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[TFRC]: New rx history code

Browse Source 
Credit here goes to Gerrit Renker, that provided the initial implementation for
this new codebase.

I modified it just to try to make it closer to the existing API, renaming some
functions, add namespacing and fix one bug where the tfrc_rx_hist_alloc was not
freeing the allocated ring entries on the error path.

Original changeset comment from Gerrit:
      -----------
This provides a new, self-contained and generic RX history service for TFRC
based protocols.

Details:
 * new data structure, initialisation and cleanup routines;
 * allocation of dccp_rx_hist entries local to packet_history.c,
   as a service exported by the dccp_tfrc_lib module.
 * interface to automatically track highest-received seqno;
 * receiver-based RTT estimation (needed for instance by RFC 3448, 6.3.1);
 * a generic function to test for `data packets' as per  RFC 4340, sec. 7.7.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Arnaldo Carvalho de Melo 2007-12-06 13:18:11 -02:00 committed by David S. Miller
parent 30a0eacd47
commit b84a2189c4
5 changed files with 335 additions and 363 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

286
net/dccp/ccids/ccid3.c
View File

@ -641,6 +641,15 @@ static int ccid3_hc_tx_getsockopt(struct sock *sk, const int optname, int len,
/*
* Receiver Half-Connection Routines
*/
/* CCID3 feedback types */
enum ccid3_fback_type {
CCID3_FBACK_NONE = 0,
CCID3_FBACK_INITIAL,
CCID3_FBACK_PERIODIC,
CCID3_FBACK_PARAM_CHANGE
};
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state)
{
@ -667,59 +676,60 @@ static void ccid3_hc_rx_set_state(struct sock *sk,
hcrx->ccid3hcrx_state = state;
}
static inline void ccid3_hc_rx_update_s(struct ccid3_hc_rx_sock *hcrx, int len)
{
if (likely(len > 0)) /* don't update on empty packets (e.g. ACKs) */
hcrx->ccid3hcrx_s = tfrc_ewma(hcrx->ccid3hcrx_s, len, 9);
}
static void ccid3_hc_rx_send_feedback(struct sock *sk)
static void ccid3_hc_rx_send_feedback(struct sock *sk,
const struct sk_buff *skb,
enum ccid3_fback_type fbtype)
{
struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
struct dccp_sock *dp = dccp_sk(sk);
struct tfrc_rx_hist_entry *packet;
ktime_t now;
suseconds_t delta;
s64 delta = 0;
ccid3_pr_debug("%s(%p) - entry \n", dccp_role(sk), sk);
if (unlikely(hcrx->ccid3hcrx_state == TFRC_RSTATE_TERM))
return;
now = ktime_get_real();
switch (hcrx->ccid3hcrx_state) {
case TFRC_RSTATE_NO_DATA:
switch (fbtype) {
case CCID3_FBACK_INITIAL:
hcrx->ccid3hcrx_x_recv = 0;
hcrx->ccid3hcrx_pinv = ~0U; /* see RFC 4342, 8.5 */
break;
case TFRC_RSTATE_DATA:
delta = ktime_us_delta(now,
hcrx->ccid3hcrx_tstamp_last_feedback);
DCCP_BUG_ON(delta < 0);
case CCID3_FBACK_PARAM_CHANGE:
/*
* When parameters change (new loss or p > p_prev), we do not
* have a reliable estimate for R_m of [RFC 3448, 6.2] and so
* need to reuse the previous value of X_recv. However, when
* X_recv was 0 (due to early loss), this would kill X down to
* s/t_mbi (i.e. one packet in 64 seconds).
* To avoid such drastic reduction, we approximate X_recv as
* the number of bytes since last feedback.
* This is a safe fallback, since X is bounded above by X_calc.
*/
if (hcrx->ccid3hcrx_x_recv > 0)
break;
/* fall through */
case CCID3_FBACK_PERIODIC:
delta = ktime_us_delta(now, hcrx->ccid3hcrx_tstamp_last_feedback);
if (delta <= 0)
DCCP_BUG("delta (%ld) <= 0", (long)delta);
else
hcrx->ccid3hcrx_x_recv =
scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);
break;
case TFRC_RSTATE_TERM:
DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk);
default:
return;
}
packet = tfrc_rx_hist_find_data_packet(&hcrx->ccid3hcrx_hist);
if (unlikely(packet == NULL)) {
DCCP_WARN("%s(%p), no data packet in history!\n",
dccp_role(sk), sk);
return;
}
ccid3_pr_debug("Interval %ldusec, X_recv=%u, 1/p=%u\n", (long)delta,
hcrx->ccid3hcrx_x_recv, hcrx->ccid3hcrx_pinv);
hcrx->ccid3hcrx_tstamp_last_feedback = now;
hcrx->ccid3hcrx_ccval_last_counter = packet->tfrchrx_ccval;
hcrx->ccid3hcrx_last_counter = dccp_hdr(skb)->dccph_ccval;
hcrx->ccid3hcrx_bytes_recv = 0;
if (hcrx->ccid3hcrx_p == 0)
hcrx->ccid3hcrx_pinv = ~0U; /* see RFC 4342, 8.5 */
else if (hcrx->ccid3hcrx_p > 1000000) {
DCCP_WARN("p (%u) > 100%%\n", hcrx->ccid3hcrx_p);
hcrx->ccid3hcrx_pinv = 1; /* use 100% in this case */
} else
hcrx->ccid3hcrx_pinv = 1000000 / hcrx->ccid3hcrx_p;
dp->dccps_hc_rx_insert_options = 1;
dccp_send_ack(sk);
}
@ -750,165 +760,74 @@ static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
return 0;
}
static int ccid3_hc_rx_detect_loss(struct sock *sk,
struct tfrc_rx_hist_entry *packet)
{
struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
struct tfrc_rx_hist_entry *rx_hist =
tfrc_rx_hist_head(&hcrx->ccid3hcrx_hist);
u64 seqno = packet->tfrchrx_seqno;
u64 tmp_seqno;
int loss = 0;
u8 ccval;
tmp_seqno = hcrx->ccid3hcrx_seqno_nonloss;
if (!rx_hist ||
follows48(packet->tfrchrx_seqno, hcrx->ccid3hcrx_seqno_nonloss)) {
hcrx->ccid3hcrx_seqno_nonloss = seqno;
hcrx->ccid3hcrx_ccval_nonloss = packet->tfrchrx_ccval;
goto detect_out;
}
while (dccp_delta_seqno(hcrx->ccid3hcrx_seqno_nonloss, seqno)
> TFRC_RECV_NUM_LATE_LOSS) {
loss = 1;
dccp_li_update_li(sk,
&hcrx->ccid3hcrx_li_hist,
&hcrx->ccid3hcrx_hist,
hcrx->ccid3hcrx_tstamp_last_feedback,
hcrx->ccid3hcrx_s,
hcrx->ccid3hcrx_bytes_recv,
hcrx->ccid3hcrx_x_recv,
hcrx->ccid3hcrx_seqno_nonloss,
hcrx->ccid3hcrx_ccval_nonloss);
tmp_seqno = hcrx->ccid3hcrx_seqno_nonloss;
dccp_inc_seqno(&tmp_seqno);
hcrx->ccid3hcrx_seqno_nonloss = tmp_seqno;
dccp_inc_seqno(&tmp_seqno);
while (tfrc_rx_hist_find_entry(&hcrx->ccid3hcrx_hist,
tmp_seqno, &ccval)) {
hcrx->ccid3hcrx_seqno_nonloss = tmp_seqno;
hcrx->ccid3hcrx_ccval_nonloss = ccval;
dccp_inc_seqno(&tmp_seqno);
}
}
/* FIXME - this code could be simplified with above while */
/* but works at moment */
if (follows48(packet->tfrchrx_seqno, hcrx->ccid3hcrx_seqno_nonloss)) {
hcrx->ccid3hcrx_seqno_nonloss = seqno;
hcrx->ccid3hcrx_ccval_nonloss = packet->tfrchrx_ccval;
}
detect_out:
tfrc_rx_hist_add_packet(&hcrx->ccid3hcrx_hist,
&hcrx->ccid3hcrx_li_hist, packet,
hcrx->ccid3hcrx_seqno_nonloss);
return loss;
}
static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
const struct dccp_options_received *opt_recv;
struct tfrc_rx_hist_entry *packet;
u32 p_prev, r_sample, rtt_prev;
int loss, payload_size;
ktime_t now;
enum ccid3_fback_type do_feedback = CCID3_FBACK_NONE;
const u32 ndp = dccp_sk(sk)->dccps_options_received.dccpor_ndp;
const bool is_data_packet = dccp_data_packet(skb);
opt_recv = &dccp_sk(sk)->dccps_options_received;
switch (DCCP_SKB_CB(skb)->dccpd_type) {
case DCCP_PKT_ACK:
if (hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)
return;
case DCCP_PKT_DATAACK:
if (opt_recv->dccpor_timestamp_echo == 0)
break;
r_sample = dccp_timestamp() - opt_recv->dccpor_timestamp_echo;
rtt_prev = hcrx->ccid3hcrx_rtt;
r_sample = dccp_sample_rtt(sk, 10 * r_sample);
if (hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)
hcrx->ccid3hcrx_rtt = r_sample;
else
hcrx->ccid3hcrx_rtt = (hcrx->ccid3hcrx_rtt * 9) / 10 +
r_sample / 10;
if (rtt_prev != hcrx->ccid3hcrx_rtt)
ccid3_pr_debug("%s(%p), New RTT=%uus, elapsed time=%u\n",
dccp_role(sk), sk, hcrx->ccid3hcrx_rtt,
opt_recv->dccpor_elapsed_time);
break;
case DCCP_PKT_DATA:
break;
default: /* We're not interested in other packet types, move along */
return;
}
packet = tfrc_rx_hist_entry_new(opt_recv->dccpor_ndp, skb, GFP_ATOMIC);
if (unlikely(packet == NULL)) {
DCCP_WARN("%s(%p), Not enough mem to add rx packet "
"to history, consider it lost!\n", dccp_role(sk), sk);
return;
}
loss = ccid3_hc_rx_detect_loss(sk, packet);
if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK)
return;
payload_size = skb->len - dccp_hdr(skb)->dccph_doff * 4;
ccid3_hc_rx_update_s(hcrx, payload_size);
switch (hcrx->ccid3hcrx_state) {
case TFRC_RSTATE_NO_DATA:
ccid3_pr_debug("%s(%p, state=%s), skb=%p, sending initial "
"feedback\n", dccp_role(sk), sk,
dccp_state_name(sk->sk_state), skb);
ccid3_hc_rx_send_feedback(sk);
if (unlikely(hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)) {
if (is_data_packet) {
const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4;
do_feedback = CCID3_FBACK_INITIAL;
ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA);
return;
case TFRC_RSTATE_DATA:
hcrx->ccid3hcrx_bytes_recv += payload_size;
if (loss)
break;
now = ktime_get_real();
if ((ktime_us_delta(now, hcrx->ccid3hcrx_tstamp_last_ack) -
(s64)hcrx->ccid3hcrx_rtt) >= 0) {
hcrx->ccid3hcrx_tstamp_last_ack = now;
ccid3_hc_rx_send_feedback(sk);
hcrx->ccid3hcrx_s = payload;
/*
* Not necessary to update ccid3hcrx_bytes_recv here,
* since X_recv = 0 for the first feedback packet (cf.
* RFC 3448, 6.3) -- gerrit
*/
}
return;
case TFRC_RSTATE_TERM:
DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk);
return;
goto update_records;
}
/* Dealing with packet loss */
ccid3_pr_debug("%s(%p, state=%s), data loss! Reacting...\n",
dccp_role(sk), sk, dccp_state_name(sk->sk_state));
if (tfrc_rx_hist_duplicate(&hcrx->ccid3hcrx_hist, skb))
return; /* done receiving */
p_prev = hcrx->ccid3hcrx_p;
/* Calculate loss event rate */
if (!list_empty(&hcrx->ccid3hcrx_li_hist)) {
u32 i_mean = dccp_li_hist_calc_i_mean(&hcrx->ccid3hcrx_li_hist);
/* Scaling up by 1000000 as fixed decimal */
if (i_mean != 0)
hcrx->ccid3hcrx_p = 1000000 / i_mean;
} else
DCCP_BUG("empty loss history");
if (hcrx->ccid3hcrx_p > p_prev) {
ccid3_hc_rx_send_feedback(sk);
return;
if (is_data_packet) {
const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4;
/*
* Update moving-average of s and the sum of received payload bytes
*/
hcrx->ccid3hcrx_s = tfrc_ewma(hcrx->ccid3hcrx_s, payload, 9);
hcrx->ccid3hcrx_bytes_recv += payload;
}
/*
* Handle pending losses and otherwise check for new loss
*/
if (tfrc_rx_hist_new_loss_indicated(&hcrx->ccid3hcrx_hist, skb, ndp))
goto update_records;
/*
* Handle data packets: RTT sampling and monitoring p
*/
if (unlikely(!is_data_packet))
goto update_records;
if (list_empty(&hcrx->ccid3hcrx_li_hist)) { /* no loss so far: p = 0 */
const u32 sample = tfrc_rx_hist_sample_rtt(&hcrx->ccid3hcrx_hist, skb);
/*
* Empty loss history: no loss so far, hence p stays 0.
* Sample RTT values, since an RTT estimate is required for the
* computation of p when the first loss occurs; RFC 3448, 6.3.1.
*/
if (sample != 0)
hcrx->ccid3hcrx_rtt = tfrc_ewma(hcrx->ccid3hcrx_rtt, sample, 9);
}
/*
* Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3
*/
if (SUB16(dccp_hdr(skb)->dccph_ccval, hcrx->ccid3hcrx_last_counter) > 3)
do_feedback = CCID3_FBACK_PERIODIC;
update_records:
tfrc_rx_hist_add_packet(&hcrx->ccid3hcrx_hist, skb, ndp);
if (do_feedback)
ccid3_hc_rx_send_feedback(sk, skb, do_feedback);
}
static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
@ -918,11 +837,8 @@ static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
ccid3_pr_debug("entry\n");
hcrx->ccid3hcrx_state = TFRC_RSTATE_NO_DATA;
INIT_LIST_HEAD(&hcrx->ccid3hcrx_hist);
INIT_LIST_HEAD(&hcrx->ccid3hcrx_li_hist);
hcrx->ccid3hcrx_tstamp_last_feedback =
hcrx->ccid3hcrx_tstamp_last_ack = ktime_get_real();
return 0;
return tfrc_rx_hist_alloc(&hcrx->ccid3hcrx_hist);
}
static void ccid3_hc_rx_exit(struct sock *sk)

14
net/dccp/ccids/ccid3.h
View File

@ -1,7 +1,8 @@
/*
* net/dccp/ccids/ccid3.h
*
* Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
* Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
* Copyright (c) 2007 The University of Aberdeen, Scotland, UK
*
* An implementation of the DCCP protocol
*
@ -135,9 +136,7 @@ enum ccid3_hc_rx_states {
* @ccid3hcrx_x_recv - Receiver estimate of send rate (RFC 3448 4.3)
* @ccid3hcrx_rtt - Receiver estimate of rtt (non-standard)
* @ccid3hcrx_p - current loss event rate (RFC 3448 5.4)
* @ccid3hcrx_seqno_nonloss - Last received non-loss sequence number
* @ccid3hcrx_ccval_nonloss - Last received non-loss Window CCVal
* @ccid3hcrx_ccval_last_counter - Tracks window counter (RFC 4342, 8.1)
* @ccid3hcrx_last_counter - Tracks window counter (RFC 4342, 8.1)
* @ccid3hcrx_state - receiver state, one of %ccid3_hc_rx_states
* @ccid3hcrx_bytes_recv - Total sum of DCCP payload bytes
* @ccid3hcrx_tstamp_last_feedback - Time at which last feedback was sent
@ -152,14 +151,11 @@ struct ccid3_hc_rx_sock {
#define ccid3hcrx_x_recv ccid3hcrx_tfrc.tfrcrx_x_recv
#define ccid3hcrx_rtt ccid3hcrx_tfrc.tfrcrx_rtt
#define ccid3hcrx_p ccid3hcrx_tfrc.tfrcrx_p
u64 ccid3hcrx_seqno_nonloss:48,
ccid3hcrx_ccval_nonloss:4,
ccid3hcrx_ccval_last_counter:4;
u8 ccid3hcrx_last_counter:4;
enum ccid3_hc_rx_states ccid3hcrx_state:8;
u32 ccid3hcrx_bytes_recv;
ktime_t ccid3hcrx_tstamp_last_feedback;
ktime_t ccid3hcrx_tstamp_last_ack;
struct list_head ccid3hcrx_hist;
struct tfrc_rx_hist ccid3hcrx_hist;
struct list_head ccid3hcrx_li_hist;
u16 ccid3hcrx_s;
u32 ccid3hcrx_pinv;

13
net/dccp/ccids/lib/loss_interval.c
View File

@ -129,6 +129,13 @@ static u32 dccp_li_calc_first_li(struct sock *sk,
u16 s, u32 bytes_recv,
u32 previous_x_recv)
{
/*
* FIXME:
* Will be rewritten in the upcoming new loss intervals code.
* Has to be commented ou because it relies on the old rx history
* data structures
*/
#if 0
struct tfrc_rx_hist_entry *entry, *next, *tail = NULL;
u32 x_recv, p;
suseconds_t rtt, delta;
@ -216,10 +223,10 @@ found:
dccp_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
"loss rate=%u\n", dccp_role(sk), sk, x_recv, p);
if (p == 0)
return ~0;
else
if (p != 0)
return 1000000 / p;
#endif
return ~0;
}
void dccp_li_update_li(struct sock *sk,

306
net/dccp/ccids/lib/packet_history.c
View File

@ -36,7 +36,9 @@
*/
#include <linux/string.h>
#include <linux/slab.h>
#include "packet_history.h"
#include "../../dccp.h"
/**
* tfrc_tx_hist_entry - Simple singly-linked TX history list
@ -111,19 +113,34 @@ u32 tfrc_tx_hist_rtt(struct tfrc_tx_hist_entry *head, const u64 seqno,
}
EXPORT_SYMBOL_GPL(tfrc_tx_hist_rtt);
/**
* tfrc_rx_hist_index - index to reach n-th entry after loss_start
*/
static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n)
{
return (h->loss_start + n) & TFRC_NDUPACK;
}
/**
* tfrc_rx_hist_last_rcv - entry with highest-received-seqno so far
*/
static inline struct tfrc_rx_hist_entry *
tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h)
{
return h->ring[tfrc_rx_hist_index(h, h->loss_count)];
}
/*
* Receiver History Routines
*/
static struct kmem_cache *tfrc_rx_hist_slab;
struct tfrc_rx_hist_entry *tfrc_rx_hist_entry_new(const u32 ndp,
void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,
const struct sk_buff *skb,
const gfp_t prio)
const u32 ndp)
{
struct tfrc_rx_hist_entry *entry = kmem_cache_alloc(tfrc_rx_hist_slab,
prio);
if (entry != NULL) {
struct tfrc_rx_hist_entry *entry = tfrc_rx_hist_last_rcv(h);
const struct dccp_hdr *dh = dccp_hdr(skb);
entry->tfrchrx_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
@ -132,134 +149,179 @@ struct tfrc_rx_hist_entry *tfrc_rx_hist_entry_new(const u32 ndp,
entry->tfrchrx_ndp = ndp;
entry->tfrchrx_tstamp = ktime_get_real();
}
return entry;
}
EXPORT_SYMBOL_GPL(tfrc_rx_hist_entry_new);
EXPORT_SYMBOL_GPL(tfrc_rx_hist_add_packet);
static inline void tfrc_rx_hist_entry_delete(struct tfrc_rx_hist_entry *entry)
{
kmem_cache_free(tfrc_rx_hist_slab, entry);
}
int tfrc_rx_hist_find_entry(const struct list_head *list, const u64 seq,
u8 *ccval)
{
struct tfrc_rx_hist_entry *packet = NULL, *entry;
list_for_each_entry(entry, list, tfrchrx_node)
if (entry->tfrchrx_seqno == seq) {
packet = entry;
break;
}
if (packet)
*ccval = packet->tfrchrx_ccval;
return packet != NULL;
}
EXPORT_SYMBOL_GPL(tfrc_rx_hist_find_entry);
struct tfrc_rx_hist_entry *
tfrc_rx_hist_find_data_packet(const struct list_head *list)
{
struct tfrc_rx_hist_entry *entry, *packet = NULL;
list_for_each_entry(entry, list, tfrchrx_node)
if (entry->tfrchrx_type == DCCP_PKT_DATA ||
entry->tfrchrx_type == DCCP_PKT_DATAACK) {
packet = entry;
break;
}
return packet;
}
EXPORT_SYMBOL_GPL(tfrc_rx_hist_find_data_packet);
void tfrc_rx_hist_add_packet(struct list_head *rx_list,
struct list_head *li_list,
struct tfrc_rx_hist_entry *packet,
u64 nonloss_seqno)
{
struct tfrc_rx_hist_entry *entry, *next;
u8 num_later = 0;
list_add(&packet->tfrchrx_node, rx_list);
num_later = TFRC_RECV_NUM_LATE_LOSS + 1;
if (!list_empty(li_list)) {
list_for_each_entry_safe(entry, next, rx_list, tfrchrx_node) {
if (num_later == 0) {
if (after48(nonloss_seqno,
entry->tfrchrx_seqno)) {
list_del_init(&entry->tfrchrx_node);
tfrc_rx_hist_entry_delete(entry);
}
} else if (tfrc_rx_hist_entry_data_packet(entry))
--num_later;
}
} else {
int step = 0;
u8 win_count = 0; /* Not needed, but lets shut up gcc */
int tmp;
/*
* We have no loss interval history so we need at least one
* rtt:s of data packets to approximate rtt.
/**
* tfrc_rx_hist_entry - return the n-th history entry after loss_start
*/
list_for_each_entry_safe(entry, next, rx_list, tfrchrx_node) {
if (num_later == 0) {
switch (step) {
case 0:
step = 1;
/* OK, find next data packet */
num_later = 1;
break;
case 1:
step = 2;
/* OK, find next data packet */
num_later = 1;
win_count = entry->tfrchrx_ccval;
break;
case 2:
tmp = win_count - entry->tfrchrx_ccval;
if (tmp < 0)
tmp += TFRC_WIN_COUNT_LIMIT;
if (tmp > TFRC_WIN_COUNT_PER_RTT + 1) {
/*
* We have found a packet older
* than one rtt remove the rest
*/
step = 3;
} else /* OK, find next data packet */
num_later = 1;
break;
case 3:
list_del_init(&entry->tfrchrx_node);
tfrc_rx_hist_entry_delete(entry);
break;
}
} else if (tfrc_rx_hist_entry_data_packet(entry))
--num_later;
}
}
}
EXPORT_SYMBOL_GPL(tfrc_rx_hist_add_packet);
void tfrc_rx_hist_purge(struct list_head *list)
static inline struct tfrc_rx_hist_entry *
tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n)
{
struct tfrc_rx_hist_entry *entry, *next;
list_for_each_entry_safe(entry, next, list, tfrchrx_node) {
list_del_init(&entry->tfrchrx_node);
tfrc_rx_hist_entry_delete(entry);
}
return h->ring[tfrc_rx_hist_index(h, n)];
}
/**
* tfrc_rx_hist_loss_prev - entry with highest-received-seqno before loss was detected
*/
static inline struct tfrc_rx_hist_entry *
tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h)
{
return h->ring[h->loss_start];
}
/* has the packet contained in skb been seen before? */
int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb)
{
const u64 seq = DCCP_SKB_CB(skb)->dccpd_seq;
int i;
if (dccp_delta_seqno(tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, seq) <= 0)
return 1;
for (i = 1; i <= h->loss_count; i++)
if (tfrc_rx_hist_entry(h, i)->tfrchrx_seqno == seq)
return 1;
return 0;
}
EXPORT_SYMBOL_GPL(tfrc_rx_hist_duplicate);
/* initialise loss detection and disable RTT sampling */
static inline void tfrc_rx_hist_loss_indicated(struct tfrc_rx_hist *h)
{
h->loss_count = 1;
}
/* indicate whether previously a packet was detected missing */
static inline int tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
{
return h->loss_count;
}
/* any data packets missing between last reception and skb ? */
int tfrc_rx_hist_new_loss_indicated(struct tfrc_rx_hist *h,
const struct sk_buff *skb, u32 ndp)
{
int delta = dccp_delta_seqno(tfrc_rx_hist_last_rcv(h)->tfrchrx_seqno,
DCCP_SKB_CB(skb)->dccpd_seq);
if (delta > 1 && ndp < delta)
tfrc_rx_hist_loss_indicated(h);
return tfrc_rx_hist_loss_pending(h);
}
EXPORT_SYMBOL_GPL(tfrc_rx_hist_new_loss_indicated);
int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h)
{
int i;
for (i = 0; i <= TFRC_NDUPACK; i++) {
h->ring[i] = kmem_cache_alloc(tfrc_rx_hist_slab, GFP_ATOMIC);
if (h->ring[i] == NULL)
goto out_free;
}
h->loss_count = h->loss_start = 0;
return 0;
out_free:
while (i-- != 0) {
kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]);
h->ring[i] = NULL;
}
return -ENOBUFS;
}
EXPORT_SYMBOL_GPL(tfrc_rx_hist_alloc);
void tfrc_rx_hist_purge(struct tfrc_rx_hist *h)
{
int i;
for (i = 0; i <= TFRC_NDUPACK; ++i)
if (h->ring[i] != NULL) {
kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]);
h->ring[i] = NULL;
}
}
EXPORT_SYMBOL_GPL(tfrc_rx_hist_purge);
/**
* tfrc_rx_hist_rtt_last_s - reference entry to compute RTT samples against
*/
static inline struct tfrc_rx_hist_entry *
tfrc_rx_hist_rtt_last_s(const struct tfrc_rx_hist *h)
{
return h->ring[0];
}
/**
* tfrc_rx_hist_rtt_prev_s: previously suitable (wrt rtt_last_s) RTT-sampling entry
*/
static inline struct tfrc_rx_hist_entry *
tfrc_rx_hist_rtt_prev_s(const struct tfrc_rx_hist *h)
{
return h->ring[h->rtt_sample_prev];
}
/**
* tfrc_rx_hist_sample_rtt - Sample RTT from timestamp / CCVal
* Based on ideas presented in RFC 4342, 8.1. Returns 0 if it was not able
* to compute a sample with given data - calling function should check this.
*/
u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h, const struct sk_buff *skb)
{
u32 sample = 0,
delta_v = SUB16(dccp_hdr(skb)->dccph_ccval,
tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval);
if (delta_v < 1 || delta_v > 4) { /* unsuitable CCVal delta */
if (h->rtt_sample_prev == 2) { /* previous candidate stored */
sample = SUB16(tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_ccval,
tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval);
if (sample)
sample = 4 / sample *
ktime_us_delta(tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_tstamp,
tfrc_rx_hist_rtt_last_s(h)->tfrchrx_tstamp);
else /*
* FIXME: This condition is in principle not
* possible but occurs when CCID is used for
* two-way data traffic. I have tried to trace
* it, but the cause does not seem to be here.
*/
DCCP_BUG("please report to dccp@vger.kernel.org"
" => prev = %u, last = %u",
tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_ccval,
tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval);
} else if (delta_v < 1) {
h->rtt_sample_prev = 1;
goto keep_ref_for_next_time;
}
} else if (delta_v == 4) /* optimal match */
sample = ktime_to_us(net_timedelta(tfrc_rx_hist_rtt_last_s(h)->tfrchrx_tstamp));
else { /* suboptimal match */
h->rtt_sample_prev = 2;
goto keep_ref_for_next_time;
}
if (unlikely(sample > DCCP_SANE_RTT_MAX)) {
DCCP_WARN("RTT sample %u too large, using max\n", sample);
sample = DCCP_SANE_RTT_MAX;
}
h->rtt_sample_prev = 0; /* use current entry as next reference */
keep_ref_for_next_time:
return sample;
}
EXPORT_SYMBOL_GPL(tfrc_rx_hist_sample_rtt);
__init int packet_history_init(void)
{
tfrc_tx_hist_slab = kmem_cache_create("tfrc_tx_hist",

83
net/dccp/ccids/lib/packet_history.h
View File

@ -37,15 +37,9 @@
#define _DCCP_PKT_HIST_
#include <linux/ktime.h>
#include <linux/list.h>
#include <linux/slab.h>
#include "tfrc.h"
#include <linux/types.h>
/* Number of later packets received before one is considered lost */
#define TFRC_RECV_NUM_LATE_LOSS 3
#define TFRC_WIN_COUNT_PER_RTT 4
#define TFRC_WIN_COUNT_LIMIT 16
struct sk_buff;
struct tfrc_tx_hist_entry;
@ -54,11 +48,20 @@ extern void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp);
extern u32 tfrc_tx_hist_rtt(struct tfrc_tx_hist_entry *head,
const u64 seqno, const ktime_t now);
/*
* Receiver History data structures and declarations
/* Subtraction a-b modulo-16, respects circular wrap-around */
#define SUB16(a, b) (((a) + 16 - (b)) & 0xF)
/* Number of packets to wait after a missing packet (RFC 4342, 6.1) */
#define TFRC_NDUPACK 3
/**
* tfrc_rx_hist_entry - Store information about a single received packet
* @tfrchrx_seqno: DCCP packet sequence number
* @tfrchrx_ccval: window counter value of packet (RFC 4342, 8.1)
* @tfrchrx_ndp: the NDP count (if any) of the packet
* @tfrchrx_tstamp: actual receive time of packet
*/
struct tfrc_rx_hist_entry {
struct list_head tfrchrx_node;
u64 tfrchrx_seqno:48,
tfrchrx_ccval:4,
tfrchrx_type:4;
@ -66,42 +69,30 @@ struct tfrc_rx_hist_entry {
ktime_t tfrchrx_tstamp;
};
extern struct tfrc_rx_hist_entry *
tfrc_rx_hist_entry_new(const u32 ndp,
const struct sk_buff *skb,
const gfp_t prio);
/**
* tfrc_rx_hist - RX history structure for TFRC-based protocols
*
* @ring: Packet history for RTT sampling and loss detection
* @loss_count: Number of entries in circular history
* @loss_start: Movable index (for loss detection)
* @rtt_sample_prev: Used during RTT sampling, points to candidate entry
*/
struct tfrc_rx_hist {
struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1];
u8 loss_count:2,
loss_start:2;
#define rtt_sample_prev loss_start
};
static inline struct tfrc_rx_hist_entry *
tfrc_rx_hist_head(struct list_head *list)
{
struct tfrc_rx_hist_entry *head = NULL;
extern void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,
const struct sk_buff *skb, const u32 ndp);
if (!list_empty(list))
head = list_entry(list->next, struct tfrc_rx_hist_entry,
tfrchrx_node);
return head;
}
extern int tfrc_rx_hist_find_entry(const struct list_head *list, const u64 seq,
u8 *ccval);
extern struct tfrc_rx_hist_entry *
tfrc_rx_hist_find_data_packet(const struct list_head *list);
extern void tfrc_rx_hist_add_packet(struct list_head *rx_list,
struct list_head *li_list,
struct tfrc_rx_hist_entry *packet,
u64 nonloss_seqno);
extern void tfrc_rx_hist_purge(struct list_head *list);
static inline int
tfrc_rx_hist_entry_data_packet(const struct tfrc_rx_hist_entry *entry)
{
return entry->tfrchrx_type == DCCP_PKT_DATA ||
entry->tfrchrx_type == DCCP_PKT_DATAACK;
}
extern u64 tfrc_rx_hist_detect_loss(struct list_head *rx_list,
struct list_head *li_list, u8 *win_loss);
extern int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb);
extern int tfrc_rx_hist_new_loss_indicated(struct tfrc_rx_hist *h,
const struct sk_buff *skb, u32 ndp);
extern u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h,
const struct sk_buff *skb);
extern int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h);
extern void tfrc_rx_hist_purge(struct tfrc_rx_hist *h);
#endif /* _DCCP_PKT_HIST_ */