1 files changed, 245 insertions, 304 deletions

diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index cec23ad286de..70ebe705eb75 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -60,13 +60,11 @@ static u32 usecs_div(const u32 a, const u32 b)
         return (b >= 2 * div) ? tmp / (b / div) : tmp;
 }
 
-static int ccid3_debug;
 
-#ifdef CCID3_DEBUG
-#define ccid3_pr_debug(format, a...) \
-        do { if (ccid3_debug) \
-                printk(KERN_DEBUG "%s: " format, __FUNCTION__, ##a); \
-        } while (0)
+
+#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
+static int ccid3_debug;
+#define ccid3_pr_debug(format, a...)    DCCP_PR_DEBUG(ccid3_debug, format, ##a)
 #else
 #define ccid3_pr_debug(format, a...)
 #endif
@@ -75,15 +73,7 @@ static struct dccp_tx_hist *ccid3_tx_hist;
 static struct dccp_rx_hist *ccid3_rx_hist;
 static struct dccp_li_hist *ccid3_li_hist;
 
-/* TFRC sender states */
-enum ccid3_hc_tx_states {
-        TFRC_SSTATE_NO_SENT = 1,
-        TFRC_SSTATE_NO_FBACK,
-        TFRC_SSTATE_FBACK,
-        TFRC_SSTATE_TERM,
-};
-
-#ifdef CCID3_DEBUG
+#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
 static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state)
 {
         static char *ccid3_state_names[] = {
@@ -110,25 +100,24 @@ static void ccid3_hc_tx_set_state(struct sock *sk,
         hctx->ccid3hctx_state = state;
 }
 
-/* Calculate new t_ipi (inter packet interval) by t_ipi = s / X_inst */
-static inline void ccid3_calc_new_t_ipi(struct ccid3_hc_tx_sock *hctx)
+/*
+ * Recalculate scheduled nominal send time t_nom, inter-packet interval
+ * t_ipi, and delta value. Should be called after each change to X.
+ */
+static inline void ccid3_update_send_time(struct ccid3_hc_tx_sock *hctx)
 {
-        /*
-         * If no feedback spec says t_ipi is 1 second (set elsewhere and then
-         * doubles after every no feedback timer (separate function)
-         */
-        if (hctx->ccid3hctx_state != TFRC_SSTATE_NO_FBACK)
-                hctx->ccid3hctx_t_ipi = usecs_div(hctx->ccid3hctx_s,
-                                                  hctx->ccid3hctx_x);
-}
+        timeval_sub_usecs(&hctx->ccid3hctx_t_nom, hctx->ccid3hctx_t_ipi);
 
-/* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */
-static inline void ccid3_calc_new_delta(struct ccid3_hc_tx_sock *hctx)
-{
+        /* Calculate new t_ipi (inter packet interval) by t_ipi = s / X_inst */
+        hctx->ccid3hctx_t_ipi = usecs_div(hctx->ccid3hctx_s, hctx->ccid3hctx_x);
+
+        /* Update nominal send time with regard to the new t_ipi */
+        timeval_add_usecs(&hctx->ccid3hctx_t_nom, hctx->ccid3hctx_t_ipi);
+
+        /* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */
         hctx->ccid3hctx_delta = min_t(u32, hctx->ccid3hctx_t_ipi / 2,
                                            TFRC_OPSYS_HALF_TIME_GRAN);
 }
-
 /*
  * Update X by
  *    If (p > 0)
@@ -139,76 +128,85 @@ static inline void ccid3_calc_new_delta(struct ccid3_hc_tx_sock *hctx)
  *          X = max(min(2 * X, 2 * X_recv), s / R);
  *          tld = now;
  */ 
-static void ccid3_hc_tx_update_x(struct sock *sk)
+static void ccid3_hc_tx_update_x(struct sock *sk, struct timeval *now)
+
 {
         struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
+        const __u32 old_x = hctx->ccid3hctx_x;
 
         /* To avoid large error in calcX */
         if (hctx->ccid3hctx_p >= TFRC_SMALLEST_P) {
                 hctx->ccid3hctx_x_calc = tfrc_calc_x(hctx->ccid3hctx_s,
                                                      hctx->ccid3hctx_rtt,
                                                      hctx->ccid3hctx_p);
-                hctx->ccid3hctx_x = max_t(u32, min_t(u32, hctx->ccid3hctx_x_calc,
-                                                          2 * hctx->ccid3hctx_x_recv),
-                                               (hctx->ccid3hctx_s /
-                                                TFRC_MAX_BACK_OFF_TIME));
-        } else {
-                struct timeval now;
+                hctx->ccid3hctx_x = max_t(u32, min(hctx->ccid3hctx_x_calc,
+                                                   hctx->ccid3hctx_x_recv * 2),
+                                               hctx->ccid3hctx_s / TFRC_T_MBI);
+
+        } else if (timeval_delta(now, &hctx->ccid3hctx_t_ld) >=
+                                                          hctx->ccid3hctx_rtt) {
+                hctx->ccid3hctx_x = max(min(hctx->ccid3hctx_x_recv,
+                                            hctx->ccid3hctx_x      ) * 2,
+                                        usecs_div(hctx->ccid3hctx_s,
+                                                  hctx->ccid3hctx_rtt)   );
+                hctx->ccid3hctx_t_ld = *now;
+        } else
+                ccid3_pr_debug("Not changing X\n");
 
-                dccp_timestamp(sk, &now);
-                if (timeval_delta(&now, &hctx->ccid3hctx_t_ld) >=
-                    hctx->ccid3hctx_rtt) {
-                        hctx->ccid3hctx_x = max_t(u32, min_t(u32, hctx->ccid3hctx_x_recv,
-                                                                  hctx->ccid3hctx_x) * 2,
-                                                       usecs_div(hctx->ccid3hctx_s,
-                                                                 hctx->ccid3hctx_rtt));
-                        hctx->ccid3hctx_t_ld = now;
-                }
-        }
+        if (hctx->ccid3hctx_x != old_x)
+                ccid3_update_send_time(hctx);
+}
+
+/*
+ *      Track the mean packet size `s' (cf. RFC 4342, 5.3 and  RFC 3448, 4.1)
+ *      @len: DCCP packet payload size in bytes
+ */
+static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hctx, int len)
+{
+        if (unlikely(len == 0))
+                ccid3_pr_debug("Packet payload length is 0 - not updating\n");
+        else
+                hctx->ccid3hctx_s = hctx->ccid3hctx_s == 0 ? len :
+                                    (9 * hctx->ccid3hctx_s + len) / 10;
+        /*
+         * Note: We could do a potential optimisation here - when `s' changes,
+         *       recalculate sending rate and consequently t_ipi, t_delta, and
+         *       t_now. This is however non-standard, and the benefits are not
+         *       clear, so it is currently left out.
+         */
 }
 
 static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
 {
         struct sock *sk = (struct sock *)data;
-        unsigned long next_tmout = 0;
         struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
+        unsigned long t_nfb = USEC_PER_SEC / 5;
 
         bh_lock_sock(sk);
         if (sock_owned_by_user(sk)) {
                 /* Try again later. */
                 /* XXX: set some sensible MIB */
-                sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
-                               jiffies + HZ / 5);
-                goto out;
+                goto restart_timer;
         }
 
         ccid3_pr_debug("%s, sk=%p, state=%s\n", dccp_role(sk), sk,
                        ccid3_tx_state_name(hctx->ccid3hctx_state));
         
         switch (hctx->ccid3hctx_state) {
-        case TFRC_SSTATE_TERM:
-                goto out;
         case TFRC_SSTATE_NO_FBACK:
-                /* Halve send rate */
-                hctx->ccid3hctx_x /= 2;
-                if (hctx->ccid3hctx_x < (hctx->ccid3hctx_s /
-                                         TFRC_MAX_BACK_OFF_TIME))
-                        hctx->ccid3hctx_x = (hctx->ccid3hctx_s /
-                                             TFRC_MAX_BACK_OFF_TIME);
+                /* RFC 3448, 4.4: Halve send rate directly */
+                hctx->ccid3hctx_x = min_t(u32, hctx->ccid3hctx_x / 2,
+                                               hctx->ccid3hctx_s / TFRC_T_MBI);
 
                 ccid3_pr_debug("%s, sk=%p, state=%s, updated tx rate to %d "
                                "bytes/s\n",
                                dccp_role(sk), sk,
                                ccid3_tx_state_name(hctx->ccid3hctx_state),
                                hctx->ccid3hctx_x);
-                next_tmout = max_t(u32, 2 * usecs_div(hctx->ccid3hctx_s,
-                                                      hctx->ccid3hctx_x),
-                                        TFRC_INITIAL_TIMEOUT);
-                /*
-                 * FIXME - not sure above calculation is correct. See section
-                 * 5 of CCID3 11 should adjust tx_t_ipi and double that to
-                 * achieve it really
-                 */
+                /* The value of R is still undefined and so we can not recompute
+                 * the timout value. Keep initial value as per [RFC 4342, 5]. */
+                t_nfb = TFRC_INITIAL_TIMEOUT;
+                ccid3_update_send_time(hctx);
                 break;
         case TFRC_SSTATE_FBACK:
                 /*
@@ -218,6 +216,8 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
                 if (!hctx->ccid3hctx_idle ||
                     (hctx->ccid3hctx_x_recv >=
                      4 * usecs_div(hctx->ccid3hctx_s, hctx->ccid3hctx_rtt))) {
+                        struct timeval now;
+
                         ccid3_pr_debug("%s, sk=%p, state=%s, not idle\n",
                                        dccp_role(sk), sk,
                                        ccid3_tx_state_name(hctx->ccid3hctx_state));
@@ -235,55 +235,60 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
                         if (hctx->ccid3hctx_p < TFRC_SMALLEST_P ||
                             hctx->ccid3hctx_x_calc > 2 * hctx->ccid3hctx_x_recv)
                                 hctx->ccid3hctx_x_recv = max_t(u32, hctx->ccid3hctx_x_recv / 2,
-                                                                    hctx->ccid3hctx_s / (2 * TFRC_MAX_BACK_OFF_TIME));
+                                                                    hctx->ccid3hctx_s / (2 * TFRC_T_MBI));
                         else
                                 hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc / 4;
 
                         /* Update sending rate */
-                        ccid3_hc_tx_update_x(sk);
+                        dccp_timestamp(sk, &now);
+                        ccid3_hc_tx_update_x(sk, &now);
                 }
                 /*
                  * Schedule no feedback timer to expire in
-                 * max(4 * R, 2 * s / X)
+                 * max(4 * R, 2 * s/X)  =  max(4 * R, 2 * t_ipi)
                  */
-                next_tmout = max_t(u32, hctx->ccid3hctx_t_rto, 
-                                        2 * usecs_div(hctx->ccid3hctx_s,
-                                                      hctx->ccid3hctx_x));
+                t_nfb = max(4 * hctx->ccid3hctx_rtt, 2 * hctx->ccid3hctx_t_ipi);
                 break;
-        default:
-                printk(KERN_CRIT "%s: %s, sk=%p, Illegal state (%d)!\n",
-                       __FUNCTION__, dccp_role(sk), sk, hctx->ccid3hctx_state);
-                dump_stack();
+        case TFRC_SSTATE_NO_SENT:
+                DCCP_BUG("Illegal %s state NO_SENT, sk=%p", dccp_role(sk), sk);
+                /* fall through */
+        case TFRC_SSTATE_TERM:
                 goto out;
         }
 
-        sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer, 
-                      jiffies + max_t(u32, 1, usecs_to_jiffies(next_tmout)));
         hctx->ccid3hctx_idle = 1;
+
+restart_timer:
+        sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
+                           jiffies + usecs_to_jiffies(t_nfb));
 out:
         bh_unlock_sock(sk);
         sock_put(sk);
 }
 
-static int ccid3_hc_tx_send_packet(struct sock *sk,
-                                   struct sk_buff *skb, int len)
+/*
+ * returns
+ *   > 0: delay (in msecs) that should pass before actually sending
+ *   = 0: can send immediately
+ *   < 0: error condition; do not send packet
+ */
+static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
 {
         struct dccp_sock *dp = dccp_sk(sk);
         struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
         struct dccp_tx_hist_entry *new_packet;
         struct timeval now;
         long delay;
-        int rc = -ENOTCONN;
 
-        BUG_ON(hctx == NULL || hctx->ccid3hctx_state == TFRC_SSTATE_TERM);
+        BUG_ON(hctx == NULL);
 
-        /* Check if pure ACK or Terminating*/
         /*
-         * XXX: We only call this function for DATA and DATAACK, on, these
-         * packets can have zero length, but why the comment about "pure ACK"?
+         * This function is called only for Data and DataAck packets. Sending
+         * zero-sized Data(Ack)s is theoretically possible, but for congestion
+         * control this case is pathological - ignore it.
          */
-        if (unlikely(len == 0))
-                goto out;
+        if (unlikely(skb->len == 0))
+                return -EBADMSG;
 
         /* See if last packet allocated was not sent */
         new_packet = dccp_tx_hist_head(&hctx->ccid3hctx_hist);
@@ -291,12 +296,10 @@ static int ccid3_hc_tx_send_packet(struct sock *sk,
                 new_packet = dccp_tx_hist_entry_new(ccid3_tx_hist,
                                                     SLAB_ATOMIC);
 
-                rc = -ENOBUFS;
                 if (unlikely(new_packet == NULL)) {
-                        LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, not enough "
-                                       "mem to add to history, send refused\n",
-                                       __FUNCTION__, dccp_role(sk), sk);
-                        goto out;
+                        DCCP_WARN("%s, sk=%p, not enough mem to add to history,"
+                                  "send refused\n", dccp_role(sk), sk);
+                        return -ENOBUFS;
                 }
 
                 dccp_tx_hist_add_entry(&hctx->ccid3hctx_hist, new_packet);
@@ -311,123 +314,94 @@ static int ccid3_hc_tx_send_packet(struct sock *sk,
                 hctx->ccid3hctx_last_win_count   = 0;
                 hctx->ccid3hctx_t_last_win_count = now;
                 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
-                hctx->ccid3hctx_t_ipi = TFRC_INITIAL_IPI;
 
-                /* Set nominal send time for initial packet */
+                /* Set initial sending rate to 1 packet per second */
+                ccid3_hc_tx_update_s(hctx, skb->len);
+                hctx->ccid3hctx_x     = hctx->ccid3hctx_s;
+
+                /* First timeout, according to [RFC 3448, 4.2], is 1 second */
+                hctx->ccid3hctx_t_ipi = USEC_PER_SEC;
+                /* Initial delta: minimum of 0.5 sec and t_gran/2 */
+                hctx->ccid3hctx_delta = TFRC_OPSYS_HALF_TIME_GRAN;
+
+                /* Set t_0 for initial packet */
                 hctx->ccid3hctx_t_nom = now;
-                timeval_add_usecs(&hctx->ccid3hctx_t_nom,
-                                  hctx->ccid3hctx_t_ipi);
-                ccid3_calc_new_delta(hctx);
-                rc = 0;
                 break;
         case TFRC_SSTATE_NO_FBACK:
         case TFRC_SSTATE_FBACK:
-                delay = (timeval_delta(&now, &hctx->ccid3hctx_t_nom) -
-                         hctx->ccid3hctx_delta);
-                delay /= -1000;
-                /* divide by -1000 is to convert to ms and get sign right */
-                rc = delay > 0 ? delay : 0;
-                break;
-        default:
-                printk(KERN_CRIT "%s: %s, sk=%p, Illegal state (%d)!\n",
-                       __FUNCTION__, dccp_role(sk), sk, hctx->ccid3hctx_state);
-                dump_stack();
-                rc = -EINVAL;
+                delay = timeval_delta(&hctx->ccid3hctx_t_nom, &now);
+                /*
+                 *      Scheduling of packet transmissions [RFC 3448, 4.6]
+                 *
+                 * if (t_now > t_nom - delta)
+                 *       // send the packet now
+                 * else
+                 *       // send the packet in (t_nom - t_now) milliseconds.
+                 */
+                if (delay >= hctx->ccid3hctx_delta)
+                        return delay / 1000L;
                 break;
+        case TFRC_SSTATE_TERM:
+                DCCP_BUG("Illegal %s state TERM, sk=%p", dccp_role(sk), sk);
+                return -EINVAL;
         }
 
-        /* Can we send? if so add options and add to packet history */
-        if (rc == 0) {
-                dp->dccps_hc_tx_insert_options = 1;
-                new_packet->dccphtx_ccval =
-                        DCCP_SKB_CB(skb)->dccpd_ccval =
-                                hctx->ccid3hctx_last_win_count;
-                timeval_add_usecs(&hctx->ccid3hctx_t_nom,
-                                  hctx->ccid3hctx_t_ipi);
-        }
-out:
-        return rc;
+        /* prepare to send now (add options etc.) */
+        dp->dccps_hc_tx_insert_options = 1;
+        new_packet->dccphtx_ccval = DCCP_SKB_CB(skb)->dccpd_ccval =
+                                    hctx->ccid3hctx_last_win_count;
+        timeval_add_usecs(&hctx->ccid3hctx_t_nom, hctx->ccid3hctx_t_ipi);
+
+        return 0;
 }
 
-static void ccid3_hc_tx_packet_sent(struct sock *sk, int more, int len)
+static void ccid3_hc_tx_packet_sent(struct sock *sk, int more, unsigned int len)
 {
         const struct dccp_sock *dp = dccp_sk(sk);
         struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
         struct timeval now;
+        unsigned long quarter_rtt;
+        struct dccp_tx_hist_entry *packet;
 
-        BUG_ON(hctx == NULL || hctx->ccid3hctx_state == TFRC_SSTATE_TERM);
+        BUG_ON(hctx == NULL);
 
         dccp_timestamp(sk, &now);
 
-        /* check if we have sent a data packet */
-        if (len > 0) {
-                unsigned long quarter_rtt;
-                struct dccp_tx_hist_entry *packet;
+        ccid3_hc_tx_update_s(hctx, len);
 
-                packet = dccp_tx_hist_head(&hctx->ccid3hctx_hist);
-                if (unlikely(packet == NULL)) {
-                        LIMIT_NETDEBUG(KERN_WARNING "%s: packet doesn't "
-                                       "exists in history!\n", __FUNCTION__);
-                        return;
-                }
-                if (unlikely(packet->dccphtx_sent)) {
-                        LIMIT_NETDEBUG(KERN_WARNING "%s: no unsent packet in "
-                                       "history!\n", __FUNCTION__);
-                        return;
-                }
-                packet->dccphtx_tstamp = now;
-                packet->dccphtx_seqno  = dp->dccps_gss;
-                /*
-                 * Check if win_count have changed
-                 * Algorithm in "8.1. Window Counter Value" in RFC 4342.
-                 */
-                quarter_rtt = timeval_delta(&now, &hctx->ccid3hctx_t_last_win_count);
-                if (likely(hctx->ccid3hctx_rtt > 8))
-                        quarter_rtt /= hctx->ccid3hctx_rtt / 4;
-
-                if (quarter_rtt > 0) {
-                        hctx->ccid3hctx_t_last_win_count = now;
-                        hctx->ccid3hctx_last_win_count   = (hctx->ccid3hctx_last_win_count +
-                                                            min_t(unsigned long, quarter_rtt, 5)) % 16;
-                        ccid3_pr_debug("%s, sk=%p, window changed from "
-                                       "%u to %u!\n",
-                                       dccp_role(sk), sk,
-                                       packet->dccphtx_ccval,
-                                       hctx->ccid3hctx_last_win_count);
-                }
-
-                hctx->ccid3hctx_idle = 0;
-                packet->dccphtx_rtt  = hctx->ccid3hctx_rtt;
-                packet->dccphtx_sent = 1;
-        } else
-                ccid3_pr_debug("%s, sk=%p, seqno=%llu NOT inserted!\n",
-                               dccp_role(sk), sk, dp->dccps_gss);
-
-        switch (hctx->ccid3hctx_state) {
-        case TFRC_SSTATE_NO_SENT:
-                /* if first wasn't pure ack */
-                if (len != 0)
-                        printk(KERN_CRIT "%s: %s, First packet sent is noted "
-                                         "as a data packet\n",
-                               __FUNCTION__, dccp_role(sk));
+        packet = dccp_tx_hist_head(&hctx->ccid3hctx_hist);
+        if (unlikely(packet == NULL)) {
+                DCCP_WARN("packet doesn't exist in history!\n");
                 return;
-        case TFRC_SSTATE_NO_FBACK:
-        case TFRC_SSTATE_FBACK:
-                if (len > 0) {
-                        timeval_sub_usecs(&hctx->ccid3hctx_t_nom,
-                                  hctx->ccid3hctx_t_ipi);
-                        ccid3_calc_new_t_ipi(hctx);
-                        ccid3_calc_new_delta(hctx);
-                        timeval_add_usecs(&hctx->ccid3hctx_t_nom,
-                                          hctx->ccid3hctx_t_ipi);
-                }
-                break;
-        default:
-                printk(KERN_CRIT "%s: %s, sk=%p, Illegal state (%d)!\n",
-                       __FUNCTION__, dccp_role(sk), sk, hctx->ccid3hctx_state);
-                dump_stack();
-                break;
         }
+        if (unlikely(packet->dccphtx_sent)) {
+                DCCP_WARN("no unsent packet in history!\n");
+                return;
+        }
+        packet->dccphtx_tstamp = now;
+        packet->dccphtx_seqno  = dp->dccps_gss;
+        /*
+         * Check if win_count have changed
+         * Algorithm in "8.1. Window Counter Value" in RFC 4342.
+         */
+        quarter_rtt = timeval_delta(&now, &hctx->ccid3hctx_t_last_win_count);
+        if (likely(hctx->ccid3hctx_rtt > 8))
+                quarter_rtt /= hctx->ccid3hctx_rtt / 4;
+
+        if (quarter_rtt > 0) {
+                hctx->ccid3hctx_t_last_win_count = now;
+                hctx->ccid3hctx_last_win_count   = (hctx->ccid3hctx_last_win_count +
+                                                    min_t(unsigned long, quarter_rtt, 5)) % 16;
+                ccid3_pr_debug("%s, sk=%p, window changed from "
+                               "%u to %u!\n",
+                               dccp_role(sk), sk,
+                               packet->dccphtx_ccval,
+                               hctx->ccid3hctx_last_win_count);
+        }
+
+        hctx->ccid3hctx_idle = 0;
+        packet->dccphtx_rtt  = hctx->ccid3hctx_rtt;
+        packet->dccphtx_sent = 1;
 }
 
 static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
@@ -437,13 +411,13 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
         struct ccid3_options_received *opt_recv;
         struct dccp_tx_hist_entry *packet;
         struct timeval now;
-        unsigned long next_tmout; 
+        unsigned long t_nfb;
         u32 t_elapsed;
         u32 pinv;
         u32 x_recv;
         u32 r_sample;
 
-        BUG_ON(hctx == NULL || hctx->ccid3hctx_state == TFRC_SSTATE_TERM);
+        BUG_ON(hctx == NULL);
 
         /* we are only interested in ACKs */
         if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK ||
@@ -457,9 +431,6 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
         pinv = opt_recv->ccid3or_loss_event_rate;
 
         switch (hctx->ccid3hctx_state) {
-        case TFRC_SSTATE_NO_SENT:
-                /* FIXME: what to do here? */
-                return;
         case TFRC_SSTATE_NO_FBACK:
         case TFRC_SSTATE_FBACK:
                 /* Calculate new round trip sample by
@@ -468,11 +439,10 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
                 packet = dccp_tx_hist_find_entry(&hctx->ccid3hctx_hist,
                                                  DCCP_SKB_CB(skb)->dccpd_ack_seq);
                 if (unlikely(packet == NULL)) {
-                        LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, seqno "
-                                       "%llu(%s) does't exist in history!\n",
-                                       __FUNCTION__, dccp_role(sk), sk,
+                        DCCP_WARN("%s, sk=%p, seqno %llu(%s) does'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));
+                                  dccp_packet_name(DCCP_SKB_CB(skb)->dccpd_type));
                         return;
                 }
 
@@ -480,9 +450,8 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
                 dccp_timestamp(sk, &now);
                 r_sample = timeval_delta(&now, &packet->dccphtx_tstamp);
                 if (unlikely(r_sample <= t_elapsed))
-                        LIMIT_NETDEBUG(KERN_WARNING "%s: r_sample=%uus, "
-                                       "t_elapsed=%uus\n",
-                                       __FUNCTION__, r_sample, t_elapsed);
+                        DCCP_WARN("r_sample=%uus,t_elapsed=%uus\n",
+                                  r_sample, t_elapsed);
                 else
                         r_sample -= t_elapsed;
 
@@ -495,20 +464,26 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
                  * q is a constant, RFC 3448 recomments 0.9
                  */
                 if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) {
+                        /* Use Larger Initial Windows [RFC 4342, sec. 5]
+                         * We deviate in that we use `s' instead of `MSS'. */
+                        u16 w_init = max(    4 * hctx->ccid3hctx_s,
+                                         max(2 * hctx->ccid3hctx_s, 4380));
+                        hctx->ccid3hctx_rtt  = r_sample;
+                        hctx->ccid3hctx_x    = usecs_div(w_init, r_sample);
+                        hctx->ccid3hctx_t_ld = now;
+
+                        ccid3_update_send_time(hctx);
                         ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
-                        hctx->ccid3hctx_rtt = r_sample;
-                } else
+                } else {
                         hctx->ccid3hctx_rtt = (hctx->ccid3hctx_rtt * 9) / 10 +
                                               r_sample / 10;
+                        ccid3_hc_tx_update_x(sk, &now);
+                }
 
                 ccid3_pr_debug("%s, sk=%p, New RTT estimate=%uus, "
                                "r_sample=%us\n", dccp_role(sk), sk,
                                hctx->ccid3hctx_rtt, r_sample);
 
-                /* Update timeout interval */
-                hctx->ccid3hctx_t_rto = max_t(u32, 4 * hctx->ccid3hctx_rtt,
-                                              USEC_PER_SEC);
-
                 /* Update receive rate */
                 hctx->ccid3hctx_x_recv = x_recv;/* X_recv in bytes per sec */
 
@@ -528,49 +503,41 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
                 /* unschedule no feedback timer */
                 sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);
 
-                /* Update sending rate */
-                ccid3_hc_tx_update_x(sk);
-
-                /* Update next send time */
-                timeval_sub_usecs(&hctx->ccid3hctx_t_nom,
-                                  hctx->ccid3hctx_t_ipi);
-                ccid3_calc_new_t_ipi(hctx);
-                timeval_add_usecs(&hctx->ccid3hctx_t_nom,
-                                  hctx->ccid3hctx_t_ipi);
-                ccid3_calc_new_delta(hctx);
-
                 /* 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_ccids.
+                 * we now can send a packet, so wake up dccp_wait_for_ccid
                  */
                 sk->sk_write_space(sk);
 
+                /* Update timeout interval. We use the alternative variant of
+                 * [RFC 3448, 3.1] which sets the upper bound of t_rto to one
+                 * second, as it is suggested for TCP (see RFC 2988, 2.4). */
+                hctx->ccid3hctx_t_rto = max_t(u32, 4 * hctx->ccid3hctx_rtt,
+                                                   USEC_PER_SEC            );
                 /*
                  * Schedule no feedback timer to expire in
-                 * max(4 * R, 2 * s / X)
+                 * max(4 * R, 2 * s/X)  =  max(4 * R, 2 * t_ipi)
                  */
-                next_tmout = max(hctx->ccid3hctx_t_rto,
-                                 2 * usecs_div(hctx->ccid3hctx_s,
-                                               hctx->ccid3hctx_x));
+                t_nfb = max(4 * hctx->ccid3hctx_rtt, 2 * hctx->ccid3hctx_t_ipi);
                         
                 ccid3_pr_debug("%s, sk=%p, Scheduled no feedback timer to "
                                "expire in %lu jiffies (%luus)\n",
                                dccp_role(sk), sk,
-                               usecs_to_jiffies(next_tmout), next_tmout); 
+                               usecs_to_jiffies(t_nfb), t_nfb);
 
                 sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer, 
-                               jiffies + max_t(u32, 1, usecs_to_jiffies(next_tmout)));
+                                   jiffies + usecs_to_jiffies(t_nfb));
 
                 /* set idle flag */
                 hctx->ccid3hctx_idle = 1;   
                 break;
-        default:
-                printk(KERN_CRIT "%s: %s, sk=%p, Illegal state (%d)!\n",
-                       __FUNCTION__, dccp_role(sk), sk, hctx->ccid3hctx_state);
-                dump_stack();
+        case TFRC_SSTATE_NO_SENT:
+                DCCP_WARN("Illegal ACK received - no packet has been sent\n");
+                /* fall through */
+        case TFRC_SSTATE_TERM:          /* ignore feedback when closing */
                 break;
         }
 }
@@ -610,9 +577,9 @@ static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option,
         switch (option) {
         case TFRC_OPT_LOSS_EVENT_RATE:
                 if (unlikely(len != 4)) {
-                        LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, invalid "
-                                       "len for TFRC_OPT_LOSS_EVENT_RATE\n",
-                                       __FUNCTION__, dccp_role(sk), sk);
+                        DCCP_WARN("%s, sk=%p, invalid len %d "
+                                  "for TFRC_OPT_LOSS_EVENT_RATE\n",
+                                  dccp_role(sk), sk, len);
                         rc = -EINVAL;
                 } else {
                         opt_recv->ccid3or_loss_event_rate = ntohl(*(__be32 *)value);
@@ -631,9 +598,9 @@ static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option,
                 break;
         case TFRC_OPT_RECEIVE_RATE:
                 if (unlikely(len != 4)) {
-                        LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, invalid "
-                                       "len for TFRC_OPT_RECEIVE_RATE\n",
-                                       __FUNCTION__, dccp_role(sk), sk);
+                        DCCP_WARN("%s, sk=%p, invalid len %d "
+                                  "for TFRC_OPT_RECEIVE_RATE\n",
+                                  dccp_role(sk), sk, len);
                         rc = -EINVAL;
                 } else {
                         opt_recv->ccid3or_receive_rate = ntohl(*(__be32 *)value);
@@ -649,18 +616,9 @@ static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option,
 
 static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk)
 {
-        struct dccp_sock *dp = dccp_sk(sk);
         struct ccid3_hc_tx_sock *hctx = ccid_priv(ccid);
 
-        if (dp->dccps_packet_size >= TFRC_MIN_PACKET_SIZE &&
-            dp->dccps_packet_size <= TFRC_MAX_PACKET_SIZE)
-                hctx->ccid3hctx_s = dp->dccps_packet_size;
-        else
-                hctx->ccid3hctx_s = TFRC_STD_PACKET_SIZE;
-
-        /* Set transmission rate to 1 packet per second */
-        hctx->ccid3hctx_x     = hctx->ccid3hctx_s;
-        hctx->ccid3hctx_t_rto = USEC_PER_SEC;
+        hctx->ccid3hctx_s     = 0;
         hctx->ccid3hctx_state = TFRC_SSTATE_NO_SENT;
         INIT_LIST_HEAD(&hctx->ccid3hctx_hist);
 
@@ -688,14 +646,7 @@ static void ccid3_hc_tx_exit(struct sock *sk)
  * RX Half Connection methods
  */
 
-/* TFRC receiver states */
-enum ccid3_hc_rx_states {
-        TFRC_RSTATE_NO_DATA = 1,
-        TFRC_RSTATE_DATA,
-        TFRC_RSTATE_TERM    = 127,
-};
-
-#ifdef CCID3_DEBUG
+#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
 static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state)
 {
         static char *ccid3_rx_state_names[] = {
@@ -721,6 +672,15 @@ 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 (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)
 {
         struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
@@ -743,18 +703,15 @@ static void ccid3_hc_rx_send_feedback(struct sock *sk)
                                                    delta);
         }
                 break;
-        default:
-                printk(KERN_CRIT "%s: %s, sk=%p, Illegal state (%d)!\n",
-                       __FUNCTION__, dccp_role(sk), sk, hcrx->ccid3hcrx_state);
-                dump_stack();
+        case TFRC_RSTATE_TERM:
+                DCCP_BUG("Illegal %s state TERM, sk=%p", dccp_role(sk), sk);
                 return;
         }
 
         packet = dccp_rx_hist_find_data_packet(&hcrx->ccid3hcrx_hist);
         if (unlikely(packet == NULL)) {
-                LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, no data packet "
-                               "in history!\n",
-                               __FUNCTION__, dccp_role(sk), sk);
+                DCCP_WARN("%s, sk=%p, no data packet in history!\n",
+                          dccp_role(sk), sk);
                 return;
         }
 
@@ -842,29 +799,29 @@ static u32 ccid3_hc_rx_calc_first_li(struct sock *sk)
         }
 
         if (unlikely(step == 0)) {
-                LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, packet history "
-                               "contains no data packets!\n",
-                               __FUNCTION__, dccp_role(sk), sk);
+                DCCP_WARN("%s, sk=%p, packet history has no data packets!\n",
+                          dccp_role(sk), sk);
                 return ~0;
         }
 
         if (unlikely(interval == 0)) {
-                LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, Could not find a "
-                               "win_count interval > 0. Defaulting to 1\n",
-                               __FUNCTION__, dccp_role(sk), sk);
+                DCCP_WARN("%s, sk=%p, Could not find a win_count interval > 0."
+                          "Defaulting to 1\n", dccp_role(sk), sk);
                 interval = 1;
         }
 found:
         if (!tail) {
-                LIMIT_NETDEBUG(KERN_WARNING "%s: tail is null\n",
-                   __FUNCTION__);
+                DCCP_CRIT("tail is null\n");
                 return ~0;
         }
         rtt = timeval_delta(&tstamp, &tail->dccphrx_tstamp) * 4 / interval;
         ccid3_pr_debug("%s, sk=%p, approximated RTT to %uus\n",
                        dccp_role(sk), sk, rtt);
-        if (rtt == 0)
-                rtt = 1;
+
+        if (rtt == 0) {
+                DCCP_WARN("RTT==0, setting to 1\n");
+                rtt = 1;
+        }
 
         dccp_timestamp(sk, &tstamp);
         delta = timeval_delta(&tstamp, &hcrx->ccid3hcrx_tstamp_last_feedback);
@@ -878,9 +835,7 @@ found:
         tmp2 = (u32)tmp1;
 
         if (!tmp2) {
-                LIMIT_NETDEBUG(KERN_WARNING "tmp2 = 0 "
-                   "%s: x_recv = %u, rtt =%u\n",
-                   __FUNCTION__, x_recv, rtt);
+                DCCP_CRIT("tmp2 = 0, x_recv = %u, rtt =%u\n", x_recv, rtt);
                 return ~0;
         }
 
@@ -926,8 +881,7 @@ static void ccid3_hc_rx_update_li(struct sock *sk, u64 seq_loss, u8 win_loss)
                 entry = dccp_li_hist_entry_new(ccid3_li_hist, SLAB_ATOMIC);
 
                 if (entry == NULL) {
-                        printk(KERN_CRIT "%s: out of memory\n",__FUNCTION__);
-                        dump_stack();
+                        DCCP_BUG("out of memory - can not allocate entry");
                         return;
                 }
 
@@ -1002,13 +956,10 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
         const struct dccp_options_received *opt_recv;
         struct dccp_rx_hist_entry *packet;
         struct timeval now;
-        u8 win_count;
         u32 p_prev, rtt_prev, r_sample, t_elapsed;
-        int loss;
+        int loss, payload_size;
 
-        BUG_ON(hcrx == NULL ||
-               !(hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA ||
-                 hcrx->ccid3hcrx_state == TFRC_RSTATE_DATA));
+        BUG_ON(hcrx == NULL);
 
         opt_recv = &dccp_sk(sk)->dccps_options_received;
 
@@ -1026,9 +977,8 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
                 t_elapsed = opt_recv->dccpor_elapsed_time * 10;
 
                 if (unlikely(r_sample <= t_elapsed))
-                        LIMIT_NETDEBUG(KERN_WARNING "%s: r_sample=%uus, "
-                                       "t_elapsed=%uus\n",
-                                       __FUNCTION__, r_sample, t_elapsed);
+                        DCCP_WARN("r_sample=%uus, t_elapsed=%uus\n",
+                                  r_sample, t_elapsed);
                 else
                         r_sample -= t_elapsed;
 
@@ -1052,19 +1002,19 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
         packet = dccp_rx_hist_entry_new(ccid3_rx_hist, sk, opt_recv->dccpor_ndp,
                                         skb, SLAB_ATOMIC);
         if (unlikely(packet == NULL)) {
-                LIMIT_NETDEBUG(KERN_WARNING "%s: %s, sk=%p, Not enough mem to "
-                                "add rx packet to history, consider it lost!\n",
-                               __FUNCTION__, dccp_role(sk), sk);
+                DCCP_WARN("%s, sk=%p, Not enough mem to add rx packet "
+                          "to history, consider it lost!\n", dccp_role(sk), sk);
                 return;
         }
 
-        win_count = packet->dccphrx_ccval;
-
         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, sk=%p(%s), skb=%p, sending initial "
@@ -1075,8 +1025,7 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
                 ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA);
                 return;
         case TFRC_RSTATE_DATA:
-                hcrx->ccid3hcrx_bytes_recv += skb->len -
-                                              dccp_hdr(skb)->dccph_doff * 4;
+                hcrx->ccid3hcrx_bytes_recv += payload_size;
                 if (loss)
                         break;
 
@@ -1087,10 +1036,8 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
                         ccid3_hc_rx_send_feedback(sk);
                 }
                 return;
-        default:
-                printk(KERN_CRIT "%s: %s, sk=%p, Illegal state (%d)!\n",
-                       __FUNCTION__, dccp_role(sk), sk, hcrx->ccid3hcrx_state);
-                dump_stack();
+        case TFRC_RSTATE_TERM:
+                DCCP_BUG("Illegal %s state TERM, sk=%p", dccp_role(sk), sk);
                 return;
         }
 
@@ -1107,10 +1054,8 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
                 /* Scaling up by 1000000 as fixed decimal */
                 if (i_mean != 0)
                         hcrx->ccid3hcrx_p = 1000000 / i_mean;
-        } else {
-                printk(KERN_CRIT "%s: empty loss hist\n",__FUNCTION__);
-                dump_stack();
-        }
+        } else
+                DCCP_BUG("empty loss history");
 
         if (hcrx->ccid3hcrx_p > p_prev) {
                 ccid3_hc_rx_send_feedback(sk);
@@ -1120,22 +1065,16 @@ static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
 
 static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
 {
-        struct dccp_sock *dp = dccp_sk(sk);
         struct ccid3_hc_rx_sock *hcrx = ccid_priv(ccid);
 
         ccid3_pr_debug("%s, sk=%p\n", dccp_role(sk), sk);
 
-        if (dp->dccps_packet_size >= TFRC_MIN_PACKET_SIZE &&
-            dp->dccps_packet_size <= TFRC_MAX_PACKET_SIZE)
-                hcrx->ccid3hcrx_s = dp->dccps_packet_size;
-        else
-                hcrx->ccid3hcrx_s = TFRC_STD_PACKET_SIZE;
-
         hcrx->ccid3hcrx_state = TFRC_RSTATE_NO_DATA;
         INIT_LIST_HEAD(&hcrx->ccid3hcrx_hist);
         INIT_LIST_HEAD(&hcrx->ccid3hcrx_li_hist);
         dccp_timestamp(sk, &hcrx->ccid3hcrx_tstamp_last_ack);
         hcrx->ccid3hcrx_tstamp_last_feedback = hcrx->ccid3hcrx_tstamp_last_ack;
+        hcrx->ccid3hcrx_s   = 0;
         hcrx->ccid3hcrx_rtt = 5000; /* XXX 5ms for now... */
         return 0;
 }
@@ -1261,8 +1200,10 @@ static struct ccid_operations ccid3 = {
         .ccid_hc_tx_getsockopt     = ccid3_hc_tx_getsockopt,
 };
  
+#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
 module_param(ccid3_debug, int, 0444);
 MODULE_PARM_DESC(ccid3_debug, "Enable debug messages");
+#endif
 
 static __init int ccid3_module_init(void)
 {