diff options
Diffstat (limited to 'net/dccp/ccids/ccid2.c')
| -rw-r--r-- | net/dccp/ccids/ccid2.c | 793 |
1 files changed, 793 insertions, 0 deletions
diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c new file mode 100644 index 0000000000..4d9823d6dc --- /dev/null +++ b/net/dccp/ccids/ccid2.c @@ -0,0 +1,793 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * 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 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 + * @hc: socket to update window + * @new_wnd: new window values to add into the filter + * + * 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 + * @sk: socket to perform estimator on + * + * 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 |