This reverts "Merge branch 'dccp' of git://eden-feed.erg.abdn.ac.uk/dccp_exp"

as it accentally contained the wrong set of patches. These will be
submitted separately.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

1 files changed, 372 insertions, 250 deletions

diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
index fa713227c66f..9a430734530c 100644
--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -25,7 +25,7 @@
 /*
  * This implementation should follow RFC 4341
  */
-#include "../feat.h"
+
 #include "../ccid.h"
 #include "../dccp.h"
 #include "ccid2.h"
@@ -34,8 +34,51 @@
 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
 static int ccid2_debug;
 #define ccid2_pr_debug(format, a...)    DCCP_PR_DEBUG(ccid2_debug, format, ##a)
+
+static void ccid2_hc_tx_check_sanity(const struct ccid2_hc_tx_sock *hctx)
+{
+        int len = 0;
+        int pipe = 0;
+        struct ccid2_seq *seqp = hctx->ccid2hctx_seqh;
+
+        /* there is data in the chain */
+        if (seqp != hctx->ccid2hctx_seqt) {
+                seqp = seqp->ccid2s_prev;
+                len++;
+                if (!seqp->ccid2s_acked)
+                        pipe++;
+
+                while (seqp != hctx->ccid2hctx_seqt) {
+                        struct ccid2_seq *prev = seqp->ccid2s_prev;
+
+                        len++;
+                        if (!prev->ccid2s_acked)
+                                pipe++;
+
+                        /* packets are sent sequentially */
+                        BUG_ON(dccp_delta_seqno(seqp->ccid2s_seq,
+                                                prev->ccid2s_seq ) >= 0);
+                        BUG_ON(time_before(seqp->ccid2s_sent,
+                                           prev->ccid2s_sent));
+
+                        seqp = prev;
+                }
+        }
+
+        BUG_ON(pipe != hctx->ccid2hctx_pipe);
+        ccid2_pr_debug("len of chain=%d\n", len);
+
+        do {
+                seqp = seqp->ccid2s_prev;
+                len++;
+        } while (seqp != hctx->ccid2hctx_seqh);
+
+        ccid2_pr_debug("total len=%d\n", len);
+        BUG_ON(len != hctx->ccid2hctx_seqbufc * CCID2_SEQBUF_LEN);
+}
 #else
 #define ccid2_pr_debug(format, a...)
+#define ccid2_hc_tx_check_sanity(hctx)
 #endif
 
 static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hctx)
@@ -44,7 +87,8 @@ static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hctx)
         int i;
 
         /* check if we have space to preserve the pointer to the buffer */
-        if (hctx->seqbufc >= sizeof(hctx->seqbuf) / sizeof(struct ccid2_seq *))
+        if (hctx->ccid2hctx_seqbufc >= (sizeof(hctx->ccid2hctx_seqbuf) /
+                                        sizeof(struct ccid2_seq*)))
                 return -ENOMEM;
 
         /* allocate buffer and initialize linked list */
@@ -60,35 +104,38 @@ static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hctx)
         seqp->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
 
         /* This is the first allocation.  Initiate the head and tail.  */
-        if (hctx->seqbufc == 0)
-                hctx->seqh = hctx->seqt = seqp;
+        if (hctx->ccid2hctx_seqbufc == 0)
+                hctx->ccid2hctx_seqh = hctx->ccid2hctx_seqt = seqp;
         else {
                 /* link the existing list with the one we just created */
-                hctx->seqh->ccid2s_next = seqp;
-                seqp->ccid2s_prev = hctx->seqh;
+                hctx->ccid2hctx_seqh->ccid2s_next = seqp;
+                seqp->ccid2s_prev = hctx->ccid2hctx_seqh;
 
-                hctx->seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
-                seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hctx->seqt;
+                hctx->ccid2hctx_seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
+                seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hctx->ccid2hctx_seqt;
         }
 
         /* store the original pointer to the buffer so we can free it */
-        hctx->seqbuf[hctx->seqbufc] = seqp;
-        hctx->seqbufc++;
+        hctx->ccid2hctx_seqbuf[hctx->ccid2hctx_seqbufc] = seqp;
+        hctx->ccid2hctx_seqbufc++;
 
         return 0;
 }
 
 static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
 {
-        if (ccid2_cwnd_network_limited(ccid2_hc_tx_sk(sk)))
-                return CCID_PACKET_WILL_DEQUEUE_LATER;
-        return CCID_PACKET_SEND_AT_ONCE;
+        struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+
+        if (hctx->ccid2hctx_pipe < hctx->ccid2hctx_cwnd)
+                return 0;
+
+        return 1; /* XXX CCID should dequeue when ready instead of polling */
 }
 
 static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
 {
         struct dccp_sock *dp = dccp_sk(sk);
-        u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->cwnd, 2);
+        u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->ccid2hctx_cwnd, 2);
 
         /*
          * Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from
@@ -100,8 +147,8 @@ static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
                 DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio);
                 val = max_ratio;
         }
-        if (val > DCCPF_ACK_RATIO_MAX)
-                val = DCCPF_ACK_RATIO_MAX;
+        if (val > 0xFFFF)               /* RFC 4340, 11.3 */
+                val = 0xFFFF;
 
         if (val == dp->dccps_l_ack_ratio)
                 return;
@@ -110,77 +157,99 @@ static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
         dp->dccps_l_ack_ratio = val;
 }
 
+static void ccid2_change_srtt(struct ccid2_hc_tx_sock *hctx, long val)
+{
+        ccid2_pr_debug("change SRTT to %ld\n", val);
+        hctx->ccid2hctx_srtt = val;
+}
+
+static void ccid2_start_rto_timer(struct sock *sk);
+
 static void ccid2_hc_tx_rto_expire(unsigned long data)
 {
         struct sock *sk = (struct sock *)data;
         struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
-        const bool sender_was_blocked = ccid2_cwnd_network_limited(hctx);
+        long s;
 
         bh_lock_sock(sk);
         if (sock_owned_by_user(sk)) {
-                sk_reset_timer(sk, &hctx->rtotimer, jiffies + HZ / 5);
+                sk_reset_timer(sk, &hctx->ccid2hctx_rtotimer,
+                               jiffies + HZ / 5);
                 goto out;
         }
 
         ccid2_pr_debug("RTO_EXPIRE\n");
 
+        ccid2_hc_tx_check_sanity(hctx);
+
         /* back-off timer */
-        hctx->rto <<= 1;
-        if (hctx->rto > DCCP_RTO_MAX)
-                hctx->rto = DCCP_RTO_MAX;
+        hctx->ccid2hctx_rto <<= 1;
+
+        s = hctx->ccid2hctx_rto / HZ;
+        if (s > 60)
+                hctx->ccid2hctx_rto = 60 * HZ;
+
+        ccid2_start_rto_timer(sk);
 
         /* adjust pipe, cwnd etc */
-        hctx->ssthresh = hctx->cwnd / 2;
-        if (hctx->ssthresh < 2)
-                hctx->ssthresh = 2;
-        hctx->cwnd = 1;
-        hctx->pipe = 0;
+        hctx->ccid2hctx_ssthresh = hctx->ccid2hctx_cwnd / 2;
+        if (hctx->ccid2hctx_ssthresh < 2)
+                hctx->ccid2hctx_ssthresh = 2;
+        hctx->ccid2hctx_cwnd     = 1;
+        hctx->ccid2hctx_pipe     = 0;
 
         /* clear state about stuff we sent */
-        hctx->seqt = hctx->seqh;
-        hctx->packets_acked = 0;
+        hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqh;
+        hctx->ccid2hctx_packets_acked = 0;
 
         /* clear ack ratio state. */
-        hctx->rpseq    = 0;
-        hctx->rpdupack = -1;
+        hctx->ccid2hctx_rpseq    = 0;
+        hctx->ccid2hctx_rpdupack = -1;
         ccid2_change_l_ack_ratio(sk, 1);
-
-        /* if we were blocked before, we may now send cwnd=1 packet */
-        if (sender_was_blocked)
-                tasklet_schedule(&dccp_sk(sk)->dccps_xmitlet);
-        /* restart backed-off timer */
-        sk_reset_timer(sk, &hctx->rtotimer, jiffies + hctx->rto);
+        ccid2_hc_tx_check_sanity(hctx);
 out:
         bh_unlock_sock(sk);
         sock_put(sk);
 }
 
-static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len)
+static void ccid2_start_rto_timer(struct sock *sk)
+{
+        struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+
+        ccid2_pr_debug("setting RTO timeout=%ld\n", hctx->ccid2hctx_rto);
+
+        BUG_ON(timer_pending(&hctx->ccid2hctx_rtotimer));
+        sk_reset_timer(sk, &hctx->ccid2hctx_rtotimer,
+                       jiffies + hctx->ccid2hctx_rto);
+}
+
+static void ccid2_hc_tx_packet_sent(struct sock *sk, int more, unsigned int len)
 {
         struct dccp_sock *dp = dccp_sk(sk);
         struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
         struct ccid2_seq *next;
 
-        hctx->pipe++;
+        hctx->ccid2hctx_pipe++;
 
-        hctx->seqh->ccid2s_seq   = dp->dccps_gss;
-        hctx->seqh->ccid2s_acked = 0;
-        hctx->seqh->ccid2s_sent  = jiffies;
+        hctx->ccid2hctx_seqh->ccid2s_seq   = dp->dccps_gss;
+        hctx->ccid2hctx_seqh->ccid2s_acked = 0;
+        hctx->ccid2hctx_seqh->ccid2s_sent  = jiffies;
 
-        next = hctx->seqh->ccid2s_next;
+        next = hctx->ccid2hctx_seqh->ccid2s_next;
         /* check if we need to alloc more space */
-        if (next == hctx->seqt) {
+        if (next == hctx->ccid2hctx_seqt) {
                 if (ccid2_hc_tx_alloc_seq(hctx)) {
                         DCCP_CRIT("packet history - out of memory!");
                         /* FIXME: find a more graceful way to bail out */
                         return;
                 }
-                next = hctx->seqh->ccid2s_next;
-                BUG_ON(next == hctx->seqt);
+                next = hctx->ccid2hctx_seqh->ccid2s_next;
+                BUG_ON(next == hctx->ccid2hctx_seqt);
         }
-        hctx->seqh = next;
+        hctx->ccid2hctx_seqh = next;
 
-        ccid2_pr_debug("cwnd=%d pipe=%d\n", hctx->cwnd, hctx->pipe);
+        ccid2_pr_debug("cwnd=%d pipe=%d\n", hctx->ccid2hctx_cwnd,
+                       hctx->ccid2hctx_pipe);
 
         /*
          * FIXME: The code below is broken and the variables have been removed
@@ -203,12 +272,12 @@ static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len)
          */
 #if 0
         /* Ack Ratio.  Need to maintain a concept of how many windows we sent */
-        hctx->arsent++;
+        hctx->ccid2hctx_arsent++;
         /* We had an ack loss in this window... */
-        if (hctx->ackloss) {
-                if (hctx->arsent >= hctx->cwnd) {
-                        hctx->arsent  = 0;
-                        hctx->ackloss = 0;
+        if (hctx->ccid2hctx_ackloss) {
+                if (hctx->ccid2hctx_arsent >= hctx->ccid2hctx_cwnd) {
+                        hctx->ccid2hctx_arsent  = 0;
+                        hctx->ccid2hctx_ackloss = 0;
                 }
         } else {
                 /* No acks lost up to now... */
@@ -218,28 +287,28 @@ static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len)
                         int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio -
                                     dp->dccps_l_ack_ratio;
 
-                        denom = hctx->cwnd * hctx->cwnd / denom;
+                        denom = hctx->ccid2hctx_cwnd * hctx->ccid2hctx_cwnd / denom;
 
-                        if (hctx->arsent >= denom) {
+                        if (hctx->ccid2hctx_arsent >= denom) {
                                 ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1);
-                                hctx->arsent = 0;
+                                hctx->ccid2hctx_arsent = 0;
                         }
                 } else {
                         /* we can't increase ack ratio further [1] */
-                        hctx->arsent = 0; /* or maybe set it to cwnd*/
+                        hctx->ccid2hctx_arsent = 0; /* or maybe set it to cwnd*/
                 }
         }
 #endif
 
         /* setup RTO timer */
-        if (!timer_pending(&hctx->rtotimer))
-                sk_reset_timer(sk, &hctx->rtotimer, jiffies + hctx->rto);
+        if (!timer_pending(&hctx->ccid2hctx_rtotimer))
+                ccid2_start_rto_timer(sk);
 
 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
         do {
-                struct ccid2_seq *seqp = hctx->seqt;
+                struct ccid2_seq *seqp = hctx->ccid2hctx_seqt;
 
-                while (seqp != hctx->seqh) {
+                while (seqp != hctx->ccid2hctx_seqh) {
                         ccid2_pr_debug("out seq=%llu acked=%d time=%lu\n",
                                        (unsigned long long)seqp->ccid2s_seq,
                                        seqp->ccid2s_acked, seqp->ccid2s_sent);
@@ -247,158 +316,205 @@ static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len)
                 }
         } while (0);
         ccid2_pr_debug("=========\n");
+        ccid2_hc_tx_check_sanity(hctx);
 #endif
 }
 
-/**
- * ccid2_rtt_estimator - Sample RTT and compute RTO using RFC2988 algorithm
- * This code is almost identical with TCP's tcp_rtt_estimator(), since
- * - it has a higher sampling frequency (recommended by RFC 1323),
- * - the RTO does not collapse into RTT due to RTTVAR going towards zero,
- * - it is simple (cf. more complex proposals such as Eifel timer or research
- *   which suggests that the gain should be set according to window size),
- * - in tests it was found to work well with CCID2 [gerrit].
+/* XXX Lame code duplication!
+ * returns -1 if none was found.
+ * else returns the next offset to use in the function call.
  */
-static void ccid2_rtt_estimator(struct sock *sk, const long mrtt)
+static int ccid2_ackvector(struct sock *sk, struct sk_buff *skb, int offset,
+                           unsigned char **vec, unsigned char *veclen)
 {
-        struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
-        long m = mrtt ? : 1;
-
-        if (hctx->srtt == 0) {
-                /* First measurement m */
-                hctx->srtt = m << 3;
-                hctx->mdev = m << 1;
-
-                hctx->mdev_max = max(TCP_RTO_MIN, hctx->mdev);
-                hctx->rttvar   = hctx->mdev_max;
-                hctx->rtt_seq  = dccp_sk(sk)->dccps_gss;
-        } else {
-                /* Update scaled SRTT as SRTT += 1/8 * (m - SRTT) */
-                m -= (hctx->srtt >> 3);
-                hctx->srtt += m;
-
-                /* Similarly, update scaled mdev with regard to |m| */
-                if (m < 0) {
-                        m = -m;
-                        m -= (hctx->mdev >> 2);
+        const struct dccp_hdr *dh = dccp_hdr(skb);
+        unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
+        unsigned char *opt_ptr;
+        const unsigned char *opt_end = (unsigned char *)dh +
+                                        (dh->dccph_doff * 4);
+        unsigned char opt, len;
+        unsigned char *value;
+
+        BUG_ON(offset < 0);
+        options += offset;
+        opt_ptr = options;
+        if (opt_ptr >= opt_end)
+                return -1;
+
+        while (opt_ptr != opt_end) {
+                opt   = *opt_ptr++;
+                len   = 0;
+                value = NULL;
+
+                /* Check if this isn't a single byte option */
+                if (opt > DCCPO_MAX_RESERVED) {
+                        if (opt_ptr == opt_end)
+                                goto out_invalid_option;
+
+                        len = *opt_ptr++;
+                        if (len < 3)
+                                goto out_invalid_option;
                         /*
-                         * This neutralises RTO increase when RTT < SRTT - mdev
-                         * (see P. Sarolahti, A. Kuznetsov,"Congestion Control
-                         * in Linux TCP", USENIX 2002, pp. 49-62).
+                         * Remove the type and len fields, leaving
+                         * just the value size
                          */
-                        if (m > 0)
-                                m >>= 3;
-                } else {
-                        m -= (hctx->mdev >> 2);
-                }
-                hctx->mdev += m;
+                        len     -= 2;
+                        value   = opt_ptr;
+                        opt_ptr += len;
 
-                if (hctx->mdev > hctx->mdev_max) {
-                        hctx->mdev_max = hctx->mdev;
-                        if (hctx->mdev_max > hctx->rttvar)
-                                hctx->rttvar = hctx->mdev_max;
+                        if (opt_ptr > opt_end)
+                                goto out_invalid_option;
                 }
 
-                /*
-                 * Decay RTTVAR at most once per flight, exploiting that
-                 *  1) pipe <= cwnd <= Sequence_Window = W  (RFC 4340, 7.5.2)
-                 *  2) AWL = GSS-W+1 <= GAR <= GSS          (RFC 4340, 7.5.1)
-                 * GAR is a useful bound for FlightSize = pipe, AWL is probably
-                 * too low as it over-estimates pipe.
-                 */
-                if (after48(dccp_sk(sk)->dccps_gar, hctx->rtt_seq)) {
-                        if (hctx->mdev_max < hctx->rttvar)
-                                hctx->rttvar -= (hctx->rttvar -
-                                                 hctx->mdev_max) >> 2;
-                        hctx->rtt_seq  = dccp_sk(sk)->dccps_gss;
-                        hctx->mdev_max = TCP_RTO_MIN;
+                switch (opt) {
+                case DCCPO_ACK_VECTOR_0:
+                case DCCPO_ACK_VECTOR_1:
+                        *vec    = value;
+                        *veclen = len;
+                        return offset + (opt_ptr - options);
                 }
         }
 
-        /*
-         * Set RTO from SRTT and RTTVAR
-         * Clock granularity is ignored since the minimum error for RTTVAR is
-         * clamped to 50msec (corresponding to HZ=20). This leads to a minimum
-         * RTO of 200msec. This agrees with TCP and RFC 4341, 5.: "Because DCCP
-         * does not retransmit data, DCCP does not require TCP's recommended
-         * minimum timeout of one second".
-         */
-        hctx->rto = (hctx->srtt >> 3) + hctx->rttvar;
+        return -1;
 
-        if (hctx->rto > DCCP_RTO_MAX)
-                hctx->rto = DCCP_RTO_MAX;
+out_invalid_option:
+        DCCP_BUG("Invalid option - this should not happen (previous parsing)!");
+        return -1;
 }
 
-static void ccid2_new_ack(struct sock *sk, struct ccid2_seq *seqp,
-                          unsigned int *maxincr)
+static void ccid2_hc_tx_kill_rto_timer(struct sock *sk)
 {
         struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
 
-        if (hctx->cwnd < hctx->ssthresh) {
-                if (*maxincr > 0 && ++hctx->packets_acked == 2) {
-                        hctx->cwnd += 1;
-                        *maxincr   -= 1;
-                        hctx->packets_acked = 0;
-                }
-        } else if (++hctx->packets_acked >= hctx->cwnd) {
-                        hctx->cwnd += 1;
-                        hctx->packets_acked = 0;
-        }
-        /*
-         * FIXME: RTT is sampled several times per acknowledgment (for each
-         * entry in the Ack Vector), instead of once per Ack (as in TCP SACK).
-         * This causes the RTT to be over-estimated, since the older entries
-         * in the Ack Vector have earlier sending times.
-         * The cleanest solution is to not use the ccid2s_sent field at all
-         * and instead use DCCP timestamps - need to be resolved at some time.
-         */
-        ccid2_rtt_estimator(sk, jiffies - seqp->ccid2s_sent);
+        sk_stop_timer(sk, &hctx->ccid2hctx_rtotimer);
+        ccid2_pr_debug("deleted RTO timer\n");
 }
 
-static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
+static inline void ccid2_new_ack(struct sock *sk,
+                                 struct ccid2_seq *seqp,
+                                 unsigned int *maxincr)
 {
         struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
 
-        if (time_before(seqp->ccid2s_sent, hctx->last_cong)) {
-                ccid2_pr_debug("Multiple losses in an RTT---treating as one\n");
-                return;
+        if (hctx->ccid2hctx_cwnd < hctx->ccid2hctx_ssthresh) {
+                if (*maxincr > 0 && ++hctx->ccid2hctx_packets_acked == 2) {
+                        hctx->ccid2hctx_cwnd += 1;
+                        *maxincr             -= 1;
+                        hctx->ccid2hctx_packets_acked = 0;
+                }
+        } else if (++hctx->ccid2hctx_packets_acked >= hctx->ccid2hctx_cwnd) {
+                        hctx->ccid2hctx_cwnd += 1;
+                        hctx->ccid2hctx_packets_acked = 0;
         }
 
-        hctx->last_cong = jiffies;
+        /* update RTO */
+        if (hctx->ccid2hctx_srtt == -1 ||
+            time_after(jiffies, hctx->ccid2hctx_lastrtt + hctx->ccid2hctx_srtt)) {
+                unsigned long r = (long)jiffies - (long)seqp->ccid2s_sent;
+                int s;
+
+                /* first measurement */
+                if (hctx->ccid2hctx_srtt == -1) {
+                        ccid2_pr_debug("R: %lu Time=%lu seq=%llu\n",
+                                       r, jiffies,
+                                       (unsigned long long)seqp->ccid2s_seq);
+                        ccid2_change_srtt(hctx, r);
+                        hctx->ccid2hctx_rttvar = r >> 1;
+                } else {
+                        /* RTTVAR */
+                        long tmp = hctx->ccid2hctx_srtt - r;
+                        long srtt;
+
+                        if (tmp < 0)
+                                tmp *= -1;
+
+                        tmp >>= 2;
+                        hctx->ccid2hctx_rttvar *= 3;
+                        hctx->ccid2hctx_rttvar >>= 2;
+                        hctx->ccid2hctx_rttvar += tmp;
+
+                        /* SRTT */
+                        srtt = hctx->ccid2hctx_srtt;
+                        srtt *= 7;
+                        srtt >>= 3;
+                        tmp = r >> 3;
+                        srtt += tmp;
+                        ccid2_change_srtt(hctx, srtt);
+                }
+                s = hctx->ccid2hctx_rttvar << 2;
+                /* clock granularity is 1 when based on jiffies */
+                if (!s)
+                        s = 1;
+                hctx->ccid2hctx_rto = hctx->ccid2hctx_srtt + s;
+
+                /* must be at least a second */
+                s = hctx->ccid2hctx_rto / HZ;
+                /* DCCP doesn't require this [but I like it cuz my code sux] */
+#if 1
+                if (s < 1)
+                        hctx->ccid2hctx_rto = HZ;
+#endif
+                /* max 60 seconds */
+                if (s > 60)
+                        hctx->ccid2hctx_rto = HZ * 60;
 
-        hctx->cwnd     = hctx->cwnd / 2 ? : 1U;
-        hctx->ssthresh = max(hctx->cwnd, 2U);
+                hctx->ccid2hctx_lastrtt = jiffies;
 
-        /* Avoid spurious timeouts resulting from Ack Ratio > cwnd */
-        if (dccp_sk(sk)->dccps_l_ack_ratio > hctx->cwnd)
-                ccid2_change_l_ack_ratio(sk, hctx->cwnd);
+                ccid2_pr_debug("srtt: %ld rttvar: %ld rto: %ld (HZ=%d) R=%lu\n",
+                               hctx->ccid2hctx_srtt, hctx->ccid2hctx_rttvar,
+                               hctx->ccid2hctx_rto, HZ, r);
+        }
+
+        /* we got a new ack, so re-start RTO timer */
+        ccid2_hc_tx_kill_rto_timer(sk);
+        ccid2_start_rto_timer(sk);
 }
 
-static int ccid2_hc_tx_parse_options(struct sock *sk, u8 packet_type,
-                                     u8 option, u8 *optval, u8 optlen)
+static void ccid2_hc_tx_dec_pipe(struct sock *sk)
 {
         struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
 
-        switch (option) {
-        case DCCPO_ACK_VECTOR_0:
-        case DCCPO_ACK_VECTOR_1:
-                return dccp_ackvec_parsed_add(&hctx->av_chunks, optval, optlen,
-                                              option - DCCPO_ACK_VECTOR_0);
+        if (hctx->ccid2hctx_pipe == 0)
+                DCCP_BUG("pipe == 0");
+        else
+                hctx->ccid2hctx_pipe--;
+
+        if (hctx->ccid2hctx_pipe == 0)
+                ccid2_hc_tx_kill_rto_timer(sk);
+}
+
+static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
+{
+        struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+
+        if (time_before(seqp->ccid2s_sent, hctx->ccid2hctx_last_cong)) {
+                ccid2_pr_debug("Multiple losses in an RTT---treating as one\n");
+                return;
         }
-        return 0;
+
+        hctx->ccid2hctx_last_cong = jiffies;
+
+        hctx->ccid2hctx_cwnd     = hctx->ccid2hctx_cwnd / 2 ? : 1U;
+        hctx->ccid2hctx_ssthresh = max(hctx->ccid2hctx_cwnd, 2U);
+
+        /* Avoid spurious timeouts resulting from Ack Ratio > cwnd */
+        if (dccp_sk(sk)->dccps_l_ack_ratio > hctx->ccid2hctx_cwnd)
+                ccid2_change_l_ack_ratio(sk, hctx->ccid2hctx_cwnd);
 }
 
 static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 {
         struct dccp_sock *dp = dccp_sk(sk);
         struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
-        const bool sender_was_blocked = ccid2_cwnd_network_limited(hctx);
-        struct dccp_ackvec_parsed *avp;
         u64 ackno, seqno;
         struct ccid2_seq *seqp;
+        unsigned char *vector;
+        unsigned char veclen;
+        int offset = 0;
         int done = 0;
         unsigned int maxincr = 0;
 
+        ccid2_hc_tx_check_sanity(hctx);
         /* check reverse path congestion */
         seqno = DCCP_SKB_CB(skb)->dccpd_seq;
 
@@ -407,21 +523,21 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
          * -sorbo.
          */
         /* need to bootstrap */
-        if (hctx->rpdupack == -1) {
-                hctx->rpdupack = 0;
-                hctx->rpseq = seqno;
+        if (hctx->ccid2hctx_rpdupack == -1) {
+                hctx->ccid2hctx_rpdupack = 0;
+                hctx->ccid2hctx_rpseq = seqno;
         } else {
                 /* check if packet is consecutive */
-                if (dccp_delta_seqno(hctx->rpseq, seqno) == 1)
-                        hctx->rpseq = seqno;
+                if (dccp_delta_seqno(hctx->ccid2hctx_rpseq, seqno) == 1)
+                        hctx->ccid2hctx_rpseq = seqno;
                 /* it's a later packet */
-                else if (after48(seqno, hctx->rpseq)) {
-                        hctx->rpdupack++;
+                else if (after48(seqno, hctx->ccid2hctx_rpseq)) {
+                        hctx->ccid2hctx_rpdupack++;
 
                         /* check if we got enough dupacks */
-                        if (hctx->rpdupack >= NUMDUPACK) {
-                                hctx->rpdupack = -1; /* XXX lame */
-                                hctx->rpseq = 0;
+                        if (hctx->ccid2hctx_rpdupack >= NUMDUPACK) {
+                                hctx->ccid2hctx_rpdupack = -1; /* XXX lame */
+                                hctx->ccid2hctx_rpseq = 0;
 
                                 ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio);
                         }
@@ -429,22 +545,27 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
         }
 
         /* check forward path congestion */
-        if (dccp_packet_without_ack(skb))
+        /* still didn't send out new data packets */
+        if (hctx->ccid2hctx_seqh == hctx->ccid2hctx_seqt)
                 return;
 
-        /* still didn't send out new data packets */
-        if (hctx->seqh == hctx->seqt)
-                goto done;
+        switch (DCCP_SKB_CB(skb)->dccpd_type) {
+        case DCCP_PKT_ACK:
+        case DCCP_PKT_DATAACK:
+                break;
+        default:
+                return;
+        }
 
         ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
-        if (after48(ackno, hctx->high_ack))
-                hctx->high_ack = ackno;
+        if (after48(ackno, hctx->ccid2hctx_high_ack))
+                hctx->ccid2hctx_high_ack = ackno;
 
-        seqp = hctx->seqt;
+        seqp = hctx->ccid2hctx_seqt;
         while (before48(seqp->ccid2s_seq, ackno)) {
                 seqp = seqp->ccid2s_next;
-                if (seqp == hctx->seqh) {
-                        seqp = hctx->seqh->ccid2s_prev;
+                if (seqp == hctx->ccid2hctx_seqh) {
+                        seqp = hctx->ccid2hctx_seqh->ccid2s_prev;
                         break;
                 }
         }
@@ -454,26 +575,26 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
          * packets per acknowledgement. Rounding up avoids that cwnd is not
          * advanced when Ack Ratio is 1 and gives a slight edge otherwise.
          */
-        if (hctx->cwnd < hctx->ssthresh)
+        if (hctx->ccid2hctx_cwnd < hctx->ccid2hctx_ssthresh)
                 maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2);
 
         /* go through all ack vectors */
-        list_for_each_entry(avp, &hctx->av_chunks, node) {
+        while ((offset = ccid2_ackvector(sk, skb, offset,
+                                         &vector, &veclen)) != -1) {
                 /* go through this ack vector */
-                for (; avp->len--; avp->vec++) {
-                        u64 ackno_end_rl = SUB48(ackno,
-                                                 dccp_ackvec_runlen(avp->vec));
+                while (veclen--) {
+                        const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
+                        u64 ackno_end_rl = SUB48(ackno, rl);
 
-                        ccid2_pr_debug("ackvec %llu |%u,%u|\n",
+                        ccid2_pr_debug("ackvec start:%llu end:%llu\n",
                                        (unsigned long long)ackno,
-                                       dccp_ackvec_state(avp->vec) >> 6,
-                                       dccp_ackvec_runlen(avp->vec));
+                                       (unsigned long long)ackno_end_rl);
                         /* if the seqno we are analyzing is larger than the
                          * current ackno, then move towards the tail of our
                          * seqnos.
                          */
                         while (after48(seqp->ccid2s_seq, ackno)) {
-                                if (seqp == hctx->seqt) {
+                                if (seqp == hctx->ccid2hctx_seqt) {
                                         done = 1;
                                         break;
                                 }
@@ -486,24 +607,26 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
                          * run length
                          */
                         while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) {
-                                const u8 state = dccp_ackvec_state(avp->vec);
+                                const u8 state = *vector &
+                                                 DCCP_ACKVEC_STATE_MASK;
 
                                 /* new packet received or marked */
-                                if (state != DCCPAV_NOT_RECEIVED &&
+                                if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED &&
                                     !seqp->ccid2s_acked) {
-                                        if (state == DCCPAV_ECN_MARKED)
+                                        if (state ==
+                                            DCCP_ACKVEC_STATE_ECN_MARKED) {
                                                 ccid2_congestion_event(sk,
                                                                        seqp);
-                                        else
+                                        } else
                                                 ccid2_new_ack(sk, seqp,
                                                               &maxincr);
 
                                         seqp->ccid2s_acked = 1;
                                         ccid2_pr_debug("Got ack for %llu\n",
                                                        (unsigned long long)seqp->ccid2s_seq);
-                                        hctx->pipe--;
+                                        ccid2_hc_tx_dec_pipe(sk);
                                 }
-                                if (seqp == hctx->seqt) {
+                                if (seqp == hctx->ccid2hctx_seqt) {
                                         done = 1;
                                         break;
                                 }
@@ -513,6 +636,7 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
                                 break;
 
                         ackno = SUB48(ackno_end_rl, 1);
+                        vector++;
                 }
                 if (done)
                         break;
@@ -521,11 +645,11 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
         /* The state about what is acked should be correct now
          * Check for NUMDUPACK
          */
-        seqp = hctx->seqt;
-        while (before48(seqp->ccid2s_seq, hctx->high_ack)) {
+        seqp = hctx->ccid2hctx_seqt;
+        while (before48(seqp->ccid2s_seq, hctx->ccid2hctx_high_ack)) {
                 seqp = seqp->ccid2s_next;
-                if (seqp == hctx->seqh) {
-                        seqp = hctx->seqh->ccid2s_prev;
+                if (seqp == hctx->ccid2hctx_seqh) {
+                        seqp = hctx->ccid2hctx_seqh->ccid2s_prev;
                         break;
                 }
         }
@@ -536,7 +660,7 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
                         if (done == NUMDUPACK)
                                 break;
                 }
-                if (seqp == hctx->seqt)
+                if (seqp == hctx->ccid2hctx_seqt)
                         break;
                 seqp = seqp->ccid2s_prev;
         }
@@ -557,34 +681,25 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
                                  * one ack vector.
                                  */
                                 ccid2_congestion_event(sk, seqp);
-                                hctx->pipe--;
+                                ccid2_hc_tx_dec_pipe(sk);
                         }
-                        if (seqp == hctx->seqt)
+                        if (seqp == hctx->ccid2hctx_seqt)
                                 break;
                         seqp = seqp->ccid2s_prev;
                 }
 
-                hctx->seqt = last_acked;
+                hctx->ccid2hctx_seqt = last_acked;
         }
 
         /* trim acked packets in tail */
-        while (hctx->seqt != hctx->seqh) {
-                if (!hctx->seqt->ccid2s_acked)
+        while (hctx->ccid2hctx_seqt != hctx->ccid2hctx_seqh) {
+                if (!hctx->ccid2hctx_seqt->ccid2s_acked)
                         break;
 
-                hctx->seqt = hctx->seqt->ccid2s_next;
+                hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqt->ccid2s_next;
         }
 
-        /* restart RTO timer if not all outstanding data has been acked */
-        if (hctx->pipe == 0)
-                sk_stop_timer(sk, &hctx->rtotimer);
-        else
-                sk_reset_timer(sk, &hctx->rtotimer, jiffies + hctx->rto);
-done:
-        /* check if incoming Acks allow pending packets to be sent */
-        if (sender_was_blocked && !ccid2_cwnd_network_limited(hctx))
-                tasklet_schedule(&dccp_sk(sk)->dccps_xmitlet);
-        dccp_ackvec_parsed_cleanup(&hctx->av_chunks);
+        ccid2_hc_tx_check_sanity(hctx);
 }
 
 static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
@@ -594,13 +709,17 @@ static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
         u32 max_ratio;
 
         /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */
-        hctx->ssthresh = ~0U;
+        hctx->ccid2hctx_ssthresh  = ~0U;
 
-        /* Use larger initial windows (RFC 3390, rfc2581bis) */
-        hctx->cwnd = rfc3390_bytes_to_packets(dp->dccps_mss_cache);
+        /*
+         * RFC 4341, 5: "The cwnd parameter is initialized to at most four
+         * packets for new connections, following the rules from [RFC3390]".
+         * We need to convert the bytes of RFC3390 into the packets of RFC 4341.
+         */
+        hctx->ccid2hctx_cwnd = clamp(4380U / dp->dccps_mss_cache, 2U, 4U);
 
         /* Make sure that Ack Ratio is enabled and within bounds. */
-        max_ratio = DIV_ROUND_UP(hctx->cwnd, 2);
+        max_ratio = DIV_ROUND_UP(hctx->ccid2hctx_cwnd, 2);
         if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio)
                 dp->dccps_l_ack_ratio = max_ratio;
 
@@ -608,11 +727,15 @@ static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
         if (ccid2_hc_tx_alloc_seq(hctx))
                 return -ENOMEM;
 
-        hctx->rto       = DCCP_TIMEOUT_INIT;
-        hctx->rpdupack  = -1;
-        hctx->last_cong = jiffies;
-        setup_timer(&hctx->rtotimer, ccid2_hc_tx_rto_expire, (unsigned long)sk);
-        INIT_LIST_HEAD(&hctx->av_chunks);
+        hctx->ccid2hctx_rto      = 3 * HZ;
+        ccid2_change_srtt(hctx, -1);
+        hctx->ccid2hctx_rttvar   = -1;
+        hctx->ccid2hctx_rpdupack = -1;
+        hctx->ccid2hctx_last_cong = jiffies;
+        setup_timer(&hctx->ccid2hctx_rtotimer, ccid2_hc_tx_rto_expire,
+                        (unsigned long)sk);
+
+        ccid2_hc_tx_check_sanity(hctx);
         return 0;
 }
 
@@ -621,11 +744,11 @@ static void ccid2_hc_tx_exit(struct sock *sk)
         struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
         int i;
 
-        sk_stop_timer(sk, &hctx->rtotimer);
+        ccid2_hc_tx_kill_rto_timer(sk);
 
-        for (i = 0; i < hctx->seqbufc; i++)
-                kfree(hctx->seqbuf[i]);
-        hctx->seqbufc = 0;
+        for (i = 0; i < hctx->ccid2hctx_seqbufc; i++)
+                kfree(hctx->ccid2hctx_seqbuf[i]);
+        hctx->ccid2hctx_seqbufc = 0;
 }
 
 static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
@@ -636,28 +759,27 @@ static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
         switch (DCCP_SKB_CB(skb)->dccpd_type) {
         case DCCP_PKT_DATA:
         case DCCP_PKT_DATAACK:
-                hcrx->data++;
-                if (hcrx->data >= dp->dccps_r_ack_ratio) {
+                hcrx->ccid2hcrx_data++;
+                if (hcrx->ccid2hcrx_data >= dp->dccps_r_ack_ratio) {
                         dccp_send_ack(sk);
-                        hcrx->data = 0;
+                        hcrx->ccid2hcrx_data = 0;
                 }
                 break;
         }
 }
 
 static struct ccid_operations ccid2 = {
-        .ccid_id                  = DCCPC_CCID2,
-        .ccid_name                = "TCP-like",
-        .ccid_owner               = THIS_MODULE,
-        .ccid_hc_tx_obj_size      = sizeof(struct ccid2_hc_tx_sock),
-        .ccid_hc_tx_init          = ccid2_hc_tx_init,
-        .ccid_hc_tx_exit          = ccid2_hc_tx_exit,
-        .ccid_hc_tx_send_packet   = ccid2_hc_tx_send_packet,
-        .ccid_hc_tx_packet_sent   = ccid2_hc_tx_packet_sent,
-        .ccid_hc_tx_parse_options = ccid2_hc_tx_parse_options,
-        .ccid_hc_tx_packet_recv   = ccid2_hc_tx_packet_recv,
-        .ccid_hc_rx_obj_size      = sizeof(struct ccid2_hc_rx_sock),
-        .ccid_hc_rx_packet_recv   = ccid2_hc_rx_packet_recv,
+        .ccid_id                = DCCPC_CCID2,
+        .ccid_name              = "TCP-like",
+        .ccid_owner             = THIS_MODULE,
+        .ccid_hc_tx_obj_size    = sizeof(struct ccid2_hc_tx_sock),
+        .ccid_hc_tx_init        = ccid2_hc_tx_init,
+        .ccid_hc_tx_exit        = ccid2_hc_tx_exit,
+        .ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet,
+        .ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent,
+        .ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv,
+        .ccid_hc_rx_obj_size    = sizeof(struct ccid2_hc_rx_sock),
+        .ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv,
 };
 
 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG