/*
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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 the TCP protocol.
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*
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* Version: @(#)tcp.h 1.0.2 04/28/93
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*
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* Author: Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _LINUX_TCP_H
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#define _LINUX_TCP_H
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#include <linux/skbuff.h>
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#include <linux/win_minmax.h>
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#include <net/sock.h>
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#include <net/inet_connection_sock.h>
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#include <net/inet_timewait_sock.h>
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#include <uapi/linux/tcp.h>
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static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
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{
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return (struct tcphdr *)skb_transport_header(skb);
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}
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static inline unsigned int __tcp_hdrlen(const struct tcphdr *th)
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{
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return th->doff * 4;
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}
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static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
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{
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return __tcp_hdrlen(tcp_hdr(skb));
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}
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static inline struct tcphdr *inner_tcp_hdr(const struct sk_buff *skb)
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{
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return (struct tcphdr *)skb_inner_transport_header(skb);
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}
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static inline unsigned int inner_tcp_hdrlen(const struct sk_buff *skb)
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{
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return inner_tcp_hdr(skb)->doff * 4;
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}
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static inline unsigned int tcp_optlen(const struct sk_buff *skb)
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{
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return (tcp_hdr(skb)->doff - 5) * 4;
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}
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/* TCP Fast Open */
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#define TCP_FASTOPEN_COOKIE_MIN 4 /* Min Fast Open Cookie size in bytes */
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#define TCP_FASTOPEN_COOKIE_MAX 16 /* Max Fast Open Cookie size in bytes */
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#define TCP_FASTOPEN_COOKIE_SIZE 8 /* the size employed by this impl. */
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/* TCP Fast Open Cookie as stored in memory */
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struct tcp_fastopen_cookie {
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union {
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u8 val[TCP_FASTOPEN_COOKIE_MAX];
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#if IS_ENABLED(CONFIG_IPV6)
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struct in6_addr addr;
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#endif
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};
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s8 len;
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bool exp; /* In RFC6994 experimental option format */
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};
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/* This defines a selective acknowledgement block. */
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struct tcp_sack_block_wire {
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__be32 start_seq;
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__be32 end_seq;
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};
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struct tcp_sack_block {
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u32 start_seq;
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u32 end_seq;
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};
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/*These are used to set the sack_ok field in struct tcp_options_received */
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#define TCP_SACK_SEEN (1 << 0) /*1 = peer is SACK capable, */
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#define TCP_FACK_ENABLED (1 << 1) /*1 = FACK is enabled locally*/
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#define TCP_DSACK_SEEN (1 << 2) /*1 = DSACK was received from peer*/
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struct tcp_options_received {
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/* PAWS/RTTM data */
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long ts_recent_stamp;/* Time we stored ts_recent (for aging) */
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u32 ts_recent; /* Time stamp to echo next */
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u32 rcv_tsval; /* Time stamp value */
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u32 rcv_tsecr; /* Time stamp echo reply */
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u16 saw_tstamp : 1, /* Saw TIMESTAMP on last packet */
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tstamp_ok : 1, /* TIMESTAMP seen on SYN packet */
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dsack : 1, /* D-SACK is scheduled */
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wscale_ok : 1, /* Wscale seen on SYN packet */
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sack_ok : 4, /* SACK seen on SYN packet */
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snd_wscale : 4, /* Window scaling received from sender */
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rcv_wscale : 4; /* Window scaling to send to receiver */
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u8 num_sacks; /* Number of SACK blocks */
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u16 user_mss; /* mss requested by user in ioctl */
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u16 mss_clamp; /* Maximal mss, negotiated at connection setup */
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};
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static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
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{
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rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
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rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
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}
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/* This is the max number of SACKS that we'll generate and process. It's safe
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* to increase this, although since:
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* size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
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* only four options will fit in a standard TCP header */
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#define TCP_NUM_SACKS 4
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struct tcp_request_sock_ops;
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struct tcp_request_sock {
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struct inet_request_sock req;
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const struct tcp_request_sock_ops *af_specific;
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struct skb_mstamp snt_synack; /* first SYNACK sent time */
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bool tfo_listener;
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u32 txhash;
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u32 rcv_isn;
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u32 snt_isn;
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u32 last_oow_ack_time; /* last SYNACK */
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u32 rcv_nxt; /* the ack # by SYNACK. For
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* FastOpen it's the seq#
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* after data-in-SYN.
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*/
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};
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static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
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{
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return (struct tcp_request_sock *)req;
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}
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struct tcp_sock {
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/* inet_connection_sock has to be the first member of tcp_sock */
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struct inet_connection_sock inet_conn;
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u16 tcp_header_len; /* Bytes of tcp header to send */
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u16 gso_segs; /* Max number of segs per GSO packet */
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/*
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* Header prediction flags
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* 0x5?10 << 16 + snd_wnd in net byte order
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*/
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__be32 pred_flags;
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/*
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* RFC793 variables by their proper names. This means you can
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* read the code and the spec side by side (and laugh ...)
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* See RFC793 and RFC1122. The RFC writes these in capitals.
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*/
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u64 bytes_received; /* RFC4898 tcpEStatsAppHCThruOctetsReceived
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* sum(delta(rcv_nxt)), or how many bytes
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* were acked.
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*/
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u32 segs_in; /* RFC4898 tcpEStatsPerfSegsIn
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* total number of segments in.
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*/
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u32 data_segs_in; /* RFC4898 tcpEStatsPerfDataSegsIn
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* total number of data segments in.
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*/
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u32 rcv_nxt; /* What we want to receive next */
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u32 copied_seq; /* Head of yet unread data */
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u32 rcv_wup; /* rcv_nxt on last window update sent */
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u32 snd_nxt; /* Next sequence we send */
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u32 segs_out; /* RFC4898 tcpEStatsPerfSegsOut
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* The total number of segments sent.
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*/
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u32 data_segs_out; /* RFC4898 tcpEStatsPerfDataSegsOut
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* total number of data segments sent.
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*/
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u64 bytes_acked; /* RFC4898 tcpEStatsAppHCThruOctetsAcked
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* sum(delta(snd_una)), or how many bytes
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* were acked.
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*/
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struct u64_stats_sync syncp; /* protects 64bit vars (cf tcp_get_info()) */
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u32 snd_una; /* First byte we want an ack for */
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u32 snd_sml; /* Last byte of the most recently transmitted small packet */
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u32 rcv_tstamp; /* timestamp of last received ACK (for keepalives) */
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u32 lsndtime; /* timestamp of last sent data packet (for restart window) */
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u32 last_oow_ack_time; /* timestamp of last out-of-window ACK */
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u32 tsoffset; /* timestamp offset */
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struct list_head tsq_node; /* anchor in tsq_tasklet.head list */
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unsigned long tsq_flags;
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/* Data for direct copy to user */
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struct {
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struct sk_buff_head prequeue;
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struct task_struct *task;
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struct msghdr *msg;
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int memory;
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int len;
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} ucopy;
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u32 snd_wl1; /* Sequence for window update */
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u32 snd_wnd; /* The window we expect to receive */
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u32 max_window; /* Maximal window ever seen from peer */
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u32 mss_cache; /* Cached effective mss, not including SACKS */
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u32 window_clamp; /* Maximal window to advertise */
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u32 rcv_ssthresh; /* Current window clamp */
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/* Information of the most recently (s)acked skb */
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struct tcp_rack {
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struct skb_mstamp mstamp; /* (Re)sent time of the skb */
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u8 advanced; /* mstamp advanced since last lost marking */
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u8 reord; /* reordering detected */
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} rack;
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u16 advmss; /* Advertised MSS */
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u8 rate_app_limited:1, /* rate_{delivered,interval_us} limited? */
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fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */
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unused:6;
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u8 nonagle : 4,/* Disable Nagle algorithm? */
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thin_lto : 1,/* Use linear timeouts for thin streams */
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thin_dupack : 1,/* Fast retransmit on first dupack */
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repair : 1,
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frto : 1;/* F-RTO (RFC5682) activated in CA_Loss */
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u8 repair_queue;
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u8 do_early_retrans:1,/* Enable RFC5827 early-retransmit */
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syn_data:1, /* SYN includes data */
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syn_fastopen:1, /* SYN includes Fast Open option */
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syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */
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syn_data_acked:1,/* data in SYN is acked by SYN-ACK */
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save_syn:1, /* Save headers of SYN packet */
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is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */
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u32 tlp_high_seq; /* snd_nxt at the time of TLP retransmit. */
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/* RTT measurement */
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u32 srtt_us; /* smoothed round trip time << 3 in usecs */
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u32 mdev_us; /* medium deviation */
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u32 mdev_max_us; /* maximal mdev for the last rtt period */
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u32 rttvar_us; /* smoothed mdev_max */
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u32 rtt_seq; /* sequence number to update rttvar */
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struct minmax rtt_min;
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u32 packets_out; /* Packets which are "in flight" */
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u32 retrans_out; /* Retransmitted packets out */
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u32 max_packets_out; /* max packets_out in last window */
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u32 max_packets_seq; /* right edge of max_packets_out flight */
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u16 urg_data; /* Saved octet of OOB data and control flags */
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u8 ecn_flags; /* ECN status bits. */
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u8 keepalive_probes; /* num of allowed keep alive probes */
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u32 reordering; /* Packet reordering metric. */
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u32 snd_up; /* Urgent pointer */
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/*
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* Options received (usually on last packet, some only on SYN packets).
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*/
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struct tcp_options_received rx_opt;
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/*
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* Slow start and congestion control (see also Nagle, and Karn & Partridge)
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*/
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u32 snd_ssthresh; /* Slow start size threshold */
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u32 snd_cwnd; /* Sending congestion window */
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u32 snd_cwnd_cnt; /* Linear increase counter */
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u32 snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
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u32 snd_cwnd_used;
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u32 snd_cwnd_stamp;
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u32 prior_cwnd; /* Congestion window at start of Recovery. */
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u32 prr_delivered; /* Number of newly delivered packets to
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* receiver in Recovery. */
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u32 prr_out; /* Total number of pkts sent during Recovery. */
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u32 delivered; /* Total data packets delivered incl. rexmits */
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u32 lost; /* Total data packets lost incl. rexmits */
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u32 app_limited; /* limited until "delivered" reaches this val */
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struct skb_mstamp first_tx_mstamp; /* start of window send phase */
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struct skb_mstamp delivered_mstamp; /* time we reached "delivered" */
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u32 rate_delivered; /* saved rate sample: packets delivered */
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u32 rate_interval_us; /* saved rate sample: time elapsed */
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u32 rcv_wnd; /* Current receiver window */
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u32 write_seq; /* Tail(+1) of data held in tcp send buffer */
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u32 notsent_lowat; /* TCP_NOTSENT_LOWAT */
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u32 pushed_seq; /* Last pushed seq, required to talk to windows */
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u32 lost_out; /* Lost packets */
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u32 sacked_out; /* SACK'd packets */
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u32 fackets_out; /* FACK'd packets */
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/* from STCP, retrans queue hinting */
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struct sk_buff* lost_skb_hint;
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struct sk_buff *retransmit_skb_hint;
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/* OOO segments go in this rbtree. Socket lock must be held. */
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struct rb_root out_of_order_queue;
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struct sk_buff *ooo_last_skb; /* cache rb_last(out_of_order_queue) */
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/* SACKs data, these 2 need to be together (see tcp_options_write) */
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struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
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struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
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struct tcp_sack_block recv_sack_cache[4];
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struct sk_buff *highest_sack; /* skb just after the highest
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* skb with SACKed bit set
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* (validity guaranteed only if
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* sacked_out > 0)
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*/
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int lost_cnt_hint;
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u32 retransmit_high; /* L-bits may be on up to this seqno */
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u32 prior_ssthresh; /* ssthresh saved at recovery start */
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u32 high_seq; /* snd_nxt at onset of congestion */
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u32 retrans_stamp; /* Timestamp of the last retransmit,
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* also used in SYN-SENT to remember stamp of
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* the first SYN. */
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u32 undo_marker; /* snd_una upon a new recovery episode. */
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int undo_retrans; /* number of undoable retransmissions. */
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u32 total_retrans; /* Total retransmits for entire connection */
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u32 urg_seq; /* Seq of received urgent pointer */
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unsigned int keepalive_time; /* time before keep alive takes place */
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unsigned int keepalive_intvl; /* time interval between keep alive probes */
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int linger2;
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/* Receiver side RTT estimation */
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struct {
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u32 rtt;
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u32 seq;
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u32 time;
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} rcv_rtt_est;
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/* Receiver queue space */
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struct {
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u32 space;
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u32 seq;
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u32 time;
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} rcvq_space;
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/* TCP-specific MTU probe information. */
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struct {
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u32 probe_seq_start;
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u32 probe_seq_end;
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} mtu_probe;
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u32 mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
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* while socket was owned by user.
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*/
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#ifdef CONFIG_TCP_MD5SIG
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/* TCP AF-Specific parts; only used by MD5 Signature support so far */
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const struct tcp_sock_af_ops *af_specific;
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/* TCP MD5 Signature Option information */
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struct tcp_md5sig_info __rcu *md5sig_info;
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#endif
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/* TCP fastopen related information */
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struct tcp_fastopen_request *fastopen_req;
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/* fastopen_rsk points to request_sock that resulted in this big
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* socket. Used to retransmit SYNACKs etc.
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*/
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struct request_sock *fastopen_rsk;
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u32 *saved_syn;
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};
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enum tsq_flags {
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TSQ_THROTTLED,
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TSQ_QUEUED,
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TCP_TSQ_DEFERRED, /* tcp_tasklet_func() found socket was owned */
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TCP_WRITE_TIMER_DEFERRED, /* tcp_write_timer() found socket was owned */
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TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */
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TCP_MTU_REDUCED_DEFERRED, /* tcp_v{4|6}_err() could not call
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* tcp_v{4|6}_mtu_reduced()
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*/
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};
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static inline struct tcp_sock *tcp_sk(const struct sock *sk)
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{
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return (struct tcp_sock *)sk;
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}
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struct tcp_timewait_sock {
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struct inet_timewait_sock tw_sk;
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#define tw_rcv_nxt tw_sk.__tw_common.skc_tw_rcv_nxt
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#define tw_snd_nxt tw_sk.__tw_common.skc_tw_snd_nxt
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u32 tw_rcv_wnd;
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u32 tw_ts_offset;
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u32 tw_ts_recent;
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/* The time we sent the last out-of-window ACK: */
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u32 tw_last_oow_ack_time;
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long tw_ts_recent_stamp;
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#ifdef CONFIG_TCP_MD5SIG
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struct tcp_md5sig_key *tw_md5_key;
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#endif
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};
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static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
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{
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return (struct tcp_timewait_sock *)sk;
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}
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static inline bool tcp_passive_fastopen(const struct sock *sk)
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{
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return (sk->sk_state == TCP_SYN_RECV &&
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tcp_sk(sk)->fastopen_rsk != NULL);
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}
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static inline void fastopen_queue_tune(struct sock *sk, int backlog)
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{
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struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
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int somaxconn = READ_ONCE(sock_net(sk)->core.sysctl_somaxconn);
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queue->fastopenq.max_qlen = min_t(unsigned int, backlog, somaxconn);
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}
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static inline void tcp_move_syn(struct tcp_sock *tp,
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struct request_sock *req)
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{
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tp->saved_syn = req->saved_syn;
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req->saved_syn = NULL;
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}
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static inline void tcp_saved_syn_free(struct tcp_sock *tp)
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{
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kfree(tp->saved_syn);
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tp->saved_syn = NULL;
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}
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#endif /* _LINUX_TCP_H */
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