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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
Download Patch File Download Diff File Expand all files Collapse all files

292
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);
hcrx->ccid3hcrx_x_recv =
scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);
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);
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);
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);
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)