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TOMOYO Linux Cross Reference
Linux/include/linux/tcp.h

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  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         /* timestamp of last sent data packet (for restart window) */
204         u32     max_window;     /* Maximal window ever seen from peer   */
205         u32     rcv_ssthresh;   /* Current window clamp                 */
206         u32     reordering;     /* Packet reordering metric.            */
207         u32     notsent_lowat;  /* TCP_NOTSENT_LOWAT */
208         u16     gso_segs;       /* Max number of segs per GSO packet    */
209         /* from STCP, retrans queue hinting */
210         struct sk_buff *lost_skb_hint;
211         struct sk_buff *retransmit_skb_hint;
212         __cacheline_group_end(tcp_sock_read_tx);
213 
214         /* TXRX read-mostly hotpath cache lines */
215         __cacheline_group_begin(tcp_sock_read_txrx);
216         u32     tsoffset;       /* timestamp offset */
217         u32     snd_wnd;        /* The window we expect to receive      */
218         u32     mss_cache;      /* Cached effective mss, not including SACKS */
219         u32     snd_cwnd;       /* Sending congestion window            */
220         u32     prr_out;        /* Total number of pkts sent during Recovery. */
221         u32     lost_out;       /* Lost packets                 */
222         u32     sacked_out;     /* SACK'd packets                       */
223         u16     tcp_header_len; /* Bytes of tcp header to send          */
224         u8      scaling_ratio;  /* see tcp_win_from_space() */
225         u8      chrono_type : 2,        /* current chronograph type */
226                 repair      : 1,
227                 tcp_usec_ts : 1, /* TSval values in usec */
228                 is_sack_reneg:1,    /* in recovery from loss with SACK reneg? */
229                 is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */
230         __cacheline_group_end(tcp_sock_read_txrx);
231 
232         /* RX read-mostly hotpath cache lines */
233         __cacheline_group_begin(tcp_sock_read_rx);
234         u32     copied_seq;     /* Head of yet unread data */
235         u32     rcv_tstamp;     /* timestamp of last received ACK (for keepalives) */
236         u32     snd_wl1;        /* Sequence for window update           */
237         u32     tlp_high_seq;   /* snd_nxt at the time of TLP */
238         u32     rttvar_us;      /* smoothed mdev_max                    */
239         u32     retrans_out;    /* Retransmitted packets out            */
240         u16     advmss;         /* Advertised MSS                       */
241         u16     urg_data;       /* Saved octet of OOB data and control flags */
242         u32     lost;           /* Total data packets lost incl. rexmits */
243         struct  minmax rtt_min;
244         /* OOO segments go in this rbtree. Socket lock must be held. */
245         struct rb_root  out_of_order_queue;
246         u32     snd_ssthresh;   /* Slow start size threshold            */
247         u8      recvmsg_inq : 1;/* Indicate # of bytes in queue upon recvmsg */
248         __cacheline_group_end(tcp_sock_read_rx);
249 
250         /* TX read-write hotpath cache lines */
251         __cacheline_group_begin(tcp_sock_write_tx) ____cacheline_aligned;
252         u32     segs_out;       /* RFC4898 tcpEStatsPerfSegsOut
253                                  * The total number of segments sent.
254                                  */
255         u32     data_segs_out;  /* RFC4898 tcpEStatsPerfDataSegsOut
256                                  * total number of data segments sent.
257                                  */
258         u64     bytes_sent;     /* RFC4898 tcpEStatsPerfHCDataOctetsOut
259                                  * total number of data bytes sent.
260                                  */
261         u32     snd_sml;        /* Last byte of the most recently transmitted small packet */
262         u32     chrono_start;   /* Start time in jiffies of a TCP chrono */
263         u32     chrono_stat[3]; /* Time in jiffies for chrono_stat stats */
264         u32     write_seq;      /* Tail(+1) of data held in tcp send buffer */
265         u32     pushed_seq;     /* Last pushed seq, required to talk to windows */
266         u32     lsndtime;
267         u32     mdev_us;        /* medium deviation                     */
268         u32     rtt_seq;        /* sequence number to update rttvar     */
269         u64     tcp_wstamp_ns;  /* departure time for next sent data packet */
270         struct list_head tsorted_sent_queue; /* time-sorted sent but un-SACKed skbs */
271         struct sk_buff *highest_sack;   /* skb just after the highest
272                                          * skb with SACKed bit set
273                                          * (validity guaranteed only if
274                                          * sacked_out > 0)
275                                          */
276         u8      ecn_flags;      /* ECN status bits.                     */
277         __cacheline_group_end(tcp_sock_write_tx);
278 
279         /* TXRX read-write hotpath cache lines */
280         __cacheline_group_begin(tcp_sock_write_txrx);
281 /*
282  *      Header prediction flags
283  *      0x5?10 << 16 + snd_wnd in net byte order
284  */
285         __be32  pred_flags;
286         u64     tcp_clock_cache; /* cache last tcp_clock_ns() (see tcp_mstamp_refresh()) */
287         u64     tcp_mstamp;     /* most recent packet received/sent */
288         u32     rcv_nxt;        /* What we want to receive next         */
289         u32     snd_nxt;        /* Next sequence we send                */
290         u32     snd_una;        /* First byte we want an ack for        */
291         u32     window_clamp;   /* Maximal window to advertise          */
292         u32     srtt_us;        /* smoothed round trip time << 3 in usecs */
293         u32     packets_out;    /* Packets which are "in flight"        */
294         u32     snd_up;         /* Urgent pointer               */
295         u32     delivered;      /* Total data packets delivered incl. rexmits */
296         u32     delivered_ce;   /* Like the above but only ECE marked packets */
297         u32     app_limited;    /* limited until "delivered" reaches this val */
298         u32     rcv_wnd;        /* Current receiver window              */
299 /*
300  *      Options received (usually on last packet, some only on SYN packets).
301  */
302         struct tcp_options_received rx_opt;
303         u8      nonagle     : 4,/* Disable Nagle algorithm?             */
304                 rate_app_limited:1;  /* rate_{delivered,interval_us} limited? */
305         __cacheline_group_end(tcp_sock_write_txrx);
306 
307         /* RX read-write hotpath cache lines */
308         __cacheline_group_begin(tcp_sock_write_rx) __aligned(8);
309         u64     bytes_received;
310                                 /* RFC4898 tcpEStatsAppHCThruOctetsReceived
311                                  * sum(delta(rcv_nxt)), or how many bytes
312                                  * were acked.
313                                  */
314         u32     segs_in;        /* RFC4898 tcpEStatsPerfSegsIn
315                                  * total number of segments in.
316                                  */
317         u32     data_segs_in;   /* RFC4898 tcpEStatsPerfDataSegsIn
318                                  * total number of data segments in.
319                                  */
320         u32     rcv_wup;        /* rcv_nxt on last window update sent   */
321         u32     max_packets_out;  /* max packets_out in last window */
322         u32     cwnd_usage_seq;  /* right edge of cwnd usage tracking flight */
323         u32     rate_delivered;    /* saved rate sample: packets delivered */
324         u32     rate_interval_us;  /* saved rate sample: time elapsed */
325         u32     rcv_rtt_last_tsecr;
326         u64     first_tx_mstamp;  /* start of window send phase */
327         u64     delivered_mstamp; /* time we reached "delivered" */
328         u64     bytes_acked;    /* RFC4898 tcpEStatsAppHCThruOctetsAcked
329                                  * sum(delta(snd_una)), or how many bytes
330                                  * were acked.
331                                  */
332         struct {
333                 u32     rtt_us;
334                 u32     seq;
335                 u64     time;
336         } rcv_rtt_est;
337 /* Receiver queue space */
338         struct {
339                 u32     space;
340                 u32     seq;
341                 u64     time;
342         } rcvq_space;
343         __cacheline_group_end(tcp_sock_write_rx);
344         /* End of Hot Path */
345 
346 /*
347  *      RFC793 variables by their proper names. This means you can
348  *      read the code and the spec side by side (and laugh ...)
349  *      See RFC793 and RFC1122. The RFC writes these in capitals.
350  */
351         u32     dsack_dups;     /* RFC4898 tcpEStatsStackDSACKDups
352                                  * total number of DSACK blocks received
353                                  */
354         u32     compressed_ack_rcv_nxt;
355         struct list_head tsq_node; /* anchor in tsq_tasklet.head list */
356 
357         /* Information of the most recently (s)acked skb */
358         struct tcp_rack {
359                 u64 mstamp; /* (Re)sent time of the skb */
360                 u32 rtt_us;  /* Associated RTT */
361                 u32 end_seq; /* Ending TCP sequence of the skb */
362                 u32 last_delivered; /* tp->delivered at last reo_wnd adj */
363                 u8 reo_wnd_steps;   /* Allowed reordering window */
364 #define TCP_RACK_RECOVERY_THRESH 16
365                 u8 reo_wnd_persist:5, /* No. of recovery since last adj */
366                    dsack_seen:1, /* Whether DSACK seen after last adj */
367                    advanced:1;   /* mstamp advanced since last lost marking */
368         } rack;
369         u8      compressed_ack;
370         u8      dup_ack_counter:2,
371                 tlp_retrans:1,  /* TLP is a retransmission */
372                 unused:5;
373         u8      thin_lto    : 1,/* Use linear timeouts for thin streams */
374                 fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */
375                 fastopen_no_cookie:1, /* Allow send/recv SYN+data without a cookie */
376                 fastopen_client_fail:2, /* reason why fastopen failed */
377                 frto        : 1;/* F-RTO (RFC5682) activated in CA_Loss */
378         u8      repair_queue;
379         u8      save_syn:2,     /* Save headers of SYN packet */
380                 syn_data:1,     /* SYN includes data */
381                 syn_fastopen:1, /* SYN includes Fast Open option */
382                 syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */
383                 syn_fastopen_ch:1, /* Active TFO re-enabling probe */
384                 syn_data_acked:1;/* data in SYN is acked by SYN-ACK */
385 
386         u8      keepalive_probes; /* num of allowed keep alive probes   */
387         u32     tcp_tx_delay;   /* delay (in usec) added to TX packets */
388 
389 /* RTT measurement */
390         u32     mdev_max_us;    /* maximal mdev for the last rtt period */
391 
392         u32     reord_seen;     /* number of data packet reordering events */
393 
394 /*
395  *      Slow start and congestion control (see also Nagle, and Karn & Partridge)
396  */
397         u32     snd_cwnd_cnt;   /* Linear increase counter              */
398         u32     snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
399         u32     snd_cwnd_used;
400         u32     snd_cwnd_stamp;
401         u32     prior_cwnd;     /* cwnd right before starting loss recovery */
402         u32     prr_delivered;  /* Number of newly delivered packets to
403                                  * receiver in Recovery. */
404         u32     last_oow_ack_time;  /* timestamp of last out-of-window ACK */
405 
406         struct hrtimer  pacing_timer;
407         struct hrtimer  compressed_ack_timer;
408 
409         struct sk_buff  *ooo_last_skb; /* cache rb_last(out_of_order_queue) */
410 
411         /* SACKs data, these 2 need to be together (see tcp_options_write) */
412         struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
413         struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
414 
415         struct tcp_sack_block recv_sack_cache[4];
416 
417         int     lost_cnt_hint;
418 
419         u32     prior_ssthresh; /* ssthresh saved at recovery start     */
420         u32     high_seq;       /* snd_nxt at onset of congestion       */
421 
422         u32     retrans_stamp;  /* Timestamp of the last retransmit,
423                                  * also used in SYN-SENT to remember stamp of
424                                  * the first SYN. */
425         u32     undo_marker;    /* snd_una upon a new recovery episode. */
426         int     undo_retrans;   /* number of undoable retransmissions. */
427         u64     bytes_retrans;  /* RFC4898 tcpEStatsPerfOctetsRetrans
428                                  * Total data bytes retransmitted
429                                  */
430         u32     total_retrans;  /* Total retransmits for entire connection */
431         u32     rto_stamp;      /* Start time (ms) of last CA_Loss recovery */
432         u16     total_rto;      /* Total number of RTO timeouts, including
433                                  * SYN/SYN-ACK and recurring timeouts.
434                                  */
435         u16     total_rto_recoveries;   /* Total number of RTO recoveries,
436                                          * including any unfinished recovery.
437                                          */
438         u32     total_rto_time; /* ms spent in (completed) RTO recoveries. */
439 
440         u32     urg_seq;        /* Seq of received urgent pointer */
441         unsigned int            keepalive_time;   /* time before keep alive takes place */
442         unsigned int            keepalive_intvl;  /* time interval between keep alive probes */
443 
444         int                     linger2;
445 
446 
447 /* Sock_ops bpf program related variables */
448 #ifdef CONFIG_BPF
449         u8      bpf_sock_ops_cb_flags;  /* Control calling BPF programs
450                                          * values defined in uapi/linux/tcp.h
451                                          */
452         u8      bpf_chg_cc_inprogress:1; /* In the middle of
453                                           * bpf_setsockopt(TCP_CONGESTION),
454                                           * it is to avoid the bpf_tcp_cc->init()
455                                           * to recur itself by calling
456                                           * bpf_setsockopt(TCP_CONGESTION, "itself").
457                                           */
458 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) (TP->bpf_sock_ops_cb_flags & ARG)
459 #else
460 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) 0
461 #endif
462 
463         u16 timeout_rehash;     /* Timeout-triggered rehash attempts */
464 
465         u32 rcv_ooopack; /* Received out-of-order packets, for tcpinfo */
466 
467 /* TCP-specific MTU probe information. */
468         struct {
469                 u32               probe_seq_start;
470                 u32               probe_seq_end;
471         } mtu_probe;
472         u32     plb_rehash;     /* PLB-triggered rehash attempts */
473         u32     mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
474                            * while socket was owned by user.
475                            */
476 #if IS_ENABLED(CONFIG_MPTCP)
477         bool    is_mptcp;
478 #endif
479 #if IS_ENABLED(CONFIG_SMC)
480         bool    syn_smc;        /* SYN includes SMC */
481         bool    (*smc_hs_congested)(const struct sock *sk);
482 #endif
483 
484 #if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
485 /* TCP AF-Specific parts; only used by TCP-AO/MD5 Signature support so far */
486         const struct tcp_sock_af_ops    *af_specific;
487 
488 #ifdef CONFIG_TCP_MD5SIG
489 /* TCP MD5 Signature Option information */
490         struct tcp_md5sig_info  __rcu *md5sig_info;
491 #endif
492 #ifdef CONFIG_TCP_AO
493         struct tcp_ao_info      __rcu *ao_info;
494 #endif
495 #endif
496 
497 /* TCP fastopen related information */
498         struct tcp_fastopen_request *fastopen_req;
499         /* fastopen_rsk points to request_sock that resulted in this big
500          * socket. Used to retransmit SYNACKs etc.
501          */
502         struct request_sock __rcu *fastopen_rsk;
503         struct saved_syn *saved_syn;
504 };
505 
506 enum tsq_enum {
507         TSQ_THROTTLED,
508         TSQ_QUEUED,
509         TCP_TSQ_DEFERRED,          /* tcp_tasklet_func() found socket was owned */
510         TCP_WRITE_TIMER_DEFERRED,  /* tcp_write_timer() found socket was owned */
511         TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */
512         TCP_MTU_REDUCED_DEFERRED,  /* tcp_v{4|6}_err() could not call
513                                     * tcp_v{4|6}_mtu_reduced()
514                                     */
515         TCP_ACK_DEFERRED,          /* TX pure ack is deferred */
516 };
517 
518 enum tsq_flags {
519         TSQF_THROTTLED                  = BIT(TSQ_THROTTLED),
520         TSQF_QUEUED                     = BIT(TSQ_QUEUED),
521         TCPF_TSQ_DEFERRED               = BIT(TCP_TSQ_DEFERRED),
522         TCPF_WRITE_TIMER_DEFERRED       = BIT(TCP_WRITE_TIMER_DEFERRED),
523         TCPF_DELACK_TIMER_DEFERRED      = BIT(TCP_DELACK_TIMER_DEFERRED),
524         TCPF_MTU_REDUCED_DEFERRED       = BIT(TCP_MTU_REDUCED_DEFERRED),
525         TCPF_ACK_DEFERRED               = BIT(TCP_ACK_DEFERRED),
526 };
527 
528 #define tcp_sk(ptr) container_of_const(ptr, struct tcp_sock, inet_conn.icsk_inet.sk)
529 
530 /* Variant of tcp_sk() upgrading a const sock to a read/write tcp socket.
531  * Used in context of (lockless) tcp listeners.
532  */
533 #define tcp_sk_rw(ptr) container_of(ptr, struct tcp_sock, inet_conn.icsk_inet.sk)
534 
535 struct tcp_timewait_sock {
536         struct inet_timewait_sock tw_sk;
537 #define tw_rcv_nxt tw_sk.__tw_common.skc_tw_rcv_nxt
538 #define tw_snd_nxt tw_sk.__tw_common.skc_tw_snd_nxt
539         u32                       tw_rcv_wnd;
540         u32                       tw_ts_offset;
541         u32                       tw_ts_recent;
542 
543         /* The time we sent the last out-of-window ACK: */
544         u32                       tw_last_oow_ack_time;
545 
546         int                       tw_ts_recent_stamp;
547         u32                       tw_tx_delay;
548 #ifdef CONFIG_TCP_MD5SIG
549         struct tcp_md5sig_key     *tw_md5_key;
550 #endif
551 #ifdef CONFIG_TCP_AO
552         struct tcp_ao_info      __rcu *ao_info;
553 #endif
554 };
555 
556 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
557 {
558         return (struct tcp_timewait_sock *)sk;
559 }
560 
561 static inline bool tcp_passive_fastopen(const struct sock *sk)
562 {
563         return sk->sk_state == TCP_SYN_RECV &&
564                rcu_access_pointer(tcp_sk(sk)->fastopen_rsk) != NULL;
565 }
566 
567 static inline void fastopen_queue_tune(struct sock *sk, int backlog)
568 {
569         struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
570         int somaxconn = READ_ONCE(sock_net(sk)->core.sysctl_somaxconn);
571 
572         WRITE_ONCE(queue->fastopenq.max_qlen, min_t(unsigned int, backlog, somaxconn));
573 }
574 
575 static inline void tcp_move_syn(struct tcp_sock *tp,
576                                 struct request_sock *req)
577 {
578         tp->saved_syn = req->saved_syn;
579         req->saved_syn = NULL;
580 }
581 
582 static inline void tcp_saved_syn_free(struct tcp_sock *tp)
583 {
584         kfree(tp->saved_syn);
585         tp->saved_syn = NULL;
586 }
587 
588 static inline u32 tcp_saved_syn_len(const struct saved_syn *saved_syn)
589 {
590         return saved_syn->mac_hdrlen + saved_syn->network_hdrlen +
591                 saved_syn->tcp_hdrlen;
592 }
593 
594 struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk,
595                                                const struct sk_buff *orig_skb,
596                                                const struct sk_buff *ack_skb);
597 
598 static inline u16 tcp_mss_clamp(const struct tcp_sock *tp, u16 mss)
599 {
600         /* We use READ_ONCE() here because socket might not be locked.
601          * This happens for listeners.
602          */
603         u16 user_mss = READ_ONCE(tp->rx_opt.user_mss);
604 
605         return (user_mss && user_mss < mss) ? user_mss : mss;
606 }
607 
608 int tcp_skb_shift(struct sk_buff *to, struct sk_buff *from, int pcount,
609                   int shiftlen);
610 
611 void __tcp_sock_set_cork(struct sock *sk, bool on);
612 void tcp_sock_set_cork(struct sock *sk, bool on);
613 int tcp_sock_set_keepcnt(struct sock *sk, int val);
614 int tcp_sock_set_keepidle_locked(struct sock *sk, int val);
615 int tcp_sock_set_keepidle(struct sock *sk, int val);
616 int tcp_sock_set_keepintvl(struct sock *sk, int val);
617 void __tcp_sock_set_nodelay(struct sock *sk, bool on);
618 void tcp_sock_set_nodelay(struct sock *sk);
619 void tcp_sock_set_quickack(struct sock *sk, int val);
620 int tcp_sock_set_syncnt(struct sock *sk, int val);
621 int tcp_sock_set_user_timeout(struct sock *sk, int val);
622 
623 static inline bool dst_tcp_usec_ts(const struct dst_entry *dst)
624 {
625         return dst_feature(dst, RTAX_FEATURE_TCP_USEC_TS);
626 }
627 
628 #endif  /* _LINUX_TCP_H */
629 

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