Release 4.8 net/ipv4/tcp_input.c
/*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* Implementation of the Transmission Control Protocol(TCP).
*
* Authors: Ross Biro
* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
* Mark Evans, <evansmp@uhura.aston.ac.uk>
* Corey Minyard <wf-rch!minyard@relay.EU.net>
* Florian La Roche, <flla@stud.uni-sb.de>
* Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
* Linus Torvalds, <torvalds@cs.helsinki.fi>
* Alan Cox, <gw4pts@gw4pts.ampr.org>
* Matthew Dillon, <dillon@apollo.west.oic.com>
* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
* Jorge Cwik, <jorge@laser.satlink.net>
*/
/*
* Changes:
* Pedro Roque : Fast Retransmit/Recovery.
* Two receive queues.
* Retransmit queue handled by TCP.
* Better retransmit timer handling.
* New congestion avoidance.
* Header prediction.
* Variable renaming.
*
* Eric : Fast Retransmit.
* Randy Scott : MSS option defines.
* Eric Schenk : Fixes to slow start algorithm.
* Eric Schenk : Yet another double ACK bug.
* Eric Schenk : Delayed ACK bug fixes.
* Eric Schenk : Floyd style fast retrans war avoidance.
* David S. Miller : Don't allow zero congestion window.
* Eric Schenk : Fix retransmitter so that it sends
* next packet on ack of previous packet.
* Andi Kleen : Moved open_request checking here
* and process RSTs for open_requests.
* Andi Kleen : Better prune_queue, and other fixes.
* Andrey Savochkin: Fix RTT measurements in the presence of
* timestamps.
* Andrey Savochkin: Check sequence numbers correctly when
* removing SACKs due to in sequence incoming
* data segments.
* Andi Kleen: Make sure we never ack data there is not
* enough room for. Also make this condition
* a fatal error if it might still happen.
* Andi Kleen: Add tcp_measure_rcv_mss to make
* connections with MSS<min(MTU,ann. MSS)
* work without delayed acks.
* Andi Kleen: Process packets with PSH set in the
* fast path.
* J Hadi Salim: ECN support
* Andrei Gurtov,
* Pasi Sarolahti,
* Panu Kuhlberg: Experimental audit of TCP (re)transmission
* engine. Lots of bugs are found.
* Pasi Sarolahti: F-RTO for dealing with spurious RTOs
*/
#define pr_fmt(fmt) "TCP: " fmt
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/sysctl.h>
#include <linux/kernel.h>
#include <linux/prefetch.h>
#include <net/dst.h>
#include <net/tcp.h>
#include <net/inet_common.h>
#include <linux/ipsec.h>
#include <asm/unaligned.h>
#include <linux/errqueue.h>
int sysctl_tcp_timestamps __read_mostly = 1;
int sysctl_tcp_window_scaling __read_mostly = 1;
int sysctl_tcp_sack __read_mostly = 1;
int sysctl_tcp_fack __read_mostly = 1;
int sysctl_tcp_max_reordering __read_mostly = 300;
int sysctl_tcp_dsack __read_mostly = 1;
int sysctl_tcp_app_win __read_mostly = 31;
int sysctl_tcp_adv_win_scale __read_mostly = 1;
EXPORT_SYMBOL(sysctl_tcp_adv_win_scale);
/* rfc5961 challenge ack rate limiting */
int sysctl_tcp_challenge_ack_limit = 1000;
int sysctl_tcp_stdurg __read_mostly;
int sysctl_tcp_rfc1337 __read_mostly;
int sysctl_tcp_max_orphans __read_mostly = NR_FILE;
int sysctl_tcp_frto __read_mostly = 2;
int sysctl_tcp_min_rtt_wlen __read_mostly = 300;
int sysctl_tcp_thin_dupack __read_mostly;
int sysctl_tcp_moderate_rcvbuf __read_mostly = 1;
int sysctl_tcp_early_retrans __read_mostly = 3;
int sysctl_tcp_invalid_ratelimit __read_mostly = HZ/2;
#define FLAG_DATA 0x01
/* Incoming frame contained data. */
#define FLAG_WIN_UPDATE 0x02
/* Incoming ACK was a window update. */
#define FLAG_DATA_ACKED 0x04
/* This ACK acknowledged new data. */
#define FLAG_RETRANS_DATA_ACKED 0x08
/* "" "" some of which was retransmitted. */
#define FLAG_SYN_ACKED 0x10
/* This ACK acknowledged SYN. */
#define FLAG_DATA_SACKED 0x20
/* New SACK. */
#define FLAG_ECE 0x40
/* ECE in this ACK */
#define FLAG_LOST_RETRANS 0x80
/* This ACK marks some retransmission lost */
#define FLAG_SLOWPATH 0x100
/* Do not skip RFC checks for window update.*/
#define FLAG_ORIG_SACK_ACKED 0x200
/* Never retransmitted data are (s)acked */
#define FLAG_SND_UNA_ADVANCED 0x400
/* Snd_una was changed (!= FLAG_DATA_ACKED) */
#define FLAG_DSACKING_ACK 0x800
/* SACK blocks contained D-SACK info */
#define FLAG_SACK_RENEGING 0x2000
/* snd_una advanced to a sacked seq */
#define FLAG_UPDATE_TS_RECENT 0x4000
/* tcp_replace_ts_recent() */
#define FLAG_ACKED (FLAG_DATA_ACKED|FLAG_SYN_ACKED)
#define FLAG_NOT_DUP (FLAG_DATA|FLAG_WIN_UPDATE|FLAG_ACKED)
#define FLAG_CA_ALERT (FLAG_DATA_SACKED|FLAG_ECE)
#define FLAG_FORWARD_PROGRESS (FLAG_ACKED|FLAG_DATA_SACKED)
#define TCP_REMNANT (TCP_FLAG_FIN|TCP_FLAG_URG|TCP_FLAG_SYN|TCP_FLAG_PSH)
#define TCP_HP_BITS (~(TCP_RESERVED_BITS|TCP_FLAG_PSH))
#define REXMIT_NONE 0
/* no loss recovery to do */
#define REXMIT_LOST 1
/* retransmit packets marked lost */
#define REXMIT_NEW 2
/* FRTO-style transmit of unsent/new packets */
/* Adapt the MSS value used to make delayed ack decision to the
* real world.
*/
static void tcp_measure_rcv_mss(struct sock *sk, const struct sk_buff *skb)
{
struct inet_connection_sock *icsk = inet_csk(sk);
const unsigned int lss = icsk->icsk_ack.last_seg_size;
unsigned int len;
icsk->icsk_ack.last_seg_size = 0;
/* skb->len may jitter because of SACKs, even if peer
* sends good full-sized frames.
*/
len = skb_shinfo(skb)->gso_size ? : skb->len;
if (len >= icsk->icsk_ack.rcv_mss) {
icsk->icsk_ack.rcv_mss = len;
} else {
/* Otherwise, we make more careful check taking into account,
* that SACKs block is variable.
*
* "len" is invariant segment length, including TCP header.
*/
len += skb->data - skb_transport_header(skb);
if (len >= TCP_MSS_DEFAULT + sizeof(struct tcphdr) ||
/* If PSH is not set, packet should be
* full sized, provided peer TCP is not badly broken.
* This observation (if it is correct 8)) allows
* to handle super-low mtu links fairly.
*/
(len >= TCP_MIN_MSS + sizeof(struct tcphdr) &&
!(tcp_flag_word(tcp_hdr(skb)) & TCP_REMNANT))) {
/* Subtract also invariant (if peer is RFC compliant),
* tcp header plus fixed timestamp option length.
* Resulting "len" is MSS free of SACK jitter.
*/
len -= tcp_sk(sk)->tcp_header_len;
icsk->icsk_ack.last_seg_size = len;
if (len == lss) {
icsk->icsk_ack.rcv_mss = len;
return;
}
}
if (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)
icsk->icsk_ack.pending |= ICSK_ACK_PUSHED2;
icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| pre-git | pre-git | 127 | 63.18% | 9 | 56.25% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 45 | 22.39% | 3 | 18.75% |
| alexey kuznetsov | alexey kuznetsov | 18 | 8.96% | 1 | 6.25% |
| herbert xu | herbert xu | 8 | 3.98% | 1 | 6.25% |
| linus torvalds | linus torvalds | 2 | 1.00% | 1 | 6.25% |
| william allen simpson | william allen simpson | 1 | 0.50% | 1 | 6.25% |
| Total | 201 | 100.00% | 16 | 100.00% |
static void tcp_incr_quickack(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
unsigned int quickacks = tcp_sk(sk)->rcv_wnd / (2 * icsk->icsk_ack.rcv_mss);
if (quickacks == 0)
quickacks = 2;
if (quickacks > icsk->icsk_ack.quick)
icsk->icsk_ack.quick = min(quickacks, TCP_MAX_QUICKACKS);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| pre-git | pre-git | 49 | 65.33% | 5 | 62.50% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 22 | 29.33% | 1 | 12.50% |
| linus torvalds | linus torvalds | 3 | 4.00% | 1 | 12.50% |
| eric dumazet | eric dumazet | 1 | 1.33% | 1 | 12.50% |
| Total | 75 | 100.00% | 8 | 100.00% |
static void tcp_enter_quickack_mode(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
tcp_incr_quickack(sk);
icsk->icsk_ack.pingpong = 0;
icsk->icsk_ack.ato = TCP_ATO_MIN;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| pre-git | pre-git | 24 | 57.14% | 1 | 33.33% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 17 | 40.48% | 1 | 33.33% |
| stephen hemminger | stephen hemminger | 1 | 2.38% | 1 | 33.33% |
| Total | 42 | 100.00% | 3 | 100.00% |
/* Send ACKs quickly, if "quick" count is not exhausted
* and the session is not interactive.
*/
static bool tcp_in_quickack_mode(struct sock *sk)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
const struct dst_entry *dst = __sk_dst_get(sk);
return (dst && dst_metric(dst, RTAX_QUICKACK)) ||
(icsk->icsk_ack.quick && !icsk->icsk_ack.pingpong);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| jon maxwell | jon maxwell | 24 | 40.00% | 1 | 25.00% |
| pre-git | pre-git | 18 | 30.00% | 1 | 25.00% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 17 | 28.33% | 1 | 25.00% |
| eric dumazet | eric dumazet | 1 | 1.67% | 1 | 25.00% |
| Total | 60 | 100.00% | 4 | 100.00% |
static void tcp_ecn_queue_cwr(struct tcp_sock *tp)
{
if (tp->ecn_flags & TCP_ECN_OK)
tp->ecn_flags |= TCP_ECN_QUEUE_CWR;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 24 | 96.00% | 1 | 50.00% |
| florian westphal | florian westphal | 1 | 4.00% | 1 | 50.00% |
| Total | 25 | 100.00% | 2 | 100.00% |
static void tcp_ecn_accept_cwr(struct tcp_sock *tp, const struct sk_buff *skb)
{
if (tcp_hdr(skb)->cwr)
tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 31 | 93.94% | 1 | 33.33% |
| florian westphal | florian westphal | 1 | 3.03% | 1 | 33.33% |
| eric dumazet | eric dumazet | 1 | 3.03% | 1 | 33.33% |
| Total | 33 | 100.00% | 3 | 100.00% |
static void tcp_ecn_withdraw_cwr(struct tcp_sock *tp)
{
tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 17 | 94.44% | 1 | 50.00% |
| florian westphal | florian westphal | 1 | 5.56% | 1 | 50.00% |
| Total | 18 | 100.00% | 2 | 100.00% |
static void __tcp_ecn_check_ce(struct tcp_sock *tp, const struct sk_buff *skb)
{
switch (TCP_SKB_CB(skb)->ip_dsfield & INET_ECN_MASK) {
case INET_ECN_NOT_ECT:
/* Funny extension: if ECT is not set on a segment,
* and we already seen ECT on a previous segment,
* it is probably a retransmit.
*/
if (tp->ecn_flags & TCP_ECN_SEEN)
tcp_enter_quickack_mode((struct sock *)tp);
break;
case INET_ECN_CE:
if (tcp_ca_needs_ecn((struct sock *)tp))
tcp_ca_event((struct sock *)tp, CA_EVENT_ECN_IS_CE);
if (!(tp->ecn_flags & TCP_ECN_DEMAND_CWR)) {
/* Better not delay acks, sender can have a very low cwnd */
tcp_enter_quickack_mode((struct sock *)tp);
tp->ecn_flags |= TCP_ECN_DEMAND_CWR;
}
tp->ecn_flags |= TCP_ECN_SEEN;
break;
default:
if (tcp_ca_needs_ecn((struct sock *)tp))
tcp_ca_event((struct sock *)tp, CA_EVENT_ECN_NO_CE);
tp->ecn_flags |= TCP_ECN_SEEN;
break;
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| florian westphal | florian westphal | 57 | 38.26% | 2 | 33.33% |
| eric dumazet | eric dumazet | 55 | 36.91% | 3 | 50.00% |
| ilpo jarvinen | ilpo jarvinen | 37 | 24.83% | 1 | 16.67% |
| Total | 149 | 100.00% | 6 | 100.00% |
static void tcp_ecn_check_ce(struct tcp_sock *tp, const struct sk_buff *skb)
{
if (tp->ecn_flags & TCP_ECN_OK)
__tcp_ecn_check_ce(tp, skb);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| florian westphal | florian westphal | 32 | 100.00% | 1 | 100.00% |
| Total | 32 | 100.00% | 1 | 100.00% |
static void tcp_ecn_rcv_synack(struct tcp_sock *tp, const struct tcphdr *th)
{
if ((tp->ecn_flags & TCP_ECN_OK) && (!th->ece || th->cwr))
tp->ecn_flags &= ~TCP_ECN_OK;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 43 | 95.56% | 1 | 33.33% |
| eric dumazet | eric dumazet | 1 | 2.22% | 1 | 33.33% |
| florian westphal | florian westphal | 1 | 2.22% | 1 | 33.33% |
| Total | 45 | 100.00% | 3 | 100.00% |
static void tcp_ecn_rcv_syn(struct tcp_sock *tp, const struct tcphdr *th)
{
if ((tp->ecn_flags & TCP_ECN_OK) && (!th->ece || !th->cwr))
tp->ecn_flags &= ~TCP_ECN_OK;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 44 | 95.65% | 1 | 33.33% |
| florian westphal | florian westphal | 1 | 2.17% | 1 | 33.33% |
| eric dumazet | eric dumazet | 1 | 2.17% | 1 | 33.33% |
| Total | 46 | 100.00% | 3 | 100.00% |
static bool tcp_ecn_rcv_ecn_echo(const struct tcp_sock *tp, const struct tcphdr *th)
{
if (th->ece && !th->syn && (tp->ecn_flags & TCP_ECN_OK))
return true;
return false;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 37 | 86.05% | 1 | 25.00% |
| eric dumazet | eric dumazet | 5 | 11.63% | 2 | 50.00% |
| florian westphal | florian westphal | 1 | 2.33% | 1 | 25.00% |
| Total | 43 | 100.00% | 4 | 100.00% |
/* Buffer size and advertised window tuning.
*
* 1. Tuning sk->sk_sndbuf, when connection enters established state.
*/
static void tcp_sndbuf_expand(struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
int sndmem, per_mss;
u32 nr_segs;
/* Worst case is non GSO/TSO : each frame consumes one skb
* and skb->head is kmalloced using power of two area of memory
*/
per_mss = max_t(u32, tp->rx_opt.mss_clamp, tp->mss_cache) +
MAX_TCP_HEADER +
SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
per_mss = roundup_pow_of_two(per_mss) +
SKB_DATA_ALIGN(sizeof(struct sk_buff));
nr_segs = max_t(u32, TCP_INIT_CWND, tp->snd_cwnd);
nr_segs = max_t(u32, nr_segs, tp->reordering + 1);
/* Fast Recovery (RFC 5681 3.2) :
* Cubic needs 1.7 factor, rounded to 2 to include
* extra cushion (application might react slowly to POLLOUT)
*/
sndmem = 2 * nr_segs * per_mss;
if (sk->sk_sndbuf < sndmem)
sk->sk_sndbuf = min(sndmem, sysctl_tcp_wmem[2]);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| eric dumazet | eric dumazet | 94 | 70.15% | 2 | 22.22% |
| pre-git | pre-git | 31 | 23.13% | 3 | 33.33% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 5 | 3.73% | 3 | 33.33% |
| david s. miller | david s. miller | 4 | 2.99% | 1 | 11.11% |
| Total | 134 | 100.00% | 9 | 100.00% |
/* 2. Tuning advertised window (window_clamp, rcv_ssthresh)
*
* All tcp_full_space() is split to two parts: "network" buffer, allocated
* forward and advertised in receiver window (tp->rcv_wnd) and
* "application buffer", required to isolate scheduling/application
* latencies from network.
* window_clamp is maximal advertised window. It can be less than
* tcp_full_space(), in this case tcp_full_space() - window_clamp
* is reserved for "application" buffer. The less window_clamp is
* the smoother our behaviour from viewpoint of network, but the lower
* throughput and the higher sensitivity of the connection to losses. 8)
*
* rcv_ssthresh is more strict window_clamp used at "slow start"
* phase to predict further behaviour of this connection.
* It is used for two goals:
* - to enforce header prediction at sender, even when application
* requires some significant "application buffer". It is check #1.
* - to prevent pruning of receive queue because of misprediction
* of receiver window. Check #2.
*
* The scheme does not work when sender sends good segments opening
* window and then starts to feed us spaghetti. But it should work
* in common situations. Otherwise, we have to rely on queue collapsing.
*/
/* Slow part of check#2. */
static int __tcp_grow_window(const struct sock *sk, const struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
/* Optimize this! */
int truesize = tcp_win_from_space(skb->truesize) >> 1;
int window = tcp_win_from_space(sysctl_tcp_rmem[2]) >> 1;
while (tp->rcv_ssthresh <= window) {
if (truesize <= skb->len)
return 2 * inet_csk(sk)->icsk_ack.rcv_mss;
truesize >>= 1;
window >>= 1;
}
return 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| pre-git | pre-git | 69 | 72.63% | 4 | 50.00% |
| ilpo jarvinen | ilpo jarvinen | 10 | 10.53% | 1 | 12.50% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 7 | 7.37% | 1 | 12.50% |
| john heffner | john heffner | 5 | 5.26% | 1 | 12.50% |
| eric dumazet | eric dumazet | 4 | 4.21% | 1 | 12.50% |
| Total | 95 | 100.00% | 8 | 100.00% |
static void tcp_grow_window(struct sock *sk, const struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
/* Check #1 */
if (tp->rcv_ssthresh < tp->window_clamp &&
(int)tp->rcv_ssthresh < tcp_space(sk) &&
!tcp_under_memory_pressure(sk)) {
int incr;
/* Check #2. Increase window, if skb with such overhead
* will fit to rcvbuf in future.
*/
if (tcp_win_from_space(skb->truesize) <= skb->len)
incr = 2 * tp->advmss;
else
incr = __tcp_grow_window(sk, skb);
if (incr) {
incr = max_t(int, incr, 2 * skb->len);
tp->rcv_ssthresh = min(tp->rcv_ssthresh + incr,
tp->window_clamp);
inet_csk(sk)->icsk_ack.quick |= 1;
}
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| pre-git | pre-git | 106 | 74.65% | 6 | 46.15% |
| eric dumazet | eric dumazet | 17 | 11.97% | 3 | 23.08% |
| ilpo jarvinen | ilpo jarvinen | 10 | 7.04% | 1 | 7.69% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 5 | 3.52% | 1 | 7.69% |
| glauber costa | glauber costa | 3 | 2.11% | 1 | 7.69% |
| linus torvalds | linus torvalds | 1 | 0.70% | 1 | 7.69% |
| Total | 142 | 100.00% | 13 | 100.00% |
/* 3. Tuning rcvbuf, when connection enters established state. */
static void tcp_fixup_rcvbuf(struct sock *sk)
{
u32 mss = tcp_sk(sk)->advmss;
int rcvmem;
rcvmem = 2 * SKB_TRUESIZE(mss + MAX_TCP_HEADER) *
tcp_default_init_rwnd(mss);
/* Dynamic Right Sizing (DRS) has 2 to 3 RTT latency
* Allow enough cushion so that sender is not limited by our window
*/
if (sysctl_tcp_moderate_rcvbuf)
rcvmem <<= 2;
if (sk->sk_rcvbuf < rcvmem)
sk->sk_rcvbuf = min(rcvmem, sysctl_tcp_rmem[2]);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| pre-git | pre-git | 36 | 50.70% | 4 | 30.77% |
| eric dumazet | eric dumazet | 23 | 32.39% | 4 | 30.77% |
| yuchung cheng | yuchung cheng | 5 | 7.04% | 1 | 7.69% |
| david s. miller | david s. miller | 3 | 4.23% | 1 | 7.69% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 3 | 4.23% | 2 | 15.38% |
| linus torvalds | linus torvalds | 1 | 1.41% | 1 | 7.69% |
| Total | 71 | 100.00% | 13 | 100.00% |
/* 4. Try to fixup all. It is made immediately after connection enters
* established state.
*/
void tcp_init_buffer_space(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
int maxwin;
if (!(sk->sk_userlocks & SOCK_RCVBUF_LOCK))
tcp_fixup_rcvbuf(sk);
if (!(sk->sk_userlocks & SOCK_SNDBUF_LOCK))
tcp_sndbuf_expand(sk);
tp->rcvq_space.space = tp->rcv_wnd;
tp->rcvq_space.time = tcp_time_stamp;
tp->rcvq_space.seq = tp->copied_seq;
maxwin = tcp_full_space(sk);
if (tp->window_clamp >= maxwin) {
tp->window_clamp = maxwin;
if (sysctl_tcp_app_win && maxwin > 4 * tp->advmss)
tp->window_clamp = max(maxwin -
(maxwin >> sysctl_tcp_app_win),
4 * tp->advmss);
}
/* Force reservation of one segment. */
if (sysctl_tcp_app_win &&
tp->window_clamp > 2 * tp->advmss &&
tp->window_clamp + tp->advmss > maxwin)
tp->window_clamp = max(2 * tp->advmss, maxwin - tp->advmss);
tp->rcv_ssthresh = min(tp->rcv_ssthresh, tp->window_clamp);
tp->snd_cwnd_stamp = tcp_time_stamp;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| pre-git | pre-git | 166 | 81.37% | 8 | 53.33% |
| eric dumazet | eric dumazet | 19 | 9.31% | 2 | 13.33% |
| david s. miller | david s. miller | 13 | 6.37% | 2 | 13.33% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 3 | 1.47% | 2 | 13.33% |
| linus torvalds | linus torvalds | 3 | 1.47% | 1 | 6.67% |
| Total | 204 | 100.00% | 15 | 100.00% |
/* 5. Recalculate window clamp after socket hit its memory bounds. */
static void tcp_clamp_window(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
struct inet_connection_sock *icsk = inet_csk(sk);
icsk->icsk_ack.quick = 0;
if (sk->sk_rcvbuf < sysctl_tcp_rmem[2] &&
!(sk->sk_userlocks & SOCK_RCVBUF_LOCK) &&
!tcp_under_memory_pressure(sk) &&
sk_memory_allocated(sk) < sk_prot_mem_limits(sk, 0)) {
sk->sk_rcvbuf = min(atomic_read(&sk->sk_rmem_alloc),
sysctl_tcp_rmem[2]);
}
if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf)
tp->rcv_ssthresh = min(tp->window_clamp, 2U * tp->advmss);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| pre-git | pre-git | 87 | 66.92% | 3 | 23.08% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 20 | 15.38% | 5 | 38.46% |
| glauber costa | glauber costa | 10 | 7.69% | 1 | 7.69% |
| ilpo jarvinen | ilpo jarvinen | 8 | 6.15% | 1 | 7.69% |
| linus torvalds | linus torvalds | 3 | 2.31% | 1 | 7.69% |
| john heffner | john heffner | 1 | 0.77% | 1 | 7.69% |
| eric dumazet | eric dumazet | 1 | 0.77% | 1 | 7.69% |
| Total | 130 | 100.00% | 13 | 100.00% |
/* Initialize RCV_MSS value.
* RCV_MSS is an our guess about MSS used by the peer.
* We haven't any direct information about the MSS.
* It's better to underestimate the RCV_MSS rather than overestimate.
* Overestimations make us ACKing less frequently than needed.
* Underestimations are more easy to detect and fix by tcp_measure_rcv_mss().
*/
void tcp_initialize_rcv_mss(struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
unsigned int hint = min_t(unsigned int, tp->advmss, tp->mss_cache);
hint = min(hint, tp->rcv_wnd / 2);
hint = min(hint, TCP_MSS_DEFAULT);
hint = max(hint, TCP_MIN_MSS);
inet_csk(sk)->icsk_ack.rcv_mss = hint;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| stephen hemminger | stephen hemminger | 74 | 97.37% | 1 | 33.33% |
| william allen simpson | william allen simpson | 1 | 1.32% | 1 | 33.33% |
| eric dumazet | eric dumazet | 1 | 1.32% | 1 | 33.33% |
| Total | 76 | 100.00% | 3 | 100.00% |
EXPORT_SYMBOL(tcp_initialize_rcv_mss);
/* Receiver "autotuning" code.
*
* The algorithm for RTT estimation w/o timestamps is based on
* Dynamic Right-Sizing (DRS) by Wu Feng and Mike Fisk of LANL.
* <http://public.lanl.gov/radiant/pubs.html#DRS>
*
* More detail on this code can be found at
* <http://staff.psc.edu/jheffner/>,
* though this reference is out of date. A new paper
* is pending.
*/
static void tcp_rcv_rtt_update(struct tcp_sock *tp, u32 sample, int win_dep)
{
u32 new_sample = tp->rcv_rtt_est.rtt;
long m = sample;
if (m == 0)
m = 1;
if (new_sample != 0) {
/* If we sample in larger samples in the non-timestamp
* case, we could grossly overestimate the RTT especially
* with chatty applications or bulk transfer apps which
* are stalled on filesystem I/O.
*
* Also, since we are only going for a minimum in the
* non-timestamp case, we do not smooth things out
* else with timestamps disabled convergence takes too
* long.
*/
if (!win_dep) {
m -= (new_sample >> 3);
new_sample += m;
} else {
m <<= 3;
if (m < new_sample)
new_sample = m;
}
} else {
/* No previous measure. */
new_sample = m << 3;
}
if (tp->rcv_rtt_est.rtt != new_sample)
tp->rcv_rtt_est.rtt = new_sample;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| david s. miller | david s. miller | 104 | 91.23% | 1 | 20.00% |
| neal cardwell | neal cardwell | 7 | 6.14% | 1 | 20.00% |
| stephen hemminger | stephen hemminger | 2 | 1.75% | 2 | 40.00% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 1 | 0.88% | 1 | 20.00% |
| Total | 114 | 100.00% | 5 | 100.00% |
static inline void tcp_rcv_rtt_measure(struct tcp_sock *tp)
{
if (tp->rcv_rtt_est.time == 0)
goto new_measure;
if (before(tp->rcv_nxt, tp->rcv_rtt_est.seq))
return;
tcp_rcv_rtt_update(tp, tcp_time_stamp - tp->rcv_rtt_est.time, 1);
new_measure:
tp->rcv_rtt_est.seq = tp->rcv_nxt + tp->rcv_wnd;
tp->rcv_rtt_est.time = tcp_time_stamp;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| david s. miller | david s. miller | 78 | 97.50% | 1 | 33.33% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 1 | 1.25% | 1 | 33.33% |
| neal cardwell | neal cardwell | 1 | 1.25% | 1 | 33.33% |
| Total | 80 | 100.00% | 3 | 100.00% |
static inline void tcp_rcv_rtt_measure_ts(struct sock *sk,
const struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
if (tp->rx_opt.rcv_tsecr &&
(TCP_SKB_CB(skb)->end_seq -
TCP_SKB_CB(skb)->seq >= inet_csk(sk)->icsk_ack.rcv_mss))
tcp_rcv_rtt_update(tp, tcp_time_stamp - tp->rx_opt.rcv_tsecr, 0);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| david s. miller | david s. miller | 54 | 71.05% | 1 | 33.33% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 22 | 28.95% | 2 | 66.67% |
| Total | 76 | 100.00% | 3 | 100.00% |
/*
* This function should be called every time data is copied to user space.
* It calculates the appropriate TCP receive buffer space.
*/
void tcp_rcv_space_adjust(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
int time;
int copied;
time = tcp_time_stamp - tp->rcvq_space.time;
if (time < (tp->rcv_rtt_est.rtt >> 3) || tp->rcv_rtt_est.rtt == 0)
return;
/* Number of bytes copied to user in last RTT */
copied = tp->copied_seq - tp->rcvq_space.seq;
if (copied <= tp->rcvq_space.space)
goto new_measure;
/* A bit of theory :
* copied = bytes received in previous RTT, our base window
* To cope with packet losses, we need a 2x factor
* To cope with slow start, and sender growing its cwin by 100 %
* every RTT, we need a 4x factor, because the ACK we are sending
* now is for the next RTT, not the current one :
* <prev RTT . ><current RTT .. ><next RTT .... >
*/
if (sysctl_tcp_moderate_rcvbuf &&
!(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
int rcvwin, rcvmem, rcvbuf;
/* minimal window to cope with packet losses, assuming
* steady state. Add some cushion because of small variations.
*/
rcvwin = (copied << 1) + 16 * tp->advmss;
/* If rate increased by 25%,
* assume slow start, rcvwin = 3 * copied
* If rate increased by 50%,
* assume sender can use 2x growth, rcvwin = 4 * copied
*/
if (copied >=
tp->rcvq_space.space + (tp->rcvq_space.space >> 2)) {
if (copied >=
tp->rcvq_space.space + (tp->rcvq_space.space >> 1))
rcvwin <<= 1;
else
rcvwin += (rcvwin >> 1);
}
rcvmem = SKB_TRUESIZE(tp->advmss + MAX_TCP_HEADER);
while (tcp_win_from_space(rcvmem) < tp->advmss)
rcvmem += 128;
rcvbuf = min(rcvwin / tp->advmss * rcvmem, sysctl_tcp_rmem[2]);
if (rcvbuf > sk->sk_rcvbuf) {
sk->sk_rcvbuf = rcvbuf;
/* Make the window clamp follow along. */
tp->window_clamp = rcvwin;
}
}
tp->rcvq_space.space = copied;
new_measure:
tp->rcvq_space.seq = tp->copied_seq;
tp->rcvq_space.time = tcp_time_stamp;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| david s. miller | david s. miller | 168 | 61.31% | 3 | 37.50% |
| eric dumazet | eric dumazet | 95 | 34.67% | 2 | 25.00% |
| john heffner | john heffner | 9 | 3.28% | 1 | 12.50% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 2 | 0.73% | 2 | 25.00% |
| Total | 274 | 100.00% | 8 | 100.00% |
/* There is something which you must keep in mind when you analyze the
* behavior of the tp->ato delayed ack timeout interval. When a
* connection starts up, we want to ack as quickly as possible. The
* problem is that "good" TCP's do slow start at the beginning of data
* transmission. The means that until we send the first few ACK's the
* sender will sit on his end and only queue most of his data, because
* he can only send snd_cwnd unacked packets at any given time. For
* each ACK we send, he increments snd_cwnd and transmits more of his
* queue. -DaveM
*/
static void tcp_event_data_recv(struct sock *sk, struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
struct inet_connection_sock *icsk = inet_csk(sk);
u32 now;
inet_csk_schedule_ack(sk);
tcp_measure_rcv_mss(sk, skb);
tcp_rcv_rtt_measure(tp);
now = tcp_time_stamp;
if (!icsk->icsk_ack.ato) {
/* The _first_ data packet received, initialize
* delayed ACK engine.
*/
tcp_incr_quickack(sk);
icsk->icsk_ack.ato = TCP_ATO_MIN;
} else {
int m = now - icsk->icsk_ack.lrcvtime;
if (m <= TCP_ATO_MIN / 2) {
/* The fastest case is the first. */
icsk->icsk_ack.ato = (icsk->icsk_ack.ato >> 1) + TCP_ATO_MIN / 2;
} else if (m < icsk->icsk_ack.ato) {
icsk->icsk_ack.ato = (icsk->icsk_ack.ato >> 1) + m;
if (icsk->icsk_ack.ato > icsk->icsk_rto)
icsk->icsk_ack.ato = icsk->icsk_rto;
} else if (m > icsk->icsk_rto) {
/* Too long gap. Apparently sender failed to
* restart window, so that we send ACKs quickly.
*/
tcp_incr_quickack(sk);
sk_mem_reclaim(sk);
}
}
icsk->icsk_ack.lrcvtime = now;
tcp_ecn_check_ce(tp, skb);
if (skb->len >= 128)
tcp_grow_window(sk, skb);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| pre-git | pre-git | 167 | 71.06% | 11 | 61.11% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 43 | 18.30% | 1 | 5.56% |
| ilpo jarvinen | ilpo jarvinen | 10 | 4.26% | 1 | 5.56% |
| linus torvalds | linus torvalds | 7 | 2.98% | 1 | 5.56% |
| david s. miller | david s. miller | 5 | 2.13% | 1 | 5.56% |
| stephen hemminger | stephen hemminger | 1 | 0.43% | 1 | 5.56% |
| florian westphal | florian westphal | 1 | 0.43% | 1 | 5.56% |
| hideo aoki | hideo aoki | 1 | 0.43% | 1 | 5.56% |
| Total | 235 | 100.00% | 18 | 100.00% |
/* Called to compute a smoothed rtt estimate. The data fed to this
* routine either comes from timestamps, or from segments that were
* known _not_ to have been retransmitted [see Karn/Partridge
* Proceedings SIGCOMM 87]. The algorithm is from the SIGCOMM 88
* piece by Van Jacobson.
* NOTE: the next three routines used to be one big routine.
* To save cycles in the RFC 1323 implementation it was better to break
* it up into three procedures. -- erics
*/
static void tcp_rtt_estimator(struct sock *sk, long mrtt_us)
{
struct tcp_sock *tp = tcp_sk(sk);
long m = mrtt_us; /* RTT */
u32 srtt = tp->srtt_us;
/* The following amusing code comes from Jacobson's
* article in SIGCOMM '88. Note that rtt and mdev
* are scaled versions of rtt and mean deviation.
* This is designed to be as fast as possible
* m stands for "measurement".
*
* On a 1990 paper the rto value is changed to:
* RTO = rtt + 4 * mdev
*
* Funny. This algorithm seems to be very broken.
* These formulae increase RTO, when it should be decreased, increase
* too slowly, when it should be increased quickly, decrease too quickly
* etc. I guess in BSD RTO takes ONE value, so that it is absolutely
* does not matter how to _calculate_ it. Seems, it was trap
* that VJ failed to avoid. 8)
*/
if (srtt != 0) {
m -= (srtt >> 3); /* m is now error in rtt est */
srtt += m; /* rtt = 7/8 rtt + 1/8 new */
if (m < 0) {
m = -m; /* m is now abs(error) */
m -= (tp->mdev_us >> 2); /* similar update on mdev */
/* This is similar to one of Eifel findings.
* Eifel blocks mdev updates when rtt decreases.
* This solution is a bit different: we use finer gain
* for mdev in this case (alpha*beta).
* Like Eifel it also prevents growth of rto,
* but also it limits too fast rto decreases,
* happening in pure Eifel.
*/
if (m > 0)
m >>= 3;
} else {
m -= (tp->mdev_us >> 2); /* similar update on mdev */
}
tp->mdev_us += m; /* mdev = 3/4 mdev + 1/4 new */
if (tp->mdev_us > tp->mdev_max_us) {
tp->mdev_max_us = tp->mdev_us;
if (tp->mdev_max_us > tp->rttvar_us)
tp->rttvar_us = tp->mdev_max_us;
}
if (after(tp->snd_una, tp->rtt_seq)) {
if (tp->mdev_max_us < tp->rttvar_us)
tp->rttvar_us -= (tp->rttvar_us - tp->mdev_max_us) >> 2;
tp->rtt_seq = tp->snd_nxt;
tp->mdev_max_us = tcp_rto_min_us(sk);
}
} else {
/* no previous measure. */
srtt = m << 3; /* take the measured time to be rtt */
tp->mdev_us = m << 1; /* make sure rto = 3*rtt */
tp->rttvar_us = max(tp->mdev_us, tcp_rto_min_us(sk));
tp->mdev_max_us = tp->rttvar_us;
tp->rtt_seq = tp->snd_nxt;
}
tp->srtt_us = max(1U, srtt);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| pre-git | pre-git | 203 | 73.55% | 6 | 42.86% |
| eric dumazet | eric dumazet | 51 | 18.48% | 2 | 14.29% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 12 | 4.35% | 1 | 7.14% |
| david s. miller | david s. miller | 6 | 2.17% | 1 | 7.14% |
| alexey kuznetsov | alexey kuznetsov | 2 | 0.72% | 2 | 14.29% |
| hideaki yoshifuji | hideaki yoshifuji | 1 | 0.36% | 1 | 7.14% |
| linus torvalds | linus torvalds | 1 | 0.36% | 1 | 7.14% |
| Total | 276 | 100.00% | 14 | 100.00% |
/* Set the sk_pacing_rate to allow proper sizing of TSO packets.
* Note: TCP stack does not yet implement pacing.
* FQ packet scheduler can be used to implement cheap but effective
* TCP pacing, to smooth the burst on large writes when packets
* in flight is significantly lower than cwnd (or rwin)
*/
int sysctl_tcp_pacing_ss_ratio __read_mostly = 200;
int sysctl_tcp_pacing_ca_ratio __read_mostly = 120;
static void tcp_update_pacing_rate(struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
u64 rate;
/* set sk_pacing_rate to 200 % of current rate (mss * cwnd / srtt) */
rate = (u64)tp->mss_cache * ((USEC_PER_SEC / 100) << 3);
/* current rate is (cwnd * mss) / srtt
* In Slow Start [1], set sk_pacing_rate to 200 % the current rate.
* In Congestion Avoidance phase, set it to 120 % the current rate.
*
* [1] : Normal Slow Start condition is (tp->snd_cwnd < tp->snd_ssthresh)
* If snd_cwnd >= (tp->snd_ssthresh / 2), we are approaching
* end of slow start and should slow down.
*/
if (tp->snd_cwnd < tp->snd_ssthresh / 2)
rate *= sysctl_tcp_pacing_ss_ratio;
else
rate *= sysctl_tcp_pacing_ca_ratio;
rate *= max(tp->snd_cwnd, tp->packets_out);
if (likely(tp->srtt_us))
do_div(rate, tp->srtt_us);
/* ACCESS_ONCE() is needed because sch_fq fetches sk_pacing_rate
* without any lock. We want to make sure compiler wont store
* intermediate values in this location.
*/
ACCESS_ONCE(sk->sk_pacing_rate) = min_t(u64, rate,
sk->sk_max_pacing_rate);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| eric dumazet | eric dumazet | 117 | 100.00% | 5 | 100.00% |
| Total | 117 | 100.00% | 5 | 100.00% |
/* Calculate rto without backoff. This is the second half of Van Jacobson's
* routine referred to above.
*/
static void tcp_set_rto(struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
/* Old crap is replaced with new one. 8)
*
* More seriously:
* 1. If rtt variance happened to be less 50msec, it is hallucination.
* It cannot be less due to utterly erratic ACK generation made
* at least by solaris and freebsd. "Erratic ACKs" has _nothing_
* to do with delayed acks, because at cwnd>2 true delack timeout
* is invisible. Actually, Linux-2.4 also generates erratic
* ACKs in some circumstances.
*/
inet_csk(sk)->icsk_rto = __tcp_set_rto(tp);
/* 2. Fixups made earlier cannot be right.
* If we do not estimate RTO correctly without them,
* all the algo is pure shit and should be replaced
* with correct one. It is exactly, which we pretend to do.
*/
/* NOTE: clamping at TCP_RTO_MIN is not required, current algo
* guarantees that rto is higher.
*/
tcp_bound_rto(sk);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 20 | 47.62% | 1 | 11.11% |
| pre-git | pre-git | 14 | 33.33% | 4 | 44.44% |
| damian lukowski | damian lukowski | 4 | 9.52% | 1 | 11.11% |
| stephen hemminger | stephen hemminger | 3 | 7.14% | 2 | 22.22% |
| ilpo jarvinen | ilpo jarvinen | 1 | 2.38% | 1 | 11.11% |
| Total | 42 | 100.00% | 9 | 100.00% |
__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst)
{
__u32 cwnd = (dst ? dst_metric(dst, RTAX_INITCWND) : 0);
if (!cwnd)
cwnd = TCP_INIT_CWND;
return min_t(__u32, cwnd, tp->snd_cwnd_clamp);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| david s. miller | david s. miller | 54 | 100.00% | 1 | 100.00% |
| Total | 54 | 100.00% | 1 | 100.00% |
/*
* Packet counting of FACK is based on in-order assumptions, therefore TCP
* disables it when reordering is detected
*/
void tcp_disable_fack(struct tcp_sock *tp)
{
/* RFC3517 uses different metric in lost marker => reset on change */
if (tcp_is_fack(tp))
tp->lost_skb_hint = NULL;
tp->rx_opt.sack_ok &= ~TCP_FACK_ENABLED;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| david s. miller | david s. miller | 20 | 60.61% | 1 | 20.00% |
| pre-git | pre-git | 11 | 33.33% | 3 | 60.00% |
| alexey kuznetsov | alexey kuznetsov | 2 | 6.06% | 1 | 20.00% |
| Total | 33 | 100.00% | 5 | 100.00% |
/* Take a notice that peer is sending D-SACKs */
static void tcp_dsack_seen(struct tcp_sock *tp)
{
tp->rx_opt.sack_ok |= TCP_DSACK_SEEN;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| david s. miller | david s. miller | 13 | 68.42% | 1 | 25.00% |
| jiri kosina | jiri kosina | 3 | 15.79% | 1 | 25.00% |
| pre-git | pre-git | 3 | 15.79% | 2 | 50.00% |
| Total | 19 | 100.00% | 4 | 100.00% |
static void tcp_update_reordering(struct sock *sk, const int metric,
const int ts)
{
struct tcp_sock *tp = tcp_sk(sk);
if (metric > tp->reordering) {
int mib_idx;
tp->reordering = min(sysctl_tcp_max_reordering, metric);
/* This exciting event is worth to be remembered. 8) */
if (ts)
mib_idx = LINUX_MIB_TCPTSREORDER;
else if (tcp_is_reno(tp))
mib_idx = LINUX_MIB_TCPRENOREORDER;
else if (tcp_is_fack(tp))
mib_idx = LINUX_MIB_TCPFACKREORDER;
else
mib_idx = LINUX_MIB_TCPSACKREORDER;
NET_INC_STATS(sock_net(sk), mib_idx);
#if FASTRETRANS_DEBUG > 1
pr_debug("Disorder%d %d %u f%u s%u rr%d\n",
tp->rx_opt.sack_ok, inet_csk(sk)->icsk_ca_state,
tp->reordering,
tp->fackets_out,
tp->sacked_out,
tp->undo_marker ? tp->undo_retrans : 0);
#endif
tcp_disable_fack(tp);
}
if (metric > 0)
tcp_disable_early_retrans(tp);
tp->rack.reord = 1;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| pre-git | pre-git | 99 | 57.56% | 8 | 38.10% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 21 | 12.21% | 2 | 9.52% |
| pavel emelianov | pavel emelianov | 19 | 11.05% | 2 | 9.52% |
| yuchung cheng | yuchung cheng | 19 | 11.05% | 2 | 9.52% |
| ilpo jarvinen | ilpo jarvinen | 5 | 2.91% | 1 | 4.76% |
| linus torvalds | linus torvalds | 3 | 1.74% | 2 | 9.52% |
| hideaki yoshifuji | hideaki yoshifuji | 3 | 1.74% | 1 | 4.76% |
| eric dumazet | eric dumazet | 2 | 1.16% | 2 | 9.52% |
| joe perches | joe perches | 1 | 0.58% | 1 | 4.76% |
| Total | 172 | 100.00% | 21 | 100.00% |
/* This must be called before lost_out is incremented */
static void tcp_verify_retransmit_hint(struct tcp_sock *tp, struct sk_buff *skb)
{
if (!tp->retransmit_skb_hint ||
before(TCP_SKB_CB(skb)->seq,
TCP_SKB_CB(tp->retransmit_skb_hint)->seq))
tp->retransmit_skb_hint = skb;
if (!tp->lost_out ||
after(TCP_SKB_CB(skb)->end_seq, tp->retransmit_high))
tp->retransmit_high = TCP_SKB_CB(skb)->end_seq;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 79 | 98.75% | 2 | 66.67% |
| ian morris | ian morris | 1 | 1.25% | 1 | 33.33% |
| Total | 80 | 100.00% | 3 | 100.00% |
static void tcp_skb_mark_lost(struct tcp_sock *tp, struct sk_buff *skb)
{
if (!(TCP_SKB_CB(skb)->sacked & (TCPCB_LOST|TCPCB_SACKED_ACKED))) {
tcp_verify_retransmit_hint(tp, skb);
tp->lost_out += tcp_skb_pcount(skb);
TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 61 | 100.00% | 1 | 100.00% |
| Total | 61 | 100.00% | 1 | 100.00% |
void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb)
{
tcp_verify_retransmit_hint(tp, skb);
if (!(TCP_SKB_CB(skb)->sacked & (TCPCB_LOST|TCPCB_SACKED_ACKED))) {
tp->lost_out += tcp_skb_pcount(skb);
TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 60 | 100.00% | 1 | 100.00% |
| Total | 60 | 100.00% | 1 | 100.00% |
/* This procedure tags the retransmission queue when SACKs arrive.
*
* We have three tag bits: SACKED(S), RETRANS(R) and LOST(L).
* Packets in queue with these bits set are counted in variables
* sacked_out, retrans_out and lost_out, correspondingly.
*
* Valid combinations are:
* Tag InFlight Description
* 0 1 - orig segment is in flight.
* S 0 - nothing flies, orig reached receiver.
* L 0 - nothing flies, orig lost by net.
* R 2 - both orig and retransmit are in flight.
* L|R 1 - orig is lost, retransmit is in flight.
* S|R 1 - orig reached receiver, retrans is still in flight.
* (L|S|R is logically valid, it could occur when L|R is sacked,
* but it is equivalent to plain S and code short-curcuits it to S.
* L|S is logically invalid, it would mean -1 packet in flight 8))
*
* These 6 states form finite state machine, controlled by the following events:
* 1. New ACK (+SACK) arrives. (tcp_sacktag_write_queue())
* 2. Retransmission. (tcp_retransmit_skb(), tcp_xmit_retransmit_queue())
* 3. Loss detection event of two flavors:
* A. Scoreboard estimator decided the packet is lost.
* A'. Reno "three dupacks" marks head of queue lost.
* A''. Its FACK modification, head until snd.fack is lost.
* B. SACK arrives sacking SND.NXT at the moment, when the
* segment was retransmitted.
* 4. D-SACK added new rule: D-SACK changes any tag to S.
*
* It is pleasant to note, that state diagram turns out to be commutative,
* so that we are allowed not to be bothered by order of our actions,
* when multiple events arrive simultaneously. (see the function below).
*
* Reordering detection.
* --------------------
* Reordering metric is maximal distance, which a packet can be displaced
* in packet stream. With SACKs we can estimate it:
*
* 1. SACK fills old hole and the corresponding segment was not
* ever retransmitted -> reordering. Alas, we cannot use it
* when segment was retransmitted.
* 2. The last flaw is solved with D-SACK. D-SACK arrives
* for retransmitted and already SACKed segment -> reordering..
* Both of these heuristics are not used in Loss state, when we cannot
* account for retransmits accurately.
*
* SACK block validation.
* ----------------------
*
* SACK block range validation checks that the received SACK block fits to
* the expected sequence limits, i.e., it is between SND.UNA and SND.NXT.
* Note that SND.UNA is not included to the range though being valid because
* it means that the receiver is rather inconsistent with itself reporting
* SACK reneging when it should advance SND.UNA. Such SACK block this is
* perfectly valid, however, in light of RFC2018 which explicitly states
* that "SACK block MUST reflect the newest segment. Even if the newest
* segment is going to be discarded ...", not that it looks very clever
* in case of head skb. Due to potentional receiver driven attacks, we
* choose to avoid immediate execution of a walk in write queue due to
* reneging and defer head skb's loss recovery to standard loss recovery
* procedure that will eventually trigger (nothing forbids us doing this).
*
* Implements also blockage to start_seq wrap-around. Problem lies in the
* fact that though start_seq (s) is before end_seq (i.e., not reversed),
* there's no guarantee that it will be before snd_nxt (n). The problem
* happens when start_seq resides between end_seq wrap (e_w) and snd_nxt
* wrap (s_w):
*
* <- outs wnd -> <- wrapzone ->
* u e n u_w e_w s n_w
* | | | | | | |
* |<------------+------+----- TCP seqno space --------------+---------->|
* ...-- <2^31 ->| |<--------...
* ...---- >2^31 ------>| |<--------...
*
* Current code wouldn't be vulnerable but it's better still to discard such
* crazy SACK blocks. Doing this check for start_seq alone closes somewhat
* similar case (end_seq after snd_nxt wrap) as earlier reversed check in
* snd_nxt wrap -> snd_una region will then become "well defined", i.e.,
* equal to the ideal case (infinite seqno space without wrap caused issues).
*
* With D-SACK the lower bound is extended to cover sequence space below
* SND.UNA down to undo_marker, which is the last point of interest. Yet
* again, D-SACK block must not to go across snd_una (for the same reason as
* for the normal SACK blocks, explained above). But there all simplicity
* ends, TCP might receive valid D-SACKs below that. As long as they reside
* fully below undo_marker they do not affect behavior in anyway and can
* therefore be safely ignored. In rare cases (which are more or less
* theoretical ones), the D-SACK will nicely cross that boundary due to skb
* fragmentation and packet reordering past skb's retransmission. To consider
* them correctly, the acceptable range must be extended even more though
* the exact amount is rather hard to quantify. However, tp->max_window can
* be used as an exaggerated estimate.
*/
static bool tcp_is_sackblock_valid(struct tcp_sock *tp, bool is_dsack,
u32 start_seq, u32 end_seq)
{
/* Too far in future, or reversed (interpretation is ambiguous) */
if (after(end_seq, tp->snd_nxt) || !before(start_seq, end_seq))
return false;
/* Nasty start_seq wrap-around check (see comments above) */
if (!before(start_seq, tp->snd_nxt))
return false;
/* In outstanding window? ...This is valid exit for D-SACKs too.
* start_seq == snd_una is non-sensical (see comments above)
*/
if (after(start_seq, tp->snd_una))
return true;
if (!is_dsack || !tp->undo_marker)
return false;
/* ...Then it's D-SACK, and must reside below snd_una completely */
if (after(end_seq, tp->snd_una))
return false;
if (!before(start_seq, tp->undo_marker))
return true;
/* Too old */
if (!after(end_seq, tp->undo_marker))
return false;
/* Undo_marker boundary crossing (overestimates a lot). Known already:
* start_seq < undo_marker and end_seq >= undo_marker.
*/
return !before(start_seq, end_seq - tp->max_window);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 137 | 93.20% | 1 | 33.33% |
| eric dumazet | eric dumazet | 9 | 6.12% | 1 | 33.33% |
| ryousei takano | ryousei takano | 1 | 0.68% | 1 | 33.33% |
| Total | 147 | 100.00% | 3 | 100.00% |
static bool tcp_check_dsack(struct sock *sk, const struct sk_buff *ack_skb,
struct tcp_sack_block_wire *sp, int num_sacks,
u32 prior_snd_una)
{
struct tcp_sock *tp = tcp_sk(sk);
u32 start_seq_0 = get_unaligned_be32(&sp[0].start_seq);
u32 end_seq_0 = get_unaligned_be32(&sp[0].end_seq);
bool dup_sack = false;
if (before(start_seq_0, TCP_SKB_CB(ack_skb)->ack_seq)) {
dup_sack = true;
tcp_dsack_seen(tp);
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPDSACKRECV);
} else if (num_sacks > 1) {
u32 end_seq_1 = get_unaligned_be32(&sp[1].end_seq);
u32 start_seq_1 = get_unaligned_be32(&sp[1].start_seq);
if (!after(end_seq_0, end_seq_1) &&
!before(start_seq_0, start_seq_1)) {
dup_sack = true;
tcp_dsack_seen(tp);
NET_INC_STATS(sock_net(sk),
LINUX_MIB_TCPDSACKOFORECV);
}
}
/* D-SACK for already forgotten data... Do dumb counting. */
if (dup_sack && tp->undo_marker && tp->undo_retrans > 0 &&
!after(end_seq_0, prior_snd_una) &&
after(end_seq_0, tp->undo_marker))
tp->undo_retrans--;
return dup_sack;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| david s. miller | david s. miller | 172 | 77.48% | 1 | 10.00% |
| pavel emelianov | pavel emelianov | 22 | 9.91% | 2 | 20.00% |
| yuchung cheng | yuchung cheng | 10 | 4.50% | 2 | 20.00% |
| eric dumazet | eric dumazet | 8 | 3.60% | 3 | 30.00% |
| ilpo jarvinen | ilpo jarvinen | 6 | 2.70% | 1 | 10.00% |
| harvey harrison | harvey harrison | 4 | 1.80% | 1 | 10.00% |
| Total | 222 | 100.00% | 10 | 100.00% |
struct tcp_sacktag_state {
int reord;
int fack_count;
/* Timestamps for earliest and latest never-retransmitted segment
* that was SACKed. RTO needs the earliest RTT to stay conservative,
* but congestion control should still get an accurate delay signal.
*/
struct skb_mstamp first_sackt;
struct skb_mstamp last_sackt;
int flag;
};
/* Check if skb is fully within the SACK block. In presence of GSO skbs,
* the incoming SACK may not exactly match but we can find smaller MSS
* aligned portion of it that matches. Therefore we might need to fragment
* which may fail and creates some hassle (caller must handle error case
* returns).
*
* FIXME: this could be merged to shift decision code
*/
static int tcp_match_skb_to_sack(struct sock *sk, struct sk_buff *skb,
u32 start_seq, u32 end_seq)
{
int err;
bool in_sack;
unsigned int pkt_len;
unsigned int mss;
in_sack = !after(start_seq, TCP_SKB_CB(skb)->seq) &&
!before(end_seq, TCP_SKB_CB(skb)->end_seq);
if (tcp_skb_pcount(skb) > 1 && !in_sack &&
after(TCP_SKB_CB(skb)->end_seq, start_seq)) {
mss = tcp_skb_mss(skb);
in_sack = !after(start_seq, TCP_SKB_CB(skb)->seq);
if (!in_sack) {
pkt_len = start_seq - TCP_SKB_CB(skb)->seq;
if (pkt_len < mss)
pkt_len = mss;
} else {
pkt_len = end_seq - TCP_SKB_CB(skb)->seq;
if (pkt_len < mss)
return -EINVAL;
}
/* Round if necessary so that SACKs cover only full MSSes
* and/or the remaining small portion (if present)
*/
if (pkt_len > mss) {
unsigned int new_len = (pkt_len / mss) * mss;
if (!in_sack && new_len < pkt_len) {
new_len += mss;
if (new_len >= skb->len)
return 0;
}
pkt_len = new_len;
}
err = tcp_fragment(sk, skb, pkt_len, mss, GFP_ATOMIC);
if (err < 0)
return err;
}
return in_sack;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 235 | 97.11% | 2 | 33.33% |
| eric dumazet | eric dumazet | 3 | 1.24% | 1 | 16.67% |
| octavian purdila | octavian purdila | 2 | 0.83% | 1 | 16.67% |
| neal cardwell | neal cardwell | 1 | 0.41% | 1 | 16.67% |
| adrian bunk | adrian bunk | 1 | 0.41% | 1 | 16.67% |
| Total | 242 | 100.00% | 6 | 100.00% |
/* Mark the given newly-SACKed range as such, adjusting counters and hints. */
static u8 tcp_sacktag_one(struct sock *sk,
struct tcp_sacktag_state *state, u8 sacked,
u32 start_seq, u32 end_seq,
int dup_sack, int pcount,
const struct skb_mstamp *xmit_time)
{
struct tcp_sock *tp = tcp_sk(sk);
int fack_count = state->fack_count;
/* Account D-SACK for retransmitted packet. */
if (dup_sack && (sacked & TCPCB_RETRANS)) {
if (tp->undo_marker && tp->undo_retrans > 0 &&
after(end_seq, tp->undo_marker))
tp->undo_retrans--;
if (sacked & TCPCB_SACKED_ACKED)
state->reord = min(fack_count, state->reord);
}
/* Nothing to do; acked frame is about to be dropped (was ACKed). */
if (!after(end_seq, tp->snd_una))
return sacked;
if (!(sacked & TCPCB_SACKED_ACKED)) {
tcp_rack_advance(tp, xmit_time, sacked);
if (sacked & TCPCB_SACKED_RETRANS) {
/* If the segment is not tagged as lost,
* we do not clear RETRANS, believing
* that retransmission is still in flight.
*/
if (sacked & TCPCB_LOST) {
sacked &= ~(TCPCB_LOST|TCPCB_SACKED_RETRANS);
tp->lost_out -= pcount;
tp->retrans_out -= pcount;
}
} else {
if (!(sacked & TCPCB_RETRANS)) {
/* New sack for not retransmitted frame,
* which was in hole. It is reordering.
*/
if (before(start_seq,
tcp_highest_sack_seq(tp)))
state->reord = min(fack_count,
state->reord);
if (!after(end_seq, tp->high_seq))
state->flag |= FLAG_ORIG_SACK_ACKED;
if (state->first_sackt.v64 == 0)
state->first_sackt = *xmit_time;
state->last_sackt = *xmit_time;
}
if (sacked & TCPCB_LOST) {
sacked &= ~TCPCB_LOST;
tp->lost_out -= pcount;
}
}
sacked |= TCPCB_SACKED_ACKED;
state->flag |= FLAG_DATA_SACKED;
tp->sacked_out += pcount;
tp->delivered += pcount; /* Out-of-order packets delivered */
fack_count += pcount;
/* Lost marker hint past SACKed? Tweak RFC3517 cnt */
if (!tcp_is_fack(tp) && tp->lost_skb_hint &&
before(start_seq, TCP_SKB_CB(tp->lost_skb_hint)->seq))
tp->lost_cnt_hint += pcount;
if (fack_count > tp->fackets_out)
tp->fackets_out = fack_count;
}
/* D-SACK. We can detect redundant retransmission in S|R and plain R
* frames and clear it. undo_retrans is decreased above, L|R frames
* are accounted above as well.
*/
if (dup_sack && (sacked & TCPCB_SACKED_RETRANS)) {
sacked &= ~TCPCB_SACKED_RETRANS;
tp->retrans_out -= pcount;
}
return sacked;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 239 | 61.60% | 8 | 28.57% |
| yuchung cheng | yuchung cheng | 58 | 14.95% | 6 | 21.43% |
| baruch even | baruch even | 25 | 6.44% | 3 | 10.71% |
| pre-git | pre-git | 20 | 5.15% | 6 | 21.43% |
| stephen hemminger | stephen hemminger | 17 | 4.38% | 1 | 3.57% |
| kenneth klette jonassen | kenneth klette jonassen | 12 | 3.09% | 1 | 3.57% |
| neal cardwell | neal cardwell | 11 | 2.84% | 1 | 3.57% |
| eric dumazet | eric dumazet | 5 | 1.29% | 1 | 3.57% |
| david s. miller | david s. miller | 1 | 0.26% | 1 | 3.57% |
| Total | 388 | 100.00% | 28 | 100.00% |
/* Shift newly-SACKed bytes from this skb to the immediately previous
* already-SACKed sk_buff. Mark the newly-SACKed bytes as such.
*/
static bool tcp_shifted_skb(struct sock *sk, struct sk_buff *skb,
struct tcp_sacktag_state *state,
unsigned int pcount, int shifted, int mss,
bool dup_sack)
{
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *prev = tcp_write_queue_prev(sk, skb);
u32 start_seq = TCP_SKB_CB(skb)->seq; /* start of newly-SACKed */
u32 end_seq = start_seq + shifted; /* end of newly-SACKed */
BUG_ON(!pcount);
/* Adjust counters and hints for the newly sacked sequence
* range but discard the return value since prev is already
* marked. We must tag the range first because the seq
* advancement below implicitly advances
* tcp_highest_sack_seq() when skb is highest_sack.
*/
tcp_sacktag_one(sk, state, TCP_SKB_CB(skb)->sacked,
start_seq, end_seq, dup_sack, pcount,
&skb->skb_mstamp);
if (skb == tp->lost_skb_hint)
tp->lost_cnt_hint += pcount;
TCP_SKB_CB(prev)->end_seq += shifted;
TCP_SKB_CB(skb)->seq += shifted;
tcp_skb_pcount_add(prev, pcount);
BUG_ON(tcp_skb_pcount(skb) < pcount);
tcp_skb_pcount_add(skb, -pcount);
/* When we're adding to gso_segs == 1, gso_size will be zero,
* in theory this shouldn't be necessary but as long as DSACK
* code can come after this skb later on it's better to keep
* setting gso_size to something.
*/
if (!TCP_SKB_CB(prev)->tcp_gso_size)
TCP_SKB_CB(prev)->tcp_gso_size = mss;
/* CHECKME: To clear or not to clear? Mimics normal skb currently */
if (tcp_skb_pcount(skb) <= 1)
TCP_SKB_CB(skb)->tcp_gso_size = 0;
/* Difference in this won't matter, both ACKed by the same cumul. ACK */
TCP_SKB_CB(prev)->sacked |= (TCP_SKB_CB(skb)->sacked & TCPCB_EVER_RETRANS);
if (skb->len > 0) {
BUG_ON(!tcp_skb_pcount(skb));
NET_INC_STATS(sock_net(sk), LINUX_MIB_SACKSHIFTED);
return false;
}
/* Whole SKB was eaten :-) */
if (skb == tp->retransmit_skb_hint)
tp->retransmit_skb_hint = prev;
if (skb == tp->lost_skb_hint) {
tp->lost_skb_hint = prev;
tp->lost_cnt_hint -= tcp_skb_pcount(prev);
}
TCP_SKB_CB(prev)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags;
TCP_SKB_CB(prev)->eor = TCP_SKB_CB(skb)->eor;
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
TCP_SKB_CB(prev)->end_seq++;
if (skb == tcp_highest_sack(sk))
tcp_advance_highest_sack(sk, skb);
tcp_skb_collapse_tstamp(prev, skb);
tcp_unlink_write_queue(skb, sk);
sk_wmem_free_skb(sk, skb);
NET_INC_STATS(sock_net(sk), LINUX_MIB_SACKMERGED);
return true;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 270 | 68.70% | 6 | 31.58% |
| neal cardwell | neal cardwell | 56 | 14.25% | 3 | 15.79% |
| eric dumazet | eric dumazet | 44 | 11.20% | 7 | 36.84% |
| martin kafai lau | martin kafai lau | 20 | 5.09% | 2 | 10.53% |
| yuchung cheng | yuchung cheng | 3 | 0.76% | 1 | 5.26% |
| Total | 393 | 100.00% | 19 | 100.00% |
/* I wish gso_size would have a bit more sane initialization than
* something-or-zero which complicates things
*/
static int tcp_skb_seglen(const struct sk_buff *skb)
{
return tcp_skb_pcount(skb) == 1 ? skb->len : tcp_skb_mss(skb);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 28 | 96.55% | 2 | 66.67% |
| eric dumazet | eric dumazet | 1 | 3.45% | 1 | 33.33% |
| Total | 29 | 100.00% | 3 | 100.00% |
/* Shifting pages past head area doesn't work */
static int skb_can_shift(const struct sk_buff *skb)
{
return !skb_headlen(skb) && skb_is_nonlinear(skb);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 23 | 95.83% | 1 | 50.00% |
| eric dumazet | eric dumazet | 1 | 4.17% | 1 | 50.00% |
| Total | 24 | 100.00% | 2 | 100.00% |
/* Try collapsing SACK blocks spanning across multiple skbs to a single
* skb.
*/
static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
struct tcp_sacktag_state *state,
u32 start_seq, u32 end_seq,
bool dup_sack)
{
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *prev;
int mss;
int pcount = 0;
int len;
int in_sack;
if (!sk_can_gso(sk))
goto fallback;
/* Normally R but no L won't result in plain S */
if (!dup_sack &&
(TCP_SKB_CB(skb)->sacked & (TCPCB_LOST|TCPCB_SACKED_RETRANS)) == TCPCB_SACKED_RETRANS)
goto fallback;
if (!skb_can_shift(skb))
goto fallback;
/* This frame is about to be dropped (was ACKed). */
if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una))
goto fallback;
/* Can only happen with delayed DSACK + discard craziness */
if (unlikely(skb == tcp_write_queue_head(sk)))
goto fallback;
prev = tcp_write_queue_prev(sk, skb);
if ((TCP_SKB_CB(prev)->sacked & TCPCB_TAGBITS) != TCPCB_SACKED_ACKED)
goto fallback;
if (!tcp_skb_can_collapse_to(prev))
goto fallback;
in_sack = !after(start_seq, TCP_SKB_CB(skb)->seq) &&
!before(end_seq, TCP_SKB_CB(skb)->end_seq);
if (in_sack) {
len = skb->len;
pcount = tcp_skb_pcount(skb);
mss = tcp_skb_seglen(skb);
/* TODO: Fix DSACKs to not fragment already SACKed and we can
* drop this restriction as unnecessary
*/
if (mss != tcp_skb_seglen(prev))
goto fallback;
} else {
if (!after(TCP_SKB_CB(skb)->end_seq, start_seq))
goto noop;
/* CHECKME: This is non-MSS split case only?, this will
* cause skipped skbs due to advancing loop btw, original
* has that feature too
*/
if (tcp_skb_pcount(skb) <= 1)
goto noop;
in_sack = !after(start_seq, TCP_SKB_CB(skb)->seq);
if (!in_sack) {
/* TODO: head merge to next could be attempted here
* if (!after(TCP_SKB_CB(skb)->end_seq, end_seq)),
* though it might not be worth of the additional hassle
*
* ...we can probably just fallback to what was done
* previously. We could try merging non-SACKed ones
* as well but it probably isn't going to buy off
* because later SACKs might again split them, and
* it would make skb timestamp tracking considerably
* harder problem.
*/
goto fallback;
}
len = end_seq - TCP_SKB_CB(skb)->seq;
BUG_ON(len < 0);
BUG_ON(len > skb->len);
/* MSS boundaries should be honoured or else pcount will
* severely break even though it makes things bit trickier.
* Optimize common case to avoid most of the divides
*/
mss = tcp_skb_mss(skb);
/* TODO: Fix DSACKs to not fragment already SACKed and we can
* drop this restriction as unnecessary
*/
if (mss != tcp_skb_seglen(prev))
goto fallback;
if (len == mss) {
pcount = 1;
} else if (len < mss) {
goto noop;
} else {
pcount = len / mss;
len = pcount * mss;
}
}
/* tcp_sacktag_one() won't SACK-tag ranges below snd_una */
if (!after(TCP_SKB_CB(skb)->seq + len, tp->snd_una))
goto fallback;
if (!skb_shift(prev, skb, len))
goto fallback;
if (!tcp_shifted_skb(sk, skb, state, pcount, len, mss, dup_sack))
goto out;
/* Hole filled allows collapsing with the next as well, this is very
* useful when hole on every nth skb pattern happens
*/
if (prev == tcp_write_queue_tail(sk))
goto out;
skb = tcp_write_queue_next(sk, prev);
if (!skb_can_shift(skb) ||
(skb == tcp_send_head(sk)) ||
((TCP_SKB_CB(skb)->sacked & TCPCB_TAGBITS) != TCPCB_SACKED_ACKED) ||
(mss != tcp_skb_seglen(skb)))
goto out;
len = skb->len;
if (skb_shift(prev, skb, len)) {
pcount += tcp_skb_pcount(skb);
tcp_shifted_skb(sk, skb, state, tcp_skb_pcount(skb), len, mss, 0);
}
out:
state->fack_count += pcount;
return prev;
noop:
return skb;
fallback:
NET_INC_STATS(sock_net(sk), LINUX_MIB_SACKSHIFTFALLBACK);
return NULL;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 553 | 91.86% | 10 | 62.50% |
| neal cardwell | neal cardwell | 23 | 3.82% | 1 | 6.25% |
| martin kafai lau | martin kafai lau | 11 | 1.83% | 1 | 6.25% |
| stephen hemminger | stephen hemminger | 10 | 1.66% | 1 | 6.25% |
| baruch even | baruch even | 3 | 0.50% | 1 | 6.25% |
| eric dumazet | eric dumazet | 2 | 0.33% | 2 | 12.50% |
| Total | 602 | 100.00% | 16 | 100.00% |
static struct sk_buff *tcp_sacktag_walk(struct sk_buff *skb, struct sock *sk,
struct tcp_sack_block *next_dup,
struct tcp_sacktag_state *state,
u32 start_seq, u32 end_seq,
bool dup_sack_in)
{
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *tmp;
tcp_for_write_queue_from(skb, sk) {
int in_sack = 0;
bool dup_sack = dup_sack_in;
if (skb == tcp_send_head(sk))
break;
/* queue is in-order => we can short-circuit the walk early */
if (!before(TCP_SKB_CB(skb)->seq, end_seq))
break;
if (next_dup &&
before(TCP_SKB_CB(skb)->seq, next_dup->end_seq)) {
in_sack = tcp_match_skb_to_sack(sk, skb,
next_dup->start_seq,
next_dup->end_seq);
if (in_sack > 0)
dup_sack = true;
}
/* skb reference here is a bit tricky to get right, since
* shifting can eat and free both this skb and the next,
* so not even _safe variant of the loop is enough.
*/
if (in_sack <= 0) {
tmp = tcp_shift_skb_data(sk, skb, state,
start_seq, end_seq, dup_sack);
if (tmp) {
if (tmp != skb) {
skb = tmp;
continue;
}
in_sack = 0;
} else {
in_sack = tcp_match_skb_to_sack(sk, skb,
start_seq,
end_seq);
}
}
if (unlikely(in_sack < 0))
break;
if (in_sack) {
TCP_SKB_CB(skb)->sacked =
tcp_sacktag_one(sk,
state,
TCP_SKB_CB(skb)->sacked,
TCP_SKB_CB(skb)->seq,
TCP_SKB_CB(skb)->end_seq,
dup_sack,
tcp_skb_pcount(skb),
&skb->skb_mstamp);
if (!before(TCP_SKB_CB(skb)->seq,
tcp_highest_sack_seq(tp)))
tcp_advance_highest_sack(sk, skb);
}
state->fack_count += tcp_skb_pcount(skb);
}
return skb;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 280 | 90.61% | 5 | 55.56% |
| neal cardwell | neal cardwell | 21 | 6.80% | 1 | 11.11% |
| eric dumazet | eric dumazet | 5 | 1.62% | 2 | 22.22% |
| yuchung cheng | yuchung cheng | 3 | 0.97% | 1 | 11.11% |
| Total | 309 | 100.00% | 9 | 100.00% |
/* Avoid all extra work that is being done by sacktag while walking in
* a normal way
*/
static struct sk_buff *tcp_sacktag_skip(struct sk_buff *skb, struct sock *sk,
struct tcp_sacktag_state *state,
u32 skip_to_seq)
{
tcp_for_write_queue_from(skb, sk) {
if (skb == tcp_send_head(sk))
break;
if (after(TCP_SKB_CB(skb)->end_seq, skip_to_seq))
break;
state->fack_count += tcp_skb_pcount(skb);
}
return skb;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 71 | 100.00% | 4 | 100.00% |
| Total | 71 | 100.00% | 4 | 100.00% |
static struct sk_buff *tcp_maybe_skipping_dsack(struct sk_buff *skb,
struct sock *sk,
struct tcp_sack_block *next_dup,
struct tcp_sacktag_state *state,
u32 skip_to_seq)
{
if (!next_dup)
return skb;
if (before(next_dup->start_seq, skip_to_seq)) {
skb = tcp_sacktag_skip(skb, sk, state, next_dup->start_seq);
skb = tcp_sacktag_walk(skb, sk, NULL, state,
next_dup->start_seq, next_dup->end_seq,
1);
}
return skb;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 92 | 98.92% | 3 | 75.00% |
| ian morris | ian morris | 1 | 1.08% | 1 | 25.00% |
| Total | 93 | 100.00% | 4 | 100.00% |
static int tcp_sack_cache_ok(const struct tcp_sock *tp, const struct tcp_sack_block *cache)
{
return cache < tp->recv_sack_cache + ARRAY_SIZE(tp->recv_sack_cache);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 30 | 93.75% | 1 | 50.00% |
| eric dumazet | eric dumazet | 2 | 6.25% | 1 | 50.00% |
| Total | 32 | 100.00% | 2 | 100.00% |
static int
tcp_sacktag_write_queue(struct sock *sk, const struct sk_buff *ack_skb,
u32 prior_snd_una, struct tcp_sacktag_state *state)
{
struct tcp_sock *tp = tcp_sk(sk);
const unsigned char *ptr = (skb_transport_header(ack_skb) +
TCP_SKB_CB(ack_skb)->sacked);
struct tcp_sack_block_wire *sp_wire = (struct tcp_sack_block_wire *)(ptr+2);
struct tcp_sack_block sp[TCP_NUM_SACKS];
struct tcp_sack_block *cache;
struct sk_buff *skb;
int num_sacks = min(TCP_NUM_SACKS, (ptr[1] - TCPOLEN_SACK_BASE) >> 3);
int used_sacks;
bool found_dup_sack = false;
int i, j;
int first_sack_index;
state->flag = 0;
state->reord = tp->packets_out;
if (!tp->sacked_out) {
if (WARN_ON(tp->fackets_out))
tp->fackets_out = 0;
tcp_highest_sack_reset(sk);
}
found_dup_sack = tcp_check_dsack(sk, ack_skb, sp_wire,
num_sacks, prior_snd_una);
if (found_dup_sack)
state->flag |= FLAG_DSACKING_ACK;
/* Eliminate too old ACKs, but take into
* account more or less fresh ones, they can
* contain valid SACK info.
*/
if (before(TCP_SKB_CB(ack_skb)->ack_seq, prior_snd_una - tp->max_window))
return 0;
if (!tp->packets_out)
goto out;
used_sacks = 0;
first_sack_index = 0;
for (i = 0; i < num_sacks; i++) {
bool dup_sack = !i && found_dup_sack;
sp[used_sacks].start_seq = get_unaligned_be32(&sp_wire[i].start_seq);
sp[used_sacks].end_seq = get_unaligned_be32(&sp_wire[i].end_seq);
if (!tcp_is_sackblock_valid(tp, dup_sack,
sp[used_sacks].start_seq,
sp[used_sacks].end_seq)) {
int mib_idx;
if (dup_sack) {
if (!tp->undo_marker)
mib_idx = LINUX_MIB_TCPDSACKIGNOREDNOUNDO;
else
mib_idx = LINUX_MIB_TCPDSACKIGNOREDOLD;
} else {
/* Don't count olds caused by ACK reordering */
if ((TCP_SKB_CB(ack_skb)->ack_seq != tp->snd_una) &&
!after(sp[used_sacks].end_seq, tp->snd_una))
continue;
mib_idx = LINUX_MIB_TCPSACKDISCARD;
}
NET_INC_STATS(sock_net(sk), mib_idx);
if (i == 0)
first_sack_index = -1;
continue;
}
/* Ignore very old stuff early */
if (!after(sp[used_sacks].end_seq, prior_snd_una))
continue;
used_sacks++;
}
/* order SACK blocks to allow in order walk of the retrans queue */
for (i = used_sacks - 1; i > 0; i--) {
for (j = 0; j < i; j++) {
if (after(sp[j].start_seq, sp[j + 1].start_seq)) {
swap(sp[j], sp[j + 1]);
/* Track where the first SACK block goes to */
if (j == first_sack_index)
first_sack_index = j + 1;
}
}
}
skb = tcp_write_queue_head(sk);
state->fack_count = 0;
i = 0;
if (!tp->sacked_out) {
/* It's already past, so skip checking against it */
cache = tp->recv_sack_cache + ARRAY_SIZE(tp->recv_sack_cache);
} else {
cache = tp->recv_sack_cache;
/* Skip empty blocks in at head of the cache */
while (tcp_sack_cache_ok(tp, cache) && !cache->start_seq &&
!cache->end_seq)
cache++;
}
while (i < used_sacks) {
u32 start_seq = sp[i].start_seq;
u32 end_seq = sp[i].end_seq;
bool dup_sack = (found_dup_sack && (i == first_sack_index));
struct tcp_sack_block *next_dup = NULL;
if (found_dup_sack && ((i + 1) == first_sack_index))
next_dup = &sp[i + 1];
/* Skip too early cached blocks */
while (tcp_sack_cache_ok(tp, cache) &&
!before(start_seq, cache->end_seq))
cache++;
/* Can skip some work by looking recv_sack_cache? */
if (tcp_sack_cache_ok(tp, cache) && !dup_sack &&
after(end_seq, cache->start_seq)) {
/* Head todo? */
if (before(start_seq, cache->start_seq)) {
skb = tcp_sacktag_skip(skb, sk, state,
start_seq);
skb = tcp_sacktag_walk(skb, sk, next_dup,
state,
start_seq,
cache->start_seq,
dup_sack);
}
/* Rest of the block already fully processed? */
if (!after(end_seq, cache->end_seq))
goto advance_sp;
skb = tcp_maybe_skipping_dsack(skb, sk, next_dup,
state,
cache->end_seq);
/* ...tail remains todo... */
if (tcp_highest_sack_seq(tp) == cache->end_seq) {
/* ...but better entrypoint exists! */
skb = tcp_highest_sack(sk);
if (!skb)
break;
state->fack_count = tp->fackets_out;
cache++;
goto walk;
}
skb = tcp_sacktag_skip(skb, sk, state, cache->end_seq);
/* Check overlap against next cached too (past this one already) */
cache++;
continue;
}
if (!before(start_seq, tcp_highest_sack_seq(tp))) {
skb = tcp_highest_sack(sk);
if (!skb)
break;
state->fack_count = tp->fackets_out;
}
skb = tcp_sacktag_skip(skb, sk, state, start_seq);
walk:
skb = tcp_sacktag_walk(skb, sk, next_dup, state,
start_seq, end_seq, dup_sack);
advance_sp:
i++;
}
/* Clear the head of the cache sack blocks so we can skip it next time */
for (i = 0; i < ARRAY_SIZE(tp->recv_sack_cache) - used_sacks; i++) {
tp->recv_sack_cache[i].start_seq = 0;
tp->recv_sack_cache[i].end_seq = 0;
}
for (j = 0; j < used_sacks; j++)
tp->recv_sack_cache[i++] = sp[j];
if ((state->reord < tp->fackets_out) &&
((inet_csk(sk)->icsk_ca_state != TCP_CA_Loss) || tp->undo_marker))
tcp_update_reordering(sk, tp->fackets_out - state->reord, 0);
tcp_verify_left_out(tp);
out:
#if FASTRETRANS_DEBUG > 0
WARN_ON((int)tp->sacked_out < 0);
WARN_ON((int)tp->lost_out < 0);
WARN_ON((int)tp->retrans_out < 0);
WARN_ON((int)tcp_packets_in_flight(tp) < 0);
#endif
return state->flag;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 911 | 82.97% | 16 | 39.02% |
| pre-git | pre-git | 98 | 8.93% | 6 | 14.63% |
| pavel emelianov | pavel emelianov | 19 | 1.73% | 3 | 7.32% |
| baruch even | baruch even | 15 | 1.37% | 1 | 2.44% |
| kenneth klette jonassen | kenneth klette jonassen | 12 | 1.09% | 1 | 2.44% |
| yuchung cheng | yuchung cheng | 11 | 1.00% | 3 | 7.32% |
| david s. miller | david s. miller | 9 | 0.82% | 3 | 7.32% |
| eric dumazet | eric dumazet | 7 | 0.64% | 3 | 7.32% |
| adam langley | adam langley | 6 | 0.55% | 1 | 2.44% |
| stephen hemminger | stephen hemminger | 4 | 0.36% | 1 | 2.44% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 2 | 0.18% | 1 | 2.44% |
| harvey harrison | harvey harrison | 2 | 0.18% | 1 | 2.44% |
| ian morris | ian morris | 2 | 0.18% | 1 | 2.44% |
| Total | 1098 | 100.00% | 41 | 100.00% |
/* Limits sacked_out so that sum with lost_out isn't ever larger than
* packets_out. Returns false if sacked_out adjustement wasn't necessary.
*/
static bool tcp_limit_reno_sacked(struct tcp_sock *tp)
{
u32 holes;
holes = max(tp->lost_out, 1U);
holes = min(holes, tp->packets_out);
if ((tp->sacked_out + holes) > tp->packets_out) {
tp->sacked_out = tp->packets_out - holes;
return true;
}
return false;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 65 | 95.59% | 3 | 75.00% |
| eric dumazet | eric dumazet | 3 | 4.41% | 1 | 25.00% |
| Total | 68 | 100.00% | 4 | 100.00% |
/* If we receive more dupacks than we expected counting segments
* in assumption of absent reordering, interpret this as reordering.
* The only another reason could be bug in receiver TCP.
*/
static void tcp_check_reno_reordering(struct sock *sk, const int addend)
{
struct tcp_sock *tp = tcp_sk(sk);
if (tcp_limit_reno_sacked(tp))
tcp_update_reordering(sk, tp->packets_out + addend, 0);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 45 | 100.00% | 2 | 100.00% |
| Total | 45 | 100.00% | 2 | 100.00% |
/* Emulate SACKs for SACKless connection: account for a new dupack. */
static void tcp_add_reno_sack(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
u32 prior_sacked = tp->sacked_out;
tp->sacked_out++;
tcp_check_reno_reordering(sk, 0);
if (tp->sacked_out > prior_sacked)
tp->delivered++; /* Some out-of-order packet is delivered */
tcp_verify_left_out(tp);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 38 | 64.41% | 2 | 66.67% |
| yuchung cheng | yuchung cheng | 21 | 35.59% | 1 | 33.33% |
| Total | 59 | 100.00% | 3 | 100.00% |
/* Account for ACK, ACKing some data in Reno Recovery phase. */
static void tcp_remove_reno_sacks(struct sock *sk, int acked)
{
struct tcp_sock *tp = tcp_sk(sk);
if (acked > 0) {
/* One ACK acked hole. The rest eat duplicate ACKs. */
tp->delivered += max_t(int, acked - tp->sacked_out, 1);
if (acked - 1 >= tp->sacked_out)
tp->sacked_out = 0;
else
tp->sacked_out -= acked - 1;
}
tcp_check_reno_reordering(sk, acked);
tcp_verify_left_out(tp);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 70 | 80.46% | 2 | 66.67% |
| yuchung cheng | yuchung cheng | 17 | 19.54% | 1 | 33.33% |
| Total | 87 | 100.00% | 3 | 100.00% |
static inline void tcp_reset_reno_sack(struct tcp_sock *tp)
{
tp->sacked_out = 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 18 | 100.00% | 1 | 100.00% |
| Total | 18 | 100.00% | 1 | 100.00% |
void tcp_clear_retrans(struct tcp_sock *tp)
{
tp->retrans_out = 0;
tp->lost_out = 0;
tp->undo_marker = 0;
tp->undo_retrans = -1;
tp->fackets_out = 0;
tp->sacked_out = 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 40 | 85.11% | 3 | 75.00% |
| ilpo jarvinen | ilpo jarvinen | 7 | 14.89% | 1 | 25.00% |
| Total | 47 | 100.00% | 4 | 100.00% |
static inline void tcp_init_undo(struct tcp_sock *tp)
{
tp->undo_marker = tp->snd_una;
/* Retransmission still in flight may cause DSACKs later. */
tp->undo_retrans = tp->retrans_out ? : -1;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 32 | 96.97% | 2 | 66.67% |
| ilpo jarvinen | ilpo jarvinen | 1 | 3.03% | 1 | 33.33% |
| Total | 33 | 100.00% | 3 | 100.00% |
/* Enter Loss state. If we detect SACK reneging, forget all SACK information
* and reset tags completely, otherwise preserve SACKs. If receiver
* dropped its ofo queue, we will know this due to reneging detection.
*/
void tcp_enter_loss(struct sock *sk)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
struct net *net = sock_net(sk);
struct sk_buff *skb;
bool new_recovery = icsk->icsk_ca_state < TCP_CA_Recovery;
bool is_reneg; /* is receiver reneging on SACKs? */
/* Reduce ssthresh if it has not yet been made inside this window. */
if (icsk->icsk_ca_state <= TCP_CA_Disorder ||
!after(tp->high_seq, tp->snd_una) ||
(icsk->icsk_ca_state == TCP_CA_Loss && !icsk->icsk_retransmits)) {
tp->prior_ssthresh = tcp_current_ssthresh(sk);
tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk);
tcp_ca_event(sk, CA_EVENT_LOSS);
tcp_init_undo(tp);
}
tp->snd_cwnd = 1;
tp->snd_cwnd_cnt = 0;
tp->snd_cwnd_stamp = tcp_time_stamp;
tp->retrans_out = 0;
tp->lost_out = 0;
if (tcp_is_reno(tp))
tcp_reset_reno_sack(tp);
skb = tcp_write_queue_head(sk);
is_reneg = skb && (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED);
if (is_reneg) {
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSACKRENEGING);
tp->sacked_out = 0;
tp->fackets_out = 0;
}
tcp_clear_all_retrans_hints(tp);
tcp_for_write_queue(skb, sk) {
if (skb == tcp_send_head(sk))
break;
TCP_SKB_CB(skb)->sacked &= (~TCPCB_TAGBITS)|TCPCB_SACKED_ACKED;
if (!(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED) || is_reneg) {
TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_ACKED;
TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
tp->lost_out += tcp_skb_pcount(skb);
tp->retransmit_high = TCP_SKB_CB(skb)->end_seq;
}
}
tcp_verify_left_out(tp);
/* Timeout in disordered state after receiving substantial DUPACKs
* suggests that the degree of reordering is over-estimated.
*/
if (icsk->icsk_ca_state <= TCP_CA_Disorder &&
tp->sacked_out >= net->ipv4.sysctl_tcp_reordering)
tp->reordering = min_t(unsigned int, tp->reordering,
net->ipv4.sysctl_tcp_reordering);
tcp_set_ca_state(sk, TCP_CA_Loss);
tp->high_seq = tp->snd_nxt;
tcp_ecn_queue_cwr(tp);
/* F-RTO RFC5682 sec 3.1 step 1: retransmit SND.UNA if no previous
* loss recovery is underway except recurring timeout(s) on
* the same SND.UNA (sec 3.2). Disable F-RTO on path MTU probing
*/
tp->frto = sysctl_tcp_frto &&
(new_recovery || icsk->icsk_retransmits) &&
!inet_csk(sk)->icsk_mtup.probe_size;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 203 | 51.13% | 5 | 20.00% |
| ilpo jarvinen | ilpo jarvinen | 89 | 22.42% | 11 | 44.00% |
| pasi sarolahti | pasi sarolahti | 37 | 9.32% | 1 | 4.00% |
| neal cardwell | neal cardwell | 37 | 9.32% | 1 | 4.00% |
| nikolay borisov | nikolay borisov | 15 | 3.78% | 1 | 4.00% |
| david s. miller | david s. miller | 14 | 3.53% | 4 | 16.00% |
| eric dumazet | eric dumazet | 1 | 0.25% | 1 | 4.00% |
| florian westphal | florian westphal | 1 | 0.25% | 1 | 4.00% |
| Total | 397 | 100.00% | 25 | 100.00% |
/* If ACK arrived pointing to a remembered SACK, it means that our
* remembered SACKs do not reflect real state of receiver i.e.
* receiver _host_ is heavily congested (or buggy).
*
* To avoid big spurious retransmission bursts due to transient SACK
* scoreboard oddities that look like reneging, we give the receiver a
* little time (max(RTT/2, 10ms)) to send us some more ACKs that will
* restore sanity to the SACK scoreboard. If the apparent reneging
* persists until this RTO then we'll clear the SACK scoreboard.
*/
static bool tcp_check_sack_reneging(struct sock *sk, int flag)
{
if (flag & FLAG_SACK_RENEGING) {
struct tcp_sock *tp = tcp_sk(sk);
unsigned long delay = max(usecs_to_jiffies(tp->srtt_us >> 4),
msecs_to_jiffies(10));
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
delay, TCP_RTO_MAX);
return true;
}
return false;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 29 | 41.43% | 1 | 12.50% |
| neal cardwell | neal cardwell | 18 | 25.71% | 1 | 12.50% |
| pasi sarolahti | pasi sarolahti | 15 | 21.43% | 1 | 12.50% |
| ilpo jarvinen | ilpo jarvinen | 7 | 10.00% | 4 | 50.00% |
| stephen hemminger | stephen hemminger | 1 | 1.43% | 1 | 12.50% |
| Total | 70 | 100.00% | 8 | 100.00% |
static inline int tcp_fackets_out(const struct tcp_sock *tp)
{
return tcp_is_reno(tp) ? tp->sacked_out + 1 : tp->fackets_out;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 21 | 72.41% | 1 | 25.00% |
| ilpo jarvinen | ilpo jarvinen | 7 | 24.14% | 2 | 50.00% |
| pasi sarolahti | pasi sarolahti | 1 | 3.45% | 1 | 25.00% |
| Total | 29 | 100.00% | 4 | 100.00% |
/* Heurestics to calculate number of duplicate ACKs. There's no dupACKs
* counter when SACK is enabled (without SACK, sacked_out is used for
* that purpose).
*
* Instead, with FACK TCP uses fackets_out that includes both SACKed
* segments up to the highest received SACK block so far and holes in
* between them.
*
* With reordering, holes may still be in flight, so RFC3517 recovery
* uses pure sacked_out (total number of SACKed segments) even though
* it violates the RFC that uses duplicate ACKs, often these are equal
* but when e.g. out-of-window ACKs or packet duplication occurs,
* they differ. Since neither occurs due to loss, TCP should really
* ignore them.
*/
static inline int tcp_dupack_heuristics(const struct tcp_sock *tp)
{
return tcp_is_fack(tp) ? tp->fackets_out : tp->sacked_out + 1;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 13 | 44.83% | 1 | 20.00% |
| yuchung cheng | yuchung cheng | 11 | 37.93% | 1 | 20.00% |
| pre-git | pre-git | 5 | 17.24% | 3 | 60.00% |
| Total | 29 | 100.00% | 5 | 100.00% |
static bool tcp_pause_early_retransmit(struct sock *sk, int flag)
{
struct tcp_sock *tp = tcp_sk(sk);
unsigned long delay;
/* Delay early retransmit and entering fast recovery for
* max(RTT/4, 2msec) unless ack has ECE mark, no RTT samples
* available, or RTO is scheduled to fire first.
*/
if (sysctl_tcp_early_retrans < 2 || sysctl_tcp_early_retrans > 3 ||
(flag & FLAG_ECE) || !tp->srtt_us)
return false;
delay = max(usecs_to_jiffies(tp->srtt_us >> 5),
msecs_to_jiffies(2));
if (!time_after(inet_csk(sk)->icsk_timeout, (jiffies + delay)))
return false;
inet_csk_reset_xmit_timer(sk, ICSK_TIME_EARLY_RETRANS, delay,
TCP_RTO_MAX);
return true;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 55 | 50.93% | 1 | 10.00% |
| pre-git | pre-git | 32 | 29.63% | 4 | 40.00% |
| eric dumazet | eric dumazet | 12 | 11.11% | 1 | 10.00% |
| david s. miller | david s. miller | 3 | 2.78% | 1 | 10.00% |
| stephen hemminger | stephen hemminger | 3 | 2.78% | 1 | 10.00% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 3 | 2.78% | 2 | 20.00% |
| Total | 108 | 100.00% | 10 | 100.00% |
/* Linux NewReno/SACK/FACK/ECN state machine.
* --------------------------------------
*
* "Open" Normal state, no dubious events, fast path.
* "Disorder" In all the respects it is "Open",
* but requires a bit more attention. It is entered when
* we see some SACKs or dupacks. It is split of "Open"
* mainly to move some processing from fast path to slow one.
* "CWR" CWND was reduced due to some Congestion Notification event.
* It can be ECN, ICMP source quench, local device congestion.
* "Recovery" CWND was reduced, we are fast-retransmitting.
* "Loss" CWND was reduced due to RTO timeout or SACK reneging.
*
* tcp_fastretrans_alert() is entered:
* - each incoming ACK, if state is not "Open"
* - when arrived ACK is unusual, namely:
* * SACK
* * Duplicate ACK.
* * ECN ECE.
*
* Counting packets in flight is pretty simple.
*
* in_flight = packets_out - left_out + retrans_out
*
* packets_out is SND.NXT-SND.UNA counted in packets.
*
* retrans_out is number of retransmitted segments.
*
* left_out is number of segments left network, but not ACKed yet.
*
* left_out = sacked_out + lost_out
*
* sacked_out: Packets, which arrived to receiver out of order
* and hence not ACKed. With SACKs this number is simply
* amount of SACKed data. Even without SACKs
* it is easy to give pretty reliable estimate of this number,
* counting duplicate ACKs.
*
* lost_out: Packets lost by network. TCP has no explicit
* "loss notification" feedback from network (for now).
* It means that this number can be only _guessed_.
* Actually, it is the heuristics to predict lossage that
* distinguishes different algorithms.
*
* F.e. after RTO, when all the queue is considered as lost,
* lost_out = packets_out and in_flight = retrans_out.
*
* Essentially, we have now two algorithms counting
* lost packets.
*
* FACK: It is the simplest heuristics. As soon as we decided
* that something is lost, we decide that _all_ not SACKed
* packets until the most forward SACK are lost. I.e.
* lost_out = fackets_out - sacked_out and left_out = fackets_out.
* It is absolutely correct estimate, if network does not reorder
* packets. And it loses any connection to reality when reordering
* takes place. We use FACK by default until reordering
* is suspected on the path to this destination.
*
* NewReno: when Recovery is entered, we assume that one segment
* is lost (classic Reno). While we are in Recovery and
* a partial ACK arrives, we assume that one more packet
* is lost (NewReno). This heuristics are the same in NewReno
* and SACK.
*
* Imagine, that's all! Forget about all this shamanism about CWND inflation
* deflation etc. CWND is real congestion window, never inflated, changes
* only according to classic VJ rules.
*
* Really tricky (and requiring careful tuning) part of algorithm
* is hidden in functions tcp_time_to_recover() and tcp_xmit_retransmit_queue().
* The first determines the moment _when_ we should reduce CWND and,
* hence, slow down forward transmission. In fact, it determines the moment
* when we decide that hole is caused by loss, rather than by a reorder.
*
* tcp_xmit_retransmit_queue() decides, _what_ we should retransmit to fill
* holes, caused by lost packets.
*
* And the most logically complicated part of algorithm is undo
* heuristics. We detect false retransmits due to both too early
* fast retransmit (reordering) and underestimated RTO, analyzing
* timestamps and D-SACKs. When we detect that some segments were
* retransmitted by mistake and CWND reduction was wrong, we undo
* window reduction and abort recovery phase. This logic is hidden
* inside several functions named tcp_try_undo_<something>.
*/
/* This function decides, when we should leave Disordered state
* and enter Recovery phase, reducing congestion window.
*
* Main question: may we further continue forward transmission
* with the same cwnd?
*/
static bool tcp_time_to_recover(struct sock *sk, int flag)
{
struct tcp_sock *tp = tcp_sk(sk);
__u32 packets_out;
int tcp_reordering = sock_net(sk)->ipv4.sysctl_tcp_reordering;
/* Trick#1: The loss is proven. */
if (tp->lost_out)
return true;
/* Not-A-Trick#2 : Classic rule... */
if (tcp_dupack_heuristics(tp) > tp->reordering)
return true;
/* Trick#4: It is still not OK... But will it be useful to delay
* recovery more?
*/
packets_out = tp->packets_out;
if (packets_out <= tp->reordering &&
tp->sacked_out >= max_t(__u32, packets_out/2, tcp_reordering) &&
!tcp_may_send_now(sk)) {
/* We have nothing to send. This connection is limited
* either by receiver window or by application.
*/
return true;
}
/* If a thin stream is detected, retransmit after first
* received dupack. Employ only if SACK is supported in order
* to avoid possible corner-case series of spurious retransmissions
* Use only if there are no unsent data.
*/
if ((tp->thin_dupack || sysctl_tcp_thin_dupack) &&
tcp_stream_is_thin(tp) && tcp_dupack_heuristics(tp) > 1 &&
tcp_is_sack(tp) && !tcp_send_head(sk))
return true;
/* Trick#6: TCP early retransmit, per RFC5827. To avoid spurious
* retransmissions due to small network reorderings, we implement
* Mitigation A.3 in the RFC and delay the retransmission for a short
* interval if appropriate.
*/
if (tp->do_early_retrans && !tp->retrans_out && tp->sacked_out &&
(tp->packets_out >= (tp->sacked_out + 1) && tp->packets_out < 4) &&
!tcp_may_send_now(sk))
return !tcp_pause_early_retransmit(sk, flag);
return false;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 132 | 67.01% | 1 | 10.00% |
| pre-git | pre-git | 32 | 16.24% | 3 | 30.00% |
| ilpo jarvinen | ilpo jarvinen | 13 | 6.60% | 2 | 20.00% |
| nikolay borisov | nikolay borisov | 13 | 6.60% | 1 | 10.00% |
| david s. miller | david s. miller | 6 | 3.05% | 2 | 20.00% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 1 | 0.51% | 1 | 10.00% |
| Total | 197 | 100.00% | 10 | 100.00% |
/* Detect loss in event "A" above by marking head of queue up as lost.
* For FACK or non-SACK(Reno) senders, the first "packets" number of segments
* are considered lost. For RFC3517 SACK, a segment is considered lost if it
* has at least tp->reordering SACKed seqments above it; "packets" refers to
* the maximum SACKed segments to pass before reaching this limit.
*/
static void tcp_mark_head_lost(struct sock *sk, int packets, int mark_head)
{
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb;
int cnt, oldcnt, lost;
unsigned int mss;
/* Use SACK to deduce losses of new sequences sent during recovery */
const u32 loss_high = tcp_is_sack(tp) ? tp->snd_nxt : tp->high_seq;
WARN_ON(packets > tp->packets_out);
if (tp->lost_skb_hint) {
skb = tp->lost_skb_hint;
cnt = tp->lost_cnt_hint;
/* Head already handled? */
if (mark_head && skb != tcp_write_queue_head(sk))
return;
} else {
skb = tcp_write_queue_head(sk);
cnt = 0;
}
tcp_for_write_queue_from(skb, sk) {
if (skb == tcp_send_head(sk))
break;
/* TODO: do this better */
/* this is not the most efficient way to do this... */
tp->lost_skb_hint = skb;
tp->lost_cnt_hint = cnt;
if (after(TCP_SKB_CB(skb)->end_seq, loss_high))
break;
oldcnt = cnt;
if (tcp_is_fack(tp) || tcp_is_reno(tp) ||
(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))
cnt += tcp_skb_pcount(skb);
if (cnt > packets) {
if ((tcp_is_sack(tp) && !tcp_is_fack(tp)) ||
(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) ||
(oldcnt >= packets))
break;
mss = tcp_skb_mss(skb);
/* If needed, chop off the prefix to mark as lost. */
lost = (packets - oldcnt) * mss;
if (lost < skb->len &&
tcp_fragment(sk, skb, lost, mss, GFP_ATOMIC) < 0)
break;
cnt = packets;
}
tcp_skb_mark_lost(tp, skb);
if (mark_head)
break;
}
tcp_verify_left_out(tp);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 273 | 90.40% | 2 | 28.57% |
| neal cardwell | neal cardwell | 20 | 6.62% | 1 | 14.29% |
| linus torvalds | linus torvalds | 4 | 1.32% | 1 | 14.29% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 2 | 0.66% | 1 | 14.29% |
| octavian purdila | octavian purdila | 2 | 0.66% | 1 | 14.29% |
| eric dumazet | eric dumazet | 1 | 0.33% | 1 | 14.29% |
| Total | 302 | 100.00% | 7 | 100.00% |
/* Account newly detected lost packet(s) */
static void tcp_update_scoreboard(struct sock *sk, int fast_rexmit)
{
struct tcp_sock *tp = tcp_sk(sk);
if (tcp_is_reno(tp)) {
tcp_mark_head_lost(sk, 1, 1);
} else if (tcp_is_fack(tp)) {
int lost = tp->fackets_out - tp->reordering;
if (lost <= 0)
lost = 1;
tcp_mark_head_lost(sk, lost, 0);
} else {
int sacked_upto = tp->sacked_out - tp->reordering;
if (sacked_upto >= 0)
tcp_mark_head_lost(sk, sacked_upto, 0);
else if (fast_rexmit)
tcp_mark_head_lost(sk, 1, 1);
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 75 | 60.00% | 1 | 9.09% |
| linus torvalds | linus torvalds | 20 | 16.00% | 2 | 18.18% |
| pre-git | pre-git | 13 | 10.40% | 3 | 27.27% |
| ilpo jarvinen | ilpo jarvinen | 12 | 9.60% | 2 | 18.18% |
| david s. miller | david s. miller | 3 | 2.40% | 1 | 9.09% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 2 | 1.60% | 2 | 18.18% |
| Total | 125 | 100.00% | 11 | 100.00% |
static bool tcp_tsopt_ecr_before(const struct tcp_sock *tp, u32 when)
{
return tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
before(tp->rx_opt.rcv_tsecr, when);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 39 | 100.00% | 4 | 100.00% |
| Total | 39 | 100.00% | 4 | 100.00% |
/* skb is spurious retransmitted if the returned timestamp echo
* reply is prior to the skb transmission time
*/
static bool tcp_skb_spurious_retrans(const struct tcp_sock *tp,
const struct sk_buff *skb)
{
return (TCP_SKB_CB(skb)->sacked & TCPCB_RETRANS) &&
tcp_tsopt_ecr_before(tp, tcp_skb_timestamp(skb));
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 40 | 100.00% | 1 | 100.00% |
| Total | 40 | 100.00% | 1 | 100.00% |
/* Nothing was retransmitted or returned timestamp is less
* than timestamp of the first retransmission.
*/
static inline bool tcp_packet_delayed(const struct tcp_sock *tp)
{
return !tp->retrans_stamp ||
tcp_tsopt_ecr_before(tp, tp->retrans_stamp);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 26 | 92.86% | 3 | 75.00% |
| pre-git | pre-git | 2 | 7.14% | 1 | 25.00% |
| Total | 28 | 100.00% | 4 | 100.00% |
/* Undo procedures. */
/* We can clear retrans_stamp when there are no retransmissions in the
* window. It would seem that it is trivially available for us in
* tp->retrans_out, however, that kind of assumptions doesn't consider
* what will happen if errors occur when sending retransmission for the
* second time. ...It could the that such segment has only
* TCPCB_EVER_RETRANS set at the present time. It seems that checking
* the head skb is enough except for some reneging corner cases that
* are not worth the effort.
*
* Main reason for all this complexity is the fact that connection dying
* time now depends on the validity of the retrans_stamp, in particular,
* that successive retransmissions of a segment must not advance
* retrans_stamp under any conditions.
*/
static bool tcp_any_retrans_done(const struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb;
if (tp->retrans_out)
return true;
skb = tcp_write_queue_head(sk);
if (unlikely(skb && TCP_SKB_CB(skb)->sacked & TCPCB_EVER_RETRANS))
return true;
return false;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| marcelo ricardo leitner | marcelo ricardo leitner | 66 | 100.00% | 1 | 100.00% |
| Total | 66 | 100.00% | 1 | 100.00% |
#if FASTRETRANS_DEBUG > 1
static void DBGUNDO(struct sock *sk, const char *msg)
{
struct tcp_sock *tp = tcp_sk(sk);
struct inet_sock *inet = inet_sk(sk);
if (sk->sk_family == AF_INET) {
pr_debug("Undo %s %pI4/%u c%u l%u ss%u/%u p%u\n",
msg,
&inet->inet_daddr, ntohs(inet->inet_dport),
tp->snd_cwnd, tcp_left_out(tp),
tp->snd_ssthresh, tp->prior_ssthresh,
tp->packets_out);
}
#if IS_ENABLED(CONFIG_IPV6)
else if (sk->sk_family == AF_INET6) {
pr_debug("Undo %s %pI6/%u c%u l%u ss%u/%u p%u\n",
msg,
&sk->sk_v6_daddr, ntohs(inet->inet_dport),
tp->snd_cwnd, tcp_left_out(tp),
tp->snd_ssthresh, tp->prior_ssthresh,
tp->packets_out);
}
#endif
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 92 | 63.45% | 1 | 33.33% |
| ilpo jarvinen | ilpo jarvinen | 51 | 35.17% | 1 | 33.33% |
| eric dumazet | eric dumazet | 2 | 1.38% | 1 | 33.33% |
| Total | 145 | 100.00% | 3 | 100.00% |
#else
#define DBGUNDO(x...) do { } while (0)
#endif
static void tcp_undo_cwnd_reduction(struct sock *sk, bool unmark_loss)
{
struct tcp_sock *tp = tcp_sk(sk);
if (unmark_loss) {
struct sk_buff *skb;
tcp_for_write_queue(skb, sk) {
if (skb == tcp_send_head(sk))
break;
TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
}
tp->lost_out = 0;
tcp_clear_all_retrans_hints(tp);
}
if (tp->prior_ssthresh) {
const struct inet_connection_sock *icsk = inet_csk(sk);
if (icsk->icsk_ca_ops->undo_cwnd)
tp->snd_cwnd = icsk->icsk_ca_ops->undo_cwnd(sk);
else
tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh << 1);
if (tp->prior_ssthresh > tp->snd_ssthresh) {
tp->snd_ssthresh = tp->prior_ssthresh;
tcp_ecn_withdraw_cwr(tp);
}
}
tp->snd_cwnd_stamp = tcp_time_stamp;
tp->undo_marker = 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 123 | 72.78% | 3 | 30.00% |
| pre-git | pre-git | 17 | 10.06% | 3 | 30.00% |
| stephen hemminger | stephen hemminger | 16 | 9.47% | 1 | 10.00% |
| ilpo jarvinen | ilpo jarvinen | 12 | 7.10% | 2 | 20.00% |
| florian westphal | florian westphal | 1 | 0.59% | 1 | 10.00% |
| Total | 169 | 100.00% | 10 | 100.00% |
static inline bool tcp_may_undo(const struct tcp_sock *tp)
{
return tp->undo_marker && (!tp->undo_retrans || tcp_packet_delayed(tp));
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 28 | 93.33% | 1 | 50.00% |
| pre-git | pre-git | 2 | 6.67% | 1 | 50.00% |
| Total | 30 | 100.00% | 2 | 100.00% |
/* People celebrate: "We love our President!" */
static bool tcp_try_undo_recovery(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
if (tcp_may_undo(tp)) {
int mib_idx;
/* Happy end! We did not retransmit anything
* or our original transmission succeeded.
*/
DBGUNDO(sk, inet_csk(sk)->icsk_ca_state == TCP_CA_Loss ? "loss" : "retrans");
tcp_undo_cwnd_reduction(sk, false);
if (inet_csk(sk)->icsk_ca_state == TCP_CA_Loss)
mib_idx = LINUX_MIB_TCPLOSSUNDO;
else
mib_idx = LINUX_MIB_TCPFULLUNDO;
NET_INC_STATS(sock_net(sk), mib_idx);
}
if (tp->snd_una == tp->high_seq && tcp_is_reno(tp)) {
/* Hold old state until something *above* high_seq
* is ACKed. For Reno it is MUST to prevent false
* fast retransmits (RFC2582). SACK TCP is safe. */
if (!tcp_any_retrans_done(sk))
tp->retrans_stamp = 0;
return true;
}
tcp_set_ca_state(sk, TCP_CA_Open);
return false;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 91 | 67.91% | 3 | 25.00% |
| marcelo ricardo leitner | marcelo ricardo leitner | 14 | 10.45% | 1 | 8.33% |
| ilpo jarvinen | ilpo jarvinen | 10 | 7.46% | 2 | 16.67% |
| david s. miller | david s. miller | 6 | 4.48% | 1 | 8.33% |
| stephen hemminger | stephen hemminger | 6 | 4.48% | 1 | 8.33% |
| pre-git | pre-git | 4 | 2.99% | 2 | 16.67% |
| linus torvalds | linus torvalds | 2 | 1.49% | 1 | 8.33% |
| eric dumazet | eric dumazet | 1 | 0.75% | 1 | 8.33% |
| Total | 134 | 100.00% | 12 | 100.00% |
/* Try to undo cwnd reduction, because D-SACKs acked all retransmitted data */
static bool tcp_try_undo_dsack(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
if (tp->undo_marker && !tp->undo_retrans) {
DBGUNDO(sk, "D-SACK");
tcp_undo_cwnd_reduction(sk, false);
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPDSACKUNDO);
return true;
}
return false;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| pre-git | pre-git | 24 | 37.50% | 4 | 33.33% |
| yuchung cheng | yuchung cheng | 23 | 35.94% | 3 | 25.00% |
| ilpo jarvinen | ilpo jarvinen | 14 | 21.88% | 2 | 16.67% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 1 | 1.56% | 1 | 8.33% |
| linus torvalds | linus torvalds | 1 | 1.56% | 1 | 8.33% |
| eric dumazet | eric dumazet | 1 | 1.56% | 1 | 8.33% |
| Total | 64 | 100.00% | 12 | 100.00% |
/* Undo during loss recovery after partial ACK or using F-RTO. */
static bool tcp_try_undo_loss(struct sock *sk, bool frto_undo)
{
struct tcp_sock *tp = tcp_sk(sk);
if (frto_undo || tcp_may_undo(tp)) {
tcp_undo_cwnd_reduction(sk, true);
DBGUNDO(sk, "partial loss");
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSSUNDO);
if (frto_undo)
NET_INC_STATS(sock_net(sk),
LINUX_MIB_TCPSPURIOUSRTOS);
inet_csk(sk)->icsk_retransmits = 0;
if (frto_undo || tcp_is_sack(tp))
tcp_set_ca_state(sk, TCP_CA_Open);
return true;
}
return false;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 66 | 63.46% | 3 | 30.00% |
| hideaki yoshifuji | hideaki yoshifuji | 15 | 14.42% | 1 | 10.00% |
| ilpo jarvinen | ilpo jarvinen | 10 | 9.62% | 2 | 20.00% |
| pre-git | pre-git | 10 | 9.62% | 2 | 20.00% |
| eric dumazet | eric dumazet | 2 | 1.92% | 1 | 10.00% |
| david s. miller | david s. miller | 1 | 0.96% | 1 | 10.00% |
| Total | 104 | 100.00% | 10 | 100.00% |
/* The cwnd reduction in CWR and Recovery uses the PRR algorithm in RFC 6937.
* It computes the number of packets to send (sndcnt) based on packets newly
* delivered:
* 1) If the packets in flight is larger than ssthresh, PRR spreads the
* cwnd reductions across a full RTT.
* 2) Otherwise PRR uses packet conservation to send as much as delivered.
* But when the retransmits are acked without further losses, PRR
* slow starts cwnd up to ssthresh to speed up the recovery.
*/
static void tcp_init_cwnd_reduction(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
tp->high_seq = tp->snd_nxt;
tp->tlp_high_seq = 0;
tp->snd_cwnd_cnt = 0;
tp->prior_cwnd = tp->snd_cwnd;
tp->prr_delivered = 0;
tp->prr_out = 0;
tp->snd_ssthresh = inet_csk(sk)->icsk_ca_ops->ssthresh(sk);
tcp_ecn_queue_cwr(tp);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 30 | 36.59% | 1 | 8.33% |
| pre-git | pre-git | 28 | 34.15% | 6 | 50.00% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 12 | 14.63% | 1 | 8.33% |
| linus torvalds | linus torvalds | 6 | 7.32% | 1 | 8.33% |
| stephen hemminger | stephen hemminger | 5 | 6.10% | 2 | 16.67% |
| florian westphal | florian westphal | 1 | 1.22% | 1 | 8.33% |
| Total | 82 | 100.00% | 12 | 100.00% |
static void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked,
int flag)
{
struct tcp_sock *tp = tcp_sk(sk);
int sndcnt = 0;
int delta = tp->snd_ssthresh - tcp_packets_in_flight(tp);
if (newly_acked_sacked <= 0 || WARN_ON_ONCE(!tp->prior_cwnd))
return;
tp->prr_delivered += newly_acked_sacked;
if (delta < 0) {
u64 dividend = (u64)tp->snd_ssthresh * tp->prr_delivered +
tp->prior_cwnd - 1;
sndcnt = div_u64(dividend, tp->prior_cwnd) - tp->prr_out;
} else if ((flag & FLAG_RETRANS_DATA_ACKED) &&
!(flag & FLAG_LOST_RETRANS)) {
sndcnt = min_t(int, delta,
max_t(int, tp->prr_delivered - tp->prr_out,
newly_acked_sacked) + 1);
} else {
sndcnt = min(delta, newly_acked_sacked);
}
/* Force a fast retransmit upon entering fast recovery */
sndcnt = max(sndcnt, (tp->prr_out ? 0 : 1));
tp->snd_cwnd = tcp_packets_in_flight(tp) + sndcnt;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 145 | 75.13% | 4 | 33.33% |
| pre-git | pre-git | 31 | 16.06% | 3 | 25.00% |
| ilpo jarvinen | ilpo jarvinen | 8 | 4.15% | 1 | 8.33% |
| pavel emelianov | pavel emelianov | 5 | 2.59% | 2 | 16.67% |
| david s. miller | david s. miller | 3 | 1.55% | 1 | 8.33% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 1 | 0.52% | 1 | 8.33% |
| Total | 193 | 100.00% | 12 | 100.00% |
static inline void tcp_end_cwnd_reduction(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
/* Reset cwnd to ssthresh in CWR or Recovery (unless it's undone) */
if (inet_csk(sk)->icsk_ca_state == TCP_CA_CWR ||
(tp->undo_marker && tp->snd_ssthresh < TCP_INFINITE_SSTHRESH)) {
tp->snd_cwnd = tp->snd_ssthresh;
tp->snd_cwnd_stamp = tcp_time_stamp;
}
tcp_ca_event(sk, CA_EVENT_COMPLETE_CWR);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 30 | 43.48% | 1 | 11.11% |
| pre-git | pre-git | 27 | 39.13% | 5 | 55.56% |
| ilpo jarvinen | ilpo jarvinen | 8 | 11.59% | 1 | 11.11% |
| pavel emelianov | pavel emelianov | 3 | 4.35% | 1 | 11.11% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 1 | 1.45% | 1 | 11.11% |
| Total | 69 | 100.00% | 9 | 100.00% |
/* Enter CWR state. Disable cwnd undo since congestion is proven with ECN */
void tcp_enter_cwr(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
tp->prior_ssthresh = 0;
if (inet_csk(sk)->icsk_ca_state < TCP_CA_CWR) {
tp->undo_marker = 0;
tcp_init_cwnd_reduction(sk);
tcp_set_ca_state(sk, TCP_CA_CWR);
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ilpo jarvinen | ilpo jarvinen | 29 | 50.88% | 1 | 50.00% |
| yuchung cheng | yuchung cheng | 28 | 49.12% | 1 | 50.00% |
| Total | 57 | 100.00% | 2 | 100.00% |
EXPORT_SYMBOL(tcp_enter_cwr);
static void tcp_try_keep_open(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
int state = TCP_CA_Open;
if (tcp_left_out(tp) || tcp_any_retrans_done(sk))
state = TCP_CA_Disorder;
if (inet_csk(sk)->icsk_ca_state != state) {
tcp_set_ca_state(sk, state);
tp->high_seq = tp->snd_nxt;
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| pre-git | pre-git | 27 | 38.57% | 4 | 44.44% |
| yuchung cheng | yuchung cheng | 25 | 35.71% | 1 | 11.11% |
| ilpo jarvinen | ilpo jarvinen | 14 | 20.00% | 2 | 22.22% |
| pavel emelianov | pavel emelianov | 3 | 4.29% | 1 | 11.11% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 1 | 1.43% | 1 | 11.11% |
| Total | 70 | 100.00% | 9 | 100.00% |
static void tcp_try_to_open(struct sock *sk, int flag)
{
struct tcp_sock *tp = tcp_sk(sk);
tcp_verify_left_out(tp);
if (!tcp_any_retrans_done(sk))
tp->retrans_stamp = 0;
if (flag & FLAG_ECE)
tcp_enter_cwr(sk);
if (inet_csk(sk)->icsk_ca_state != TCP_CA_CWR) {
tcp_try_keep_open(sk);
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 38 | 52.78% | 1 | 14.29% |
| pre-git | pre-git | 17 | 23.61% | 2 | 28.57% |
| ilpo jarvinen | ilpo jarvinen | 8 | 11.11% | 1 | 14.29% |
| david s. miller | david s. miller | 5 | 6.94% | 1 | 14.29% |
| stephen hemminger | stephen hemminger | 3 | 4.17% | 1 | 14.29% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 1 | 1.39% | 1 | 14.29% |
| Total | 72 | 100.00% | 7 | 100.00% |
static void tcp_mtup_probe_failed(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
icsk->icsk_mtup.search_high = icsk->icsk_mtup.probe_size - 1;
icsk->icsk_mtup.probe_size = 0;
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMTUPFAIL);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 31 | 58.49% | 1 | 14.29% |
| rick jones | rick jones | 9 | 16.98% | 1 | 14.29% |
| pre-git | pre-git | 8 | 15.09% | 3 | 42.86% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 4 | 7.55% | 1 | 14.29% |
| eric dumazet | eric dumazet | 1 | 1.89% | 1 | 14.29% |
| Total | 53 | 100.00% | 7 | 100.00% |
static void tcp_mtup_probe_success(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
struct inet_connection_sock *icsk = inet_csk(sk);
/* FIXME: breaks with very large cwnd */
tp->prior_ssthresh = tcp_current_ssthresh(sk);
tp->snd_cwnd = tp->snd_cwnd *
tcp_mss_to_mtu(sk, tp->mss_cache) /
icsk->icsk_mtup.probe_size;
tp->snd_cwnd_cnt = 0;
tp->snd_cwnd_stamp = tcp_time_stamp;
tp->snd_ssthresh = tcp_current_ssthresh(sk);
icsk->icsk_mtup.search_low = icsk->icsk_mtup.probe_size;
icsk->icsk_mtup.probe_size = 0;
tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMTUPSUCCESS);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 111 | 89.52% | 3 | 50.00% |
| rick jones | rick jones | 9 | 7.26% | 1 | 16.67% |
| nandita dukkipati | nandita dukkipati | 3 | 2.42% | 1 | 16.67% |
| eric dumazet | eric dumazet | 1 | 0.81% | 1 | 16.67% |
| Total | 124 | 100.00% | 6 | 100.00% |
/* Do a simple retransmit without using the backoff mechanisms in
* tcp_timer. This is used for path mtu discovery.
* The socket is already locked here.
*/
void tcp_simple_retransmit(struct sock *sk)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb;
unsigned int mss = tcp_current_mss(sk);
u32 prior_lost = tp->lost_out;
tcp_for_write_queue(skb, sk) {
if (skb == tcp_send_head(sk))
break;
if (tcp_skb_seglen(skb) > mss &&
!(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) {
if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) {
TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
tp->retrans_out -= tcp_skb_pcount(skb);
}
tcp_skb_mark_lost_uncond_verify(tp, skb);
}
}
tcp_clear_retrans_hints_partial(tp);
if (prior_lost == tp->lost_out)
return;
if (tcp_is_reno(tp))
tcp_limit_reno_sacked(tp);
tcp_verify_left_out(tp);
/* Don't muck with the congestion window here.
* Reason is that we do not increase amount of _data_
* in network, but units changed and effective
* cwnd/ssthresh really reduced now.
*/
if (icsk->icsk_ca_state != TCP_CA_Loss) {
tp->high_seq = tp->snd_nxt;
tp->snd_ssthresh = tcp_current_ssthresh(sk);
tp->prior_ssthresh = 0;
tp->undo_marker = 0;
tcp_set_ca_state(sk, TCP_CA_Loss);
}
tcp_xmit_retransmit_queue(sk);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 193 | 89.77% | 5 | 45.45% |
| pre-git | pre-git | 10 | 4.65% | 3 | 27.27% |
| nandita dukkipati | nandita dukkipati | 4 | 1.86% | 1 | 9.09% |
| stephen hemminger | stephen hemminger | 4 | 1.86% | 1 | 9.09% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 4 | 1.86% | 1 | 9.09% |
| Total | 215 | 100.00% | 11 | 100.00% |
EXPORT_SYMBOL(tcp_simple_retransmit);
static void tcp_enter_recovery(struct sock *sk, bool ece_ack)
{
struct tcp_sock *tp = tcp_sk(sk);
int mib_idx;
if (tcp_is_reno(tp))
mib_idx = LINUX_MIB_TCPRENORECOVERY;
else
mib_idx = LINUX_MIB_TCPSACKRECOVERY;
NET_INC_STATS(sock_net(sk), mib_idx);
tp->prior_ssthresh = 0;
tcp_init_undo(tp);
if (!tcp_in_cwnd_reduction(sk)) {
if (!ece_ack)
tp->prior_ssthresh = tcp_current_ssthresh(sk);
tcp_init_cwnd_reduction(sk);
}
tcp_set_ca_state(sk, TCP_CA_Recovery);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 99 | 99.00% | 5 | 83.33% |
| eric dumazet | eric dumazet | 1 | 1.00% | 1 | 16.67% |
| Total | 100 | 100.00% | 6 | 100.00% |
/* Process an ACK in CA_Loss state. Move to CA_Open if lost data are
* recovered or spurious. Otherwise retransmits more on partial ACKs.
*/
static void tcp_process_loss(struct sock *sk, int flag, bool is_dupack,
int *rexmit)
{
struct tcp_sock *tp = tcp_sk(sk);
bool recovered = !before(tp->snd_una, tp->high_seq);
if ((flag & FLAG_SND_UNA_ADVANCED) &&
tcp_try_undo_loss(sk, false))
return;
if (tp->frto) { /* F-RTO RFC5682 sec 3.1 (sack enhanced version). */
/* Step 3.b. A timeout is spurious if not all data are
* lost, i.e., never-retransmitted data are (s)acked.
*/
if ((flag & FLAG_ORIG_SACK_ACKED) &&
tcp_try_undo_loss(sk, true))
return;
if (after(tp->snd_nxt, tp->high_seq)) {
if (flag & FLAG_DATA_SACKED || is_dupack)
tp->frto = 0; /* Step 3.a. loss was real */
} else if (flag & FLAG_SND_UNA_ADVANCED && !recovered) {
tp->high_seq = tp->snd_nxt;
/* Step 2.b. Try send new data (but deferred until cwnd
* is updated in tcp_ack()). Otherwise fall back to
* the conventional recovery.
*/
if (tcp_send_head(sk) &&
after(tcp_wnd_end(tp), tp->snd_nxt)) {
*rexmit = REXMIT_NEW;
return;
}
tp->frto = 0;
}
}
if (recovered) {
/* F-RTO RFC5682 sec 3.1 step 2.a and 1st part of step 3.a */
tcp_try_undo_recovery(sk);
return;
}
if (tcp_is_reno(tp)) {
/* A Reno DUPACK means new data in F-RTO step 2.b above are
* delivered. Lower inflight to clock out (re)tranmissions.
*/
if (after(tp->snd_nxt, tp->high_seq) && is_dupack)
tcp_add_reno_sack(sk);
else if (flag & FLAG_SND_UNA_ADVANCED)
tcp_reset_reno_sack(tp);
}
*rexmit = REXMIT_LOST;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 232 | 100.00% | 6 | 100.00% |
| Total | 232 | 100.00% | 6 | 100.00% |
/* Undo during fast recovery after partial ACK. */
static bool tcp_try_undo_partial(struct sock *sk, const int acked)
{
struct tcp_sock *tp = tcp_sk(sk);
if (tp->undo_marker && tcp_packet_delayed(tp)) {
/* Plain luck! Hole if filled with delayed
* packet, rather than with a retransmit.
*/
tcp_update_reordering(sk, tcp_fackets_out(tp) + acked, 1);
/* We are getting evidence that the reordering degree is higher
* than we realized. If there are no retransmits out then we
* can undo. Otherwise we clock out new packets but do not
* mark more packets lost or retransmit more.
*/
if (tp->retrans_out)
return true;
if (!tcp_any_retrans_done(sk))
tp->retrans_stamp = 0;
DBGUNDO(sk, "partial recovery");
tcp_undo_cwnd_reduction(sk, true);
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPPARTIALUNDO);
tcp_try_keep_open(sk);
return true;
}
return false;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 111 | 99.11% | 2 | 66.67% |
| eric dumazet | eric dumazet | 1 | 0.89% | 1 | 33.33% |
| Total | 112 | 100.00% | 3 | 100.00% |
/* Process an event, which can update packets-in-flight not trivially.
* Main goal of this function is to calculate new estimate for left_out,
* taking into account both packets sitting in receiver's buffer and
* packets lost by network.
*
* Besides that it updates the congestion state when packet loss or ECN
* is detected. But it does not reduce the cwnd, it is done by the
* congestion control later.
*
* It does _not_ decide what to send, it is made in function
* tcp_xmit_retransmit_queue().
*/
static void tcp_fastretrans_alert(struct sock *sk, const int acked,
bool is_dupack, int *ack_flag, int *rexmit)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
int fast_rexmit = 0, flag = *ack_flag;
bool do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) &&
(tcp_fackets_out(tp) > tp->reordering));
if (WARN_ON(!tp->packets_out && tp->sacked_out))
tp->sacked_out = 0;
if (WARN_ON(!tp->sacked_out && tp->fackets_out))
tp->fackets_out = 0;
/* Now state machine starts.
* A. ECE, hence prohibit cwnd undoing, the reduction is required. */
if (flag & FLAG_ECE)
tp->prior_ssthresh = 0;
/* B. In all the states check for reneging SACKs. */
if (tcp_check_sack_reneging(sk, flag))
return;
/* C. Check consistency of the current state. */
tcp_verify_left_out(tp);
/* D. Check state exit conditions. State can be terminated
* when high_seq is ACKed. */
if (icsk->icsk_ca_state == TCP_CA_Open) {
WARN_ON(tp->retrans_out != 0);
tp->retrans_stamp = 0;
} else if (!before(tp->snd_una, tp->high_seq)) {
switch (icsk->icsk_ca_state) {
case TCP_CA_CWR:
/* CWR is to be held something *above* high_seq
* is ACKed for CWR bit to reach receiver. */
if (tp->snd_una != tp->high_seq) {
tcp_end_cwnd_reduction(sk);
tcp_set_ca_state(sk, TCP_CA_Open);
}
break;
case TCP_CA_Recovery:
if (tcp_is_reno(tp))
tcp_reset_reno_sack(tp);
if (tcp_try_undo_recovery(sk))
return;
tcp_end_cwnd_reduction(sk);
break;
}
}
/* Use RACK to detect loss */
if (sysctl_tcp_recovery & TCP_RACK_LOST_RETRANS &&
tcp_rack_mark_lost(sk)) {
flag |= FLAG_LOST_RETRANS;
*ack_flag |= FLAG_LOST_RETRANS;
}
/* E. Process state. */
switch (icsk->icsk_ca_state) {
case TCP_CA_Recovery:
if (!(flag & FLAG_SND_UNA_ADVANCED)) {
if (tcp_is_reno(tp) && is_dupack)
tcp_add_reno_sack(sk);
} else {
if (tcp_try_undo_partial(sk, acked))
return;
/* Partial ACK arrived. Force fast retransmit. */
do_lost = tcp_is_reno(tp) ||
tcp_fackets_out(tp) > tp->reordering;
}
if (tcp_try_undo_dsack(sk)) {
tcp_try_keep_open(sk);
return;
}
break;
case TCP_CA_Loss:
tcp_process_loss(sk, flag, is_dupack, rexmit);
if (icsk->icsk_ca_state != TCP_CA_Open &&
!(flag & FLAG_LOST_RETRANS))
return;
/* Change state if cwnd is undone or retransmits are lost */
default:
if (tcp_is_reno(tp)) {
if (flag & FLAG_SND_UNA_ADVANCED)
tcp_reset_reno_sack(tp);
if (is_dupack)
tcp_add_reno_sack(sk);
}
if (icsk->icsk_ca_state <= TCP_CA_Disorder)
tcp_try_undo_dsack(sk);
if (!tcp_time_to_recover(sk, flag)) {
tcp_try_to_open(sk, flag);
return;
}
/* MTU probe failure: don't reduce cwnd */
if (icsk->icsk_ca_state < TCP_CA_CWR &&
icsk->icsk_mtup.probe_size &&
tp->snd_una == tp->mtu_probe.probe_seq_start) {
tcp_mtup_probe_failed(sk);
/* Restores the reduction we did in tcp_mtup_probe() */
tp->snd_cwnd++;
tcp_simple_retransmit(sk);
return;
}
/* Otherwise enter Recovery state */
tcp_enter_recovery(sk, (flag & FLAG_ECE));
fast_rexmit = 1;
}
if (do_lost)
tcp_update_scoreboard(sk, fast_rexmit);
*rexmit = REXMIT_LOST;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 368 | 68.79% | 12 | 40.00% |
| ilpo jarvinen | ilpo jarvinen | 103 | 19.25% | 6 | 20.00% |
| john heffner | john heffner | 28 | 5.23% | 1 | 3.33% |
| pre-git | pre-git | 23 | 4.30% | 7 | 23.33% |
| neal cardwell | neal cardwell | 6 | 1.12% | 1 | 3.33% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 3 | 0.56% | 1 | 3.33% |
| david s. miller | david s. miller | 2 | 0.37% | 1 | 3.33% |
| eric dumazet | eric dumazet | 2 | 0.37% | 1 | 3.33% |
| Total | 535 | 100.00% | 30 | 100.00% |
/* Kathleen Nichols' algorithm for tracking the minimum value of
* a data stream over some fixed time interval. (E.g., the minimum
* RTT over the past five minutes.) It uses constant space and constant
* time per update yet almost always delivers the same minimum as an
* implementation that has to keep all the data in the window.
*
* The algorithm keeps track of the best, 2nd best & 3rd best min
* values, maintaining an invariant that the measurement time of the
* n'th best >= n-1'th best. It also makes sure that the three values
* are widely separated in the time window since that bounds the worse
* case error when that data is monotonically increasing over the window.
*
* Upon getting a new min, we can forget everything earlier because it
* has no value - the new min is <= everything else in the window by
* definition and it's the most recent. So we restart fresh on every new min
* and overwrites 2nd & 3rd choices. The same property holds for 2nd & 3rd
* best.
*/
static void tcp_update_rtt_min(struct sock *sk, u32 rtt_us)
{
const u32 now = tcp_time_stamp, wlen = sysctl_tcp_min_rtt_wlen * HZ;
struct rtt_meas *m = tcp_sk(sk)->rtt_min;
struct rtt_meas rttm = {
.rtt = likely(rtt_us) ? rtt_us : jiffies_to_usecs(1),
.ts = now,
};
u32 elapsed;
/* Check if the new measurement updates the 1st, 2nd, or 3rd choices */
if (unlikely(rttm.rtt <= m[0].rtt))
m[0] = m[1] = m[2] = rttm;
else if (rttm.rtt <= m[1].rtt)
m[1] = m[2] = rttm;
else if (rttm.rtt <= m[2].rtt)
m[2] = rttm;
elapsed = now - m[0].ts;
if (unlikely(elapsed > wlen)) {
/* Passed entire window without a new min so make 2nd choice
* the new min & 3rd choice the new 2nd. So forth and so on.
*/
m[0] = m[1];
m[1] = m[2];
m[2] = rttm;
if (now - m[0].ts > wlen) {
m[0] = m[1];
m[1] = rttm;
if (now - m[0].ts > wlen)
m[0] = rttm;
}
} else if (m[1].ts == m[0].ts && elapsed > wlen / 4) {
/* Passed a quarter of the window without a new min so
* take 2nd choice from the 2nd quarter of the window.
*/
m[2] = m[1] = rttm;
} else if (m[2].ts == m[1].ts && elapsed > wlen / 2) {
/* Passed half the window without a new min so take the 3rd
* choice from the last half of the window.
*/
m[2] = rttm;
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 313 | 97.51% | 1 | 50.00% |
| eric dumazet | eric dumazet | 8 | 2.49% | 1 | 50.00% |
| Total | 321 | 100.00% | 2 | 100.00% |
static inline bool tcp_ack_update_rtt(struct sock *sk, const int flag,
long seq_rtt_us, long sack_rtt_us,
long ca_rtt_us)
{
const struct tcp_sock *tp = tcp_sk(sk);
/* Prefer RTT measured from ACK's timing to TS-ECR. This is because
* broken middle-boxes or peers may corrupt TS-ECR fields. But
* Karn's algorithm forbids taking RTT if some retransmitted data
* is acked (RFC6298).
*/
if (seq_rtt_us < 0)
seq_rtt_us = sack_rtt_us;
/* RTTM Rule: A TSecr value received in a segment is used to
* update the averaged RTT measurement only if the segment
* acknowledges some new data, i.e., only if it advances the
* left edge of the send window.
* See draft-ietf-tcplw-high-performance-00, section 3.3.
*/
if (seq_rtt_us < 0 && tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
flag & FLAG_ACKED)
seq_rtt_us = ca_rtt_us = jiffies_to_usecs(tcp_time_stamp -
tp->rx_opt.rcv_tsecr);
if (seq_rtt_us < 0)
return false;
/* ca_rtt_us >= 0 is counting on the invariant that ca_rtt_us is
* always taken together with ACK, SACK, or TS-opts. Any negative
* values will be skipped with the seq_rtt_us < 0 check above.
*/
tcp_update_rtt_min(sk, ca_rtt_us);
tcp_rtt_estimator(sk, seq_rtt_us);
tcp_set_rto(sk);
/* RFC6298: only reset backoff on valid RTT measurement. */
inet_csk(sk)->icsk_backoff = 0;
return true;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 76 | 59.84% | 5 | 27.78% |
| pre-git | pre-git | 27 | 21.26% | 6 | 33.33% |
| eric dumazet | eric dumazet | 14 | 11.02% | 1 | 5.56% |
| ilpo jarvinen | ilpo jarvinen | 4 | 3.15% | 2 | 11.11% |
| david s. miller | david s. miller | 3 | 2.36% | 1 | 5.56% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 2 | 1.57% | 2 | 11.11% |
| nandita dukkipati | nandita dukkipati | 1 | 0.79% | 1 | 5.56% |
| Total | 127 | 100.00% | 18 | 100.00% |
/* Compute time elapsed between (last) SYNACK and the ACK completing 3WHS. */
void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req)
{
long rtt_us = -1L;
if (req && !req->num_retrans && tcp_rsk(req)->snt_synack.v64) {
struct skb_mstamp now;
skb_mstamp_get(&now);
rtt_us = skb_mstamp_us_delta(&now, &tcp_rsk(req)->snt_synack);
}
tcp_ack_update_rtt(sk, FLAG_SYN_ACKED, rtt_us, -1L, rtt_us);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 76 | 93.83% | 5 | 83.33% |
| eric dumazet | eric dumazet | 5 | 6.17% | 1 | 16.67% |
| Total | 81 | 100.00% | 6 | 100.00% |
static void tcp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
icsk->icsk_ca_ops->cong_avoid(sk, ack, acked);
tcp_sk(sk)->snd_cwnd_stamp = tcp_time_stamp;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 39 | 78.00% | 2 | 25.00% |
| pre-git | pre-git | 8 | 16.00% | 4 | 50.00% |
| linus torvalds | linus torvalds | 2 | 4.00% | 1 | 12.50% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 1 | 2.00% | 1 | 12.50% |
| Total | 50 | 100.00% | 8 | 100.00% |
/* Restart timer after forward progress on connection.
* RFC2988 recommends to restart timer to now+rto.
*/
void tcp_rearm_rto(struct sock *sk)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
/* If the retrans timer is currently being used by Fast Open
* for SYN-ACK retrans purpose, stay put.
*/
if (tp->fastopen_rsk)
return;
if (!tp->packets_out) {
inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
} else {
u32 rto = inet_csk(sk)->icsk_rto;
/* Offset the time elapsed after installing regular RTO */
if (icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS ||
icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) {
struct sk_buff *skb = tcp_write_queue_head(sk);
const u32 rto_time_stamp =
tcp_skb_timestamp(skb) + rto;
s32 delta = (s32)(rto_time_stamp - tcp_time_stamp);
/* delta may not be positive if the socket is locked
* when the retrans timer fires and is rescheduled.
*/
if (delta > 0)
rto = delta;
}
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, rto,
TCP_RTO_MAX);
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 104 | 74.29% | 1 | 11.11% |
| pre-git | pre-git | 29 | 20.71% | 5 | 55.56% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 4 | 2.86% | 1 | 11.11% |
| david s. miller | david s. miller | 2 | 1.43% | 1 | 11.11% |
| eric dumazet | eric dumazet | 1 | 0.71% | 1 | 11.11% |
| Total | 140 | 100.00% | 9 | 100.00% |
/* This function is called when the delayed ER timer fires. TCP enters
* fast recovery and performs fast-retransmit.
*/
void tcp_resume_early_retransmit(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
tcp_rearm_rto(sk);
/* Stop if ER is disabled after the delayed ER timer is scheduled */
if (!tp->do_early_retrans)
return;
tcp_enter_recovery(sk, false);
tcp_update_scoreboard(sk, 1);
tcp_xmit_retransmit_queue(sk);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 27 | 50.94% | 1 | 14.29% |
| pre-git | pre-git | 20 | 37.74% | 4 | 57.14% |
| ilpo jarvinen | ilpo jarvinen | 5 | 9.43% | 1 | 14.29% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 1 | 1.89% | 1 | 14.29% |
| Total | 53 | 100.00% | 7 | 100.00% |
/* If we get here, the whole TSO packet has not been acked. */
static u32 tcp_tso_acked(struct sock *sk, struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
u32 packets_acked;
BUG_ON(!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una));
packets_acked = tcp_skb_pcount(skb);
if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq))
return 0;
packets_acked -= tcp_skb_pcount(skb);
if (packets_acked) {
BUG_ON(tcp_skb_pcount(skb) == 0);
BUG_ON(!before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq));
}
return packets_acked;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 82 | 66.13% | 1 | 8.33% |
| pre-git | pre-git | 19 | 15.32% | 4 | 33.33% |
| ilpo jarvinen | ilpo jarvinen | 11 | 8.87% | 2 | 16.67% |
| john heffner | john heffner | 7 | 5.65% | 1 | 8.33% |
| linus torvalds | linus torvalds | 2 | 1.61% | 1 | 8.33% |
| pavel emelianov | pavel emelianov | 1 | 0.81% | 1 | 8.33% |
| david s. miller | david s. miller | 1 | 0.81% | 1 | 8.33% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 1 | 0.81% | 1 | 8.33% |
| Total | 124 | 100.00% | 12 | 100.00% |
static void tcp_ack_tstamp(struct sock *sk, struct sk_buff *skb,
u32 prior_snd_una)
{
const struct skb_shared_info *shinfo;
/* Avoid cache line misses to get skb_shinfo() and shinfo->tx_flags */
if (likely(!TCP_SKB_CB(skb)->txstamp_ack))
return;
shinfo = skb_shinfo(skb);
if (!before(shinfo->tskey, prior_snd_una) &&
before(shinfo->tskey, tcp_sk(sk)->snd_una))
__skb_tstamp_tx(skb, NULL, sk, SCM_TSTAMP_ACK);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| eric dumazet | eric dumazet | 70 | 83.33% | 1 | 33.33% |
| martin kafai lau | martin kafai lau | 9 | 10.71% | 1 | 33.33% |
| soheil hassas yeganeh | soheil hassas yeganeh | 5 | 5.95% | 1 | 33.33% |
| Total | 84 | 100.00% | 3 | 100.00% |
/* Remove acknowledged frames from the retransmission queue. If our packet
* is before the ack sequence we can discard it as it's confirmed to have
* arrived at the other end.
*/
static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
u32 prior_snd_una, int *acked,
struct tcp_sacktag_state *sack)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
struct skb_mstamp first_ackt, last_ackt, now;
struct tcp_sock *tp = tcp_sk(sk);
u32 prior_sacked = tp->sacked_out;
u32 reord = tp->packets_out;
bool fully_acked = true;
long sack_rtt_us = -1L;
long seq_rtt_us = -1L;
long ca_rtt_us = -1L;
struct sk_buff *skb;
u32 pkts_acked = 0;
u32 last_in_flight = 0;
bool rtt_update;
int flag = 0;
first_ackt.v64 = 0;
while ((skb = tcp_write_queue_head(sk)) && skb != tcp_send_head(sk)) {
struct tcp_skb_cb *scb = TCP_SKB_CB(skb);
u8 sacked = scb->sacked;
u32 acked_pcount;
tcp_ack_tstamp(sk, skb, prior_snd_una);
/* Determine how many packets and what bytes were acked, tso and else */
if (after(scb->end_seq, tp->snd_una)) {
if (tcp_skb_pcount(skb) == 1 ||
!after(tp->snd_una, scb->seq))
break;
acked_pcount = tcp_tso_acked(sk, skb);
if (!acked_pcount)
break;
fully_acked = false;
} else {
/* Speedup tcp_unlink_write_queue() and next loop */
prefetchw(skb->next);
acked_pcount = tcp_skb_pcount(skb);
}
if (unlikely(sacked & TCPCB_RETRANS)) {
if (sacked & TCPCB_SACKED_RETRANS)
tp->retrans_out -= acked_pcount;
flag |= FLAG_RETRANS_DATA_ACKED;
} else if (!(sacked & TCPCB_SACKED_ACKED)) {
last_ackt = skb->skb_mstamp;
WARN_ON_ONCE(last_ackt.v64 == 0);
if (!first_ackt.v64)
first_ackt = last_ackt;
last_in_flight = TCP_SKB_CB(skb)->tx.in_flight;
reord = min(pkts_acked, reord);
if (!after(scb->end_seq, tp->high_seq))
flag |= FLAG_ORIG_SACK_ACKED;
}
if (sacked & TCPCB_SACKED_ACKED) {
tp->sacked_out -= acked_pcount;
} else if (tcp_is_sack(tp)) {
tp->delivered += acked_pcount;
if (!tcp_skb_spurious_retrans(tp, skb))
tcp_rack_advance(tp, &skb->skb_mstamp, sacked);
}
if (sacked & TCPCB_LOST)
tp->lost_out -= acked_pcount;
tp->packets_out -= acked_pcount;
pkts_acked += acked_pcount;
/* Initial outgoing SYN's get put onto the write_queue
* just like anything else we transmit. It is not
* true data, and if we misinform our callers that
* this ACK acks real data, we will erroneously exit
* connection startup slow start one packet too
* quickly. This is severely frowned upon behavior.
*/
if (likely(!(scb->tcp_flags & TCPHDR_SYN))) {
flag |= FLAG_DATA_ACKED;
} else {
flag |= FLAG_SYN_ACKED;
tp->retrans_stamp = 0;
}
if (!fully_acked)
break;
tcp_unlink_write_queue(skb, sk);
sk_wmem_free_skb(sk, skb);
if (unlikely(skb == tp->retransmit_skb_hint))
tp->retransmit_skb_hint = NULL;
if (unlikely(skb == tp->lost_skb_hint))
tp->lost_skb_hint = NULL;
}
if (likely(between(tp->snd_up, prior_snd_una, tp->snd_una)))
tp->snd_up = tp->snd_una;
if (skb && (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))
flag |= FLAG_SACK_RENEGING;
skb_mstamp_get(&now);
if (likely(first_ackt.v64) && !(flag & FLAG_RETRANS_DATA_ACKED)) {
seq_rtt_us = skb_mstamp_us_delta(&now, &first_ackt);
ca_rtt_us = skb_mstamp_us_delta(&now, &last_ackt);
}
if (sack->first_sackt.v64) {
sack_rtt_us = skb_mstamp_us_delta(&now, &sack->first_sackt);
ca_rtt_us = skb_mstamp_us_delta(&now, &sack->last_sackt);
}
rtt_update = tcp_ack_update_rtt(sk, flag, seq_rtt_us, sack_rtt_us,
ca_rtt_us);
if (flag & FLAG_ACKED) {
tcp_rearm_rto(sk);
if (unlikely(icsk->icsk_mtup.probe_size &&
!after(tp->mtu_probe.probe_seq_end, tp->snd_una))) {
tcp_mtup_probe_success(sk);
}
if (tcp_is_reno(tp)) {
tcp_remove_reno_sacks(sk, pkts_acked);
} else {
int delta;
/* Non-retransmitted hole got filled? That's reordering */
if (reord < prior_fackets)
tcp_update_reordering(sk, tp->fackets_out - reord, 0);
delta = tcp_is_fack(tp) ? pkts_acked :
prior_sacked - tp->sacked_out;
tp->lost_cnt_hint -= min(tp->lost_cnt_hint, delta);
}
tp->fackets_out -= min(pkts_acked, tp->fackets_out);
} else if (skb && rtt_update && sack_rtt_us >= 0 &&
sack_rtt_us > skb_mstamp_us_delta(&now, &skb->skb_mstamp)) {
/* Do not re-arm RTO if the sack RTT is measured from data sent
* after when the head was last (re)transmitted. Otherwise the
* timeout may continue to extend in loss recovery.
*/
tcp_rearm_rto(sk);
}
if (icsk->icsk_ca_ops->pkts_acked) {
struct ack_sample sample = { .pkts_acked = pkts_acked,
.rtt_us = ca_rtt_us,
.in_flight = last_in_flight };
icsk->icsk_ca_ops->pkts_acked(sk, &sample);
}
#if FASTRETRANS_DEBUG > 0
WARN_ON((int)tp->sacked_out < 0);
WARN_ON((int)tp->lost_out < 0);
WARN_ON((int)tp->retrans_out < 0);
if (!tp->packets_out && tcp_is_sack(tp)) {
icsk = inet_csk(sk);
if (tp->lost_out) {
pr_debug("Leak l=%u %d\n",
tp->lost_out, icsk->icsk_ca_state);
tp->lost_out = 0;
}
if (tp->sacked_out) {
pr_debug("Leak s=%u %d\n",
tp->sacked_out, icsk->icsk_ca_state);
tp->sacked_out = 0;
}
if (tp->retrans_out) {
pr_debug("Leak r=%u %d\n",
tp->retrans_out, icsk->icsk_ca_state);
tp->retrans_out = 0;
}
}
#endif
*acked = pkts_acked;
return flag;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 595 | 59.03% | 10 | 22.22% |
| eric dumazet | eric dumazet | 133 | 13.19% | 3 | 6.67% |
| stephen hemminger | stephen hemminger | 95 | 9.42% | 5 | 11.11% |
| kenneth klette jonassen | kenneth klette jonassen | 76 | 7.54% | 3 | 6.67% |
| lawrence brakmo | lawrence brakmo | 41 | 4.07% | 2 | 4.44% |
| pre-git | pre-git | 18 | 1.79% | 8 | 17.78% |
| ilpo jarvinen | ilpo jarvinen | 14 | 1.39% | 5 | 11.11% |
| arnaldo carvalho de melo | arnaldo carvalho de melo | 12 | 1.19% | 4 | 8.89% |
| willem de bruijn | willem de bruijn | 6 | 0.60% | 1 | 2.22% |
| nandita dukkipati | nandita dukkipati | 6 | 0.60% | 1 | 2.22% |
| jerry chu | jerry chu | 5 | 0.50% | 1 | 2.22% |
| herbert xu | herbert xu | 5 | 0.50% | 1 | 2.22% |
| pasi sarolahti | pasi sarolahti | 2 | 0.20% | 1 | 2.22% |
| Total | 1008 | 100.00% | 45 | 100.00% |
static void tcp_ack_probe(struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
struct inet_connection_sock *icsk = inet_csk(sk);
/* Was it a usable window open? */
if (!after(TCP_SKB_CB(tcp_send_head(sk))->end_seq, tcp_wnd_end(tp))) {
icsk->icsk_backoff = 0;
inet_csk_clear_xmit_timer(sk, ICSK_TIME_PROBE0);
/* Socket must be waked up by subsequent tcp_data_snd_check().
* This function is not for random using!
*/
} else {
unsigned long when = tcp_probe0_when(sk, TCP_RTO_MAX);
inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
when, TCP_RTO_MAX);
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 55 | 57.89% | 1 | 16.67% |
| ilpo jarvinen | ilpo jarvinen | 28 | 29.47% | 3 | 50.00% |
| eric dumazet | eric dumazet | 12 | 12.63% | 2 | 33.33% |
| Total | 95 | 100.00% | 6 | 100.00% |
static inline bool tcp_ack_is_dubious(const struct sock *sk, const int flag)
{
return !(flag & FLAG_NOT_DUP) || (flag & FLAG_CA_ALERT) ||
inet_csk(sk)->icsk_ca_state != TCP_CA_Open;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 23 | 57.50% | 1 | 33.33% |
| ilpo jarvinen | ilpo jarvinen | 17 | 42.50% | 2 | 66.67% |
| Total | 40 | 100.00% | 3 | 100.00% |
/* Decide wheather to run the increase function of congestion control. */
static inline bool tcp_may_raise_cwnd(const struct sock *sk, const int flag)
{
/* If reordering is high then always grow cwnd whenever data is
* delivered regardless of its ordering. Otherwise stay conservative
* and only grow cwnd on in-order delivery (RFC5681). A stretched ACK w/
* new SACK or ECE mark may first advance cwnd here and later reduce
* cwnd in tcp_fastretrans_alert() based on more states.
*/
if (tcp_sk(sk)->reordering > sock_net(sk)->ipv4.sysctl_tcp_reordering)
return flag & FLAG_FORWARD_PROGRESS;
return flag & FLAG_DATA_ACKED;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 21 | 45.65% | 3 | 33.33% |
| stephen hemminger | stephen hemminger | 12 | 26.09% | 1 | 11.11% |
| nikolay borisov | nikolay borisov | 7 | 15.22% | 1 | 11.11% |
| ilpo jarvinen | ilpo jarvinen | 4 | 8.70% | 2 | 22.22% |
| adrian bunk | adrian bunk | 1 | 2.17% | 1 | 11.11% |
| eric dumazet | eric dumazet | 1 | 2.17% | 1 | 11.11% |
| Total | 46 | 100.00% | 9 | 100.00% |
/* The "ultimate" congestion control function that aims to replace the rigid
* cwnd increase and decrease control (tcp_cong_avoid,tcp_*cwnd_reduction).
* It's called toward the end of processing an ACK with precise rate
* information. All transmission or retransmission are delayed afterwards.
*/
static void tcp_cong_control(struct sock *sk, u32 ack, u32 acked_sacked,
int flag)
{
if (tcp_in_cwnd_reduction(sk)) {
/* Reduce cwnd if state mandates */
tcp_cwnd_reduction(sk, acked_sacked, flag);
} else if (tcp_may_raise_cwnd(sk, flag)) {
/* Advance cwnd if state allows */
tcp_cong_avoid(sk, ack, acked_sacked);
}
tcp_update_pacing_rate(sk);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 66 | 100.00% | 1 | 100.00% |
| Total | 66 | 100.00% | 1 | 100.00% |
/* Check that window update is acceptable.
* The function assumes that snd_una<=ack<=snd_next.
*/
static inline bool tcp_may_update_window(const struct tcp_sock *tp,
const u32 ack, const u32 ack_seq,
const u32 nwin)
{
return after(ack, tp->snd_una) ||
after(ack_seq, tp->snd_wl1) ||
(ack_seq == tp->snd_wl1 && nwin > tp->snd_wnd);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 42 | 72.41% | 1 | 16.67% |
| ilpo jarvinen | ilpo jarvinen | 15 | 25.86% | 4 | 66.67% |
| stephen hemminger | stephen hemminger | 1 | 1.72% | 1 | 16.67% |
| Total | 58 | 100.00% | 6 | 100.00% |
/* If we update tp->snd_una, also update tp->bytes_acked */
static void tcp_snd_una_update(struct tcp_sock *tp, u32 ack)
{
u32 delta = ack - tp->snd_una;
sock_owned_by_me((struct sock *)tp);
u64_stats_update_begin_raw(&tp->syncp);
tp->bytes_acked += delta;
u64_stats_update_end_raw(&tp->syncp);
tp->snd_una = ack;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| eric dumazet | eric dumazet | 61 | 100.00% | 3 | 100.00% |
| Total | 61 | 100.00% | 3 | 100.00% |
/* If we update tp->rcv_nxt, also update tp->bytes_received */
static void tcp_rcv_nxt_update(struct tcp_sock *tp, u32 seq)
{
u32 delta = seq - tp->rcv_nxt;
sock_owned_by_me((struct sock *)tp);
u64_stats_update_begin_raw(&tp->syncp);
tp->bytes_received += delta;
u64_stats_update_end_raw(&tp->syncp);
tp->rcv_nxt = seq;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| eric dumazet | eric dumazet | 61 | 100.00% | 3 | 100.00% |
| Total | 61 | 100.00% | 3 | 100.00% |
/* Update our send window.
*
* Window update algorithm, described in RFC793/RFC1122 (used in linux-2.2
* and in FreeBSD. NetBSD's one is even worse.) is wrong.
*/
static int tcp_ack_update_window(struct sock *sk, const struct sk_buff *skb, u32 ack,
u32 ack_seq)
{
struct tcp_sock *tp = tcp_sk(sk);
int flag = 0;
u32 nwin = ntohs(tcp_hdr(skb)->window);
if (likely(!tcp_hdr(skb)->syn))
nwin <<= tp->rx_opt.snd_wscale;
if (tcp_may_update_window(tp, ack, ack_seq, nwin)) {
flag |= FLAG_WIN_UPDATE;
tcp_update_wl(tp, ack_seq);
if (tp->snd_wnd != nwin) {
tp->snd_wnd = nwin;
/* Note, it is the only place, where
* fast path is recovered for sending TCP.
*/
tp->pred_flags = 0;
tcp_fast_path_check(sk);
if (tcp_send_head(sk))
tcp_slow_start_after_idle_check(sk);
if (nwin > tp->max_window) {
tp->max_window = nwin;
tcp_sync_mss(sk, inet_csk(sk)->icsk_pmtu_cookie);
}
}
}
tcp_snd_una_update(tp, ack);
return flag;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| yuchung cheng | yuchung cheng | 104 | 59.09% | 1 | 7.14% |
| ilpo jarvinen | ilpo jarvinen | 44 | 25.00% | 9 | 64.29% |
| eric dumazet | eric dumazet | 16 | 9.09% | 2 | 14.29% |
| stephen hemminger | stephen hemminger | 12 | 6.82% | 2 | 14.29% |
| Total | 176 | 100.00% | 14 | 100.00% |
static bool __tcp_oow_rate_limited(struct net *net, int mib_idx,
u32 *last_oow_ack_time)
{
if (*last_oow_ack_time) {
s32 elapsed = (s32)(tcp_time_stamp - *last_oow_ack_time);
if (0 <= elapsed && elapsed < sysctl_tcp_invalid_ratelimit) {
NET_INC_STATS(net, mib_idx);
return true; /* rate-limited: don't send yet! */
}
}
*last_oow_ack_time = tcp_time_stamp;
return false; /* not rate-limited: go ahead, send dupack now! */
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| eric dumazet | eric dumazet | 68 | 97.14% | 2 | 66.67% |
| jason baron | jason baron | 2 | 2.86% | 1 | 33.33% |
| Total | 70 | 100.00% | 3 | 100.00% |
/* Return true if we're currently rate-limiting out-of-window ACKs and
* thus shouldn't send a dupack right now. We rate-limit dupacks in
* response to out-of-window SYNs or ACKs to mitigate ACK loops or DoS
* attacks that send repeated SYNs or ACKs for the same connection. To
* do this, we do not send a duplicate SYNACK or ACK if the remote
* endpoint is sending out-of-window SYNs or pure ACKs at a high rate.
*/
bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
int mib_idx, u32 *last_oow_ack_time)
{
/* Data packets without SYNs are not likely part of an ACK loop. */
if ((TCP_SKB_CB(skb)->seq != TCP_SKB_CB(skb)->end_seq) &&
!tcp_hdr(skb)->syn)
return false;
return __tcp_oow_rate_limited(net, mib_idx, last_oow_ack_time);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| jason baron | jason baron | 63 | 100.00% | 1 | 100.00% |
| Total | 63 | 100.00% | 1 | 100.00% |
/* RFC 5961 7 [ACK Throttling] */
static void tcp_send_challenge_ack(struct sock *sk, const struct sk_buff *skb)
{
/* unprotected vars, we dont care of overwrites */
static u32 challenge_timestamp;
static unsigned int challenge_count;
struct tcp_sock *tp = tcp_sk(sk);
u32 count, now;
/* First check our per-socket dupack rate limit. */
if (__tcp_oow_rate_limited(sock_net(sk),
LINUX_MIB_TCPACKSKIPPEDCHALLENGE,
&tp->last_oow_ack_time))
return;
/* Then check host-wide RFC 5961 rate limit. */
now = jiffies / HZ;
if (now != challenge_timestamp) {
u32 half = (sysctl_tcp_challenge_ack_limit + 1) >> 1;
challenge_timestamp = now;
WRITE_ONCE(challenge_count, half +
prandom_u32_max(sysctl_tcp_challenge_ack_limit));
}
count = READ_ONCE(challenge_count);
if (count > 0) {
WRITE_ONCE(challenge_count, count - 1);
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPCHALLENGEACK);
tcp_send_ack(sk);
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| eric dumazet | eric dumazet | 103 | 72.54% | 3 | 60.00% |
| neal cardwell | neal cardwell | 38 | 26.76% | 1 | 20.00% |
| jason baron | jason baron | 1 | 0.70% | 1 | 20.00% |
| Total | 142 | 100.00% | 5 | 100.00% |
static void tcp_store_ts_recent(struct tcp_sock *tp)
{
tp->rx_opt.ts_recent = tp->rx_opt.rcv_tsval;
tp->rx_opt.ts_recent_stamp = get_seconds();
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| eric dumazet | eric dumazet | 32 | 100.00% | 1 | 100.00% |
| Total | 32 | 100.00% | 1 | 100.00% |
static void tcp_replace_ts_recent(struct tcp_sock *tp, u32 seq)
{
if (tp->rx_opt.saw_tstamp && !after(seq, tp->rcv_wup)) {
/* PAWS bug workaround wrt. ACK frames, the PAWS discard
* extra check below makes sure this can only happen
* for pure ACK frames. -DaveM
*
* Not only, also it occurs for expired timestamps.
*/
if (tcp_paws_check(&tp->rx_opt, 0))
tcp_store_ts_recent(tp);
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| david s. miller | david s. miller | 28 | 53.85% | 1 | 50.00% |
| eric dumazet | eric dumazet | 24 | 46.15% | 1 | 50.00% |
| Total | 52 | 100.00% | 2 | 100.00% |
/* This routine deals with acks during a TLP episode.
* We mark the end of a TLP episode on receiving TLP dupack or when
* ack is after tlp_high_seq.
* Ref: loss detection algorithm in draft-dukkipati-tcpm-tcp-loss-probe.
*/
static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag)
{
struct tcp_sock *tp = tcp_sk(sk);
if (before(ack, tp->tlp_high_seq))
return;
if (flag & FLAG_DSACKING_ACK) {
/* This DSACK means original and TLP probe arrived; no loss */
tp->tlp_high_seq = 0;
} else if (after