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01a523b071
Create a helper to model TCP exponential backoff for the next patch. This is pure refactor w no behavior change. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
760 lines
22 KiB
C
760 lines
22 KiB
C
/*
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* INET An implementation of the TCP/IP protocol suite for the LINUX
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* operating system. INET is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* Implementation of the Transmission Control Protocol(TCP).
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*
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* Authors: Ross Biro
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* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
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* Mark Evans, <evansmp@uhura.aston.ac.uk>
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* Corey Minyard <wf-rch!minyard@relay.EU.net>
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* Florian La Roche, <flla@stud.uni-sb.de>
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* Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
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* Linus Torvalds, <torvalds@cs.helsinki.fi>
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* Alan Cox, <gw4pts@gw4pts.ampr.org>
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* Matthew Dillon, <dillon@apollo.west.oic.com>
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* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
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* Jorge Cwik, <jorge@laser.satlink.net>
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*/
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#include <linux/module.h>
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#include <linux/gfp.h>
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#include <net/tcp.h>
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static u32 tcp_clamp_rto_to_user_timeout(const struct sock *sk)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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u32 elapsed, start_ts;
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s32 remaining;
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start_ts = tcp_sk(sk)->retrans_stamp;
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if (!icsk->icsk_user_timeout)
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return icsk->icsk_rto;
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elapsed = tcp_time_stamp(tcp_sk(sk)) - start_ts;
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remaining = icsk->icsk_user_timeout - elapsed;
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if (remaining <= 0)
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return 1; /* user timeout has passed; fire ASAP */
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return min_t(u32, icsk->icsk_rto, msecs_to_jiffies(remaining));
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}
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/**
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* tcp_write_err() - close socket and save error info
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* @sk: The socket the error has appeared on.
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*
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* Returns: Nothing (void)
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*/
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static void tcp_write_err(struct sock *sk)
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{
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sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT;
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sk->sk_error_report(sk);
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tcp_write_queue_purge(sk);
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tcp_done(sk);
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__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONTIMEOUT);
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}
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/**
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* tcp_out_of_resources() - Close socket if out of resources
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* @sk: pointer to current socket
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* @do_reset: send a last packet with reset flag
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*
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* Do not allow orphaned sockets to eat all our resources.
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* This is direct violation of TCP specs, but it is required
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* to prevent DoS attacks. It is called when a retransmission timeout
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* or zero probe timeout occurs on orphaned socket.
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*
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* Also close if our net namespace is exiting; in that case there is no
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* hope of ever communicating again since all netns interfaces are already
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* down (or about to be down), and we need to release our dst references,
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* which have been moved to the netns loopback interface, so the namespace
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* can finish exiting. This condition is only possible if we are a kernel
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* socket, as those do not hold references to the namespace.
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*
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* Criteria is still not confirmed experimentally and may change.
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* We kill the socket, if:
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* 1. If number of orphaned sockets exceeds an administratively configured
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* limit.
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* 2. If we have strong memory pressure.
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* 3. If our net namespace is exiting.
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*/
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static int tcp_out_of_resources(struct sock *sk, bool do_reset)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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int shift = 0;
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/* If peer does not open window for long time, or did not transmit
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* anything for long time, penalize it. */
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if ((s32)(tcp_jiffies32 - tp->lsndtime) > 2*TCP_RTO_MAX || !do_reset)
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shift++;
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/* If some dubious ICMP arrived, penalize even more. */
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if (sk->sk_err_soft)
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shift++;
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if (tcp_check_oom(sk, shift)) {
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/* Catch exceptional cases, when connection requires reset.
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* 1. Last segment was sent recently. */
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if ((s32)(tcp_jiffies32 - tp->lsndtime) <= TCP_TIMEWAIT_LEN ||
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/* 2. Window is closed. */
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(!tp->snd_wnd && !tp->packets_out))
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do_reset = true;
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if (do_reset)
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tcp_send_active_reset(sk, GFP_ATOMIC);
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tcp_done(sk);
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__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONMEMORY);
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return 1;
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}
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if (!check_net(sock_net(sk))) {
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/* Not possible to send reset; just close */
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tcp_done(sk);
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return 1;
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}
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return 0;
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}
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/**
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* tcp_orphan_retries() - Returns maximal number of retries on an orphaned socket
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* @sk: Pointer to the current socket.
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* @alive: bool, socket alive state
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*/
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static int tcp_orphan_retries(struct sock *sk, bool alive)
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{
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int retries = sock_net(sk)->ipv4.sysctl_tcp_orphan_retries; /* May be zero. */
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/* We know from an ICMP that something is wrong. */
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if (sk->sk_err_soft && !alive)
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retries = 0;
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/* However, if socket sent something recently, select some safe
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* number of retries. 8 corresponds to >100 seconds with minimal
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* RTO of 200msec. */
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if (retries == 0 && alive)
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retries = 8;
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return retries;
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}
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static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk)
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{
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const struct net *net = sock_net(sk);
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int mss;
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/* Black hole detection */
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if (!net->ipv4.sysctl_tcp_mtu_probing)
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return;
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if (!icsk->icsk_mtup.enabled) {
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icsk->icsk_mtup.enabled = 1;
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icsk->icsk_mtup.probe_timestamp = tcp_jiffies32;
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} else {
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mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1;
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mss = min(net->ipv4.sysctl_tcp_base_mss, mss);
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mss = max(mss, 68 - tcp_sk(sk)->tcp_header_len);
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icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss);
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}
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tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
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}
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static unsigned int tcp_model_timeout(struct sock *sk,
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unsigned int boundary,
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unsigned int rto_base)
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{
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unsigned int linear_backoff_thresh, timeout;
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linear_backoff_thresh = ilog2(TCP_RTO_MAX / rto_base);
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if (boundary <= linear_backoff_thresh)
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timeout = ((2 << boundary) - 1) * rto_base;
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else
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timeout = ((2 << linear_backoff_thresh) - 1) * rto_base +
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(boundary - linear_backoff_thresh) * TCP_RTO_MAX;
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return jiffies_to_msecs(timeout);
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}
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/**
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* retransmits_timed_out() - returns true if this connection has timed out
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* @sk: The current socket
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* @boundary: max number of retransmissions
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* @timeout: A custom timeout value.
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* If set to 0 the default timeout is calculated and used.
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* Using TCP_RTO_MIN and the number of unsuccessful retransmits.
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*
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* The default "timeout" value this function can calculate and use
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* is equivalent to the timeout of a TCP Connection
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* after "boundary" unsuccessful, exponentially backed-off
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* retransmissions with an initial RTO of TCP_RTO_MIN.
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*/
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static bool retransmits_timed_out(struct sock *sk,
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unsigned int boundary,
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unsigned int timeout)
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{
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unsigned int start_ts;
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if (!inet_csk(sk)->icsk_retransmits)
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return false;
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start_ts = tcp_sk(sk)->retrans_stamp;
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if (likely(timeout == 0))
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timeout = tcp_model_timeout(sk, boundary, TCP_RTO_MIN);
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return (s32)(tcp_time_stamp(tcp_sk(sk)) - start_ts - timeout) >= 0;
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}
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/* A write timeout has occurred. Process the after effects. */
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static int tcp_write_timeout(struct sock *sk)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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struct tcp_sock *tp = tcp_sk(sk);
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struct net *net = sock_net(sk);
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bool expired, do_reset;
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int retry_until;
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if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
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if (icsk->icsk_retransmits) {
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dst_negative_advice(sk);
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} else {
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sk_rethink_txhash(sk);
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}
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retry_until = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_syn_retries;
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expired = icsk->icsk_retransmits >= retry_until;
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} else {
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if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1, 0)) {
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/* Black hole detection */
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tcp_mtu_probing(icsk, sk);
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dst_negative_advice(sk);
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} else {
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sk_rethink_txhash(sk);
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}
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retry_until = net->ipv4.sysctl_tcp_retries2;
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if (sock_flag(sk, SOCK_DEAD)) {
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const bool alive = icsk->icsk_rto < TCP_RTO_MAX;
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retry_until = tcp_orphan_retries(sk, alive);
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do_reset = alive ||
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!retransmits_timed_out(sk, retry_until, 0);
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if (tcp_out_of_resources(sk, do_reset))
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return 1;
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}
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expired = retransmits_timed_out(sk, retry_until,
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icsk->icsk_user_timeout);
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}
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tcp_fastopen_active_detect_blackhole(sk, expired);
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if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RTO_CB_FLAG))
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tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RTO_CB,
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icsk->icsk_retransmits,
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icsk->icsk_rto, (int)expired);
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if (expired) {
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/* Has it gone just too far? */
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tcp_write_err(sk);
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return 1;
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}
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return 0;
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}
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/* Called with BH disabled */
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void tcp_delack_timer_handler(struct sock *sk)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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sk_mem_reclaim_partial(sk);
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if (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) ||
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!(icsk->icsk_ack.pending & ICSK_ACK_TIMER))
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goto out;
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if (time_after(icsk->icsk_ack.timeout, jiffies)) {
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sk_reset_timer(sk, &icsk->icsk_delack_timer, icsk->icsk_ack.timeout);
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goto out;
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}
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icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER;
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if (inet_csk_ack_scheduled(sk)) {
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if (!icsk->icsk_ack.pingpong) {
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/* Delayed ACK missed: inflate ATO. */
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icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1, icsk->icsk_rto);
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} else {
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/* Delayed ACK missed: leave pingpong mode and
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* deflate ATO.
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*/
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icsk->icsk_ack.pingpong = 0;
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icsk->icsk_ack.ato = TCP_ATO_MIN;
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}
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tcp_mstamp_refresh(tcp_sk(sk));
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tcp_send_ack(sk);
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__NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKS);
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}
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out:
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if (tcp_under_memory_pressure(sk))
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sk_mem_reclaim(sk);
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}
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/**
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* tcp_delack_timer() - The TCP delayed ACK timeout handler
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* @data: Pointer to the current socket. (gets casted to struct sock *)
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*
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* This function gets (indirectly) called when the kernel timer for a TCP packet
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* of this socket expires. Calls tcp_delack_timer_handler() to do the actual work.
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*
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* Returns: Nothing (void)
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*/
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static void tcp_delack_timer(struct timer_list *t)
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{
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struct inet_connection_sock *icsk =
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from_timer(icsk, t, icsk_delack_timer);
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struct sock *sk = &icsk->icsk_inet.sk;
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bh_lock_sock(sk);
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if (!sock_owned_by_user(sk)) {
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tcp_delack_timer_handler(sk);
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} else {
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icsk->icsk_ack.blocked = 1;
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__NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
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/* deleguate our work to tcp_release_cb() */
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if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, &sk->sk_tsq_flags))
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sock_hold(sk);
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}
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bh_unlock_sock(sk);
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sock_put(sk);
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}
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static void tcp_probe_timer(struct sock *sk)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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struct sk_buff *skb = tcp_send_head(sk);
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struct tcp_sock *tp = tcp_sk(sk);
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int max_probes;
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u32 start_ts;
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if (tp->packets_out || !skb) {
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icsk->icsk_probes_out = 0;
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return;
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}
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/* RFC 1122 4.2.2.17 requires the sender to stay open indefinitely as
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* long as the receiver continues to respond probes. We support this by
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* default and reset icsk_probes_out with incoming ACKs. But if the
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* socket is orphaned or the user specifies TCP_USER_TIMEOUT, we
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* kill the socket when the retry count and the time exceeds the
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* corresponding system limit. We also implement similar policy when
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* we use RTO to probe window in tcp_retransmit_timer().
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*/
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start_ts = tcp_skb_timestamp(skb);
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if (!start_ts)
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skb->skb_mstamp_ns = tp->tcp_clock_cache;
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else if (icsk->icsk_user_timeout &&
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(s32)(tcp_time_stamp(tp) - start_ts) > icsk->icsk_user_timeout)
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goto abort;
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max_probes = sock_net(sk)->ipv4.sysctl_tcp_retries2;
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if (sock_flag(sk, SOCK_DEAD)) {
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const bool alive = inet_csk_rto_backoff(icsk, TCP_RTO_MAX) < TCP_RTO_MAX;
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max_probes = tcp_orphan_retries(sk, alive);
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if (!alive && icsk->icsk_backoff >= max_probes)
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goto abort;
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if (tcp_out_of_resources(sk, true))
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return;
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}
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if (icsk->icsk_probes_out >= max_probes) {
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abort: tcp_write_err(sk);
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} else {
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/* Only send another probe if we didn't close things up. */
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tcp_send_probe0(sk);
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}
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}
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/*
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* Timer for Fast Open socket to retransmit SYNACK. Note that the
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* sk here is the child socket, not the parent (listener) socket.
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*/
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static void tcp_fastopen_synack_timer(struct sock *sk)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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int max_retries = icsk->icsk_syn_retries ? :
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sock_net(sk)->ipv4.sysctl_tcp_synack_retries + 1; /* add one more retry for fastopen */
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struct tcp_sock *tp = tcp_sk(sk);
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struct request_sock *req;
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req = tcp_sk(sk)->fastopen_rsk;
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req->rsk_ops->syn_ack_timeout(req);
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if (req->num_timeout >= max_retries) {
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tcp_write_err(sk);
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return;
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}
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/* XXX (TFO) - Unlike regular SYN-ACK retransmit, we ignore error
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* returned from rtx_syn_ack() to make it more persistent like
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* regular retransmit because if the child socket has been accepted
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* it's not good to give up too easily.
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*/
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inet_rtx_syn_ack(sk, req);
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req->num_timeout++;
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icsk->icsk_retransmits++;
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if (!tp->retrans_stamp)
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tp->retrans_stamp = tcp_time_stamp(tp);
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inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
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TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
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}
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/**
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* tcp_retransmit_timer() - The TCP retransmit timeout handler
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* @sk: Pointer to the current socket.
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*
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* This function gets called when the kernel timer for a TCP packet
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* of this socket expires.
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*
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* It handles retransmission, timer adjustment and other necesarry measures.
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*
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* Returns: Nothing (void)
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*/
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void tcp_retransmit_timer(struct sock *sk)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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struct net *net = sock_net(sk);
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struct inet_connection_sock *icsk = inet_csk(sk);
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if (tp->fastopen_rsk) {
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WARN_ON_ONCE(sk->sk_state != TCP_SYN_RECV &&
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sk->sk_state != TCP_FIN_WAIT1);
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tcp_fastopen_synack_timer(sk);
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/* Before we receive ACK to our SYN-ACK don't retransmit
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* anything else (e.g., data or FIN segments).
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*/
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return;
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}
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if (!tp->packets_out || WARN_ON_ONCE(tcp_rtx_queue_empty(sk)))
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return;
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tp->tlp_high_seq = 0;
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if (!tp->snd_wnd && !sock_flag(sk, SOCK_DEAD) &&
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!((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))) {
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/* Receiver dastardly shrinks window. Our retransmits
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* become zero probes, but we should not timeout this
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* connection. If the socket is an orphan, time it out,
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* we cannot allow such beasts to hang infinitely.
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*/
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struct inet_sock *inet = inet_sk(sk);
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if (sk->sk_family == AF_INET) {
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net_dbg_ratelimited("Peer %pI4:%u/%u unexpectedly shrunk window %u:%u (repaired)\n",
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&inet->inet_daddr,
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|
ntohs(inet->inet_dport),
|
|
inet->inet_num,
|
|
tp->snd_una, tp->snd_nxt);
|
|
}
|
|
#if IS_ENABLED(CONFIG_IPV6)
|
|
else if (sk->sk_family == AF_INET6) {
|
|
net_dbg_ratelimited("Peer %pI6:%u/%u unexpectedly shrunk window %u:%u (repaired)\n",
|
|
&sk->sk_v6_daddr,
|
|
ntohs(inet->inet_dport),
|
|
inet->inet_num,
|
|
tp->snd_una, tp->snd_nxt);
|
|
}
|
|
#endif
|
|
if (tcp_jiffies32 - tp->rcv_tstamp > TCP_RTO_MAX) {
|
|
tcp_write_err(sk);
|
|
goto out;
|
|
}
|
|
tcp_enter_loss(sk);
|
|
tcp_retransmit_skb(sk, tcp_rtx_queue_head(sk), 1);
|
|
__sk_dst_reset(sk);
|
|
goto out_reset_timer;
|
|
}
|
|
|
|
__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPTIMEOUTS);
|
|
if (tcp_write_timeout(sk))
|
|
goto out;
|
|
|
|
if (icsk->icsk_retransmits == 0) {
|
|
int mib_idx = 0;
|
|
|
|
if (icsk->icsk_ca_state == TCP_CA_Recovery) {
|
|
if (tcp_is_sack(tp))
|
|
mib_idx = LINUX_MIB_TCPSACKRECOVERYFAIL;
|
|
else
|
|
mib_idx = LINUX_MIB_TCPRENORECOVERYFAIL;
|
|
} else if (icsk->icsk_ca_state == TCP_CA_Loss) {
|
|
mib_idx = LINUX_MIB_TCPLOSSFAILURES;
|
|
} else if ((icsk->icsk_ca_state == TCP_CA_Disorder) ||
|
|
tp->sacked_out) {
|
|
if (tcp_is_sack(tp))
|
|
mib_idx = LINUX_MIB_TCPSACKFAILURES;
|
|
else
|
|
mib_idx = LINUX_MIB_TCPRENOFAILURES;
|
|
}
|
|
if (mib_idx)
|
|
__NET_INC_STATS(sock_net(sk), mib_idx);
|
|
}
|
|
|
|
tcp_enter_loss(sk);
|
|
|
|
if (tcp_retransmit_skb(sk, tcp_rtx_queue_head(sk), 1) > 0) {
|
|
/* Retransmission failed because of local congestion,
|
|
* do not backoff.
|
|
*/
|
|
if (!icsk->icsk_retransmits)
|
|
icsk->icsk_retransmits = 1;
|
|
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
|
|
min(icsk->icsk_rto, TCP_RESOURCE_PROBE_INTERVAL),
|
|
TCP_RTO_MAX);
|
|
goto out;
|
|
}
|
|
|
|
/* Increase the timeout each time we retransmit. Note that
|
|
* we do not increase the rtt estimate. rto is initialized
|
|
* from rtt, but increases here. Jacobson (SIGCOMM 88) suggests
|
|
* that doubling rto each time is the least we can get away with.
|
|
* In KA9Q, Karn uses this for the first few times, and then
|
|
* goes to quadratic. netBSD doubles, but only goes up to *64,
|
|
* and clamps at 1 to 64 sec afterwards. Note that 120 sec is
|
|
* defined in the protocol as the maximum possible RTT. I guess
|
|
* we'll have to use something other than TCP to talk to the
|
|
* University of Mars.
|
|
*
|
|
* PAWS allows us longer timeouts and large windows, so once
|
|
* implemented ftp to mars will work nicely. We will have to fix
|
|
* the 120 second clamps though!
|
|
*/
|
|
icsk->icsk_backoff++;
|
|
icsk->icsk_retransmits++;
|
|
|
|
out_reset_timer:
|
|
/* If stream is thin, use linear timeouts. Since 'icsk_backoff' is
|
|
* used to reset timer, set to 0. Recalculate 'icsk_rto' as this
|
|
* might be increased if the stream oscillates between thin and thick,
|
|
* thus the old value might already be too high compared to the value
|
|
* set by 'tcp_set_rto' in tcp_input.c which resets the rto without
|
|
* backoff. Limit to TCP_THIN_LINEAR_RETRIES before initiating
|
|
* exponential backoff behaviour to avoid continue hammering
|
|
* linear-timeout retransmissions into a black hole
|
|
*/
|
|
if (sk->sk_state == TCP_ESTABLISHED &&
|
|
(tp->thin_lto || net->ipv4.sysctl_tcp_thin_linear_timeouts) &&
|
|
tcp_stream_is_thin(tp) &&
|
|
icsk->icsk_retransmits <= TCP_THIN_LINEAR_RETRIES) {
|
|
icsk->icsk_backoff = 0;
|
|
icsk->icsk_rto = min(__tcp_set_rto(tp), TCP_RTO_MAX);
|
|
} else {
|
|
/* Use normal (exponential) backoff */
|
|
icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX);
|
|
}
|
|
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
|
|
tcp_clamp_rto_to_user_timeout(sk), TCP_RTO_MAX);
|
|
if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1 + 1, 0))
|
|
__sk_dst_reset(sk);
|
|
|
|
out:;
|
|
}
|
|
|
|
/* Called with bottom-half processing disabled.
|
|
Called by tcp_write_timer() */
|
|
void tcp_write_timer_handler(struct sock *sk)
|
|
{
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
int event;
|
|
|
|
if (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) ||
|
|
!icsk->icsk_pending)
|
|
goto out;
|
|
|
|
if (time_after(icsk->icsk_timeout, jiffies)) {
|
|
sk_reset_timer(sk, &icsk->icsk_retransmit_timer, icsk->icsk_timeout);
|
|
goto out;
|
|
}
|
|
|
|
tcp_mstamp_refresh(tcp_sk(sk));
|
|
event = icsk->icsk_pending;
|
|
|
|
switch (event) {
|
|
case ICSK_TIME_REO_TIMEOUT:
|
|
tcp_rack_reo_timeout(sk);
|
|
break;
|
|
case ICSK_TIME_LOSS_PROBE:
|
|
tcp_send_loss_probe(sk);
|
|
break;
|
|
case ICSK_TIME_RETRANS:
|
|
icsk->icsk_pending = 0;
|
|
tcp_retransmit_timer(sk);
|
|
break;
|
|
case ICSK_TIME_PROBE0:
|
|
icsk->icsk_pending = 0;
|
|
tcp_probe_timer(sk);
|
|
break;
|
|
}
|
|
|
|
out:
|
|
sk_mem_reclaim(sk);
|
|
}
|
|
|
|
static void tcp_write_timer(struct timer_list *t)
|
|
{
|
|
struct inet_connection_sock *icsk =
|
|
from_timer(icsk, t, icsk_retransmit_timer);
|
|
struct sock *sk = &icsk->icsk_inet.sk;
|
|
|
|
bh_lock_sock(sk);
|
|
if (!sock_owned_by_user(sk)) {
|
|
tcp_write_timer_handler(sk);
|
|
} else {
|
|
/* delegate our work to tcp_release_cb() */
|
|
if (!test_and_set_bit(TCP_WRITE_TIMER_DEFERRED, &sk->sk_tsq_flags))
|
|
sock_hold(sk);
|
|
}
|
|
bh_unlock_sock(sk);
|
|
sock_put(sk);
|
|
}
|
|
|
|
void tcp_syn_ack_timeout(const struct request_sock *req)
|
|
{
|
|
struct net *net = read_pnet(&inet_rsk(req)->ireq_net);
|
|
|
|
__NET_INC_STATS(net, LINUX_MIB_TCPTIMEOUTS);
|
|
}
|
|
EXPORT_SYMBOL(tcp_syn_ack_timeout);
|
|
|
|
void tcp_set_keepalive(struct sock *sk, int val)
|
|
{
|
|
if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))
|
|
return;
|
|
|
|
if (val && !sock_flag(sk, SOCK_KEEPOPEN))
|
|
inet_csk_reset_keepalive_timer(sk, keepalive_time_when(tcp_sk(sk)));
|
|
else if (!val)
|
|
inet_csk_delete_keepalive_timer(sk);
|
|
}
|
|
EXPORT_SYMBOL_GPL(tcp_set_keepalive);
|
|
|
|
|
|
static void tcp_keepalive_timer (struct timer_list *t)
|
|
{
|
|
struct sock *sk = from_timer(sk, t, sk_timer);
|
|
struct inet_connection_sock *icsk = inet_csk(sk);
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
u32 elapsed;
|
|
|
|
/* Only process if socket is not in use. */
|
|
bh_lock_sock(sk);
|
|
if (sock_owned_by_user(sk)) {
|
|
/* Try again later. */
|
|
inet_csk_reset_keepalive_timer (sk, HZ/20);
|
|
goto out;
|
|
}
|
|
|
|
if (sk->sk_state == TCP_LISTEN) {
|
|
pr_err("Hmm... keepalive on a LISTEN ???\n");
|
|
goto out;
|
|
}
|
|
|
|
tcp_mstamp_refresh(tp);
|
|
if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) {
|
|
if (tp->linger2 >= 0) {
|
|
const int tmo = tcp_fin_time(sk) - TCP_TIMEWAIT_LEN;
|
|
|
|
if (tmo > 0) {
|
|
tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
|
|
goto out;
|
|
}
|
|
}
|
|
tcp_send_active_reset(sk, GFP_ATOMIC);
|
|
goto death;
|
|
}
|
|
|
|
if (!sock_flag(sk, SOCK_KEEPOPEN) ||
|
|
((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_SYN_SENT)))
|
|
goto out;
|
|
|
|
elapsed = keepalive_time_when(tp);
|
|
|
|
/* It is alive without keepalive 8) */
|
|
if (tp->packets_out || !tcp_write_queue_empty(sk))
|
|
goto resched;
|
|
|
|
elapsed = keepalive_time_elapsed(tp);
|
|
|
|
if (elapsed >= keepalive_time_when(tp)) {
|
|
/* If the TCP_USER_TIMEOUT option is enabled, use that
|
|
* to determine when to timeout instead.
|
|
*/
|
|
if ((icsk->icsk_user_timeout != 0 &&
|
|
elapsed >= msecs_to_jiffies(icsk->icsk_user_timeout) &&
|
|
icsk->icsk_probes_out > 0) ||
|
|
(icsk->icsk_user_timeout == 0 &&
|
|
icsk->icsk_probes_out >= keepalive_probes(tp))) {
|
|
tcp_send_active_reset(sk, GFP_ATOMIC);
|
|
tcp_write_err(sk);
|
|
goto out;
|
|
}
|
|
if (tcp_write_wakeup(sk, LINUX_MIB_TCPKEEPALIVE) <= 0) {
|
|
icsk->icsk_probes_out++;
|
|
elapsed = keepalive_intvl_when(tp);
|
|
} else {
|
|
/* If keepalive was lost due to local congestion,
|
|
* try harder.
|
|
*/
|
|
elapsed = TCP_RESOURCE_PROBE_INTERVAL;
|
|
}
|
|
} else {
|
|
/* It is tp->rcv_tstamp + keepalive_time_when(tp) */
|
|
elapsed = keepalive_time_when(tp) - elapsed;
|
|
}
|
|
|
|
sk_mem_reclaim(sk);
|
|
|
|
resched:
|
|
inet_csk_reset_keepalive_timer (sk, elapsed);
|
|
goto out;
|
|
|
|
death:
|
|
tcp_done(sk);
|
|
|
|
out:
|
|
bh_unlock_sock(sk);
|
|
sock_put(sk);
|
|
}
|
|
|
|
static enum hrtimer_restart tcp_compressed_ack_kick(struct hrtimer *timer)
|
|
{
|
|
struct tcp_sock *tp = container_of(timer, struct tcp_sock, compressed_ack_timer);
|
|
struct sock *sk = (struct sock *)tp;
|
|
|
|
bh_lock_sock(sk);
|
|
if (!sock_owned_by_user(sk)) {
|
|
if (tp->compressed_ack > TCP_FASTRETRANS_THRESH)
|
|
tcp_send_ack(sk);
|
|
} else {
|
|
if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED,
|
|
&sk->sk_tsq_flags))
|
|
sock_hold(sk);
|
|
}
|
|
bh_unlock_sock(sk);
|
|
|
|
sock_put(sk);
|
|
|
|
return HRTIMER_NORESTART;
|
|
}
|
|
|
|
void tcp_init_xmit_timers(struct sock *sk)
|
|
{
|
|
inet_csk_init_xmit_timers(sk, &tcp_write_timer, &tcp_delack_timer,
|
|
&tcp_keepalive_timer);
|
|
hrtimer_init(&tcp_sk(sk)->pacing_timer, CLOCK_MONOTONIC,
|
|
HRTIMER_MODE_ABS_PINNED_SOFT);
|
|
tcp_sk(sk)->pacing_timer.function = tcp_pace_kick;
|
|
|
|
hrtimer_init(&tcp_sk(sk)->compressed_ack_timer, CLOCK_MONOTONIC,
|
|
HRTIMER_MODE_REL_PINNED_SOFT);
|
|
tcp_sk(sk)->compressed_ack_timer.function = tcp_compressed_ack_kick;
|
|
}
|