Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6: (1436 commits)
  cassini: Use local-mac-address prom property for Cassini MAC address
  net: remove the duplicate #ifdef __KERNEL__
  net: bridge: check the length of skb after nf_bridge_maybe_copy_header()
  netconsole: clarify stopping message
  netconsole: don't announce stopping if nothing happened
  cnic: Fix the type field in SPQ messages
  netfilter: fix export secctx error handling
  netfilter: fix the race when initializing nf_ct_expect_hash_rnd
  ipv4: IP defragmentation must be ECN aware
  net: r6040: Return proper error for r6040_init_one
  dcb: use after free in dcb_flushapp()
  dcb: unlock on error in dcbnl_ieee_get()
  net: ixp4xx_eth: Return proper error for eth_init_one
  include/linux/if_ether.h: Add #define ETH_P_LINK_CTL for HPNA and wlan local tunnel
  net: add POLLPRI to sock_def_readable()
  af_unix: Avoid socket->sk NULL OOPS in stream connect security hooks.
  net_sched: pfifo_head_drop problem
  mac80211: remove stray extern
  mac80211: implement off-channel TX using hw r-o-c offload
  mac80211: implement hardware offload for remain-on-channel
  ...

12 files changed, 755 insertions, 569 deletions

diff --git a/net/dccp/Makefile b/net/dccp/Makefile
index 2991efcc8de..5c8362b037e 100644
--- a/net/dccp/Makefile
+++ b/net/dccp/Makefile
@@ -1,7 +1,7 @@
 obj-$(CONFIG_IP_DCCP) += dccp.o dccp_ipv4.o
 
-dccp-y := ccid.o feat.o input.o minisocks.o options.o output.o proto.o timer.o
-
+dccp-y := ccid.o feat.o input.o minisocks.o options.o output.o proto.o timer.o \
+	  qpolicy.o
 #
 # CCID algorithms to be used by dccp.ko
 #
diff --git a/net/dccp/ackvec.c b/net/dccp/ackvec.c
index 92a6fcb40d7..25b7a8d1ad5 100644
--- a/net/dccp/ackvec.c
+++ b/net/dccp/ackvec.c
@@ -1,444 +1,375 @@
 /*
  *  net/dccp/ackvec.c
  *
- *  An implementation of the DCCP protocol
+ *  An implementation of Ack Vectors for the DCCP protocol
+ *  Copyright (c) 2007 University of Aberdeen, Scotland, UK
  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
  *
  *      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; version 2 of the License;
  */
-
-#include "ackvec.h"
 #include "dccp.h"
-
-#include <linux/init.h>
-#include <linux/errno.h>
 #include <linux/kernel.h>
-#include <linux/skbuff.h>
 #include <linux/slab.h>
 
-#include <net/sock.h>
-
 static struct kmem_cache *dccp_ackvec_slab;
 static struct kmem_cache *dccp_ackvec_record_slab;
 
-static struct dccp_ackvec_record *dccp_ackvec_record_new(void)
+struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
 {
-	struct dccp_ackvec_record *avr =
-			kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC);
+	struct dccp_ackvec *av = kmem_cache_zalloc(dccp_ackvec_slab, priority);
 
-	if (avr != NULL)
-		INIT_LIST_HEAD(&avr->avr_node);
-
-	return avr;
+	if (av != NULL) {
+		av->av_buf_head	= av->av_buf_tail = DCCPAV_MAX_ACKVEC_LEN - 1;
+		INIT_LIST_HEAD(&av->av_records);
+	}
+	return av;
 }
 
-static void dccp_ackvec_record_delete(struct dccp_ackvec_record *avr)
+static void dccp_ackvec_purge_records(struct dccp_ackvec *av)
 {
-	if (unlikely(avr == NULL))
-		return;
-	/* Check if deleting a linked record */
-	WARN_ON(!list_empty(&avr->avr_node));
-	kmem_cache_free(dccp_ackvec_record_slab, avr);
+	struct dccp_ackvec_record *cur, *next;
+
+	list_for_each_entry_safe(cur, next, &av->av_records, avr_node)
+		kmem_cache_free(dccp_ackvec_record_slab, cur);
+	INIT_LIST_HEAD(&av->av_records);
 }
 
-static void dccp_ackvec_insert_avr(struct dccp_ackvec *av,
-				   struct dccp_ackvec_record *avr)
+void dccp_ackvec_free(struct dccp_ackvec *av)
 {
-	/*
-	 * AVRs are sorted by seqno. Since we are sending them in order, we
-	 * just add the AVR at the head of the list.
-	 * -sorbo.
-	 */
-	if (!list_empty(&av->av_records)) {
-		const struct dccp_ackvec_record *head =
-					list_entry(av->av_records.next,
-						   struct dccp_ackvec_record,
-						   avr_node);
-		BUG_ON(before48(avr->avr_ack_seqno, head->avr_ack_seqno));
+	if (likely(av != NULL)) {
+		dccp_ackvec_purge_records(av);
+		kmem_cache_free(dccp_ackvec_slab, av);
 	}
-
-	list_add(&avr->avr_node, &av->av_records);
 }
 
-int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
+/**
+ * dccp_ackvec_update_records  -  Record information about sent Ack Vectors
+ * @av:		Ack Vector records to update
+ * @seqno:	Sequence number of the packet carrying the Ack Vector just sent
+ * @nonce_sum:	The sum of all buffer nonces contained in the Ack Vector
+ */
+int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seqno, u8 nonce_sum)
 {
-	struct dccp_sock *dp = dccp_sk(sk);
-	struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
-	/* Figure out how many options do we need to represent the ackvec */
-	const u8 nr_opts = DIV_ROUND_UP(av->av_vec_len, DCCP_SINGLE_OPT_MAXLEN);
-	u16 len = av->av_vec_len + 2 * nr_opts, i;
-	u32 elapsed_time;
-	const unsigned char *tail, *from;
-	unsigned char *to;
 	struct dccp_ackvec_record *avr;
-	suseconds_t delta;
-
-	if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
-		return -1;
-
-	delta = ktime_us_delta(ktime_get_real(), av->av_time);
-	elapsed_time = delta / 10;
 
-	if (elapsed_time != 0 &&
-	    dccp_insert_option_elapsed_time(skb, elapsed_time))
-		return -1;
-
-	avr = dccp_ackvec_record_new();
+	avr = kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC);
 	if (avr == NULL)
-		return -1;
-
-	DCCP_SKB_CB(skb)->dccpd_opt_len += len;
-
-	to   = skb_push(skb, len);
-	len  = av->av_vec_len;
-	from = av->av_buf + av->av_buf_head;
-	tail = av->av_buf + DCCP_MAX_ACKVEC_LEN;
-
-	for (i = 0; i < nr_opts; ++i) {
-		int copylen = len;
-
-		if (len > DCCP_SINGLE_OPT_MAXLEN)
-			copylen = DCCP_SINGLE_OPT_MAXLEN;
-
-		*to++ = DCCPO_ACK_VECTOR_0;
-		*to++ = copylen + 2;
-
-		/* Check if buf_head wraps */
-		if (from + copylen > tail) {
-			const u16 tailsize = tail - from;
-
-			memcpy(to, from, tailsize);
-			to	+= tailsize;
-			len	-= tailsize;
-			copylen	-= tailsize;
-			from	= av->av_buf;
-		}
-
-		memcpy(to, from, copylen);
-		from += copylen;
-		to   += copylen;
-		len  -= copylen;
-	}
+		return -ENOBUFS;
 
+	avr->avr_ack_seqno  = seqno;
+	avr->avr_ack_ptr    = av->av_buf_head;
+	avr->avr_ack_ackno  = av->av_buf_ackno;
+	avr->avr_ack_nonce  = nonce_sum;
+	avr->avr_ack_runlen = dccp_ackvec_runlen(av->av_buf + av->av_buf_head);
 	/*
-	 *	From RFC 4340, A.2:
-	 *
-	 *	For each acknowledgement it sends, the HC-Receiver will add an
-	 *	acknowledgement record.  ack_seqno will equal the HC-Receiver
-	 *	sequence number it used for the ack packet; ack_ptr will equal
-	 *	buf_head; ack_ackno will equal buf_ackno; and ack_nonce will
-	 *	equal buf_nonce.
+	 * When the buffer overflows, we keep no more than one record. This is
+	 * the simplest way of disambiguating sender-Acks dating from before the
+	 * overflow from sender-Acks which refer to after the overflow; a simple
+	 * solution is preferable here since we are handling an exception.
 	 */
-	avr->avr_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
-	avr->avr_ack_ptr   = av->av_buf_head;
-	avr->avr_ack_ackno = av->av_buf_ackno;
-	avr->avr_ack_nonce = av->av_buf_nonce;
-	avr->avr_sent_len  = av->av_vec_len;
-
-	dccp_ackvec_insert_avr(av, avr);
+	if (av->av_overflow)
+		dccp_ackvec_purge_records(av);
+	/*
+	 * Since GSS is incremented for each packet, the list is automatically
+	 * arranged in descending order of @ack_seqno.
+	 */
+	list_add(&avr->avr_node, &av->av_records);
 
-	dccp_pr_debug("%s ACK Vector 0, len=%d, ack_seqno=%llu, "
-		      "ack_ackno=%llu\n",
-		      dccp_role(sk), avr->avr_sent_len,
+	dccp_pr_debug("Added Vector, ack_seqno=%llu, ack_ackno=%llu (rl=%u)\n",
 		      (unsigned long long)avr->avr_ack_seqno,
-		      (unsigned long long)avr->avr_ack_ackno);
+		      (unsigned long long)avr->avr_ack_ackno,
+		      avr->avr_ack_runlen);
 	return 0;
 }
 
-struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
+static struct dccp_ackvec_record *dccp_ackvec_lookup(struct list_head *av_list,
+						     const u64 ackno)
 {
-	struct dccp_ackvec *av = kmem_cache_alloc(dccp_ackvec_slab, priority);
-
-	if (av != NULL) {
-		av->av_buf_head	 = DCCP_MAX_ACKVEC_LEN - 1;
-		av->av_buf_ackno = UINT48_MAX + 1;
-		av->av_buf_nonce = 0;
-		av->av_time	 = ktime_set(0, 0);
-		av->av_vec_len	 = 0;
-		INIT_LIST_HEAD(&av->av_records);
+	struct dccp_ackvec_record *avr;
+	/*
+	 * Exploit that records are inserted in descending order of sequence
+	 * number, start with the oldest record first. If @ackno is `before'
+	 * the earliest ack_ackno, the packet is too old to be considered.
+	 */
+	list_for_each_entry_reverse(avr, av_list, avr_node) {
+		if (avr->avr_ack_seqno == ackno)
+			return avr;
+		if (before48(ackno, avr->avr_ack_seqno))
+			break;
 	}
-
-	return av;
+	return NULL;
 }
 
-void dccp_ackvec_free(struct dccp_ackvec *av)
+/*
+ * Buffer index and length computation using modulo-buffersize arithmetic.
+ * Note that, as pointers move from right to left, head is `before' tail.
+ */
+static inline u16 __ackvec_idx_add(const u16 a, const u16 b)
 {
-	if (unlikely(av == NULL))
-		return;
-
-	if (!list_empty(&av->av_records)) {
-		struct dccp_ackvec_record *avr, *next;
-
-		list_for_each_entry_safe(avr, next, &av->av_records, avr_node) {
-			list_del_init(&avr->avr_node);
-			dccp_ackvec_record_delete(avr);
-		}
-	}
-
-	kmem_cache_free(dccp_ackvec_slab, av);
+	return (a + b) % DCCPAV_MAX_ACKVEC_LEN;
 }
 
-static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av,
-				   const u32 index)
+static inline u16 __ackvec_idx_sub(const u16 a, const u16 b)
 {
-	return av->av_buf[index] & DCCP_ACKVEC_STATE_MASK;
+	return __ackvec_idx_add(a, DCCPAV_MAX_ACKVEC_LEN - b);
 }
 
-static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av,
-				 const u32 index)
+u16 dccp_ackvec_buflen(const struct dccp_ackvec *av)
 {
-	return av->av_buf[index] & DCCP_ACKVEC_LEN_MASK;
+	if (unlikely(av->av_overflow))
+		return DCCPAV_MAX_ACKVEC_LEN;
+	return __ackvec_idx_sub(av->av_buf_tail, av->av_buf_head);
 }
 
-/*
- * If several packets are missing, the HC-Receiver may prefer to enter multiple
- * bytes with run length 0, rather than a single byte with a larger run length;
- * this simplifies table updates if one of the missing packets arrives.
+/**
+ * dccp_ackvec_update_old  -  Update previous state as per RFC 4340, 11.4.1
+ * @av:		non-empty buffer to update
+ * @distance:   negative or zero distance of @seqno from buf_ackno downward
+ * @seqno:	the (old) sequence number whose record is to be updated
+ * @state:	state in which packet carrying @seqno was received
  */
-static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av,
-						 const unsigned int packets,
-						 const unsigned char state)
+static void dccp_ackvec_update_old(struct dccp_ackvec *av, s64 distance,
+				   u64 seqno, enum dccp_ackvec_states state)
 {
-	long gap;
-	long new_head;
+	u16 ptr = av->av_buf_head;
 
-	if (av->av_vec_len + packets > DCCP_MAX_ACKVEC_LEN)
-		return -ENOBUFS;
+	BUG_ON(distance > 0);
+	if (unlikely(dccp_ackvec_is_empty(av)))
+		return;
 
-	gap	 = packets - 1;
-	new_head = av->av_buf_head - packets;
+	do {
+		u8 runlen = dccp_ackvec_runlen(av->av_buf + ptr);
 
-	if (new_head < 0) {
-		if (gap > 0) {
-			memset(av->av_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED,
-			       gap + new_head + 1);
-			gap = -new_head;
+		if (distance + runlen >= 0) {
+			/*
+			 * Only update the state if packet has not been received
+			 * yet. This is OK as per the second table in RFC 4340,
+			 * 11.4.1; i.e. here we are using the following table:
+			 *                     RECEIVED
+			 *                      0   1   3
+			 *              S     +---+---+---+
+			 *              T   0 | 0 | 0 | 0 |
+			 *              O     +---+---+---+
+			 *              R   1 | 1 | 1 | 1 |
+			 *              E     +---+---+---+
+			 *              D   3 | 0 | 1 | 3 |
+			 *                    +---+---+---+
+			 * The "Not Received" state was set by reserve_seats().
+			 */
+			if (av->av_buf[ptr] == DCCPAV_NOT_RECEIVED)
+				av->av_buf[ptr] = state;
+			else
+				dccp_pr_debug("Not changing %llu state to %u\n",
+					      (unsigned long long)seqno, state);
+			break;
 		}
-		new_head += DCCP_MAX_ACKVEC_LEN;
-	}
 
-	av->av_buf_head = new_head;
+		distance += runlen + 1;
+		ptr	  = __ackvec_idx_add(ptr, 1);
 
-	if (gap > 0)
-		memset(av->av_buf + av->av_buf_head + 1,
-		       DCCP_ACKVEC_STATE_NOT_RECEIVED, gap);
+	} while (ptr != av->av_buf_tail);
+}
 
-	av->av_buf[av->av_buf_head] = state;
-	av->av_vec_len += packets;
-	return 0;
+/* Mark @num entries after buf_head as "Not yet received". */
+static void dccp_ackvec_reserve_seats(struct dccp_ackvec *av, u16 num)
+{
+	u16 start = __ackvec_idx_add(av->av_buf_head, 1),
+	    len	  = DCCPAV_MAX_ACKVEC_LEN - start;
+
+	/* check for buffer wrap-around */
+	if (num > len) {
+		memset(av->av_buf + start, DCCPAV_NOT_RECEIVED, len);
+		start = 0;
+		num  -= len;
+	}
+	if (num)
+		memset(av->av_buf + start, DCCPAV_NOT_RECEIVED, num);
 }
 
-/*
- * Implements the RFC 4340, Appendix A
+/**
+ * dccp_ackvec_add_new  -  Record one or more new entries in Ack Vector buffer
+ * @av:		 container of buffer to update (can be empty or non-empty)
+ * @num_packets: number of packets to register (must be >= 1)
+ * @seqno:	 sequence number of the first packet in @num_packets
+ * @state:	 state in which packet carrying @seqno was received
  */
-int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
-		    const u64 ackno, const u8 state)
+static void dccp_ackvec_add_new(struct dccp_ackvec *av, u32 num_packets,
+				u64 seqno, enum dccp_ackvec_states state)
 {
-	/*
-	 * Check at the right places if the buffer is full, if it is, tell the
-	 * caller to start dropping packets till the HC-Sender acks our ACK
-	 * vectors, when we will free up space in av_buf.
-	 *
-	 * We may well decide to do buffer compression, etc, but for now lets
-	 * just drop.
-	 *
-	 * From Appendix A.1.1 (`New Packets'):
-	 *
-	 *	Of course, the circular buffer may overflow, either when the
-	 *	HC-Sender is sending data at a very high rate, when the
-	 *	HC-Receiver's acknowledgements are not reaching the HC-Sender,
-	 *	or when the HC-Sender is forgetting to acknowledge those acks
-	 *	(so the HC-Receiver is unable to clean up old state). In this
-	 *	case, the HC-Receiver should either compress the buffer (by
-	 *	increasing run lengths when possible), transfer its state to
-	 *	a larger buffer, or, as a last resort, drop all received
-	 *	packets, without processing them whatsoever, until its buffer
-	 *	shrinks again.
-	 */
+	u32 num_cells = num_packets;
 
-	/* See if this is the first ackno being inserted */
-	if (av->av_vec_len == 0) {
-		av->av_buf[av->av_buf_head] = state;
-		av->av_vec_len = 1;
-	} else if (after48(ackno, av->av_buf_ackno)) {
-		const u64 delta = dccp_delta_seqno(av->av_buf_ackno, ackno);
+	if (num_packets > DCCPAV_BURST_THRESH) {
+		u32 lost_packets = num_packets - 1;
 
+		DCCP_WARN("Warning: large burst loss (%u)\n", lost_packets);
 		/*
-		 * Look if the state of this packet is the same as the
-		 * previous ackno and if so if we can bump the head len.
+		 * We received 1 packet and have a loss of size "num_packets-1"
+		 * which we squeeze into num_cells-1 rather than reserving an
+		 * entire byte for each lost packet.
+		 * The reason is that the vector grows in O(burst_length); when
+		 * it grows too large there will no room left for the payload.
+		 * This is a trade-off: if a few packets out of the burst show
+		 * up later, their state will not be changed; it is simply too
+		 * costly to reshuffle/reallocate/copy the buffer each time.
+		 * Should such problems persist, we will need to switch to a
+		 * different underlying data structure.
 		 */
-		if (delta == 1 &&
-		    dccp_ackvec_state(av, av->av_buf_head) == state &&
-		    dccp_ackvec_len(av, av->av_buf_head) < DCCP_ACKVEC_LEN_MASK)
-			av->av_buf[av->av_buf_head]++;
-		else if (dccp_ackvec_set_buf_head_state(av, delta, state))
-			return -ENOBUFS;
-	} else {
-		/*
-		 * A.1.2.  Old Packets
-		 *
-		 *	When a packet with Sequence Number S <= buf_ackno
-		 *	arrives, the HC-Receiver will scan the table for
-		 *	the byte corresponding to S. (Indexing structures
-		 *	could reduce the complexity of this scan.)
-		 */
-		u64 delta = dccp_delta_seqno(ackno, av->av_buf_ackno);
-		u32 index = av->av_buf_head;
+		for (num_packets = num_cells = 1; lost_packets; ++num_cells) {
+			u8 len = min(lost_packets, (u32)DCCPAV_MAX_RUNLEN);
 
-		while (1) {
-			const u8 len = dccp_ackvec_len(av, index);
-			const u8 av_state = dccp_ackvec_state(av, index);
-			/*
-			 * valid packets not yet in av_buf have a reserved
-			 * entry, with a len equal to 0.
-			 */
-			if (av_state == DCCP_ACKVEC_STATE_NOT_RECEIVED &&
-			    len == 0 && delta == 0) { /* Found our
-							 reserved seat! */
-				dccp_pr_debug("Found %llu reserved seat!\n",
-					      (unsigned long long)ackno);
-				av->av_buf[index] = state;
-				goto out;
-			}
-			/* len == 0 means one packet */
-			if (delta < len + 1)
-				goto out_duplicate;
-
-			delta -= len + 1;
-			if (++index == DCCP_MAX_ACKVEC_LEN)
-				index = 0;
+			av->av_buf_head = __ackvec_idx_sub(av->av_buf_head, 1);
+			av->av_buf[av->av_buf_head] = DCCPAV_NOT_RECEIVED | len;
+
+			lost_packets -= len;
 		}
 	}
 
-	av->av_buf_ackno = ackno;
-	av->av_time = ktime_get_real();
-out:
-	return 0;
+	if (num_cells + dccp_ackvec_buflen(av) >= DCCPAV_MAX_ACKVEC_LEN) {
+		DCCP_CRIT("Ack Vector buffer overflow: dropping old entries\n");
+		av->av_overflow = true;
+	}
+
+	av->av_buf_head = __ackvec_idx_sub(av->av_buf_head, num_packets);
+	if (av->av_overflow)
+		av->av_buf_tail = av->av_buf_head;
 
-out_duplicate:
-	/* Duplicate packet */
-	dccp_pr_debug("Received a dup or already considered lost "
-		      "packet: %llu\n", (unsigned long long)ackno);
-	return -EILSEQ;
+	av->av_buf[av->av_buf_head] = state;
+	av->av_buf_ackno	    = seqno;
+
+	if (num_packets > 1)
+		dccp_ackvec_reserve_seats(av, num_packets - 1);
 }
 
-static void dccp_ackvec_throw_record(struct dccp_ackvec *av,
-				     struct dccp_ackvec_record *avr)
+/**
+ * dccp_ackvec_input  -  Register incoming packet in the buffer
+ */
+void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb)
 {
-	struct dccp_ackvec_record *next;
+	u64 seqno = DCCP_SKB_CB(skb)->dccpd_seq;
+	enum dccp_ackvec_states state = DCCPAV_RECEIVED;
 
-	/* sort out vector length */
-	if (av->av_buf_head <= avr->avr_ack_ptr)
-		av->av_vec_len = avr->avr_ack_ptr - av->av_buf_head;
-	else
-		av->av_vec_len = DCCP_MAX_ACKVEC_LEN - 1 -
-				 av->av_buf_head + avr->avr_ack_ptr;
+	if (dccp_ackvec_is_empty(av)) {
+		dccp_ackvec_add_new(av, 1, seqno, state);
+		av->av_tail_ackno = seqno;
 
-	/* free records */
-	list_for_each_entry_safe_from(avr, next, &av->av_records, avr_node) {
-		list_del_init(&avr->avr_node);
-		dccp_ackvec_record_delete(avr);
-	}
-}
+	} else {
+		s64 num_packets = dccp_delta_seqno(av->av_buf_ackno, seqno);
+		u8 *current_head = av->av_buf + av->av_buf_head;
 
-void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk,
-				 const u64 ackno)
-{
-	struct dccp_ackvec_record *avr;
+		if (num_packets == 1 &&
+		    dccp_ackvec_state(current_head) == state &&
+		    dccp_ackvec_runlen(current_head) < DCCPAV_MAX_RUNLEN) {
 
-	/*
-	 * If we traverse backwards, it should be faster when we have large
-	 * windows. We will be receiving ACKs for stuff we sent a while back
-	 * -sorbo.
-	 */
-	list_for_each_entry_reverse(avr, &av->av_records, avr_node) {
-		if (ackno == avr->avr_ack_seqno) {
-			dccp_pr_debug("%s ACK packet 0, len=%d, ack_seqno=%llu, "
-				      "ack_ackno=%llu, ACKED!\n",
-				      dccp_role(sk), 1,
-				      (unsigned long long)avr->avr_ack_seqno,
-				      (unsigned long long)avr->avr_ack_ackno);
-			dccp_ackvec_throw_record(av, avr);
-			break;
-		} else if (avr->avr_ack_seqno > ackno)
-			break; /* old news */
+			*current_head   += 1;
+			av->av_buf_ackno = seqno;
+
+		} else if (num_packets > 0) {
+			dccp_ackvec_add_new(av, num_packets, seqno, state);
+		} else {
+			dccp_ackvec_update_old(av, num_packets, seqno, state);
+		}
 	}
 }
 
-static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
-					    struct sock *sk, u64 *ackno,
-					    const unsigned char len,
-					    const unsigned char *vector)
+/**
+ * dccp_ackvec_clear_state  -  Perform house-keeping / garbage-collection
+ * This routine is called when the peer acknowledges the receipt of Ack Vectors
+ * up to and including @ackno. While based on on section A.3 of RFC 4340, here
+ * are additional precautions to prevent corrupted buffer state. In particular,
+ * we use tail_ackno to identify outdated records; it always marks the earliest
+ * packet of group (2) in 11.4.2.
+ */
+void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno)
 {
-	unsigned char i;
-	struct dccp_ackvec_record *avr;
+	struct dccp_ackvec_record *avr, *next;
+	u8 runlen_now, eff_runlen;
+	s64 delta;
 
-	/* Check if we actually sent an ACK vector */
-	if (list_empty(&av->av_records))
+	avr = dccp_ackvec_lookup(&av->av_records, ackno);
+	if (avr == NULL)
 		return;
+	/*
+	 * Deal with outdated acknowledgments: this arises when e.g. there are
+	 * several old records and the acks from the peer come in slowly. In
+	 * that case we may still have records that pre-date tail_ackno.
+	 */
+	delta = dccp_delta_seqno(av->av_tail_ackno, avr->avr_ack_ackno);
+	if (delta < 0)
+		goto free_records;
+	/*
+	 * Deal with overlapping Ack Vectors: don't subtract more than the
+	 * number of packets between tail_ackno and ack_ackno.
+	 */
+	eff_runlen = delta < avr->avr_ack_runlen ? delta : avr->avr_ack_runlen;
 
-	i = len;
+	runlen_now = dccp_ackvec_runlen(av->av_buf + avr->avr_ack_ptr);
 	/*
-	 * XXX
-	 * I think it might be more efficient to work backwards. See comment on
-	 * rcv_ackno. -sorbo.
+	 * The run length of Ack Vector cells does not decrease over time. If
+	 * the run length is the same as at the time the Ack Vector was sent, we
+	 * free the ack_ptr cell. That cell can however not be freed if the run
+	 * length has increased: in this case we need to move the tail pointer
+	 * backwards (towards higher indices), to its next-oldest neighbour.
 	 */
-	avr = list_entry(av->av_records.next, struct dccp_ackvec_record, avr_node);
-	while (i--) {
-		const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
-		u64 ackno_end_rl;
+	if (runlen_now > eff_runlen) {
 
-		dccp_set_seqno(&ackno_end_rl, *ackno - rl);
+		av->av_buf[avr->avr_ack_ptr] -= eff_runlen + 1;
+		av->av_buf_tail = __ackvec_idx_add(avr->avr_ack_ptr, 1);
 
+		/* This move may not have cleared the overflow flag. */
+		if (av->av_overflow)
+			av->av_overflow = (av->av_buf_head == av->av_buf_tail);
+	} else {
+		av->av_buf_tail	= avr->avr_ack_ptr;
 		/*
-		 * If our AVR sequence number is greater than the ack, go
-		 * forward in the AVR list until it is not so.
+		 * We have made sure that avr points to a valid cell within the
+		 * buffer. This cell is either older than head, or equals head
+		 * (empty buffer): in both cases we no longer have any overflow.
 		 */
-		list_for_each_entry_from(avr, &av->av_records, avr_node) {
-			if (!after48(avr->avr_ack_seqno, *ackno))
-				goto found;
-		}
-		/* End of the av_records list, not found, exit */
-		break;
-found:
-		if (between48(avr->avr_ack_seqno, ackno_end_rl, *ackno)) {
-			const u8 state = *vector & DCCP_ACKVEC_STATE_MASK;
-			if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) {
-				dccp_pr_debug("%s ACK vector 0, len=%d, "
-					      "ack_seqno=%llu, ack_ackno=%llu, "
-					      "ACKED!\n",
-					      dccp_role(sk), len,
-					      (unsigned long long)
-					      avr->avr_ack_seqno,
-					      (unsigned long long)
-					      avr->avr_ack_ackno);
-				dccp_ackvec_throw_record(av, avr);
-				break;
-			}
-			/*
-			 * If it wasn't received, continue scanning... we might
-			 * find another one.
-			 */
-		}
+		av->av_overflow	= 0;
+	}
 
-		dccp_set_seqno(ackno, ackno_end_rl - 1);
-		++vector;
+	/*
+	 * The peer has acknowledged up to and including ack_ackno. Hence the
+	 * first packet in group (2) of 11.4.2 is the successor of ack_ackno.
+	 */
+	av->av_tail_ackno = ADD48(avr->avr_ack_ackno, 1);
+
+free_records:
+	list_for_each_entry_safe_from(avr, next, &av->av_records, avr_node) {
+		list_del(&avr->avr_node);
+		kmem_cache_free(dccp_ackvec_record_slab, avr);
 	}
 }
 
-int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
-		      u64 *ackno, const u8 opt, const u8 *value, const u8 len)
+/*
+ *	Routines to keep track of Ack Vectors received in an skb
+ */
+int dccp_ackvec_parsed_add(struct list_head *head, u8 *vec, u8 len, u8 nonce)
 {
-	if (len > DCCP_SINGLE_OPT_MAXLEN)
-		return -1;
+	struct dccp_ackvec_parsed *new = kmalloc(sizeof(*new), GFP_ATOMIC);
+
+	if (new == NULL)
+		return -ENOBUFS;
+	new->vec   = vec;
+	new->len   = len;
+	new->nonce = nonce;
 
-	/* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */
-	dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk,
-					ackno, len, value);
+	list_add_tail(&new->node, head);
 	return 0;
 }
+EXPORT_SYMBOL_GPL(dccp_ackvec_parsed_add);
+
+void dccp_ackvec_parsed_cleanup(struct list_head *parsed_chunks)
+{
+	struct dccp_ackvec_parsed *cur, *next;
+
+	list_for_each_entry_safe(cur, next, parsed_chunks, node)
+		kfree(cur);
+	INIT_LIST_HEAD(parsed_chunks);
+}
+EXPORT_SYMBOL_GPL(dccp_ackvec_parsed_cleanup);
 
 int __init dccp_ackvec_init(void)
 {
@@ -448,10 +379,9 @@ int __init dccp_ackvec_init(void)
 	if (dccp_ackvec_slab == NULL)
 		goto out_err;
 
-	dccp_ackvec_record_slab =
-			kmem_cache_create("dccp_ackvec_record",
-					  sizeof(struct dccp_ackvec_record),
-					  0, SLAB_HWCACHE_ALIGN, NULL);
+	dccp_ackvec_record_slab = kmem_cache_create("dccp_ackvec_record",
+					     sizeof(struct dccp_ackvec_record),
+					     0, SLAB_HWCACHE_ALIGN, NULL);
 	if (dccp_ackvec_record_slab == NULL)
 		goto out_destroy_slab;
 
diff --git a/net/dccp/ackvec.h b/net/dccp/ackvec.h
index 7ea557b7c6b..e2ab0627a5f 100644
--- a/net/dccp/ackvec.h
+++ b/net/dccp/ackvec.h
@@ -3,9 +3,9 @@
 /*
  *  net/dccp/ackvec.h
  *
- *  An implementation of the DCCP protocol
+ *  An implementation of Ack Vectors for the DCCP protocol
+ *  Copyright (c) 2007 University of Aberdeen, Scotland, UK
  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@mandriva.com>
- *
  *	This program is free software; you can redistribute it and/or modify it
  *	under the terms of the GNU General Public License version 2 as
  *	published by the Free Software Foundation.
@@ -13,99 +13,124 @@
 
 #include <linux/dccp.h>
 #include <linux/compiler.h>
-#include <linux/ktime.h>
 #include <linux/list.h>
 #include <linux/types.h>
 
-/* We can spread an ack vector across multiple options */
-#define DCCP_MAX_ACKVEC_LEN (DCCP_SINGLE_OPT_MAXLEN * 2)
+/*
+ * Ack Vector buffer space is static, in multiples of %DCCP_SINGLE_OPT_MAXLEN,
+ * the maximum size of a single Ack Vector. Setting %DCCPAV_NUM_ACKVECS to 1
+ * will be sufficient for most cases of low Ack Ratios, using a value of 2 gives
+ * more headroom if Ack Ratio is higher or when the sender acknowledges slowly.
+ * The maximum value is bounded by the u16 types for indices and functions.
+ */
+#define DCCPAV_NUM_ACKVECS	2
+#define DCCPAV_MAX_ACKVEC_LEN	(DCCP_SINGLE_OPT_MAXLEN * DCCPAV_NUM_ACKVECS)
 
 /* Estimated minimum average Ack Vector length - used for updating MPS */
 #define DCCPAV_MIN_OPTLEN	16
 
-#define DCCP_ACKVEC_STATE_RECEIVED	0
-#define DCCP_ACKVEC_STATE_ECN_MARKED	(1 << 6)
-#define DCCP_ACKVEC_STATE_NOT_RECEIVED	(3 << 6)
+/* Threshold for coping with large bursts of losses */
+#define DCCPAV_BURST_THRESH	(DCCPAV_MAX_ACKVEC_LEN / 8)
 
-#define DCCP_ACKVEC_STATE_MASK		0xC0 /* 11000000 */
-#define DCCP_ACKVEC_LEN_MASK		0x3F /* 00111111 */
+enum dccp_ackvec_states {
+	DCCPAV_RECEIVED =	0x00,
+	DCCPAV_ECN_MARKED =	0x40,
+	DCCPAV_RESERVED =	0x80,
+	DCCPAV_NOT_RECEIVED =	0xC0
+};
+#define DCCPAV_MAX_RUNLEN	0x3F
 
-/** struct dccp_ackvec - ack vector
- *
- * This data structure is the one defined in RFC 4340, Appendix A.
- *
- * @av_buf_head - circular buffer head
- * @av_buf_tail - circular buffer tail
- * @av_buf_ackno - ack # of the most recent packet acknowledgeable in the
- *		       buffer (i.e. %av_buf_head)
- * @av_buf_nonce - the one-bit sum of the ECN Nonces on all packets acked
- * 		       by the buffer with State 0
- *
- * Additionally, the HC-Receiver must keep some information about the
- * Ack Vectors it has recently sent. For each packet sent carrying an
- * Ack Vector, it remembers four variables:
+static inline u8 dccp_ackvec_runlen(const u8 *cell)
+{
+	return *cell & DCCPAV_MAX_RUNLEN;
+}
+
+static inline u8 dccp_ackvec_state(const u8 *cell)
+{
+	return *cell & ~DCCPAV_MAX_RUNLEN;
+}
+
+/** struct dccp_ackvec - Ack Vector main data structure
  *
- * @av_records - list of dccp_ackvec_record
- * @av_ack_nonce - the one-bit sum of the ECN Nonces for all State 0.
+ * This implements a fixed-size circular buffer within an array and is largely
+ * based on Appendix A of RFC 4340.
  *
- * @av_time - the time in usecs
- * @av_buf - circular buffer of acknowledgeable packets
+ * @av_buf:	   circular buffer storage area
+ * @av_buf_head:   head index; begin of live portion in @av_buf
+ * @av_buf_tail:   tail index; first index _after_ the live portion in @av_buf
+ * @av_buf_ackno:  highest seqno of acknowledgeable packet recorded in @av_buf
+ * @av_tail_ackno: lowest  seqno of acknowledgeable packet recorded in @av_buf
+ * @av_buf_nonce:  ECN nonce sums, each covering subsequent segments of up to
+ *		   %DCCP_SINGLE_OPT_MAXLEN cells in the live portion of @av_buf
+ * @av_overflow:   if 1 then buf_head == buf_tail indicates buffer wraparound
+ * @av_records:	   list of %dccp_ackvec_record (Ack Vectors sent previously)
  */
 struct dccp_ackvec {
-	u64			av_buf_ackno;
-	struct list_head	av_records;
-	ktime_t			av_time;
+	u8			av_buf[DCCPAV_MAX_ACKVEC_LEN];
 	u16			av_buf_head;
-	u16			av_vec_len;
-	u8			av_buf_nonce;
-	u8			av_ack_nonce;
-	u8			av_buf[DCCP_MAX_ACKVEC_LEN];
+	u16			av_buf_tail;
+	u64			av_buf_ackno:48;
+	u64			av_tail_ackno:48;
+	bool			av_buf_nonce[DCCPAV_NUM_ACKVECS];
+	u8			av_overflow:1;
+	struct list_head	av_records;
 };
 
-/** struct dccp_ackvec_record - ack vector record
+/** struct dccp_ackvec_record - Records information about sent Ack Vectors
  *
- * ACK vector record as defined in Appendix A of spec.
+ * These list entries define the additional information which the HC-Receiver
+ * keeps about recently-sent Ack Vectors; again refer to RFC 4340, Appendix A.
  *
- * The list is sorted by avr_ack_seqno
+ * @avr_node:	    the list node in @av_records
+ * @avr_ack_seqno:  sequence number of the packet the Ack Vector was sent on
+ * @avr_ack_ackno:  the Ack number that this record/Ack Vector refers to
+ * @avr_ack_ptr:    pointer into @av_buf where this record starts
+ * @avr_ack_runlen: run length of @avr_ack_ptr at the time of sending
+ * @avr_ack_nonce:  the sum of @av_buf_nonce's at the time this record was sent
  *
- * @avr_node - node in av_records
- * @avr_ack_seqno - sequence number of the packet this record was sent on
- * @avr_ack_ackno - sequence number being acknowledged
- * @avr_ack_ptr - pointer into av_buf where this record starts
- * @avr_ack_nonce - av_ack_nonce at the time this record was sent
- * @avr_sent_len - lenght of the record in av_buf
+ * The list as a whole is sorted in descending order by @avr_ack_seqno.
  */
 struct dccp_ackvec_record {
 	struct list_head avr_node;
-	u64		 avr_ack_seqno;
-	u64		 avr_ack_ackno;
+	u64		 avr_ack_seqno:48;
+	u64		 avr_ack_ackno:48;
 	u16		 avr_ack_ptr;
-	u16		 avr_sent_len;
-	u8		 avr_ack_nonce;
+	u8		 avr_ack_runlen;
+	u8		 avr_ack_nonce:1;
 };
 
-struct sock;
-struct sk_buff;
-
 extern int dccp_ackvec_init(void);
 extern void dccp_ackvec_exit(void);
 
 extern struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority);
 extern void dccp_ackvec_free(struct dccp_ackvec *av);
 
-extern int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
-			   const u64 ackno, const u8 state);
-
-extern void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
-					struct sock *sk, const u64 ackno);
-extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
-			     u64 *ackno, const u8 opt,
-			     const u8 *value, const u8 len);
+extern void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb);
+extern int  dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum);
+extern void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno);
+extern u16  dccp_ackvec_buflen(const struct dccp_ackvec *av);
 
-extern int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb);
-
-static inline int dccp_ackvec_pending(const struct dccp_ackvec *av)
+static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av)
 {
-	return av->av_vec_len;
+	return av->av_overflow == 0 && av->av_buf_head == av->av_buf_tail;
 }
+
+/**
+ * struct dccp_ackvec_parsed  -  Record offsets of Ack Vectors in skb
+ * @vec:	start of vector (offset into skb)
+ * @len:	length of @vec
+ * @nonce:	whether @vec had an ECN nonce of 0 or 1
+ * @node:	FIFO - arranged in descending order of ack_ackno
+ * This structure is used by CCIDs to access Ack Vectors in a received skb.
+ */
+struct dccp_ackvec_parsed {
+	u8		 *vec,
+			 len,
+			 nonce:1;
+	struct list_head node;
+};
+
+extern int dccp_ackvec_parsed_add(struct list_head *head,
+				  u8 *vec, u8 len, u8 nonce);
+extern void dccp_ackvec_parsed_cleanup(struct list_head *parsed_chunks);
 #endif /* _ACKVEC_H */
diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
index 6576eae9e77..e96d5e81003 100644
--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -246,68 +246,6 @@ static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len)
 #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;
-}
-
 /**
  * ccid2_rtt_estimator - Sample RTT and compute RTO using RFC2988 algorithm
  * This code is almost identical with TCP's tcp_rtt_estimator(), since
@@ -432,16 +370,28 @@ static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
 		ccid2_change_l_ack_ratio(sk, hc->tx_cwnd);
 }
 
+static int ccid2_hc_tx_parse_options(struct sock *sk, u8 packet_type,
+				     u8 option, u8 *optval, u8 optlen)
+{
+	struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
+
+	switch (option) {
+	case DCCPO_ACK_VECTOR_0:
+	case DCCPO_ACK_VECTOR_1:
+		return dccp_ackvec_parsed_add(&hc->tx_av_chunks, optval, optlen,
+					      option - DCCPO_ACK_VECTOR_0);
+	}
+	return 0;
+}
+
 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 *hc = ccid2_hc_tx_sk(sk);
 	const bool sender_was_blocked = ccid2_cwnd_network_limited(hc);
+	struct dccp_ackvec_parsed *avp;
 	u64 ackno, seqno;
 	struct ccid2_seq *seqp;
-	unsigned char *vector;
-	unsigned char veclen;
-	int offset = 0;
 	int done = 0;
 	unsigned int maxincr = 0;
 
@@ -475,17 +425,12 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 	}
 
 	/* check forward path congestion */
-	/* still didn't send out new data packets */
-	if (hc->tx_seqh == hc->tx_seqt)
+	if (dccp_packet_without_ack(skb))
 		return;
 
-	switch (DCCP_SKB_CB(skb)->dccpd_type) {
-	case DCCP_PKT_ACK:
-	case DCCP_PKT_DATAACK:
-		break;
-	default:
-		return;
-	}
+	/* still didn't send out new data packets */
+	if (hc->tx_seqh == hc->tx_seqt)
+		goto done;
 
 	ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
 	if (after48(ackno, hc->tx_high_ack))
@@ -509,16 +454,16 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 		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) {
+	list_for_each_entry(avp, &hc->tx_av_chunks, node) {
 		/* go through this ack vector */
-		while (veclen--) {
-			const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
-			u64 ackno_end_rl = SUB48(ackno, rl);
+		for (; avp->len--; avp->vec++) {
+			u64 ackno_end_rl = SUB48(ackno,
+						 dccp_ackvec_runlen(avp->vec));
 
-			ccid2_pr_debug("ackvec start:%llu end:%llu\n",
+			ccid2_pr_debug("ackvec %llu |%u,%u|\n",
 				       (unsigned long long)ackno,
-				       (unsigned long long)ackno_end_rl);
+				       dccp_ackvec_state(avp->vec) >> 6,
+				       dccp_ackvec_runlen(avp->vec));
 			/* if the seqno we are analyzing is larger than the
 			 * current ackno, then move towards the tail of our
 			 * seqnos.
@@ -537,17 +482,15 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 			 * run length
 			 */
 			while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) {
-				const u8 state = *vector &
-						 DCCP_ACKVEC_STATE_MASK;
+				const u8 state = dccp_ackvec_state(avp->vec);
 
 				/* new packet received or marked */
-				if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED &&
+				if (state != DCCPAV_NOT_RECEIVED &&
 				    !seqp->ccid2s_acked) {
-					if (state ==
-					    DCCP_ACKVEC_STATE_ECN_MARKED) {
+					if (state == DCCPAV_ECN_MARKED)
 						ccid2_congestion_event(sk,
 								       seqp);
-					} else
+					else
 						ccid2_new_ack(sk, seqp,
 							      &maxincr);
 
@@ -566,7 +509,6 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 				break;
 
 			ackno = SUB48(ackno_end_rl, 1);
-			vector++;
 		}
 		if (done)
 			break;
@@ -634,10 +576,11 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 		sk_stop_timer(sk, &hc->tx_rtotimer);
 	else
 		sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto);
-
+done:
 	/* check if incoming Acks allow pending packets to be sent */
 	if (sender_was_blocked && !ccid2_cwnd_network_limited(hc))
 		tasklet_schedule(&dccp_sk(sk)->dccps_xmitlet);
+	dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks);
 }
 
 static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
@@ -666,6 +609,7 @@ static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
 	hc->tx_last_cong = ccid2_time_stamp;
 	setup_timer(&hc->tx_rtotimer, ccid2_hc_tx_rto_expire,
 			(unsigned long)sk);
+	INIT_LIST_HEAD(&hc->tx_av_chunks);
 	return 0;
 }
 
@@ -699,16 +643,17 @@ static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
 }
 
 struct ccid_operations ccid2_ops = {
-	.ccid_id		= DCCPC_CCID2,
-	.ccid_name		= "TCP-like",
-	.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,
+	.ccid_id		  = DCCPC_CCID2,
+	.ccid_name		  = "TCP-like",
+	.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_parse_options = ccid2_hc_tx_parse_options,
+	.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
diff --git a/net/dccp/ccids/ccid2.h b/net/dccp/ccids/ccid2.h
index 25cb6b216ed..e9985dafc2c 100644
--- a/net/dccp/ccids/ccid2.h
+++ b/net/dccp/ccids/ccid2.h
@@ -55,6 +55,7 @@ struct ccid2_seq {
  * @tx_rtt_seq:		     to decay RTTVAR at most once per flight
  * @tx_rpseq:		     last consecutive seqno
  * @tx_rpdupack:	     dupacks since rpseq
+ * @tx_av_chunks:	     list of Ack Vectors received on current skb
  */
 struct ccid2_hc_tx_sock {
 	u32			tx_cwnd;
@@ -79,6 +80,7 @@ struct ccid2_hc_tx_sock {
 	int			tx_rpdupack;
 	u32			tx_last_cong;
 	u64			tx_high_ack;
+	struct list_head	tx_av_chunks;
 };
 
 static inline bool ccid2_cwnd_network_limited(struct ccid2_hc_tx_sock *hc)
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index a8ed459508b..45087052d89 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -93,9 +93,6 @@ extern void dccp_time_wait(struct sock *sk, int state, int timeo);
 #define DCCP_FALLBACK_RTT	(USEC_PER_SEC / 5)
 #define DCCP_SANE_RTT_MAX	(3 * USEC_PER_SEC)
 
-/* Maximal interval between probes for local resources.  */
-#define DCCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ / 2U))
-
 /* sysctl variables for DCCP */
 extern int  sysctl_dccp_request_retries;
 extern int  sysctl_dccp_retries1;
@@ -203,12 +200,7 @@ struct dccp_mib {
 DECLARE_SNMP_STAT(struct dccp_mib, dccp_statistics);
 #define DCCP_INC_STATS(field)	    SNMP_INC_STATS(dccp_statistics, field)
 #define DCCP_INC_STATS_BH(field)    SNMP_INC_STATS_BH(dccp_statistics, field)
-#define DCCP_INC_STATS_USER(field)  SNMP_INC_STATS_USER(dccp_statistics, field)
 #define DCCP_DEC_STATS(field)	    SNMP_DEC_STATS(dccp_statistics, field)
-#define DCCP_ADD_STATS_BH(field, val) \
-			SNMP_ADD_STATS_BH(dccp_statistics, field, val)
-#define DCCP_ADD_STATS_USER(field, val)	\
-			SNMP_ADD_STATS_USER(dccp_statistics, field, val)
 
 /*
  * 	Checksumming routines
@@ -243,6 +235,19 @@ extern void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 extern void dccp_send_sync(struct sock *sk, const u64 seq,
 			   const enum dccp_pkt_type pkt_type);
 
+/*
+ * TX Packet Dequeueing Interface
+ */
+extern void		dccp_qpolicy_push(struct sock *sk, struct sk_buff *skb);
+extern bool		dccp_qpolicy_full(struct sock *sk);
+extern void		dccp_qpolicy_drop(struct sock *sk, struct sk_buff *skb);
+extern struct sk_buff	*dccp_qpolicy_top(struct sock *sk);
+extern struct sk_buff	*dccp_qpolicy_pop(struct sock *sk);
+extern bool		dccp_qpolicy_param_ok(struct sock *sk, __be32 param);
+
+/*
+ * TX Packet Output and TX Timers
+ */
 extern void   dccp_write_xmit(struct sock *sk);
 extern void   dccp_write_space(struct sock *sk);
 extern void   dccp_flush_write_queue(struct sock *sk, long *time_budget);
@@ -457,12 +462,15 @@ static inline void dccp_update_gss(struct sock *sk, u64 seq)
 	dp->dccps_awh = dp->dccps_gss;
 }
 
+static inline int dccp_ackvec_pending(const struct sock *sk)
+{
+	return dccp_sk(sk)->dccps_hc_rx_ackvec != NULL &&
+	       !dccp_ackvec_is_empty(dccp_sk(sk)->dccps_hc_rx_ackvec);
+}
+
 static inline int dccp_ack_pending(const struct sock *sk)
 {
-	const struct dccp_sock *dp = dccp_sk(sk);
-	return (dp->dccps_hc_rx_ackvec != NULL &&
-		dccp_ackvec_pending(dp->dccps_hc_rx_ackvec)) ||
-	       inet_csk_ack_scheduled(sk);
+	return dccp_ackvec_pending(sk) || inet_csk_ack_scheduled(sk);
 }
 
 extern int  dccp_feat_finalise_settings(struct dccp_sock *dp);
diff --git a/net/dccp/input.c b/net/dccp/input.c
index e424a09e83f..15af247ea00 100644
--- a/net/dccp/input.c
+++ b/net/dccp/input.c
@@ -160,13 +160,15 @@ static void dccp_rcv_reset(struct sock *sk, struct sk_buff *skb)
 	dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
 }
 
-static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
+static void dccp_handle_ackvec_processing(struct sock *sk, struct sk_buff *skb)
 {
-	struct dccp_sock *dp = dccp_sk(sk);
+	struct dccp_ackvec *av = dccp_sk(sk)->dccps_hc_rx_ackvec;
 
-	if (dp->dccps_hc_rx_ackvec != NULL)
-		dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,
-					    DCCP_SKB_CB(skb)->dccpd_ack_seq);
+	if (av == NULL)
+		return;
+	if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
+		dccp_ackvec_clear_state(av, DCCP_SKB_CB(skb)->dccpd_ack_seq);
+	dccp_ackvec_input(av, skb);
 }
 
 static void dccp_deliver_input_to_ccids(struct sock *sk, struct sk_buff *skb)
@@ -366,22 +368,13 @@ discard:
 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 			 const struct dccp_hdr *dh, const unsigned len)
 {
-	struct dccp_sock *dp = dccp_sk(sk);
-
 	if (dccp_check_seqno(sk, skb))
 		goto discard;
 
 	if (dccp_parse_options(sk, NULL, skb))
 		return 1;
 
-	if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
-		dccp_event_ack_recv(sk, skb);
-
-	if (dp->dccps_hc_rx_ackvec != NULL &&
-	    dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
-			    DCCP_SKB_CB(skb)->dccpd_seq,
-			    DCCP_ACKVEC_STATE_RECEIVED))
-		goto discard;
+	dccp_handle_ackvec_processing(sk, skb);
 	dccp_deliver_input_to_ccids(sk, skb);
 
 	return __dccp_rcv_established(sk, skb, dh, len);
@@ -633,15 +626,7 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 		if (dccp_parse_options(sk, NULL, skb))
 			return 1;
 
-		if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
-			dccp_event_ack_recv(sk, skb);
-
-		if (dp->dccps_hc_rx_ackvec != NULL &&
-		    dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
-				    DCCP_SKB_CB(skb)->dccpd_seq,
-				    DCCP_ACKVEC_STATE_RECEIVED))
-			goto discard;
-
+		dccp_handle_ackvec_processing(sk, skb);
 		dccp_deliver_input_to_ccids(sk, skb);
 	}
 
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 3f69ea11482..45a434f9416 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -462,15 +462,12 @@ static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
 {
 	struct rtable *rt;
 	struct flowi fl = { .oif = skb_rtable(skb)->rt_iif,
-			    .nl_u = { .ip4_u =
-				      { .daddr = ip_hdr(skb)->saddr,
-					.saddr = ip_hdr(skb)->daddr,
-					.tos = RT_CONN_FLAGS(sk) } },
+			    .fl4_dst = ip_hdr(skb)->saddr,
+			    .fl4_src = ip_hdr(skb)->daddr,
+			    .fl4_tos = RT_CONN_FLAGS(sk),
 			    .proto = sk->sk_protocol,
-			    .uli_u = { .ports =
-				       { .sport = dccp_hdr(skb)->dccph_dport,
-					 .dport = dccp_hdr(skb)->dccph_sport }
-				     }
+			    .fl_ip_sport = dccp_hdr(skb)->dccph_dport,
+			    .fl_ip_dport = dccp_hdr(skb)->dccph_sport
 			  };
 
 	security_skb_classify_flow(skb, &fl);
diff --git a/net/dccp/options.c b/net/dccp/options.c
index cd306181300..f06ffcfc8d7 100644
--- a/net/dccp/options.c
+++ b/net/dccp/options.c
@@ -54,7 +54,6 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
 	struct dccp_sock *dp = dccp_sk(sk);
 	const struct dccp_hdr *dh = dccp_hdr(skb);
 	const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
-	u64 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
 	unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
 	unsigned char *opt_ptr = options;
 	const unsigned char *opt_end = (unsigned char *)dh +
@@ -129,14 +128,6 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
 			if (rc)
 				goto out_featneg_failed;
 			break;
-		case DCCPO_ACK_VECTOR_0:
-		case DCCPO_ACK_VECTOR_1:
-			if (dccp_packet_without_ack(skb))   /* RFC 4340, 11.4 */
-				break;
-			if (dp->dccps_hc_rx_ackvec != NULL &&
-			    dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
-				goto out_invalid_option;
-			break;
 		case DCCPO_TIMESTAMP:
 			if (len != 4)
 				goto out_invalid_option;
@@ -226,6 +217,16 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
 						     pkt_type, opt, value, len))
 				goto out_invalid_option;
 			break;
+		case DCCPO_ACK_VECTOR_0:
+		case DCCPO_ACK_VECTOR_1:
+			if (dccp_packet_without_ack(skb))   /* RFC 4340, 11.4 */
+				break;
+			/*
+			 * Ack vectors are processed by the TX CCID if it is
+			 * interested. The RX CCID need not parse Ack Vectors,
+			 * since it is only interested in clearing old state.
+			 * Fall through.
+			 */
 		case DCCPO_MIN_TX_CCID_SPECIFIC ... DCCPO_MAX_TX_CCID_SPECIFIC:
 			if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
 						     pkt_type, opt, value, len))
@@ -340,6 +341,7 @@ static inline int dccp_elapsed_time_len(const u32 elapsed_time)
 	return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
 }
 
+/* FIXME: This function is currently not used anywhere */
 int dccp_insert_option_elapsed_time(struct sk_buff *skb, u32 elapsed_time)
 {
 	const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
@@ -424,6 +426,83 @@ static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
 	return 0;
 }
 
+static int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
+{
+	struct dccp_sock *dp = dccp_sk(sk);
+	struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
+	struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
+	const u16 buflen = dccp_ackvec_buflen(av);
+	/* Figure out how many options do we need to represent the ackvec */
+	const u8 nr_opts = DIV_ROUND_UP(buflen, DCCP_SINGLE_OPT_MAXLEN);
+	u16 len = buflen + 2 * nr_opts;
+	u8 i, nonce = 0;
+	const unsigned char *tail, *from;
+	unsigned char *to;
+
+	if (dcb->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) {
+		DCCP_WARN("Lacking space for %u bytes on %s packet\n", len,
+			  dccp_packet_name(dcb->dccpd_type));
+		return -1;
+	}
+	/*
+	 * Since Ack Vectors are variable-length, we can not always predict
+	 * their size. To catch exception cases where the space is running out
+	 * on the skb, a separate Sync is scheduled to carry the Ack Vector.
+	 */
+	if (len > DCCPAV_MIN_OPTLEN &&
+	    len + dcb->dccpd_opt_len + skb->len > dp->dccps_mss_cache) {
+		DCCP_WARN("No space left for Ack Vector (%u) on skb (%u+%u), "
+			  "MPS=%u ==> reduce payload size?\n", len, skb->len,
+			  dcb->dccpd_opt_len, dp->dccps_mss_cache);
+		dp->dccps_sync_scheduled = 1;
+		return 0;
+	}
+	dcb->dccpd_opt_len += len;
+
+	to   = skb_push(skb, len);
+	len  = buflen;
+	from = av->av_buf + av->av_buf_head;
+	tail = av->av_buf + DCCPAV_MAX_ACKVEC_LEN;
+
+	for (i = 0; i < nr_opts; ++i) {
+		int copylen = len;
+
+		if (len > DCCP_SINGLE_OPT_MAXLEN)
+			copylen = DCCP_SINGLE_OPT_MAXLEN;
+
+		/*
+		 * RFC 4340, 12.2: Encode the Nonce Echo for this Ack Vector via
+		 * its type; ack_nonce is the sum of all individual buf_nonce's.
+		 */
+		nonce ^= av->av_buf_nonce[i];
+
+		*to++ = DCCPO_ACK_VECTOR_0 + av->av_buf_nonce[i];
+		*to++ = copylen + 2;
+
+		/* Check if buf_head wraps */
+		if (from + copylen > tail) {
+			const u16 tailsize = tail - from;
+
+			memcpy(to, from, tailsize);
+			to	+= tailsize;
+			len	-= tailsize;
+			copylen	-= tailsize;
+			from	= av->av_buf;
+		}
+
+		memcpy(to, from, copylen);
+		from += copylen;
+		to   += copylen;
+		len  -= copylen;
+	}
+	/*
+	 * Each sent Ack Vector is recorded in the list, as per A.2 of RFC 4340.
+	 */
+	if (dccp_ackvec_update_records(av, dcb->dccpd_seq, nonce))
+		return -ENOBUFS;
+	return 0;
+}
+
 /**
  * dccp_insert_option_mandatory  -  Mandatory option (5.8.2)
  * Note that since we are using skb_push, this function needs to be called
@@ -519,8 +598,7 @@ int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 			if (dccp_insert_option_timestamp(skb))
 				return -1;
 
-		} else if (dp->dccps_hc_rx_ackvec != NULL &&
-			   dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
+		} else if (dccp_ackvec_pending(sk) &&
 			   dccp_insert_option_ackvec(sk, skb)) {
 				return -1;
 		}
diff --git a/net/dccp/output.c b/net/dccp/output.c
index 45b91853f5a..784d3021054 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -242,7 +242,7 @@ static void dccp_xmit_packet(struct sock *sk)
 {
 	int err, len;
 	struct dccp_sock *dp = dccp_sk(sk);
-	struct sk_buff *skb = skb_dequeue(&sk->sk_write_queue);
+	struct sk_buff *skb = dccp_qpolicy_pop(sk);
 
 	if (unlikely(skb == NULL))
 		return;
@@ -283,6 +283,15 @@ static void dccp_xmit_packet(struct sock *sk)
 	 * any local drop will eventually be reported via receiver feedback.
 	 */
 	ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, len);
+
+	/*
+	 * If the CCID needs to transfer additional header options out-of-band
+	 * (e.g. Ack Vectors or feature-negotiation options), it activates this
+	 * flag to schedule a Sync. The Sync will automatically incorporate all
+	 * currently pending header options, thus clearing the backlog.
+	 */
+	if (dp->dccps_sync_scheduled)
+		dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
 }
 
 /**
@@ -336,7 +345,7 @@ void dccp_write_xmit(struct sock *sk)
 	struct dccp_sock *dp = dccp_sk(sk);
 	struct sk_buff *skb;
 
-	while ((skb = skb_peek(&sk->sk_write_queue))) {
+	while ((skb = dccp_qpolicy_top(sk))) {
 		int rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb);
 
 		switch (ccid_packet_dequeue_eval(rc)) {
@@ -350,8 +359,7 @@ void dccp_write_xmit(struct sock *sk)
 			dccp_xmit_packet(sk);
 			break;
 		case CCID_PACKET_ERR:
-			skb_dequeue(&sk->sk_write_queue);
-			kfree_skb(skb);
+			dccp_qpolicy_drop(sk, skb);
 			dccp_pr_debug("packet discarded due to err=%d\n", rc);
 		}
 	}
@@ -636,6 +644,12 @@ void dccp_send_sync(struct sock *sk, const u64 ackno,
 	DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
 	DCCP_SKB_CB(skb)->dccpd_ack_seq = ackno;
 
+	/*
+	 * Clear the flag in case the Sync was scheduled for out-of-band data,
+	 * such as carrying a long Ack Vector.
+	 */
+	dccp_sk(sk)->dccps_sync_scheduled = 0;
+
 	dccp_transmit_skb(sk, skb);
 }
 
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index ef343d53fce..152975d942d 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -185,6 +185,7 @@ int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized)
 	dp->dccps_role		= DCCP_ROLE_UNDEFINED;
 	dp->dccps_service	= DCCP_SERVICE_CODE_IS_ABSENT;
 	dp->dccps_l_ack_ratio	= dp->dccps_r_ack_ratio = 1;
+	dp->dccps_tx_qlen	= sysctl_dccp_tx_qlen;
 
 	dccp_init_xmit_timers(sk);
 
@@ -532,6 +533,20 @@ static int do_dccp_setsockopt(struct sock *sk, int level, int optname,
 	case DCCP_SOCKOPT_RECV_CSCOV:
 		err = dccp_setsockopt_cscov(sk, val, true);
 		break;
+	case DCCP_SOCKOPT_QPOLICY_ID:
+		if (sk->sk_state != DCCP_CLOSED)
+			err = -EISCONN;
+		else if (val < 0 || val >= DCCPQ_POLICY_MAX)
+			err = -EINVAL;
+		else
+			dp->dccps_qpolicy = val;
+		break;
+	case DCCP_SOCKOPT_QPOLICY_TXQLEN:
+		if (val < 0)
+			err = -EINVAL;
+		else
+			dp->dccps_tx_qlen = val;
+		break;
 	default:
 		err = -ENOPROTOOPT;
 		break;
@@ -639,6 +654,12 @@ static int do_dccp_getsockopt(struct sock *sk, int level, int optname,
 	case DCCP_SOCKOPT_RECV_CSCOV:
 		val = dp->dccps_pcrlen;
 		break;
+	case DCCP_SOCKOPT_QPOLICY_ID:
+		val = dp->dccps_qpolicy;
+		break;
+	case DCCP_SOCKOPT_QPOLICY_TXQLEN:
+		val = dp->dccps_tx_qlen;
+		break;
 	case 128 ... 191:
 		return ccid_hc_rx_getsockopt(dp->dccps_hc_rx_ccid, sk, optname,
 					     len, (u32 __user *)optval, optlen);
@@ -681,6 +702,47 @@ int compat_dccp_getsockopt(struct sock *sk, int level, int optname,
 EXPORT_SYMBOL_GPL(compat_dccp_getsockopt);
 #endif
 
+static int dccp_msghdr_parse(struct msghdr *msg, struct sk_buff *skb)
+{
+	struct cmsghdr *cmsg = CMSG_FIRSTHDR(msg);
+
+	/*
+	 * Assign an (opaque) qpolicy priority value to skb->priority.
+	 *
+	 * We are overloading this skb field for use with the qpolicy subystem.
+	 * The skb->priority is normally used for the SO_PRIORITY option, which
+	 * is initialised from sk_priority. Since the assignment of sk_priority
+	 * to skb->priority happens later (on layer 3), we overload this field
+	 * for use with queueing priorities as long as the skb is on layer 4.
+	 * The default priority value (if nothing is set) is 0.
+	 */
+	skb->priority = 0;
+
+	for (; cmsg != NULL; cmsg = CMSG_NXTHDR(msg, cmsg)) {
+
+		if (!CMSG_OK(msg, cmsg))
+			return -EINVAL;
+
+		if (cmsg->cmsg_level != SOL_DCCP)
+			continue;
+
+		if (cmsg->cmsg_type <= DCCP_SCM_QPOLICY_MAX &&
+		    !dccp_qpolicy_param_ok(skb->sk, cmsg->cmsg_type))
+			return -EINVAL;
+
+		switch (cmsg->cmsg_type) {
+		case DCCP_SCM_PRIORITY:
+			if (cmsg->cmsg_len != CMSG_LEN(sizeof(__u32)))
+				return -EINVAL;
+			skb->priority = *(__u32 *)CMSG_DATA(cmsg);
+			break;
+		default:
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+
 int dccp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 		 size_t len)
 {
@@ -696,8 +758,7 @@ int dccp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 
 	lock_sock(sk);
 
-	if (sysctl_dccp_tx_qlen &&
-	    (sk->sk_write_queue.qlen >= sysctl_dccp_tx_qlen)) {
+	if (dccp_qpolicy_full(sk)) {
 		rc = -EAGAIN;
 		goto out_release;
 	}
@@ -725,7 +786,11 @@ int dccp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	if (rc != 0)
 		goto out_discard;
 
-	skb_queue_tail(&sk->sk_write_queue, skb);
+	rc = dccp_msghdr_parse(msg, skb);
+	if (rc != 0)
+		goto out_discard;
+
+	dccp_qpolicy_push(sk, skb);
 	/*
 	 * The xmit_timer is set if the TX CCID is rate-based and will expire
 	 * when congestion control permits to release further packets into the
diff --git a/net/dccp/qpolicy.c b/net/dccp/qpolicy.c
new file mode 100644
index 00000000000..63c30bfa470
--- /dev/null
+++ b/net/dccp/qpolicy.c
@@ -0,0 +1,137 @@
+/*
+ *  net/dccp/qpolicy.c
+ *
+ *  Policy-based packet dequeueing interface for DCCP.
+ *
+ *  Copyright (c) 2008 Tomasz Grobelny <tomasz@grobelny.oswiecenia.net>
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License v2
+ *  as published by the Free Software Foundation.
+ */
+#include "dccp.h"
+
+/*
+ *	Simple Dequeueing Policy:
+ *	If tx_qlen is different from 0, enqueue up to tx_qlen elements.
+ */
+static void qpolicy_simple_push(struct sock *sk, struct sk_buff *skb)
+{
+	skb_queue_tail(&sk->sk_write_queue, skb);
+}
+
+static bool qpolicy_simple_full(struct sock *sk)
+{
+	return dccp_sk(sk)->dccps_tx_qlen &&
+	       sk->sk_write_queue.qlen >= dccp_sk(sk)->dccps_tx_qlen;
+}
+
+static struct sk_buff *qpolicy_simple_top(struct sock *sk)
+{
+	return skb_peek(&sk->sk_write_queue);
+}
+
+/*
+ *	Priority-based Dequeueing Policy:
+ *	If tx_qlen is different from 0 and the queue has reached its upper bound
+ *	of tx_qlen elements, replace older packets lowest-priority-first.
+ */
+static struct sk_buff *qpolicy_prio_best_skb(struct sock *sk)
+{
+	struct sk_buff *skb, *best = NULL;
+
+	skb_queue_walk(&sk->sk_write_queue, skb)
+		if (best == NULL || skb->priority > best->priority)
+			best = skb;
+	return best;
+}
+
+static struct sk_buff *qpolicy_prio_worst_skb(struct sock *sk)
+{
+	struct sk_buff *skb, *worst = NULL;
+
+	skb_queue_walk(&sk->sk_write_queue, skb)
+		if (worst == NULL || skb->priority < worst->priority)
+			worst = skb;
+	return worst;
+}
+
+static bool qpolicy_prio_full(struct sock *sk)
+{
+	if (qpolicy_simple_full(sk))
+		dccp_qpolicy_drop(sk, qpolicy_prio_worst_skb(sk));
+	return false;
+}
+
+/**
+ * struct dccp_qpolicy_operations  -  TX Packet Dequeueing Interface
+ * @push: add a new @skb to the write queue
+ * @full: indicates that no more packets will be admitted
+ * @top:  peeks at whatever the queueing policy defines as its `top'
+ */
+static struct dccp_qpolicy_operations {
+	void		(*push)	(struct sock *sk, struct sk_buff *skb);
+	bool		(*full) (struct sock *sk);
+	struct sk_buff*	(*top)  (struct sock *sk);
+	__be32		params;
+
+} qpol_table[DCCPQ_POLICY_MAX] = {
+	[DCCPQ_POLICY_SIMPLE] = {
+		.push   = qpolicy_simple_push,
+		.full   = qpolicy_simple_full,
+		.top    = qpolicy_simple_top,
+		.params = 0,
+	},
+	[DCCPQ_POLICY_PRIO] = {
+		.push   = qpolicy_simple_push,
+		.full   = qpolicy_prio_full,
+		.top    = qpolicy_prio_best_skb,
+		.params = DCCP_SCM_PRIORITY,
+	},
+};
+
+/*
+ *	Externally visible interface
+ */
+void dccp_qpolicy_push(struct sock *sk, struct sk_buff *skb)
+{
+	qpol_table[dccp_sk(sk)->dccps_qpolicy].push(sk, skb);
+}
+
+bool dccp_qpolicy_full(struct sock *sk)
+{
+	return qpol_table[dccp_sk(sk)->dccps_qpolicy].full(sk);
+}
+
+void dccp_qpolicy_drop(struct sock *sk, struct sk_buff *skb)
+{
+	if (skb != NULL) {
+		skb_unlink(skb, &sk->sk_write_queue);
+		kfree_skb(skb);
+	}
+}
+
+struct sk_buff *dccp_qpolicy_top(struct sock *sk)
+{
+	return qpol_table[dccp_sk(sk)->dccps_qpolicy].top(sk);
+}
+
+struct sk_buff *dccp_qpolicy_pop(struct sock *sk)
+{
+	struct sk_buff *skb = dccp_qpolicy_top(sk);
+
+	if (skb != NULL) {
+		/* Clear any skb fields that we used internally */
+		skb->priority = 0;
+		skb_unlink(skb, &sk->sk_write_queue);
+	}
+	return skb;
+}
+
+bool dccp_qpolicy_param_ok(struct sock *sk, __be32 param)
+{
+	/* check if exactly one bit is set */
+	if (!param || (param & (param - 1)))
+		return false;
+	return (qpol_table[dccp_sk(sk)->dccps_qpolicy].params & param) == param;
+}