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614e8316aa
Back in 2015, Van Jacobson suggested to use usec resolution in TCP TS values. This has been implemented in our private kernels. Goals were : 1) better observability of delays in networking stacks. 2) better disambiguation of events based on TSval/ecr values. 3) building block for congestion control modules needing usec resolution. Back then we implemented a schem based on private SYN options to negotiate the feature. For upstream submission, we chose to use a route attribute, because this feature is probably going to be used in private networks [1] [2]. ip route add 10/8 ... features tcp_usec_ts Note that RFC 7323 recommends a "timestamp clock frequency in the range 1 ms to 1 sec per tick.", but also mentions "the maximum acceptable clock frequency is one tick every 59 ns." [1] Unfortunately RFC 7323 5.5 (Outdated Timestamps) suggests to invalidate TS.Recent values after a flow was idle for more than 24 days. This is the part making usec_ts a problem for peers following this recommendation for long living idle flows. [2] Attempts to standardize usec ts went nowhere: https://www.ietf.org/proceedings/97/slides/slides-97-tcpm-tcp-options-for-low-latency-00.pdf https://datatracker.ietf.org/doc/draft-wang-tcpm-low-latency-opt/ Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
131 lines
3.8 KiB
C
131 lines
3.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* INET An implementation of the TCP/IP protocol suite for the LINUX
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* operating system. INET is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* Definitions for a generic INET TIMEWAIT sock
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*
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* From code originally in net/tcp.h
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*/
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#ifndef _INET_TIMEWAIT_SOCK_
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#define _INET_TIMEWAIT_SOCK_
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#include <linux/list.h>
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#include <linux/timer.h>
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#include <linux/types.h>
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#include <linux/workqueue.h>
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#include <net/inet_sock.h>
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#include <net/sock.h>
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#include <net/tcp_states.h>
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#include <net/timewait_sock.h>
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#include <linux/atomic.h>
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struct inet_bind_bucket;
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/*
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* This is a TIME_WAIT sock. It works around the memory consumption
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* problems of sockets in such a state on heavily loaded servers, but
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* without violating the protocol specification.
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*/
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struct inet_timewait_sock {
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/*
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* Now struct sock also uses sock_common, so please just
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* don't add nothing before this first member (__tw_common) --acme
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*/
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struct sock_common __tw_common;
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#define tw_family __tw_common.skc_family
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#define tw_state __tw_common.skc_state
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#define tw_reuse __tw_common.skc_reuse
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#define tw_reuseport __tw_common.skc_reuseport
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#define tw_ipv6only __tw_common.skc_ipv6only
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#define tw_bound_dev_if __tw_common.skc_bound_dev_if
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#define tw_node __tw_common.skc_nulls_node
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#define tw_bind_node __tw_common.skc_bind_node
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#define tw_refcnt __tw_common.skc_refcnt
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#define tw_hash __tw_common.skc_hash
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#define tw_prot __tw_common.skc_prot
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#define tw_net __tw_common.skc_net
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#define tw_daddr __tw_common.skc_daddr
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#define tw_v6_daddr __tw_common.skc_v6_daddr
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#define tw_rcv_saddr __tw_common.skc_rcv_saddr
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#define tw_v6_rcv_saddr __tw_common.skc_v6_rcv_saddr
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#define tw_dport __tw_common.skc_dport
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#define tw_num __tw_common.skc_num
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#define tw_cookie __tw_common.skc_cookie
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#define tw_dr __tw_common.skc_tw_dr
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__u32 tw_mark;
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volatile unsigned char tw_substate;
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unsigned char tw_rcv_wscale;
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/* Socket demultiplex comparisons on incoming packets. */
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/* these three are in inet_sock */
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__be16 tw_sport;
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/* And these are ours. */
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unsigned int tw_transparent : 1,
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tw_flowlabel : 20,
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tw_usec_ts : 1,
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tw_pad : 2, /* 2 bits hole */
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tw_tos : 8;
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u32 tw_txhash;
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u32 tw_priority;
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struct timer_list tw_timer;
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struct inet_bind_bucket *tw_tb;
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struct inet_bind2_bucket *tw_tb2;
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struct hlist_node tw_bind2_node;
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};
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#define tw_tclass tw_tos
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#define twsk_for_each_bound_bhash2(__tw, list) \
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hlist_for_each_entry(__tw, list, tw_bind2_node)
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static inline struct inet_timewait_sock *inet_twsk(const struct sock *sk)
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{
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return (struct inet_timewait_sock *)sk;
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}
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void inet_twsk_free(struct inet_timewait_sock *tw);
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void inet_twsk_put(struct inet_timewait_sock *tw);
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void inet_twsk_bind_unhash(struct inet_timewait_sock *tw,
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struct inet_hashinfo *hashinfo);
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struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk,
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struct inet_timewait_death_row *dr,
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const int state);
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void inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk,
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struct inet_hashinfo *hashinfo);
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void __inet_twsk_schedule(struct inet_timewait_sock *tw, int timeo,
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bool rearm);
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static inline void inet_twsk_schedule(struct inet_timewait_sock *tw, int timeo)
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{
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__inet_twsk_schedule(tw, timeo, false);
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}
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static inline void inet_twsk_reschedule(struct inet_timewait_sock *tw, int timeo)
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{
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__inet_twsk_schedule(tw, timeo, true);
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}
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void inet_twsk_deschedule_put(struct inet_timewait_sock *tw);
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void inet_twsk_purge(struct inet_hashinfo *hashinfo, int family);
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static inline
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struct net *twsk_net(const struct inet_timewait_sock *twsk)
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{
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return read_pnet(&twsk->tw_net);
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}
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static inline
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void twsk_net_set(struct inet_timewait_sock *twsk, struct net *net)
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{
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write_pnet(&twsk->tw_net, net);
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}
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#endif /* _INET_TIMEWAIT_SOCK_ */
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