
+		 *  If (X_calc > 2 * X_recv)
+		 *    X_recv = max(X_recv / 2, s / (2 * t_mbi));
+		 *  Else
+		 *    X_recv = X_calc / 4;
+		 *
+		 *  Note that X_recv is scaled by 2^6 while X_calc is not
+		 */
+		BUG_ON(hctx->ccid3hctx_p && !hctx->ccid3hctx_x_calc);
+
+		if (hctx->ccid3hctx_x_calc > (hctx->ccid3hctx_x_recv >> 5))
+			hctx->ccid3hctx_x_recv =
+				max(hctx->ccid3hctx_x_recv / 2,
+				    (((__u64)hctx->ccid3hctx_s) << 6) /
+							      (2 * TFRC_T_MBI));
+		else {
+			hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc;
+			hctx->ccid3hctx_x_recv <<= 4;
+		}
+		ccid3_hc_tx_update_x(sk, NULL);
+	}
+	ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n",
+			(unsigned long long)hctx->ccid3hctx_x);
+
+	/*
+	 * Set new timeout for the nofeedback timer.
+	 * See comments in packet_recv() regarding the value of t_RTO.
+	 */
+	if (unlikely(hctx->ccid3hctx_t_rto == 0))	/* no feedback yet */
+		t_nfb = TFRC_INITIAL_TIMEOUT;
+	else
+		t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi);
+
+restart_timer:
+	sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
+			   jiffies + usecs_to_jiffies(t_nfb));
+out:
+	bh_unlock_sock(sk);
+	sock_put(sk);
+}
+
+/*
+ * returns
+ *   > 0: delay (in msecs) that should pass before actually sending
+ *   = 0: can send immediately
+ *   < 0: error condition; do not send packet
+ */
+static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
+{
+	struct dccp_sock *dp = dccp_sk(sk);
+	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
+	ktime_t now = ktime_get_real();
+	s64 delay;
+
+	/*
+	 * This function is called only for Data and DataAck packets. Sending
+	 * zero-sized Data(Ack)s is theoretically possible, but for congestion
+	 * control this case is pathological - ignore it.
+	 */
+	if (unlikely(skb->len == 0))
+		return -EBADMSG;
+
+	switch (hctx->ccid3hctx_state) {
+	case TFRC_SSTATE_NO_SENT:
+		sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
+			       (jiffies +
+				usecs_to_jiffies(TFRC_INITIAL_TIMEOUT)));
+		hctx->ccid3hctx_last_win_count	 = 0;
+		hctx->ccid3hctx_t_last_win_count = now;
+
+		/* Set t_0 for initial packet */
+		hctx->ccid3hctx_t_nom = now;
+
+		hctx->ccid3hctx_s = skb->len;
+
+		/*
+		 * Use initial RTT sample when available: recommended by erratum
+		 * to RFC 4342. This implements the initialisation procedure of
+		 * draft rfc3448bis, section 4.2. Remember, X is scaled by 2^6.
+		 */
+		if (dp->dccps_syn_rtt) {
+			ccid3_pr_debug("SYN RTT = %uus\n", dp->dccps_syn_rtt);
+			hctx->ccid3hctx_rtt  = dp->dccps_syn_rtt;
+			hctx->ccid3hctx_x    = rfc3390_initial_rate(sk);
+			hctx->ccid3hctx_t_ld = now;
+		} else {
+			/*
+			 * Sender does not have RTT sample:
+			 * - set fallback RTT (RFC 4340, 3.4) since a RTT value
+			 *   is needed in several parts (e.g.  window counter);
+			 * - set sending rate X_pps = 1pps as per RFC 3448, 4.2.
+			 */
+			hctx->ccid3hctx_rtt = DCCP_FALLBACK_RTT;
+			hctx->ccid3hctx_x   = hctx->ccid3hctx_s;
+			hctx->ccid3hctx_x <<= 6;
+		}
+		ccid3_update_send_interval(hctx);
+
+		ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
+		break;
+	case TFRC_SSTATE_NO_FBACK:
+	case TFRC_SSTATE_FBACK:
+		delay = ktime_us_delta(hctx->ccid3hctx_t_nom, now);
+		ccid3_pr_debug("delay=%ld\n", (long)delay);
+		/*
+		 *	Scheduling of packet transmissions [RFC 3448, 4.6]
+		 *
+		 * if (t_now > t_nom - delta)
+		 *       // send the packet now
+		 * else
+		 *       // send the packet in (t_nom - t_now) milliseconds.
+		 */
+		if (delay - (s64)hctx->ccid3hctx_delta >= 1000)
+			return (u32)delay / 1000L;
+
+		ccid3_hc_tx_update_win_count(hctx, now);
+		break;
+	case TFRC_SSTATE_TERM:
+		DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk);
+		return -EINVAL;
+	}
+
+	/* 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;
+
+	/* set the nominal send time for the next following packet */
+	hctx->ccid3hctx_t_nom = ktime_add_us(hctx->ccid3hctx_t_nom,
+					     hctx->ccid3hctx_t_ipi);
+	return 0;
+}
+
+static void ccid3_hc_tx_packet_sent(struct sock *sk, int more,
+				    unsigned int len)
+{
+	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
+
+	ccid3_hc_tx_update_s(hctx, len);
+
+	if (tfrc_tx_hist_add(&hctx->ccid3hctx_hist, dccp_sk(sk)->dccps_gss))
+		DCCP_CRIT("packet history - out of memory!");
+}
+
+static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
+{
+	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
+	struct ccid3_options_received *opt_recv;
+	ktime_t now;
+	unsigned long t_nfb;
+	u32 pinv, r_sample;
+
+	/* we are only interested in ACKs */
+	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;
+	now = ktime_get_real();
+
+	/* 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) {
+		DCCP_WARN("%s(%p): %s with bogus ACK-%llu\n", dccp_role(sk), sk,
+			  dccp_packet_name(DCCP_SKB_CB(skb)->dccpd_type),
+			  (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq);
+		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 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;
+	else				       /* can not exceed 100% */
+		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) {
+			/*
+			 * 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);
+
+			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)
+		hctx->ccid3hctx_x_calc =
+				tfrc_calc_x(hctx->ccid3hctx_s,
+					    hctx->ccid3hctx_rtt,
+					    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),
+			       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);
+
+	/*
+	 * 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);
+
+	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));
+}
+
+static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option,
+				     unsigned char len, u16 idx,
+				     unsigned char *value)
+{
+	int rc = 0;
+	const struct dccp_sock *dp = dccp_sk(sk);
+	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
+	struct ccid3_options_received *opt_recv;
+	__be32 opt_val;
+
+	opt_recv = &hctx->ccid3hctx_options_received;
+
+	if (opt_recv->ccid3or_seqno != dp->dccps_gsr) {
+		opt_recv->ccid3or_seqno		     = dp->dccps_gsr;
+		opt_recv->ccid3or_loss_event_rate    = ~0;
+		opt_recv->ccid3or_loss_intervals_idx = 0;
+		opt_recv->ccid3or_loss_intervals_len = 0;
+		opt_recv->ccid3or_receive_rate	     = 0;
+	}
+
+	switch (option) {
+	case TFRC_OPT_LOSS_EVENT_RATE:
+		if (unlikely(len != 4)) {
+			DCCP_WARN("%s(%p), invalid len %d "
+				  "for TFRC_OPT_LOSS_EVENT_RATE\n",
+				  dccp_role(sk), sk, len);
+			rc = -EINVAL;
+		} else {
+			opt_val = get_unaligned((__be32 *)value);
+			opt_recv->ccid3or_loss_event_rate = ntohl(opt_val);
+			ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n",
+				       dccp_role(sk), sk,
+				       opt_recv->ccid3or_loss_event_rate);
+		}
+		break;
+	case TFRC_OPT_LOSS_INTERVALS:
+		opt_recv->ccid3or_loss_intervals_idx = idx;
+		opt_recv->ccid3or_loss_intervals_len = len;
+		ccid3_pr_debug("%s(%p), LOSS_INTERVALS=(%u, %u)\n",
+			       dccp_role(sk), sk,
+			       opt_recv->ccid3or_loss_intervals_idx,
+			       opt_recv->ccid3or_loss_intervals_len);
+		break;
+	case TFRC_OPT_RECEIVE_RATE:
+		if (unlikely(len != 4)) {
+			DCCP_WARN("%s(%p), invalid len %d "
+				  "for TFRC_OPT_RECEIVE_RATE\n",
+				  dccp_role(sk), sk, len);
+			rc = -EINVAL;
+		} else {
+			opt_val = get_unaligned((__be32 *)value);
+			opt_recv->ccid3or_receive_rate = ntohl(opt_val);
+			ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n",
+				       dccp_role(sk), sk,
+				       opt_recv->ccid3or_receive_rate);
+		}
+		break;
+	}
+
+	return rc;
+}
+
+static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk)
+{
+	struct ccid3_hc_tx_sock *hctx = ccid_priv(ccid);
+
+	hctx->ccid3hctx_state = TFRC_SSTATE_NO_SENT;
+	hctx->ccid3hctx_hist = NULL;
+	setup_timer(&hctx->ccid3hctx_no_feedback_timer,
+			ccid3_hc_tx_no_feedback_timer, (unsigned long)sk);
+
+	return 0;
+}
+
+static void ccid3_hc_tx_exit(struct sock *sk)
+{
+	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
+
+	ccid3_hc_tx_set_state(sk, TFRC_SSTATE_TERM);
+	sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);
+
+	tfrc_tx_hist_purge(&hctx->ccid3hctx_hist);
+}
+
+static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info)
+{
+	struct ccid3_hc_tx_sock *hctx;
+
+	/* Listen socks doesn't have a private CCID block */
+	if (sk->sk_state == DCCP_LISTEN)
+		return;
+
+	hctx = ccid3_hc_tx_sk(sk);
+	info->tcpi_rto = hctx->ccid3hctx_t_rto;
+	info->tcpi_rtt = hctx->ccid3hctx_rtt;
+}
+
+static int ccid3_hc_tx_getsockopt(struct sock *sk, const int optname, int len,
+				  u32 __user *optval, int __user *optlen)
+{
+	const struct ccid3_hc_tx_sock *hctx;
+	const void *val;
+
+	/* Listen socks doesn't have a private CCID block */
+	if (sk->sk_state == DCCP_LISTEN)
+		return -EINVAL;
+
+	hctx = ccid3_hc_tx_sk(sk);
+	switch (optname) {
+	case DCCP_SOCKOPT_CCID_TX_INFO:
+		if (len < sizeof(hctx->ccid3hctx_tfrc))
+			return -EINVAL;
+		len = sizeof(hctx->ccid3hctx_tfrc);
+		val = &hctx->ccid3hctx_tfrc;
+		break;
+	default:
+		return -ENOPROTOOPT;
+	}
+
+	if (put_user(len, optlen) || copy_to_user(optval, val, len))
+		return -EFAULT;
+
+	return 0;
+}
+
+/*
+ *	Receiver Half-Connection Routines
+ */
+
+/* CCID3 feedback types */
+enum ccid3_fback_type {
+	CCID3_FBACK_NONE = 0,
+	CCID3_FBACK_INITIAL,
+	CCID3_FBACK_PERIODIC,
+	CCID3_FBACK_PARAM_CHANGE
+};
+
+#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
+static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state)
+{
+	static char *ccid3_rx_state_names[] = {
+	[TFRC_RSTATE_NO_DATA] = "NO_DATA",
+	[TFRC_RSTATE_DATA]    = "DATA",
+	[TFRC_RSTATE_TERM]    = "TERM",
+	};
+
+	return ccid3_rx_state_names[state];
+}
+#endif
+
+static void ccid3_hc_rx_set_state(struct sock *sk,
+				  enum ccid3_hc_rx_states state)
+{
+	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
+	enum ccid3_hc_rx_states oldstate = hcrx->ccid3hcrx_state;
+
+	ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
+		       dccp_role(sk), sk, ccid3_rx_state_name(oldstate),
+		       ccid3_rx_state_name(state));
+	WARN_ON(state == oldstate);
+	hcrx->ccid3hcrx_state = state;
+}
+
+static void ccid3_hc_rx_send_feedback(struct sock *sk,
+				      const struct sk_buff *skb,
+				      enum ccid3_fback_type fbtype)
+{
+	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
+	struct dccp_sock *dp = dccp_sk(sk);
+	ktime_t now;
+	s64 delta = 0;
+
+	if (unlikely(hcrx->ccid3hcrx_state == TFRC_RSTATE_TERM))
+		return;
+
+	now = ktime_get_real();
+
+	switch (fbtype) {
+	case CCID3_FBACK_INITIAL:
+		hcrx->ccid3hcrx_x_recv = 0;
+		hcrx->ccid3hcrx_pinv   = ~0U;   /* see RFC 4342, 8.5 */
+		break;
+	case CCID3_FBACK_PARAM_CHANGE:
+		/*
+		 * When parameters change (new loss or p > p_prev), we do not
+		 * have a reliable estimate for R_m of [RFC 3448, 6.2] and so
+		 * need to  reuse the previous value of X_recv. However, when
+		 * X_recv was 0 (due to early loss), this would kill X down to
+		 * s/t_mbi (i.e. one packet in 64 seconds).
+		 * To avoid such drastic reduction, we approximate X_recv as
+		 * the number of bytes since last feedback.
+		 * This is a safe fallback, since X is bounded above by X_calc.
+		 */
+		if (hcrx->ccid3hcrx_x_recv > 0)
+			break;
+		/* fall through */
+	case CCID3_FBACK_PERIODIC:
+		delta = ktime_us_delta(now, hcrx->ccid3hcrx_tstamp_last_feedback);
+		if (delta <= 0)
+			DCCP_BUG("delta (%ld) <= 0", (long)delta);
+		else
+			hcrx->ccid3hcrx_x_recv =
+				scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);
+		break;
+	default:
+		return;
+	}
+
+	ccid3_pr_debug("Interval %ldusec, X_recv=%u, 1/p=%u\n", (long)delta,
+		       hcrx->ccid3hcrx_x_recv, hcrx->ccid3hcrx_pinv);
+
+	hcrx->ccid3hcrx_tstamp_last_feedback = now;
+	hcrx->ccid3hcrx_last_counter	     = dccp_hdr(skb)->dccph_ccval;
+	hcrx->ccid3hcrx_bytes_recv	     = 0;
+
+	dp->dccps_hc_rx_insert_options = 1;
+	dccp_send_ack(sk);
+}
+
+static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
+{
+	const struct ccid3_hc_rx_sock *hcrx;
+	__be32 x_recv, pinv;
+
+	if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN))
+		return 0;
+
+	hcrx = ccid3_hc_rx_sk(sk);
+
+	if (dccp_packet_without_ack(skb))
+		return 0;
+
+	x_recv = htonl(hcrx->ccid3hcrx_x_recv);
+	pinv   = htonl(hcrx->ccid3hcrx_pinv);
+
+	if (dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE,
+			       &pinv, sizeof(pinv)) ||
+	    dccp_insert_option(sk, skb, TFRC_OPT_RECEIVE_RATE,
+			       &x_recv, sizeof(x_recv)))
+		return -1;
+
+	return 0;
+}
+
+/** ccid3_first_li  -  Implements [RFC 3448, 6.3.1]
+ *
+ * Determine the length of the first loss interval via inverse lookup.
+ * Assume that X_recv can be computed by the throughput equation
+ *		    s
+ *	X_recv = --------
+ *		 R * fval
+ * Find some p such that f(p) = fval; return 1/p (scaled).
+ */
+static u32 ccid3_first_li(struct sock *sk)
+{
+	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
+	u32 x_recv, p, delta;
+	u64 fval;
+
+	if (hcrx->ccid3hcrx_rtt == 0) {
+		DCCP_WARN("No RTT estimate available, using fallback RTT\n");
+		hcrx->ccid3hcrx_rtt = DCCP_FALLBACK_RTT;
+	}
+
+	delta = ktime_to_us(net_timedelta(hcrx->ccid3hcrx_tstamp_last_feedback));
+	x_recv = scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);
+	if (x_recv == 0) {		/* would also trigger divide-by-zero */
+		DCCP_WARN("X_recv==0\n");
+		if ((x_recv = hcrx->ccid3hcrx_x_recv) == 0) {
+			DCCP_BUG("stored value of X_recv is zero");
+			return ~0U;
+		}
+	}
+
+	fval = scaled_div(hcrx->ccid3hcrx_s, hcrx->ccid3hcrx_rtt);
+	fval = scaled_div32(fval, x_recv);
+	p = tfrc_calc_x_reverse_lookup(fval);
+
+	ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
+		       "loss rate=%u\n", dccp_role(sk), sk, x_recv, p);
+
+	return p == 0 ? ~0U : scaled_div(1, p);
+}
+
+static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
+{
+	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
+	enum ccid3_fback_type do_feedback = CCID3_FBACK_NONE;
+	const u64 ndp = dccp_sk(sk)->dccps_options_received.dccpor_ndp;
+	const bool is_data_packet = dccp_data_packet(skb);
+
+	if (unlikely(hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)) {
+		if (is_data_packet) {
+			const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4;
+			do_feedback = CCID3_FBACK_INITIAL;
+			ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA);
+			hcrx->ccid3hcrx_s = payload;
+			/*
+			 * Not necessary to update ccid3hcrx_bytes_recv here,
+			 * since X_recv = 0 for the first feedback packet (cf.
+			 * RFC 3448, 6.3) -- gerrit
+			 */
+		}
+		goto update_records;
+	}
+
+	if (tfrc_rx_hist_duplicate(&hcrx->ccid3hcrx_hist, skb))
+		return; /* done receiving */
+
+	if (is_data_packet) {
+		const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4;
+		/*
+		 * Update moving-average of s and the sum of received payload bytes
+		 */
+		hcrx->ccid3hcrx_s = tfrc_ewma(hcrx->ccid3hcrx_s, payload, 9);
+		hcrx->ccid3hcrx_bytes_recv += payload;
+	}
+
+	/*
+	 * Perform loss detection and handle pending losses
+	 */
+	if (tfrc_rx_handle_loss(&hcrx->ccid3hcrx_hist, &hcrx->ccid3hcrx_li_hist,
+				skb, ndp, ccid3_first_li, sk)) {
+		do_feedback = CCID3_FBACK_PARAM_CHANGE;
+		goto done_receiving;
+	}
+
+	if (tfrc_rx_hist_loss_pending(&hcrx->ccid3hcrx_hist))
+		return; /* done receiving */
+
+	/*
+	 * Handle data packets: RTT sampling and monitoring p
+	 */
+	if (unlikely(!is_data_packet))
+		goto update_records;
+
+	if (!tfrc_lh_is_initialised(&hcrx->ccid3hcrx_li_hist)) {
+		const u32 sample = tfrc_rx_hist_sample_rtt(&hcrx->ccid3hcrx_hist, skb);
+		/*
+		 * Empty loss history: no loss so far, hence p stays 0.
+		 * Sample RTT values, since an RTT estimate is required for the
+		 * computation of p when the first loss occurs; RFC 3448, 6.3.1.
+		 */
+		if (sample != 0)
+			hcrx->ccid3hcrx_rtt = tfrc_ewma(hcrx->ccid3hcrx_rtt, sample, 9);
+
+	} else if (tfrc_lh_update_i_mean(&hcrx->ccid3hcrx_li_hist, skb)) {
+		/*
+		 * Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean
+		 * has decreased (resp. p has increased), send feedback now.
+		 */
+		do_feedback = CCID3_FBACK_PARAM_CHANGE;
+	}
+
+	/*
+	 * Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3
+	 */
+	if (SUB16(dccp_hdr(skb)->dccph_ccval, hcrx->ccid3hcrx_last_counter) > 3)
+		do_feedback = CCID3_FBACK_PERIODIC;
+
+update_records:
+	tfrc_rx_hist_add_packet(&hcrx->ccid3hcrx_hist, skb, ndp);
+
+done_receiving:
+	if (do_feedback)
+		ccid3_hc_rx_send_feedback(sk, skb, do_feedback);
+}
+
+static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
+{
+	struct ccid3_hc_rx_sock *hcrx = ccid_priv(ccid);
+
+	hcrx->ccid3hcrx_state = TFRC_RSTATE_NO_DATA;
+	tfrc_lh_init(&hcrx->ccid3hcrx_li_hist);
+	return tfrc_rx_hist_alloc(&hcrx->ccid3hcrx_hist);
+}
+
+static void ccid3_hc_rx_exit(struct sock *sk)
+{
+	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
+
+	ccid3_hc_rx_set_state(sk, TFRC_RSTATE_TERM);
+
+	tfrc_rx_hist_purge(&hcrx->ccid3hcrx_hist);
+	tfrc_lh_cleanup(&hcrx->ccid3hcrx_li_hist);
+}
+
+static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)
+{
+	const struct ccid3_hc_rx_sock *hcrx;
+
+	/* Listen socks doesn't have a private CCID block */
+	if (sk->sk_state == DCCP_LISTEN)
+		return;
+
+	hcrx = ccid3_hc_rx_sk(sk);
+	info->tcpi_ca_state = hcrx->ccid3hcrx_state;
+	info->tcpi_options  |= TCPI_OPT_TIMESTAMPS;
+	info->tcpi_rcv_rtt  = hcrx->ccid3hcrx_rtt;
+}
+
+static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len,
+				  u32 __user *optval, int __user *optlen)
+{
+	const struct ccid3_hc_rx_sock *hcrx;
+	struct tfrc_rx_info rx_info;
+	const void *val;
+
+	/* Listen socks doesn't have a private CCID block */
+	if (sk->sk_state == DCCP_LISTEN)
+		return -EINVAL;
+
+	hcrx = ccid3_hc_rx_sk(sk);
+	switch (optname) {
+	case DCCP_SOCKOPT_CCID_RX_INFO:
+		if (len < sizeof(rx_info))
+			return -EINVAL;
+		rx_info.tfrcrx_x_recv = hcrx->ccid3hcrx_x_recv;
+		rx_info.tfrcrx_rtt    = hcrx->ccid3hcrx_rtt;
+		rx_info.tfrcrx_p      = hcrx->ccid3hcrx_pinv == 0 ? ~0U :
+					   scaled_div(1, hcrx->ccid3hcrx_pinv);
+		len = sizeof(rx_info);
+		val = &rx_info;
+		break;
+	default:
+		return -ENOPROTOOPT;
+	}
+
+	if (put_user(len, optlen) || copy_to_user(optval, val, len))
+		return -EFAULT;
+
+	return 0;
+}
+
+static struct ccid_operations ccid3 = {
+	.ccid_id		   = DCCPC_CCID3,
+	.ccid_name		   = "TCP-Friendly Rate Control",
+	.ccid_owner		   = THIS_MODULE,
+	.ccid_hc_tx_obj_size	   = sizeof(struct ccid3_hc_tx_sock),
+	.ccid_hc_tx_init	   = ccid3_hc_tx_init,
+	.ccid_hc_tx_exit	   = ccid3_hc_tx_exit,
+	.ccid_hc_tx_send_packet	   = ccid3_hc_tx_send_packet,
+	.ccid_hc_tx_packet_sent	   = ccid3_hc_tx_packet_sent,
+	.ccid_hc_tx_packet_recv	   = ccid3_hc_tx_packet_recv,
+	.ccid_hc_tx_parse_options  = ccid3_hc_tx_parse_options,
+	.ccid_hc_rx_obj_size	   = sizeof(struct ccid3_hc_rx_sock),
+	.ccid_hc_rx_init	   = ccid3_hc_rx_init,
+	.ccid_hc_rx_exit	   = ccid3_hc_rx_exit,
+	.ccid_hc_rx_insert_options = ccid3_hc_rx_insert_options,
+	.ccid_hc_rx_packet_recv	   = ccid3_hc_rx_packet_recv,
+	.ccid_hc_rx_get_info	   = ccid3_hc_rx_get_info,
+	.ccid_hc_tx_get_info	   = ccid3_hc_tx_get_info,
+	.ccid_hc_rx_getsockopt	   = ccid3_hc_rx_getsockopt,
+	.ccid_hc_tx_getsockopt	   = ccid3_hc_tx_getsockopt,
+};
+
+#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
+module_param(ccid3_debug, bool, 0644);
+MODULE_PARM_DESC(ccid3_debug, "Enable debug messages");
+#endif
+
+static __init int ccid3_module_init(void)
+{
+	return ccid_register(&ccid3);
+}
+module_init(ccid3_module_init);
+
+static __exit void ccid3_module_exit(void)
+{
+	ccid_unregister(&ccid3);
+}
+module_exit(ccid3_module_exit);
+
+MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>, "
+	      "Arnaldo Carvalho de Melo <acme@ghostprotocols.net>");
+MODULE_DESCRIPTION("DCCP TFRC CCID3 CCID");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("net-dccp-ccid-3");
diff --git a/net/dccp/ccids/ccid3.h b/net/dccp/ccids/ccid3.h
new file mode 100644
index 0000000..49ca32b
--- /dev/null
+++ b/net/dccp/ccids/ccid3.h
@@ -0,0 +1,171 @@
+/*
+ *  net/dccp/ccids/ccid3.h
+ *
+ *  Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
+ *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
+ *
+ *  An implementation of the DCCP protocol
+ *
+ *  This code has been developed by the University of Waikato WAND
+ *  research group. For further information please see http://www.wand.net.nz/
+ *  or e-mail Ian McDonald - ian.mcdonald@jandi.co.nz
+ *
+ *  This code also uses code from Lulea University, rereleased as GPL by its
+ *  authors:
+ *  Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
+ *
+ *  Changes to meet Linux coding standards, to make it meet latest ccid3 draft
+ *  and to make it work as a loadable module in the DCCP stack written by
+ *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
+ *
+ *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#ifndef _DCCP_CCID3_H_
+#define _DCCP_CCID3_H_
+
+#include <linux/ktime.h>
+#include <linux/list.h>
+#include <linux/types.h>
+#include <linux/tfrc.h>
+#include "lib/tfrc.h"
+#include "../ccid.h"
+
+/* Two seconds as per RFC 3448 4.2 */
+#define TFRC_INITIAL_TIMEOUT	   (2 * USEC_PER_SEC)
+
+/* In usecs - half the scheduling granularity as per RFC3448 4.6 */
+#define TFRC_OPSYS_HALF_TIME_GRAN  (USEC_PER_SEC / (2 * HZ))
+
+/* Parameter t_mbi from [RFC 3448, 4.3]: backoff interval in seconds */
+#define TFRC_T_MBI		   64
+
+enum ccid3_options {
+	TFRC_OPT_LOSS_EVENT_RATE = 192,
+	TFRC_OPT_LOSS_INTERVALS	 = 193,
+	TFRC_OPT_RECEIVE_RATE	 = 194,
+};
+
+struct ccid3_options_received {
+	u64 ccid3or_seqno:48,
+	    ccid3or_loss_intervals_idx:16;
+	u16 ccid3or_loss_intervals_len;
+	u32 ccid3or_loss_event_rate;
+	u32 ccid3or_receive_rate;
+};
+
+/* TFRC sender states */
+enum ccid3_hc_tx_states {
+	TFRC_SSTATE_NO_SENT = 1,
+	TFRC_SSTATE_NO_FBACK,
+	TFRC_SSTATE_FBACK,
+	TFRC_SSTATE_TERM,
+};
+
+/** struct ccid3_hc_tx_sock - CCID3 sender half-connection socket
+ *
+ * @ccid3hctx_x - Current sending rate in 64 * bytes per second
+ * @ccid3hctx_x_recv - Receive rate    in 64 * bytes per second
+ * @ccid3hctx_x_calc - Calculated rate in bytes per second
+ * @ccid3hctx_rtt - Estimate of current round trip time in usecs
+ * @ccid3hctx_p - Current loss event rate (0-1) scaled by 1000000
+ * @ccid3hctx_s - Packet size in bytes
+ * @ccid3hctx_t_rto - Nofeedback Timer setting in usecs
+ * @ccid3hctx_t_ipi - Interpacket (send) interval (RFC 3448, 4.6) in usecs
+ * @ccid3hctx_state - Sender state, one of %ccid3_hc_tx_states
+ * @ccid3hctx_last_win_count - Last window counter sent
+ * @ccid3hctx_t_last_win_count - Timestamp of earliest packet
+ *				 with last_win_count value sent
+ * @ccid3hctx_no_feedback_timer - Handle to no feedback timer
+ * @ccid3hctx_t_ld - Time last doubled during slow start
+ * @ccid3hctx_t_nom - Nominal send time of next packet
+ * @ccid3hctx_delta - Send timer delta (RFC 3448, 4.6) in usecs
+ * @ccid3hctx_hist - Packet history
+ * @ccid3hctx_options_received - Parsed set of retrieved options
+ */
+struct ccid3_hc_tx_sock {
+	struct tfrc_tx_info		ccid3hctx_tfrc;
+#define ccid3hctx_x			ccid3hctx_tfrc.tfrctx_x
+#define ccid3hctx_x_recv		ccid3hctx_tfrc.tfrctx_x_recv
+#define ccid3hctx_x_calc		ccid3hctx_tfrc.tfrctx_x_calc
+#define ccid3hctx_rtt			ccid3hctx_tfrc.tfrctx_rtt
+#define ccid3hctx_p			ccid3hctx_tfrc.tfrctx_p
+#define ccid3hctx_t_rto			ccid3hctx_tfrc.tfrctx_rto
+#define ccid3hctx_t_ipi			ccid3hctx_tfrc.tfrctx_ipi
+	u16				ccid3hctx_s;
+	enum ccid3_hc_tx_states		ccid3hctx_state:8;
+	u8				ccid3hctx_last_win_count;
+	ktime_t				ccid3hctx_t_last_win_count;
+	struct timer_list		ccid3hctx_no_feedback_timer;
+	ktime_t				ccid3hctx_t_ld;
+	ktime_t				ccid3hctx_t_nom;
+	u32				ccid3hctx_delta;
+	struct tfrc_tx_hist_entry	*ccid3hctx_hist;
+	struct ccid3_options_received	ccid3hctx_options_received;
+};
+
+static inline struct ccid3_hc_tx_sock *ccid3_hc_tx_sk(const struct sock *sk)
+{
+    struct ccid3_hc_tx_sock *hctx = ccid_priv(dccp_sk(sk)->dccps_hc_tx_ccid);
+    BUG_ON(hctx == NULL);
+    return hctx;
+}
+
+/* TFRC receiver states */
+enum ccid3_hc_rx_states {
+	TFRC_RSTATE_NO_DATA = 1,
+	TFRC_RSTATE_DATA,
+	TFRC_RSTATE_TERM    = 127,
+};
+
+/** struct ccid3_hc_rx_sock - CCID3 receiver half-connection socket
+ *
+ *  @ccid3hcrx_x_recv  -  Receiver estimate of send rate (RFC 3448 4.3)
+ *  @ccid3hcrx_rtt  -  Receiver estimate of rtt (non-standard)
+ *  @ccid3hcrx_p  -  Current loss event rate (RFC 3448 5.4)
+ *  @ccid3hcrx_last_counter  -  Tracks window counter (RFC 4342, 8.1)
+ *  @ccid3hcrx_state  -  Receiver state, one of %ccid3_hc_rx_states
+ *  @ccid3hcrx_bytes_recv  -  Total sum of DCCP payload bytes
+ *  @ccid3hcrx_x_recv  -  Receiver estimate of send rate (RFC 3448, sec. 4.3)
+ *  @ccid3hcrx_rtt  -  Receiver estimate of RTT
+ *  @ccid3hcrx_tstamp_last_feedback  -  Time at which last feedback was sent
+ *  @ccid3hcrx_tstamp_last_ack  -  Time at which last feedback was sent
+ *  @ccid3hcrx_hist  -  Packet history (loss detection + RTT sampling)
+ *  @ccid3hcrx_li_hist  -  Loss Interval database
+ *  @ccid3hcrx_s  -  Received packet size in bytes
+ *  @ccid3hcrx_pinv  -  Inverse of Loss Event Rate (RFC 4342, sec. 8.5)
+ */
+struct ccid3_hc_rx_sock {
+	u8				ccid3hcrx_last_counter:4;
+	enum ccid3_hc_rx_states		ccid3hcrx_state:8;
+	u32				ccid3hcrx_bytes_recv;
+	u32				ccid3hcrx_x_recv;
+	u32				ccid3hcrx_rtt;
+	ktime_t				ccid3hcrx_tstamp_last_feedback;
+	struct tfrc_rx_hist		ccid3hcrx_hist;
+	struct tfrc_loss_hist		ccid3hcrx_li_hist;
+	u16				ccid3hcrx_s;
+#define ccid3hcrx_pinv			ccid3hcrx_li_hist.i_mean
+};
+
+static inline struct ccid3_hc_rx_sock *ccid3_hc_rx_sk(const struct sock *sk)
+{
+    struct ccid3_hc_rx_sock *hcrx = ccid_priv(dccp_sk(sk)->dccps_hc_rx_ccid);
+    BUG_ON(hcrx == NULL);
+    return hcrx;
+}
+
+#endif /* _DCCP_CCID3_H_ */
diff --git a/net/dccp/ccids/lib/Makefile b/net/dccp/ccids/lib/Makefile
new file mode 100644
index 0000000..68c93e3
--- /dev/null
+++ b/net/dccp/ccids/lib/Makefile
@@ -0,0 +1,3 @@
+obj-$(CONFIG_IP_DCCP_TFRC_LIB) += dccp_tfrc_lib.o
+
+dccp_tfrc_lib-y := tfrc.o tfrc_equation.o packet_history.o loss_interval.o
diff --git a/net/dccp/ccids/lib/loss_interval.c b/net/dccp/ccids/lib/loss_interval.c
new file mode 100644
index 0000000..5b3ce06
--- /dev/null
+++ b/net/dccp/ccids/lib/loss_interval.c
@@ -0,0 +1,188 @@
+/*
+ *  net/dccp/ccids/lib/loss_interval.c
+ *
+ *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
+ *  Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
+ *  Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz>
+ *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ */
+#include <net/sock.h>
+#include "tfrc.h"
+
+static struct kmem_cache  *tfrc_lh_slab  __read_mostly;
+/* Loss Interval weights from [RFC 3448, 5.4], scaled by 10 */
+static const int tfrc_lh_weights[NINTERVAL] = { 10, 10, 10, 10, 8, 6, 4, 2 };
+
+/* implements LIFO semantics on the array */
+static inline u8 LIH_INDEX(const u8 ctr)
+{
+	return (LIH_SIZE - 1 - (ctr % LIH_SIZE));
+}
+
+/* the `counter' index always points at the next entry to be populated */
+static inline struct tfrc_loss_interval *tfrc_lh_peek(struct tfrc_loss_hist *lh)
+{
+	return lh->counter ? lh->ring[LIH_INDEX(lh->counter - 1)] : NULL;
+}
+
+/* given i with 0 <= i <= k, return I_i as per the rfc3448bis notation */
+static inline u32 tfrc_lh_get_interval(struct tfrc_loss_hist *lh, const u8 i)
+{
+	BUG_ON(i >= lh->counter);
+	return lh->ring[LIH_INDEX(lh->counter - i - 1)]->li_length;
+}
+
+/*
+ *	On-demand allocation and de-allocation of entries
+ */
+static struct tfrc_loss_interval *tfrc_lh_demand_next(struct tfrc_loss_hist *lh)
+{
+	if (lh->ring[LIH_INDEX(lh->counter)] == NULL)
+		lh->ring[LIH_INDEX(lh->counter)] = kmem_cache_alloc(tfrc_lh_slab,
+								    GFP_ATOMIC);
+	return lh->ring[LIH_INDEX(lh->counter)];
+}
+
+void tfrc_lh_cleanup(struct tfrc_loss_hist *lh)
+{
+	if (!tfrc_lh_is_initialised(lh))
+		return;
+
+	for (lh->counter = 0; lh->counter < LIH_SIZE; lh->counter++)
+		if (lh->ring[LIH_INDEX(lh->counter)] != NULL) {
+			kmem_cache_free(tfrc_lh_slab,
+					lh->ring[LIH_INDEX(lh->counter)]);
+			lh->ring[LIH_INDEX(lh->counter)] = NULL;
+		}
+}
+EXPORT_SYMBOL_GPL(tfrc_lh_cleanup);
+
+static void tfrc_lh_calc_i_mean(struct tfrc_loss_hist *lh)
+{
+	u32 i_i, i_tot0 = 0, i_tot1 = 0, w_tot = 0;
+	int i, k = tfrc_lh_length(lh) - 1; /* k is as in rfc3448bis, 5.4 */
+
+	if (k <= 0)
+		return;
+
+	for (i = 0; i <= k; i++) {
+		i_i = tfrc_lh_get_interval(lh, i);
+
+		if (i < k) {
+			i_tot0 += i_i * tfrc_lh_weights[i];
+			w_tot  += tfrc_lh_weights[i];
+		}
+		if (i > 0)
+			i_tot1 += i_i * tfrc_lh_weights[i-1];
+	}
+
+	lh->i_mean = max(i_tot0, i_tot1) / w_tot;
+}
+
+/**
+ * tfrc_lh_update_i_mean  -  Update the `open' loss interval I_0
+ * For recomputing p: returns `true' if p > p_prev  <=>  1/p < 1/p_prev
+ */
+u8 tfrc_lh_update_i_mean(struct tfrc_loss_hist *lh, struct sk_buff *skb)
+{
+	struct tfrc_loss_interval *cur = tfrc_lh_peek(lh);
+	u32 old_i_mean = lh->i_mean;
+	s64 len;
+
+	if (cur == NULL)			/* not initialised */
+		return 0;
+
+	len = dccp_delta_seqno(cur->li_seqno, DCCP_SKB_CB(skb)->dccpd_seq) + 1;
+
+	if (len - (s64)cur->li_length <= 0)	/* duplicate or reordered */
+		return 0;
+
+	if (SUB16(dccp_hdr(skb)->dccph_ccval, cur->li_ccval) > 4)
+		/*
+		 * Implements RFC 4342, 10.2:
+		 * If a packet S (skb) exists whose seqno comes `after' the one
+		 * starting the current loss interval (cur) and if the modulo-16
+		 * distance from C(cur) to C(S) is greater than 4, consider all
+		 * subsequent packets as belonging to a new loss interval. This
+		 * test is necessary since CCVal may wrap between intervals.
+		 */
+		cur->li_is_closed = 1;
+
+	if (tfrc_lh_length(lh) == 1)		/* due to RFC 3448, 6.3.1 */
+		return 0;
+
+	cur->li_length = len;
+	tfrc_lh_calc_i_mean(lh);
+
+	return (lh->i_mean < old_i_mean);
+}
+EXPORT_SYMBOL_GPL(tfrc_lh_update_i_mean);
+
+/* Determine if `new_loss' does begin a new loss interval [RFC 4342, 10.2] */
+static inline u8 tfrc_lh_is_new_loss(struct tfrc_loss_interval *cur,
+				     struct tfrc_rx_hist_entry *new_loss)
+{
+	return	dccp_delta_seqno(cur->li_seqno, new_loss->tfrchrx_seqno) > 0 &&
+		(cur->li_is_closed || SUB16(new_loss->tfrchrx_ccval, cur->li_ccval) > 4);
+}
+
+/** tfrc_lh_interval_add  -  Insert new record into the Loss Interval database
+ * @lh:		   Loss Interval database
+ * @rh:		   Receive history containing a fresh loss event
+ * @calc_first_li: Caller-dependent routine to compute length of first interval
+ * @sk:		   Used by @calc_first_li in caller-specific way (subtyping)
+ * Updates I_mean and returns 1 if a new interval has in fact been added to @lh.
+ */
+int tfrc_lh_interval_add(struct tfrc_loss_hist *lh, struct tfrc_rx_hist *rh,
+			 u32 (*calc_first_li)(struct sock *), struct sock *sk)
+{
+	struct tfrc_loss_interval *cur = tfrc_lh_peek(lh), *new;
+
+	if (cur != NULL && !tfrc_lh_is_new_loss(cur, tfrc_rx_hist_loss_prev(rh)))
+		return 0;
+
+	new = tfrc_lh_demand_next(lh);
+	if (unlikely(new == NULL)) {
+		DCCP_CRIT("Cannot allocate/add loss record.");
+		return 0;
+	}
+
+	new->li_seqno	  = tfrc_rx_hist_loss_prev(rh)->tfrchrx_seqno;
+	new->li_ccval	  = tfrc_rx_hist_loss_prev(rh)->tfrchrx_ccval;
+	new->li_is_closed = 0;
+
+	if (++lh->counter == 1)
+		lh->i_mean = new->li_length = (*calc_first_li)(sk);
+	else {
+		cur->li_length = dccp_delta_seqno(cur->li_seqno, new->li_seqno);
+		new->li_length = dccp_delta_seqno(new->li_seqno,
+				  tfrc_rx_hist_last_rcv(rh)->tfrchrx_seqno) + 1;
+		if (lh->counter > (2*LIH_SIZE))
+			lh->counter -= LIH_SIZE;
+
+		tfrc_lh_calc_i_mean(lh);
+	}
+	return 1;
+}
+EXPORT_SYMBOL_GPL(tfrc_lh_interval_add);
+
+int __init tfrc_li_init(void)
+{
+	tfrc_lh_slab = kmem_cache_create("tfrc_li_hist",
+					 sizeof(struct tfrc_loss_interval), 0,
+					 SLAB_HWCACHE_ALIGN, NULL);
+	return tfrc_lh_slab == NULL ? -ENOBUFS : 0;
+}
+
+void tfrc_li_exit(void)
+{
+	if (tfrc_lh_slab != NULL) {
+		kmem_cache_destroy(tfrc_lh_slab);
+		tfrc_lh_slab = NULL;
+	}
+}
diff --git a/net/dccp/ccids/lib/loss_interval.h b/net/dccp/ccids/lib/loss_interval.h
new file mode 100644
index 0000000..246018a
--- /dev/null
+++ b/net/dccp/ccids/lib/loss_interval.h
@@ -0,0 +1,75 @@
+#ifndef _DCCP_LI_HIST_
+#define _DCCP_LI_HIST_
+/*
+ *  net/dccp/ccids/lib/loss_interval.h
+ *
+ *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
+ *  Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
+ *  Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz>
+ *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the Free
+ *  Software Foundation; either version 2 of the License, or (at your option)
+ *  any later version.
+ */
+#include <linux/ktime.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+
+/*
+ * Number of loss intervals (RFC 4342, 8.6.1). The history size is one more than
+ * NINTERVAL, since the `open' interval I_0 is always stored as the first entry.
+ */
+#define NINTERVAL	8
+#define LIH_SIZE	(NINTERVAL + 1)
+
+/**
+ *  tfrc_loss_interval  -  Loss history record for TFRC-based protocols
+ *  @li_seqno:		Highest received seqno before the start of loss
+ *  @li_ccval:		The CCVal belonging to @li_seqno
+ *  @li_is_closed:	Whether @li_seqno is older than 1 RTT
+ *  @li_length:		Loss interval sequence length
+ */
+struct tfrc_loss_interval {
+	u64		 li_seqno:48,
+			 li_ccval:4,
+			 li_is_closed:1;
+	u32		 li_length;
+};
+
+/**
+ *  tfrc_loss_hist  -  Loss record database
+ *  @ring:	Circular queue managed in LIFO manner
+ *  @counter:	Current count of entries (can be more than %LIH_SIZE)
+ *  @i_mean:	Current Average Loss Interval [RFC 3448, 5.4]
+ */
+struct tfrc_loss_hist {
+	struct tfrc_loss_interval	*ring[LIH_SIZE];
+	u8				counter;
+	u32				i_mean;
+};
+
+static inline void tfrc_lh_init(struct tfrc_loss_hist *lh)
+{
+	memset(lh, 0, sizeof(struct tfrc_loss_hist));
+}
+
+static inline u8 tfrc_lh_is_initialised(struct tfrc_loss_hist *lh)
+{
+	return lh->counter > 0;
+}
+
+static inline u8 tfrc_lh_length(struct tfrc_loss_hist *lh)
+{
+	return min(lh->counter, (u8)LIH_SIZE);
+}
+
+struct tfrc_rx_hist;
+
+extern int  tfrc_lh_interval_add(struct tfrc_loss_hist *, struct tfrc_rx_hist *,
+				 u32 (*first_li)(struct sock *), struct sock *);
+extern u8   tfrc_lh_update_i_mean(struct tfrc_loss_hist *lh, struct sk_buff *);
+extern void tfrc_lh_cleanup(struct tfrc_loss_hist *lh);
+
+#endif /* _DCCP_LI_HIST_ */
diff --git a/net/dccp/ccids/lib/packet_history.c b/net/dccp/ccids/lib/packet_history.c
new file mode 100644
index 0000000..6cc108a
--- /dev/null
+++ b/net/dccp/ccids/lib/packet_history.c
@@ -0,0 +1,498 @@
+/*
+ *  net/dccp/packet_history.c
+ *
+ *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
+ *  Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
+ *
+ *  An implementation of the DCCP protocol
+ *
+ *  This code has been developed by the University of Waikato WAND
+ *  research group. For further information please see http://www.wand.net.nz/
+ *  or e-mail Ian McDonald - ian.mcdonald@jandi.co.nz
+ *
+ *  This code also uses code from Lulea University, rereleased as GPL by its
+ *  authors:
+ *  Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
+ *
+ *  Changes to meet Linux coding standards, to make it meet latest ccid3 draft
+ *  and to make it work as a loadable module in the DCCP stack written by
+ *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
+ *
+ *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/string.h>
+#include <linux/slab.h>
+#include "packet_history.h"
+#include "../../dccp.h"
+
+/**
+ *  tfrc_tx_hist_entry  -  Simple singly-linked TX history list
+ *  @next:  next oldest entry (LIFO order)
+ *  @seqno: sequence number of this entry
+ *  @stamp: send time of packet with sequence number @seqno
+ */
+struct tfrc_tx_hist_entry {
+	struct tfrc_tx_hist_entry *next;
+	u64			  seqno;
+	ktime_t			  stamp;
+};
+
+/*
+ * Transmitter History Routines
+ */
+static struct kmem_cache *tfrc_tx_hist_slab;
+
+int __init tfrc_tx_packet_history_init(void)
+{
+	tfrc_tx_hist_slab = kmem_cache_create("tfrc_tx_hist",
+					      sizeof(struct tfrc_tx_hist_entry),
+					      0, SLAB_HWCACHE_ALIGN, NULL);
+	return tfrc_tx_hist_slab == NULL ? -ENOBUFS : 0;
+}
+
+void tfrc_tx_packet_history_exit(void)
+{
+	if (tfrc_tx_hist_slab != NULL) {
+		kmem_cache_destroy(tfrc_tx_hist_slab);
+		tfrc_tx_hist_slab = NULL;
+	}
+}
+
+static struct tfrc_tx_hist_entry *
+	tfrc_tx_hist_find_entry(struct tfrc_tx_hist_entry *head, u64 seqno)
+{
+	while (head != NULL && head->seqno != seqno)
+		head = head->next;
+
+	return head;
+}
+
+int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno)
+{
+	struct tfrc_tx_hist_entry *entry = kmem_cache_alloc(tfrc_tx_hist_slab, gfp_any());
+
+	if (entry == NULL)
+		return -ENOBUFS;
+	entry->seqno = seqno;
+	entry->stamp = ktime_get_real();
+	entry->next  = *headp;
+	*headp	     = entry;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(tfrc_tx_hist_add);
+
+void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp)
+{
+	struct tfrc_tx_hist_entry *head = *headp;
+
+	while (head != NULL) {
+		struct tfrc_tx_hist_entry *next = head->next;
+
+		kmem_cache_free(tfrc_tx_hist_slab, head);
+		head = next;
+	}
+
+	*headp = NULL;
+}
+EXPORT_SYMBOL_GPL(tfrc_tx_hist_purge);
+
+u32 tfrc_tx_hist_rtt(struct tfrc_tx_hist_entry *head, const u64 seqno,
+		     const ktime_t now)
+{
+	u32 rtt = 0;
+	struct tfrc_tx_hist_entry *packet = tfrc_tx_hist_find_entry(head, seqno);
+
+	if (packet != NULL) {
+		rtt = ktime_us_delta(now, packet->stamp);
+		/*
+		 * Garbage-collect older (irrelevant) entries:
+		 */
+		tfrc_tx_hist_purge(&packet->next);
+	}
+
+	return rtt;
+}
+EXPORT_SYMBOL_GPL(tfrc_tx_hist_rtt);
+
+
+/*
+ * 	Receiver History Routines
+ */
+static struct kmem_cache *tfrc_rx_hist_slab;
+
+int __init tfrc_rx_packet_history_init(void)
+{
+	tfrc_rx_hist_slab = kmem_cache_create("tfrc_rxh_cache",
+					      sizeof(struct tfrc_rx_hist_entry),
+					      0, SLAB_HWCACHE_ALIGN, NULL);
+	return tfrc_rx_hist_slab == NULL ? -ENOBUFS : 0;
+}
+
+void tfrc_rx_packet_history_exit(void)
+{
+	if (tfrc_rx_hist_slab != NULL) {
+		kmem_cache_destroy(tfrc_rx_hist_slab);
+		tfrc_rx_hist_slab = NULL;
+	}
+}
+
+static inline void tfrc_rx_hist_entry_from_skb(struct tfrc_rx_hist_entry *entry,
+					       const struct sk_buff *skb,
+					       const u64 ndp)
+{
+	const struct dccp_hdr *dh = dccp_hdr(skb);
+
+	entry->tfrchrx_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
+	entry->tfrchrx_ccval = dh->dccph_ccval;
+	entry->tfrchrx_type  = dh->dccph_type;
+	entry->tfrchrx_ndp   = ndp;
+	entry->tfrchrx_tstamp = ktime_get_real();
+}
+
+void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,
+			     const struct sk_buff *skb,
+			     const u64 ndp)
+{
+	struct tfrc_rx_hist_entry *entry = tfrc_rx_hist_last_rcv(h);
+
+	tfrc_rx_hist_entry_from_skb(entry, skb, ndp);
+}
+EXPORT_SYMBOL_GPL(tfrc_rx_hist_add_packet);
+
+/* has the packet contained in skb been seen before? */
+int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb)
+{
+	const u64 seq = DCCP_SKB_CB(skb)->dccpd_seq;
+	int i;
+
+	if (dccp_delta_seqno(tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, seq) <= 0)
+		return 1;
+
+	for (i = 1; i <= h->loss_count; i++)
+		if (tfrc_rx_hist_entry(h, i)->tfrchrx_seqno == seq)
+			return 1;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(tfrc_rx_hist_duplicate);
+
+static void tfrc_rx_hist_swap(struct tfrc_rx_hist *h, const u8 a, const u8 b)
+{
+	const u8 idx_a = tfrc_rx_hist_index(h, a),
+		 idx_b = tfrc_rx_hist_index(h, b);
+	struct tfrc_rx_hist_entry *tmp = h->ring[idx_a];
+
+	h->ring[idx_a] = h->ring[idx_b];
+	h->ring[idx_b] = tmp;
+}
+
+/*
+ * Private helper functions for loss detection.
+ *
+ * In the descriptions, `Si' refers to the sequence number of entry number i,
+ * whose NDP count is `Ni' (lower case is used for variables).
+ * Note: All __xxx_loss functions expect that a test against duplicates has been
+ *       performed already: the seqno of the skb must not be less than the seqno
+ *       of loss_prev; and it must not equal that of any valid history entry.
+ */
+static void __do_track_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u64 n1)
+{
+	u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno,
+	    s1 = DCCP_SKB_CB(skb)->dccpd_seq;
+
+	if (!dccp_loss_free(s0, s1, n1)) {	/* gap between S0 and S1 */
+		h->loss_count = 1;
+		tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n1);
+	}
+}
+
+static void __one_after_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u32 n2)
+{
+	u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno,
+	    s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno,
+	    s2 = DCCP_SKB_CB(skb)->dccpd_seq;
+
+	if (likely(dccp_delta_seqno(s1, s2) > 0)) {	/* S1  <  S2 */
+		h->loss_count = 2;
+		tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 2), skb, n2);
+		return;
+	}
+
+	/* S0  <  S2  <  S1 */
+
+	if (dccp_loss_free(s0, s2, n2)) {
+		u64 n1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_ndp;
+
+		if (dccp_loss_free(s2, s1, n1)) {
+			/* hole is filled: S0, S2, and S1 are consecutive */
+			h->loss_count = 0;
+			h->loss_start = tfrc_rx_hist_index(h, 1);
+		} else
+			/* gap between S2 and S1: just update loss_prev */
+			tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_loss_prev(h), skb, n2);
+
+	} else {	/* gap between S0 and S2 */
+		/*
+		 * Reorder history to insert S2 between S0 and S1
+		 */
+		tfrc_rx_hist_swap(h, 0, 3);
+		h->loss_start = tfrc_rx_hist_index(h, 3);
+		tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n2);
+		h->loss_count = 2;
+	}
+}
+
+/* return 1 if a new loss event has been identified */
+static int __two_after_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u32 n3)
+{
+	u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno,
+	    s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno,
+	    s2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_seqno,
+	    s3 = DCCP_SKB_CB(skb)->dccpd_seq;
+
+	if (likely(dccp_delta_seqno(s2, s3) > 0)) {	/* S2  <  S3 */
+		h->loss_count = 3;
+		tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 3), skb, n3);
+		return 1;
+	}
+
+	/* S3  <  S2 */
+
+	if (dccp_delta_seqno(s1, s3) > 0) {		/* S1  <  S3  <  S2 */
+		/*
+		 * Reorder history to insert S3 between S1 and S2
+		 */
+		tfrc_rx_hist_swap(h, 2, 3);
+		tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 2), skb, n3);
+		h->loss_count = 3;
+		return 1;
+	}
+
+	/* S0  <  S3  <  S1 */
+
+	if (dccp_loss_free(s0, s3, n3)) {
+		u64 n1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_ndp;
+
+		if (dccp_loss_free(s3, s1, n1)) {
+			/* hole between S0 and S1 filled by S3 */
+			u64 n2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_ndp;
+
+			if (dccp_loss_free(s1, s2, n2)) {
+				/* entire hole filled by S0, S3, S1, S2 */
+				h->loss_start = tfrc_rx_hist_index(h, 2);
+				h->loss_count = 0;
+			} else {
+				/* gap remains between S1 and S2 */
+				h->loss_start = tfrc_rx_hist_index(h, 1);
+				h->loss_count = 1;
+			}
+
+		} else /* gap exists between S3 and S1, loss_count stays at 2 */
+			tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_loss_prev(h), skb, n3);
+
+		return 0;
+	}
+
+	/*
+	 * The remaining case:  S0  <  S3  <  S1  <  S2;  gap between S0 and S3
+	 * Reorder history to insert S3 between S0 and S1.
+	 */
+	tfrc_rx_hist_swap(h, 0, 3);
+	h->loss_start = tfrc_rx_hist_index(h, 3);
+	tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n3);
+	h->loss_count = 3;
+
+	return 1;
+}
+
+/* recycle RX history records to continue loss detection if necessary */
+static void __three_after_loss(struct tfrc_rx_hist *h)
+{
+	/*
+	 * At this stage we know already that there is a gap between S0 and S1
+	 * (since S0 was the highest sequence number received before detecting
+	 * the loss). To recycle the loss record, it is	thus only necessary to
+	 * check for other possible gaps between S1/S2 and between S2/S3.
+	 */
+	u64 s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno,
+	    s2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_seqno,
+	    s3 = tfrc_rx_hist_entry(h, 3)->tfrchrx_seqno;
+	u64 n2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_ndp,
+	    n3 = tfrc_rx_hist_entry(h, 3)->tfrchrx_ndp;
+
+	if (dccp_loss_free(s1, s2, n2)) {
+
+		if (dccp_loss_free(s2, s3, n3)) {
+			/* no gap between S2 and S3: entire hole is filled */
+			h->loss_start = tfrc_rx_hist_index(h, 3);
+			h->loss_count = 0;
+		} else {
+			/* gap between S2 and S3 */
+			h->loss_start = tfrc_rx_hist_index(h, 2);
+			h->loss_count = 1;
+		}
+
+	} else {	/* gap between S1 and S2 */
+		h->loss_start = tfrc_rx_hist_index(h, 1);
+		h->loss_count = 2;
+	}
+}
+
+/**
+ *  tfrc_rx_handle_loss  -  Loss detection and further processing
+ *  @h:		    The non-empty RX history object
+ *  @lh:	    Loss Intervals database to update
+ *  @skb:	    Currently received packet
+ *  @ndp:	    The NDP count belonging to @skb
+ *  @calc_first_li: Caller-dependent computation of first loss interval in @lh
+ *  @sk:	    Used by @calc_first_li (see tfrc_lh_interval_add)
+ *  Chooses action according to pending loss, updates LI database when a new
+ *  loss was detected, and does required post-processing. Returns 1 when caller
+ *  should send feedback, 0 otherwise.
+ *  Since it also takes care of reordering during loss detection and updates the
+ *  records accordingly, the caller should not perform any more RX history
+ *  operations when loss_count is greater than 0 after calling this function.
+ */
+int tfrc_rx_handle_loss(struct tfrc_rx_hist *h,
+			struct tfrc_loss_hist *lh,
+			struct sk_buff *skb, const u64 ndp,
+			u32 (*calc_first_li)(struct sock *), struct sock *sk)
+{
+	int is_new_loss = 0;
+
+	if (h->loss_count == 0) {
+		__do_track_loss(h, skb, ndp);
+	} else if (h->loss_count == 1) {
+		__one_after_loss(h, skb, ndp);
+	} else if (h->loss_count != 2) {
+		DCCP_BUG("invalid loss_count %d", h->loss_count);
+	} else if (__two_after_loss(h, skb, ndp)) {
+		/*
+		 * Update Loss Interval database and recycle RX records
+		 */
+		is_new_loss = tfrc_lh_interval_add(lh, h, calc_first_li, sk);
+		__three_after_loss(h);
+	}
+	return is_new_loss;
+}
+EXPORT_SYMBOL_GPL(tfrc_rx_handle_loss);
+
+int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h)
+{
+	int i;
+
+	for (i = 0; i <= TFRC_NDUPACK; i++) {
+		h->ring[i] = kmem_cache_alloc(tfrc_rx_hist_slab, GFP_ATOMIC);
+		if (h->ring[i] == NULL)
+			goto out_free;
+	}
+
+	h->loss_count = h->loss_start = 0;
+	return 0;
+
+out_free:
+	while (i-- != 0) {
+		kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]);
+		h->ring[i] = NULL;
+	}
+	return -ENOBUFS;
+}
+EXPORT_SYMBOL_GPL(tfrc_rx_hist_alloc);
+
+void tfrc_rx_hist_purge(struct tfrc_rx_hist *h)
+{
+	int i;
+
+	for (i = 0; i <= TFRC_NDUPACK; ++i)
+		if (h->ring[i] != NULL) {
+			kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]);
+			h->ring[i] = NULL;
+		}
+}
+EXPORT_SYMBOL_GPL(tfrc_rx_hist_purge);
+
+/**
+ * tfrc_rx_hist_rtt_last_s - reference entry to compute RTT samples against
+ */
+static inline struct tfrc_rx_hist_entry *
+			tfrc_rx_hist_rtt_last_s(const struct tfrc_rx_hist *h)
+{
+	return h->ring[0];
+}
+
+/**
+ * tfrc_rx_hist_rtt_prev_s: previously suitable (wrt rtt_last_s) RTT-sampling entry
+ */
+static inline struct tfrc_rx_hist_entry *
+			tfrc_rx_hist_rtt_prev_s(const struct tfrc_rx_hist *h)
+{
+	return h->ring[h->rtt_sample_prev];
+}
+
+/**
+ * tfrc_rx_hist_sample_rtt  -  Sample RTT from timestamp / CCVal
+ * Based on ideas presented in RFC 4342, 8.1. Returns 0 if it was not able
+ * to compute a sample with given data - calling function should check this.
+ */
+u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h, const struct sk_buff *skb)
+{
+	u32 sample = 0,
+	    delta_v = SUB16(dccp_hdr(skb)->dccph_ccval,
+			    tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval);
+
+	if (delta_v < 1 || delta_v > 4) {	/* unsuitable CCVal delta */
+		if (h->rtt_sample_prev == 2) {	/* previous candidate stored */
+			sample = SUB16(tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_ccval,
+				       tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval);
+			if (sample)
+				sample = 4 / sample *
+				         ktime_us_delta(tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_tstamp,
+							tfrc_rx_hist_rtt_last_s(h)->tfrchrx_tstamp);
+			else    /*
+				 * FIXME: This condition is in principle not
+				 * possible but occurs when CCID is used for
+				 * two-way data traffic. I have tried to trace
+				 * it, but the cause does not seem to be here.
+				 */
+				DCCP_BUG("please report to dccp@vger.kernel.org"
+					 " => prev = %u, last = %u",
+					 tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_ccval,
+					 tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval);
+		} else if (delta_v < 1) {
+			h->rtt_sample_prev = 1;
+			goto keep_ref_for_next_time;
+		}
+
+	} else if (delta_v == 4) /* optimal match */
+		sample = ktime_to_us(net_timedelta(tfrc_rx_hist_rtt_last_s(h)->tfrchrx_tstamp));
+	else {			 /* suboptimal match */
+		h->rtt_sample_prev = 2;
+		goto keep_ref_for_next_time;
+	}
+
+	if (unlikely(sample > DCCP_SANE_RTT_MAX)) {
+		DCCP_WARN("RTT sample %u too large, using max\n", sample);
+		sample = DCCP_SANE_RTT_MAX;
+	}
+
+	h->rtt_sample_prev = 0;	       /* use current entry as next reference */
+keep_ref_for_next_time:
+
+	return sample;
+}
+EXPORT_SYMBOL_GPL(tfrc_rx_hist_sample_rtt);
diff --git a/net/dccp/ccids/lib/packet_history.h b/net/dccp/ccids/lib/packet_history.h
new file mode 100644
index 0000000..461cc91
--- /dev/null
+++ b/net/dccp/ccids/lib/packet_history.h
@@ -0,0 +1,143 @@
+/*
+ *  Packet RX/TX history data structures and routines for TFRC-based protocols.
+ *
+ *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
+ *  Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
+ *
+ *  This code has been developed by the University of Waikato WAND
+ *  research group. For further information please see http://www.wand.net.nz/
+ *  or e-mail Ian McDonald - ian.mcdonald@jandi.co.nz
+ *
+ *  This code also uses code from Lulea University, rereleased as GPL by its
+ *  authors:
+ *  Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
+ *
+ *  Changes to meet Linux coding standards, to make it meet latest ccid3 draft
+ *  and to make it work as a loadable module in the DCCP stack written by
+ *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
+ *
+ *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef _DCCP_PKT_HIST_
+#define _DCCP_PKT_HIST_
+
+#include <linux/list.h>
+#include <linux/slab.h>
+#include "tfrc.h"
+
+struct tfrc_tx_hist_entry;
+
+extern int  tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno);
+extern void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp);
+extern u32  tfrc_tx_hist_rtt(struct tfrc_tx_hist_entry *head,
+			     const u64 seqno, const ktime_t now);
+
+/* Subtraction a-b modulo-16, respects circular wrap-around */
+#define SUB16(a, b) (((a) + 16 - (b)) & 0xF)
+
+/* Number of packets to wait after a missing packet (RFC 4342, 6.1) */
+#define TFRC_NDUPACK 3
+
+/**
+ * tfrc_rx_hist_entry - Store information about a single received packet
+ * @tfrchrx_seqno:	DCCP packet sequence number
+ * @tfrchrx_ccval:	window counter value of packet (RFC 4342, 8.1)
+ * @tfrchrx_ndp:	the NDP count (if any) of the packet
+ * @tfrchrx_tstamp:	actual receive time of packet
+ */
+struct tfrc_rx_hist_entry {
+	u64		 tfrchrx_seqno:48,
+			 tfrchrx_ccval:4,
+			 tfrchrx_type:4;
+	u64		 tfrchrx_ndp:48;
+	ktime_t		 tfrchrx_tstamp;
+};
+
+/**
+ * tfrc_rx_hist  -  RX history structure for TFRC-based protocols
+ *
+ * @ring:		Packet history for RTT sampling and loss detection
+ * @loss_count:		Number of entries in circular history
+ * @loss_start:		Movable index (for loss detection)
+ * @rtt_sample_prev:	Used during RTT sampling, points to candidate entry
+ */
+struct tfrc_rx_hist {
+	struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1];
+	u8			  loss_count:2,
+				  loss_start:2;
+#define rtt_sample_prev		  loss_start
+};
+
+/**
+ * tfrc_rx_hist_index - index to reach n-th entry after loss_start
+ */
+static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n)
+{
+	return (h->loss_start + n) & TFRC_NDUPACK;
+}
+
+/**
+ * tfrc_rx_hist_last_rcv - entry with highest-received-seqno so far
+ */
+static inline struct tfrc_rx_hist_entry *
+			tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h)
+{
+	return h->ring[tfrc_rx_hist_index(h, h->loss_count)];
+}
+
+/**
+ * tfrc_rx_hist_entry - return the n-th history entry after loss_start
+ */
+static inline struct tfrc_rx_hist_entry *
+			tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n)
+{
+	return h->ring[tfrc_rx_hist_index(h, n)];
+}
+
+/**
+ * tfrc_rx_hist_loss_prev - entry with highest-received-seqno before loss was detected
+ */
+static inline struct tfrc_rx_hist_entry *
+			tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h)
+{
+	return h->ring[h->loss_start];
+}
+
+/* indicate whether previously a packet was detected missing */
+static inline bool tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
+{
+	return h->loss_count > 0;
+}
+
+extern void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,
+				    const struct sk_buff *skb, const u64 ndp);
+
+extern int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb);
+
+struct tfrc_loss_hist;
+extern int  tfrc_rx_handle_loss(struct tfrc_rx_hist *h,
+				struct tfrc_loss_hist *lh,
+				struct sk_buff *skb, const u64 ndp,
+				u32 (*first_li)(struct sock *sk),
+				struct sock *sk);
+extern u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h,
+				   const struct sk_buff *skb);
+extern int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h);
+extern void tfrc_rx_hist_purge(struct tfrc_rx_hist *h);
+
+#endif /* _DCCP_PKT_HIST_ */
diff --git a/net/dccp/ccids/lib/tfrc.c b/net/dccp/ccids/lib/tfrc.c
new file mode 100644
index 0000000..1859162
--- /dev/null
+++ b/net/dccp/ccids/lib/tfrc.c
@@ -0,0 +1,55 @@
+/*
+ * TFRC: main module holding the pieces of the TFRC library together
+ *
+ * Copyright (c) 2007 The University of Aberdeen, Scotland, UK
+ * Copyright (c) 2007 Arnaldo Carvalho de Melo <acme@redhat.com>
+ */
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include "tfrc.h"
+
+#ifdef CONFIG_IP_DCCP_TFRC_DEBUG
+int tfrc_debug;
+module_param(tfrc_debug, bool, 0644);
+MODULE_PARM_DESC(tfrc_debug, "Enable debug messages");
+#endif
+
+static int __init tfrc_module_init(void)
+{
+	int rc = tfrc_li_init();
+
+	if (rc)
+		goto out;
+
+	rc = tfrc_tx_packet_history_init();
+	if (rc)
+		goto out_free_loss_intervals;
+
+	rc = tfrc_rx_packet_history_init();
+	if (rc)
+		goto out_free_tx_history;
+	return 0;
+
+out_free_tx_history:
+	tfrc_tx_packet_history_exit();
+out_free_loss_intervals:
+	tfrc_li_exit();
+out:
+	return rc;
+}
+
+static void __exit tfrc_module_exit(void)
+{
+	tfrc_rx_packet_history_exit();
+	tfrc_tx_packet_history_exit();
+	tfrc_li_exit();
+}
+
+module_init(tfrc_module_init);
+module_exit(tfrc_module_exit);
+
+MODULE_AUTHOR("Gerrit Renker <gerrit@erg.abdn.ac.uk>, "
+	      "Ian McDonald <ian.mcdonald@jandi.co.nz>, "
+	      "Arnaldo Carvalho de Melo <acme@redhat.com>");
+MODULE_DESCRIPTION("DCCP TFRC library");
+MODULE_LICENSE("GPL");
diff --git a/net/dccp/ccids/lib/tfrc.h b/net/dccp/ccids/lib/tfrc.h
new file mode 100644
index 0000000..ed98575
--- /dev/null
+++ b/net/dccp/ccids/lib/tfrc.h
@@ -0,0 +1,69 @@
+#ifndef _TFRC_H_
+#define _TFRC_H_
+/*
+ *  net/dccp/ccids/lib/tfrc.h
+ *
+ *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
+ *  Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
+ *  Copyright (c) 2005-6 Ian McDonald <ian.mcdonald@jandi.co.nz>
+ *  Copyright (c) 2005   Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *  Copyright (c) 2003   Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ */
+#include <linux/types.h>
+#include <linux/math64.h>
+#include "../../dccp.h"
+/* internal includes that this module exports: */
+#include "loss_interval.h"
+#include "packet_history.h"
+
+#ifdef CONFIG_IP_DCCP_TFRC_DEBUG
+extern int tfrc_debug;
+#define tfrc_pr_debug(format, a...)	DCCP_PR_DEBUG(tfrc_debug, format, ##a)
+#else
+#define tfrc_pr_debug(format, a...)
+#endif
+
+/* integer-arithmetic divisions of type (a * 1000000)/b */
+static inline u64 scaled_div(u64 a, u64 b)
+{
+	BUG_ON(b==0);
+	return div64_u64(a * 1000000, b);
+}
+
+static inline u32 scaled_div32(u64 a, u64 b)
+{
+	u64 result = scaled_div(a, b);
+
+	if (result > UINT_MAX) {
+		DCCP_CRIT("Overflow: %llu/%llu > UINT_MAX",
+			  (unsigned long long)a, (unsigned long long)b);
+		return UINT_MAX;
+	}
+	return result;
+}
+
+/**
+ * tfrc_ewma  -  Exponentially weighted moving average
+ * @weight: Weight to be used as damping factor, in units of 1/10
+ */
+static inline u32 tfrc_ewma(const u32 avg, const u32 newval, const u8 weight)
+{
+	return avg ? (weight * avg + (10 - weight) * newval) / 10 : newval;
+}
+
+extern u32  tfrc_calc_x(u16 s, u32 R, u32 p);
+extern u32  tfrc_calc_x_reverse_lookup(u32 fvalue);
+
+extern int  tfrc_tx_packet_history_init(void);
+extern void tfrc_tx_packet_history_exit(void);
+extern int  tfrc_rx_packet_history_init(void);
+extern void tfrc_rx_packet_history_exit(void);
+
+extern int  tfrc_li_init(void);
+extern void tfrc_li_exit(void);
+#endif /* _TFRC_H_ */
diff --git a/net/dccp/ccids/lib/tfrc_equation.c b/net/dccp/ccids/lib/tfrc_equation.c
new file mode 100644
index 0000000..2f20a29
--- /dev/null
+++ b/net/dccp/ccids/lib/tfrc_equation.c
@@ -0,0 +1,697 @@
+/*
+ *  net/dccp/ccids/lib/tfrc_equation.c
+ *
+ *  Copyright (c) 2005 The University of Waikato, Hamilton, New Zealand.
+ *  Copyright (c) 2005 Ian McDonald <ian.mcdonald@jandi.co.nz>
+ *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *  Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include "../../dccp.h"
+#include "tfrc.h"
+
+#define TFRC_CALC_X_ARRSIZE 500
+#define TFRC_CALC_X_SPLIT   50000	/* 0.05 * 1000000, details below */
+#define TFRC_SMALLEST_P	    (TFRC_CALC_X_SPLIT/TFRC_CALC_X_ARRSIZE)
+
+/*
+  TFRC TCP Reno Throughput Equation Lookup Table for f(p)
+
+  The following two-column lookup table implements a part of the TCP throughput
+  equation from [RFC 3448, sec. 3.1]:
+
+				     s
+  X_calc  =  --------------------------------------------------------------
+	     R * sqrt(2*b*p/3) + (3 * t_RTO * sqrt(3*b*p/8) * (p + 32*p^3))
+
+  Where:
+	X      is the transmit rate in bytes/second
+	s      is the packet size in bytes
+	R      is the round trip time in seconds
+	p      is the loss event rate, between 0 and 1.0, of the number of loss
+		      events as a fraction of the number of packets transmitted
+	t_RTO  is the TCP retransmission timeout value in seconds
+	b      is the number of packets acknowledged by a single TCP ACK
+
+  We can assume that b = 1 and t_RTO is 4 * R. The equation now becomes:
+
+				     s
+  X_calc  =  -------------------------------------------------------
+	     R * sqrt(p*2/3) + (12 * R * sqrt(p*3/8) * (p + 32*p^3))
+
+  which we can break down into:
+
+		      s
+	X_calc  =  ---------
+		    R * f(p)
+
+  where f(p) is given for 0 < p <= 1 by:
+
+	f(p)  =  sqrt(2*p/3) + 12 * sqrt(3*p/8) *  (p + 32*p^3)
+
+  Since this is kernel code, floating-point arithmetic is avoided in favour of
+  integer arithmetic. This means that nearly all fractional parameters are
+  scaled by 1000000:
+    * the parameters p and R
+    * the return result f(p)
+  The lookup table therefore actually tabulates the following function g(q):
+
+	g(q)  =  1000000 * f(q/1000000)
+
+  Hence, when p <= 1, q must be less than or equal to 1000000. To achieve finer
+  granularity for the practically more relevant case of small values of p (up to
+  5%), the second column is used; the first one ranges up to 100%.  This split
+  corresponds to the value of q = TFRC_CALC_X_SPLIT. At the same time this also
+  determines the smallest resolution possible with this lookup table:
+
+    TFRC_SMALLEST_P   =  TFRC_CALC_X_SPLIT / TFRC_CALC_X_ARRSIZE
+
+  The entire table is generated by:
+    for(i=0; i < TFRC_CALC_X_ARRSIZE; i++) {
+	lookup[i][0]  =  g((i+1) * 1000000/TFRC_CALC_X_ARRSIZE);
+	lookup[i][1]  =  g((i+1) * TFRC_CALC_X_SPLIT/TFRC_CALC_X_ARRSIZE);
+    }
+
+  With the given configuration, we have, with M = TFRC_CALC_X_ARRSIZE-1,
+    lookup[0][0]  =  g(1000000/(M+1)) 		 =  1000000 * f(0.2%)
+    lookup[M][0]  =  g(1000000)			 =  1000000 * f(100%)
+    lookup[0][1]  =  g(TFRC_SMALLEST_P)		  = 1000000 * f(0.01%)
+    lookup[M][1]  =  g(TFRC_CALC_X_SPLIT)	 =  1000000 * f(5%)
+
+  In summary, the two columns represent f(p) for the following ranges:
+    * The first column is for   0.002  <= p <= 1.0
+    * The second column is for  0.0001 <= p <= 0.05
+  Where the columns overlap, the second (finer-grained) is given preference,
+  i.e. the first column is used only for p >= 0.05.
+ */
+static const u32 tfrc_calc_x_lookup[TFRC_CALC_X_ARRSIZE][2] = {
+	{     37172,   8172 },
+	{     53499,  11567 },
+	{     66664,  14180 },
+	{     78298,  16388 },
+	{     89021,  18339 },
+	{     99147,  20108 },
+	{    108858,  21738 },
+	{    118273,  23260 },
+	{    127474,  24693 },
+	{    136520,  26052 },
+	{    145456,  27348 },
+	{    154316,  28589 },
+	{    163130,  29783 },
+	{    171919,  30935 },
+	{    180704,  32049 },
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+	{ 187007807, 253920 },
+	{ 188391778, 254385 },
+	{ 189783129, 254851 },
+	{ 191181884, 255316 },
+	{ 192588065, 255782 },
+	{ 194001698, 256248 },
+	{ 195422805, 256714 },
+	{ 196851411, 257181 },
+	{ 198287540, 257648 },
+	{ 199731215, 258115 },
+	{ 201182461, 258582 },
+	{ 202641302, 259050 },
+	{ 204107760, 259518 },
+	{ 205581862, 259986 },
+	{ 207063630, 260454 },
+	{ 208553088, 260923 },
+	{ 210050262, 261392 },
+	{ 211555174, 261861 },
+	{ 213067849, 262331 },
+	{ 214588312, 262800 },
+	{ 216116586, 263270 },
+	{ 217652696, 263741 },
+	{ 219196666, 264211 },
+	{ 220748520, 264682 },
+	{ 222308282, 265153 },
+	{ 223875978, 265625 },
+	{ 225451630, 266097 },
+	{ 227035265, 266569 },
+	{ 228626905, 267041 },
+	{ 230226576, 267514 },
+	{ 231834302, 267986 },
+	{ 233450107, 268460 },
+	{ 235074016, 268933 },
+	{ 236706054, 269407 },
+	{ 238346244, 269881 },
+	{ 239994613, 270355 },
+	{ 241651183, 270830 },
+	{ 243315981, 271305 }
+};
+
+/* return largest index i such that fval <= lookup[i][small] */
+static inline u32 tfrc_binsearch(u32 fval, u8 small)
+{
+	u32 try, low = 0, high = TFRC_CALC_X_ARRSIZE - 1;
+
+	while (low < high) {
+		try = (low + high) / 2;
+		if (fval <= tfrc_calc_x_lookup[try][small])
+			high = try;
+		else
+			low  = try + 1;
+	}
+	return high;
+}
+
+/**
+ * tfrc_calc_x - Calculate the send rate as per section 3.1 of RFC3448
+ *
+ *  @s: packet size          in bytes
+ *  @R: RTT                  scaled by 1000000   (i.e., microseconds)
+ *  @p: loss ratio estimate  scaled by 1000000
+ *  Returns X_calc           in bytes per second (not scaled).
+ */
+u32 tfrc_calc_x(u16 s, u32 R, u32 p)
+{
+	u16 index;
+	u32 f;
+	u64 result;
+
+	/* check against invalid parameters and divide-by-zero   */
+	BUG_ON(p >  1000000);		/* p must not exceed 100%   */
+	BUG_ON(p == 0);			/* f(0) = 0, divide by zero */
+	if (R == 0) {			/* possible  divide by zero */
+		DCCP_CRIT("WARNING: RTT is 0, returning maximum X_calc.");
+		return ~0U;
+	}
+
+	if (p <= TFRC_CALC_X_SPLIT) 		{     /* 0.0000 < p <= 0.05   */
+		if (p < TFRC_SMALLEST_P) {	      /* 0.0000 < p <  0.0001 */
+			DCCP_WARN("Value of p (%d) below resolution. "
+				  "Substituting %d\n", p, TFRC_SMALLEST_P);
+			index = 0;
+		} else 				      /* 0.0001 <= p <= 0.05  */
+			index =  p/TFRC_SMALLEST_P - 1;
+
+		f = tfrc_calc_x_lookup[index][1];
+
+	} else {	 			      /* 0.05   <  p <= 1.00  */
+		index = p/(1000000/TFRC_CALC_X_ARRSIZE) - 1;
+
+		f = tfrc_calc_x_lookup[index][0];
+	}
+
+	/*
+	 * Compute X = s/(R*f(p)) in bytes per second.
+	 * Since f(p) and R are both scaled by 1000000, we need to multiply by
+	 * 1000000^2. To avoid overflow, the result is computed in two stages.
+	 * This works under almost all reasonable operational conditions, for a
+	 * wide range of parameters. Yet, should some strange combination of
+	 * parameters result in overflow, the use of scaled_div32 will catch
+	 * this and return UINT_MAX - which is a logically adequate consequence.
+	 */
+	result = scaled_div(s, R);
+	return scaled_div32(result, f);
+}
+
+EXPORT_SYMBOL_GPL(tfrc_calc_x);
+
+/**
+ *  tfrc_calc_x_reverse_lookup  -  try to find p given f(p)
+ *
+ *  @fvalue: function value to match, scaled by 1000000
+ *  Returns closest match for p, also scaled by 1000000
+ */
+u32 tfrc_calc_x_reverse_lookup(u32 fvalue)
+{
+	int index;
+
+	if (fvalue == 0)	/* f(p) = 0  whenever  p = 0 */
+		return 0;
+
+	/* Error cases. */
+	if (fvalue < tfrc_calc_x_lookup[0][1]) {
+		DCCP_WARN("fvalue %u smaller than resolution\n", fvalue);
+		return TFRC_SMALLEST_P;
+	}
+	if (fvalue > tfrc_calc_x_lookup[TFRC_CALC_X_ARRSIZE - 1][0]) {
+		DCCP_WARN("fvalue %u exceeds bounds!\n", fvalue);
+		return 1000000;
+	}
+
+	if (fvalue <= tfrc_calc_x_lookup[TFRC_CALC_X_ARRSIZE - 1][1]) {
+		index = tfrc_binsearch(fvalue, 1);
+		return (index + 1) * TFRC_CALC_X_SPLIT / TFRC_CALC_X_ARRSIZE;
+	}
+
+	/* else ... it must be in the coarse-grained column */
+	index = tfrc_binsearch(fvalue, 0);
+	return (index + 1) * 1000000 / TFRC_CALC_X_ARRSIZE;
+}
+
+EXPORT_SYMBOL_GPL(tfrc_calc_x_reverse_lookup);