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(struct timer_list *t);
  30 static void x25_timer_expiry(struct timer_list *t);
  31
  32 void x25_init_timers(struct sock *sk)
  33 {
  34         struct x25_sock *x25 = x25_sk(sk);
  35
  36         timer_setup(&x25->timer, x25_timer_expiry, 0);
  37
  38         /* initialized by sock_init_data */
  39         sk->sk_timer.function = x25_heartbeat_expiry;
  40 }
  41
  42 void x25_start_heartbeat(struct sock *sk)
  43 {
  44         mod_timer(&sk->sk_timer, jiffies + 5 * HZ);
  45 }
  46
  47 void x25_stop_heartbeat(struct sock *sk)
  48 {
  49         del_timer(&sk->sk_timer);
  50 }
  51
  52 void x25_start_t2timer(struct sock *sk)
  53 {
  54         struct x25_sock *x25 = x25_sk(sk);
  55
  56         mod_timer(&x25->timer, jiffies + x25->t2);
  57 }
  58
  59 void x25_start_t21timer(struct sock *sk)
  60 {
  61         struct x25_sock *x25 = x25_sk(sk);
  62
  63         mod_timer(&x25->timer, jiffies + x25->t21);
  64 }
  65
  66 void x25_start_t22timer(struct sock *sk)
  67 {
  68         struct x25_sock *x25 = x25_sk(sk);
  69
  70         mod_timer(&x25->timer, jiffies + x25->t22);
  71 }
  72
  73 void x25_start_t23timer(struct sock *sk)
  74 {
  75         struct x25_sock *x25 = x25_sk(sk);
  76
  77         mod_timer(&x25->timer, jiffies + x25->t23);
  78 }
  79
  80 void x25_stop_timer(struct sock *sk)
  81 {
  82         del_timer(&x25_sk(sk)->timer);
  83 }
  84
  85 unsigned long x25_display_timer(struct sock *sk)
  86 {
  87         struct x25_sock *x25 = x25_sk(sk);
  88
  89         if (!timer_pending(&x25->timer))
  90                 return 0;
  91
  92         return x25->timer.expires - jiffies;
  93 }
  94
  95 static void x25_heartbeat_expiry(struct timer_list *t)
  96 {
  97         struct sock *sk = from_timer(sk, t, sk_timer);
  98
  99         bh_lock_sock(sk);
 100         if (sock_owned_by_user(sk)) /* can currently only occur in state 3 */
 101                 goto restart_heartbeat;
 102
 103         switch (x25_sk(sk)->state) {
 104
 105                 case X25_STATE_0:
 106                         /*
 107                          * Magic here: If we listen() and a new link dies
 108                          * before it is accepted() it isn't 'dead' so doesn't
 109                          * get removed.
 110                          */
 111                         if (sock_flag(sk, SOCK_DESTROY) ||
 112                             (sk->sk_state == TCP_LISTEN &&
 113                              sock_flag(sk, SOCK_DEAD))) {
 114                                 bh_unlock_sock(sk);
 115                                 x25_destroy_socket_from_timer(sk);
 116                                 return;
 117                         }
 118                         break;
 119
 120                 case X25_STATE_3:
 121                         /*
 122                          * Check for the state of the receive buffer.
 123                          */
 124                         x25_check_rbuf(sk);
 125                         break;
 126         }
 127 restart_heartbeat:
 128         x25_start_heartbeat(sk);
 129         bh_unlock_sock(sk);
 130 }
 131
 132 /*
 133  *      Timer has expired, it may have been T2, T21, T22, or T23. We can tell
 134  *      by the state machine state.
 135  */
 136 static inline void x25_do_timer_expiry(struct sock * sk)
 137 {
 138         struct x25_sock *x25 = x25_sk(sk);
 139
 140         switch (x25->state) {
 141
 142                 case X25_STATE_3:       /* T2 */
 143                         if (x25->condition & X25_COND_ACK_PENDING) {
 144                                 x25->condition &= ~X25_COND_ACK_PENDING;
 145                                 x25_enquiry_response(sk);
 146                         }
 147                         break;
 148
 149                 case X25_STATE_1:       /* T21 */
 150                 case X25_STATE_4:       /* T22 */
 151                         x25_write_internal(sk, X25_CLEAR_REQUEST);
 152                         x25->state = X25_STATE_2;
 153                         x25_start_t23timer(sk);
 154                         break;
 155
 156                 case X25_STATE_2:       /* T23 */
 157                         x25_disconnect(sk, ETIMEDOUT, 0, 0);
 158                         break;
 159         }
 160 }
 161
 162 static void x25_timer_expiry(struct timer_list *t)
 163 {
 164         struct x25_sock *x25 = from_timer(x25, t, timer);
 165         struct sock *sk = &x25->sk;
 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 }