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         init_timer(&x25->timer);
  37         x25->timer.data     = (unsigned long)sk;
  38         x25->timer.function = &x25_timer_expiry;
  39
  40         /* initialized by sock_init_data */
  41         sk->sk_timer.data     = (unsigned long)sk;
  42         sk->sk_timer.function = &x25_heartbeat_expiry;
  43 }
  44
  45 void x25_start_heartbeat(struct sock *sk)
  46 {
  47         mod_timer(&sk->sk_timer, jiffies + 5 * HZ);
  48 }
  49
  50 void x25_stop_heartbeat(struct sock *sk)
  51 {
  52         del_timer(&sk->sk_timer);
  53 }
  54
  55 void x25_start_t2timer(struct sock *sk)
  56 {
  57         struct x25_sock *x25 = x25_sk(sk);
  58
  59         mod_timer(&x25->timer, jiffies + x25->t2);
  60 }
  61
  62 void x25_start_t21timer(struct sock *sk)
  63 {
  64         struct x25_sock *x25 = x25_sk(sk);
  65
  66         mod_timer(&x25->timer, jiffies + x25->t21);
  67 }
  68
  69 void x25_start_t22timer(struct sock *sk)
  70 {
  71         struct x25_sock *x25 = x25_sk(sk);
  72
  73         mod_timer(&x25->timer, jiffies + x25->t22);
  74 }
  75
  76 void x25_start_t23timer(struct sock *sk)
  77 {
  78         struct x25_sock *x25 = x25_sk(sk);
  79
  80         mod_timer(&x25->timer, jiffies + x25->t23);
  81 }
  82
  83 void x25_stop_timer(struct sock *sk)
  84 {
  85         del_timer(&x25_sk(sk)->timer);
  86 }
  87
  88 unsigned long x25_display_timer(struct sock *sk)
  89 {
  90         struct x25_sock *x25 = x25_sk(sk);
  91
  92         if (!timer_pending(&x25->timer))
  93                 return 0;
  94
  95         return x25->timer.expires - jiffies;
  96 }
  97
  98 static void x25_heartbeat_expiry(unsigned long param)
  99 {
 100         struct sock *sk = (struct sock *)param;
 101
 102         bh_lock_sock(sk);
 103         if (sock_owned_by_user(sk)) /* can currently only occur in state 3 */
 104                 goto restart_heartbeat;
 105
 106         switch (x25_sk(sk)->state) {
 107
 108                 case X25_STATE_0:
 109                         /*
 110                          * Magic here: If we listen() and a new link dies
 111                          * before it is accepted() it isn't 'dead' so doesn't
 112                          * get removed.
 113                          */
 114                         if (sock_flag(sk, SOCK_DESTROY) ||
 115                             (sk->sk_state == TCP_LISTEN &&
 116                              sock_flag(sk, SOCK_DEAD))) {
 117                                 bh_unlock_sock(sk);
 118                                 x25_destroy_socket(sk);
 119                                 return;
 120                         }
 121                         break;
 122
 123                 case X25_STATE_3:
 124                         /*
 125                          * Check for the state of the receive buffer.
 126                          */
 127                         x25_check_rbuf(sk);
 128                         break;
 129         }
 130 restart_heartbeat:
 131         x25_start_heartbeat(sk);
 132         bh_unlock_sock(sk);
 133 }
 134
 135 /*
 136  *      Timer has expired, it may have been T2, T21, T22, or T23. We can tell
 137  *      by the state machine state.
 138  */
 139 static inline void x25_do_timer_expiry(struct sock * sk)
 140 {
 141         struct x25_sock *x25 = x25_sk(sk);
 142
 143         switch (x25->state) {
 144
 145                 case X25_STATE_3:       /* T2 */
 146                         if (x25->condition & X25_COND_ACK_PENDING) {
 147                                 x25->condition &= ~X25_COND_ACK_PENDING;
 148                                 x25_enquiry_response(sk);
 149                         }
 150                         break;
 151
 152                 case X25_STATE_1:       /* T21 */
 153                 case X25_STATE_4:       /* T22 */
 154                         x25_write_internal(sk, X25_CLEAR_REQUEST);
 155                         x25->state = X25_STATE_2;
 156                         x25_start_t23timer(sk);
 157                         break;
 158
 159                 case X25_STATE_2:       /* T23 */
 160                         x25_disconnect(sk, ETIMEDOUT, 0, 0);
 161                         break;
 162         }
 163 }
 164
 165 static void x25_timer_expiry(unsigned long param)
 166 {
 167         struct sock *sk = (struct sock *)param;
 168
 169         bh_lock_sock(sk);
 170         if (sock_owned_by_user(sk)) { /* can currently only occur in state 3 */
 171                 if (x25_sk(sk)->state == X25_STATE_3)
 172                         x25_start_t2timer(sk);
 173         } else
 174                 x25_do_timer_expiry(sk);
 175         bh_unlock_sock(sk);
 176 }