include/linux/tcp.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   4  *              operating system.  INET is implemented using the  BSD Socket
   5  *              interface as the means of communication with the user level.
   6  *
   7  *              Definitions for the TCP protocol.
   8  *
   9  * Version:     @(#)tcp.h       1.0.2   04/28/93
  10  *
  11  * Author:      Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  */
  13 #ifndef _LINUX_TCP_H
  14 #define _LINUX_TCP_H
  15
  16
  17 #include <linux/skbuff.h>
  18 #include <linux/win_minmax.h>
  19 #include <net/sock.h>
  20 #include <net/inet_connection_sock.h>
  21 #include <net/inet_timewait_sock.h>
  22 #include <uapi/linux/tcp.h>
  23
  24 static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
  25 {
  26         return (struct tcphdr *)skb_transport_header(skb);
  27 }
  28
  29 static inline unsigned int __tcp_hdrlen(const struct tcphdr *th)
  30 {
  31         return th->doff * 4;
  32 }
  33
  34 static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
  35 {
  36         return __tcp_hdrlen(tcp_hdr(skb));
  37 }
  38
  39 static inline struct tcphdr *inner_tcp_hdr(const struct sk_buff *skb)
  40 {
  41         return (struct tcphdr *)skb_inner_transport_header(skb);
  42 }
  43
  44 static inline unsigned int inner_tcp_hdrlen(const struct sk_buff *skb)
  45 {
  46         return inner_tcp_hdr(skb)->doff * 4;
  47 }
  48
  49 /**
  50  * skb_tcp_all_headers - Returns size of all headers for a TCP packet
  51  * @skb: buffer
  52  *
  53  * Used in TX path, for a packet known to be a TCP one.
  54  *
  55  * if (skb_is_gso(skb)) {
  56  *         int hlen = skb_tcp_all_headers(skb);
  57  *         ...
  58  */
  59 static inline int skb_tcp_all_headers(const struct sk_buff *skb)
  60 {
  61         return skb_transport_offset(skb) + tcp_hdrlen(skb);
  62 }
  63
  64 /**
  65  * skb_inner_tcp_all_headers - Returns size of all headers for an encap TCP packet
  66  * @skb: buffer
  67  *
  68  * Used in TX path, for a packet known to be a TCP one.
  69  *
  70  * if (skb_is_gso(skb) && skb->encapsulation) {
  71  *         int hlen = skb_inner_tcp_all_headers(skb);
  72  *         ...
  73  */
  74 static inline int skb_inner_tcp_all_headers(const struct sk_buff *skb)
  75 {
  76         return skb_inner_transport_offset(skb) + inner_tcp_hdrlen(skb);
  77 }
  78
  79 static inline unsigned int tcp_optlen(const struct sk_buff *skb)
  80 {
  81         return (tcp_hdr(skb)->doff - 5) * 4;
  82 }
  83
  84 /* TCP Fast Open */
  85 #define TCP_FASTOPEN_COOKIE_MIN 4       /* Min Fast Open Cookie size in bytes */
  86 #define TCP_FASTOPEN_COOKIE_MAX 16      /* Max Fast Open Cookie size in bytes */
  87 #define TCP_FASTOPEN_COOKIE_SIZE 8      /* the size employed by this impl. */
  88
  89 /* TCP Fast Open Cookie as stored in memory */
  90 struct tcp_fastopen_cookie {
  91         __le64  val[DIV_ROUND_UP(TCP_FASTOPEN_COOKIE_MAX, sizeof(u64))];
  92         s8      len;
  93         bool    exp;    /* In RFC6994 experimental option format */
  94 };
  95
  96 /* This defines a selective acknowledgement block. */
  97 struct tcp_sack_block_wire {
  98         __be32  start_seq;
  99         __be32  end_seq;
 100 };
 101
 102 struct tcp_sack_block {
 103         u32     start_seq;
 104         u32     end_seq;
 105 };
 106
 107 /*These are used to set the sack_ok field in struct tcp_options_received */
 108 #define TCP_SACK_SEEN     (1 << 0)   /*1 = peer is SACK capable, */
 109 #define TCP_DSACK_SEEN    (1 << 2)   /*1 = DSACK was received from peer*/
 110
 111 struct tcp_options_received {
 112 /*      PAWS/RTTM data  */
 113         int     ts_recent_stamp;/* Time we stored ts_recent (for aging) */
 114         u32     ts_recent;      /* Time stamp to echo next              */
 115         u32     rcv_tsval;      /* Time stamp value                     */
 116         u32     rcv_tsecr;      /* Time stamp echo reply                */
 117         u16     saw_tstamp : 1, /* Saw TIMESTAMP on last packet         */
 118                 tstamp_ok : 1,  /* TIMESTAMP seen on SYN packet         */
 119                 dsack : 1,      /* D-SACK is scheduled                  */
 120                 wscale_ok : 1,  /* Wscale seen on SYN packet            */
 121                 sack_ok : 3,    /* SACK seen on SYN packet              */
 122                 smc_ok : 1,     /* SMC seen on SYN packet               */
 123                 snd_wscale : 4, /* Window scaling received from sender  */
 124                 rcv_wscale : 4; /* Window scaling to send to receiver   */
 125         u8      saw_unknown:1,  /* Received unknown option              */
 126                 unused:7;
 127         u8      num_sacks;      /* Number of SACK blocks                */
 128         u16     user_mss;       /* mss requested by user in ioctl       */
 129         u16     mss_clamp;      /* Maximal mss, negotiated at connection setup */
 130 };
 131
 132 static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
 133 {
 134         rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
 135         rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
 136 #if IS_ENABLED(CONFIG_SMC)
 137         rx_opt->smc_ok = 0;
 138 #endif
 139 }
 140
 141 /* This is the max number of SACKS that we'll generate and process. It's safe
 142  * to increase this, although since:
 143  *   size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
 144  * only four options will fit in a standard TCP header */
 145 #define TCP_NUM_SACKS 4
 146
 147 struct tcp_request_sock_ops;
 148
 149 struct tcp_request_sock {
 150         struct inet_request_sock        req;
 151         const struct tcp_request_sock_ops *af_specific;
 152         u64                             snt_synack; /* first SYNACK sent time */
 153         bool                            tfo_listener;
 154         bool                            is_mptcp;
 155         bool                            req_usec_ts;
 156 #if IS_ENABLED(CONFIG_MPTCP)
 157         bool                            drop_req;
 158 #endif
 159         u32                             txhash;
 160         u32                             rcv_isn;
 161         u32                             snt_isn;
 162         u32                             ts_off;
 163         u32                             last_oow_ack_time; /* last SYNACK */
 164         u32                             rcv_nxt; /* the ack # by SYNACK. For
 165                                                   * FastOpen it's the seq#
 166                                                   * after data-in-SYN.
 167                                                   */
 168         u8                              syn_tos;
 169 #ifdef CONFIG_TCP_AO
 170         u8                              ao_keyid;
 171         u8                              ao_rcv_next;
 172         bool                            used_tcp_ao;
 173 #endif
 174 };
 175
 176 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
 177 {
 178         return (struct tcp_request_sock *)req;
 179 }
 180
 181 static inline bool tcp_rsk_used_ao(const struct request_sock *req)
 182 {
 183 #ifndef CONFIG_TCP_AO
 184         return false;
 185 #else
 186         return tcp_rsk(req)->used_tcp_ao;
 187 #endif
 188 }
 189
 190 #define TCP_RMEM_TO_WIN_SCALE 8
 191
 192 struct tcp_sock {
 193         /* Cacheline organization can be found documented in
 194          * Documentation/networking/net_cachelines/tcp_sock.rst.
 195          * Please update the document when adding new fields.
 196          */
 197
 198         /* inet_connection_sock has to be the first member of tcp_sock */
 199         struct inet_connection_sock     inet_conn;
 200
 201         /* TX read-mostly hotpath cache lines */
 202         __cacheline_group_begin(tcp_sock_read_tx);
 203         u32     max_window;     /* Maximal window ever seen from peer   */
 204         u32     rcv_ssthresh;   /* Current window clamp                 */
 205         u32     reordering;     /* Packet reordering metric.            */
 206         u32     notsent_lowat;  /* TCP_NOTSENT_LOWAT */
 207         u16     gso_segs;       /* Max number of segs per GSO packet    */
 208         /* from STCP, retrans queue hinting */
 209         struct sk_buff *lost_skb_hint;
 210         struct sk_buff *retransmit_skb_hint;
 211         __cacheline_group_end(tcp_sock_read_tx);
 212
 213         /* TXRX read-mostly hotpath cache lines */
 214         __cacheline_group_begin(tcp_sock_read_txrx);
 215         u32     tsoffset;       /* timestamp offset */
 216         u32     snd_wnd;        /* The window we expect to receive      */
 217         u32     mss_cache;      /* Cached effective mss, not including SACKS */
 218         u32     snd_cwnd;       /* Sending congestion window            */
 219         u32     prr_out;        /* Total number of pkts sent during Recovery. */
 220         u32     lost_out;       /* Lost packets                 */
 221         u32     sacked_out;     /* SACK'd packets                       */
 222         u16     tcp_header_len; /* Bytes of tcp header to send          */
 223         u8      scaling_ratio;  /* see tcp_win_from_space() */
 224         u8      chrono_type : 2,        /* current chronograph type */
 225                 repair      : 1,
 226                 tcp_usec_ts : 1, /* TSval values in usec */
 227                 is_sack_reneg:1,    /* in recovery from loss with SACK reneg? */
 228                 is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */
 229         __cacheline_group_end(tcp_sock_read_txrx);
 230
 231         /* RX read-mostly hotpath cache lines */
 232         __cacheline_group_begin(tcp_sock_read_rx);
 233         u32     copied_seq;     /* Head of yet unread data */
 234         u32     rcv_tstamp;     /* timestamp of last received ACK (for keepalives) */
 235         u32     snd_wl1;        /* Sequence for window update           */
 236         u32     tlp_high_seq;   /* snd_nxt at the time of TLP */
 237         u32     rttvar_us;      /* smoothed mdev_max                    */
 238         u32     retrans_out;    /* Retransmitted packets out            */
 239         u16     advmss;         /* Advertised MSS                       */
 240         u16     urg_data;       /* Saved octet of OOB data and control flags */
 241         u32     lost;           /* Total data packets lost incl. rexmits */
 242         struct  minmax rtt_min;
 243         /* OOO segments go in this rbtree. Socket lock must be held. */
 244         struct rb_root  out_of_order_queue;
 245         u32     snd_ssthresh;   /* Slow start size threshold            */
 246         u8      recvmsg_inq : 1;/* Indicate # of bytes in queue upon recvmsg */
 247         __cacheline_group_end(tcp_sock_read_rx);
 248
 249         /* TX read-write hotpath cache lines */
 250         __cacheline_group_begin(tcp_sock_write_tx) ____cacheline_aligned;
 251         u32     segs_out;       /* RFC4898 tcpEStatsPerfSegsOut
 252                                  * The total number of segments sent.
 253                                  */
 254         u32     data_segs_out;  /* RFC4898 tcpEStatsPerfDataSegsOut
 255                                  * total number of data segments sent.
 256                                  */
 257         u64     bytes_sent;     /* RFC4898 tcpEStatsPerfHCDataOctetsOut
 258                                  * total number of data bytes sent.
 259                                  */
 260         u32     snd_sml;        /* Last byte of the most recently transmitted small packet */
 261         u32     chrono_start;   /* Start time in jiffies of a TCP chrono */
 262         u32     chrono_stat[3]; /* Time in jiffies for chrono_stat stats */
 263         u32     write_seq;      /* Tail(+1) of data held in tcp send buffer */
 264         u32     pushed_seq;     /* Last pushed seq, required to talk to windows */
 265         u32     lsndtime;       /* timestamp of last sent data packet (for restart window) */
 266         u32     mdev_us;        /* medium deviation                     */
 267         u32     rtt_seq;        /* sequence number to update rttvar     */
 268         u64     tcp_wstamp_ns;  /* departure time for next sent data packet */
 269         struct list_head tsorted_sent_queue; /* time-sorted sent but un-SACKed skbs */
 270         struct sk_buff *highest_sack;   /* skb just after the highest
 271                                          * skb with SACKed bit set
 272                                          * (validity guaranteed only if
 273                                          * sacked_out > 0)
 274                                          */
 275         u8      ecn_flags;      /* ECN status bits.                     */
 276         __cacheline_group_end(tcp_sock_write_tx);
 277
 278         /* TXRX read-write hotpath cache lines */
 279         __cacheline_group_begin(tcp_sock_write_txrx);
 280 /*
 281  *      Header prediction flags
 282  *      0x5?10 << 16 + snd_wnd in net byte order
 283  */
 284         __be32  pred_flags;
 285         u64     tcp_clock_cache; /* cache last tcp_clock_ns() (see tcp_mstamp_refresh()) */
 286         u64     tcp_mstamp;     /* most recent packet received/sent */
 287         u32     rcv_nxt;        /* What we want to receive next         */
 288         u32     snd_nxt;        /* Next sequence we send                */
 289         u32     snd_una;        /* First byte we want an ack for        */
 290         u32     window_clamp;   /* Maximal window to advertise          */
 291         u32     srtt_us;        /* smoothed round trip time << 3 in usecs */
 292         u32     packets_out;    /* Packets which are "in flight"        */
 293         u32     snd_up;         /* Urgent pointer               */
 294         u32     delivered;      /* Total data packets delivered incl. rexmits */
 295         u32     delivered_ce;   /* Like the above but only ECE marked packets */
 296         u32     app_limited;    /* limited until "delivered" reaches this val */
 297         u32     rcv_wnd;        /* Current receiver window              */
 298 /*
 299  *      Options received (usually on last packet, some only on SYN packets).
 300  */
 301         struct tcp_options_received rx_opt;
 302         u8      nonagle     : 4,/* Disable Nagle algorithm?             */
 303                 rate_app_limited:1;  /* rate_{delivered,interval_us} limited? */
 304         __cacheline_group_end(tcp_sock_write_txrx);
 305
 306         /* RX read-write hotpath cache lines */
 307         __cacheline_group_begin(tcp_sock_write_rx) __aligned(8);
 308         u64     bytes_received;
 309                                 /* RFC4898 tcpEStatsAppHCThruOctetsReceived
 310                                  * sum(delta(rcv_nxt)), or how many bytes
 311                                  * were acked.
 312                                  */
 313         u32     segs_in;        /* RFC4898 tcpEStatsPerfSegsIn
 314                                  * total number of segments in.
 315                                  */
 316         u32     data_segs_in;   /* RFC4898 tcpEStatsPerfDataSegsIn
 317                                  * total number of data segments in.
 318                                  */
 319         u32     rcv_wup;        /* rcv_nxt on last window update sent   */
 320         u32     max_packets_out;  /* max packets_out in last window */
 321         u32     cwnd_usage_seq;  /* right edge of cwnd usage tracking flight */
 322         u32     rate_delivered;    /* saved rate sample: packets delivered */
 323         u32     rate_interval_us;  /* saved rate sample: time elapsed */
 324         u32     rcv_rtt_last_tsecr;
 325         u64     first_tx_mstamp;  /* start of window send phase */
 326         u64     delivered_mstamp; /* time we reached "delivered" */
 327         u64     bytes_acked;    /* RFC4898 tcpEStatsAppHCThruOctetsAcked
 328                                  * sum(delta(snd_una)), or how many bytes
 329                                  * were acked.
 330                                  */
 331         struct {
 332                 u32     rtt_us;
 333                 u32     seq;
 334                 u64     time;
 335         } rcv_rtt_est;
 336 /* Receiver queue space */
 337         struct {
 338                 u32     space;
 339                 u32     seq;
 340                 u64     time;
 341         } rcvq_space;
 342         __cacheline_group_end(tcp_sock_write_rx);
 343         /* End of Hot Path */
 344
 345 /*
 346  *      RFC793 variables by their proper names. This means you can
 347  *      read the code and the spec side by side (and laugh ...)
 348  *      See RFC793 and RFC1122. The RFC writes these in capitals.
 349  */
 350         u32     dsack_dups;     /* RFC4898 tcpEStatsStackDSACKDups
 351                                  * total number of DSACK blocks received
 352                                  */
 353         u32     compressed_ack_rcv_nxt;
 354         struct list_head tsq_node; /* anchor in tsq_tasklet.head list */
 355
 356         /* Information of the most recently (s)acked skb */
 357         struct tcp_rack {
 358                 u64 mstamp; /* (Re)sent time of the skb */
 359                 u32 rtt_us;  /* Associated RTT */
 360                 u32 end_seq; /* Ending TCP sequence of the skb */
 361                 u32 last_delivered; /* tp->delivered at last reo_wnd adj */
 362                 u8 reo_wnd_steps;   /* Allowed reordering window */
 363 #define TCP_RACK_RECOVERY_THRESH 16
 364                 u8 reo_wnd_persist:5, /* No. of recovery since last adj */
 365                    dsack_seen:1, /* Whether DSACK seen after last adj */
 366                    advanced:1;   /* mstamp advanced since last lost marking */
 367         } rack;
 368         u8      compressed_ack;
 369         u8      dup_ack_counter:2,
 370                 tlp_retrans:1,  /* TLP is a retransmission */
 371                 unused:5;
 372         u8      thin_lto    : 1,/* Use linear timeouts for thin streams */
 373                 fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */
 374                 fastopen_no_cookie:1, /* Allow send/recv SYN+data without a cookie */
 375                 fastopen_client_fail:2, /* reason why fastopen failed */
 376                 frto        : 1;/* F-RTO (RFC5682) activated in CA_Loss */
 377         u8      repair_queue;
 378         u8      save_syn:2,     /* Save headers of SYN packet */
 379                 syn_data:1,     /* SYN includes data */
 380                 syn_fastopen:1, /* SYN includes Fast Open option */
 381                 syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */
 382                 syn_fastopen_ch:1, /* Active TFO re-enabling probe */
 383                 syn_data_acked:1;/* data in SYN is acked by SYN-ACK */
 384
 385         u8      keepalive_probes; /* num of allowed keep alive probes   */
 386         u32     tcp_tx_delay;   /* delay (in usec) added to TX packets */
 387
 388 /* RTT measurement */
 389         u32     mdev_max_us;    /* maximal mdev for the last rtt period */
 390
 391         u32     reord_seen;     /* number of data packet reordering events */
 392
 393 /*
 394  *      Slow start and congestion control (see also Nagle, and Karn & Partridge)
 395  */
 396         u32     snd_cwnd_cnt;   /* Linear increase counter              */
 397         u32     snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
 398         u32     snd_cwnd_used;
 399         u32     snd_cwnd_stamp;
 400         u32     prior_cwnd;     /* cwnd right before starting loss recovery */
 401         u32     prr_delivered;  /* Number of newly delivered packets to
 402                                  * receiver in Recovery. */
 403         u32     last_oow_ack_time;  /* timestamp of last out-of-window ACK */
 404
 405         struct hrtimer  pacing_timer;
 406         struct hrtimer  compressed_ack_timer;
 407
 408         struct sk_buff  *ooo_last_skb; /* cache rb_last(out_of_order_queue) */
 409
 410         /* SACKs data, these 2 need to be together (see tcp_options_write) */
 411         struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
 412         struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
 413
 414         struct tcp_sack_block recv_sack_cache[4];
 415
 416         int     lost_cnt_hint;
 417
 418         u32     prior_ssthresh; /* ssthresh saved at recovery start     */
 419         u32     high_seq;       /* snd_nxt at onset of congestion       */
 420
 421         u32     retrans_stamp;  /* Timestamp of the last retransmit,
 422                                  * also used in SYN-SENT to remember stamp of
 423                                  * the first SYN. */
 424         u32     undo_marker;    /* snd_una upon a new recovery episode. */
 425         int     undo_retrans;   /* number of undoable retransmissions. */
 426         u64     bytes_retrans;  /* RFC4898 tcpEStatsPerfOctetsRetrans
 427                                  * Total data bytes retransmitted
 428                                  */
 429         u32     total_retrans;  /* Total retransmits for entire connection */
 430         u32     rto_stamp;      /* Start time (ms) of last CA_Loss recovery */
 431         u16     total_rto;      /* Total number of RTO timeouts, including
 432                                  * SYN/SYN-ACK and recurring timeouts.
 433                                  */
 434         u16     total_rto_recoveries;   /* Total number of RTO recoveries,
 435                                          * including any unfinished recovery.
 436                                          */
 437         u32     total_rto_time; /* ms spent in (completed) RTO recoveries. */
 438
 439         u32     urg_seq;        /* Seq of received urgent pointer */
 440         unsigned int            keepalive_time;   /* time before keep alive takes place */
 441         unsigned int            keepalive_intvl;  /* time interval between keep alive probes */
 442
 443         int                     linger2;
 444
 445
 446 /* Sock_ops bpf program related variables */
 447 #ifdef CONFIG_BPF
 448         u8      bpf_sock_ops_cb_flags;  /* Control calling BPF programs
 449                                          * values defined in uapi/linux/tcp.h
 450                                          */
 451         u8      bpf_chg_cc_inprogress:1; /* In the middle of
 452                                           * bpf_setsockopt(TCP_CONGESTION),
 453                                           * it is to avoid the bpf_tcp_cc->init()
 454                                           * to recur itself by calling
 455                                           * bpf_setsockopt(TCP_CONGESTION, "itself").
 456                                           */
 457 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) (TP->bpf_sock_ops_cb_flags & ARG)
 458 #else
 459 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) 0
 460 #endif
 461
 462         u16 timeout_rehash;     /* Timeout-triggered rehash attempts */
 463
 464         u32 rcv_ooopack; /* Received out-of-order packets, for tcpinfo */
 465
 466 /* TCP-specific MTU probe information. */
 467         struct {
 468                 u32               probe_seq_start;
 469                 u32               probe_seq_end;
 470         } mtu_probe;
 471         u32     plb_rehash;     /* PLB-triggered rehash attempts */
 472         u32     mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
 473                            * while socket was owned by user.
 474                            */
 475 #if IS_ENABLED(CONFIG_MPTCP)
 476         bool    is_mptcp;
 477 #endif
 478 #if IS_ENABLED(CONFIG_SMC)
 479         bool    syn_smc;        /* SYN includes SMC */
 480         bool    (*smc_hs_congested)(const struct sock *sk);
 481 #endif
 482
 483 #if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
 484 /* TCP AF-Specific parts; only used by TCP-AO/MD5 Signature support so far */
 485         const struct tcp_sock_af_ops    *af_specific;
 486
 487 #ifdef CONFIG_TCP_MD5SIG
 488 /* TCP MD5 Signature Option information */
 489         struct tcp_md5sig_info  __rcu *md5sig_info;
 490 #endif
 491 #ifdef CONFIG_TCP_AO
 492         struct tcp_ao_info      __rcu *ao_info;
 493 #endif
 494 #endif
 495
 496 /* TCP fastopen related information */
 497         struct tcp_fastopen_request *fastopen_req;
 498         /* fastopen_rsk points to request_sock that resulted in this big
 499          * socket. Used to retransmit SYNACKs etc.
 500          */
 501         struct request_sock __rcu *fastopen_rsk;
 502         struct saved_syn *saved_syn;
 503 };
 504
 505 enum tsq_enum {
 506         TSQ_THROTTLED,
 507         TSQ_QUEUED,
 508         TCP_TSQ_DEFERRED,          /* tcp_tasklet_func() found socket was owned */
 509         TCP_WRITE_TIMER_DEFERRED,  /* tcp_write_timer() found socket was owned */
 510         TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */
 511         TCP_MTU_REDUCED_DEFERRED,  /* tcp_v{4|6}_err() could not call
 512                                     * tcp_v{4|6}_mtu_reduced()
 513                                     */
 514         TCP_ACK_DEFERRED,          /* TX pure ack is deferred */
 515 };
 516
 517 enum tsq_flags {
 518         TSQF_THROTTLED                  = BIT(TSQ_THROTTLED),
 519         TSQF_QUEUED                     = BIT(TSQ_QUEUED),
 520         TCPF_TSQ_DEFERRED               = BIT(TCP_TSQ_DEFERRED),
 521         TCPF_WRITE_TIMER_DEFERRED       = BIT(TCP_WRITE_TIMER_DEFERRED),
 522         TCPF_DELACK_TIMER_DEFERRED      = BIT(TCP_DELACK_TIMER_DEFERRED),
 523         TCPF_MTU_REDUCED_DEFERRED       = BIT(TCP_MTU_REDUCED_DEFERRED),
 524         TCPF_ACK_DEFERRED               = BIT(TCP_ACK_DEFERRED),
 525 };
 526
 527 #define tcp_sk(ptr) container_of_const(ptr, struct tcp_sock, inet_conn.icsk_inet.sk)
 528
 529 /* Variant of tcp_sk() upgrading a const sock to a read/write tcp socket.
 530  * Used in context of (lockless) tcp listeners.
 531  */
 532 #define tcp_sk_rw(ptr) container_of(ptr, struct tcp_sock, inet_conn.icsk_inet.sk)
 533
 534 struct tcp_timewait_sock {
 535         struct inet_timewait_sock tw_sk;
 536 #define tw_rcv_nxt tw_sk.__tw_common.skc_tw_rcv_nxt
 537 #define tw_snd_nxt tw_sk.__tw_common.skc_tw_snd_nxt
 538         u32                       tw_rcv_wnd;
 539         u32                       tw_ts_offset;
 540         u32                       tw_ts_recent;
 541
 542         /* The time we sent the last out-of-window ACK: */
 543         u32                       tw_last_oow_ack_time;
 544
 545         int                       tw_ts_recent_stamp;
 546         u32                       tw_tx_delay;
 547 #ifdef CONFIG_TCP_MD5SIG
 548         struct tcp_md5sig_key     *tw_md5_key;
 549 #endif
 550 #ifdef CONFIG_TCP_AO
 551         struct tcp_ao_info      __rcu *ao_info;
 552 #endif
 553 };
 554
 555 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
 556 {
 557         return (struct tcp_timewait_sock *)sk;
 558 }
 559
 560 static inline bool tcp_passive_fastopen(const struct sock *sk)
 561 {
 562         return sk->sk_state == TCP_SYN_RECV &&
 563                rcu_access_pointer(tcp_sk(sk)->fastopen_rsk) != NULL;
 564 }
 565
 566 static inline void fastopen_queue_tune(struct sock *sk, int backlog)
 567 {
 568         struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
 569         int somaxconn = READ_ONCE(sock_net(sk)->core.sysctl_somaxconn);
 570
 571         WRITE_ONCE(queue->fastopenq.max_qlen, min_t(unsigned int, backlog, somaxconn));
 572 }
 573
 574 static inline void tcp_move_syn(struct tcp_sock *tp,
 575                                 struct request_sock *req)
 576 {
 577         tp->saved_syn = req->saved_syn;
 578         req->saved_syn = NULL;
 579 }
 580
 581 static inline void tcp_saved_syn_free(struct tcp_sock *tp)
 582 {
 583         kfree(tp->saved_syn);
 584         tp->saved_syn = NULL;
 585 }
 586
 587 static inline u32 tcp_saved_syn_len(const struct saved_syn *saved_syn)
 588 {
 589         return saved_syn->mac_hdrlen + saved_syn->network_hdrlen +
 590                 saved_syn->tcp_hdrlen;
 591 }
 592
 593 struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk,
 594                                                const struct sk_buff *orig_skb,
 595                                                const struct sk_buff *ack_skb);
 596
 597 static inline u16 tcp_mss_clamp(const struct tcp_sock *tp, u16 mss)
 598 {
 599         /* We use READ_ONCE() here because socket might not be locked.
 600          * This happens for listeners.
 601          */
 602         u16 user_mss = READ_ONCE(tp->rx_opt.user_mss);
 603
 604         return (user_mss && user_mss < mss) ? user_mss : mss;
 605 }
 606
 607 int tcp_skb_shift(struct sk_buff *to, struct sk_buff *from, int pcount,
 608                   int shiftlen);
 609
 610 void __tcp_sock_set_cork(struct sock *sk, bool on);
 611 void tcp_sock_set_cork(struct sock *sk, bool on);
 612 int tcp_sock_set_keepcnt(struct sock *sk, int val);
 613 int tcp_sock_set_keepidle_locked(struct sock *sk, int val);
 614 int tcp_sock_set_keepidle(struct sock *sk, int val);
 615 int tcp_sock_set_keepintvl(struct sock *sk, int val);
 616 void __tcp_sock_set_nodelay(struct sock *sk, bool on);
 617 void tcp_sock_set_nodelay(struct sock *sk);
 618 void tcp_sock_set_quickack(struct sock *sk, int val);
 619 int tcp_sock_set_syncnt(struct sock *sk, int val);
 620 int tcp_sock_set_user_timeout(struct sock *sk, int val);
 621
 622 static inline bool dst_tcp_usec_ts(const struct dst_entry *dst)
 623 {
 624         return dst_feature(dst, RTAX_FEATURE_TCP_USEC_TS);
 625 }
 626
 627 #endif  /* _LINUX_TCP_H */