[GitHub/mt8127/android_kernel_alcatel_ttab.git] / net / dccp / ackvec.c

/*
 *  net/dccp/ackvec.c
 *
 *  An implementation of the DCCP protocol
 *  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/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_record *avr =
			kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC);

	if (avr != NULL)
		INIT_LIST_HEAD(&avr->avr_node);

	return avr;
}

static void dccp_ackvec_record_delete(struct dccp_ackvec_record *avr)
{
	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);
}

static void dccp_ackvec_insert_avr(struct dccp_ackvec *av,
				   struct dccp_ackvec_record *avr)
{
	/*
	 * 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));
	}

	list_add(&avr->avr_node, &av->av_records);
}

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;
	/* Figure out how many options do we need to represent the ackvec */
	const u16 nr_opts = DIV_ROUND_UP(av->av_vec_len, DCCP_MAX_ACKVEC_OPT_LEN);
	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(sk, skb, elapsed_time))
		return -1;

	avr = dccp_ackvec_record_new();
	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_MAX_ACKVEC_OPT_LEN)
			copylen = DCCP_MAX_ACKVEC_OPT_LEN;

		*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;
	}

	/*
	 *	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.
	 */
	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);

	dccp_pr_debug("%s ACK Vector 0, len=%d, ack_seqno=%llu, "
		      "ack_ackno=%llu\n",
		      dccp_role(sk), avr->avr_sent_len,
		      (unsigned long long)avr->avr_ack_seqno,
		      (unsigned long long)avr->avr_ack_ackno);
	return 0;
}

struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
{
	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);
	}

	return av;
}

void dccp_ackvec_free(struct dccp_ackvec *av)
{
	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);
}

static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av,
				   const u32 index)
{
	return av->av_buf[index] & DCCP_ACKVEC_STATE_MASK;
}

static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av,
				 const u32 index)
{
	return av->av_buf[index] & DCCP_ACKVEC_LEN_MASK;
}

/*
 * 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)
{
	unsigned int gap;
	long new_head;

	if (av->av_vec_len + packets > DCCP_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, DCCP_ACKVEC_STATE_NOT_RECEIVED,
			       gap + new_head + 1);
			gap = -new_head;
		}
		new_head += DCCP_MAX_ACKVEC_LEN;
	}

	av->av_buf_head = new_head;

	if (gap > 0)
		memset(av->av_buf + av->av_buf_head + 1,
		       DCCP_ACKVEC_STATE_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)
{
	/*
	 * 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) {
		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);

		/*
		 * 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(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;

		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_ackno = ackno;
	av->av_time = ktime_get_real();
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 = DCCP_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_init(&avr->avr_node);
		dccp_ackvec_record_delete(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), 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 */
	}
}

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 = *vector & DCCP_ACKVEC_LEN_MASK;
		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)) {
			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.
			 */
		}

		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_MAX_ACKVEC_OPT_LEN)
		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;
	}
}
Commit	Line	Data
ae31c339 ACM	1	/*
	2	* net/dccp/ackvec.c
	3	*
410e27a4	4	* An implementation of the DCCP protocol
ae31c339 ACM	5	* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
	6	*
	7	* This program is free software; you can redistribute it and/or modify it
	8	* under the terms of the GNU General Public License as published by the
	9	* Free Software Foundation; version 2 of the License;
	10	*/
410e27a4 GR	11
410e27a4 GR	12	#include "ackvec.h"
ae31c339	13	#include "dccp.h"
410e27a4 GR	14
	15	#include <linux/dccp.h>
	16	#include <linux/init.h>
	17	#include <linux/errno.h>
9b07ef5d	18	#include <linux/kernel.h>
410e27a4	19	#include <linux/skbuff.h>
9b07ef5d	20	#include <linux/slab.h>
ae31c339	21
410e27a4 GR	22	#include <net/sock.h>
410e27a4 GR	23
e18b890b CL	24	static struct kmem_cache *dccp_ackvec_slab;
e18b890b CL	25	static struct kmem_cache *dccp_ackvec_record_slab;
02bcf28c	26
410e27a4	27	static struct dccp_ackvec_record *dccp_ackvec_record_new(void)
02bcf28c	28	{
410e27a4 GR	29	struct dccp_ackvec_record *avr =
410e27a4 GR	30	kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC);
ff49e270	31
410e27a4 GR	32	if (avr != NULL)
	33	INIT_LIST_HEAD(&avr->avr_node);
	34
	35	return avr;
ff49e270	36	}
02bcf28c	37
410e27a4	38	static void dccp_ackvec_record_delete(struct dccp_ackvec_record *avr)
ff49e270	39	{
410e27a4 GR	40	if (unlikely(avr == NULL))
	41	return;
	42	/* Check if deleting a linked record */
	43	WARN_ON(!list_empty(&avr->avr_node));
	44	kmem_cache_free(dccp_ackvec_record_slab, avr);
02bcf28c AB	45	}
02bcf28c AB	46
410e27a4 GR	47	static void dccp_ackvec_insert_avr(struct dccp_ackvec *av,
410e27a4 GR	48	struct dccp_ackvec_record *avr)
02bcf28c	49	{
410e27a4 GR	50	/*
	51	* AVRs are sorted by seqno. Since we are sending them in order, we
	52	* just add the AVR at the head of the list.
	53	* -sorbo.
	54	*/
	55	if (!list_empty(&av->av_records)) {
	56	const struct dccp_ackvec_record *head =
	57	list_entry(av->av_records.next,
	58	struct dccp_ackvec_record,
	59	avr_node);
	60	BUG_ON(before48(avr->avr_ack_seqno, head->avr_ack_seqno));
ff49e270	61	}
410e27a4 GR	62
410e27a4 GR	63	list_add(&avr->avr_node, &av->av_records);
02bcf28c AB	64	}
02bcf28c AB	65
410e27a4	66	int dccp_insert_option_ackvec(struct sock sk, struct sk_buff skb)
ae31c339	67	{
410e27a4 GR	68	struct dccp_sock *dp = dccp_sk(sk);
	69	struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
	70	/* Figure out how many options do we need to represent the ackvec */
	71	const u16 nr_opts = DIV_ROUND_UP(av->av_vec_len, DCCP_MAX_ACKVEC_OPT_LEN);
	72	u16 len = av->av_vec_len + 2 * nr_opts, i;
	73	u32 elapsed_time;
	74	const unsigned char tail, from;
	75	unsigned char *to;
02bcf28c	76	struct dccp_ackvec_record *avr;
410e27a4 GR	77	suseconds_t delta;
	78
	79	if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
	80	return -1;
	81
	82	delta = ktime_us_delta(ktime_get_real(), av->av_time);
	83	elapsed_time = delta / 10;
02bcf28c	84
410e27a4 GR	85	if (elapsed_time != 0 &&
	86	dccp_insert_option_elapsed_time(sk, skb, elapsed_time))
	87	return -1;
	88
	89	avr = dccp_ackvec_record_new();
2d0817d1	90	if (avr == NULL)
410e27a4 GR	91	return -1;
	92
	93	DCCP_SKB_CB(skb)->dccpd_opt_len += len;
	94
	95	to = skb_push(skb, len);
	96	len = av->av_vec_len;
	97	from = av->av_buf + av->av_buf_head;
	98	tail = av->av_buf + DCCP_MAX_ACKVEC_LEN;
	99
	100	for (i = 0; i < nr_opts; ++i) {
	101	int copylen = len;
	102
	103	if (len > DCCP_MAX_ACKVEC_OPT_LEN)
	104	copylen = DCCP_MAX_ACKVEC_OPT_LEN;
	105
	106	*to++ = DCCPO_ACK_VECTOR_0;
	107	*to++ = copylen + 2;
	108
	109	/* Check if buf_head wraps */
	110	if (from + copylen > tail) {
	111	const u16 tailsize = tail - from;
	112
	113	memcpy(to, from, tailsize);
	114	to += tailsize;
	115	len -= tailsize;
	116	copylen -= tailsize;
	117	from = av->av_buf;
	118	}
	119
	120	memcpy(to, from, copylen);
	121	from += copylen;
	122	to += copylen;
	123	len -= copylen;
	124	}
ae31c339	125
4829007c	126	/*
410e27a4 GR	127	* From RFC 4340, A.2:
	128	*
	129	* For each acknowledgement it sends, the HC-Receiver will add an
	130	* acknowledgement record. ack_seqno will equal the HC-Receiver
	131	* sequence number it used for the ack packet; ack_ptr will equal
	132	* buf_head; ack_ackno will equal buf_ackno; and ack_nonce will
	133	* equal buf_nonce.
4829007c	134	*/
410e27a4 GR	135	avr->avr_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
	136	avr->avr_ack_ptr = av->av_buf_head;
	137	avr->avr_ack_ackno = av->av_buf_ackno;
	138	avr->avr_ack_nonce = av->av_buf_nonce;
	139	avr->avr_sent_len = av->av_vec_len;
02bcf28c	140
410e27a4 GR	141	dccp_ackvec_insert_avr(av, avr);
	142
	143	dccp_pr_debug("%s ACK Vector 0, len=%d, ack_seqno=%llu, "
	144	"ack_ackno=%llu\n",
	145	dccp_role(sk), avr->avr_sent_len,
a47c5104	146	(unsigned long long)avr->avr_ack_seqno,
410e27a4	147	(unsigned long long)avr->avr_ack_ackno);
02bcf28c	148	return 0;
ae31c339 ACM	149	}
ae31c339 ACM	150
410e27a4	151	struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
68b1de15	152	{
410e27a4 GR	153	struct dccp_ackvec *av = kmem_cache_alloc(dccp_ackvec_slab, priority);
	154
	155	if (av != NULL) {
	156	av->av_buf_head = DCCP_MAX_ACKVEC_LEN - 1;
	157	av->av_buf_ackno = UINT48_MAX + 1;
	158	av->av_buf_nonce = 0;
	159	av->av_time = ktime_set(0, 0);
	160	av->av_vec_len = 0;
	161	INIT_LIST_HEAD(&av->av_records);
68b1de15	162	}
410e27a4 GR	163
410e27a4 GR	164	return av;
68b1de15 GR	165	}
68b1de15 GR	166
410e27a4	167	void dccp_ackvec_free(struct dccp_ackvec *av)
d7dc7e5f	168	{
410e27a4 GR	169	if (unlikely(av == NULL))
	170	return;
	171
	172	if (!list_empty(&av->av_records)) {
	173	struct dccp_ackvec_record avr, next;
	174
	175	list_for_each_entry_safe(avr, next, &av->av_records, avr_node) {
	176	list_del_init(&avr->avr_node);
	177	dccp_ackvec_record_delete(avr);
	178	}
	179	}
	180
	181	kmem_cache_free(dccp_ackvec_slab, av);
d7dc7e5f GR	182	}
d7dc7e5f GR	183
410e27a4 GR	184	static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av,
410e27a4 GR	185	const u32 index)
d7dc7e5f	186	{
410e27a4	187	return av->av_buf[index] & DCCP_ACKVEC_STATE_MASK;
d7dc7e5f GR	188	}
d7dc7e5f GR	189
410e27a4 GR	190	static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av,
410e27a4 GR	191	const u32 index)
d7dc7e5f	192	{
410e27a4	193	return av->av_buf[index] & DCCP_ACKVEC_LEN_MASK;
d7dc7e5f GR	194	}
d7dc7e5f GR	195
410e27a4 GR	196	/*
	197	* If several packets are missing, the HC-Receiver may prefer to enter multiple
	198	* bytes with run length 0, rather than a single byte with a larger run length;
	199	* this simplifies table updates if one of the missing packets arrives.
e28fe59f	200	*/
410e27a4 GR	201	static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av,
	202	const unsigned int packets,
	203	const unsigned char state)
e28fe59f	204	{
410e27a4 GR	205	unsigned int gap;
410e27a4 GR	206	long new_head;
e28fe59f	207
410e27a4 GR	208	if (av->av_vec_len + packets > DCCP_MAX_ACKVEC_LEN)
410e27a4 GR	209	return -ENOBUFS;
e28fe59f	210
410e27a4 GR	211	gap = packets - 1;
410e27a4 GR	212	new_head = av->av_buf_head - packets;
e28fe59f	213
410e27a4 GR	214	if (new_head < 0) {
	215	if (gap > 0) {
	216	memset(av->av_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED,
	217	gap + new_head + 1);
	218	gap = -new_head;
e28fe59f	219	}
410e27a4 GR	220	new_head += DCCP_MAX_ACKVEC_LEN;
410e27a4 GR	221	}
e28fe59f	222
410e27a4	223	av->av_buf_head = new_head;
e28fe59f	224
410e27a4 GR	225	if (gap > 0)
	226	memset(av->av_buf + av->av_buf_head + 1,
	227	DCCP_ACKVEC_STATE_NOT_RECEIVED, gap);
e28fe59f	228
410e27a4 GR	229	av->av_buf[av->av_buf_head] = state;
	230	av->av_vec_len += packets;
	231	return 0;
e28fe59f GR	232	}
e28fe59f GR	233
410e27a4 GR	234	/*
410e27a4 GR	235	* Implements the RFC 4340, Appendix A
e28fe59f	236	*/
410e27a4 GR	237	int dccp_ackvec_add(struct dccp_ackvec av, const struct sock sk,
410e27a4 GR	238	const u64 ackno, const u8 state)
e28fe59f	239	{
410e27a4 GR	240	/*
	241	* Check at the right places if the buffer is full, if it is, tell the
	242	* caller to start dropping packets till the HC-Sender acks our ACK
	243	* vectors, when we will free up space in av_buf.
	244	*
	245	* We may well decide to do buffer compression, etc, but for now lets
	246	* just drop.
	247	*
	248	* From Appendix A.1.1 (`New Packets'):
	249	*
	250	* Of course, the circular buffer may overflow, either when the
	251	* HC-Sender is sending data at a very high rate, when the
	252	* HC-Receiver's acknowledgements are not reaching the HC-Sender,
	253	* or when the HC-Sender is forgetting to acknowledge those acks
	254	* (so the HC-Receiver is unable to clean up old state). In this
	255	* case, the HC-Receiver should either compress the buffer (by
	256	* increasing run lengths when possible), transfer its state to
	257	* a larger buffer, or, as a last resort, drop all received
	258	* packets, without processing them whatsoever, until its buffer
	259	* shrinks again.
	260	*/
e28fe59f	261
410e27a4 GR	262	/* See if this is the first ackno being inserted */
	263	if (av->av_vec_len == 0) {
	264	av->av_buf[av->av_buf_head] = state;
	265	av->av_vec_len = 1;
	266	} else if (after48(ackno, av->av_buf_ackno)) {
	267	const u64 delta = dccp_delta_seqno(av->av_buf_ackno, ackno);
e28fe59f	268
e28fe59f	269	/*
410e27a4 GR	270	* Look if the state of this packet is the same as the
410e27a4 GR	271	* previous ackno and if so if we can bump the head len.
e28fe59f	272	*/
410e27a4 GR	273	if (delta == 1 &&
	274	dccp_ackvec_state(av, av->av_buf_head) == state &&
	275	dccp_ackvec_len(av, av->av_buf_head) < DCCP_ACKVEC_LEN_MASK)
	276	av->av_buf[av->av_buf_head]++;
	277	else if (dccp_ackvec_set_buf_head_state(av, delta, state))
	278	return -ENOBUFS;
	279	} else {
	280	/*
	281	* A.1.2. Old Packets
	282	*
	283	* When a packet with Sequence Number S <= buf_ackno
	284	* arrives, the HC-Receiver will scan the table for
	285	* the byte corresponding to S. (Indexing structures
	286	* could reduce the complexity of this scan.)
	287	*/
	288	u64 delta = dccp_delta_seqno(ackno, av->av_buf_ackno);
	289	u32 index = av->av_buf_head;
e28fe59f	290
410e27a4 GR	291	while (1) {
	292	const u8 len = dccp_ackvec_len(av, index);
	293	const u8 av_state = dccp_ackvec_state(av, index);
	294	/*
	295	* valid packets not yet in av_buf have a reserved
	296	* entry, with a len equal to 0.
	297	*/
	298	if (av_state == DCCP_ACKVEC_STATE_NOT_RECEIVED &&
	299	len == 0 && delta == 0) { /* Found our
	300	reserved seat! */
	301	dccp_pr_debug("Found %llu reserved seat!\n",
	302	(unsigned long long)ackno);
	303	av->av_buf[index] = state;
	304	goto out;
	305	}
	306	/* len == 0 means one packet */
	307	if (delta < len + 1)
	308	goto out_duplicate;
	309
	310	delta -= len + 1;
	311	if (++index == DCCP_MAX_ACKVEC_LEN)
	312	index = 0;
e28fe59f GR	313	}
	314	}
	315
410e27a4 GR	316	av->av_buf_ackno = ackno;
	317	av->av_time = ktime_get_real();
	318	out:
	319	return 0;
e28fe59f	320
410e27a4 GR	321	out_duplicate:
	322	/* Duplicate packet */
	323	dccp_pr_debug("Received a dup or already considered lost "
	324	"packet: %llu\n", (unsigned long long)ackno);
	325	return -EILSEQ;
e28fe59f GR	326	}
e28fe59f GR	327
410e27a4 GR	328	static void dccp_ackvec_throw_record(struct dccp_ackvec *av,
410e27a4 GR	329	struct dccp_ackvec_record *avr)
e28fe59f	330	{
410e27a4	331	struct dccp_ackvec_record *next;
e28fe59f	332
410e27a4 GR	333	/* sort out vector length */
	334	if (av->av_buf_head <= avr->avr_ack_ptr)
	335	av->av_vec_len = avr->avr_ack_ptr - av->av_buf_head;
	336	else
	337	av->av_vec_len = DCCP_MAX_ACKVEC_LEN - 1 -
	338	av->av_buf_head + avr->avr_ack_ptr;
e28fe59f	339
410e27a4 GR	340	/* free records */
	341	list_for_each_entry_safe_from(avr, next, &av->av_records, avr_node) {
	342	list_del_init(&avr->avr_node);
	343	dccp_ackvec_record_delete(avr);
	344	}
	345	}
e28fe59f	346
410e27a4 GR	347	void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec av, struct sock sk,
	348	const u64 ackno)
	349	{
	350	struct dccp_ackvec_record *avr;
e28fe59f	351
410e27a4 GR	352	/*
	353	* If we traverse backwards, it should be faster when we have large
	354	* windows. We will be receiving ACKs for stuff we sent a while back
	355	* -sorbo.
	356	*/
	357	list_for_each_entry_reverse(avr, &av->av_records, avr_node) {
	358	if (ackno == avr->avr_ack_seqno) {
	359	dccp_pr_debug("%s ACK packet 0, len=%d, ack_seqno=%llu, "
	360	"ack_ackno=%llu, ACKED!\n",
	361	dccp_role(sk), 1,
	362	(unsigned long long)avr->avr_ack_seqno,
	363	(unsigned long long)avr->avr_ack_ackno);
	364	dccp_ackvec_throw_record(av, avr);
	365	break;
	366	} else if (avr->avr_ack_seqno > ackno)
	367	break; /* old news */
e28fe59f GR	368	}
	369	}
	370
410e27a4 GR	371	static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
	372	struct sock sk, u64 ackno,
	373	const unsigned char len,
	374	const unsigned char *vector)
	375	{
	376	unsigned char i;
	377	struct dccp_ackvec_record *avr;
68b1de15	378
410e27a4 GR	379	/* Check if we actually sent an ACK vector */
410e27a4 GR	380	if (list_empty(&av->av_records))
68b1de15	381	return;
68b1de15	382
410e27a4	383	i = len;
68b1de15	384	/*
410e27a4 GR	385	* XXX
	386	* I think it might be more efficient to work backwards. See comment on
	387	* rcv_ackno. -sorbo.
68b1de15	388	*/
410e27a4 GR	389	avr = list_entry(av->av_records.next, struct dccp_ackvec_record, avr_node);
	390	while (i--) {
	391	const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
	392	u64 ackno_end_rl;
68b1de15	393
410e27a4	394	dccp_set_seqno(&ackno_end_rl, *ackno - rl);
68b1de15	395
68b1de15	396	/*
410e27a4 GR	397	* If our AVR sequence number is greater than the ack, go
410e27a4 GR	398	* forward in the AVR list until it is not so.
68b1de15	399	*/
410e27a4 GR	400	list_for_each_entry_from(avr, &av->av_records, avr_node) {
	401	if (!after48(avr->avr_ack_seqno, *ackno))
	402	goto found;
	403	}
	404	/* End of the av_records list, not found, exit */
	405	break;
	406	found:
	407	if (between48(avr->avr_ack_seqno, ackno_end_rl, *ackno)) {
	408	const u8 state = *vector & DCCP_ACKVEC_STATE_MASK;
	409	if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) {
	410	dccp_pr_debug("%s ACK vector 0, len=%d, "
	411	"ack_seqno=%llu, ack_ackno=%llu, "
	412	"ACKED!\n",
	413	dccp_role(sk), len,
	414	(unsigned long long)
	415	avr->avr_ack_seqno,
	416	(unsigned long long)
	417	avr->avr_ack_ackno);
	418	dccp_ackvec_throw_record(av, avr);
	419	break;
	420	}
	421	/*
	422	* If it wasn't received, continue scanning... we might
	423	* find another one.
	424	*/
	425	}
68b1de15	426
410e27a4 GR	427	dccp_set_seqno(ackno, ackno_end_rl - 1);
410e27a4 GR	428	++vector;
68b1de15 GR	429	}
	430	}
	431
410e27a4 GR	432	int dccp_ackvec_parse(struct sock sk, const struct sk_buff skb,
410e27a4 GR	433	u64 ackno, const u8 opt, const u8 value, const u8 len)
c8bf462b	434	{
410e27a4 GR	435	if (len > DCCP_MAX_ACKVEC_OPT_LEN)
410e27a4 GR	436	return -1;
c8bf462b	437
410e27a4 GR	438	/* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */
	439	dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk,
	440	ackno, len, value);
c8bf462b GR	441	return 0;
c8bf462b GR	442	}
c8bf462b	443
9b07ef5d ACM	444	int __init dccp_ackvec_init(void)
	445	{
	446	dccp_ackvec_slab = kmem_cache_create("dccp_ackvec",
	447	sizeof(struct dccp_ackvec), 0,
20c2df83	448	SLAB_HWCACHE_ALIGN, NULL);
02bcf28c AB	449	if (dccp_ackvec_slab == NULL)
	450	goto out_err;
	451
410e27a4 GR	452	dccp_ackvec_record_slab =
	453	kmem_cache_create("dccp_ackvec_record",
	454	sizeof(struct dccp_ackvec_record),
	455	0, SLAB_HWCACHE_ALIGN, NULL);
02bcf28c AB	456	if (dccp_ackvec_record_slab == NULL)
02bcf28c AB	457	goto out_destroy_slab;
9b07ef5d ACM	458
9b07ef5d ACM	459	return 0;
02bcf28c AB	460
	461	out_destroy_slab:
	462	kmem_cache_destroy(dccp_ackvec_slab);
	463	dccp_ackvec_slab = NULL;
	464	out_err:
59348b19	465	DCCP_CRIT("Unable to create Ack Vector slab cache");
02bcf28c	466	return -ENOBUFS;
9b07ef5d ACM	467	}
	468
	469	void dccp_ackvec_exit(void)
	470	{
	471	if (dccp_ackvec_slab != NULL) {
	472	kmem_cache_destroy(dccp_ackvec_slab);
	473	dccp_ackvec_slab = NULL;
	474	}
02bcf28c AB	475	if (dccp_ackvec_record_slab != NULL) {
	476	kmem_cache_destroy(dccp_ackvec_record_slab);
	477	dccp_ackvec_record_slab = NULL;
	478	}
9b07ef5d	479	}