net/dccp/ackvec.c - kernel/msm-4.9 - Gitiles

 /*
  *  net/dccp/ackvec.c
  *
  *  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;

 struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
 {
 	struct dccp_ackvec *av = kmem_cache_zalloc(dccp_ackvec_slab, priority);

 	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_purge_records(struct dccp_ackvec *av)
 {
 	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);
 }

 void dccp_ackvec_free(struct dccp_ackvec *av)
 {
 	if (likely(av != NULL)) {
 		dccp_ackvec_purge_records(av);
 		kmem_cache_free(dccp_ackvec_slab, av);
 	}
 }

 /**
  * 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_ackvec_record *avr;

 	avr = kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC);
 	if (avr == NULL)
 		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);
 	/*
 	 * 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.
 	 */
 	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("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,
 		      avr->avr_ack_runlen);
 	return 0;
 }

 /*
  * 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)
 {
 	return (a + b) % DCCPAV_MAX_ACKVEC_LEN;
 }

 static inline u16 __ackvec_idx_sub(const u16 a, const u16 b)
 {
 	return __ackvec_idx_add(a, DCCPAV_MAX_ACKVEC_LEN - b);
 }

 u16 dccp_ackvec_buflen(const struct dccp_ackvec *av)
 {
 	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.
  */
 static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av,
 						 const unsigned int packets,
 						 const unsigned char state)
 {
 	long gap;
 	long new_head;

 	if (av->av_vec_len + packets > DCCPAV_MAX_ACKVEC_LEN)
 		return -ENOBUFS;

 	gap	 = packets - 1;
 	new_head = av->av_buf_head - packets;

 	if (new_head < 0) {
 		if (gap > 0) {
 			memset(av->av_buf, DCCPAV_NOT_RECEIVED,
 			       gap + new_head + 1);
 			gap = -new_head;
 		}
 		new_head += DCCPAV_MAX_ACKVEC_LEN;
 	}

 	av->av_buf_head = new_head;

 	if (gap > 0)
 		memset(av->av_buf + av->av_buf_head + 1,
 		       DCCPAV_NOT_RECEIVED, gap);

 	av->av_buf[av->av_buf_head] = state;
 	av->av_vec_len += packets;
 	return 0;
 }

 /*
  * Implements the RFC 4340, Appendix A
  */
 int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
 		    const u64 ackno, const u8 state)
 {
 	u8 *cur_head = av->av_buf + av->av_buf_head,
 	   *buf_end  = av->av_buf + DCCPAV_MAX_ACKVEC_LEN;
 	/*
 	 * 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.
 	 */

 	/* See if this is the first ackno being inserted */
 	if (av->av_vec_len == 0) {
 		*cur_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);

 		/*
 		 * Look if the state of this packet is the same as the
 		 * previous ackno and if so if we can bump the head len.
 		 */
 		if (delta == 1 && dccp_ackvec_state(cur_head) == state &&
 		    dccp_ackvec_runlen(cur_head) < DCCPAV_MAX_RUNLEN)
 			*cur_head += 1;
 		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);

 		while (1) {
 			const u8 len = dccp_ackvec_runlen(cur_head);
 			/*
 			 * valid packets not yet in av_buf have a reserved
 			 * entry, with a len equal to 0.
 			 */
 			if (*cur_head == DCCPAV_NOT_RECEIVED && delta == 0) {
 				dccp_pr_debug("Found %llu reserved seat!\n",
 					      (unsigned long long)ackno);
 				*cur_head = state;
 				goto out;
 			}
 			/* len == 0 means one packet */
 			if (delta < len + 1)
 				goto out_duplicate;

 			delta -= len + 1;
 			if (++cur_head == buf_end)
 				cur_head = av->av_buf;
 		}
 	}

 	av->av_buf_ackno = ackno;
 out:
 	return 0;

 out_duplicate:
 	/* Duplicate packet */
 	dccp_pr_debug("Received a dup or already considered lost "
 		      "packet: %llu\n", (unsigned long long)ackno);
 	return -EILSEQ;
 }

 static void dccp_ackvec_throw_record(struct dccp_ackvec *av,
 				     struct dccp_ackvec_record *avr)
 {
 	struct dccp_ackvec_record *next;

 	/* 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 = DCCPAV_MAX_ACKVEC_LEN - 1 -
 				 av->av_buf_head + avr->avr_ack_ptr;

 	/* 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);
 	}
 }

 void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk,
 				 const u64 ackno)
 {
 	struct dccp_ackvec_record *avr;

 	/*
 	 * 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), avr->avr_ack_runlen,
 				      (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 */
 	}
 }

 static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
 					    struct sock *sk, u64 *ackno,
 					    const unsigned char len,
 					    const unsigned char *vector)
 {
 	unsigned char i;
 	struct dccp_ackvec_record *avr;

 	/* Check if we actually sent an ACK vector */
 	if (list_empty(&av->av_records))
 		return;

 	i = len;
 	/*
 	 * XXX
 	 * I think it might be more efficient to work backwards. See comment on
 	 * rcv_ackno. -sorbo.
 	 */
 	avr = list_entry(av->av_records.next, struct dccp_ackvec_record, avr_node);
 	while (i--) {
 		const u8 rl = dccp_ackvec_runlen(vector);
 		u64 ackno_end_rl;

 		dccp_set_seqno(&ackno_end_rl, *ackno - rl);

 		/*
 		 * If our AVR sequence number is greater than the ack, go
 		 * forward in the AVR list until it is not so.
 		 */
 		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)) {
 			if (dccp_ackvec_state(vector) != DCCPAV_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.
 			 */
 		}

 		dccp_set_seqno(ackno, ackno_end_rl - 1);
 		++vector;
 	}
 }

 int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
 		      u64 *ackno, const u8 opt, const u8 *value, const u8 len)
 {
 	if (len > DCCP_SINGLE_OPT_MAXLEN)
 		return -1;

 	/* 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);
 	return 0;
 }

 int __init dccp_ackvec_init(void)
 {
 	dccp_ackvec_slab = kmem_cache_create("dccp_ackvec",
 					     sizeof(struct dccp_ackvec), 0,
 					     SLAB_HWCACHE_ALIGN, NULL);
 	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);
 	if (dccp_ackvec_record_slab == NULL)
 		goto out_destroy_slab;

 	return 0;

 out_destroy_slab:
 	kmem_cache_destroy(dccp_ackvec_slab);
 	dccp_ackvec_slab = NULL;
 out_err:
 	DCCP_CRIT("Unable to create Ack Vector slab cache");
 	return -ENOBUFS;
 }

 void dccp_ackvec_exit(void)
 {
 	if (dccp_ackvec_slab != NULL) {
 		kmem_cache_destroy(dccp_ackvec_slab);
 		dccp_ackvec_slab = NULL;
 	}
 	if (dccp_ackvec_record_slab != NULL) {
 		kmem_cache_destroy(dccp_ackvec_record_slab);
 		dccp_ackvec_record_slab = NULL;
 	}
 }
	/*
	* net/dccp/ackvec.c
	*
	* 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;

	struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
	{
	struct dccp_ackvec *av = kmem_cache_zalloc(dccp_ackvec_slab, priority);

	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_purge_records(struct dccp_ackvec *av)
	{
	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);
	}

	void dccp_ackvec_free(struct dccp_ackvec *av)
	{
	if (likely(av != NULL)) {
	dccp_ackvec_purge_records(av);
	kmem_cache_free(dccp_ackvec_slab, av);
	}
	}

	/**
	* 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_ackvec_record *avr;

	avr = kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC);
	if (avr == NULL)
	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);
	/*
	* 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.
	*/
	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("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,
	avr->avr_ack_runlen);
	return 0;
	}

	/*
	* 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)
	{
	return (a + b) % DCCPAV_MAX_ACKVEC_LEN;
	}

	static inline u16 __ackvec_idx_sub(const u16 a, const u16 b)
	{
	return __ackvec_idx_add(a, DCCPAV_MAX_ACKVEC_LEN - b);
	}

	u16 dccp_ackvec_buflen(const struct dccp_ackvec *av)
	{
	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.
	*/
	static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av,
	const unsigned int packets,
	const unsigned char state)
	{
	long gap;
	long new_head;

	if (av->av_vec_len + packets > DCCPAV_MAX_ACKVEC_LEN)
	return -ENOBUFS;

	gap = packets - 1;
	new_head = av->av_buf_head - packets;

	if (new_head < 0) {
	if (gap > 0) {
	memset(av->av_buf, DCCPAV_NOT_RECEIVED,
	gap + new_head + 1);
	gap = -new_head;
	}
	new_head += DCCPAV_MAX_ACKVEC_LEN;
	}

	av->av_buf_head = new_head;

	if (gap > 0)
	memset(av->av_buf + av->av_buf_head + 1,
	DCCPAV_NOT_RECEIVED, gap);

	av->av_buf[av->av_buf_head] = state;
	av->av_vec_len += packets;
	return 0;
	}

	/*
	* Implements the RFC 4340, Appendix A
	*/
	int dccp_ackvec_add(struct dccp_ackvec av, const struct sock sk,
	const u64 ackno, const u8 state)
	{
	u8 *cur_head = av->av_buf + av->av_buf_head,
	*buf_end = av->av_buf + DCCPAV_MAX_ACKVEC_LEN;
	/*
	* 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.
	*/

	/* See if this is the first ackno being inserted */
	if (av->av_vec_len == 0) {
	*cur_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);

	/*
	* Look if the state of this packet is the same as the
	* previous ackno and if so if we can bump the head len.
	*/
	if (delta == 1 && dccp_ackvec_state(cur_head) == state &&
	dccp_ackvec_runlen(cur_head) < DCCPAV_MAX_RUNLEN)
	*cur_head += 1;
	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);

	while (1) {
	const u8 len = dccp_ackvec_runlen(cur_head);
	/*
	* valid packets not yet in av_buf have a reserved
	* entry, with a len equal to 0.
	*/
	if (*cur_head == DCCPAV_NOT_RECEIVED && delta == 0) {
	dccp_pr_debug("Found %llu reserved seat!\n",
	(unsigned long long)ackno);
	*cur_head = state;
	goto out;
	}
	/* len == 0 means one packet */
	if (delta < len + 1)
	goto out_duplicate;

	delta -= len + 1;
	if (++cur_head == buf_end)
	cur_head = av->av_buf;
	}
	}

	av->av_buf_ackno = ackno;
	out:
	return 0;

	out_duplicate:
	/* Duplicate packet */
	dccp_pr_debug("Received a dup or already considered lost "
	"packet: %llu\n", (unsigned long long)ackno);
	return -EILSEQ;
	}

	static void dccp_ackvec_throw_record(struct dccp_ackvec *av,
	struct dccp_ackvec_record *avr)
	{
	struct dccp_ackvec_record *next;

	/* 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 = DCCPAV_MAX_ACKVEC_LEN - 1 -
	av->av_buf_head + avr->avr_ack_ptr;

	/* 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);
	}
	}

	void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec av, struct sock sk,
	const u64 ackno)
	{
	struct dccp_ackvec_record *avr;

	/*
	* 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), avr->avr_ack_runlen,
	(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 */
	}
	}

	static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
	struct sock sk, u64 ackno,
	const unsigned char len,
	const unsigned char *vector)
	{
	unsigned char i;
	struct dccp_ackvec_record *avr;

	/* Check if we actually sent an ACK vector */
	if (list_empty(&av->av_records))
	return;

	i = len;
	/*
	* XXX
	* I think it might be more efficient to work backwards. See comment on
	* rcv_ackno. -sorbo.
	*/
	avr = list_entry(av->av_records.next, struct dccp_ackvec_record, avr_node);
	while (i--) {
	const u8 rl = dccp_ackvec_runlen(vector);
	u64 ackno_end_rl;

	dccp_set_seqno(&ackno_end_rl, *ackno - rl);

	/*
	* If our AVR sequence number is greater than the ack, go
	* forward in the AVR list until it is not so.
	*/
	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)) {
	if (dccp_ackvec_state(vector) != DCCPAV_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.
	*/
	}

	dccp_set_seqno(ackno, ackno_end_rl - 1);
	++vector;
	}
	}

	int dccp_ackvec_parse(struct sock sk, const struct sk_buff skb,
	u64 ackno, const u8 opt, const u8 value, const u8 len)
	{
	if (len > DCCP_SINGLE_OPT_MAXLEN)
	return -1;

	/* 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);
	return 0;
	}

	int __init dccp_ackvec_init(void)
	{
	dccp_ackvec_slab = kmem_cache_create("dccp_ackvec",
	sizeof(struct dccp_ackvec), 0,
	SLAB_HWCACHE_ALIGN, NULL);
	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);
	if (dccp_ackvec_record_slab == NULL)
	goto out_destroy_slab;

	return 0;

	out_destroy_slab:
	kmem_cache_destroy(dccp_ackvec_slab);
	dccp_ackvec_slab = NULL;
	out_err:
	DCCP_CRIT("Unable to create Ack Vector slab cache");
	return -ENOBUFS;
	}

	void dccp_ackvec_exit(void)
	{
	if (dccp_ackvec_slab != NULL) {
	kmem_cache_destroy(dccp_ackvec_slab);
	dccp_ackvec_slab = NULL;
	}
	if (dccp_ackvec_record_slab != NULL) {
	kmem_cache_destroy(dccp_ackvec_record_slab);
	dccp_ackvec_record_slab = NULL;
	}
	}