v4.19.13 snapshot.
diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
new file mode 100644
index 0000000..842a9c7
--- /dev/null
+++ b/net/dccp/ccids/ccid2.c
@@ -0,0 +1,801 @@
+/*
+ * Copyright (c) 2005, 2006 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
+ *
+ * Changes to meet Linux coding standards, and DCCP infrastructure fixes.
+ *
+ * Copyright (c) 2006 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/*
+ * This implementation should follow RFC 4341
+ */
+#include <linux/slab.h>
+#include "../feat.h"
+#include "ccid2.h"
+
+
+#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
+static bool ccid2_debug;
+#define ccid2_pr_debug(format, a...) DCCP_PR_DEBUG(ccid2_debug, format, ##a)
+#else
+#define ccid2_pr_debug(format, a...)
+#endif
+
+static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hc)
+{
+ struct ccid2_seq *seqp;
+ int i;
+
+ /* check if we have space to preserve the pointer to the buffer */
+ if (hc->tx_seqbufc >= (sizeof(hc->tx_seqbuf) /
+ sizeof(struct ccid2_seq *)))
+ return -ENOMEM;
+
+ /* allocate buffer and initialize linked list */
+ seqp = kmalloc_array(CCID2_SEQBUF_LEN, sizeof(struct ccid2_seq),
+ gfp_any());
+ if (seqp == NULL)
+ return -ENOMEM;
+
+ for (i = 0; i < (CCID2_SEQBUF_LEN - 1); i++) {
+ seqp[i].ccid2s_next = &seqp[i + 1];
+ seqp[i + 1].ccid2s_prev = &seqp[i];
+ }
+ seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = seqp;
+ seqp->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
+
+ /* This is the first allocation. Initiate the head and tail. */
+ if (hc->tx_seqbufc == 0)
+ hc->tx_seqh = hc->tx_seqt = seqp;
+ else {
+ /* link the existing list with the one we just created */
+ hc->tx_seqh->ccid2s_next = seqp;
+ seqp->ccid2s_prev = hc->tx_seqh;
+
+ hc->tx_seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
+ seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hc->tx_seqt;
+ }
+
+ /* store the original pointer to the buffer so we can free it */
+ hc->tx_seqbuf[hc->tx_seqbufc] = seqp;
+ hc->tx_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;
+}
+
+static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
+{
+ u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->tx_cwnd, 2);
+
+ /*
+ * Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from
+ * RFC 4341, 6.1.2. We ignore the statement that Ack Ratio 2 is always
+ * acceptable since this causes starvation/deadlock whenever cwnd < 2.
+ * The same problem arises when Ack Ratio is 0 (ie. Ack Ratio disabled).
+ */
+ if (val == 0 || val > max_ratio) {
+ DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio);
+ val = max_ratio;
+ }
+ dccp_feat_signal_nn_change(sk, DCCPF_ACK_RATIO,
+ min_t(u32, val, DCCPF_ACK_RATIO_MAX));
+}
+
+static void ccid2_check_l_ack_ratio(struct sock *sk)
+{
+ struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
+
+ /*
+ * After a loss, idle period, application limited period, or RTO we
+ * need to check that the ack ratio is still less than the congestion
+ * window. Otherwise, we will send an entire congestion window of
+ * packets and got no response because we haven't sent ack ratio
+ * packets yet.
+ * If the ack ratio does need to be reduced, we reduce it to half of
+ * the congestion window (or 1 if that's zero) instead of to the
+ * congestion window. This prevents problems if one ack is lost.
+ */
+ if (dccp_feat_nn_get(sk, DCCPF_ACK_RATIO) > hc->tx_cwnd)
+ ccid2_change_l_ack_ratio(sk, hc->tx_cwnd/2 ? : 1U);
+}
+
+static void ccid2_change_l_seq_window(struct sock *sk, u64 val)
+{
+ dccp_feat_signal_nn_change(sk, DCCPF_SEQUENCE_WINDOW,
+ clamp_val(val, DCCPF_SEQ_WMIN,
+ DCCPF_SEQ_WMAX));
+}
+
+static void dccp_tasklet_schedule(struct sock *sk)
+{
+ struct tasklet_struct *t = &dccp_sk(sk)->dccps_xmitlet;
+
+ if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) {
+ sock_hold(sk);
+ __tasklet_schedule(t);
+ }
+}
+
+static void ccid2_hc_tx_rto_expire(struct timer_list *t)
+{
+ struct ccid2_hc_tx_sock *hc = from_timer(hc, t, tx_rtotimer);
+ struct sock *sk = hc->sk;
+ const bool sender_was_blocked = ccid2_cwnd_network_limited(hc);
+
+ bh_lock_sock(sk);
+ if (sock_owned_by_user(sk)) {
+ sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + HZ / 5);
+ goto out;
+ }
+
+ ccid2_pr_debug("RTO_EXPIRE\n");
+
+ if (sk->sk_state == DCCP_CLOSED)
+ goto out;
+
+ /* back-off timer */
+ hc->tx_rto <<= 1;
+ if (hc->tx_rto > DCCP_RTO_MAX)
+ hc->tx_rto = DCCP_RTO_MAX;
+
+ /* adjust pipe, cwnd etc */
+ hc->tx_ssthresh = hc->tx_cwnd / 2;
+ if (hc->tx_ssthresh < 2)
+ hc->tx_ssthresh = 2;
+ hc->tx_cwnd = 1;
+ hc->tx_pipe = 0;
+
+ /* clear state about stuff we sent */
+ hc->tx_seqt = hc->tx_seqh;
+ hc->tx_packets_acked = 0;
+
+ /* clear ack ratio state. */
+ hc->tx_rpseq = 0;
+ hc->tx_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)
+ dccp_tasklet_schedule(sk);
+ /* restart backed-off timer */
+ sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto);
+out:
+ bh_unlock_sock(sk);
+ sock_put(sk);
+}
+
+/*
+ * Congestion window validation (RFC 2861).
+ */
+static bool ccid2_do_cwv = true;
+module_param(ccid2_do_cwv, bool, 0644);
+MODULE_PARM_DESC(ccid2_do_cwv, "Perform RFC2861 Congestion Window Validation");
+
+/**
+ * ccid2_update_used_window - Track how much of cwnd is actually used
+ * This is done in addition to CWV. The sender needs to have an idea of how many
+ * packets may be in flight, to set the local Sequence Window value accordingly
+ * (RFC 4340, 7.5.2). The CWV mechanism is exploited to keep track of the
+ * maximum-used window. We use an EWMA low-pass filter to filter out noise.
+ */
+static void ccid2_update_used_window(struct ccid2_hc_tx_sock *hc, u32 new_wnd)
+{
+ hc->tx_expected_wnd = (3 * hc->tx_expected_wnd + new_wnd) / 4;
+}
+
+/* This borrows the code of tcp_cwnd_application_limited() */
+static void ccid2_cwnd_application_limited(struct sock *sk, const u32 now)
+{
+ struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
+ /* don't reduce cwnd below the initial window (IW) */
+ u32 init_win = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache),
+ win_used = max(hc->tx_cwnd_used, init_win);
+
+ if (win_used < hc->tx_cwnd) {
+ hc->tx_ssthresh = max(hc->tx_ssthresh,
+ (hc->tx_cwnd >> 1) + (hc->tx_cwnd >> 2));
+ hc->tx_cwnd = (hc->tx_cwnd + win_used) >> 1;
+ }
+ hc->tx_cwnd_used = 0;
+ hc->tx_cwnd_stamp = now;
+
+ ccid2_check_l_ack_ratio(sk);
+}
+
+/* This borrows the code of tcp_cwnd_restart() */
+static void ccid2_cwnd_restart(struct sock *sk, const u32 now)
+{
+ struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
+ u32 cwnd = hc->tx_cwnd, restart_cwnd,
+ iwnd = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache);
+ s32 delta = now - hc->tx_lsndtime;
+
+ hc->tx_ssthresh = max(hc->tx_ssthresh, (cwnd >> 1) + (cwnd >> 2));
+
+ /* don't reduce cwnd below the initial window (IW) */
+ restart_cwnd = min(cwnd, iwnd);
+
+ while ((delta -= hc->tx_rto) >= 0 && cwnd > restart_cwnd)
+ cwnd >>= 1;
+ hc->tx_cwnd = max(cwnd, restart_cwnd);
+ hc->tx_cwnd_stamp = now;
+ hc->tx_cwnd_used = 0;
+
+ ccid2_check_l_ack_ratio(sk);
+}
+
+static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len)
+{
+ struct dccp_sock *dp = dccp_sk(sk);
+ struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
+ const u32 now = ccid2_jiffies32;
+ struct ccid2_seq *next;
+
+ /* slow-start after idle periods (RFC 2581, RFC 2861) */
+ if (ccid2_do_cwv && !hc->tx_pipe &&
+ (s32)(now - hc->tx_lsndtime) >= hc->tx_rto)
+ ccid2_cwnd_restart(sk, now);
+
+ hc->tx_lsndtime = now;
+ hc->tx_pipe += 1;
+
+ /* see whether cwnd was fully used (RFC 2861), update expected window */
+ if (ccid2_cwnd_network_limited(hc)) {
+ ccid2_update_used_window(hc, hc->tx_cwnd);
+ hc->tx_cwnd_used = 0;
+ hc->tx_cwnd_stamp = now;
+ } else {
+ if (hc->tx_pipe > hc->tx_cwnd_used)
+ hc->tx_cwnd_used = hc->tx_pipe;
+
+ ccid2_update_used_window(hc, hc->tx_cwnd_used);
+
+ if (ccid2_do_cwv && (s32)(now - hc->tx_cwnd_stamp) >= hc->tx_rto)
+ ccid2_cwnd_application_limited(sk, now);
+ }
+
+ hc->tx_seqh->ccid2s_seq = dp->dccps_gss;
+ hc->tx_seqh->ccid2s_acked = 0;
+ hc->tx_seqh->ccid2s_sent = now;
+
+ next = hc->tx_seqh->ccid2s_next;
+ /* check if we need to alloc more space */
+ if (next == hc->tx_seqt) {
+ if (ccid2_hc_tx_alloc_seq(hc)) {
+ DCCP_CRIT("packet history - out of memory!");
+ /* FIXME: find a more graceful way to bail out */
+ return;
+ }
+ next = hc->tx_seqh->ccid2s_next;
+ BUG_ON(next == hc->tx_seqt);
+ }
+ hc->tx_seqh = next;
+
+ ccid2_pr_debug("cwnd=%d pipe=%d\n", hc->tx_cwnd, hc->tx_pipe);
+
+ /*
+ * FIXME: The code below is broken and the variables have been removed
+ * from the socket struct. The `ackloss' variable was always set to 0,
+ * and with arsent there are several problems:
+ * (i) it doesn't just count the number of Acks, but all sent packets;
+ * (ii) it is expressed in # of packets, not # of windows, so the
+ * comparison below uses the wrong formula: Appendix A of RFC 4341
+ * comes up with the number K = cwnd / (R^2 - R) of consecutive windows
+ * of data with no lost or marked Ack packets. If arsent were the # of
+ * consecutive Acks received without loss, then Ack Ratio needs to be
+ * decreased by 1 when
+ * arsent >= K * cwnd / R = cwnd^2 / (R^3 - R^2)
+ * where cwnd / R is the number of Acks received per window of data
+ * (cf. RFC 4341, App. A). The problems are that
+ * - arsent counts other packets as well;
+ * - the comparison uses a formula different from RFC 4341;
+ * - computing a cubic/quadratic equation each time is too complicated.
+ * Hence a different algorithm is needed.
+ */
+#if 0
+ /* Ack Ratio. Need to maintain a concept of how many windows we sent */
+ hc->tx_arsent++;
+ /* We had an ack loss in this window... */
+ if (hc->tx_ackloss) {
+ if (hc->tx_arsent >= hc->tx_cwnd) {
+ hc->tx_arsent = 0;
+ hc->tx_ackloss = 0;
+ }
+ } else {
+ /* No acks lost up to now... */
+ /* decrease ack ratio if enough packets were sent */
+ if (dp->dccps_l_ack_ratio > 1) {
+ /* XXX don't calculate denominator each time */
+ int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio -
+ dp->dccps_l_ack_ratio;
+
+ denom = hc->tx_cwnd * hc->tx_cwnd / denom;
+
+ if (hc->tx_arsent >= denom) {
+ ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1);
+ hc->tx_arsent = 0;
+ }
+ } else {
+ /* we can't increase ack ratio further [1] */
+ hc->tx_arsent = 0; /* or maybe set it to cwnd*/
+ }
+ }
+#endif
+
+ sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto);
+
+#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
+ do {
+ struct ccid2_seq *seqp = hc->tx_seqt;
+
+ while (seqp != hc->tx_seqh) {
+ ccid2_pr_debug("out seq=%llu acked=%d time=%u\n",
+ (unsigned long long)seqp->ccid2s_seq,
+ seqp->ccid2s_acked, seqp->ccid2s_sent);
+ seqp = seqp->ccid2s_next;
+ }
+ } while (0);
+ ccid2_pr_debug("=========\n");
+#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].
+ */
+static void ccid2_rtt_estimator(struct sock *sk, const long mrtt)
+{
+ struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
+ long m = mrtt ? : 1;
+
+ if (hc->tx_srtt == 0) {
+ /* First measurement m */
+ hc->tx_srtt = m << 3;
+ hc->tx_mdev = m << 1;
+
+ hc->tx_mdev_max = max(hc->tx_mdev, tcp_rto_min(sk));
+ hc->tx_rttvar = hc->tx_mdev_max;
+
+ hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss;
+ } else {
+ /* Update scaled SRTT as SRTT += 1/8 * (m - SRTT) */
+ m -= (hc->tx_srtt >> 3);
+ hc->tx_srtt += m;
+
+ /* Similarly, update scaled mdev with regard to |m| */
+ if (m < 0) {
+ m = -m;
+ m -= (hc->tx_mdev >> 2);
+ /*
+ * This neutralises RTO increase when RTT < SRTT - mdev
+ * (see P. Sarolahti, A. Kuznetsov,"Congestion Control
+ * in Linux TCP", USENIX 2002, pp. 49-62).
+ */
+ if (m > 0)
+ m >>= 3;
+ } else {
+ m -= (hc->tx_mdev >> 2);
+ }
+ hc->tx_mdev += m;
+
+ if (hc->tx_mdev > hc->tx_mdev_max) {
+ hc->tx_mdev_max = hc->tx_mdev;
+ if (hc->tx_mdev_max > hc->tx_rttvar)
+ hc->tx_rttvar = hc->tx_mdev_max;
+ }
+
+ /*
+ * 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 here, as it over-estimates pipe.
+ */
+ if (after48(dccp_sk(sk)->dccps_gar, hc->tx_rtt_seq)) {
+ if (hc->tx_mdev_max < hc->tx_rttvar)
+ hc->tx_rttvar -= (hc->tx_rttvar -
+ hc->tx_mdev_max) >> 2;
+ hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss;
+ hc->tx_mdev_max = tcp_rto_min(sk);
+ }
+ }
+
+ /*
+ * Set RTO from SRTT and RTTVAR
+ * As in TCP, 4 * RTTVAR >= TCP_RTO_MIN, giving a minimum RTO of 200 ms.
+ * This agrees with RFC 4341, 5:
+ * "Because DCCP does not retransmit data, DCCP does not require
+ * TCP's recommended minimum timeout of one second".
+ */
+ hc->tx_rto = (hc->tx_srtt >> 3) + hc->tx_rttvar;
+
+ if (hc->tx_rto > DCCP_RTO_MAX)
+ hc->tx_rto = DCCP_RTO_MAX;
+}
+
+static void ccid2_new_ack(struct sock *sk, struct ccid2_seq *seqp,
+ unsigned int *maxincr)
+{
+ struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
+ struct dccp_sock *dp = dccp_sk(sk);
+ int r_seq_used = hc->tx_cwnd / dp->dccps_l_ack_ratio;
+
+ if (hc->tx_cwnd < dp->dccps_l_seq_win &&
+ r_seq_used < dp->dccps_r_seq_win) {
+ if (hc->tx_cwnd < hc->tx_ssthresh) {
+ if (*maxincr > 0 && ++hc->tx_packets_acked >= 2) {
+ hc->tx_cwnd += 1;
+ *maxincr -= 1;
+ hc->tx_packets_acked = 0;
+ }
+ } else if (++hc->tx_packets_acked >= hc->tx_cwnd) {
+ hc->tx_cwnd += 1;
+ hc->tx_packets_acked = 0;
+ }
+ }
+
+ /*
+ * Adjust the local sequence window and the ack ratio to allow about
+ * 5 times the number of packets in the network (RFC 4340 7.5.2)
+ */
+ if (r_seq_used * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_r_seq_win)
+ ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio * 2);
+ else if (r_seq_used * CCID2_WIN_CHANGE_FACTOR < dp->dccps_r_seq_win/2)
+ ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio / 2 ? : 1U);
+
+ if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_l_seq_win)
+ ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win * 2);
+ else if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR < dp->dccps_l_seq_win/2)
+ ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win / 2);
+
+ /*
+ * 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: requires changes in other places.
+ */
+ ccid2_rtt_estimator(sk, ccid2_jiffies32 - seqp->ccid2s_sent);
+}
+
+static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
+{
+ struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
+
+ if ((s32)(seqp->ccid2s_sent - hc->tx_last_cong) < 0) {
+ ccid2_pr_debug("Multiple losses in an RTT---treating as one\n");
+ return;
+ }
+
+ hc->tx_last_cong = ccid2_jiffies32;
+
+ hc->tx_cwnd = hc->tx_cwnd / 2 ? : 1U;
+ hc->tx_ssthresh = max(hc->tx_cwnd, 2U);
+
+ ccid2_check_l_ack_ratio(sk);
+}
+
+static int ccid2_hc_tx_parse_options(struct sock *sk, u8 packet_type,
+ u8 option, u8 *optval, u8 optlen)
+{
+ struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
+
+ switch (option) {
+ case DCCPO_ACK_VECTOR_0:
+ case DCCPO_ACK_VECTOR_1:
+ return dccp_ackvec_parsed_add(&hc->tx_av_chunks, optval, optlen,
+ option - DCCPO_ACK_VECTOR_0);
+ }
+ return 0;
+}
+
+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 *hc = ccid2_hc_tx_sk(sk);
+ const bool sender_was_blocked = ccid2_cwnd_network_limited(hc);
+ struct dccp_ackvec_parsed *avp;
+ u64 ackno, seqno;
+ struct ccid2_seq *seqp;
+ int done = 0;
+ unsigned int maxincr = 0;
+
+ /* check reverse path congestion */
+ seqno = DCCP_SKB_CB(skb)->dccpd_seq;
+
+ /* XXX this whole "algorithm" is broken. Need to fix it to keep track
+ * of the seqnos of the dupacks so that rpseq and rpdupack are correct
+ * -sorbo.
+ */
+ /* need to bootstrap */
+ if (hc->tx_rpdupack == -1) {
+ hc->tx_rpdupack = 0;
+ hc->tx_rpseq = seqno;
+ } else {
+ /* check if packet is consecutive */
+ if (dccp_delta_seqno(hc->tx_rpseq, seqno) == 1)
+ hc->tx_rpseq = seqno;
+ /* it's a later packet */
+ else if (after48(seqno, hc->tx_rpseq)) {
+ hc->tx_rpdupack++;
+
+ /* check if we got enough dupacks */
+ if (hc->tx_rpdupack >= NUMDUPACK) {
+ hc->tx_rpdupack = -1; /* XXX lame */
+ hc->tx_rpseq = 0;
+#ifdef __CCID2_COPES_GRACEFULLY_WITH_ACK_CONGESTION_CONTROL__
+ /*
+ * FIXME: Ack Congestion Control is broken; in
+ * the current state instabilities occurred with
+ * Ack Ratios greater than 1; causing hang-ups
+ * and long RTO timeouts. This needs to be fixed
+ * before opening up dynamic changes. -- gerrit
+ */
+ ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio);
+#endif
+ }
+ }
+ }
+
+ /* check forward path congestion */
+ if (dccp_packet_without_ack(skb))
+ return;
+
+ /* still didn't send out new data packets */
+ if (hc->tx_seqh == hc->tx_seqt)
+ goto done;
+
+ ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
+ if (after48(ackno, hc->tx_high_ack))
+ hc->tx_high_ack = ackno;
+
+ seqp = hc->tx_seqt;
+ while (before48(seqp->ccid2s_seq, ackno)) {
+ seqp = seqp->ccid2s_next;
+ if (seqp == hc->tx_seqh) {
+ seqp = hc->tx_seqh->ccid2s_prev;
+ break;
+ }
+ }
+
+ /*
+ * In slow-start, cwnd can increase up to a maximum of Ack Ratio/2
+ * packets per acknowledgement. Rounding up avoids that cwnd is not
+ * advanced when Ack Ratio is 1 and gives a slight edge otherwise.
+ */
+ if (hc->tx_cwnd < hc->tx_ssthresh)
+ maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2);
+
+ /* go through all ack vectors */
+ list_for_each_entry(avp, &hc->tx_av_chunks, node) {
+ /* go through this ack vector */
+ for (; avp->len--; avp->vec++) {
+ u64 ackno_end_rl = SUB48(ackno,
+ dccp_ackvec_runlen(avp->vec));
+
+ ccid2_pr_debug("ackvec %llu |%u,%u|\n",
+ (unsigned long long)ackno,
+ dccp_ackvec_state(avp->vec) >> 6,
+ dccp_ackvec_runlen(avp->vec));
+ /* 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 == hc->tx_seqt) {
+ done = 1;
+ break;
+ }
+ seqp = seqp->ccid2s_prev;
+ }
+ if (done)
+ break;
+
+ /* check all seqnos in the range of the vector
+ * run length
+ */
+ while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) {
+ const u8 state = dccp_ackvec_state(avp->vec);
+
+ /* new packet received or marked */
+ if (state != DCCPAV_NOT_RECEIVED &&
+ !seqp->ccid2s_acked) {
+ if (state == DCCPAV_ECN_MARKED)
+ ccid2_congestion_event(sk,
+ seqp);
+ 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);
+ hc->tx_pipe--;
+ }
+ if (seqp == hc->tx_seqt) {
+ done = 1;
+ break;
+ }
+ seqp = seqp->ccid2s_prev;
+ }
+ if (done)
+ break;
+
+ ackno = SUB48(ackno_end_rl, 1);
+ }
+ if (done)
+ break;
+ }
+
+ /* The state about what is acked should be correct now
+ * Check for NUMDUPACK
+ */
+ seqp = hc->tx_seqt;
+ while (before48(seqp->ccid2s_seq, hc->tx_high_ack)) {
+ seqp = seqp->ccid2s_next;
+ if (seqp == hc->tx_seqh) {
+ seqp = hc->tx_seqh->ccid2s_prev;
+ break;
+ }
+ }
+ done = 0;
+ while (1) {
+ if (seqp->ccid2s_acked) {
+ done++;
+ if (done == NUMDUPACK)
+ break;
+ }
+ if (seqp == hc->tx_seqt)
+ break;
+ seqp = seqp->ccid2s_prev;
+ }
+
+ /* If there are at least 3 acknowledgements, anything unacknowledged
+ * below the last sequence number is considered lost
+ */
+ if (done == NUMDUPACK) {
+ struct ccid2_seq *last_acked = seqp;
+
+ /* check for lost packets */
+ while (1) {
+ if (!seqp->ccid2s_acked) {
+ ccid2_pr_debug("Packet lost: %llu\n",
+ (unsigned long long)seqp->ccid2s_seq);
+ /* XXX need to traverse from tail -> head in
+ * order to detect multiple congestion events in
+ * one ack vector.
+ */
+ ccid2_congestion_event(sk, seqp);
+ hc->tx_pipe--;
+ }
+ if (seqp == hc->tx_seqt)
+ break;
+ seqp = seqp->ccid2s_prev;
+ }
+
+ hc->tx_seqt = last_acked;
+ }
+
+ /* trim acked packets in tail */
+ while (hc->tx_seqt != hc->tx_seqh) {
+ if (!hc->tx_seqt->ccid2s_acked)
+ break;
+
+ hc->tx_seqt = hc->tx_seqt->ccid2s_next;
+ }
+
+ /* restart RTO timer if not all outstanding data has been acked */
+ if (hc->tx_pipe == 0)
+ sk_stop_timer(sk, &hc->tx_rtotimer);
+ else
+ sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto);
+done:
+ /* check if incoming Acks allow pending packets to be sent */
+ if (sender_was_blocked && !ccid2_cwnd_network_limited(hc))
+ dccp_tasklet_schedule(sk);
+ dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks);
+}
+
+static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
+{
+ struct ccid2_hc_tx_sock *hc = ccid_priv(ccid);
+ struct dccp_sock *dp = dccp_sk(sk);
+ u32 max_ratio;
+
+ /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */
+ hc->tx_ssthresh = ~0U;
+
+ /* Use larger initial windows (RFC 4341, section 5). */
+ hc->tx_cwnd = rfc3390_bytes_to_packets(dp->dccps_mss_cache);
+ hc->tx_expected_wnd = hc->tx_cwnd;
+
+ /* Make sure that Ack Ratio is enabled and within bounds. */
+ max_ratio = DIV_ROUND_UP(hc->tx_cwnd, 2);
+ if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio)
+ dp->dccps_l_ack_ratio = max_ratio;
+
+ /* XXX init ~ to window size... */
+ if (ccid2_hc_tx_alloc_seq(hc))
+ return -ENOMEM;
+
+ hc->tx_rto = DCCP_TIMEOUT_INIT;
+ hc->tx_rpdupack = -1;
+ hc->tx_last_cong = hc->tx_lsndtime = hc->tx_cwnd_stamp = ccid2_jiffies32;
+ hc->tx_cwnd_used = 0;
+ hc->sk = sk;
+ timer_setup(&hc->tx_rtotimer, ccid2_hc_tx_rto_expire, 0);
+ INIT_LIST_HEAD(&hc->tx_av_chunks);
+ return 0;
+}
+
+static void ccid2_hc_tx_exit(struct sock *sk)
+{
+ struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
+ int i;
+
+ sk_stop_timer(sk, &hc->tx_rtotimer);
+
+ for (i = 0; i < hc->tx_seqbufc; i++)
+ kfree(hc->tx_seqbuf[i]);
+ hc->tx_seqbufc = 0;
+ dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks);
+}
+
+static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
+{
+ struct ccid2_hc_rx_sock *hc = ccid2_hc_rx_sk(sk);
+
+ if (!dccp_data_packet(skb))
+ return;
+
+ if (++hc->rx_num_data_pkts >= dccp_sk(sk)->dccps_r_ack_ratio) {
+ dccp_send_ack(sk);
+ hc->rx_num_data_pkts = 0;
+ }
+}
+
+struct ccid_operations ccid2_ops = {
+ .ccid_id = DCCPC_CCID2,
+ .ccid_name = "TCP-like",
+ .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,
+};
+
+#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
+module_param(ccid2_debug, bool, 0644);
+MODULE_PARM_DESC(ccid2_debug, "Enable CCID-2 debug messages");
+#endif