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![Alexey Kodanev](/assets/img/avatar_default.png)
The shift of 'cwnd' with '(now - hc->tx_lsndtime) / hc->tx_rto' value
can lead to undefined behavior [1].
In order to fix this use a gradual shift of the window with a 'while'
loop, similar to what tcp_cwnd_restart() is doing.
When comparing delta and RTO there is a minor difference between TCP
and DCCP, the last one also invokes dccp_cwnd_restart() and reduces
'cwnd' if delta equals RTO. That case is preserved in this change.
[1]:
[40850.963623] UBSAN: Undefined behaviour in net/dccp/ccids/ccid2.c:237:7
[40851.043858] shift exponent 67 is too large for 32-bit type 'unsigned int'
[40851.127163] CPU: 3 PID: 15940 Comm: netstress Tainted: G W E 4.18.0-rc7.x86_64 #1
...
[40851.377176] Call Trace:
[40851.408503] dump_stack+0xf1/0x17b
[40851.451331] ? show_regs_print_info+0x5/0x5
[40851.503555] ubsan_epilogue+0x9/0x7c
[40851.548363] __ubsan_handle_shift_out_of_bounds+0x25b/0x2b4
[40851.617109] ? __ubsan_handle_load_invalid_value+0x18f/0x18f
[40851.686796] ? xfrm4_output_finish+0x80/0x80
[40851.739827] ? lock_downgrade+0x6d0/0x6d0
[40851.789744] ? xfrm4_prepare_output+0x160/0x160
[40851.845912] ? ip_queue_xmit+0x810/0x1db0
[40851.895845] ? ccid2_hc_tx_packet_sent+0xd36/0x10a0 [dccp]
[40851.963530] ccid2_hc_tx_packet_sent+0xd36/0x10a0 [dccp]
[40852.029063] dccp_xmit_packet+0x1d3/0x720 [dccp]
[40852.086254] dccp_write_xmit+0x116/0x1d0 [dccp]
[40852.142412] dccp_sendmsg+0x428/0xb20 [dccp]
[40852.195454] ? inet_dccp_listen+0x200/0x200 [dccp]
[40852.254833] ? sched_clock+0x5/0x10
[40852.298508] ? sched_clock+0x5/0x10
[40852.342194] ? inet_create+0xdf0/0xdf0
[40852.388988] sock_sendmsg+0xd9/0x160
...
Fixes: 113ced1f52
("dccp ccid-2: Perform congestion-window validation")
Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
801 lines
24 KiB
C
801 lines
24 KiB
C
/*
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* Copyright (c) 2005, 2006 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
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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 <acme@conectiva.com.br>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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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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* 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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* 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;
|
|
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
|