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![Wei Wang](/assets/img/avatar_default.png)
Add gfp_t mask as an input parameter to mem_cgroup_charge_skmem(), to give more control to the networking stack and enable it to change memcg charging behavior. In the future, the networking stack may decide to avoid oom-kills when fallbacks are more appropriate. One behavior change in mem_cgroup_charge_skmem() by this patch is to avoid force charging by default and let the caller decide when and if force charging is needed through the presence or absence of __GFP_NOFAIL. Signed-off-by: Wei Wang <weiwan@google.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
4123 lines
119 KiB
C
4123 lines
119 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* INET An implementation of the TCP/IP protocol suite for the LINUX
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* operating system. INET is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* Implementation of the Transmission Control Protocol(TCP).
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*
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* Authors: Ross Biro
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* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
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* Mark Evans, <evansmp@uhura.aston.ac.uk>
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* Corey Minyard <wf-rch!minyard@relay.EU.net>
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* Florian La Roche, <flla@stud.uni-sb.de>
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* Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
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* Linus Torvalds, <torvalds@cs.helsinki.fi>
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* Alan Cox, <gw4pts@gw4pts.ampr.org>
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* Matthew Dillon, <dillon@apollo.west.oic.com>
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* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
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* Jorge Cwik, <jorge@laser.satlink.net>
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*/
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/*
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* Changes: Pedro Roque : Retransmit queue handled by TCP.
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* : Fragmentation on mtu decrease
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* : Segment collapse on retransmit
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* : AF independence
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*
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* Linus Torvalds : send_delayed_ack
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* David S. Miller : Charge memory using the right skb
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* during syn/ack processing.
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* David S. Miller : Output engine completely rewritten.
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* Andrea Arcangeli: SYNACK carry ts_recent in tsecr.
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* Cacophonix Gaul : draft-minshall-nagle-01
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* J Hadi Salim : ECN support
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*
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*/
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#define pr_fmt(fmt) "TCP: " fmt
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#include <net/tcp.h>
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#include <net/mptcp.h>
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#include <linux/compiler.h>
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#include <linux/gfp.h>
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#include <linux/module.h>
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#include <linux/static_key.h>
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#include <trace/events/tcp.h>
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/* Refresh clocks of a TCP socket,
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* ensuring monotically increasing values.
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*/
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void tcp_mstamp_refresh(struct tcp_sock *tp)
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{
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u64 val = tcp_clock_ns();
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tp->tcp_clock_cache = val;
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tp->tcp_mstamp = div_u64(val, NSEC_PER_USEC);
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}
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static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
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int push_one, gfp_t gfp);
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/* Account for new data that has been sent to the network. */
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static void tcp_event_new_data_sent(struct sock *sk, struct sk_buff *skb)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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struct tcp_sock *tp = tcp_sk(sk);
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unsigned int prior_packets = tp->packets_out;
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WRITE_ONCE(tp->snd_nxt, TCP_SKB_CB(skb)->end_seq);
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__skb_unlink(skb, &sk->sk_write_queue);
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tcp_rbtree_insert(&sk->tcp_rtx_queue, skb);
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if (tp->highest_sack == NULL)
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tp->highest_sack = skb;
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tp->packets_out += tcp_skb_pcount(skb);
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if (!prior_packets || icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)
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tcp_rearm_rto(sk);
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NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT,
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tcp_skb_pcount(skb));
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}
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/* SND.NXT, if window was not shrunk or the amount of shrunk was less than one
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* window scaling factor due to loss of precision.
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* If window has been shrunk, what should we make? It is not clear at all.
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* Using SND.UNA we will fail to open window, SND.NXT is out of window. :-(
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* Anything in between SND.UNA...SND.UNA+SND.WND also can be already
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* invalid. OK, let's make this for now:
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*/
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static inline __u32 tcp_acceptable_seq(const struct sock *sk)
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{
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const struct tcp_sock *tp = tcp_sk(sk);
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if (!before(tcp_wnd_end(tp), tp->snd_nxt) ||
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(tp->rx_opt.wscale_ok &&
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((tp->snd_nxt - tcp_wnd_end(tp)) < (1 << tp->rx_opt.rcv_wscale))))
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return tp->snd_nxt;
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else
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return tcp_wnd_end(tp);
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}
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/* Calculate mss to advertise in SYN segment.
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* RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that:
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*
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* 1. It is independent of path mtu.
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* 2. Ideally, it is maximal possible segment size i.e. 65535-40.
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* 3. For IPv4 it is reasonable to calculate it from maximal MTU of
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* attached devices, because some buggy hosts are confused by
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* large MSS.
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* 4. We do not make 3, we advertise MSS, calculated from first
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* hop device mtu, but allow to raise it to ip_rt_min_advmss.
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* This may be overridden via information stored in routing table.
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* 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible,
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* probably even Jumbo".
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*/
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static __u16 tcp_advertise_mss(struct sock *sk)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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const struct dst_entry *dst = __sk_dst_get(sk);
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int mss = tp->advmss;
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if (dst) {
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unsigned int metric = dst_metric_advmss(dst);
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if (metric < mss) {
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mss = metric;
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tp->advmss = mss;
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}
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}
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return (__u16)mss;
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}
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/* RFC2861. Reset CWND after idle period longer RTO to "restart window".
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* This is the first part of cwnd validation mechanism.
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*/
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void tcp_cwnd_restart(struct sock *sk, s32 delta)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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u32 restart_cwnd = tcp_init_cwnd(tp, __sk_dst_get(sk));
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u32 cwnd = tp->snd_cwnd;
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tcp_ca_event(sk, CA_EVENT_CWND_RESTART);
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tp->snd_ssthresh = tcp_current_ssthresh(sk);
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restart_cwnd = min(restart_cwnd, cwnd);
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while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd)
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cwnd >>= 1;
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tp->snd_cwnd = max(cwnd, restart_cwnd);
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tp->snd_cwnd_stamp = tcp_jiffies32;
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tp->snd_cwnd_used = 0;
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}
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/* Congestion state accounting after a packet has been sent. */
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static void tcp_event_data_sent(struct tcp_sock *tp,
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struct sock *sk)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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const u32 now = tcp_jiffies32;
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if (tcp_packets_in_flight(tp) == 0)
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tcp_ca_event(sk, CA_EVENT_TX_START);
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/* If this is the first data packet sent in response to the
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* previous received data,
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* and it is a reply for ato after last received packet,
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* increase pingpong count.
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*/
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if (before(tp->lsndtime, icsk->icsk_ack.lrcvtime) &&
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(u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato)
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inet_csk_inc_pingpong_cnt(sk);
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tp->lsndtime = now;
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}
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/* Account for an ACK we sent. */
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static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts,
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u32 rcv_nxt)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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if (unlikely(tp->compressed_ack)) {
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NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPACKCOMPRESSED,
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tp->compressed_ack);
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tp->compressed_ack = 0;
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if (hrtimer_try_to_cancel(&tp->compressed_ack_timer) == 1)
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__sock_put(sk);
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}
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if (unlikely(rcv_nxt != tp->rcv_nxt))
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return; /* Special ACK sent by DCTCP to reflect ECN */
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tcp_dec_quickack_mode(sk, pkts);
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inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
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}
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/* Determine a window scaling and initial window to offer.
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* Based on the assumption that the given amount of space
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* will be offered. Store the results in the tp structure.
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* NOTE: for smooth operation initial space offering should
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* be a multiple of mss if possible. We assume here that mss >= 1.
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* This MUST be enforced by all callers.
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*/
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void tcp_select_initial_window(const struct sock *sk, int __space, __u32 mss,
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__u32 *rcv_wnd, __u32 *window_clamp,
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int wscale_ok, __u8 *rcv_wscale,
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__u32 init_rcv_wnd)
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{
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unsigned int space = (__space < 0 ? 0 : __space);
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/* If no clamp set the clamp to the max possible scaled window */
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if (*window_clamp == 0)
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(*window_clamp) = (U16_MAX << TCP_MAX_WSCALE);
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space = min(*window_clamp, space);
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/* Quantize space offering to a multiple of mss if possible. */
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if (space > mss)
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space = rounddown(space, mss);
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/* NOTE: offering an initial window larger than 32767
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* will break some buggy TCP stacks. If the admin tells us
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* it is likely we could be speaking with such a buggy stack
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* we will truncate our initial window offering to 32K-1
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* unless the remote has sent us a window scaling option,
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* which we interpret as a sign the remote TCP is not
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* misinterpreting the window field as a signed quantity.
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*/
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if (sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows)
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(*rcv_wnd) = min(space, MAX_TCP_WINDOW);
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else
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(*rcv_wnd) = min_t(u32, space, U16_MAX);
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if (init_rcv_wnd)
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*rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss);
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*rcv_wscale = 0;
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if (wscale_ok) {
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/* Set window scaling on max possible window */
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space = max_t(u32, space, sock_net(sk)->ipv4.sysctl_tcp_rmem[2]);
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space = max_t(u32, space, sysctl_rmem_max);
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space = min_t(u32, space, *window_clamp);
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*rcv_wscale = clamp_t(int, ilog2(space) - 15,
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0, TCP_MAX_WSCALE);
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}
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/* Set the clamp no higher than max representable value */
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(*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp);
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}
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EXPORT_SYMBOL(tcp_select_initial_window);
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/* Chose a new window to advertise, update state in tcp_sock for the
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* socket, and return result with RFC1323 scaling applied. The return
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* value can be stuffed directly into th->window for an outgoing
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* frame.
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*/
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static u16 tcp_select_window(struct sock *sk)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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u32 old_win = tp->rcv_wnd;
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u32 cur_win = tcp_receive_window(tp);
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u32 new_win = __tcp_select_window(sk);
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/* Never shrink the offered window */
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if (new_win < cur_win) {
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/* Danger Will Robinson!
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* Don't update rcv_wup/rcv_wnd here or else
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* we will not be able to advertise a zero
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* window in time. --DaveM
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*
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* Relax Will Robinson.
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*/
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if (new_win == 0)
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NET_INC_STATS(sock_net(sk),
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LINUX_MIB_TCPWANTZEROWINDOWADV);
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new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale);
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}
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tp->rcv_wnd = new_win;
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tp->rcv_wup = tp->rcv_nxt;
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/* Make sure we do not exceed the maximum possible
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* scaled window.
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*/
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if (!tp->rx_opt.rcv_wscale &&
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sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows)
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new_win = min(new_win, MAX_TCP_WINDOW);
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else
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new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale));
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/* RFC1323 scaling applied */
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new_win >>= tp->rx_opt.rcv_wscale;
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/* If we advertise zero window, disable fast path. */
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if (new_win == 0) {
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tp->pred_flags = 0;
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if (old_win)
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NET_INC_STATS(sock_net(sk),
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LINUX_MIB_TCPTOZEROWINDOWADV);
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} else if (old_win == 0) {
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NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFROMZEROWINDOWADV);
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}
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return new_win;
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}
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/* Packet ECN state for a SYN-ACK */
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static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb)
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{
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const struct tcp_sock *tp = tcp_sk(sk);
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TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR;
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if (!(tp->ecn_flags & TCP_ECN_OK))
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TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE;
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else if (tcp_ca_needs_ecn(sk) ||
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tcp_bpf_ca_needs_ecn(sk))
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INET_ECN_xmit(sk);
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}
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/* Packet ECN state for a SYN. */
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static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk);
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bool use_ecn = sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 ||
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tcp_ca_needs_ecn(sk) || bpf_needs_ecn;
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if (!use_ecn) {
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const struct dst_entry *dst = __sk_dst_get(sk);
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if (dst && dst_feature(dst, RTAX_FEATURE_ECN))
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use_ecn = true;
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}
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tp->ecn_flags = 0;
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if (use_ecn) {
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TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR;
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tp->ecn_flags = TCP_ECN_OK;
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if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn)
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INET_ECN_xmit(sk);
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}
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}
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static void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb)
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{
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if (sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback)
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/* tp->ecn_flags are cleared at a later point in time when
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* SYN ACK is ultimatively being received.
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*/
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TCP_SKB_CB(skb)->tcp_flags &= ~(TCPHDR_ECE | TCPHDR_CWR);
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}
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static void
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tcp_ecn_make_synack(const struct request_sock *req, struct tcphdr *th)
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{
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if (inet_rsk(req)->ecn_ok)
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th->ece = 1;
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}
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/* Set up ECN state for a packet on a ESTABLISHED socket that is about to
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* be sent.
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*/
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static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb,
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struct tcphdr *th, int tcp_header_len)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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if (tp->ecn_flags & TCP_ECN_OK) {
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/* Not-retransmitted data segment: set ECT and inject CWR. */
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if (skb->len != tcp_header_len &&
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!before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) {
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INET_ECN_xmit(sk);
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if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) {
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tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR;
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th->cwr = 1;
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skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
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}
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} else if (!tcp_ca_needs_ecn(sk)) {
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/* ACK or retransmitted segment: clear ECT|CE */
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INET_ECN_dontxmit(sk);
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}
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if (tp->ecn_flags & TCP_ECN_DEMAND_CWR)
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th->ece = 1;
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}
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}
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/* Constructs common control bits of non-data skb. If SYN/FIN is present,
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* auto increment end seqno.
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*/
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static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags)
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{
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skb->ip_summed = CHECKSUM_PARTIAL;
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TCP_SKB_CB(skb)->tcp_flags = flags;
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TCP_SKB_CB(skb)->sacked = 0;
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tcp_skb_pcount_set(skb, 1);
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TCP_SKB_CB(skb)->seq = seq;
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if (flags & (TCPHDR_SYN | TCPHDR_FIN))
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seq++;
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TCP_SKB_CB(skb)->end_seq = seq;
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}
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static inline bool tcp_urg_mode(const struct tcp_sock *tp)
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{
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return tp->snd_una != tp->snd_up;
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}
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|
|
|
#define OPTION_SACK_ADVERTISE (1 << 0)
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#define OPTION_TS (1 << 1)
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#define OPTION_MD5 (1 << 2)
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#define OPTION_WSCALE (1 << 3)
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#define OPTION_FAST_OPEN_COOKIE (1 << 8)
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#define OPTION_SMC (1 << 9)
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#define OPTION_MPTCP (1 << 10)
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static void smc_options_write(__be32 *ptr, u16 *options)
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|
{
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#if IS_ENABLED(CONFIG_SMC)
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if (static_branch_unlikely(&tcp_have_smc)) {
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if (unlikely(OPTION_SMC & *options)) {
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*ptr++ = htonl((TCPOPT_NOP << 24) |
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(TCPOPT_NOP << 16) |
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(TCPOPT_EXP << 8) |
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(TCPOLEN_EXP_SMC_BASE));
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*ptr++ = htonl(TCPOPT_SMC_MAGIC);
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}
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}
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#endif
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}
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|
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struct tcp_out_options {
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u16 options; /* bit field of OPTION_* */
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|
u16 mss; /* 0 to disable */
|
|
u8 ws; /* window scale, 0 to disable */
|
|
u8 num_sack_blocks; /* number of SACK blocks to include */
|
|
u8 hash_size; /* bytes in hash_location */
|
|
u8 bpf_opt_len; /* length of BPF hdr option */
|
|
__u8 *hash_location; /* temporary pointer, overloaded */
|
|
__u32 tsval, tsecr; /* need to include OPTION_TS */
|
|
struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */
|
|
struct mptcp_out_options mptcp;
|
|
};
|
|
|
|
static void mptcp_options_write(__be32 *ptr, const struct tcp_sock *tp,
|
|
struct tcp_out_options *opts)
|
|
{
|
|
#if IS_ENABLED(CONFIG_MPTCP)
|
|
if (unlikely(OPTION_MPTCP & opts->options))
|
|
mptcp_write_options(ptr, tp, &opts->mptcp);
|
|
#endif
|
|
}
|
|
|
|
#ifdef CONFIG_CGROUP_BPF
|
|
static int bpf_skops_write_hdr_opt_arg0(struct sk_buff *skb,
|
|
enum tcp_synack_type synack_type)
|
|
{
|
|
if (unlikely(!skb))
|
|
return BPF_WRITE_HDR_TCP_CURRENT_MSS;
|
|
|
|
if (unlikely(synack_type == TCP_SYNACK_COOKIE))
|
|
return BPF_WRITE_HDR_TCP_SYNACK_COOKIE;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* req, syn_skb and synack_type are used when writing synack */
|
|
static void bpf_skops_hdr_opt_len(struct sock *sk, struct sk_buff *skb,
|
|
struct request_sock *req,
|
|
struct sk_buff *syn_skb,
|
|
enum tcp_synack_type synack_type,
|
|
struct tcp_out_options *opts,
|
|
unsigned int *remaining)
|
|
{
|
|
struct bpf_sock_ops_kern sock_ops;
|
|
int err;
|
|
|
|
if (likely(!BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk),
|
|
BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG)) ||
|
|
!*remaining)
|
|
return;
|
|
|
|
/* *remaining has already been aligned to 4 bytes, so *remaining >= 4 */
|
|
|
|
/* init sock_ops */
|
|
memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
|
|
|
|
sock_ops.op = BPF_SOCK_OPS_HDR_OPT_LEN_CB;
|
|
|
|
if (req) {
|
|
/* The listen "sk" cannot be passed here because
|
|
* it is not locked. It would not make too much
|
|
* sense to do bpf_setsockopt(listen_sk) based
|
|
* on individual connection request also.
|
|
*
|
|
* Thus, "req" is passed here and the cgroup-bpf-progs
|
|
* of the listen "sk" will be run.
|
|
*
|
|
* "req" is also used here for fastopen even the "sk" here is
|
|
* a fullsock "child" sk. It is to keep the behavior
|
|
* consistent between fastopen and non-fastopen on
|
|
* the bpf programming side.
|
|
*/
|
|
sock_ops.sk = (struct sock *)req;
|
|
sock_ops.syn_skb = syn_skb;
|
|
} else {
|
|
sock_owned_by_me(sk);
|
|
|
|
sock_ops.is_fullsock = 1;
|
|
sock_ops.sk = sk;
|
|
}
|
|
|
|
sock_ops.args[0] = bpf_skops_write_hdr_opt_arg0(skb, synack_type);
|
|
sock_ops.remaining_opt_len = *remaining;
|
|
/* tcp_current_mss() does not pass a skb */
|
|
if (skb)
|
|
bpf_skops_init_skb(&sock_ops, skb, 0);
|
|
|
|
err = BPF_CGROUP_RUN_PROG_SOCK_OPS_SK(&sock_ops, sk);
|
|
|
|
if (err || sock_ops.remaining_opt_len == *remaining)
|
|
return;
|
|
|
|
opts->bpf_opt_len = *remaining - sock_ops.remaining_opt_len;
|
|
/* round up to 4 bytes */
|
|
opts->bpf_opt_len = (opts->bpf_opt_len + 3) & ~3;
|
|
|
|
*remaining -= opts->bpf_opt_len;
|
|
}
|
|
|
|
static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb,
|
|
struct request_sock *req,
|
|
struct sk_buff *syn_skb,
|
|
enum tcp_synack_type synack_type,
|
|
struct tcp_out_options *opts)
|
|
{
|
|
u8 first_opt_off, nr_written, max_opt_len = opts->bpf_opt_len;
|
|
struct bpf_sock_ops_kern sock_ops;
|
|
int err;
|
|
|
|
if (likely(!max_opt_len))
|
|
return;
|
|
|
|
memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
|
|
|
|
sock_ops.op = BPF_SOCK_OPS_WRITE_HDR_OPT_CB;
|
|
|
|
if (req) {
|
|
sock_ops.sk = (struct sock *)req;
|
|
sock_ops.syn_skb = syn_skb;
|
|
} else {
|
|
sock_owned_by_me(sk);
|
|
|
|
sock_ops.is_fullsock = 1;
|
|
sock_ops.sk = sk;
|
|
}
|
|
|
|
sock_ops.args[0] = bpf_skops_write_hdr_opt_arg0(skb, synack_type);
|
|
sock_ops.remaining_opt_len = max_opt_len;
|
|
first_opt_off = tcp_hdrlen(skb) - max_opt_len;
|
|
bpf_skops_init_skb(&sock_ops, skb, first_opt_off);
|
|
|
|
err = BPF_CGROUP_RUN_PROG_SOCK_OPS_SK(&sock_ops, sk);
|
|
|
|
if (err)
|
|
nr_written = 0;
|
|
else
|
|
nr_written = max_opt_len - sock_ops.remaining_opt_len;
|
|
|
|
if (nr_written < max_opt_len)
|
|
memset(skb->data + first_opt_off + nr_written, TCPOPT_NOP,
|
|
max_opt_len - nr_written);
|
|
}
|
|
#else
|
|
static void bpf_skops_hdr_opt_len(struct sock *sk, struct sk_buff *skb,
|
|
struct request_sock *req,
|
|
struct sk_buff *syn_skb,
|
|
enum tcp_synack_type synack_type,
|
|
struct tcp_out_options *opts,
|
|
unsigned int *remaining)
|
|
{
|
|
}
|
|
|
|
static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb,
|
|
struct request_sock *req,
|
|
struct sk_buff *syn_skb,
|
|
enum tcp_synack_type synack_type,
|
|
struct tcp_out_options *opts)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
/* Write previously computed TCP options to the packet.
|
|
*
|
|
* Beware: Something in the Internet is very sensitive to the ordering of
|
|
* TCP options, we learned this through the hard way, so be careful here.
|
|
* Luckily we can at least blame others for their non-compliance but from
|
|
* inter-operability perspective it seems that we're somewhat stuck with
|
|
* the ordering which we have been using if we want to keep working with
|
|
* those broken things (not that it currently hurts anybody as there isn't
|
|
* particular reason why the ordering would need to be changed).
|
|
*
|
|
* At least SACK_PERM as the first option is known to lead to a disaster
|
|
* (but it may well be that other scenarios fail similarly).
|
|
*/
|
|
static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
|
|
struct tcp_out_options *opts)
|
|
{
|
|
u16 options = opts->options; /* mungable copy */
|
|
|
|
if (unlikely(OPTION_MD5 & options)) {
|
|
*ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
|
|
(TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG);
|
|
/* overload cookie hash location */
|
|
opts->hash_location = (__u8 *)ptr;
|
|
ptr += 4;
|
|
}
|
|
|
|
if (unlikely(opts->mss)) {
|
|
*ptr++ = htonl((TCPOPT_MSS << 24) |
|
|
(TCPOLEN_MSS << 16) |
|
|
opts->mss);
|
|
}
|
|
|
|
if (likely(OPTION_TS & options)) {
|
|
if (unlikely(OPTION_SACK_ADVERTISE & options)) {
|
|
*ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
|
|
(TCPOLEN_SACK_PERM << 16) |
|
|
(TCPOPT_TIMESTAMP << 8) |
|
|
TCPOLEN_TIMESTAMP);
|
|
options &= ~OPTION_SACK_ADVERTISE;
|
|
} else {
|
|
*ptr++ = htonl((TCPOPT_NOP << 24) |
|
|
(TCPOPT_NOP << 16) |
|
|
(TCPOPT_TIMESTAMP << 8) |
|
|
TCPOLEN_TIMESTAMP);
|
|
}
|
|
*ptr++ = htonl(opts->tsval);
|
|
*ptr++ = htonl(opts->tsecr);
|
|
}
|
|
|
|
if (unlikely(OPTION_SACK_ADVERTISE & options)) {
|
|
*ptr++ = htonl((TCPOPT_NOP << 24) |
|
|
(TCPOPT_NOP << 16) |
|
|
(TCPOPT_SACK_PERM << 8) |
|
|
TCPOLEN_SACK_PERM);
|
|
}
|
|
|
|
if (unlikely(OPTION_WSCALE & options)) {
|
|
*ptr++ = htonl((TCPOPT_NOP << 24) |
|
|
(TCPOPT_WINDOW << 16) |
|
|
(TCPOLEN_WINDOW << 8) |
|
|
opts->ws);
|
|
}
|
|
|
|
if (unlikely(opts->num_sack_blocks)) {
|
|
struct tcp_sack_block *sp = tp->rx_opt.dsack ?
|
|
tp->duplicate_sack : tp->selective_acks;
|
|
int this_sack;
|
|
|
|
*ptr++ = htonl((TCPOPT_NOP << 24) |
|
|
(TCPOPT_NOP << 16) |
|
|
(TCPOPT_SACK << 8) |
|
|
(TCPOLEN_SACK_BASE + (opts->num_sack_blocks *
|
|
TCPOLEN_SACK_PERBLOCK)));
|
|
|
|
for (this_sack = 0; this_sack < opts->num_sack_blocks;
|
|
++this_sack) {
|
|
*ptr++ = htonl(sp[this_sack].start_seq);
|
|
*ptr++ = htonl(sp[this_sack].end_seq);
|
|
}
|
|
|
|
tp->rx_opt.dsack = 0;
|
|
}
|
|
|
|
if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) {
|
|
struct tcp_fastopen_cookie *foc = opts->fastopen_cookie;
|
|
u8 *p = (u8 *)ptr;
|
|
u32 len; /* Fast Open option length */
|
|
|
|
if (foc->exp) {
|
|
len = TCPOLEN_EXP_FASTOPEN_BASE + foc->len;
|
|
*ptr = htonl((TCPOPT_EXP << 24) | (len << 16) |
|
|
TCPOPT_FASTOPEN_MAGIC);
|
|
p += TCPOLEN_EXP_FASTOPEN_BASE;
|
|
} else {
|
|
len = TCPOLEN_FASTOPEN_BASE + foc->len;
|
|
*p++ = TCPOPT_FASTOPEN;
|
|
*p++ = len;
|
|
}
|
|
|
|
memcpy(p, foc->val, foc->len);
|
|
if ((len & 3) == 2) {
|
|
p[foc->len] = TCPOPT_NOP;
|
|
p[foc->len + 1] = TCPOPT_NOP;
|
|
}
|
|
ptr += (len + 3) >> 2;
|
|
}
|
|
|
|
smc_options_write(ptr, &options);
|
|
|
|
mptcp_options_write(ptr, tp, opts);
|
|
}
|
|
|
|
static void smc_set_option(const struct tcp_sock *tp,
|
|
struct tcp_out_options *opts,
|
|
unsigned int *remaining)
|
|
{
|
|
#if IS_ENABLED(CONFIG_SMC)
|
|
if (static_branch_unlikely(&tcp_have_smc)) {
|
|
if (tp->syn_smc) {
|
|
if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) {
|
|
opts->options |= OPTION_SMC;
|
|
*remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED;
|
|
}
|
|
}
|
|
}
|
|
#endif
|
|
}
|
|
|
|
static void smc_set_option_cond(const struct tcp_sock *tp,
|
|
const struct inet_request_sock *ireq,
|
|
struct tcp_out_options *opts,
|
|
unsigned int *remaining)
|
|
{
|
|
#if IS_ENABLED(CONFIG_SMC)
|
|
if (static_branch_unlikely(&tcp_have_smc)) {
|
|
if (tp->syn_smc && ireq->smc_ok) {
|
|
if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) {
|
|
opts->options |= OPTION_SMC;
|
|
*remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED;
|
|
}
|
|
}
|
|
}
|
|
#endif
|
|
}
|
|
|
|
static void mptcp_set_option_cond(const struct request_sock *req,
|
|
struct tcp_out_options *opts,
|
|
unsigned int *remaining)
|
|
{
|
|
if (rsk_is_mptcp(req)) {
|
|
unsigned int size;
|
|
|
|
if (mptcp_synack_options(req, &size, &opts->mptcp)) {
|
|
if (*remaining >= size) {
|
|
opts->options |= OPTION_MPTCP;
|
|
*remaining -= size;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Compute TCP options for SYN packets. This is not the final
|
|
* network wire format yet.
|
|
*/
|
|
static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
|
|
struct tcp_out_options *opts,
|
|
struct tcp_md5sig_key **md5)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
unsigned int remaining = MAX_TCP_OPTION_SPACE;
|
|
struct tcp_fastopen_request *fastopen = tp->fastopen_req;
|
|
|
|
*md5 = NULL;
|
|
#ifdef CONFIG_TCP_MD5SIG
|
|
if (static_branch_unlikely(&tcp_md5_needed) &&
|
|
rcu_access_pointer(tp->md5sig_info)) {
|
|
*md5 = tp->af_specific->md5_lookup(sk, sk);
|
|
if (*md5) {
|
|
opts->options |= OPTION_MD5;
|
|
remaining -= TCPOLEN_MD5SIG_ALIGNED;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/* We always get an MSS option. The option bytes which will be seen in
|
|
* normal data packets should timestamps be used, must be in the MSS
|
|
* advertised. But we subtract them from tp->mss_cache so that
|
|
* calculations in tcp_sendmsg are simpler etc. So account for this
|
|
* fact here if necessary. If we don't do this correctly, as a
|
|
* receiver we won't recognize data packets as being full sized when we
|
|
* should, and thus we won't abide by the delayed ACK rules correctly.
|
|
* SACKs don't matter, we never delay an ACK when we have any of those
|
|
* going out. */
|
|
opts->mss = tcp_advertise_mss(sk);
|
|
remaining -= TCPOLEN_MSS_ALIGNED;
|
|
|
|
if (likely(sock_net(sk)->ipv4.sysctl_tcp_timestamps && !*md5)) {
|
|
opts->options |= OPTION_TS;
|
|
opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset;
|
|
opts->tsecr = tp->rx_opt.ts_recent;
|
|
remaining -= TCPOLEN_TSTAMP_ALIGNED;
|
|
}
|
|
if (likely(sock_net(sk)->ipv4.sysctl_tcp_window_scaling)) {
|
|
opts->ws = tp->rx_opt.rcv_wscale;
|
|
opts->options |= OPTION_WSCALE;
|
|
remaining -= TCPOLEN_WSCALE_ALIGNED;
|
|
}
|
|
if (likely(sock_net(sk)->ipv4.sysctl_tcp_sack)) {
|
|
opts->options |= OPTION_SACK_ADVERTISE;
|
|
if (unlikely(!(OPTION_TS & opts->options)))
|
|
remaining -= TCPOLEN_SACKPERM_ALIGNED;
|
|
}
|
|
|
|
if (fastopen && fastopen->cookie.len >= 0) {
|
|
u32 need = fastopen->cookie.len;
|
|
|
|
need += fastopen->cookie.exp ? TCPOLEN_EXP_FASTOPEN_BASE :
|
|
TCPOLEN_FASTOPEN_BASE;
|
|
need = (need + 3) & ~3U; /* Align to 32 bits */
|
|
if (remaining >= need) {
|
|
opts->options |= OPTION_FAST_OPEN_COOKIE;
|
|
opts->fastopen_cookie = &fastopen->cookie;
|
|
remaining -= need;
|
|
tp->syn_fastopen = 1;
|
|
tp->syn_fastopen_exp = fastopen->cookie.exp ? 1 : 0;
|
|
}
|
|
}
|
|
|
|
smc_set_option(tp, opts, &remaining);
|
|
|
|
if (sk_is_mptcp(sk)) {
|
|
unsigned int size;
|
|
|
|
if (mptcp_syn_options(sk, skb, &size, &opts->mptcp)) {
|
|
opts->options |= OPTION_MPTCP;
|
|
remaining -= size;
|
|
}
|
|
}
|
|
|
|
bpf_skops_hdr_opt_len(sk, skb, NULL, NULL, 0, opts, &remaining);
|
|
|
|
return MAX_TCP_OPTION_SPACE - remaining;
|
|
}
|
|
|
|
/* Set up TCP options for SYN-ACKs. */
|
|
static unsigned int tcp_synack_options(const struct sock *sk,
|
|
struct request_sock *req,
|
|
unsigned int mss, struct sk_buff *skb,
|
|
struct tcp_out_options *opts,
|
|
const struct tcp_md5sig_key *md5,
|
|
struct tcp_fastopen_cookie *foc,
|
|
enum tcp_synack_type synack_type,
|
|
struct sk_buff *syn_skb)
|
|
{
|
|
struct inet_request_sock *ireq = inet_rsk(req);
|
|
unsigned int remaining = MAX_TCP_OPTION_SPACE;
|
|
|
|
#ifdef CONFIG_TCP_MD5SIG
|
|
if (md5) {
|
|
opts->options |= OPTION_MD5;
|
|
remaining -= TCPOLEN_MD5SIG_ALIGNED;
|
|
|
|
/* We can't fit any SACK blocks in a packet with MD5 + TS
|
|
* options. There was discussion about disabling SACK
|
|
* rather than TS in order to fit in better with old,
|
|
* buggy kernels, but that was deemed to be unnecessary.
|
|
*/
|
|
if (synack_type != TCP_SYNACK_COOKIE)
|
|
ireq->tstamp_ok &= !ireq->sack_ok;
|
|
}
|
|
#endif
|
|
|
|
/* We always send an MSS option. */
|
|
opts->mss = mss;
|
|
remaining -= TCPOLEN_MSS_ALIGNED;
|
|
|
|
if (likely(ireq->wscale_ok)) {
|
|
opts->ws = ireq->rcv_wscale;
|
|
opts->options |= OPTION_WSCALE;
|
|
remaining -= TCPOLEN_WSCALE_ALIGNED;
|
|
}
|
|
if (likely(ireq->tstamp_ok)) {
|
|
opts->options |= OPTION_TS;
|
|
opts->tsval = tcp_skb_timestamp(skb) + tcp_rsk(req)->ts_off;
|
|
opts->tsecr = req->ts_recent;
|
|
remaining -= TCPOLEN_TSTAMP_ALIGNED;
|
|
}
|
|
if (likely(ireq->sack_ok)) {
|
|
opts->options |= OPTION_SACK_ADVERTISE;
|
|
if (unlikely(!ireq->tstamp_ok))
|
|
remaining -= TCPOLEN_SACKPERM_ALIGNED;
|
|
}
|
|
if (foc != NULL && foc->len >= 0) {
|
|
u32 need = foc->len;
|
|
|
|
need += foc->exp ? TCPOLEN_EXP_FASTOPEN_BASE :
|
|
TCPOLEN_FASTOPEN_BASE;
|
|
need = (need + 3) & ~3U; /* Align to 32 bits */
|
|
if (remaining >= need) {
|
|
opts->options |= OPTION_FAST_OPEN_COOKIE;
|
|
opts->fastopen_cookie = foc;
|
|
remaining -= need;
|
|
}
|
|
}
|
|
|
|
mptcp_set_option_cond(req, opts, &remaining);
|
|
|
|
smc_set_option_cond(tcp_sk(sk), ireq, opts, &remaining);
|
|
|
|
bpf_skops_hdr_opt_len((struct sock *)sk, skb, req, syn_skb,
|
|
synack_type, opts, &remaining);
|
|
|
|
return MAX_TCP_OPTION_SPACE - remaining;
|
|
}
|
|
|
|
/* Compute TCP options for ESTABLISHED sockets. This is not the
|
|
* final wire format yet.
|
|
*/
|
|
static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb,
|
|
struct tcp_out_options *opts,
|
|
struct tcp_md5sig_key **md5)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
unsigned int size = 0;
|
|
unsigned int eff_sacks;
|
|
|
|
opts->options = 0;
|
|
|
|
*md5 = NULL;
|
|
#ifdef CONFIG_TCP_MD5SIG
|
|
if (static_branch_unlikely(&tcp_md5_needed) &&
|
|
rcu_access_pointer(tp->md5sig_info)) {
|
|
*md5 = tp->af_specific->md5_lookup(sk, sk);
|
|
if (*md5) {
|
|
opts->options |= OPTION_MD5;
|
|
size += TCPOLEN_MD5SIG_ALIGNED;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
if (likely(tp->rx_opt.tstamp_ok)) {
|
|
opts->options |= OPTION_TS;
|
|
opts->tsval = skb ? tcp_skb_timestamp(skb) + tp->tsoffset : 0;
|
|
opts->tsecr = tp->rx_opt.ts_recent;
|
|
size += TCPOLEN_TSTAMP_ALIGNED;
|
|
}
|
|
|
|
/* MPTCP options have precedence over SACK for the limited TCP
|
|
* option space because a MPTCP connection would be forced to
|
|
* fall back to regular TCP if a required multipath option is
|
|
* missing. SACK still gets a chance to use whatever space is
|
|
* left.
|
|
*/
|
|
if (sk_is_mptcp(sk)) {
|
|
unsigned int remaining = MAX_TCP_OPTION_SPACE - size;
|
|
unsigned int opt_size = 0;
|
|
|
|
if (mptcp_established_options(sk, skb, &opt_size, remaining,
|
|
&opts->mptcp)) {
|
|
opts->options |= OPTION_MPTCP;
|
|
size += opt_size;
|
|
}
|
|
}
|
|
|
|
eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack;
|
|
if (unlikely(eff_sacks)) {
|
|
const unsigned int remaining = MAX_TCP_OPTION_SPACE - size;
|
|
if (unlikely(remaining < TCPOLEN_SACK_BASE_ALIGNED +
|
|
TCPOLEN_SACK_PERBLOCK))
|
|
return size;
|
|
|
|
opts->num_sack_blocks =
|
|
min_t(unsigned int, eff_sacks,
|
|
(remaining - TCPOLEN_SACK_BASE_ALIGNED) /
|
|
TCPOLEN_SACK_PERBLOCK);
|
|
|
|
size += TCPOLEN_SACK_BASE_ALIGNED +
|
|
opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK;
|
|
}
|
|
|
|
if (unlikely(BPF_SOCK_OPS_TEST_FLAG(tp,
|
|
BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG))) {
|
|
unsigned int remaining = MAX_TCP_OPTION_SPACE - size;
|
|
|
|
bpf_skops_hdr_opt_len(sk, skb, NULL, NULL, 0, opts, &remaining);
|
|
|
|
size = MAX_TCP_OPTION_SPACE - remaining;
|
|
}
|
|
|
|
return size;
|
|
}
|
|
|
|
|
|
/* TCP SMALL QUEUES (TSQ)
|
|
*
|
|
* TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev)
|
|
* to reduce RTT and bufferbloat.
|
|
* We do this using a special skb destructor (tcp_wfree).
|
|
*
|
|
* Its important tcp_wfree() can be replaced by sock_wfree() in the event skb
|
|
* needs to be reallocated in a driver.
|
|
* The invariant being skb->truesize subtracted from sk->sk_wmem_alloc
|
|
*
|
|
* Since transmit from skb destructor is forbidden, we use a tasklet
|
|
* to process all sockets that eventually need to send more skbs.
|
|
* We use one tasklet per cpu, with its own queue of sockets.
|
|
*/
|
|
struct tsq_tasklet {
|
|
struct tasklet_struct tasklet;
|
|
struct list_head head; /* queue of tcp sockets */
|
|
};
|
|
static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet);
|
|
|
|
static void tcp_tsq_write(struct sock *sk)
|
|
{
|
|
if ((1 << sk->sk_state) &
|
|
(TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING |
|
|
TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) {
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
|
|
if (tp->lost_out > tp->retrans_out &&
|
|
tp->snd_cwnd > tcp_packets_in_flight(tp)) {
|
|
tcp_mstamp_refresh(tp);
|
|
tcp_xmit_retransmit_queue(sk);
|
|
}
|
|
|
|
tcp_write_xmit(sk, tcp_current_mss(sk), tp->nonagle,
|
|
0, GFP_ATOMIC);
|
|
}
|
|
}
|
|
|
|
static void tcp_tsq_handler(struct sock *sk)
|
|
{
|
|
bh_lock_sock(sk);
|
|
if (!sock_owned_by_user(sk))
|
|
tcp_tsq_write(sk);
|
|
else if (!test_and_set_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags))
|
|
sock_hold(sk);
|
|
bh_unlock_sock(sk);
|
|
}
|
|
/*
|
|
* One tasklet per cpu tries to send more skbs.
|
|
* We run in tasklet context but need to disable irqs when
|
|
* transferring tsq->head because tcp_wfree() might
|
|
* interrupt us (non NAPI drivers)
|
|
*/
|
|
static void tcp_tasklet_func(struct tasklet_struct *t)
|
|
{
|
|
struct tsq_tasklet *tsq = from_tasklet(tsq, t, tasklet);
|
|
LIST_HEAD(list);
|
|
unsigned long flags;
|
|
struct list_head *q, *n;
|
|
struct tcp_sock *tp;
|
|
struct sock *sk;
|
|
|
|
local_irq_save(flags);
|
|
list_splice_init(&tsq->head, &list);
|
|
local_irq_restore(flags);
|
|
|
|
list_for_each_safe(q, n, &list) {
|
|
tp = list_entry(q, struct tcp_sock, tsq_node);
|
|
list_del(&tp->tsq_node);
|
|
|
|
sk = (struct sock *)tp;
|
|
smp_mb__before_atomic();
|
|
clear_bit(TSQ_QUEUED, &sk->sk_tsq_flags);
|
|
|
|
tcp_tsq_handler(sk);
|
|
sk_free(sk);
|
|
}
|
|
}
|
|
|
|
#define TCP_DEFERRED_ALL (TCPF_TSQ_DEFERRED | \
|
|
TCPF_WRITE_TIMER_DEFERRED | \
|
|
TCPF_DELACK_TIMER_DEFERRED | \
|
|
TCPF_MTU_REDUCED_DEFERRED)
|
|
/**
|
|
* tcp_release_cb - tcp release_sock() callback
|
|
* @sk: socket
|
|
*
|
|
* called from release_sock() to perform protocol dependent
|
|
* actions before socket release.
|
|
*/
|
|
void tcp_release_cb(struct sock *sk)
|
|
{
|
|
unsigned long flags, nflags;
|
|
|
|
/* perform an atomic operation only if at least one flag is set */
|
|
do {
|
|
flags = sk->sk_tsq_flags;
|
|
if (!(flags & TCP_DEFERRED_ALL))
|
|
return;
|
|
nflags = flags & ~TCP_DEFERRED_ALL;
|
|
} while (cmpxchg(&sk->sk_tsq_flags, flags, nflags) != flags);
|
|
|
|
if (flags & TCPF_TSQ_DEFERRED) {
|
|
tcp_tsq_write(sk);
|
|
__sock_put(sk);
|
|
}
|
|
/* Here begins the tricky part :
|
|
* We are called from release_sock() with :
|
|
* 1) BH disabled
|
|
* 2) sk_lock.slock spinlock held
|
|
* 3) socket owned by us (sk->sk_lock.owned == 1)
|
|
*
|
|
* But following code is meant to be called from BH handlers,
|
|
* so we should keep BH disabled, but early release socket ownership
|
|
*/
|
|
sock_release_ownership(sk);
|
|
|
|
if (flags & TCPF_WRITE_TIMER_DEFERRED) {
|
|
tcp_write_timer_handler(sk);
|
|
__sock_put(sk);
|
|
}
|
|
if (flags & TCPF_DELACK_TIMER_DEFERRED) {
|
|
tcp_delack_timer_handler(sk);
|
|
__sock_put(sk);
|
|
}
|
|
if (flags & TCPF_MTU_REDUCED_DEFERRED) {
|
|
inet_csk(sk)->icsk_af_ops->mtu_reduced(sk);
|
|
__sock_put(sk);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(tcp_release_cb);
|
|
|
|
void __init tcp_tasklet_init(void)
|
|
{
|
|
int i;
|
|
|
|
for_each_possible_cpu(i) {
|
|
struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i);
|
|
|
|
INIT_LIST_HEAD(&tsq->head);
|
|
tasklet_setup(&tsq->tasklet, tcp_tasklet_func);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Write buffer destructor automatically called from kfree_skb.
|
|
* We can't xmit new skbs from this context, as we might already
|
|
* hold qdisc lock.
|
|
*/
|
|
void tcp_wfree(struct sk_buff *skb)
|
|
{
|
|
struct sock *sk = skb->sk;
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
unsigned long flags, nval, oval;
|
|
|
|
/* Keep one reference on sk_wmem_alloc.
|
|
* Will be released by sk_free() from here or tcp_tasklet_func()
|
|
*/
|
|
WARN_ON(refcount_sub_and_test(skb->truesize - 1, &sk->sk_wmem_alloc));
|
|
|
|
/* If this softirq is serviced by ksoftirqd, we are likely under stress.
|
|
* Wait until our queues (qdisc + devices) are drained.
|
|
* This gives :
|
|
* - less callbacks to tcp_write_xmit(), reducing stress (batches)
|
|
* - chance for incoming ACK (processed by another cpu maybe)
|
|
* to migrate this flow (skb->ooo_okay will be eventually set)
|
|
*/
|
|
if (refcount_read(&sk->sk_wmem_alloc) >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current)
|
|
goto out;
|
|
|
|
for (oval = READ_ONCE(sk->sk_tsq_flags);; oval = nval) {
|
|
struct tsq_tasklet *tsq;
|
|
bool empty;
|
|
|
|
if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED))
|
|
goto out;
|
|
|
|
nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED;
|
|
nval = cmpxchg(&sk->sk_tsq_flags, oval, nval);
|
|
if (nval != oval)
|
|
continue;
|
|
|
|
/* queue this socket to tasklet queue */
|
|
local_irq_save(flags);
|
|
tsq = this_cpu_ptr(&tsq_tasklet);
|
|
empty = list_empty(&tsq->head);
|
|
list_add(&tp->tsq_node, &tsq->head);
|
|
if (empty)
|
|
tasklet_schedule(&tsq->tasklet);
|
|
local_irq_restore(flags);
|
|
return;
|
|
}
|
|
out:
|
|
sk_free(sk);
|
|
}
|
|
|
|
/* Note: Called under soft irq.
|
|
* We can call TCP stack right away, unless socket is owned by user.
|
|
*/
|
|
enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer)
|
|
{
|
|
struct tcp_sock *tp = container_of(timer, struct tcp_sock, pacing_timer);
|
|
struct sock *sk = (struct sock *)tp;
|
|
|
|
tcp_tsq_handler(sk);
|
|
sock_put(sk);
|
|
|
|
return HRTIMER_NORESTART;
|
|
}
|
|
|
|
static void tcp_update_skb_after_send(struct sock *sk, struct sk_buff *skb,
|
|
u64 prior_wstamp)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
|
|
if (sk->sk_pacing_status != SK_PACING_NONE) {
|
|
unsigned long rate = sk->sk_pacing_rate;
|
|
|
|
/* Original sch_fq does not pace first 10 MSS
|
|
* Note that tp->data_segs_out overflows after 2^32 packets,
|
|
* this is a minor annoyance.
|
|
*/
|
|
if (rate != ~0UL && rate && tp->data_segs_out >= 10) {
|
|
u64 len_ns = div64_ul((u64)skb->len * NSEC_PER_SEC, rate);
|
|
u64 credit = tp->tcp_wstamp_ns - prior_wstamp;
|
|
|
|
/* take into account OS jitter */
|
|
len_ns -= min_t(u64, len_ns / 2, credit);
|
|
tp->tcp_wstamp_ns += len_ns;
|
|
}
|
|
}
|
|
list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue);
|
|
}
|
|
|
|
INDIRECT_CALLABLE_DECLARE(int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl));
|
|
INDIRECT_CALLABLE_DECLARE(int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl));
|
|
INDIRECT_CALLABLE_DECLARE(void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb));
|
|
|
|
/* This routine actually transmits TCP packets queued in by
|
|
* tcp_do_sendmsg(). This is used by both the initial
|
|
* transmission and possible later retransmissions.
|
|
* All SKB's seen here are completely headerless. It is our
|
|
* job to build the TCP header, and pass the packet down to
|
|
* IP so it can do the same plus pass the packet off to the
|
|
* device.
|
|
*
|
|
* We are working here with either a clone of the original
|
|
* SKB, or a fresh unique copy made by the retransmit engine.
|
|
*/
|
|
static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
|
|
int clone_it, gfp_t gfp_mask, u32 rcv_nxt)
|
|
{
|
|
const struct inet_connection_sock *icsk = inet_csk(sk);
|
|
struct inet_sock *inet;
|
|
struct tcp_sock *tp;
|
|
struct tcp_skb_cb *tcb;
|
|
struct tcp_out_options opts;
|
|
unsigned int tcp_options_size, tcp_header_size;
|
|
struct sk_buff *oskb = NULL;
|
|
struct tcp_md5sig_key *md5;
|
|
struct tcphdr *th;
|
|
u64 prior_wstamp;
|
|
int err;
|
|
|
|
BUG_ON(!skb || !tcp_skb_pcount(skb));
|
|
tp = tcp_sk(sk);
|
|
prior_wstamp = tp->tcp_wstamp_ns;
|
|
tp->tcp_wstamp_ns = max(tp->tcp_wstamp_ns, tp->tcp_clock_cache);
|
|
skb->skb_mstamp_ns = tp->tcp_wstamp_ns;
|
|
if (clone_it) {
|
|
TCP_SKB_CB(skb)->tx.in_flight = TCP_SKB_CB(skb)->end_seq
|
|
- tp->snd_una;
|
|
oskb = skb;
|
|
|
|
tcp_skb_tsorted_save(oskb) {
|
|
if (unlikely(skb_cloned(oskb)))
|
|
skb = pskb_copy(oskb, gfp_mask);
|
|
else
|
|
skb = skb_clone(oskb, gfp_mask);
|
|
} tcp_skb_tsorted_restore(oskb);
|
|
|
|
if (unlikely(!skb))
|
|
return -ENOBUFS;
|
|
/* retransmit skbs might have a non zero value in skb->dev
|
|
* because skb->dev is aliased with skb->rbnode.rb_left
|
|
*/
|
|
skb->dev = NULL;
|
|
}
|
|
|
|
inet = inet_sk(sk);
|
|
tcb = TCP_SKB_CB(skb);
|
|
memset(&opts, 0, sizeof(opts));
|
|
|
|
if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) {
|
|
tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5);
|
|
} else {
|
|
tcp_options_size = tcp_established_options(sk, skb, &opts,
|
|
&md5);
|
|
/* Force a PSH flag on all (GSO) packets to expedite GRO flush
|
|
* at receiver : This slightly improve GRO performance.
|
|
* Note that we do not force the PSH flag for non GSO packets,
|
|
* because they might be sent under high congestion events,
|
|
* and in this case it is better to delay the delivery of 1-MSS
|
|
* packets and thus the corresponding ACK packet that would
|
|
* release the following packet.
|
|
*/
|
|
if (tcp_skb_pcount(skb) > 1)
|
|
tcb->tcp_flags |= TCPHDR_PSH;
|
|
}
|
|
tcp_header_size = tcp_options_size + sizeof(struct tcphdr);
|
|
|
|
/* if no packet is in qdisc/device queue, then allow XPS to select
|
|
* another queue. We can be called from tcp_tsq_handler()
|
|
* which holds one reference to sk.
|
|
*
|
|
* TODO: Ideally, in-flight pure ACK packets should not matter here.
|
|
* One way to get this would be to set skb->truesize = 2 on them.
|
|
*/
|
|
skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1);
|
|
|
|
/* If we had to use memory reserve to allocate this skb,
|
|
* this might cause drops if packet is looped back :
|
|
* Other socket might not have SOCK_MEMALLOC.
|
|
* Packets not looped back do not care about pfmemalloc.
|
|
*/
|
|
skb->pfmemalloc = 0;
|
|
|
|
skb_push(skb, tcp_header_size);
|
|
skb_reset_transport_header(skb);
|
|
|
|
skb_orphan(skb);
|
|
skb->sk = sk;
|
|
skb->destructor = skb_is_tcp_pure_ack(skb) ? __sock_wfree : tcp_wfree;
|
|
refcount_add(skb->truesize, &sk->sk_wmem_alloc);
|
|
|
|
skb_set_dst_pending_confirm(skb, sk->sk_dst_pending_confirm);
|
|
|
|
/* Build TCP header and checksum it. */
|
|
th = (struct tcphdr *)skb->data;
|
|
th->source = inet->inet_sport;
|
|
th->dest = inet->inet_dport;
|
|
th->seq = htonl(tcb->seq);
|
|
th->ack_seq = htonl(rcv_nxt);
|
|
*(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) |
|
|
tcb->tcp_flags);
|
|
|
|
th->check = 0;
|
|
th->urg_ptr = 0;
|
|
|
|
/* The urg_mode check is necessary during a below snd_una win probe */
|
|
if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) {
|
|
if (before(tp->snd_up, tcb->seq + 0x10000)) {
|
|
th->urg_ptr = htons(tp->snd_up - tcb->seq);
|
|
th->urg = 1;
|
|
} else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) {
|
|
th->urg_ptr = htons(0xFFFF);
|
|
th->urg = 1;
|
|
}
|
|
}
|
|
|
|
skb_shinfo(skb)->gso_type = sk->sk_gso_type;
|
|
if (likely(!(tcb->tcp_flags & TCPHDR_SYN))) {
|
|
th->window = htons(tcp_select_window(sk));
|
|
tcp_ecn_send(sk, skb, th, tcp_header_size);
|
|
} else {
|
|
/* RFC1323: The window in SYN & SYN/ACK segments
|
|
* is never scaled.
|
|
*/
|
|
th->window = htons(min(tp->rcv_wnd, 65535U));
|
|
}
|
|
|
|
tcp_options_write((__be32 *)(th + 1), tp, &opts);
|
|
|
|
#ifdef CONFIG_TCP_MD5SIG
|
|
/* Calculate the MD5 hash, as we have all we need now */
|
|
if (md5) {
|
|
sk_nocaps_add(sk, NETIF_F_GSO_MASK);
|
|
tp->af_specific->calc_md5_hash(opts.hash_location,
|
|
md5, sk, skb);
|
|
}
|
|
#endif
|
|
|
|
/* BPF prog is the last one writing header option */
|
|
bpf_skops_write_hdr_opt(sk, skb, NULL, NULL, 0, &opts);
|
|
|
|
INDIRECT_CALL_INET(icsk->icsk_af_ops->send_check,
|
|
tcp_v6_send_check, tcp_v4_send_check,
|
|
sk, skb);
|
|
|
|
if (likely(tcb->tcp_flags & TCPHDR_ACK))
|
|
tcp_event_ack_sent(sk, tcp_skb_pcount(skb), rcv_nxt);
|
|
|
|
if (skb->len != tcp_header_size) {
|
|
tcp_event_data_sent(tp, sk);
|
|
tp->data_segs_out += tcp_skb_pcount(skb);
|
|
tp->bytes_sent += skb->len - tcp_header_size;
|
|
}
|
|
|
|
if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq)
|
|
TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS,
|
|
tcp_skb_pcount(skb));
|
|
|
|
tp->segs_out += tcp_skb_pcount(skb);
|
|
skb_set_hash_from_sk(skb, sk);
|
|
/* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */
|
|
skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb);
|
|
skb_shinfo(skb)->gso_size = tcp_skb_mss(skb);
|
|
|
|
/* Leave earliest departure time in skb->tstamp (skb->skb_mstamp_ns) */
|
|
|
|
/* Cleanup our debris for IP stacks */
|
|
memset(skb->cb, 0, max(sizeof(struct inet_skb_parm),
|
|
sizeof(struct inet6_skb_parm)));
|
|
|
|
tcp_add_tx_delay(skb, tp);
|
|
|
|
err = INDIRECT_CALL_INET(icsk->icsk_af_ops->queue_xmit,
|
|
inet6_csk_xmit, ip_queue_xmit,
|
|
sk, skb, &inet->cork.fl);
|
|
|
|
if (unlikely(err > 0)) {
|
|
tcp_enter_cwr(sk);
|
|
err = net_xmit_eval(err);
|
|
}
|
|
if (!err && oskb) {
|
|
tcp_update_skb_after_send(sk, oskb, prior_wstamp);
|
|
tcp_rate_skb_sent(sk, oskb);
|
|
}
|
|
return err;
|
|
}
|
|
|
|
static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
|
|
gfp_t gfp_mask)
|
|
{
|
|
return __tcp_transmit_skb(sk, skb, clone_it, gfp_mask,
|
|
tcp_sk(sk)->rcv_nxt);
|
|
}
|
|
|
|
/* This routine just queues the buffer for sending.
|
|
*
|
|
* NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames,
|
|
* otherwise socket can stall.
|
|
*/
|
|
static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
|
|
/* Advance write_seq and place onto the write_queue. */
|
|
WRITE_ONCE(tp->write_seq, TCP_SKB_CB(skb)->end_seq);
|
|
__skb_header_release(skb);
|
|
tcp_add_write_queue_tail(sk, skb);
|
|
sk_wmem_queued_add(sk, skb->truesize);
|
|
sk_mem_charge(sk, skb->truesize);
|
|
}
|
|
|
|
/* Initialize TSO segments for a packet. */
|
|
static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now)
|
|
{
|
|
if (skb->len <= mss_now) {
|
|
/* Avoid the costly divide in the normal
|
|
* non-TSO case.
|
|
*/
|
|
tcp_skb_pcount_set(skb, 1);
|
|
TCP_SKB_CB(skb)->tcp_gso_size = 0;
|
|
} else {
|
|
tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now));
|
|
TCP_SKB_CB(skb)->tcp_gso_size = mss_now;
|
|
}
|
|
}
|
|
|
|
/* Pcount in the middle of the write queue got changed, we need to do various
|
|
* tweaks to fix counters
|
|
*/
|
|
static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
|
|
tp->packets_out -= decr;
|
|
|
|
if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)
|
|
tp->sacked_out -= decr;
|
|
if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS)
|
|
tp->retrans_out -= decr;
|
|
if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST)
|
|
tp->lost_out -= decr;
|
|
|
|
/* Reno case is special. Sigh... */
|
|
if (tcp_is_reno(tp) && decr > 0)
|
|
tp->sacked_out -= min_t(u32, tp->sacked_out, decr);
|
|
|
|
if (tp->lost_skb_hint &&
|
|
before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) &&
|
|
(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))
|
|
tp->lost_cnt_hint -= decr;
|
|
|
|
tcp_verify_left_out(tp);
|
|
}
|
|
|
|
static bool tcp_has_tx_tstamp(const struct sk_buff *skb)
|
|
{
|
|
return TCP_SKB_CB(skb)->txstamp_ack ||
|
|
(skb_shinfo(skb)->tx_flags & SKBTX_ANY_TSTAMP);
|
|
}
|
|
|
|
static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2)
|
|
{
|
|
struct skb_shared_info *shinfo = skb_shinfo(skb);
|
|
|
|
if (unlikely(tcp_has_tx_tstamp(skb)) &&
|
|
!before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) {
|
|
struct skb_shared_info *shinfo2 = skb_shinfo(skb2);
|
|
u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP;
|
|
|
|
shinfo->tx_flags &= ~tsflags;
|
|
shinfo2->tx_flags |= tsflags;
|
|
swap(shinfo->tskey, shinfo2->tskey);
|
|
TCP_SKB_CB(skb2)->txstamp_ack = TCP_SKB_CB(skb)->txstamp_ack;
|
|
TCP_SKB_CB(skb)->txstamp_ack = 0;
|
|
}
|
|
}
|
|
|
|
static void tcp_skb_fragment_eor(struct sk_buff *skb, struct sk_buff *skb2)
|
|
{
|
|
TCP_SKB_CB(skb2)->eor = TCP_SKB_CB(skb)->eor;
|
|
TCP_SKB_CB(skb)->eor = 0;
|
|
}
|
|
|
|
/* Insert buff after skb on the write or rtx queue of sk. */
|
|
static void tcp_insert_write_queue_after(struct sk_buff *skb,
|
|
struct sk_buff *buff,
|
|
struct sock *sk,
|
|
enum tcp_queue tcp_queue)
|
|
{
|
|
if (tcp_queue == TCP_FRAG_IN_WRITE_QUEUE)
|
|
__skb_queue_after(&sk->sk_write_queue, skb, buff);
|
|
else
|
|
tcp_rbtree_insert(&sk->tcp_rtx_queue, buff);
|
|
}
|
|
|
|
/* Function to create two new TCP segments. Shrinks the given segment
|
|
* to the specified size and appends a new segment with the rest of the
|
|
* packet to the list. This won't be called frequently, I hope.
|
|
* Remember, these are still headerless SKBs at this point.
|
|
*/
|
|
int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
|
|
struct sk_buff *skb, u32 len,
|
|
unsigned int mss_now, gfp_t gfp)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct sk_buff *buff;
|
|
int nsize, old_factor;
|
|
long limit;
|
|
int nlen;
|
|
u8 flags;
|
|
|
|
if (WARN_ON(len > skb->len))
|
|
return -EINVAL;
|
|
|
|
nsize = skb_headlen(skb) - len;
|
|
if (nsize < 0)
|
|
nsize = 0;
|
|
|
|
/* tcp_sendmsg() can overshoot sk_wmem_queued by one full size skb.
|
|
* We need some allowance to not penalize applications setting small
|
|
* SO_SNDBUF values.
|
|
* Also allow first and last skb in retransmit queue to be split.
|
|
*/
|
|
limit = sk->sk_sndbuf + 2 * SKB_TRUESIZE(GSO_MAX_SIZE);
|
|
if (unlikely((sk->sk_wmem_queued >> 1) > limit &&
|
|
tcp_queue != TCP_FRAG_IN_WRITE_QUEUE &&
|
|
skb != tcp_rtx_queue_head(sk) &&
|
|
skb != tcp_rtx_queue_tail(sk))) {
|
|
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPWQUEUETOOBIG);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
if (skb_unclone(skb, gfp))
|
|
return -ENOMEM;
|
|
|
|
/* Get a new skb... force flag on. */
|
|
buff = sk_stream_alloc_skb(sk, nsize, gfp, true);
|
|
if (!buff)
|
|
return -ENOMEM; /* We'll just try again later. */
|
|
skb_copy_decrypted(buff, skb);
|
|
mptcp_skb_ext_copy(buff, skb);
|
|
|
|
sk_wmem_queued_add(sk, buff->truesize);
|
|
sk_mem_charge(sk, buff->truesize);
|
|
nlen = skb->len - len - nsize;
|
|
buff->truesize += nlen;
|
|
skb->truesize -= nlen;
|
|
|
|
/* Correct the sequence numbers. */
|
|
TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len;
|
|
TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq;
|
|
TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq;
|
|
|
|
/* PSH and FIN should only be set in the second packet. */
|
|
flags = TCP_SKB_CB(skb)->tcp_flags;
|
|
TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH);
|
|
TCP_SKB_CB(buff)->tcp_flags = flags;
|
|
TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked;
|
|
tcp_skb_fragment_eor(skb, buff);
|
|
|
|
skb_split(skb, buff, len);
|
|
|
|
buff->ip_summed = CHECKSUM_PARTIAL;
|
|
|
|
buff->tstamp = skb->tstamp;
|
|
tcp_fragment_tstamp(skb, buff);
|
|
|
|
old_factor = tcp_skb_pcount(skb);
|
|
|
|
/* Fix up tso_factor for both original and new SKB. */
|
|
tcp_set_skb_tso_segs(skb, mss_now);
|
|
tcp_set_skb_tso_segs(buff, mss_now);
|
|
|
|
/* Update delivered info for the new segment */
|
|
TCP_SKB_CB(buff)->tx = TCP_SKB_CB(skb)->tx;
|
|
|
|
/* If this packet has been sent out already, we must
|
|
* adjust the various packet counters.
|
|
*/
|
|
if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) {
|
|
int diff = old_factor - tcp_skb_pcount(skb) -
|
|
tcp_skb_pcount(buff);
|
|
|
|
if (diff)
|
|
tcp_adjust_pcount(sk, skb, diff);
|
|
}
|
|
|
|
/* Link BUFF into the send queue. */
|
|
__skb_header_release(buff);
|
|
tcp_insert_write_queue_after(skb, buff, sk, tcp_queue);
|
|
if (tcp_queue == TCP_FRAG_IN_RTX_QUEUE)
|
|
list_add(&buff->tcp_tsorted_anchor, &skb->tcp_tsorted_anchor);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* This is similar to __pskb_pull_tail(). The difference is that pulled
|
|
* data is not copied, but immediately discarded.
|
|
*/
|
|
static int __pskb_trim_head(struct sk_buff *skb, int len)
|
|
{
|
|
struct skb_shared_info *shinfo;
|
|
int i, k, eat;
|
|
|
|
eat = min_t(int, len, skb_headlen(skb));
|
|
if (eat) {
|
|
__skb_pull(skb, eat);
|
|
len -= eat;
|
|
if (!len)
|
|
return 0;
|
|
}
|
|
eat = len;
|
|
k = 0;
|
|
shinfo = skb_shinfo(skb);
|
|
for (i = 0; i < shinfo->nr_frags; i++) {
|
|
int size = skb_frag_size(&shinfo->frags[i]);
|
|
|
|
if (size <= eat) {
|
|
skb_frag_unref(skb, i);
|
|
eat -= size;
|
|
} else {
|
|
shinfo->frags[k] = shinfo->frags[i];
|
|
if (eat) {
|
|
skb_frag_off_add(&shinfo->frags[k], eat);
|
|
skb_frag_size_sub(&shinfo->frags[k], eat);
|
|
eat = 0;
|
|
}
|
|
k++;
|
|
}
|
|
}
|
|
shinfo->nr_frags = k;
|
|
|
|
skb->data_len -= len;
|
|
skb->len = skb->data_len;
|
|
return len;
|
|
}
|
|
|
|
/* Remove acked data from a packet in the transmit queue. */
|
|
int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
|
|
{
|
|
u32 delta_truesize;
|
|
|
|
if (skb_unclone(skb, GFP_ATOMIC))
|
|
return -ENOMEM;
|
|
|
|
delta_truesize = __pskb_trim_head(skb, len);
|
|
|
|
TCP_SKB_CB(skb)->seq += len;
|
|
skb->ip_summed = CHECKSUM_PARTIAL;
|
|
|
|
if (delta_truesize) {
|
|
skb->truesize -= delta_truesize;
|
|
sk_wmem_queued_add(sk, -delta_truesize);
|
|
sk_mem_uncharge(sk, delta_truesize);
|
|
}
|
|
|
|
/* Any change of skb->len requires recalculation of tso factor. */
|
|
if (tcp_skb_pcount(skb) > 1)
|
|
tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb));
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* Calculate MSS not accounting any TCP options. */
|
|
static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu)
|
|
{
|
|
const struct tcp_sock *tp = tcp_sk(sk);
|
|
const struct inet_connection_sock *icsk = inet_csk(sk);
|
|
int mss_now;
|
|
|
|
/* Calculate base mss without TCP options:
|
|
It is MMS_S - sizeof(tcphdr) of rfc1122
|
|
*/
|
|
mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr);
|
|
|
|
/* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */
|
|
if (icsk->icsk_af_ops->net_frag_header_len) {
|
|
const struct dst_entry *dst = __sk_dst_get(sk);
|
|
|
|
if (dst && dst_allfrag(dst))
|
|
mss_now -= icsk->icsk_af_ops->net_frag_header_len;
|
|
}
|
|
|
|
/* Clamp it (mss_clamp does not include tcp options) */
|
|
if (mss_now > tp->rx_opt.mss_clamp)
|
|
mss_now = tp->rx_opt.mss_clamp;
|
|
|
|
/* Now subtract optional transport overhead */
|
|
mss_now -= icsk->icsk_ext_hdr_len;
|
|
|
|
/* Then reserve room for full set of TCP options and 8 bytes of data */
|
|
mss_now = max(mss_now, sock_net(sk)->ipv4.sysctl_tcp_min_snd_mss);
|
|
return mss_now;
|
|
}
|
|
|
|
/* Calculate MSS. Not accounting for SACKs here. */
|
|
int tcp_mtu_to_mss(struct sock *sk, int pmtu)
|
|
{
|
|
/* Subtract TCP options size, not including SACKs */
|
|
return __tcp_mtu_to_mss(sk, pmtu) -
|
|
(tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr));
|
|
}
|
|
EXPORT_SYMBOL(tcp_mtu_to_mss);
|
|
|
|
/* Inverse of above */
|
|
int tcp_mss_to_mtu(struct sock *sk, int mss)
|
|
{
|
|
const struct tcp_sock *tp = tcp_sk(sk);
|
|
const struct inet_connection_sock *icsk = inet_csk(sk);
|
|
int mtu;
|
|
|
|
mtu = mss +
|
|
tp->tcp_header_len +
|
|
icsk->icsk_ext_hdr_len +
|
|
icsk->icsk_af_ops->net_header_len;
|
|
|
|
/* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */
|
|
if (icsk->icsk_af_ops->net_frag_header_len) {
|
|
const struct dst_entry *dst = __sk_dst_get(sk);
|
|
|
|
if (dst && dst_allfrag(dst))
|
|
mtu += icsk->icsk_af_ops->net_frag_header_len;
|
|
}
|
|
return mtu;
|
|
}
|
|
EXPORT_SYMBOL(tcp_mss_to_mtu);
|
|
|
|
/* MTU probing init per socket */
|
|
void tcp_mtup_init(struct sock *sk)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
struct net *net = sock_net(sk);
|
|
|
|
icsk->icsk_mtup.enabled = net->ipv4.sysctl_tcp_mtu_probing > 1;
|
|
icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) +
|
|
icsk->icsk_af_ops->net_header_len;
|
|
icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, net->ipv4.sysctl_tcp_base_mss);
|
|
icsk->icsk_mtup.probe_size = 0;
|
|
if (icsk->icsk_mtup.enabled)
|
|
icsk->icsk_mtup.probe_timestamp = tcp_jiffies32;
|
|
}
|
|
EXPORT_SYMBOL(tcp_mtup_init);
|
|
|
|
/* This function synchronize snd mss to current pmtu/exthdr set.
|
|
|
|
tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts
|
|
for TCP options, but includes only bare TCP header.
|
|
|
|
tp->rx_opt.mss_clamp is mss negotiated at connection setup.
|
|
It is minimum of user_mss and mss received with SYN.
|
|
It also does not include TCP options.
|
|
|
|
inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function.
|
|
|
|
tp->mss_cache is current effective sending mss, including
|
|
all tcp options except for SACKs. It is evaluated,
|
|
taking into account current pmtu, but never exceeds
|
|
tp->rx_opt.mss_clamp.
|
|
|
|
NOTE1. rfc1122 clearly states that advertised MSS
|
|
DOES NOT include either tcp or ip options.
|
|
|
|
NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache
|
|
are READ ONLY outside this function. --ANK (980731)
|
|
*/
|
|
unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
int mss_now;
|
|
|
|
if (icsk->icsk_mtup.search_high > pmtu)
|
|
icsk->icsk_mtup.search_high = pmtu;
|
|
|
|
mss_now = tcp_mtu_to_mss(sk, pmtu);
|
|
mss_now = tcp_bound_to_half_wnd(tp, mss_now);
|
|
|
|
/* And store cached results */
|
|
icsk->icsk_pmtu_cookie = pmtu;
|
|
if (icsk->icsk_mtup.enabled)
|
|
mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low));
|
|
tp->mss_cache = mss_now;
|
|
|
|
return mss_now;
|
|
}
|
|
EXPORT_SYMBOL(tcp_sync_mss);
|
|
|
|
/* Compute the current effective MSS, taking SACKs and IP options,
|
|
* and even PMTU discovery events into account.
|
|
*/
|
|
unsigned int tcp_current_mss(struct sock *sk)
|
|
{
|
|
const struct tcp_sock *tp = tcp_sk(sk);
|
|
const struct dst_entry *dst = __sk_dst_get(sk);
|
|
u32 mss_now;
|
|
unsigned int header_len;
|
|
struct tcp_out_options opts;
|
|
struct tcp_md5sig_key *md5;
|
|
|
|
mss_now = tp->mss_cache;
|
|
|
|
if (dst) {
|
|
u32 mtu = dst_mtu(dst);
|
|
if (mtu != inet_csk(sk)->icsk_pmtu_cookie)
|
|
mss_now = tcp_sync_mss(sk, mtu);
|
|
}
|
|
|
|
header_len = tcp_established_options(sk, NULL, &opts, &md5) +
|
|
sizeof(struct tcphdr);
|
|
/* The mss_cache is sized based on tp->tcp_header_len, which assumes
|
|
* some common options. If this is an odd packet (because we have SACK
|
|
* blocks etc) then our calculated header_len will be different, and
|
|
* we have to adjust mss_now correspondingly */
|
|
if (header_len != tp->tcp_header_len) {
|
|
int delta = (int) header_len - tp->tcp_header_len;
|
|
mss_now -= delta;
|
|
}
|
|
|
|
return mss_now;
|
|
}
|
|
|
|
/* RFC2861, slow part. Adjust cwnd, after it was not full during one rto.
|
|
* As additional protections, we do not touch cwnd in retransmission phases,
|
|
* and if application hit its sndbuf limit recently.
|
|
*/
|
|
static void tcp_cwnd_application_limited(struct sock *sk)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
|
|
if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open &&
|
|
sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
|
|
/* Limited by application or receiver window. */
|
|
u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk));
|
|
u32 win_used = max(tp->snd_cwnd_used, init_win);
|
|
if (win_used < tp->snd_cwnd) {
|
|
tp->snd_ssthresh = tcp_current_ssthresh(sk);
|
|
tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1;
|
|
}
|
|
tp->snd_cwnd_used = 0;
|
|
}
|
|
tp->snd_cwnd_stamp = tcp_jiffies32;
|
|
}
|
|
|
|
static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited)
|
|
{
|
|
const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
|
|
/* Track the maximum number of outstanding packets in each
|
|
* window, and remember whether we were cwnd-limited then.
|
|
*/
|
|
if (!before(tp->snd_una, tp->max_packets_seq) ||
|
|
tp->packets_out > tp->max_packets_out ||
|
|
is_cwnd_limited) {
|
|
tp->max_packets_out = tp->packets_out;
|
|
tp->max_packets_seq = tp->snd_nxt;
|
|
tp->is_cwnd_limited = is_cwnd_limited;
|
|
}
|
|
|
|
if (tcp_is_cwnd_limited(sk)) {
|
|
/* Network is feed fully. */
|
|
tp->snd_cwnd_used = 0;
|
|
tp->snd_cwnd_stamp = tcp_jiffies32;
|
|
} else {
|
|
/* Network starves. */
|
|
if (tp->packets_out > tp->snd_cwnd_used)
|
|
tp->snd_cwnd_used = tp->packets_out;
|
|
|
|
if (sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle &&
|
|
(s32)(tcp_jiffies32 - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto &&
|
|
!ca_ops->cong_control)
|
|
tcp_cwnd_application_limited(sk);
|
|
|
|
/* The following conditions together indicate the starvation
|
|
* is caused by insufficient sender buffer:
|
|
* 1) just sent some data (see tcp_write_xmit)
|
|
* 2) not cwnd limited (this else condition)
|
|
* 3) no more data to send (tcp_write_queue_empty())
|
|
* 4) application is hitting buffer limit (SOCK_NOSPACE)
|
|
*/
|
|
if (tcp_write_queue_empty(sk) && sk->sk_socket &&
|
|
test_bit(SOCK_NOSPACE, &sk->sk_socket->flags) &&
|
|
(1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
|
|
tcp_chrono_start(sk, TCP_CHRONO_SNDBUF_LIMITED);
|
|
}
|
|
}
|
|
|
|
/* Minshall's variant of the Nagle send check. */
|
|
static bool tcp_minshall_check(const struct tcp_sock *tp)
|
|
{
|
|
return after(tp->snd_sml, tp->snd_una) &&
|
|
!after(tp->snd_sml, tp->snd_nxt);
|
|
}
|
|
|
|
/* Update snd_sml if this skb is under mss
|
|
* Note that a TSO packet might end with a sub-mss segment
|
|
* The test is really :
|
|
* if ((skb->len % mss) != 0)
|
|
* tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
|
|
* But we can avoid doing the divide again given we already have
|
|
* skb_pcount = skb->len / mss_now
|
|
*/
|
|
static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now,
|
|
const struct sk_buff *skb)
|
|
{
|
|
if (skb->len < tcp_skb_pcount(skb) * mss_now)
|
|
tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
|
|
}
|
|
|
|
/* Return false, if packet can be sent now without violation Nagle's rules:
|
|
* 1. It is full sized. (provided by caller in %partial bool)
|
|
* 2. Or it contains FIN. (already checked by caller)
|
|
* 3. Or TCP_CORK is not set, and TCP_NODELAY is set.
|
|
* 4. Or TCP_CORK is not set, and all sent packets are ACKed.
|
|
* With Minshall's modification: all sent small packets are ACKed.
|
|
*/
|
|
static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp,
|
|
int nonagle)
|
|
{
|
|
return partial &&
|
|
((nonagle & TCP_NAGLE_CORK) ||
|
|
(!nonagle && tp->packets_out && tcp_minshall_check(tp)));
|
|
}
|
|
|
|
/* Return how many segs we'd like on a TSO packet,
|
|
* to send one TSO packet per ms
|
|
*/
|
|
static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
|
|
int min_tso_segs)
|
|
{
|
|
u32 bytes, segs;
|
|
|
|
bytes = min_t(unsigned long,
|
|
sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift),
|
|
sk->sk_gso_max_size - 1 - MAX_TCP_HEADER);
|
|
|
|
/* Goal is to send at least one packet per ms,
|
|
* not one big TSO packet every 100 ms.
|
|
* This preserves ACK clocking and is consistent
|
|
* with tcp_tso_should_defer() heuristic.
|
|
*/
|
|
segs = max_t(u32, bytes / mss_now, min_tso_segs);
|
|
|
|
return segs;
|
|
}
|
|
|
|
/* Return the number of segments we want in the skb we are transmitting.
|
|
* See if congestion control module wants to decide; otherwise, autosize.
|
|
*/
|
|
static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now)
|
|
{
|
|
const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
|
|
u32 min_tso, tso_segs;
|
|
|
|
min_tso = ca_ops->min_tso_segs ?
|
|
ca_ops->min_tso_segs(sk) :
|
|
sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs;
|
|
|
|
tso_segs = tcp_tso_autosize(sk, mss_now, min_tso);
|
|
return min_t(u32, tso_segs, sk->sk_gso_max_segs);
|
|
}
|
|
|
|
/* Returns the portion of skb which can be sent right away */
|
|
static unsigned int tcp_mss_split_point(const struct sock *sk,
|
|
const struct sk_buff *skb,
|
|
unsigned int mss_now,
|
|
unsigned int max_segs,
|
|
int nonagle)
|
|
{
|
|
const struct tcp_sock *tp = tcp_sk(sk);
|
|
u32 partial, needed, window, max_len;
|
|
|
|
window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq;
|
|
max_len = mss_now * max_segs;
|
|
|
|
if (likely(max_len <= window && skb != tcp_write_queue_tail(sk)))
|
|
return max_len;
|
|
|
|
needed = min(skb->len, window);
|
|
|
|
if (max_len <= needed)
|
|
return max_len;
|
|
|
|
partial = needed % mss_now;
|
|
/* If last segment is not a full MSS, check if Nagle rules allow us
|
|
* to include this last segment in this skb.
|
|
* Otherwise, we'll split the skb at last MSS boundary
|
|
*/
|
|
if (tcp_nagle_check(partial != 0, tp, nonagle))
|
|
return needed - partial;
|
|
|
|
return needed;
|
|
}
|
|
|
|
/* Can at least one segment of SKB be sent right now, according to the
|
|
* congestion window rules? If so, return how many segments are allowed.
|
|
*/
|
|
static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp,
|
|
const struct sk_buff *skb)
|
|
{
|
|
u32 in_flight, cwnd, halfcwnd;
|
|
|
|
/* Don't be strict about the congestion window for the final FIN. */
|
|
if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) &&
|
|
tcp_skb_pcount(skb) == 1)
|
|
return 1;
|
|
|
|
in_flight = tcp_packets_in_flight(tp);
|
|
cwnd = tp->snd_cwnd;
|
|
if (in_flight >= cwnd)
|
|
return 0;
|
|
|
|
/* For better scheduling, ensure we have at least
|
|
* 2 GSO packets in flight.
|
|
*/
|
|
halfcwnd = max(cwnd >> 1, 1U);
|
|
return min(halfcwnd, cwnd - in_flight);
|
|
}
|
|
|
|
/* Initialize TSO state of a skb.
|
|
* This must be invoked the first time we consider transmitting
|
|
* SKB onto the wire.
|
|
*/
|
|
static int tcp_init_tso_segs(struct sk_buff *skb, unsigned int mss_now)
|
|
{
|
|
int tso_segs = tcp_skb_pcount(skb);
|
|
|
|
if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) {
|
|
tcp_set_skb_tso_segs(skb, mss_now);
|
|
tso_segs = tcp_skb_pcount(skb);
|
|
}
|
|
return tso_segs;
|
|
}
|
|
|
|
|
|
/* Return true if the Nagle test allows this packet to be
|
|
* sent now.
|
|
*/
|
|
static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb,
|
|
unsigned int cur_mss, int nonagle)
|
|
{
|
|
/* Nagle rule does not apply to frames, which sit in the middle of the
|
|
* write_queue (they have no chances to get new data).
|
|
*
|
|
* This is implemented in the callers, where they modify the 'nonagle'
|
|
* argument based upon the location of SKB in the send queue.
|
|
*/
|
|
if (nonagle & TCP_NAGLE_PUSH)
|
|
return true;
|
|
|
|
/* Don't use the nagle rule for urgent data (or for the final FIN). */
|
|
if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
|
|
return true;
|
|
|
|
if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/* Does at least the first segment of SKB fit into the send window? */
|
|
static bool tcp_snd_wnd_test(const struct tcp_sock *tp,
|
|
const struct sk_buff *skb,
|
|
unsigned int cur_mss)
|
|
{
|
|
u32 end_seq = TCP_SKB_CB(skb)->end_seq;
|
|
|
|
if (skb->len > cur_mss)
|
|
end_seq = TCP_SKB_CB(skb)->seq + cur_mss;
|
|
|
|
return !after(end_seq, tcp_wnd_end(tp));
|
|
}
|
|
|
|
/* Trim TSO SKB to LEN bytes, put the remaining data into a new packet
|
|
* which is put after SKB on the list. It is very much like
|
|
* tcp_fragment() except that it may make several kinds of assumptions
|
|
* in order to speed up the splitting operation. In particular, we
|
|
* know that all the data is in scatter-gather pages, and that the
|
|
* packet has never been sent out before (and thus is not cloned).
|
|
*/
|
|
static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len,
|
|
unsigned int mss_now, gfp_t gfp)
|
|
{
|
|
int nlen = skb->len - len;
|
|
struct sk_buff *buff;
|
|
u8 flags;
|
|
|
|
/* All of a TSO frame must be composed of paged data. */
|
|
if (skb->len != skb->data_len)
|
|
return tcp_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE,
|
|
skb, len, mss_now, gfp);
|
|
|
|
buff = sk_stream_alloc_skb(sk, 0, gfp, true);
|
|
if (unlikely(!buff))
|
|
return -ENOMEM;
|
|
skb_copy_decrypted(buff, skb);
|
|
mptcp_skb_ext_copy(buff, skb);
|
|
|
|
sk_wmem_queued_add(sk, buff->truesize);
|
|
sk_mem_charge(sk, buff->truesize);
|
|
buff->truesize += nlen;
|
|
skb->truesize -= nlen;
|
|
|
|
/* Correct the sequence numbers. */
|
|
TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len;
|
|
TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq;
|
|
TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq;
|
|
|
|
/* PSH and FIN should only be set in the second packet. */
|
|
flags = TCP_SKB_CB(skb)->tcp_flags;
|
|
TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH);
|
|
TCP_SKB_CB(buff)->tcp_flags = flags;
|
|
|
|
/* This packet was never sent out yet, so no SACK bits. */
|
|
TCP_SKB_CB(buff)->sacked = 0;
|
|
|
|
tcp_skb_fragment_eor(skb, buff);
|
|
|
|
buff->ip_summed = CHECKSUM_PARTIAL;
|
|
skb_split(skb, buff, len);
|
|
tcp_fragment_tstamp(skb, buff);
|
|
|
|
/* Fix up tso_factor for both original and new SKB. */
|
|
tcp_set_skb_tso_segs(skb, mss_now);
|
|
tcp_set_skb_tso_segs(buff, mss_now);
|
|
|
|
/* Link BUFF into the send queue. */
|
|
__skb_header_release(buff);
|
|
tcp_insert_write_queue_after(skb, buff, sk, TCP_FRAG_IN_WRITE_QUEUE);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* Try to defer sending, if possible, in order to minimize the amount
|
|
* of TSO splitting we do. View it as a kind of TSO Nagle test.
|
|
*
|
|
* This algorithm is from John Heffner.
|
|
*/
|
|
static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
|
|
bool *is_cwnd_limited,
|
|
bool *is_rwnd_limited,
|
|
u32 max_segs)
|
|
{
|
|
const struct inet_connection_sock *icsk = inet_csk(sk);
|
|
u32 send_win, cong_win, limit, in_flight;
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct sk_buff *head;
|
|
int win_divisor;
|
|
s64 delta;
|
|
|
|
if (icsk->icsk_ca_state >= TCP_CA_Recovery)
|
|
goto send_now;
|
|
|
|
/* Avoid bursty behavior by allowing defer
|
|
* only if the last write was recent (1 ms).
|
|
* Note that tp->tcp_wstamp_ns can be in the future if we have
|
|
* packets waiting in a qdisc or device for EDT delivery.
|
|
*/
|
|
delta = tp->tcp_clock_cache - tp->tcp_wstamp_ns - NSEC_PER_MSEC;
|
|
if (delta > 0)
|
|
goto send_now;
|
|
|
|
in_flight = tcp_packets_in_flight(tp);
|
|
|
|
BUG_ON(tcp_skb_pcount(skb) <= 1);
|
|
BUG_ON(tp->snd_cwnd <= in_flight);
|
|
|
|
send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq;
|
|
|
|
/* From in_flight test above, we know that cwnd > in_flight. */
|
|
cong_win = (tp->snd_cwnd - in_flight) * tp->mss_cache;
|
|
|
|
limit = min(send_win, cong_win);
|
|
|
|
/* If a full-sized TSO skb can be sent, do it. */
|
|
if (limit >= max_segs * tp->mss_cache)
|
|
goto send_now;
|
|
|
|
/* Middle in queue won't get any more data, full sendable already? */
|
|
if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len))
|
|
goto send_now;
|
|
|
|
win_divisor = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_tso_win_divisor);
|
|
if (win_divisor) {
|
|
u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache);
|
|
|
|
/* If at least some fraction of a window is available,
|
|
* just use it.
|
|
*/
|
|
chunk /= win_divisor;
|
|
if (limit >= chunk)
|
|
goto send_now;
|
|
} else {
|
|
/* Different approach, try not to defer past a single
|
|
* ACK. Receiver should ACK every other full sized
|
|
* frame, so if we have space for more than 3 frames
|
|
* then send now.
|
|
*/
|
|
if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache)
|
|
goto send_now;
|
|
}
|
|
|
|
/* TODO : use tsorted_sent_queue ? */
|
|
head = tcp_rtx_queue_head(sk);
|
|
if (!head)
|
|
goto send_now;
|
|
delta = tp->tcp_clock_cache - head->tstamp;
|
|
/* If next ACK is likely to come too late (half srtt), do not defer */
|
|
if ((s64)(delta - (u64)NSEC_PER_USEC * (tp->srtt_us >> 4)) < 0)
|
|
goto send_now;
|
|
|
|
/* Ok, it looks like it is advisable to defer.
|
|
* Three cases are tracked :
|
|
* 1) We are cwnd-limited
|
|
* 2) We are rwnd-limited
|
|
* 3) We are application limited.
|
|
*/
|
|
if (cong_win < send_win) {
|
|
if (cong_win <= skb->len) {
|
|
*is_cwnd_limited = true;
|
|
return true;
|
|
}
|
|
} else {
|
|
if (send_win <= skb->len) {
|
|
*is_rwnd_limited = true;
|
|
return true;
|
|
}
|
|
}
|
|
|
|
/* If this packet won't get more data, do not wait. */
|
|
if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) ||
|
|
TCP_SKB_CB(skb)->eor)
|
|
goto send_now;
|
|
|
|
return true;
|
|
|
|
send_now:
|
|
return false;
|
|
}
|
|
|
|
static inline void tcp_mtu_check_reprobe(struct sock *sk)
|
|
{
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct net *net = sock_net(sk);
|
|
u32 interval;
|
|
s32 delta;
|
|
|
|
interval = net->ipv4.sysctl_tcp_probe_interval;
|
|
delta = tcp_jiffies32 - icsk->icsk_mtup.probe_timestamp;
|
|
if (unlikely(delta >= interval * HZ)) {
|
|
int mss = tcp_current_mss(sk);
|
|
|
|
/* Update current search range */
|
|
icsk->icsk_mtup.probe_size = 0;
|
|
icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp +
|
|
sizeof(struct tcphdr) +
|
|
icsk->icsk_af_ops->net_header_len;
|
|
icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss);
|
|
|
|
/* Update probe time stamp */
|
|
icsk->icsk_mtup.probe_timestamp = tcp_jiffies32;
|
|
}
|
|
}
|
|
|
|
static bool tcp_can_coalesce_send_queue_head(struct sock *sk, int len)
|
|
{
|
|
struct sk_buff *skb, *next;
|
|
|
|
skb = tcp_send_head(sk);
|
|
tcp_for_write_queue_from_safe(skb, next, sk) {
|
|
if (len <= skb->len)
|
|
break;
|
|
|
|
if (unlikely(TCP_SKB_CB(skb)->eor) || tcp_has_tx_tstamp(skb))
|
|
return false;
|
|
|
|
len -= skb->len;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/* Create a new MTU probe if we are ready.
|
|
* MTU probe is regularly attempting to increase the path MTU by
|
|
* deliberately sending larger packets. This discovers routing
|
|
* changes resulting in larger path MTUs.
|
|
*
|
|
* Returns 0 if we should wait to probe (no cwnd available),
|
|
* 1 if a probe was sent,
|
|
* -1 otherwise
|
|
*/
|
|
static int tcp_mtu_probe(struct sock *sk)
|
|
{
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct sk_buff *skb, *nskb, *next;
|
|
struct net *net = sock_net(sk);
|
|
int probe_size;
|
|
int size_needed;
|
|
int copy, len;
|
|
int mss_now;
|
|
int interval;
|
|
|
|
/* Not currently probing/verifying,
|
|
* not in recovery,
|
|
* have enough cwnd, and
|
|
* not SACKing (the variable headers throw things off)
|
|
*/
|
|
if (likely(!icsk->icsk_mtup.enabled ||
|
|
icsk->icsk_mtup.probe_size ||
|
|
inet_csk(sk)->icsk_ca_state != TCP_CA_Open ||
|
|
tp->snd_cwnd < 11 ||
|
|
tp->rx_opt.num_sacks || tp->rx_opt.dsack))
|
|
return -1;
|
|
|
|
/* Use binary search for probe_size between tcp_mss_base,
|
|
* and current mss_clamp. if (search_high - search_low)
|
|
* smaller than a threshold, backoff from probing.
|
|
*/
|
|
mss_now = tcp_current_mss(sk);
|
|
probe_size = tcp_mtu_to_mss(sk, (icsk->icsk_mtup.search_high +
|
|
icsk->icsk_mtup.search_low) >> 1);
|
|
size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache;
|
|
interval = icsk->icsk_mtup.search_high - icsk->icsk_mtup.search_low;
|
|
/* When misfortune happens, we are reprobing actively,
|
|
* and then reprobe timer has expired. We stick with current
|
|
* probing process by not resetting search range to its orignal.
|
|
*/
|
|
if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high) ||
|
|
interval < net->ipv4.sysctl_tcp_probe_threshold) {
|
|
/* Check whether enough time has elaplased for
|
|
* another round of probing.
|
|
*/
|
|
tcp_mtu_check_reprobe(sk);
|
|
return -1;
|
|
}
|
|
|
|
/* Have enough data in the send queue to probe? */
|
|
if (tp->write_seq - tp->snd_nxt < size_needed)
|
|
return -1;
|
|
|
|
if (tp->snd_wnd < size_needed)
|
|
return -1;
|
|
if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp)))
|
|
return 0;
|
|
|
|
/* Do we need to wait to drain cwnd? With none in flight, don't stall */
|
|
if (tcp_packets_in_flight(tp) + 2 > tp->snd_cwnd) {
|
|
if (!tcp_packets_in_flight(tp))
|
|
return -1;
|
|
else
|
|
return 0;
|
|
}
|
|
|
|
if (!tcp_can_coalesce_send_queue_head(sk, probe_size))
|
|
return -1;
|
|
|
|
/* We're allowed to probe. Build it now. */
|
|
nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC, false);
|
|
if (!nskb)
|
|
return -1;
|
|
sk_wmem_queued_add(sk, nskb->truesize);
|
|
sk_mem_charge(sk, nskb->truesize);
|
|
|
|
skb = tcp_send_head(sk);
|
|
skb_copy_decrypted(nskb, skb);
|
|
mptcp_skb_ext_copy(nskb, skb);
|
|
|
|
TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq;
|
|
TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size;
|
|
TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK;
|
|
TCP_SKB_CB(nskb)->sacked = 0;
|
|
nskb->csum = 0;
|
|
nskb->ip_summed = CHECKSUM_PARTIAL;
|
|
|
|
tcp_insert_write_queue_before(nskb, skb, sk);
|
|
tcp_highest_sack_replace(sk, skb, nskb);
|
|
|
|
len = 0;
|
|
tcp_for_write_queue_from_safe(skb, next, sk) {
|
|
copy = min_t(int, skb->len, probe_size - len);
|
|
skb_copy_bits(skb, 0, skb_put(nskb, copy), copy);
|
|
|
|
if (skb->len <= copy) {
|
|
/* We've eaten all the data from this skb.
|
|
* Throw it away. */
|
|
TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags;
|
|
/* If this is the last SKB we copy and eor is set
|
|
* we need to propagate it to the new skb.
|
|
*/
|
|
TCP_SKB_CB(nskb)->eor = TCP_SKB_CB(skb)->eor;
|
|
tcp_skb_collapse_tstamp(nskb, skb);
|
|
tcp_unlink_write_queue(skb, sk);
|
|
sk_wmem_free_skb(sk, skb);
|
|
} else {
|
|
TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags &
|
|
~(TCPHDR_FIN|TCPHDR_PSH);
|
|
if (!skb_shinfo(skb)->nr_frags) {
|
|
skb_pull(skb, copy);
|
|
} else {
|
|
__pskb_trim_head(skb, copy);
|
|
tcp_set_skb_tso_segs(skb, mss_now);
|
|
}
|
|
TCP_SKB_CB(skb)->seq += copy;
|
|
}
|
|
|
|
len += copy;
|
|
|
|
if (len >= probe_size)
|
|
break;
|
|
}
|
|
tcp_init_tso_segs(nskb, nskb->len);
|
|
|
|
/* We're ready to send. If this fails, the probe will
|
|
* be resegmented into mss-sized pieces by tcp_write_xmit().
|
|
*/
|
|
if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) {
|
|
/* Decrement cwnd here because we are sending
|
|
* effectively two packets. */
|
|
tp->snd_cwnd--;
|
|
tcp_event_new_data_sent(sk, nskb);
|
|
|
|
icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len);
|
|
tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq;
|
|
tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq;
|
|
|
|
return 1;
|
|
}
|
|
|
|
return -1;
|
|
}
|
|
|
|
static bool tcp_pacing_check(struct sock *sk)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
|
|
if (!tcp_needs_internal_pacing(sk))
|
|
return false;
|
|
|
|
if (tp->tcp_wstamp_ns <= tp->tcp_clock_cache)
|
|
return false;
|
|
|
|
if (!hrtimer_is_queued(&tp->pacing_timer)) {
|
|
hrtimer_start(&tp->pacing_timer,
|
|
ns_to_ktime(tp->tcp_wstamp_ns),
|
|
HRTIMER_MODE_ABS_PINNED_SOFT);
|
|
sock_hold(sk);
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/* TCP Small Queues :
|
|
* Control number of packets in qdisc/devices to two packets / or ~1 ms.
|
|
* (These limits are doubled for retransmits)
|
|
* This allows for :
|
|
* - better RTT estimation and ACK scheduling
|
|
* - faster recovery
|
|
* - high rates
|
|
* Alas, some drivers / subsystems require a fair amount
|
|
* of queued bytes to ensure line rate.
|
|
* One example is wifi aggregation (802.11 AMPDU)
|
|
*/
|
|
static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb,
|
|
unsigned int factor)
|
|
{
|
|
unsigned long limit;
|
|
|
|
limit = max_t(unsigned long,
|
|
2 * skb->truesize,
|
|
sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift));
|
|
if (sk->sk_pacing_status == SK_PACING_NONE)
|
|
limit = min_t(unsigned long, limit,
|
|
sock_net(sk)->ipv4.sysctl_tcp_limit_output_bytes);
|
|
limit <<= factor;
|
|
|
|
if (static_branch_unlikely(&tcp_tx_delay_enabled) &&
|
|
tcp_sk(sk)->tcp_tx_delay) {
|
|
u64 extra_bytes = (u64)sk->sk_pacing_rate * tcp_sk(sk)->tcp_tx_delay;
|
|
|
|
/* TSQ is based on skb truesize sum (sk_wmem_alloc), so we
|
|
* approximate our needs assuming an ~100% skb->truesize overhead.
|
|
* USEC_PER_SEC is approximated by 2^20.
|
|
* do_div(extra_bytes, USEC_PER_SEC/2) is replaced by a right shift.
|
|
*/
|
|
extra_bytes >>= (20 - 1);
|
|
limit += extra_bytes;
|
|
}
|
|
if (refcount_read(&sk->sk_wmem_alloc) > limit) {
|
|
/* Always send skb if rtx queue is empty.
|
|
* No need to wait for TX completion to call us back,
|
|
* after softirq/tasklet schedule.
|
|
* This helps when TX completions are delayed too much.
|
|
*/
|
|
if (tcp_rtx_queue_empty(sk))
|
|
return false;
|
|
|
|
set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags);
|
|
/* It is possible TX completion already happened
|
|
* before we set TSQ_THROTTLED, so we must
|
|
* test again the condition.
|
|
*/
|
|
smp_mb__after_atomic();
|
|
if (refcount_read(&sk->sk_wmem_alloc) > limit)
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
static void tcp_chrono_set(struct tcp_sock *tp, const enum tcp_chrono new)
|
|
{
|
|
const u32 now = tcp_jiffies32;
|
|
enum tcp_chrono old = tp->chrono_type;
|
|
|
|
if (old > TCP_CHRONO_UNSPEC)
|
|
tp->chrono_stat[old - 1] += now - tp->chrono_start;
|
|
tp->chrono_start = now;
|
|
tp->chrono_type = new;
|
|
}
|
|
|
|
void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
|
|
/* If there are multiple conditions worthy of tracking in a
|
|
* chronograph then the highest priority enum takes precedence
|
|
* over the other conditions. So that if something "more interesting"
|
|
* starts happening, stop the previous chrono and start a new one.
|
|
*/
|
|
if (type > tp->chrono_type)
|
|
tcp_chrono_set(tp, type);
|
|
}
|
|
|
|
void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
|
|
|
|
/* There are multiple conditions worthy of tracking in a
|
|
* chronograph, so that the highest priority enum takes
|
|
* precedence over the other conditions (see tcp_chrono_start).
|
|
* If a condition stops, we only stop chrono tracking if
|
|
* it's the "most interesting" or current chrono we are
|
|
* tracking and starts busy chrono if we have pending data.
|
|
*/
|
|
if (tcp_rtx_and_write_queues_empty(sk))
|
|
tcp_chrono_set(tp, TCP_CHRONO_UNSPEC);
|
|
else if (type == tp->chrono_type)
|
|
tcp_chrono_set(tp, TCP_CHRONO_BUSY);
|
|
}
|
|
|
|
/* This routine writes packets to the network. It advances the
|
|
* send_head. This happens as incoming acks open up the remote
|
|
* window for us.
|
|
*
|
|
* LARGESEND note: !tcp_urg_mode is overkill, only frames between
|
|
* snd_up-64k-mss .. snd_up cannot be large. However, taking into
|
|
* account rare use of URG, this is not a big flaw.
|
|
*
|
|
* Send at most one packet when push_one > 0. Temporarily ignore
|
|
* cwnd limit to force at most one packet out when push_one == 2.
|
|
|
|
* Returns true, if no segments are in flight and we have queued segments,
|
|
* but cannot send anything now because of SWS or another problem.
|
|
*/
|
|
static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
|
|
int push_one, gfp_t gfp)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct sk_buff *skb;
|
|
unsigned int tso_segs, sent_pkts;
|
|
int cwnd_quota;
|
|
int result;
|
|
bool is_cwnd_limited = false, is_rwnd_limited = false;
|
|
u32 max_segs;
|
|
|
|
sent_pkts = 0;
|
|
|
|
tcp_mstamp_refresh(tp);
|
|
if (!push_one) {
|
|
/* Do MTU probing. */
|
|
result = tcp_mtu_probe(sk);
|
|
if (!result) {
|
|
return false;
|
|
} else if (result > 0) {
|
|
sent_pkts = 1;
|
|
}
|
|
}
|
|
|
|
max_segs = tcp_tso_segs(sk, mss_now);
|
|
while ((skb = tcp_send_head(sk))) {
|
|
unsigned int limit;
|
|
|
|
if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) {
|
|
/* "skb_mstamp_ns" is used as a start point for the retransmit timer */
|
|
skb->skb_mstamp_ns = tp->tcp_wstamp_ns = tp->tcp_clock_cache;
|
|
list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue);
|
|
tcp_init_tso_segs(skb, mss_now);
|
|
goto repair; /* Skip network transmission */
|
|
}
|
|
|
|
if (tcp_pacing_check(sk))
|
|
break;
|
|
|
|
tso_segs = tcp_init_tso_segs(skb, mss_now);
|
|
BUG_ON(!tso_segs);
|
|
|
|
cwnd_quota = tcp_cwnd_test(tp, skb);
|
|
if (!cwnd_quota) {
|
|
if (push_one == 2)
|
|
/* Force out a loss probe pkt. */
|
|
cwnd_quota = 1;
|
|
else
|
|
break;
|
|
}
|
|
|
|
if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) {
|
|
is_rwnd_limited = true;
|
|
break;
|
|
}
|
|
|
|
if (tso_segs == 1) {
|
|
if (unlikely(!tcp_nagle_test(tp, skb, mss_now,
|
|
(tcp_skb_is_last(sk, skb) ?
|
|
nonagle : TCP_NAGLE_PUSH))))
|
|
break;
|
|
} else {
|
|
if (!push_one &&
|
|
tcp_tso_should_defer(sk, skb, &is_cwnd_limited,
|
|
&is_rwnd_limited, max_segs))
|
|
break;
|
|
}
|
|
|
|
limit = mss_now;
|
|
if (tso_segs > 1 && !tcp_urg_mode(tp))
|
|
limit = tcp_mss_split_point(sk, skb, mss_now,
|
|
min_t(unsigned int,
|
|
cwnd_quota,
|
|
max_segs),
|
|
nonagle);
|
|
|
|
if (skb->len > limit &&
|
|
unlikely(tso_fragment(sk, skb, limit, mss_now, gfp)))
|
|
break;
|
|
|
|
if (tcp_small_queue_check(sk, skb, 0))
|
|
break;
|
|
|
|
/* Argh, we hit an empty skb(), presumably a thread
|
|
* is sleeping in sendmsg()/sk_stream_wait_memory().
|
|
* We do not want to send a pure-ack packet and have
|
|
* a strange looking rtx queue with empty packet(s).
|
|
*/
|
|
if (TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq)
|
|
break;
|
|
|
|
if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp)))
|
|
break;
|
|
|
|
repair:
|
|
/* Advance the send_head. This one is sent out.
|
|
* This call will increment packets_out.
|
|
*/
|
|
tcp_event_new_data_sent(sk, skb);
|
|
|
|
tcp_minshall_update(tp, mss_now, skb);
|
|
sent_pkts += tcp_skb_pcount(skb);
|
|
|
|
if (push_one)
|
|
break;
|
|
}
|
|
|
|
if (is_rwnd_limited)
|
|
tcp_chrono_start(sk, TCP_CHRONO_RWND_LIMITED);
|
|
else
|
|
tcp_chrono_stop(sk, TCP_CHRONO_RWND_LIMITED);
|
|
|
|
is_cwnd_limited |= (tcp_packets_in_flight(tp) >= tp->snd_cwnd);
|
|
if (likely(sent_pkts || is_cwnd_limited))
|
|
tcp_cwnd_validate(sk, is_cwnd_limited);
|
|
|
|
if (likely(sent_pkts)) {
|
|
if (tcp_in_cwnd_reduction(sk))
|
|
tp->prr_out += sent_pkts;
|
|
|
|
/* Send one loss probe per tail loss episode. */
|
|
if (push_one != 2)
|
|
tcp_schedule_loss_probe(sk, false);
|
|
return false;
|
|
}
|
|
return !tp->packets_out && !tcp_write_queue_empty(sk);
|
|
}
|
|
|
|
bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto)
|
|
{
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
u32 timeout, rto_delta_us;
|
|
int early_retrans;
|
|
|
|
/* Don't do any loss probe on a Fast Open connection before 3WHS
|
|
* finishes.
|
|
*/
|
|
if (rcu_access_pointer(tp->fastopen_rsk))
|
|
return false;
|
|
|
|
early_retrans = sock_net(sk)->ipv4.sysctl_tcp_early_retrans;
|
|
/* Schedule a loss probe in 2*RTT for SACK capable connections
|
|
* not in loss recovery, that are either limited by cwnd or application.
|
|
*/
|
|
if ((early_retrans != 3 && early_retrans != 4) ||
|
|
!tp->packets_out || !tcp_is_sack(tp) ||
|
|
(icsk->icsk_ca_state != TCP_CA_Open &&
|
|
icsk->icsk_ca_state != TCP_CA_CWR))
|
|
return false;
|
|
|
|
/* Probe timeout is 2*rtt. Add minimum RTO to account
|
|
* for delayed ack when there's one outstanding packet. If no RTT
|
|
* sample is available then probe after TCP_TIMEOUT_INIT.
|
|
*/
|
|
if (tp->srtt_us) {
|
|
timeout = usecs_to_jiffies(tp->srtt_us >> 2);
|
|
if (tp->packets_out == 1)
|
|
timeout += TCP_RTO_MIN;
|
|
else
|
|
timeout += TCP_TIMEOUT_MIN;
|
|
} else {
|
|
timeout = TCP_TIMEOUT_INIT;
|
|
}
|
|
|
|
/* If the RTO formula yields an earlier time, then use that time. */
|
|
rto_delta_us = advancing_rto ?
|
|
jiffies_to_usecs(inet_csk(sk)->icsk_rto) :
|
|
tcp_rto_delta_us(sk); /* How far in future is RTO? */
|
|
if (rto_delta_us > 0)
|
|
timeout = min_t(u32, timeout, usecs_to_jiffies(rto_delta_us));
|
|
|
|
tcp_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, TCP_RTO_MAX);
|
|
return true;
|
|
}
|
|
|
|
/* Thanks to skb fast clones, we can detect if a prior transmit of
|
|
* a packet is still in a qdisc or driver queue.
|
|
* In this case, there is very little point doing a retransmit !
|
|
*/
|
|
static bool skb_still_in_host_queue(struct sock *sk,
|
|
const struct sk_buff *skb)
|
|
{
|
|
if (unlikely(skb_fclone_busy(sk, skb))) {
|
|
set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags);
|
|
smp_mb__after_atomic();
|
|
if (skb_fclone_busy(sk, skb)) {
|
|
NET_INC_STATS(sock_net(sk),
|
|
LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES);
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/* When probe timeout (PTO) fires, try send a new segment if possible, else
|
|
* retransmit the last segment.
|
|
*/
|
|
void tcp_send_loss_probe(struct sock *sk)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct sk_buff *skb;
|
|
int pcount;
|
|
int mss = tcp_current_mss(sk);
|
|
|
|
/* At most one outstanding TLP */
|
|
if (tp->tlp_high_seq)
|
|
goto rearm_timer;
|
|
|
|
tp->tlp_retrans = 0;
|
|
skb = tcp_send_head(sk);
|
|
if (skb && tcp_snd_wnd_test(tp, skb, mss)) {
|
|
pcount = tp->packets_out;
|
|
tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC);
|
|
if (tp->packets_out > pcount)
|
|
goto probe_sent;
|
|
goto rearm_timer;
|
|
}
|
|
skb = skb_rb_last(&sk->tcp_rtx_queue);
|
|
if (unlikely(!skb)) {
|
|
WARN_ONCE(tp->packets_out,
|
|
"invalid inflight: %u state %u cwnd %u mss %d\n",
|
|
tp->packets_out, sk->sk_state, tp->snd_cwnd, mss);
|
|
inet_csk(sk)->icsk_pending = 0;
|
|
return;
|
|
}
|
|
|
|
if (skb_still_in_host_queue(sk, skb))
|
|
goto rearm_timer;
|
|
|
|
pcount = tcp_skb_pcount(skb);
|
|
if (WARN_ON(!pcount))
|
|
goto rearm_timer;
|
|
|
|
if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) {
|
|
if (unlikely(tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb,
|
|
(pcount - 1) * mss, mss,
|
|
GFP_ATOMIC)))
|
|
goto rearm_timer;
|
|
skb = skb_rb_next(skb);
|
|
}
|
|
|
|
if (WARN_ON(!skb || !tcp_skb_pcount(skb)))
|
|
goto rearm_timer;
|
|
|
|
if (__tcp_retransmit_skb(sk, skb, 1))
|
|
goto rearm_timer;
|
|
|
|
tp->tlp_retrans = 1;
|
|
|
|
probe_sent:
|
|
/* Record snd_nxt for loss detection. */
|
|
tp->tlp_high_seq = tp->snd_nxt;
|
|
|
|
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSSPROBES);
|
|
/* Reset s.t. tcp_rearm_rto will restart timer from now */
|
|
inet_csk(sk)->icsk_pending = 0;
|
|
rearm_timer:
|
|
tcp_rearm_rto(sk);
|
|
}
|
|
|
|
/* Push out any pending frames which were held back due to
|
|
* TCP_CORK or attempt at coalescing tiny packets.
|
|
* The socket must be locked by the caller.
|
|
*/
|
|
void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
|
|
int nonagle)
|
|
{
|
|
/* If we are closed, the bytes will have to remain here.
|
|
* In time closedown will finish, we empty the write queue and
|
|
* all will be happy.
|
|
*/
|
|
if (unlikely(sk->sk_state == TCP_CLOSE))
|
|
return;
|
|
|
|
if (tcp_write_xmit(sk, cur_mss, nonagle, 0,
|
|
sk_gfp_mask(sk, GFP_ATOMIC)))
|
|
tcp_check_probe_timer(sk);
|
|
}
|
|
|
|
/* Send _single_ skb sitting at the send head. This function requires
|
|
* true push pending frames to setup probe timer etc.
|
|
*/
|
|
void tcp_push_one(struct sock *sk, unsigned int mss_now)
|
|
{
|
|
struct sk_buff *skb = tcp_send_head(sk);
|
|
|
|
BUG_ON(!skb || skb->len < mss_now);
|
|
|
|
tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation);
|
|
}
|
|
|
|
/* This function returns the amount that we can raise the
|
|
* usable window based on the following constraints
|
|
*
|
|
* 1. The window can never be shrunk once it is offered (RFC 793)
|
|
* 2. We limit memory per socket
|
|
*
|
|
* RFC 1122:
|
|
* "the suggested [SWS] avoidance algorithm for the receiver is to keep
|
|
* RECV.NEXT + RCV.WIN fixed until:
|
|
* RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)"
|
|
*
|
|
* i.e. don't raise the right edge of the window until you can raise
|
|
* it at least MSS bytes.
|
|
*
|
|
* Unfortunately, the recommended algorithm breaks header prediction,
|
|
* since header prediction assumes th->window stays fixed.
|
|
*
|
|
* Strictly speaking, keeping th->window fixed violates the receiver
|
|
* side SWS prevention criteria. The problem is that under this rule
|
|
* a stream of single byte packets will cause the right side of the
|
|
* window to always advance by a single byte.
|
|
*
|
|
* Of course, if the sender implements sender side SWS prevention
|
|
* then this will not be a problem.
|
|
*
|
|
* BSD seems to make the following compromise:
|
|
*
|
|
* If the free space is less than the 1/4 of the maximum
|
|
* space available and the free space is less than 1/2 mss,
|
|
* then set the window to 0.
|
|
* [ Actually, bsd uses MSS and 1/4 of maximal _window_ ]
|
|
* Otherwise, just prevent the window from shrinking
|
|
* and from being larger than the largest representable value.
|
|
*
|
|
* This prevents incremental opening of the window in the regime
|
|
* where TCP is limited by the speed of the reader side taking
|
|
* data out of the TCP receive queue. It does nothing about
|
|
* those cases where the window is constrained on the sender side
|
|
* because the pipeline is full.
|
|
*
|
|
* BSD also seems to "accidentally" limit itself to windows that are a
|
|
* multiple of MSS, at least until the free space gets quite small.
|
|
* This would appear to be a side effect of the mbuf implementation.
|
|
* Combining these two algorithms results in the observed behavior
|
|
* of having a fixed window size at almost all times.
|
|
*
|
|
* Below we obtain similar behavior by forcing the offered window to
|
|
* a multiple of the mss when it is feasible to do so.
|
|
*
|
|
* Note, we don't "adjust" for TIMESTAMP or SACK option bytes.
|
|
* Regular options like TIMESTAMP are taken into account.
|
|
*/
|
|
u32 __tcp_select_window(struct sock *sk)
|
|
{
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
/* MSS for the peer's data. Previous versions used mss_clamp
|
|
* here. I don't know if the value based on our guesses
|
|
* of peer's MSS is better for the performance. It's more correct
|
|
* but may be worse for the performance because of rcv_mss
|
|
* fluctuations. --SAW 1998/11/1
|
|
*/
|
|
int mss = icsk->icsk_ack.rcv_mss;
|
|
int free_space = tcp_space(sk);
|
|
int allowed_space = tcp_full_space(sk);
|
|
int full_space, window;
|
|
|
|
if (sk_is_mptcp(sk))
|
|
mptcp_space(sk, &free_space, &allowed_space);
|
|
|
|
full_space = min_t(int, tp->window_clamp, allowed_space);
|
|
|
|
if (unlikely(mss > full_space)) {
|
|
mss = full_space;
|
|
if (mss <= 0)
|
|
return 0;
|
|
}
|
|
if (free_space < (full_space >> 1)) {
|
|
icsk->icsk_ack.quick = 0;
|
|
|
|
if (tcp_under_memory_pressure(sk))
|
|
tp->rcv_ssthresh = min(tp->rcv_ssthresh,
|
|
4U * tp->advmss);
|
|
|
|
/* free_space might become our new window, make sure we don't
|
|
* increase it due to wscale.
|
|
*/
|
|
free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale);
|
|
|
|
/* if free space is less than mss estimate, or is below 1/16th
|
|
* of the maximum allowed, try to move to zero-window, else
|
|
* tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and
|
|
* new incoming data is dropped due to memory limits.
|
|
* With large window, mss test triggers way too late in order
|
|
* to announce zero window in time before rmem limit kicks in.
|
|
*/
|
|
if (free_space < (allowed_space >> 4) || free_space < mss)
|
|
return 0;
|
|
}
|
|
|
|
if (free_space > tp->rcv_ssthresh)
|
|
free_space = tp->rcv_ssthresh;
|
|
|
|
/* Don't do rounding if we are using window scaling, since the
|
|
* scaled window will not line up with the MSS boundary anyway.
|
|
*/
|
|
if (tp->rx_opt.rcv_wscale) {
|
|
window = free_space;
|
|
|
|
/* Advertise enough space so that it won't get scaled away.
|
|
* Import case: prevent zero window announcement if
|
|
* 1<<rcv_wscale > mss.
|
|
*/
|
|
window = ALIGN(window, (1 << tp->rx_opt.rcv_wscale));
|
|
} else {
|
|
window = tp->rcv_wnd;
|
|
/* Get the largest window that is a nice multiple of mss.
|
|
* Window clamp already applied above.
|
|
* If our current window offering is within 1 mss of the
|
|
* free space we just keep it. This prevents the divide
|
|
* and multiply from happening most of the time.
|
|
* We also don't do any window rounding when the free space
|
|
* is too small.
|
|
*/
|
|
if (window <= free_space - mss || window > free_space)
|
|
window = rounddown(free_space, mss);
|
|
else if (mss == full_space &&
|
|
free_space > window + (full_space >> 1))
|
|
window = free_space;
|
|
}
|
|
|
|
return window;
|
|
}
|
|
|
|
void tcp_skb_collapse_tstamp(struct sk_buff *skb,
|
|
const struct sk_buff *next_skb)
|
|
{
|
|
if (unlikely(tcp_has_tx_tstamp(next_skb))) {
|
|
const struct skb_shared_info *next_shinfo =
|
|
skb_shinfo(next_skb);
|
|
struct skb_shared_info *shinfo = skb_shinfo(skb);
|
|
|
|
shinfo->tx_flags |= next_shinfo->tx_flags & SKBTX_ANY_TSTAMP;
|
|
shinfo->tskey = next_shinfo->tskey;
|
|
TCP_SKB_CB(skb)->txstamp_ack |=
|
|
TCP_SKB_CB(next_skb)->txstamp_ack;
|
|
}
|
|
}
|
|
|
|
/* Collapses two adjacent SKB's during retransmission. */
|
|
static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct sk_buff *next_skb = skb_rb_next(skb);
|
|
int next_skb_size;
|
|
|
|
next_skb_size = next_skb->len;
|
|
|
|
BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1);
|
|
|
|
if (next_skb_size) {
|
|
if (next_skb_size <= skb_availroom(skb))
|
|
skb_copy_bits(next_skb, 0, skb_put(skb, next_skb_size),
|
|
next_skb_size);
|
|
else if (!tcp_skb_shift(skb, next_skb, 1, next_skb_size))
|
|
return false;
|
|
}
|
|
tcp_highest_sack_replace(sk, next_skb, skb);
|
|
|
|
/* Update sequence range on original skb. */
|
|
TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq;
|
|
|
|
/* Merge over control information. This moves PSH/FIN etc. over */
|
|
TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags;
|
|
|
|
/* All done, get rid of second SKB and account for it so
|
|
* packet counting does not break.
|
|
*/
|
|
TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS;
|
|
TCP_SKB_CB(skb)->eor = TCP_SKB_CB(next_skb)->eor;
|
|
|
|
/* changed transmit queue under us so clear hints */
|
|
tcp_clear_retrans_hints_partial(tp);
|
|
if (next_skb == tp->retransmit_skb_hint)
|
|
tp->retransmit_skb_hint = skb;
|
|
|
|
tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb));
|
|
|
|
tcp_skb_collapse_tstamp(skb, next_skb);
|
|
|
|
tcp_rtx_queue_unlink_and_free(next_skb, sk);
|
|
return true;
|
|
}
|
|
|
|
/* Check if coalescing SKBs is legal. */
|
|
static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb)
|
|
{
|
|
if (tcp_skb_pcount(skb) > 1)
|
|
return false;
|
|
if (skb_cloned(skb))
|
|
return false;
|
|
/* Some heuristics for collapsing over SACK'd could be invented */
|
|
if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/* Collapse packets in the retransmit queue to make to create
|
|
* less packets on the wire. This is only done on retransmission.
|
|
*/
|
|
static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to,
|
|
int space)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct sk_buff *skb = to, *tmp;
|
|
bool first = true;
|
|
|
|
if (!sock_net(sk)->ipv4.sysctl_tcp_retrans_collapse)
|
|
return;
|
|
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)
|
|
return;
|
|
|
|
skb_rbtree_walk_from_safe(skb, tmp) {
|
|
if (!tcp_can_collapse(sk, skb))
|
|
break;
|
|
|
|
if (!tcp_skb_can_collapse(to, skb))
|
|
break;
|
|
|
|
space -= skb->len;
|
|
|
|
if (first) {
|
|
first = false;
|
|
continue;
|
|
}
|
|
|
|
if (space < 0)
|
|
break;
|
|
|
|
if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp)))
|
|
break;
|
|
|
|
if (!tcp_collapse_retrans(sk, to))
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* This retransmits one SKB. Policy decisions and retransmit queue
|
|
* state updates are done by the caller. Returns non-zero if an
|
|
* error occurred which prevented the send.
|
|
*/
|
|
int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
|
|
{
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
unsigned int cur_mss;
|
|
int diff, len, err;
|
|
|
|
|
|
/* Inconclusive MTU probe */
|
|
if (icsk->icsk_mtup.probe_size)
|
|
icsk->icsk_mtup.probe_size = 0;
|
|
|
|
if (skb_still_in_host_queue(sk, skb))
|
|
return -EBUSY;
|
|
|
|
if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) {
|
|
if (unlikely(before(TCP_SKB_CB(skb)->end_seq, tp->snd_una))) {
|
|
WARN_ON_ONCE(1);
|
|
return -EINVAL;
|
|
}
|
|
if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq))
|
|
return -ENOMEM;
|
|
}
|
|
|
|
if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk))
|
|
return -EHOSTUNREACH; /* Routing failure or similar. */
|
|
|
|
cur_mss = tcp_current_mss(sk);
|
|
|
|
/* If receiver has shrunk his window, and skb is out of
|
|
* new window, do not retransmit it. The exception is the
|
|
* case, when window is shrunk to zero. In this case
|
|
* our retransmit serves as a zero window probe.
|
|
*/
|
|
if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) &&
|
|
TCP_SKB_CB(skb)->seq != tp->snd_una)
|
|
return -EAGAIN;
|
|
|
|
len = cur_mss * segs;
|
|
if (skb->len > len) {
|
|
if (tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, len,
|
|
cur_mss, GFP_ATOMIC))
|
|
return -ENOMEM; /* We'll try again later. */
|
|
} else {
|
|
if (skb_unclone(skb, GFP_ATOMIC))
|
|
return -ENOMEM;
|
|
|
|
diff = tcp_skb_pcount(skb);
|
|
tcp_set_skb_tso_segs(skb, cur_mss);
|
|
diff -= tcp_skb_pcount(skb);
|
|
if (diff)
|
|
tcp_adjust_pcount(sk, skb, diff);
|
|
if (skb->len < cur_mss)
|
|
tcp_retrans_try_collapse(sk, skb, cur_mss);
|
|
}
|
|
|
|
/* RFC3168, section 6.1.1.1. ECN fallback */
|
|
if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN_ECN) == TCPHDR_SYN_ECN)
|
|
tcp_ecn_clear_syn(sk, skb);
|
|
|
|
/* Update global and local TCP statistics. */
|
|
segs = tcp_skb_pcount(skb);
|
|
TCP_ADD_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS, segs);
|
|
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)
|
|
__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS);
|
|
tp->total_retrans += segs;
|
|
tp->bytes_retrans += skb->len;
|
|
|
|
/* make sure skb->data is aligned on arches that require it
|
|
* and check if ack-trimming & collapsing extended the headroom
|
|
* beyond what csum_start can cover.
|
|
*/
|
|
if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) ||
|
|
skb_headroom(skb) >= 0xFFFF)) {
|
|
struct sk_buff *nskb;
|
|
|
|
tcp_skb_tsorted_save(skb) {
|
|
nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC);
|
|
if (nskb) {
|
|
nskb->dev = NULL;
|
|
err = tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC);
|
|
} else {
|
|
err = -ENOBUFS;
|
|
}
|
|
} tcp_skb_tsorted_restore(skb);
|
|
|
|
if (!err) {
|
|
tcp_update_skb_after_send(sk, skb, tp->tcp_wstamp_ns);
|
|
tcp_rate_skb_sent(sk, skb);
|
|
}
|
|
} else {
|
|
err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC);
|
|
}
|
|
|
|
/* To avoid taking spuriously low RTT samples based on a timestamp
|
|
* for a transmit that never happened, always mark EVER_RETRANS
|
|
*/
|
|
TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS;
|
|
|
|
if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RETRANS_CB_FLAG))
|
|
tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RETRANS_CB,
|
|
TCP_SKB_CB(skb)->seq, segs, err);
|
|
|
|
if (likely(!err)) {
|
|
trace_tcp_retransmit_skb(sk, skb);
|
|
} else if (err != -EBUSY) {
|
|
NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL, segs);
|
|
}
|
|
return err;
|
|
}
|
|
|
|
int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
int err = __tcp_retransmit_skb(sk, skb, segs);
|
|
|
|
if (err == 0) {
|
|
#if FASTRETRANS_DEBUG > 0
|
|
if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) {
|
|
net_dbg_ratelimited("retrans_out leaked\n");
|
|
}
|
|
#endif
|
|
TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS;
|
|
tp->retrans_out += tcp_skb_pcount(skb);
|
|
}
|
|
|
|
/* Save stamp of the first (attempted) retransmit. */
|
|
if (!tp->retrans_stamp)
|
|
tp->retrans_stamp = tcp_skb_timestamp(skb);
|
|
|
|
if (tp->undo_retrans < 0)
|
|
tp->undo_retrans = 0;
|
|
tp->undo_retrans += tcp_skb_pcount(skb);
|
|
return err;
|
|
}
|
|
|
|
/* This gets called after a retransmit timeout, and the initially
|
|
* retransmitted data is acknowledged. It tries to continue
|
|
* resending the rest of the retransmit queue, until either
|
|
* we've sent it all or the congestion window limit is reached.
|
|
*/
|
|
void tcp_xmit_retransmit_queue(struct sock *sk)
|
|
{
|
|
const struct inet_connection_sock *icsk = inet_csk(sk);
|
|
struct sk_buff *skb, *rtx_head, *hole = NULL;
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
bool rearm_timer = false;
|
|
u32 max_segs;
|
|
int mib_idx;
|
|
|
|
if (!tp->packets_out)
|
|
return;
|
|
|
|
rtx_head = tcp_rtx_queue_head(sk);
|
|
skb = tp->retransmit_skb_hint ?: rtx_head;
|
|
max_segs = tcp_tso_segs(sk, tcp_current_mss(sk));
|
|
skb_rbtree_walk_from(skb) {
|
|
__u8 sacked;
|
|
int segs;
|
|
|
|
if (tcp_pacing_check(sk))
|
|
break;
|
|
|
|
/* we could do better than to assign each time */
|
|
if (!hole)
|
|
tp->retransmit_skb_hint = skb;
|
|
|
|
segs = tp->snd_cwnd - tcp_packets_in_flight(tp);
|
|
if (segs <= 0)
|
|
break;
|
|
sacked = TCP_SKB_CB(skb)->sacked;
|
|
/* In case tcp_shift_skb_data() have aggregated large skbs,
|
|
* we need to make sure not sending too bigs TSO packets
|
|
*/
|
|
segs = min_t(int, segs, max_segs);
|
|
|
|
if (tp->retrans_out >= tp->lost_out) {
|
|
break;
|
|
} else if (!(sacked & TCPCB_LOST)) {
|
|
if (!hole && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED)))
|
|
hole = skb;
|
|
continue;
|
|
|
|
} else {
|
|
if (icsk->icsk_ca_state != TCP_CA_Loss)
|
|
mib_idx = LINUX_MIB_TCPFASTRETRANS;
|
|
else
|
|
mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS;
|
|
}
|
|
|
|
if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS))
|
|
continue;
|
|
|
|
if (tcp_small_queue_check(sk, skb, 1))
|
|
break;
|
|
|
|
if (tcp_retransmit_skb(sk, skb, segs))
|
|
break;
|
|
|
|
NET_ADD_STATS(sock_net(sk), mib_idx, tcp_skb_pcount(skb));
|
|
|
|
if (tcp_in_cwnd_reduction(sk))
|
|
tp->prr_out += tcp_skb_pcount(skb);
|
|
|
|
if (skb == rtx_head &&
|
|
icsk->icsk_pending != ICSK_TIME_REO_TIMEOUT)
|
|
rearm_timer = true;
|
|
|
|
}
|
|
if (rearm_timer)
|
|
tcp_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
|
|
inet_csk(sk)->icsk_rto,
|
|
TCP_RTO_MAX);
|
|
}
|
|
|
|
/* We allow to exceed memory limits for FIN packets to expedite
|
|
* connection tear down and (memory) recovery.
|
|
* Otherwise tcp_send_fin() could be tempted to either delay FIN
|
|
* or even be forced to close flow without any FIN.
|
|
* In general, we want to allow one skb per socket to avoid hangs
|
|
* with edge trigger epoll()
|
|
*/
|
|
void sk_forced_mem_schedule(struct sock *sk, int size)
|
|
{
|
|
int amt;
|
|
|
|
if (size <= sk->sk_forward_alloc)
|
|
return;
|
|
amt = sk_mem_pages(size);
|
|
sk->sk_forward_alloc += amt * SK_MEM_QUANTUM;
|
|
sk_memory_allocated_add(sk, amt);
|
|
|
|
if (mem_cgroup_sockets_enabled && sk->sk_memcg)
|
|
mem_cgroup_charge_skmem(sk->sk_memcg, amt,
|
|
gfp_memcg_charge() | __GFP_NOFAIL);
|
|
}
|
|
|
|
/* Send a FIN. The caller locks the socket for us.
|
|
* We should try to send a FIN packet really hard, but eventually give up.
|
|
*/
|
|
void tcp_send_fin(struct sock *sk)
|
|
{
|
|
struct sk_buff *skb, *tskb, *tail = tcp_write_queue_tail(sk);
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
|
|
/* Optimization, tack on the FIN if we have one skb in write queue and
|
|
* this skb was not yet sent, or we are under memory pressure.
|
|
* Note: in the latter case, FIN packet will be sent after a timeout,
|
|
* as TCP stack thinks it has already been transmitted.
|
|
*/
|
|
tskb = tail;
|
|
if (!tskb && tcp_under_memory_pressure(sk))
|
|
tskb = skb_rb_last(&sk->tcp_rtx_queue);
|
|
|
|
if (tskb) {
|
|
TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN;
|
|
TCP_SKB_CB(tskb)->end_seq++;
|
|
tp->write_seq++;
|
|
if (!tail) {
|
|
/* This means tskb was already sent.
|
|
* Pretend we included the FIN on previous transmit.
|
|
* We need to set tp->snd_nxt to the value it would have
|
|
* if FIN had been sent. This is because retransmit path
|
|
* does not change tp->snd_nxt.
|
|
*/
|
|
WRITE_ONCE(tp->snd_nxt, tp->snd_nxt + 1);
|
|
return;
|
|
}
|
|
} else {
|
|
skb = alloc_skb_fclone(MAX_TCP_HEADER, sk->sk_allocation);
|
|
if (unlikely(!skb))
|
|
return;
|
|
|
|
INIT_LIST_HEAD(&skb->tcp_tsorted_anchor);
|
|
skb_reserve(skb, MAX_TCP_HEADER);
|
|
sk_forced_mem_schedule(sk, skb->truesize);
|
|
/* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */
|
|
tcp_init_nondata_skb(skb, tp->write_seq,
|
|
TCPHDR_ACK | TCPHDR_FIN);
|
|
tcp_queue_skb(sk, skb);
|
|
}
|
|
__tcp_push_pending_frames(sk, tcp_current_mss(sk), TCP_NAGLE_OFF);
|
|
}
|
|
|
|
/* We get here when a process closes a file descriptor (either due to
|
|
* an explicit close() or as a byproduct of exit()'ing) and there
|
|
* was unread data in the receive queue. This behavior is recommended
|
|
* by RFC 2525, section 2.17. -DaveM
|
|
*/
|
|
void tcp_send_active_reset(struct sock *sk, gfp_t priority)
|
|
{
|
|
struct sk_buff *skb;
|
|
|
|
TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS);
|
|
|
|
/* NOTE: No TCP options attached and we never retransmit this. */
|
|
skb = alloc_skb(MAX_TCP_HEADER, priority);
|
|
if (!skb) {
|
|
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED);
|
|
return;
|
|
}
|
|
|
|
/* Reserve space for headers and prepare control bits. */
|
|
skb_reserve(skb, MAX_TCP_HEADER);
|
|
tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk),
|
|
TCPHDR_ACK | TCPHDR_RST);
|
|
tcp_mstamp_refresh(tcp_sk(sk));
|
|
/* Send it off. */
|
|
if (tcp_transmit_skb(sk, skb, 0, priority))
|
|
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED);
|
|
|
|
/* skb of trace_tcp_send_reset() keeps the skb that caused RST,
|
|
* skb here is different to the troublesome skb, so use NULL
|
|
*/
|
|
trace_tcp_send_reset(sk, NULL);
|
|
}
|
|
|
|
/* Send a crossed SYN-ACK during socket establishment.
|
|
* WARNING: This routine must only be called when we have already sent
|
|
* a SYN packet that crossed the incoming SYN that caused this routine
|
|
* to get called. If this assumption fails then the initial rcv_wnd
|
|
* and rcv_wscale values will not be correct.
|
|
*/
|
|
int tcp_send_synack(struct sock *sk)
|
|
{
|
|
struct sk_buff *skb;
|
|
|
|
skb = tcp_rtx_queue_head(sk);
|
|
if (!skb || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
|
|
pr_err("%s: wrong queue state\n", __func__);
|
|
return -EFAULT;
|
|
}
|
|
if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) {
|
|
if (skb_cloned(skb)) {
|
|
struct sk_buff *nskb;
|
|
|
|
tcp_skb_tsorted_save(skb) {
|
|
nskb = skb_copy(skb, GFP_ATOMIC);
|
|
} tcp_skb_tsorted_restore(skb);
|
|
if (!nskb)
|
|
return -ENOMEM;
|
|
INIT_LIST_HEAD(&nskb->tcp_tsorted_anchor);
|
|
tcp_highest_sack_replace(sk, skb, nskb);
|
|
tcp_rtx_queue_unlink_and_free(skb, sk);
|
|
__skb_header_release(nskb);
|
|
tcp_rbtree_insert(&sk->tcp_rtx_queue, nskb);
|
|
sk_wmem_queued_add(sk, nskb->truesize);
|
|
sk_mem_charge(sk, nskb->truesize);
|
|
skb = nskb;
|
|
}
|
|
|
|
TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK;
|
|
tcp_ecn_send_synack(sk, skb);
|
|
}
|
|
return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC);
|
|
}
|
|
|
|
/**
|
|
* tcp_make_synack - Allocate one skb and build a SYNACK packet.
|
|
* @sk: listener socket
|
|
* @dst: dst entry attached to the SYNACK. It is consumed and caller
|
|
* should not use it again.
|
|
* @req: request_sock pointer
|
|
* @foc: cookie for tcp fast open
|
|
* @synack_type: Type of synack to prepare
|
|
* @syn_skb: SYN packet just received. It could be NULL for rtx case.
|
|
*/
|
|
struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
|
|
struct request_sock *req,
|
|
struct tcp_fastopen_cookie *foc,
|
|
enum tcp_synack_type synack_type,
|
|
struct sk_buff *syn_skb)
|
|
{
|
|
struct inet_request_sock *ireq = inet_rsk(req);
|
|
const struct tcp_sock *tp = tcp_sk(sk);
|
|
struct tcp_md5sig_key *md5 = NULL;
|
|
struct tcp_out_options opts;
|
|
struct sk_buff *skb;
|
|
int tcp_header_size;
|
|
struct tcphdr *th;
|
|
int mss;
|
|
u64 now;
|
|
|
|
skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC);
|
|
if (unlikely(!skb)) {
|
|
dst_release(dst);
|
|
return NULL;
|
|
}
|
|
/* Reserve space for headers. */
|
|
skb_reserve(skb, MAX_TCP_HEADER);
|
|
|
|
switch (synack_type) {
|
|
case TCP_SYNACK_NORMAL:
|
|
skb_set_owner_w(skb, req_to_sk(req));
|
|
break;
|
|
case TCP_SYNACK_COOKIE:
|
|
/* Under synflood, we do not attach skb to a socket,
|
|
* to avoid false sharing.
|
|
*/
|
|
break;
|
|
case TCP_SYNACK_FASTOPEN:
|
|
/* sk is a const pointer, because we want to express multiple
|
|
* cpu might call us concurrently.
|
|
* sk->sk_wmem_alloc in an atomic, we can promote to rw.
|
|
*/
|
|
skb_set_owner_w(skb, (struct sock *)sk);
|
|
break;
|
|
}
|
|
skb_dst_set(skb, dst);
|
|
|
|
mss = tcp_mss_clamp(tp, dst_metric_advmss(dst));
|
|
|
|
memset(&opts, 0, sizeof(opts));
|
|
now = tcp_clock_ns();
|
|
#ifdef CONFIG_SYN_COOKIES
|
|
if (unlikely(synack_type == TCP_SYNACK_COOKIE && ireq->tstamp_ok))
|
|
skb->skb_mstamp_ns = cookie_init_timestamp(req, now);
|
|
else
|
|
#endif
|
|
{
|
|
skb->skb_mstamp_ns = now;
|
|
if (!tcp_rsk(req)->snt_synack) /* Timestamp first SYNACK */
|
|
tcp_rsk(req)->snt_synack = tcp_skb_timestamp_us(skb);
|
|
}
|
|
|
|
#ifdef CONFIG_TCP_MD5SIG
|
|
rcu_read_lock();
|
|
md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req));
|
|
#endif
|
|
skb_set_hash(skb, tcp_rsk(req)->txhash, PKT_HASH_TYPE_L4);
|
|
/* bpf program will be interested in the tcp_flags */
|
|
TCP_SKB_CB(skb)->tcp_flags = TCPHDR_SYN | TCPHDR_ACK;
|
|
tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, md5,
|
|
foc, synack_type,
|
|
syn_skb) + sizeof(*th);
|
|
|
|
skb_push(skb, tcp_header_size);
|
|
skb_reset_transport_header(skb);
|
|
|
|
th = (struct tcphdr *)skb->data;
|
|
memset(th, 0, sizeof(struct tcphdr));
|
|
th->syn = 1;
|
|
th->ack = 1;
|
|
tcp_ecn_make_synack(req, th);
|
|
th->source = htons(ireq->ir_num);
|
|
th->dest = ireq->ir_rmt_port;
|
|
skb->mark = ireq->ir_mark;
|
|
skb->ip_summed = CHECKSUM_PARTIAL;
|
|
th->seq = htonl(tcp_rsk(req)->snt_isn);
|
|
/* XXX data is queued and acked as is. No buffer/window check */
|
|
th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt);
|
|
|
|
/* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */
|
|
th->window = htons(min(req->rsk_rcv_wnd, 65535U));
|
|
tcp_options_write((__be32 *)(th + 1), NULL, &opts);
|
|
th->doff = (tcp_header_size >> 2);
|
|
__TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS);
|
|
|
|
#ifdef CONFIG_TCP_MD5SIG
|
|
/* Okay, we have all we need - do the md5 hash if needed */
|
|
if (md5)
|
|
tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location,
|
|
md5, req_to_sk(req), skb);
|
|
rcu_read_unlock();
|
|
#endif
|
|
|
|
bpf_skops_write_hdr_opt((struct sock *)sk, skb, req, syn_skb,
|
|
synack_type, &opts);
|
|
|
|
skb->skb_mstamp_ns = now;
|
|
tcp_add_tx_delay(skb, tp);
|
|
|
|
return skb;
|
|
}
|
|
EXPORT_SYMBOL(tcp_make_synack);
|
|
|
|
static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst)
|
|
{
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
const struct tcp_congestion_ops *ca;
|
|
u32 ca_key = dst_metric(dst, RTAX_CC_ALGO);
|
|
|
|
if (ca_key == TCP_CA_UNSPEC)
|
|
return;
|
|
|
|
rcu_read_lock();
|
|
ca = tcp_ca_find_key(ca_key);
|
|
if (likely(ca && bpf_try_module_get(ca, ca->owner))) {
|
|
bpf_module_put(icsk->icsk_ca_ops, icsk->icsk_ca_ops->owner);
|
|
icsk->icsk_ca_dst_locked = tcp_ca_dst_locked(dst);
|
|
icsk->icsk_ca_ops = ca;
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/* Do all connect socket setups that can be done AF independent. */
|
|
static void tcp_connect_init(struct sock *sk)
|
|
{
|
|
const struct dst_entry *dst = __sk_dst_get(sk);
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
__u8 rcv_wscale;
|
|
u32 rcv_wnd;
|
|
|
|
/* We'll fix this up when we get a response from the other end.
|
|
* See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT.
|
|
*/
|
|
tp->tcp_header_len = sizeof(struct tcphdr);
|
|
if (sock_net(sk)->ipv4.sysctl_tcp_timestamps)
|
|
tp->tcp_header_len += TCPOLEN_TSTAMP_ALIGNED;
|
|
|
|
#ifdef CONFIG_TCP_MD5SIG
|
|
if (tp->af_specific->md5_lookup(sk, sk))
|
|
tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED;
|
|
#endif
|
|
|
|
/* If user gave his TCP_MAXSEG, record it to clamp */
|
|
if (tp->rx_opt.user_mss)
|
|
tp->rx_opt.mss_clamp = tp->rx_opt.user_mss;
|
|
tp->max_window = 0;
|
|
tcp_mtup_init(sk);
|
|
tcp_sync_mss(sk, dst_mtu(dst));
|
|
|
|
tcp_ca_dst_init(sk, dst);
|
|
|
|
if (!tp->window_clamp)
|
|
tp->window_clamp = dst_metric(dst, RTAX_WINDOW);
|
|
tp->advmss = tcp_mss_clamp(tp, dst_metric_advmss(dst));
|
|
|
|
tcp_initialize_rcv_mss(sk);
|
|
|
|
/* limit the window selection if the user enforce a smaller rx buffer */
|
|
if (sk->sk_userlocks & SOCK_RCVBUF_LOCK &&
|
|
(tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0))
|
|
tp->window_clamp = tcp_full_space(sk);
|
|
|
|
rcv_wnd = tcp_rwnd_init_bpf(sk);
|
|
if (rcv_wnd == 0)
|
|
rcv_wnd = dst_metric(dst, RTAX_INITRWND);
|
|
|
|
tcp_select_initial_window(sk, tcp_full_space(sk),
|
|
tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0),
|
|
&tp->rcv_wnd,
|
|
&tp->window_clamp,
|
|
sock_net(sk)->ipv4.sysctl_tcp_window_scaling,
|
|
&rcv_wscale,
|
|
rcv_wnd);
|
|
|
|
tp->rx_opt.rcv_wscale = rcv_wscale;
|
|
tp->rcv_ssthresh = tp->rcv_wnd;
|
|
|
|
sk->sk_err = 0;
|
|
sock_reset_flag(sk, SOCK_DONE);
|
|
tp->snd_wnd = 0;
|
|
tcp_init_wl(tp, 0);
|
|
tcp_write_queue_purge(sk);
|
|
tp->snd_una = tp->write_seq;
|
|
tp->snd_sml = tp->write_seq;
|
|
tp->snd_up = tp->write_seq;
|
|
WRITE_ONCE(tp->snd_nxt, tp->write_seq);
|
|
|
|
if (likely(!tp->repair))
|
|
tp->rcv_nxt = 0;
|
|
else
|
|
tp->rcv_tstamp = tcp_jiffies32;
|
|
tp->rcv_wup = tp->rcv_nxt;
|
|
WRITE_ONCE(tp->copied_seq, tp->rcv_nxt);
|
|
|
|
inet_csk(sk)->icsk_rto = tcp_timeout_init(sk);
|
|
inet_csk(sk)->icsk_retransmits = 0;
|
|
tcp_clear_retrans(tp);
|
|
}
|
|
|
|
static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
|
|
|
|
tcb->end_seq += skb->len;
|
|
__skb_header_release(skb);
|
|
sk_wmem_queued_add(sk, skb->truesize);
|
|
sk_mem_charge(sk, skb->truesize);
|
|
WRITE_ONCE(tp->write_seq, tcb->end_seq);
|
|
tp->packets_out += tcp_skb_pcount(skb);
|
|
}
|
|
|
|
/* Build and send a SYN with data and (cached) Fast Open cookie. However,
|
|
* queue a data-only packet after the regular SYN, such that regular SYNs
|
|
* are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges
|
|
* only the SYN sequence, the data are retransmitted in the first ACK.
|
|
* If cookie is not cached or other error occurs, falls back to send a
|
|
* regular SYN with Fast Open cookie request option.
|
|
*/
|
|
static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct tcp_fastopen_request *fo = tp->fastopen_req;
|
|
int space, err = 0;
|
|
struct sk_buff *syn_data;
|
|
|
|
tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */
|
|
if (!tcp_fastopen_cookie_check(sk, &tp->rx_opt.mss_clamp, &fo->cookie))
|
|
goto fallback;
|
|
|
|
/* MSS for SYN-data is based on cached MSS and bounded by PMTU and
|
|
* user-MSS. Reserve maximum option space for middleboxes that add
|
|
* private TCP options. The cost is reduced data space in SYN :(
|
|
*/
|
|
tp->rx_opt.mss_clamp = tcp_mss_clamp(tp, tp->rx_opt.mss_clamp);
|
|
|
|
space = __tcp_mtu_to_mss(sk, inet_csk(sk)->icsk_pmtu_cookie) -
|
|
MAX_TCP_OPTION_SPACE;
|
|
|
|
space = min_t(size_t, space, fo->size);
|
|
|
|
/* limit to order-0 allocations */
|
|
space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER));
|
|
|
|
syn_data = sk_stream_alloc_skb(sk, space, sk->sk_allocation, false);
|
|
if (!syn_data)
|
|
goto fallback;
|
|
syn_data->ip_summed = CHECKSUM_PARTIAL;
|
|
memcpy(syn_data->cb, syn->cb, sizeof(syn->cb));
|
|
if (space) {
|
|
int copied = copy_from_iter(skb_put(syn_data, space), space,
|
|
&fo->data->msg_iter);
|
|
if (unlikely(!copied)) {
|
|
tcp_skb_tsorted_anchor_cleanup(syn_data);
|
|
kfree_skb(syn_data);
|
|
goto fallback;
|
|
}
|
|
if (copied != space) {
|
|
skb_trim(syn_data, copied);
|
|
space = copied;
|
|
}
|
|
skb_zcopy_set(syn_data, fo->uarg, NULL);
|
|
}
|
|
/* No more data pending in inet_wait_for_connect() */
|
|
if (space == fo->size)
|
|
fo->data = NULL;
|
|
fo->copied = space;
|
|
|
|
tcp_connect_queue_skb(sk, syn_data);
|
|
if (syn_data->len)
|
|
tcp_chrono_start(sk, TCP_CHRONO_BUSY);
|
|
|
|
err = tcp_transmit_skb(sk, syn_data, 1, sk->sk_allocation);
|
|
|
|
syn->skb_mstamp_ns = syn_data->skb_mstamp_ns;
|
|
|
|
/* Now full SYN+DATA was cloned and sent (or not),
|
|
* remove the SYN from the original skb (syn_data)
|
|
* we keep in write queue in case of a retransmit, as we
|
|
* also have the SYN packet (with no data) in the same queue.
|
|
*/
|
|
TCP_SKB_CB(syn_data)->seq++;
|
|
TCP_SKB_CB(syn_data)->tcp_flags = TCPHDR_ACK | TCPHDR_PSH;
|
|
if (!err) {
|
|
tp->syn_data = (fo->copied > 0);
|
|
tcp_rbtree_insert(&sk->tcp_rtx_queue, syn_data);
|
|
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT);
|
|
goto done;
|
|
}
|
|
|
|
/* data was not sent, put it in write_queue */
|
|
__skb_queue_tail(&sk->sk_write_queue, syn_data);
|
|
tp->packets_out -= tcp_skb_pcount(syn_data);
|
|
|
|
fallback:
|
|
/* Send a regular SYN with Fast Open cookie request option */
|
|
if (fo->cookie.len > 0)
|
|
fo->cookie.len = 0;
|
|
err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation);
|
|
if (err)
|
|
tp->syn_fastopen = 0;
|
|
done:
|
|
fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */
|
|
return err;
|
|
}
|
|
|
|
/* Build a SYN and send it off. */
|
|
int tcp_connect(struct sock *sk)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct sk_buff *buff;
|
|
int err;
|
|
|
|
tcp_call_bpf(sk, BPF_SOCK_OPS_TCP_CONNECT_CB, 0, NULL);
|
|
|
|
if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk))
|
|
return -EHOSTUNREACH; /* Routing failure or similar. */
|
|
|
|
tcp_connect_init(sk);
|
|
|
|
if (unlikely(tp->repair)) {
|
|
tcp_finish_connect(sk, NULL);
|
|
return 0;
|
|
}
|
|
|
|
buff = sk_stream_alloc_skb(sk, 0, sk->sk_allocation, true);
|
|
if (unlikely(!buff))
|
|
return -ENOBUFS;
|
|
|
|
tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN);
|
|
tcp_mstamp_refresh(tp);
|
|
tp->retrans_stamp = tcp_time_stamp(tp);
|
|
tcp_connect_queue_skb(sk, buff);
|
|
tcp_ecn_send_syn(sk, buff);
|
|
tcp_rbtree_insert(&sk->tcp_rtx_queue, buff);
|
|
|
|
/* Send off SYN; include data in Fast Open. */
|
|
err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) :
|
|
tcp_transmit_skb(sk, buff, 1, sk->sk_allocation);
|
|
if (err == -ECONNREFUSED)
|
|
return err;
|
|
|
|
/* We change tp->snd_nxt after the tcp_transmit_skb() call
|
|
* in order to make this packet get counted in tcpOutSegs.
|
|
*/
|
|
WRITE_ONCE(tp->snd_nxt, tp->write_seq);
|
|
tp->pushed_seq = tp->write_seq;
|
|
buff = tcp_send_head(sk);
|
|
if (unlikely(buff)) {
|
|
WRITE_ONCE(tp->snd_nxt, TCP_SKB_CB(buff)->seq);
|
|
tp->pushed_seq = TCP_SKB_CB(buff)->seq;
|
|
}
|
|
TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS);
|
|
|
|
/* Timer for repeating the SYN until an answer. */
|
|
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
|
|
inet_csk(sk)->icsk_rto, TCP_RTO_MAX);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(tcp_connect);
|
|
|
|
/* Send out a delayed ack, the caller does the policy checking
|
|
* to see if we should even be here. See tcp_input.c:tcp_ack_snd_check()
|
|
* for details.
|
|
*/
|
|
void tcp_send_delayed_ack(struct sock *sk)
|
|
{
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
int ato = icsk->icsk_ack.ato;
|
|
unsigned long timeout;
|
|
|
|
if (ato > TCP_DELACK_MIN) {
|
|
const struct tcp_sock *tp = tcp_sk(sk);
|
|
int max_ato = HZ / 2;
|
|
|
|
if (inet_csk_in_pingpong_mode(sk) ||
|
|
(icsk->icsk_ack.pending & ICSK_ACK_PUSHED))
|
|
max_ato = TCP_DELACK_MAX;
|
|
|
|
/* Slow path, intersegment interval is "high". */
|
|
|
|
/* If some rtt estimate is known, use it to bound delayed ack.
|
|
* Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements
|
|
* directly.
|
|
*/
|
|
if (tp->srtt_us) {
|
|
int rtt = max_t(int, usecs_to_jiffies(tp->srtt_us >> 3),
|
|
TCP_DELACK_MIN);
|
|
|
|
if (rtt < max_ato)
|
|
max_ato = rtt;
|
|
}
|
|
|
|
ato = min(ato, max_ato);
|
|
}
|
|
|
|
ato = min_t(u32, ato, inet_csk(sk)->icsk_delack_max);
|
|
|
|
/* Stay within the limit we were given */
|
|
timeout = jiffies + ato;
|
|
|
|
/* Use new timeout only if there wasn't a older one earlier. */
|
|
if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
|
|
/* If delack timer is about to expire, send ACK now. */
|
|
if (time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) {
|
|
tcp_send_ack(sk);
|
|
return;
|
|
}
|
|
|
|
if (!time_before(timeout, icsk->icsk_ack.timeout))
|
|
timeout = icsk->icsk_ack.timeout;
|
|
}
|
|
icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
|
|
icsk->icsk_ack.timeout = timeout;
|
|
sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
|
|
}
|
|
|
|
/* This routine sends an ack and also updates the window. */
|
|
void __tcp_send_ack(struct sock *sk, u32 rcv_nxt)
|
|
{
|
|
struct sk_buff *buff;
|
|
|
|
/* If we have been reset, we may not send again. */
|
|
if (sk->sk_state == TCP_CLOSE)
|
|
return;
|
|
|
|
/* We are not putting this on the write queue, so
|
|
* tcp_transmit_skb() will set the ownership to this
|
|
* sock.
|
|
*/
|
|
buff = alloc_skb(MAX_TCP_HEADER,
|
|
sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN));
|
|
if (unlikely(!buff)) {
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
unsigned long delay;
|
|
|
|
delay = TCP_DELACK_MAX << icsk->icsk_ack.retry;
|
|
if (delay < TCP_RTO_MAX)
|
|
icsk->icsk_ack.retry++;
|
|
inet_csk_schedule_ack(sk);
|
|
icsk->icsk_ack.ato = TCP_ATO_MIN;
|
|
inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, delay, TCP_RTO_MAX);
|
|
return;
|
|
}
|
|
|
|
/* Reserve space for headers and prepare control bits. */
|
|
skb_reserve(buff, MAX_TCP_HEADER);
|
|
tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK);
|
|
|
|
/* We do not want pure acks influencing TCP Small Queues or fq/pacing
|
|
* too much.
|
|
* SKB_TRUESIZE(max(1 .. 66, MAX_TCP_HEADER)) is unfortunately ~784
|
|
*/
|
|
skb_set_tcp_pure_ack(buff);
|
|
|
|
/* Send it off, this clears delayed acks for us. */
|
|
__tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0, rcv_nxt);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__tcp_send_ack);
|
|
|
|
void tcp_send_ack(struct sock *sk)
|
|
{
|
|
__tcp_send_ack(sk, tcp_sk(sk)->rcv_nxt);
|
|
}
|
|
|
|
/* This routine sends a packet with an out of date sequence
|
|
* number. It assumes the other end will try to ack it.
|
|
*
|
|
* Question: what should we make while urgent mode?
|
|
* 4.4BSD forces sending single byte of data. We cannot send
|
|
* out of window data, because we have SND.NXT==SND.MAX...
|
|
*
|
|
* Current solution: to send TWO zero-length segments in urgent mode:
|
|
* one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is
|
|
* out-of-date with SND.UNA-1 to probe window.
|
|
*/
|
|
static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct sk_buff *skb;
|
|
|
|
/* We don't queue it, tcp_transmit_skb() sets ownership. */
|
|
skb = alloc_skb(MAX_TCP_HEADER,
|
|
sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN));
|
|
if (!skb)
|
|
return -1;
|
|
|
|
/* Reserve space for headers and set control bits. */
|
|
skb_reserve(skb, MAX_TCP_HEADER);
|
|
/* Use a previous sequence. This should cause the other
|
|
* end to send an ack. Don't queue or clone SKB, just
|
|
* send it.
|
|
*/
|
|
tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK);
|
|
NET_INC_STATS(sock_net(sk), mib);
|
|
return tcp_transmit_skb(sk, skb, 0, (__force gfp_t)0);
|
|
}
|
|
|
|
/* Called from setsockopt( ... TCP_REPAIR ) */
|
|
void tcp_send_window_probe(struct sock *sk)
|
|
{
|
|
if (sk->sk_state == TCP_ESTABLISHED) {
|
|
tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1;
|
|
tcp_mstamp_refresh(tcp_sk(sk));
|
|
tcp_xmit_probe_skb(sk, 0, LINUX_MIB_TCPWINPROBE);
|
|
}
|
|
}
|
|
|
|
/* Initiate keepalive or window probe from timer. */
|
|
int tcp_write_wakeup(struct sock *sk, int mib)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct sk_buff *skb;
|
|
|
|
if (sk->sk_state == TCP_CLOSE)
|
|
return -1;
|
|
|
|
skb = tcp_send_head(sk);
|
|
if (skb && before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) {
|
|
int err;
|
|
unsigned int mss = tcp_current_mss(sk);
|
|
unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq;
|
|
|
|
if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq))
|
|
tp->pushed_seq = TCP_SKB_CB(skb)->end_seq;
|
|
|
|
/* We are probing the opening of a window
|
|
* but the window size is != 0
|
|
* must have been a result SWS avoidance ( sender )
|
|
*/
|
|
if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq ||
|
|
skb->len > mss) {
|
|
seg_size = min(seg_size, mss);
|
|
TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH;
|
|
if (tcp_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE,
|
|
skb, seg_size, mss, GFP_ATOMIC))
|
|
return -1;
|
|
} else if (!tcp_skb_pcount(skb))
|
|
tcp_set_skb_tso_segs(skb, mss);
|
|
|
|
TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH;
|
|
err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC);
|
|
if (!err)
|
|
tcp_event_new_data_sent(sk, skb);
|
|
return err;
|
|
} else {
|
|
if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF))
|
|
tcp_xmit_probe_skb(sk, 1, mib);
|
|
return tcp_xmit_probe_skb(sk, 0, mib);
|
|
}
|
|
}
|
|
|
|
/* A window probe timeout has occurred. If window is not closed send
|
|
* a partial packet else a zero probe.
|
|
*/
|
|
void tcp_send_probe0(struct sock *sk)
|
|
{
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct net *net = sock_net(sk);
|
|
unsigned long timeout;
|
|
int err;
|
|
|
|
err = tcp_write_wakeup(sk, LINUX_MIB_TCPWINPROBE);
|
|
|
|
if (tp->packets_out || tcp_write_queue_empty(sk)) {
|
|
/* Cancel probe timer, if it is not required. */
|
|
icsk->icsk_probes_out = 0;
|
|
icsk->icsk_backoff = 0;
|
|
icsk->icsk_probes_tstamp = 0;
|
|
return;
|
|
}
|
|
|
|
icsk->icsk_probes_out++;
|
|
if (err <= 0) {
|
|
if (icsk->icsk_backoff < net->ipv4.sysctl_tcp_retries2)
|
|
icsk->icsk_backoff++;
|
|
timeout = tcp_probe0_when(sk, TCP_RTO_MAX);
|
|
} else {
|
|
/* If packet was not sent due to local congestion,
|
|
* Let senders fight for local resources conservatively.
|
|
*/
|
|
timeout = TCP_RESOURCE_PROBE_INTERVAL;
|
|
}
|
|
|
|
timeout = tcp_clamp_probe0_to_user_timeout(sk, timeout);
|
|
tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, timeout, TCP_RTO_MAX);
|
|
}
|
|
|
|
int tcp_rtx_synack(const struct sock *sk, struct request_sock *req)
|
|
{
|
|
const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific;
|
|
struct flowi fl;
|
|
int res;
|
|
|
|
tcp_rsk(req)->txhash = net_tx_rndhash();
|
|
res = af_ops->send_synack(sk, NULL, &fl, req, NULL, TCP_SYNACK_NORMAL,
|
|
NULL);
|
|
if (!res) {
|
|
__TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS);
|
|
__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS);
|
|
if (unlikely(tcp_passive_fastopen(sk)))
|
|
tcp_sk(sk)->total_retrans++;
|
|
trace_tcp_retransmit_synack(sk, req);
|
|
}
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(tcp_rtx_synack);
|