11553 Want pluggable TCP congestion control algorithms
Portions contributed by: Cody Peter Mello <cody.mello@joyent.com>
Reviewed by: Dan McDonald <danmcd@joyent.com>
Reviewed by: Robert Mustacchi <robert.mustacchi@joyent.com>

*** 19,29 ****
   * CDDL HEADER END
   */
  
  /*
   * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright (c) 2014, 2016 by Delphix. All rights reserved.
   * Copyright 2019 Joyent, Inc.
   */
  
  /* This file contains all TCP output processing functions. */
  
--- 19,29 ----
   * CDDL HEADER END
   */
  
  /*
   * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright (c) 2014, 2017 by Delphix. All rights reserved.
   * Copyright 2019 Joyent, Inc.
   */
  
  /* This file contains all TCP output processing functions. */
  
*** 79,88 ****
--- 79,100 ----
   * speedup is observed for values larger than sixteen.  Zero will
   * disable the optimisation.
   */
  static int tcp_tx_pull_len = 16;
  
+ static void
+ cc_after_idle(tcp_t *tcp)
+ {
+         uint32_t old_cwnd = tcp->tcp_cwnd;
+ 
+         if (CC_ALGO(tcp)->after_idle != NULL)
+                 CC_ALGO(tcp)->after_idle(&tcp->tcp_ccv);
+ 
+         DTRACE_PROBE3(cwnd__cc__after__idle, tcp_t *, tcp, uint32_t, old_cwnd,
+             uint32_t, tcp->tcp_cwnd);
+ }
+ 
  int
  tcp_wput(queue_t *q, mblk_t *mp)
  {
          conn_t  *connp = Q_TO_CONN(q);
          tcp_t   *tcp;
*** 217,227 ****
          int32_t         mss;
          int32_t         num_sack_blk = 0;
          int32_t         total_hdr_len;
          int32_t         tcp_hdr_len;
          int             rc;
-         tcp_stack_t     *tcps = tcp->tcp_tcps;
          conn_t          *connp = tcp->tcp_connp;
          clock_t         now = LBOLT_FASTPATH;
  
          tcpstate = tcp->tcp_state;
          if (mp == NULL) {
--- 229,238 ----
*** 372,382 ****
                  tcp_hdr_len = connp->conn_ht_ulp_len;
          }
  
          if ((tcp->tcp_suna == snxt) && !tcp->tcp_localnet &&
              (TICK_TO_MSEC(now - tcp->tcp_last_recv_time) >= tcp->tcp_rto)) {
!                 TCP_SET_INIT_CWND(tcp, mss, tcps->tcps_slow_start_after_idle);
          }
          if (tcpstate == TCPS_SYN_RCVD) {
                  /*
                   * The three-way connection establishment handshake is not
                   * complete yet. We want to queue the data for transmission
--- 383,393 ----
                  tcp_hdr_len = connp->conn_ht_ulp_len;
          }
  
          if ((tcp->tcp_suna == snxt) && !tcp->tcp_localnet &&
              (TICK_TO_MSEC(now - tcp->tcp_last_recv_time) >= tcp->tcp_rto)) {
!                 cc_after_idle(tcp);
          }
          if (tcpstate == TCPS_SYN_RCVD) {
                  /*
                   * The three-way connection establishment handshake is not
                   * complete yet. We want to queue the data for transmission
*** 1193,1203 ****
           * "Congestion avoidance and control".
           */
          now = LBOLT_FASTPATH;
          if ((tcp->tcp_suna == snxt) && !tcp->tcp_localnet &&
              (TICK_TO_MSEC(now - tcp->tcp_last_recv_time) >= tcp->tcp_rto)) {
!                 TCP_SET_INIT_CWND(tcp, mss, tcps->tcps_slow_start_after_idle);
          }
  
          usable = tcp->tcp_swnd;         /* tcp window size */
          if (usable > tcp->tcp_cwnd)
                  usable = tcp->tcp_cwnd; /* congestion window smaller */
--- 1204,1214 ----
           * "Congestion avoidance and control".
           */
          now = LBOLT_FASTPATH;
          if ((tcp->tcp_suna == snxt) && !tcp->tcp_localnet &&
              (TICK_TO_MSEC(now - tcp->tcp_last_recv_time) >= tcp->tcp_rto)) {
!                 cc_after_idle(tcp);
          }
  
          usable = tcp->tcp_swnd;         /* tcp window size */
          if (usable > tcp->tcp_cwnd)
                  usable = tcp->tcp_cwnd; /* congestion window smaller */