/*
* 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
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);
-
- if (avr != NULL)
- INIT_LIST_HEAD(&avr->avr_node);
+ struct dccp_ackvec *av = kmem_cache_zalloc(dccp_ackvec_slab, priority);
- 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)
-{
- 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)
+/*
+ * 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);
}
/*
long gap;
long new_head;
- if (av->av_vec_len + packets > DCCP_MAX_ACKVEC_LEN)
+ if (av->av_vec_len + packets > DCCPAV_MAX_ACKVEC_LEN)
return -ENOBUFS;
gap = packets - 1;
if (new_head < 0) {
if (gap > 0) {
- memset(av->av_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED,
+ memset(av->av_buf, DCCPAV_NOT_RECEIVED,
gap + new_head + 1);
gap = -new_head;
}
- new_head += DCCP_MAX_ACKVEC_LEN;
+ new_head += DCCPAV_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);
+ DCCPAV_NOT_RECEIVED, gap);
av->av_buf[av->av_buf_head] = state;
av->av_vec_len += packets;
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
/* See if this is the first ackno being inserted */
if (av->av_vec_len == 0) {
- av->av_buf[av->av_buf_head] = state;
+ *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(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]++;
+ 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 {
* 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);
+ 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 (av_state == DCCP_ACKVEC_STATE_NOT_RECEIVED &&
- len == 0 && delta == 0) { /* Found our
- reserved seat! */
+ if (*cur_head == DCCPAV_NOT_RECEIVED && delta == 0) {
dccp_pr_debug("Found %llu reserved seat!\n",
(unsigned long long)ackno);
- av->av_buf[index] = state;
+ *cur_head = state;
goto out;
}
/* len == 0 means one packet */
goto out_duplicate;
delta -= len + 1;
- if (++index == DCCP_MAX_ACKVEC_LEN)
- index = 0;
+ if (++cur_head == buf_end)
+ cur_head = av->av_buf;
}
}
av->av_buf_ackno = ackno;
- av->av_time = ktime_get_real();
out:
return 0;
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_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_init(&avr->avr_node);
- dccp_ackvec_record_delete(avr);
+ list_del(&avr->avr_node);
+ kmem_cache_free(dccp_ackvec_record_slab, avr);
}
}
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,
+ 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);
*/
avr = list_entry(av->av_records.next, struct dccp_ackvec_record, avr_node);
while (i--) {
- const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
+ const u8 rl = dccp_ackvec_runlen(vector);
u64 ackno_end_rl;
dccp_set_seqno(&ackno_end_rl, *ackno - rl);
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) {
+ 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",
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;
/*
* 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.
#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)
+enum dccp_ackvec_states {
+ DCCPAV_RECEIVED = 0x00,
+ DCCPAV_ECN_MARKED = 0x40,
+ DCCPAV_RESERVED = 0x80,
+ DCCPAV_NOT_RECEIVED = 0xC0
+};
+#define DCCPAV_MAX_RUNLEN 0x3F
-#define DCCP_ACKVEC_STATE_MASK 0xC0 /* 11000000 */
-#define DCCP_ACKVEC_LEN_MASK 0x3F /* 00111111 */
+static inline u8 dccp_ackvec_runlen(const u8 *cell)
+{
+ return *cell & DCCPAV_MAX_RUNLEN;
+}
-/** 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_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)
+ * @av_veclen: length of the live portion of @av_buf
*/
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_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;
u16 av_vec_len;
- u8 av_buf_nonce;
- u8 av_ack_nonce;
- u8 av_buf[DCCP_MAX_ACKVEC_LEN];
};
-/** 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;
u64 *ackno, const u8 opt,
const u8 *value, const u8 len);
-extern int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb);
+extern int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum);
+extern u16 dccp_ackvec_buflen(const struct dccp_ackvec *av);
-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;
}
#endif /* _ACKVEC_H */
git://bbs.cooldavid.org / net-next-2.6.git / commitdiff