In addition, it makes two corrections too the code:
1. The receiver of a half-connection does not set window counter values;
only the sender sets window counters [RFC 4342, sections 5 and 8.1].
2. The computation of X_recv does currently not conform to TFRC/RFC 3448,
since this specification requires that X_recv be computed over the last
R_m seconds (sec. 6.2). The patch tackles this problem as it
- explicitly distinguishes the types of feedback (using an enum);
- uses previous value of X_recv when sending feedback due to a parameter
change;
- makes all state changes local to ccid3_hc_tx_packet_recv;
- assigns feedback type according to incident (previously only used flag
`do_feedback').
Further and detailed information is at
http://www.erg.abdn.ac.uk/users/gerrit/dccp/notes/ccid3_packet_reception/#8._Computing_X_recv_
Signed-off-by: Gerrit Renker <[EMAIL PROTECTED]>
Signed-off-by: Ian McDonald <[EMAIL PROTECTED]>
---
net/dccp/ccids/ccid3.c | 289 ++++++++++++++----------------------------------
net/dccp/ccids/ccid3.h | 38 ++++---
2 files changed, 103 insertions(+), 224 deletions(-)
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index 51fd07b..9ced34c 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -1,6 +1,7 @@
/*
* net/dccp/ccids/ccid3.c
*
+ * Copyright (c) 2007 The University of Aberdeen, Scotland, UK
* Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
* Copyright (c) 2005-7 Ian McDonald <[EMAIL PROTECTED]>
*
@@ -50,7 +51,6 @@ static int ccid3_debug;
#endif
DECLARE_TFRC_TX_CACHE(ccid3_tx_hist);
-static struct dccp_rx_hist *ccid3_rx_hist;
/*
* Transmitter Half-Connection Routines
@@ -679,52 +679,53 @@ static inline void ccid3_hc_rx_update_s(struct
ccid3_hc_rx_sock *hcrx, int len)
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, 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 dccp_rx_hist_entry *packet;
- ktime_t now;
- suseconds_t delta;
-
- ccid3_pr_debug("%s(%p) - entry \n", dccp_role(sk), sk);
+ ktime_t now = ktime_get_real();
+ s64 delta = 0;
- now = ktime_get_real();
+ if (unlikely(hcrx->ccid3hcrx_state == TFRC_RSTATE_TERM))
+ return;
- switch (hcrx->ccid3hcrx_state) {
- case TFRC_RSTATE_NO_DATA:
+ switch (fbtype) {
+ case 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 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 FBACK_PERIODIC:
+ delta = ktime_us_delta(now, hcrx->ccid3hcrx_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);
- return;
- }
-
- packet = dccp_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);
+ default:
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->dccphrx_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;
+ hcrx->ccid3hcrx_last_feedback = now;
+ hcrx->ccid3hcrx_last_counter = dccp_hdr(skb)->dccph_ccval;
+ hcrx->ccid3hcrx_bytes_recv = 0;
dp->dccps_hc_rx_insert_options = 1;
dccp_send_ack(sk);
@@ -739,7 +740,6 @@ static int ccid3_hc_rx_insert_options(struct sock *sk,
struct sk_buff *skb)
return 0;
hcrx = ccid3_hc_rx_sk(sk);
- DCCP_SKB_CB(skb)->dccpd_ccval = hcrx->ccid3hcrx_ccval_last_counter;
if (dccp_packet_without_ack(skb))
return 0;
@@ -747,8 +747,7 @@ static int ccid3_hc_rx_insert_options(struct sock *sk,
struct sk_buff *skb)
x_recv = htonl(hcrx->ccid3hcrx_x_recv);
pinv = htonl(hcrx->ccid3hcrx_pinv);
- if (dccp_insert_option_timestamp(sk, skb) ||
- dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE,
+ if (dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE,
&pinv, sizeof(pinv)) ||
dccp_insert_option(sk, skb, TFRC_OPT_RECEIVE_RATE,
&x_recv, sizeof(x_recv)))
@@ -757,166 +756,62 @@ 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 dccp_rx_hist_entry *packet)
+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);
- struct dccp_rx_hist_entry *rx_hist =
- dccp_rx_hist_head(&hcrx->ccid3hcrx_hist);
- u64 seqno = packet->dccphrx_seqno;
- u64 tmp_seqno;
- int loss = 0;
- u8 ccval;
-
-
- tmp_seqno = hcrx->ccid3hcrx_seqno_nonloss;
-
- if (!rx_hist ||
- follows48(packet->dccphrx_seqno, hcrx->ccid3hcrx_seqno_nonloss)) {
- hcrx->ccid3hcrx_seqno_nonloss = seqno;
- hcrx->ccid3hcrx_ccval_nonloss = packet->dccphrx_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 (dccp_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);
+ enum ccid3_fback_type do_feedback = FBACK_NONE;
+ u32 sample, ndp = dccp_sk(sk)->dccps_options_received.dccpor_ndp,
+ payload_size = skb->len - dccp_hdr(skb)->dccph_doff * 4;
+ u8 is_data_packet = dccp_data_packet(skb);
+
+ if (unlikely(hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)) {
+ if (is_data_packet) {
+ do_feedback = FBACK_INITIAL;
+ ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA);
+ ccid3_hc_rx_update_s(hcrx, payload_size);
}
+ goto update_records;
}
- /* FIXME - this code could be simplified with above while */
- /* but works at moment */
- if (follows48(packet->dccphrx_seqno, hcrx->ccid3hcrx_seqno_nonloss)) {
- hcrx->ccid3hcrx_seqno_nonloss = seqno;
- hcrx->ccid3hcrx_ccval_nonloss = packet->dccphrx_ccval;
- }
-
-detect_out:
- dccp_rx_hist_add_packet(ccid3_rx_hist, &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 dccp_rx_hist_entry *packet;
- u32 p_prev, r_sample, rtt_prev;
- int loss, payload_size;
- ktime_t now;
-
- 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 (tfrc_rx_duplicate(&hcrx->ccid3hcrx_hist, skb))
+ goto done_receiving;
- 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 = dccp_rx_hist_entry_new(ccid3_rx_hist, 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;
+ if (is_data_packet) {
+ ccid3_hc_rx_update_s(hcrx, payload_size);
+ hcrx->ccid3hcrx_bytes_recv += payload_size;
}
- loss = ccid3_hc_rx_detect_loss(sk, packet);
+ /*
+ * Handle pending losses and otherwise check for new loss
+ */
+ if (tfrc_rx_new_loss_indicated(&hcrx->ccid3hcrx_hist, skb, ndp))
+ goto update_records;
- if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK)
- return;
+ /*
+ * Handle data packets: RTT sampling and monitoring p
+ */
+ if (unlikely(!is_data_packet))
+ goto update_records;
- payload_size = skb->len - dccp_hdr(skb)->dccph_doff * 4;
- ccid3_hc_rx_update_s(hcrx, payload_size);
+ if (list_empty(&hcrx->ccid3hcrx_li_hist)) { /* no loss so far: p = 0 */
- 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;
+ sample = tfrc_rx_sample_rtt(&hcrx->ccid3hcrx_hist, skb);
+ if (sample != 0)
+ hcrx->ccid3hcrx_rtt =
+ tfrc_ewma(hcrx->ccid3hcrx_rtt, sample, 9);
- 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);
- }
- return;
- case TFRC_RSTATE_TERM:
- DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk);
- return;
}
- /* 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));
+ /* 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 = FBACK_PERIODIC;
- p_prev = hcrx->ccid3hcrx_p;
+update_records:
+ tfrc_rx_hist_update(&hcrx->ccid3hcrx_hist, skb, ndp);
- /* 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;
- }
+done_receiving:
+ if (do_feedback)
+ ccid3_hc_rx_send_feedback(sk, skb, do_feedback);
}
static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
@@ -926,10 +821,9 @@ 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);
+ if (tfrc_rx_hist_init(&hcrx->ccid3hcrx_hist))
+ return 1;
INIT_LIST_HEAD(&hcrx->ccid3hcrx_li_hist);
- hcrx->ccid3hcrx_tstamp_last_feedback =
- hcrx->ccid3hcrx_tstamp_last_ack = ktime_get_real();
return 0;
}
@@ -939,8 +833,7 @@ static void ccid3_hc_rx_exit(struct sock *sk)
ccid3_hc_rx_set_state(sk, TFRC_RSTATE_TERM);
- /* Empty packet history */
- dccp_rx_hist_purge(ccid3_rx_hist, &hcrx->ccid3hcrx_hist);
+ tfrc_rx_hist_cleanup(&hcrx->ccid3hcrx_hist);
/* Empty loss interval history */
dccp_li_hist_purge(&hcrx->ccid3hcrx_li_hist);
@@ -1019,25 +912,14 @@ static __init int ccid3_module_init(void)
{
int rc = -ENOBUFS;
- ccid3_rx_hist = dccp_rx_hist_new("ccid3");
- if (ccid3_rx_hist == NULL)
- goto out;
-
if (tfrc_tx_cache_init(&ccid3_tx_hist, "ccid3"))
- goto out_free_rx;
+ goto out;
rc = ccid_register(&ccid3);
if (rc != 0)
- goto out_free_tx;
+ tfrc_tx_cache_cleanup(ccid3_tx_hist);
out:
return rc;
-
-out_free_tx:
- tfrc_tx_cache_cleanup(ccid3_tx_hist);
-out_free_rx:
- dccp_rx_hist_delete(ccid3_rx_hist);
- ccid3_rx_hist = NULL;
- goto out;
}
module_init(ccid3_module_init);
@@ -1047,11 +929,6 @@ static __exit void ccid3_module_exit(void)
if (ccid3_tx_hist != NULL)
tfrc_tx_cache_cleanup(ccid3_tx_hist);
-
- if (ccid3_rx_hist != NULL) {
- dccp_rx_hist_delete(ccid3_rx_hist);
- ccid3_rx_hist = NULL;
- }
}
module_exit(ccid3_module_exit);
diff --git a/net/dccp/ccids/ccid3.h b/net/dccp/ccids/ccid3.h
index fd363f0..e5202f1 100644
--- a/net/dccp/ccids/ccid3.h
+++ b/net/dccp/ccids/ccid3.h
@@ -1,7 +1,10 @@
+#ifndef _DCCP_CCID3_H_
+#define _DCCP_CCID3_H_
/*
* net/dccp/ccids/ccid3.h
*
- * Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
+ * Copyright (c) 2007 The University of Aberdeen, Scotland, UK
+ * Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
*
* An implementation of the DCCP protocol
*
@@ -33,9 +36,6 @@
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
-#ifndef _DCCP_CCID3_H_
-#define _DCCP_CCID3_H_
-
#include <linux/ktime.h>
#include <linux/list.h>
#include <linux/types.h>
@@ -123,26 +123,31 @@ static inline struct ccid3_hc_tx_sock
*ccid3_hc_tx_sk(const struct sock *sk)
return hctx;
}
-/* TFRC receiver states */
+/* CCID3 receiver states */
enum ccid3_hc_rx_states {
TFRC_RSTATE_NO_DATA = 1,
TFRC_RSTATE_DATA,
TFRC_RSTATE_TERM = 127,
};
+/* CCID3 feedback types */
+enum ccid3_fback_type {
+ FBACK_NONE = 0,
+ FBACK_INITIAL,
+ FBACK_PERIODIC,
+ FBACK_PARAM_CHANGE
+};
+
/** struct ccid3_hc_rx_sock - CCID3 receiver half-connection socket
*
* @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_state - receiver state, one of %ccid3_hc_rx_states
+ * @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
- * @ccid3hcrx_tstamp_last_ack - Time at which last feedback was sent
- * @ccid3hcrx_hist - Packet history
+ * @ccid3hcrx_last_feedback - Time at which last feedback was sent
+ * @ccid3hcrx_hist - Packet history, exported by TFRC module
* @ccid3hcrx_li_hist - Loss Interval History
* @ccid3hcrx_s - Received packet size in bytes
* @ccid3hcrx_pinv - Inverse of Loss Event Rate (RFC 4342, sec. 8.5)
@@ -152,14 +157,11 @@ 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;
+ ktime_t ccid3hcrx_last_feedback;
+ struct tfrc_rx_hist ccid3hcrx_hist;
struct list_head ccid3hcrx_li_hist;
u16 ccid3hcrx_s;
u32 ccid3hcrx_pinv;
--
1.5.2.2.238.g7cbf2f2-dirty
-
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