net/x25/x25_timer.c

   1 /*
   2  *      X.25 Packet Layer release 002
   3  *
   4  *      This is ALPHA test software. This code may break your machine,
   5  *      randomly fail to work with new releases, misbehave and/or generally
   6  *      screw up. It might even work.
   7  *
   8  *      This code REQUIRES 2.1.15 or higher
   9  *
  10  *      This module:
  11  *              This module is free software; you can redistribute it and/or
  12  *              modify it under the terms of the GNU General Public License
  13  *              as published by the Free Software Foundation; either version
  14  *              2 of the License, or (at your option) any later version.
  15  *
  16  *      History
  17  *      X.25 001        Jonathan Naylor Started coding.
  18  *      X.25 002        Jonathan Naylor New timer architecture.
  19  *                                      Centralised disconnection processing.
  20  */
  21
  22 #include <linux/errno.h>
  23 #include <linux/jiffies.h>
  24 #include <linux/timer.h>
  25 #include <net/sock.h>
  26 #include <net/tcp_states.h>
  27 #include <net/x25.h>
  28
  29 static void x25_heartbeat_expiry(unsigned long);
  30 static void x25_timer_expiry(unsigned long);
  31
  32 void x25_init_timers(struct sock *sk)
  33 {
  34         struct x25_sock *x25 = x25_sk(sk);
  35
  36         setup_timer(&x25->timer, x25_timer_expiry, (unsigned long)sk);
  37
  38         /* initialized by sock_init_data */
  39         sk->sk_timer.data     = (unsigned long)sk;
  40         sk->sk_timer.function = &x25_heartbeat_expiry;
  41 }
  42
  43 void x25_start_heartbeat(struct sock *sk)
  44 {
  45         mod_timer(&sk->sk_timer, jiffies + 5 * HZ);
  46 }
  47
  48 void x25_stop_heartbeat(struct sock *sk)
  49 {
  50         del_timer(&sk->sk_timer);
  51 }
  52
  53 void x25_start_t2timer(struct sock *sk)
  54 {
  55         struct x25_sock *x25 = x25_sk(sk);
  56
  57         mod_timer(&x25->timer, jiffies + x25->t2);
  58 }
  59
  60 void x25_start_t21timer(struct sock *sk)
  61 {
  62         struct x25_sock *x25 = x25_sk(sk);
  63
  64         mod_timer(&x25->timer, jiffies + x25->t21);
  65 }
  66
  67 void x25_start_t22timer(struct sock *sk)
  68 {
  69         struct x25_sock *x25 = x25_sk(sk);
  70
  71         mod_timer(&x25->timer, jiffies + x25->t22);
  72 }
  73
  74 void x25_start_t23timer(struct sock *sk)
  75 {
  76         struct x25_sock *x25 = x25_sk(sk);
  77
  78         mod_timer(&x25->timer, jiffies + x25->t23);
  79 }
  80
  81 void x25_stop_timer(struct sock *sk)
  82 {
  83         del_timer(&x25_sk(sk)->timer);
  84 }
  85
  86 unsigned long x25_display_timer(struct sock *sk)
  87 {
  88         struct x25_sock *x25 = x25_sk(sk);
  89
  90         if (!timer_pending(&x25->timer))
  91                 return 0;
  92
  93         return x25->timer.expires - jiffies;
  94 }
  95
  96 static void x25_heartbeat_expiry(unsigned long param)
  97 {
  98         struct sock *sk = (struct sock *)param;
  99
 100         bh_lock_sock(sk);
 101         if (sock_owned_by_user(sk)) /* can currently only occur in state 3 */
 102                 goto restart_heartbeat;
 103
 104         switch (x25_sk(sk)->state) {
 105
 106                 case X25_STATE_0:
 107                         /*
 108                          * Magic here: If we listen() and a new link dies
 109                          * before it is accepted() it isn't 'dead' so doesn't
 110                          * get removed.
 111                          */
 112                         if (sock_flag(sk, SOCK_DESTROY) ||
 113                             (sk->sk_state == TCP_LISTEN &&
 114                              sock_flag(sk, SOCK_DEAD))) {
 115                                 bh_unlock_sock(sk);
 116                                 x25_destroy_socket_from_timer(sk);
 117                                 return;
 118                         }
 119                         break;
 120
 121                 case X25_STATE_3:
 122                         /*
 123                          * Check for the state of the receive buffer.
 124                          */
 125                         x25_check_rbuf(sk);
 126                         break;
 127         }
 128 restart_heartbeat:
 129         x25_start_heartbeat(sk);
 130         bh_unlock_sock(sk);
 131 }
 132
 133 /*
 134  *      Timer has expired, it may have been T2, T21, T22, or T23. We can tell
 135  *      by the state machine state.
 136  */
 137 static inline void x25_do_timer_expiry(struct sock * sk)
 138 {
 139         struct x25_sock *x25 = x25_sk(sk);
 140
 141         switch (x25->state) {
 142
 143                 case X25_STATE_3:       /* T2 */
 144                         if (x25->condition & X25_COND_ACK_PENDING) {
 145                                 x25->condition &= ~X25_COND_ACK_PENDING;
 146                                 x25_enquiry_response(sk);
 147                         }
 148                         break;
 149
 150                 case X25_STATE_1:       /* T21 */
 151                 case X25_STATE_4:       /* T22 */
 152                         x25_write_internal(sk, X25_CLEAR_REQUEST);
 153                         x25->state = X25_STATE_2;
 154                         x25_start_t23timer(sk);
 155                         break;
 156
 157                 case X25_STATE_2:       /* T23 */
 158                         x25_disconnect(sk, ETIMEDOUT, 0, 0);
 159                         break;
 160         }
 161 }
 162
 163 static void x25_timer_expiry(unsigned long param)
 164 {
 165         struct sock *sk = (struct sock *)param;
 166
 167         bh_lock_sock(sk);
 168         if (sock_owned_by_user(sk)) { /* can currently only occur in state 3 */
 169                 if (x25_sk(sk)->state == X25_STATE_3)
 170                         x25_start_t2timer(sk);
 171         } else
 172                 x25_do_timer_expiry(sk);
 173         bh_unlock_sock(sk);
 174 }