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793 lines
23 KiB
793 lines
23 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Copyright (c) 2005, 2006 Andrea Bittau <[email protected]> |
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* |
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* Changes to meet Linux coding standards, and DCCP infrastructure fixes. |
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* |
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* Copyright (c) 2006 Arnaldo Carvalho de Melo <[email protected]> |
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*/ |
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|
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/* |
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* This implementation should follow RFC 4341 |
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*/ |
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#include <linux/slab.h> |
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#include "../feat.h" |
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#include "ccid2.h" |
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#ifdef CONFIG_IP_DCCP_CCID2_DEBUG |
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static bool ccid2_debug; |
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#define ccid2_pr_debug(format, a...) DCCP_PR_DEBUG(ccid2_debug, format, ##a) |
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#else |
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#define ccid2_pr_debug(format, a...) |
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#endif |
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static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hc) |
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{ |
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struct ccid2_seq *seqp; |
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int i; |
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/* check if we have space to preserve the pointer to the buffer */ |
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if (hc->tx_seqbufc >= (sizeof(hc->tx_seqbuf) / |
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sizeof(struct ccid2_seq *))) |
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return -ENOMEM; |
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/* allocate buffer and initialize linked list */ |
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seqp = kmalloc_array(CCID2_SEQBUF_LEN, sizeof(struct ccid2_seq), |
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gfp_any()); |
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if (seqp == NULL) |
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return -ENOMEM; |
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for (i = 0; i < (CCID2_SEQBUF_LEN - 1); i++) { |
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seqp[i].ccid2s_next = &seqp[i + 1]; |
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seqp[i + 1].ccid2s_prev = &seqp[i]; |
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} |
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seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = seqp; |
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seqp->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1]; |
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/* This is the first allocation. Initiate the head and tail. */ |
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if (hc->tx_seqbufc == 0) |
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hc->tx_seqh = hc->tx_seqt = seqp; |
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else { |
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/* link the existing list with the one we just created */ |
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hc->tx_seqh->ccid2s_next = seqp; |
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seqp->ccid2s_prev = hc->tx_seqh; |
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hc->tx_seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1]; |
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seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hc->tx_seqt; |
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} |
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/* store the original pointer to the buffer so we can free it */ |
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hc->tx_seqbuf[hc->tx_seqbufc] = seqp; |
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hc->tx_seqbufc++; |
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return 0; |
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} |
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static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) |
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{ |
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if (ccid2_cwnd_network_limited(ccid2_hc_tx_sk(sk))) |
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return CCID_PACKET_WILL_DEQUEUE_LATER; |
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return CCID_PACKET_SEND_AT_ONCE; |
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} |
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static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val) |
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{ |
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u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->tx_cwnd, 2); |
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/* |
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* Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from |
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* RFC 4341, 6.1.2. We ignore the statement that Ack Ratio 2 is always |
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* acceptable since this causes starvation/deadlock whenever cwnd < 2. |
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* The same problem arises when Ack Ratio is 0 (ie. Ack Ratio disabled). |
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*/ |
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if (val == 0 || val > max_ratio) { |
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DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio); |
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val = max_ratio; |
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} |
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dccp_feat_signal_nn_change(sk, DCCPF_ACK_RATIO, |
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min_t(u32, val, DCCPF_ACK_RATIO_MAX)); |
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} |
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static void ccid2_check_l_ack_ratio(struct sock *sk) |
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{ |
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struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
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/* |
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* After a loss, idle period, application limited period, or RTO we |
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* need to check that the ack ratio is still less than the congestion |
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* window. Otherwise, we will send an entire congestion window of |
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* packets and got no response because we haven't sent ack ratio |
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* packets yet. |
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* If the ack ratio does need to be reduced, we reduce it to half of |
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* the congestion window (or 1 if that's zero) instead of to the |
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* congestion window. This prevents problems if one ack is lost. |
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*/ |
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if (dccp_feat_nn_get(sk, DCCPF_ACK_RATIO) > hc->tx_cwnd) |
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ccid2_change_l_ack_ratio(sk, hc->tx_cwnd/2 ? : 1U); |
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} |
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static void ccid2_change_l_seq_window(struct sock *sk, u64 val) |
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{ |
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dccp_feat_signal_nn_change(sk, DCCPF_SEQUENCE_WINDOW, |
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clamp_val(val, DCCPF_SEQ_WMIN, |
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DCCPF_SEQ_WMAX)); |
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} |
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static void dccp_tasklet_schedule(struct sock *sk) |
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{ |
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struct tasklet_struct *t = &dccp_sk(sk)->dccps_xmitlet; |
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if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { |
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sock_hold(sk); |
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__tasklet_schedule(t); |
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} |
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} |
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static void ccid2_hc_tx_rto_expire(struct timer_list *t) |
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{ |
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struct ccid2_hc_tx_sock *hc = from_timer(hc, t, tx_rtotimer); |
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struct sock *sk = hc->sk; |
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const bool sender_was_blocked = ccid2_cwnd_network_limited(hc); |
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bh_lock_sock(sk); |
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if (sock_owned_by_user(sk)) { |
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sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + HZ / 5); |
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goto out; |
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} |
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ccid2_pr_debug("RTO_EXPIRE\n"); |
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if (sk->sk_state == DCCP_CLOSED) |
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goto out; |
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/* back-off timer */ |
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hc->tx_rto <<= 1; |
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if (hc->tx_rto > DCCP_RTO_MAX) |
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hc->tx_rto = DCCP_RTO_MAX; |
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/* adjust pipe, cwnd etc */ |
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hc->tx_ssthresh = hc->tx_cwnd / 2; |
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if (hc->tx_ssthresh < 2) |
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hc->tx_ssthresh = 2; |
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hc->tx_cwnd = 1; |
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hc->tx_pipe = 0; |
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/* clear state about stuff we sent */ |
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hc->tx_seqt = hc->tx_seqh; |
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hc->tx_packets_acked = 0; |
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/* clear ack ratio state. */ |
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hc->tx_rpseq = 0; |
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hc->tx_rpdupack = -1; |
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ccid2_change_l_ack_ratio(sk, 1); |
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/* if we were blocked before, we may now send cwnd=1 packet */ |
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if (sender_was_blocked) |
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dccp_tasklet_schedule(sk); |
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/* restart backed-off timer */ |
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sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); |
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out: |
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bh_unlock_sock(sk); |
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sock_put(sk); |
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} |
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/* |
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* Congestion window validation (RFC 2861). |
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*/ |
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static bool ccid2_do_cwv = true; |
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module_param(ccid2_do_cwv, bool, 0644); |
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MODULE_PARM_DESC(ccid2_do_cwv, "Perform RFC2861 Congestion Window Validation"); |
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/** |
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* ccid2_update_used_window - Track how much of cwnd is actually used |
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* @hc: socket to update window |
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* @new_wnd: new window values to add into the filter |
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* |
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* This is done in addition to CWV. The sender needs to have an idea of how many |
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* packets may be in flight, to set the local Sequence Window value accordingly |
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* (RFC 4340, 7.5.2). The CWV mechanism is exploited to keep track of the |
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* maximum-used window. We use an EWMA low-pass filter to filter out noise. |
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*/ |
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static void ccid2_update_used_window(struct ccid2_hc_tx_sock *hc, u32 new_wnd) |
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{ |
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hc->tx_expected_wnd = (3 * hc->tx_expected_wnd + new_wnd) / 4; |
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} |
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/* This borrows the code of tcp_cwnd_application_limited() */ |
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static void ccid2_cwnd_application_limited(struct sock *sk, const u32 now) |
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{ |
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struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
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/* don't reduce cwnd below the initial window (IW) */ |
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u32 init_win = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache), |
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win_used = max(hc->tx_cwnd_used, init_win); |
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if (win_used < hc->tx_cwnd) { |
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hc->tx_ssthresh = max(hc->tx_ssthresh, |
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(hc->tx_cwnd >> 1) + (hc->tx_cwnd >> 2)); |
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hc->tx_cwnd = (hc->tx_cwnd + win_used) >> 1; |
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} |
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hc->tx_cwnd_used = 0; |
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hc->tx_cwnd_stamp = now; |
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ccid2_check_l_ack_ratio(sk); |
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} |
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/* This borrows the code of tcp_cwnd_restart() */ |
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static void ccid2_cwnd_restart(struct sock *sk, const u32 now) |
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{ |
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struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
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u32 cwnd = hc->tx_cwnd, restart_cwnd, |
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iwnd = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache); |
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s32 delta = now - hc->tx_lsndtime; |
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hc->tx_ssthresh = max(hc->tx_ssthresh, (cwnd >> 1) + (cwnd >> 2)); |
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/* don't reduce cwnd below the initial window (IW) */ |
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restart_cwnd = min(cwnd, iwnd); |
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while ((delta -= hc->tx_rto) >= 0 && cwnd > restart_cwnd) |
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cwnd >>= 1; |
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hc->tx_cwnd = max(cwnd, restart_cwnd); |
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hc->tx_cwnd_stamp = now; |
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hc->tx_cwnd_used = 0; |
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ccid2_check_l_ack_ratio(sk); |
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} |
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static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len) |
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{ |
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struct dccp_sock *dp = dccp_sk(sk); |
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struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
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const u32 now = ccid2_jiffies32; |
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struct ccid2_seq *next; |
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/* slow-start after idle periods (RFC 2581, RFC 2861) */ |
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if (ccid2_do_cwv && !hc->tx_pipe && |
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(s32)(now - hc->tx_lsndtime) >= hc->tx_rto) |
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ccid2_cwnd_restart(sk, now); |
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hc->tx_lsndtime = now; |
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hc->tx_pipe += 1; |
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/* see whether cwnd was fully used (RFC 2861), update expected window */ |
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if (ccid2_cwnd_network_limited(hc)) { |
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ccid2_update_used_window(hc, hc->tx_cwnd); |
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hc->tx_cwnd_used = 0; |
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hc->tx_cwnd_stamp = now; |
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} else { |
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if (hc->tx_pipe > hc->tx_cwnd_used) |
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hc->tx_cwnd_used = hc->tx_pipe; |
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ccid2_update_used_window(hc, hc->tx_cwnd_used); |
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if (ccid2_do_cwv && (s32)(now - hc->tx_cwnd_stamp) >= hc->tx_rto) |
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ccid2_cwnd_application_limited(sk, now); |
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} |
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hc->tx_seqh->ccid2s_seq = dp->dccps_gss; |
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hc->tx_seqh->ccid2s_acked = 0; |
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hc->tx_seqh->ccid2s_sent = now; |
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next = hc->tx_seqh->ccid2s_next; |
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/* check if we need to alloc more space */ |
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if (next == hc->tx_seqt) { |
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if (ccid2_hc_tx_alloc_seq(hc)) { |
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DCCP_CRIT("packet history - out of memory!"); |
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/* FIXME: find a more graceful way to bail out */ |
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return; |
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} |
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next = hc->tx_seqh->ccid2s_next; |
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BUG_ON(next == hc->tx_seqt); |
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} |
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hc->tx_seqh = next; |
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ccid2_pr_debug("cwnd=%d pipe=%d\n", hc->tx_cwnd, hc->tx_pipe); |
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/* |
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* FIXME: The code below is broken and the variables have been removed |
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* from the socket struct. The `ackloss' variable was always set to 0, |
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* and with arsent there are several problems: |
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* (i) it doesn't just count the number of Acks, but all sent packets; |
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* (ii) it is expressed in # of packets, not # of windows, so the |
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* comparison below uses the wrong formula: Appendix A of RFC 4341 |
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* comes up with the number K = cwnd / (R^2 - R) of consecutive windows |
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* of data with no lost or marked Ack packets. If arsent were the # of |
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* consecutive Acks received without loss, then Ack Ratio needs to be |
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* decreased by 1 when |
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* arsent >= K * cwnd / R = cwnd^2 / (R^3 - R^2) |
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* where cwnd / R is the number of Acks received per window of data |
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* (cf. RFC 4341, App. A). The problems are that |
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* - arsent counts other packets as well; |
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* - the comparison uses a formula different from RFC 4341; |
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* - computing a cubic/quadratic equation each time is too complicated. |
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* Hence a different algorithm is needed. |
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*/ |
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#if 0 |
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/* Ack Ratio. Need to maintain a concept of how many windows we sent */ |
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hc->tx_arsent++; |
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/* We had an ack loss in this window... */ |
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if (hc->tx_ackloss) { |
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if (hc->tx_arsent >= hc->tx_cwnd) { |
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hc->tx_arsent = 0; |
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hc->tx_ackloss = 0; |
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} |
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} else { |
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/* No acks lost up to now... */ |
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/* decrease ack ratio if enough packets were sent */ |
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if (dp->dccps_l_ack_ratio > 1) { |
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/* XXX don't calculate denominator each time */ |
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int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio - |
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dp->dccps_l_ack_ratio; |
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denom = hc->tx_cwnd * hc->tx_cwnd / denom; |
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if (hc->tx_arsent >= denom) { |
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ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1); |
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hc->tx_arsent = 0; |
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} |
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} else { |
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/* we can't increase ack ratio further [1] */ |
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hc->tx_arsent = 0; /* or maybe set it to cwnd*/ |
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} |
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} |
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#endif |
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sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); |
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#ifdef CONFIG_IP_DCCP_CCID2_DEBUG |
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do { |
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struct ccid2_seq *seqp = hc->tx_seqt; |
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while (seqp != hc->tx_seqh) { |
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ccid2_pr_debug("out seq=%llu acked=%d time=%u\n", |
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(unsigned long long)seqp->ccid2s_seq, |
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seqp->ccid2s_acked, seqp->ccid2s_sent); |
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seqp = seqp->ccid2s_next; |
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} |
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} while (0); |
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ccid2_pr_debug("=========\n"); |
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#endif |
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} |
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/** |
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* ccid2_rtt_estimator - Sample RTT and compute RTO using RFC2988 algorithm |
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* @sk: socket to perform estimator on |
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* |
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* This code is almost identical with TCP's tcp_rtt_estimator(), since |
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* - it has a higher sampling frequency (recommended by RFC 1323), |
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* - the RTO does not collapse into RTT due to RTTVAR going towards zero, |
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* - it is simple (cf. more complex proposals such as Eifel timer or research |
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* which suggests that the gain should be set according to window size), |
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* - in tests it was found to work well with CCID2 [gerrit]. |
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*/ |
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static void ccid2_rtt_estimator(struct sock *sk, const long mrtt) |
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{ |
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struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
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long m = mrtt ? : 1; |
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if (hc->tx_srtt == 0) { |
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/* First measurement m */ |
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hc->tx_srtt = m << 3; |
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hc->tx_mdev = m << 1; |
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hc->tx_mdev_max = max(hc->tx_mdev, tcp_rto_min(sk)); |
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hc->tx_rttvar = hc->tx_mdev_max; |
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|
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hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss; |
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} else { |
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/* Update scaled SRTT as SRTT += 1/8 * (m - SRTT) */ |
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m -= (hc->tx_srtt >> 3); |
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hc->tx_srtt += m; |
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|
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/* Similarly, update scaled mdev with regard to |m| */ |
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if (m < 0) { |
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m = -m; |
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m -= (hc->tx_mdev >> 2); |
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/* |
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* This neutralises RTO increase when RTT < SRTT - mdev |
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* (see P. Sarolahti, A. Kuznetsov,"Congestion Control |
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* in Linux TCP", USENIX 2002, pp. 49-62). |
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*/ |
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if (m > 0) |
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m >>= 3; |
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} else { |
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m -= (hc->tx_mdev >> 2); |
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} |
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hc->tx_mdev += m; |
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|
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if (hc->tx_mdev > hc->tx_mdev_max) { |
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hc->tx_mdev_max = hc->tx_mdev; |
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if (hc->tx_mdev_max > hc->tx_rttvar) |
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hc->tx_rttvar = hc->tx_mdev_max; |
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} |
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|
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/* |
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* Decay RTTVAR at most once per flight, exploiting that |
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* 1) pipe <= cwnd <= Sequence_Window = W (RFC 4340, 7.5.2) |
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* 2) AWL = GSS-W+1 <= GAR <= GSS (RFC 4340, 7.5.1) |
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* GAR is a useful bound for FlightSize = pipe. |
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* AWL is probably too low here, as it over-estimates pipe. |
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*/ |
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if (after48(dccp_sk(sk)->dccps_gar, hc->tx_rtt_seq)) { |
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if (hc->tx_mdev_max < hc->tx_rttvar) |
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hc->tx_rttvar -= (hc->tx_rttvar - |
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hc->tx_mdev_max) >> 2; |
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hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss; |
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hc->tx_mdev_max = tcp_rto_min(sk); |
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} |
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} |
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|
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/* |
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* Set RTO from SRTT and RTTVAR |
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* As in TCP, 4 * RTTVAR >= TCP_RTO_MIN, giving a minimum RTO of 200 ms. |
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* This agrees with RFC 4341, 5: |
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* "Because DCCP does not retransmit data, DCCP does not require |
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* TCP's recommended minimum timeout of one second". |
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*/ |
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hc->tx_rto = (hc->tx_srtt >> 3) + hc->tx_rttvar; |
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|
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if (hc->tx_rto > DCCP_RTO_MAX) |
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hc->tx_rto = DCCP_RTO_MAX; |
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} |
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|
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static void ccid2_new_ack(struct sock *sk, struct ccid2_seq *seqp, |
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unsigned int *maxincr) |
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{ |
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struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
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struct dccp_sock *dp = dccp_sk(sk); |
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int r_seq_used = hc->tx_cwnd / dp->dccps_l_ack_ratio; |
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|
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if (hc->tx_cwnd < dp->dccps_l_seq_win && |
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r_seq_used < dp->dccps_r_seq_win) { |
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if (hc->tx_cwnd < hc->tx_ssthresh) { |
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if (*maxincr > 0 && ++hc->tx_packets_acked >= 2) { |
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hc->tx_cwnd += 1; |
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*maxincr -= 1; |
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hc->tx_packets_acked = 0; |
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} |
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} else if (++hc->tx_packets_acked >= hc->tx_cwnd) { |
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hc->tx_cwnd += 1; |
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hc->tx_packets_acked = 0; |
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} |
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} |
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|
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/* |
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* Adjust the local sequence window and the ack ratio to allow about |
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* 5 times the number of packets in the network (RFC 4340 7.5.2) |
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*/ |
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if (r_seq_used * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_r_seq_win) |
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ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio * 2); |
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else if (r_seq_used * CCID2_WIN_CHANGE_FACTOR < dp->dccps_r_seq_win/2) |
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ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio / 2 ? : 1U); |
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|
|
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
|
|
|