/*
* 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 <ian.mcdonald@jandi.co.nz>
*
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
-#include "../ccid.h"
#include "../dccp.h"
-#include "lib/packet_history.h"
-#include "lib/loss_interval.h"
-#include "lib/tfrc.h"
#include "ccid3.h"
#include <asm/unaligned.h>
#define ccid3_pr_debug(format, a...)
#endif
-static struct dccp_tx_hist *ccid3_tx_hist;
-static struct dccp_rx_hist *ccid3_rx_hist;
-
/*
* Transmitter Half-Connection Routines
*/
}
/*
- * Compute the initial sending rate X_init according to RFC 3390:
- * w_init = min(4 * MSS, max(2 * MSS, 4380 bytes))
- * X_init = w_init / RTT
+ * Compute the initial sending rate X_init in the manner of RFC 3390:
+ *
+ * X_init = min(4 * s, max(2 * s, 4380 bytes)) / RTT
+ *
+ * Note that RFC 3390 uses MSS, RFC 4342 refers to RFC 3390, and rfc3448bis
+ * (rev-02) clarifies the use of RFC 3390 with regard to the above formula.
* For consistency with other parts of the code, X_init is scaled by 2^6.
*/
static inline u64 rfc3390_initial_rate(struct sock *sk)
{
- const struct dccp_sock *dp = dccp_sk(sk);
- const __u32 w_init = min(4 * dp->dccps_mss_cache,
- max(2 * dp->dccps_mss_cache, 4380U));
+ const struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
+ const __u32 w_init = clamp_t(__u32, 4380U,
+ 2 * hctx->ccid3hctx_s, 4 * hctx->ccid3hctx_s);
- return scaled_div(w_init << 6, ccid3_hc_tx_sk(sk)->ccid3hctx_rtt);
+ return scaled_div(w_init << 6, hctx->ccid3hctx_rtt);
}
/*
* Recalculate t_ipi and delta (should be called whenever X changes)
*/
-static inline void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hctx)
+static void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hctx)
{
/* Calculate new t_ipi = s / X_inst (X_inst is in 64 * bytes/second) */
hctx->ccid3hctx_t_ipi = scaled_div32(((u64)hctx->ccid3hctx_s) << 6,
}
+static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hctx, ktime_t now)
+{
+ u32 delta = ktime_us_delta(now, hctx->ccid3hctx_t_last_win_count);
+
+ return delta / hctx->ccid3hctx_rtt;
+}
+
/**
* ccid3_hc_tx_update_x - Update allowed sending rate X
* @stamp: most recent time if available - can be left NULL.
*
*/
static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp)
-
{
struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
__u64 min_rate = 2 * hctx->ccid3hctx_x_recv;
const __u64 old_x = hctx->ccid3hctx_x;
- ktime_t now = stamp? *stamp : ktime_get_real();
+ ktime_t now = stamp ? *stamp : ktime_get_real();
/*
* Handle IDLE periods: do not reduce below RFC3390 initial sending rate
- * when idling [RFC 4342, 5.1]. See also draft-ietf-dccp-rfc3448bis.
+ * when idling [RFC 4342, 5.1]. Definition of idling is from rfc3448bis:
+ * a sender is idle if it has not sent anything over a 2-RTT-period.
* For consistency with X and X_recv, min_rate is also scaled by 2^6.
*/
- if (unlikely(hctx->ccid3hctx_idle)) {
+ if (ccid3_hc_tx_idle_rtt(hctx, now) >= 2) {
min_rate = rfc3390_initial_rate(sk);
min_rate = max(min_rate, 2 * hctx->ccid3hctx_x_recv);
}
} else if (ktime_us_delta(now, hctx->ccid3hctx_t_ld)
- (s64)hctx->ccid3hctx_rtt >= 0) {
- hctx->ccid3hctx_x =
- max(min(2 * hctx->ccid3hctx_x, min_rate),
+ hctx->ccid3hctx_x = min(2 * hctx->ccid3hctx_x, min_rate);
+ hctx->ccid3hctx_x = max(hctx->ccid3hctx_x,
scaled_div(((__u64)hctx->ccid3hctx_s) << 6,
hctx->ccid3hctx_rtt));
hctx->ccid3hctx_t_ld = now;
{
const u16 old_s = hctx->ccid3hctx_s;
- hctx->ccid3hctx_s = old_s == 0 ? len : (9 * old_s + len) / 10;
+ hctx->ccid3hctx_s = tfrc_ewma(hctx->ccid3hctx_s, len, 9);
if (hctx->ccid3hctx_s != old_s)
ccid3_update_send_interval(hctx);
/*
* Update Window Counter using the algorithm from [RFC 4342, 8.1].
- * The algorithm is not applicable if RTT < 4 microseconds.
+ * As elsewhere, RTT > 0 is assumed by using dccp_sample_rtt().
*/
static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hctx,
ktime_t now)
{
- u32 quarter_rtts;
-
- if (unlikely(hctx->ccid3hctx_rtt < 4)) /* avoid divide-by-zero */
- return;
-
- quarter_rtts = ktime_us_delta(now, hctx->ccid3hctx_t_last_win_count);
- quarter_rtts /= hctx->ccid3hctx_rtt / 4;
+ u32 delta = ktime_us_delta(now, hctx->ccid3hctx_t_last_win_count),
+ quarter_rtts = (4 * delta) / hctx->ccid3hctx_rtt;
if (quarter_rtts > 0) {
hctx->ccid3hctx_t_last_win_count = now;
- hctx->ccid3hctx_last_win_count += min_t(u32, quarter_rtts, 5);
+ hctx->ccid3hctx_last_win_count += min(quarter_rtts, 5U);
hctx->ccid3hctx_last_win_count &= 0xF; /* mod 16 */
}
}
ccid3_pr_debug("%s(%p, state=%s) - entry \n", dccp_role(sk), sk,
ccid3_tx_state_name(hctx->ccid3hctx_state));
- hctx->ccid3hctx_idle = 1;
+ if (hctx->ccid3hctx_state == TFRC_SSTATE_FBACK)
+ ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
+ else if (hctx->ccid3hctx_state != TFRC_SSTATE_NO_FBACK)
+ goto out;
- switch (hctx->ccid3hctx_state) {
- case TFRC_SSTATE_NO_FBACK:
- /* RFC 3448, 4.4: Halve send rate directly */
+ /*
+ * Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4
+ */
+ if (hctx->ccid3hctx_t_rto == 0 || /* no feedback received yet */
+ hctx->ccid3hctx_p == 0) {
+
+ /* halve send rate directly */
hctx->ccid3hctx_x = max(hctx->ccid3hctx_x / 2,
(((__u64)hctx->ccid3hctx_s) << 6) /
TFRC_T_MBI);
-
- ccid3_pr_debug("%s(%p, state=%s), updated tx rate to %u "
- "bytes/s\n", dccp_role(sk), sk,
- ccid3_tx_state_name(hctx->ccid3hctx_state),
- (unsigned)(hctx->ccid3hctx_x >> 6));
- /* The value of R is still undefined and so we can not recompute
- * the timeout value. Keep initial value as per [RFC 4342, 5]. */
- t_nfb = TFRC_INITIAL_TIMEOUT;
ccid3_update_send_interval(hctx);
- break;
- case TFRC_SSTATE_FBACK:
+ } else {
/*
- * Modify the cached value of X_recv [RFC 3448, 4.4]
+ * Modify the cached value of X_recv
*
- * If (p == 0 || X_calc > 2 * X_recv)
+ * If (X_calc > 2 * X_recv)
* X_recv = max(X_recv / 2, s / (2 * t_mbi));
* Else
* X_recv = X_calc / 4;
*/
BUG_ON(hctx->ccid3hctx_p && !hctx->ccid3hctx_x_calc);
- if (hctx->ccid3hctx_p == 0 ||
- (hctx->ccid3hctx_x_calc > (hctx->ccid3hctx_x_recv >> 5))) {
-
+ if (hctx->ccid3hctx_x_calc > (hctx->ccid3hctx_x_recv >> 5))
hctx->ccid3hctx_x_recv =
max(hctx->ccid3hctx_x_recv / 2,
(((__u64)hctx->ccid3hctx_s) << 6) /
(2 * TFRC_T_MBI));
- } else {
+ else {
hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc;
hctx->ccid3hctx_x_recv <<= 4;
}
- /* Now recalculate X [RFC 3448, 4.3, step (4)] */
ccid3_hc_tx_update_x(sk, NULL);
- /*
- * Schedule no feedback timer to expire in
- * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi)
- * See comments in packet_recv() regarding the value of t_RTO.
- */
- t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi);
- break;
- case TFRC_SSTATE_NO_SENT:
- DCCP_BUG("%s(%p) - Illegal state NO_SENT", dccp_role(sk), sk);
- /* fall through */
- case TFRC_SSTATE_TERM:
- goto out;
}
+ ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n",
+ (unsigned long long)hctx->ccid3hctx_x);
+
+ /*
+ * Set new timeout for the nofeedback timer.
+ * See comments in packet_recv() regarding the value of t_RTO.
+ */
+ if (unlikely(hctx->ccid3hctx_t_rto == 0)) /* no feedback yet */
+ t_nfb = TFRC_INITIAL_TIMEOUT;
+ else
+ t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi);
restart_timer:
sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
hctx->ccid3hctx_x = rfc3390_initial_rate(sk);
hctx->ccid3hctx_t_ld = now;
} else {
- /* Sender does not have RTT sample: X = MSS/second */
- hctx->ccid3hctx_x = dp->dccps_mss_cache;
+ /*
+ * Sender does not have RTT sample:
+ * - set fallback RTT (RFC 4340, 3.4) since a RTT value
+ * is needed in several parts (e.g. window counter);
+ * - set sending rate X_pps = 1pps as per RFC 3448, 4.2.
+ */
+ hctx->ccid3hctx_rtt = DCCP_FALLBACK_RTT;
+ hctx->ccid3hctx_x = hctx->ccid3hctx_s;
hctx->ccid3hctx_x <<= 6;
}
ccid3_update_send_interval(hctx);
/* prepare to send now (add options etc.) */
dp->dccps_hc_tx_insert_options = 1;
DCCP_SKB_CB(skb)->dccpd_ccval = hctx->ccid3hctx_last_win_count;
- hctx->ccid3hctx_idle = 0;
/* set the nominal send time for the next following packet */
hctx->ccid3hctx_t_nom = ktime_add_us(hctx->ccid3hctx_t_nom,
unsigned int len)
{
struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
- struct dccp_tx_hist_entry *packet;
ccid3_hc_tx_update_s(hctx, len);
- packet = dccp_tx_hist_entry_new(ccid3_tx_hist, GFP_ATOMIC);
- if (unlikely(packet == NULL)) {
+ if (tfrc_tx_hist_add(&hctx->ccid3hctx_hist, dccp_sk(sk)->dccps_gss))
DCCP_CRIT("packet history - out of memory!");
- return;
- }
- dccp_tx_hist_add_entry(&hctx->ccid3hctx_hist, packet);
-
- packet->dccphtx_tstamp = ktime_get_real();
- packet->dccphtx_seqno = dccp_sk(sk)->dccps_gss;
- packet->dccphtx_rtt = hctx->ccid3hctx_rtt;
- packet->dccphtx_sent = 1;
}
static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
struct ccid3_options_received *opt_recv;
- struct dccp_tx_hist_entry *packet;
ktime_t now;
unsigned long t_nfb;
u32 pinv, r_sample;
if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK ||
DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK))
return;
+ /* ... and only in the established state */
+ if (hctx->ccid3hctx_state != TFRC_SSTATE_FBACK &&
+ hctx->ccid3hctx_state != TFRC_SSTATE_NO_FBACK)
+ return;
opt_recv = &hctx->ccid3hctx_options_received;
+ now = ktime_get_real();
- switch (hctx->ccid3hctx_state) {
- case TFRC_SSTATE_NO_FBACK:
- case TFRC_SSTATE_FBACK:
- /* get packet from history to look up t_recvdata */
- packet = dccp_tx_hist_find_entry(&hctx->ccid3hctx_hist,
- DCCP_SKB_CB(skb)->dccpd_ack_seq);
- if (unlikely(packet == NULL)) {
- DCCP_WARN("%s(%p), seqno %llu(%s) doesn't exist "
- "in history!\n", dccp_role(sk), sk,
- (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
- dccp_packet_name(DCCP_SKB_CB(skb)->dccpd_type));
- return;
- }
-
- /* Update receive rate in units of 64 * bytes/second */
- hctx->ccid3hctx_x_recv = opt_recv->ccid3or_receive_rate;
- hctx->ccid3hctx_x_recv <<= 6;
+ /* Estimate RTT from history if ACK number is valid */
+ r_sample = tfrc_tx_hist_rtt(hctx->ccid3hctx_hist,
+ DCCP_SKB_CB(skb)->dccpd_ack_seq, now);
+ if (r_sample == 0) {
+ DCCP_WARN("%s(%p): %s with bogus ACK-%llu\n", dccp_role(sk), sk,
+ dccp_packet_name(DCCP_SKB_CB(skb)->dccpd_type),
+ (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq);
+ return;
+ }
- /* Update loss event rate */
- pinv = opt_recv->ccid3or_loss_event_rate;
- if (pinv == ~0U || pinv == 0) /* see RFC 4342, 8.5 */
- hctx->ccid3hctx_p = 0;
- else /* can not exceed 100% */
- hctx->ccid3hctx_p = 1000000 / pinv;
+ /* Update receive rate in units of 64 * bytes/second */
+ hctx->ccid3hctx_x_recv = opt_recv->ccid3or_receive_rate;
+ hctx->ccid3hctx_x_recv <<= 6;
- now = ktime_get_real();
- /*
- * Calculate new round trip sample as per [RFC 3448, 4.3] by
- * R_sample = (now - t_recvdata) - t_elapsed
- */
- r_sample = dccp_sample_rtt(sk, ktime_us_delta(now, packet->dccphtx_tstamp));
+ /* Update loss event rate (which is scaled by 1e6) */
+ pinv = opt_recv->ccid3or_loss_event_rate;
+ if (pinv == ~0U || pinv == 0) /* see RFC 4342, 8.5 */
+ hctx->ccid3hctx_p = 0;
+ else /* can not exceed 100% */
+ hctx->ccid3hctx_p = scaled_div(1, pinv);
+ /*
+ * Validate new RTT sample and update moving average
+ */
+ r_sample = dccp_sample_rtt(sk, r_sample);
+ hctx->ccid3hctx_rtt = tfrc_ewma(hctx->ccid3hctx_rtt, r_sample, 9);
+ /*
+ * Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3
+ */
+ if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) {
+ ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
- /*
- * Update RTT estimate by
- * If (No feedback recv)
- * R = R_sample;
- * Else
- * R = q * R + (1 - q) * R_sample;
- *
- * q is a constant, RFC 3448 recomments 0.9
- */
- if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) {
+ if (hctx->ccid3hctx_t_rto == 0) {
/*
- * Larger Initial Windows [RFC 4342, sec. 5]
+ * Initial feedback packet: Larger Initial Windows (4.2)
*/
- hctx->ccid3hctx_rtt = r_sample;
hctx->ccid3hctx_x = rfc3390_initial_rate(sk);
hctx->ccid3hctx_t_ld = now;
ccid3_update_send_interval(hctx);
- ccid3_pr_debug("%s(%p), s=%u, MSS=%u, "
- "R_sample=%uus, X=%u\n", dccp_role(sk),
- sk, hctx->ccid3hctx_s,
- dccp_sk(sk)->dccps_mss_cache, r_sample,
- (unsigned)(hctx->ccid3hctx_x >> 6));
-
- ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
- } else {
- hctx->ccid3hctx_rtt = (9 * hctx->ccid3hctx_rtt +
- r_sample) / 10;
-
- /* Update sending rate (step 4 of [RFC 3448, 4.3]) */
- if (hctx->ccid3hctx_p > 0)
- hctx->ccid3hctx_x_calc =
- tfrc_calc_x(hctx->ccid3hctx_s,
- hctx->ccid3hctx_rtt,
- hctx->ccid3hctx_p);
- ccid3_hc_tx_update_x(sk, &now);
-
- ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
- "p=%u, X_calc=%u, X_recv=%u, X=%u\n",
- dccp_role(sk),
- sk, hctx->ccid3hctx_rtt, r_sample,
- hctx->ccid3hctx_s, hctx->ccid3hctx_p,
- hctx->ccid3hctx_x_calc,
- (unsigned)(hctx->ccid3hctx_x_recv >> 6),
- (unsigned)(hctx->ccid3hctx_x >> 6));
+ goto done_computing_x;
+ } else if (hctx->ccid3hctx_p == 0) {
+ /*
+ * First feedback after nofeedback timer expiry (4.3)
+ */
+ goto done_computing_x;
}
+ }
- /* unschedule no feedback timer */
- sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);
+ /* Update sending rate (step 4 of [RFC 3448, 4.3]) */
+ if (hctx->ccid3hctx_p > 0)
+ hctx->ccid3hctx_x_calc =
+ tfrc_calc_x(hctx->ccid3hctx_s,
+ hctx->ccid3hctx_rtt,
+ hctx->ccid3hctx_p);
+ ccid3_hc_tx_update_x(sk, &now);
+
+done_computing_x:
+ ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
+ "p=%u, X_calc=%u, X_recv=%u, X=%u\n",
+ dccp_role(sk),
+ sk, hctx->ccid3hctx_rtt, r_sample,
+ hctx->ccid3hctx_s, hctx->ccid3hctx_p,
+ hctx->ccid3hctx_x_calc,
+ (unsigned)(hctx->ccid3hctx_x_recv >> 6),
+ (unsigned)(hctx->ccid3hctx_x >> 6));
- /* remove all packets older than the one acked from history */
- dccp_tx_hist_purge_older(ccid3_tx_hist,
- &hctx->ccid3hctx_hist, packet);
- /*
- * As we have calculated new ipi, delta, t_nom it is possible
- * that we now can send a packet, so wake up dccp_wait_for_ccid
- */
- sk->sk_write_space(sk);
+ /* unschedule no feedback timer */
+ sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);
- /*
- * Update timeout interval for the nofeedback timer.
- * We use a configuration option to increase the lower bound.
- * This can help avoid triggering the nofeedback timer too
- * often ('spinning') on LANs with small RTTs.
- */
- hctx->ccid3hctx_t_rto = max_t(u32, 4 * hctx->ccid3hctx_rtt,
- CONFIG_IP_DCCP_CCID3_RTO *
- (USEC_PER_SEC/1000));
- /*
- * Schedule no feedback timer to expire in
- * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi)
- */
- t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi);
+ /*
+ * As we have calculated new ipi, delta, t_nom it is possible
+ * that we now can send a packet, so wake up dccp_wait_for_ccid
+ */
+ sk->sk_write_space(sk);
- ccid3_pr_debug("%s(%p), Scheduled no feedback timer to "
- "expire in %lu jiffies (%luus)\n",
- dccp_role(sk),
- sk, usecs_to_jiffies(t_nfb), t_nfb);
+ /*
+ * Update timeout interval for the nofeedback timer.
+ * We use a configuration option to increase the lower bound.
+ * This can help avoid triggering the nofeedback timer too
+ * often ('spinning') on LANs with small RTTs.
+ */
+ hctx->ccid3hctx_t_rto = max_t(u32, 4 * hctx->ccid3hctx_rtt,
+ (CONFIG_IP_DCCP_CCID3_RTO *
+ (USEC_PER_SEC / 1000)));
+ /*
+ * Schedule no feedback timer to expire in
+ * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi)
+ */
+ t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi);
- sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
- jiffies + usecs_to_jiffies(t_nfb));
+ ccid3_pr_debug("%s(%p), Scheduled no feedback timer to "
+ "expire in %lu jiffies (%luus)\n",
+ dccp_role(sk),
+ sk, usecs_to_jiffies(t_nfb), t_nfb);
- /* set idle flag */
- hctx->ccid3hctx_idle = 1;
- break;
- case TFRC_SSTATE_NO_SENT: /* fall through */
- case TFRC_SSTATE_TERM: /* ignore feedback when closing */
- break;
- }
+ sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
+ jiffies + usecs_to_jiffies(t_nfb));
}
static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option,
struct ccid3_hc_tx_sock *hctx = ccid_priv(ccid);
hctx->ccid3hctx_state = TFRC_SSTATE_NO_SENT;
- INIT_LIST_HEAD(&hctx->ccid3hctx_hist);
-
- hctx->ccid3hctx_no_feedback_timer.function =
- ccid3_hc_tx_no_feedback_timer;
- hctx->ccid3hctx_no_feedback_timer.data = (unsigned long)sk;
- init_timer(&hctx->ccid3hctx_no_feedback_timer);
+ hctx->ccid3hctx_hist = NULL;
+ setup_timer(&hctx->ccid3hctx_no_feedback_timer,
+ ccid3_hc_tx_no_feedback_timer, (unsigned long)sk);
return 0;
}
ccid3_hc_tx_set_state(sk, TFRC_SSTATE_TERM);
sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);
- /* Empty packet history */
- dccp_tx_hist_purge(ccid3_tx_hist, &hctx->ccid3hctx_hist);
+ tfrc_tx_hist_purge(&hctx->ccid3hctx_hist);
}
static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info)
/*
* 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)
{
hcrx->ccid3hcrx_state = state;
}
-static inline void ccid3_hc_rx_update_s(struct ccid3_hc_rx_sock *hcrx, int len)
-{
- if (unlikely(len == 0)) /* don't update on empty packets (e.g. ACKs) */
- ccid3_pr_debug("Packet payload length is 0 - not updating\n");
- else
- hcrx->ccid3hcrx_s = hcrx->ccid3hcrx_s == 0 ? len :
- (9 * hcrx->ccid3hcrx_s + len) / 10;
-}
-
-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 dccp_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 = 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);
- 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_last_counter = dccp_hdr(skb)->dccph_ccval;
hcrx->ccid3hcrx_bytes_recv = 0;
- /* Elapsed time information [RFC 4340, 13.2] in units of 10 * usecs */
- delta = ktime_us_delta(now, packet->dccphrx_tstamp);
- DCCP_BUG_ON(delta < 0);
- hcrx->ccid3hcrx_elapsed_time = delta / 10;
-
- 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);
}
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;
x_recv = htonl(hcrx->ccid3hcrx_x_recv);
pinv = htonl(hcrx->ccid3hcrx_pinv);
- if ((hcrx->ccid3hcrx_elapsed_time != 0 &&
- dccp_insert_option_elapsed_time(sk, skb,
- hcrx->ccid3hcrx_elapsed_time)) ||
- 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)))
return 0;
}
-static int ccid3_hc_rx_detect_loss(struct sock *sk,
- struct dccp_rx_hist_entry *packet)
+/** ccid3_first_li - Implements [RFC 3448, 6.3.1]
+ *
+ * Determine the length of the first loss interval via inverse lookup.
+ * Assume that X_recv can be computed by the throughput equation
+ * s
+ * X_recv = --------
+ * R * fval
+ * Find some p such that f(p) = fval; return 1/p (scaled).
+ */
+static u32 ccid3_first_li(struct sock *sk)
{
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;
-
+ u32 x_recv, p, delta;
+ u64 fval;
- 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;
+ if (hcrx->ccid3hcrx_rtt == 0) {
+ DCCP_WARN("No RTT estimate available, using fallback RTT\n");
+ hcrx->ccid3hcrx_rtt = DCCP_FALLBACK_RTT;
}
-
- 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);
+ delta = ktime_to_us(net_timedelta(hcrx->ccid3hcrx_tstamp_last_feedback));
+ x_recv = scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);
+ if (x_recv == 0) { /* would also trigger divide-by-zero */
+ DCCP_WARN("X_recv==0\n");
+ if ((x_recv = hcrx->ccid3hcrx_x_recv) == 0) {
+ DCCP_BUG("stored value of X_recv is zero");
+ return ~0U;
}
}
- /* 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;
- }
+ fval = scaled_div(hcrx->ccid3hcrx_s, hcrx->ccid3hcrx_rtt);
+ fval = scaled_div32(fval, x_recv);
+ p = tfrc_calc_x_reverse_lookup(fval);
+
+ ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
+ "loss rate=%u\n", dccp_role(sk), sk, x_recv, p);
-detect_out:
- dccp_rx_hist_add_packet(ccid3_rx_hist, &hcrx->ccid3hcrx_hist,
- &hcrx->ccid3hcrx_li_hist, packet,
- hcrx->ccid3hcrx_seqno_nonloss);
- return loss;
+ return p == 0 ? ~0U : scaled_div(1, p);
}
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;
+ 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);
+
+ 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
+ */
+ }
+ goto update_records;
+ }
- 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 (tfrc_rx_hist_duplicate(&hcrx->ccid3hcrx_hist, skb))
+ return; /* done receiving */
- 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;
+ 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;
}
- 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;
+ /*
+ * Handle pending losses and otherwise check for new loss
+ */
+ if (tfrc_rx_hist_loss_pending(&hcrx->ccid3hcrx_hist) &&
+ tfrc_rx_handle_loss(&hcrx->ccid3hcrx_hist,
+ &hcrx->ccid3hcrx_li_hist,
+ skb, ndp, ccid3_first_li, sk) ) {
+ do_feedback = CCID3_FBACK_PARAM_CHANGE;
+ goto done_receiving;
}
- loss = ccid3_hc_rx_detect_loss(sk, packet);
-
- if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK)
- return;
+ if (tfrc_rx_hist_new_loss_indicated(&hcrx->ccid3hcrx_hist, skb, ndp))
+ goto update_records;
- payload_size = skb->len - dccp_hdr(skb)->dccph_doff * 4;
- ccid3_hc_rx_update_s(hcrx, payload_size);
+ /*
+ * Handle data packets: RTT sampling and monitoring p
+ */
+ if (unlikely(!is_data_packet))
+ goto update_records;
- 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;
+ if (!tfrc_lh_is_initialised(&hcrx->ccid3hcrx_li_hist)) {
+ 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);
- 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;
+ } else if (tfrc_lh_update_i_mean(&hcrx->ccid3hcrx_li_hist, skb)) {
+ /*
+ * Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean
+ * has decreased (resp. p has increased), send feedback now.
+ */
+ do_feedback = CCID3_FBACK_PARAM_CHANGE;
}
- /* 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));
-
- 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);
+ /*
+ * 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;
- /* Scaling up by 1000000 as fixed decimal */
- if (i_mean != 0)
- hcrx->ccid3hcrx_p = 1000000 / i_mean;
- } else
- DCCP_BUG("empty loss history");
+update_records:
+ tfrc_rx_hist_add_packet(&hcrx->ccid3hcrx_hist, skb, ndp);
- 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)
{
struct ccid3_hc_rx_sock *hcrx = ccid_priv(ccid);
- 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;
+ tfrc_lh_init(&hcrx->ccid3hcrx_li_hist);
+ return tfrc_rx_hist_alloc(&hcrx->ccid3hcrx_hist);
}
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);
-
- /* Empty loss interval history */
- dccp_li_hist_purge(&hcrx->ccid3hcrx_li_hist);
+ tfrc_rx_hist_purge(&hcrx->ccid3hcrx_hist);
+ tfrc_lh_cleanup(&hcrx->ccid3hcrx_li_hist);
}
static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)
u32 __user *optval, int __user *optlen)
{
const struct ccid3_hc_rx_sock *hcrx;
+ struct tfrc_rx_info rx_info;
const void *val;
/* Listen socks doesn't have a private CCID block */
hcrx = ccid3_hc_rx_sk(sk);
switch (optname) {
case DCCP_SOCKOPT_CCID_RX_INFO:
- if (len < sizeof(hcrx->ccid3hcrx_tfrc))
+ if (len < sizeof(rx_info))
return -EINVAL;
- len = sizeof(hcrx->ccid3hcrx_tfrc);
- val = &hcrx->ccid3hcrx_tfrc;
+ rx_info.tfrcrx_x_recv = hcrx->ccid3hcrx_x_recv;
+ rx_info.tfrcrx_rtt = hcrx->ccid3hcrx_rtt;
+ rx_info.tfrcrx_p = hcrx->ccid3hcrx_pinv == 0 ? ~0U :
+ scaled_div(1, hcrx->ccid3hcrx_pinv);
+ len = sizeof(rx_info);
+ val = &rx_info;
break;
default:
return -ENOPROTOOPT;
static struct ccid_operations ccid3 = {
.ccid_id = DCCPC_CCID3,
- .ccid_name = "ccid3",
+ .ccid_name = "TCP-Friendly Rate Control",
.ccid_owner = THIS_MODULE,
.ccid_hc_tx_obj_size = sizeof(struct ccid3_hc_tx_sock),
.ccid_hc_tx_init = ccid3_hc_tx_init,
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;
-
- ccid3_tx_hist = dccp_tx_hist_new("ccid3");
- if (ccid3_tx_hist == NULL)
- goto out_free_rx;
-
- rc = ccid_register(&ccid3);
- if (rc != 0)
- goto out_free_tx;
-out:
- return rc;
-
-out_free_tx:
- dccp_tx_hist_delete(ccid3_tx_hist);
- ccid3_tx_hist = NULL;
-out_free_rx:
- dccp_rx_hist_delete(ccid3_rx_hist);
- ccid3_rx_hist = NULL;
- goto out;
+ return ccid_register(&ccid3);
}
module_init(ccid3_module_init);
static __exit void ccid3_module_exit(void)
{
ccid_unregister(&ccid3);
-
- if (ccid3_tx_hist != NULL) {
- dccp_tx_hist_delete(ccid3_tx_hist);
- ccid3_tx_hist = NULL;
- }
- if (ccid3_rx_hist != NULL) {
- dccp_rx_hist_delete(ccid3_rx_hist);
- ccid3_rx_hist = NULL;
- }
}
module_exit(ccid3_module_exit);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff