net/x25/x25_timer.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      X.25 Packet Layer release 002
   4  *
   5  *      This is ALPHA test software. This code may break your machine,
   6  *      randomly fail to work with new releases, misbehave and/or generally
   7  *      screw up. It might even work.
   8  *
   9  *      This code REQUIRES 2.1.15 or higher
  10  *
  11  *      History
  12  *      X.25 001        Jonathan Naylor Started coding.
  13  *      X.25 002        Jonathan Naylor New timer architecture.
  14  *                                      Centralised disconnection processing.
  15  */
  16
  17 #include <linux/errno.h>
  18 #include <linux/jiffies.h>
  19 #include <linux/timer.h>
  20 #include <net/sock.h>
  21 #include <net/tcp_states.h>
  22 #include <net/x25.h>
  23
  24 static void x25_heartbeat_expiry(struct timer_list *t);
  25 static void x25_timer_expiry(struct timer_list *t);
  26
  27 void x25_init_timers(struct sock *sk)
  28 {
  29         struct x25_sock *x25 = x25_sk(sk);
  30
  31         timer_setup(&x25->timer, x25_timer_expiry, 0);
  32
  33         /* initialized by sock_init_data */
  34         sk->sk_timer.function = x25_heartbeat_expiry;
  35 }
  36
  37 void x25_start_heartbeat(struct sock *sk)
  38 {
  39         mod_timer(&sk->sk_timer, jiffies + 5 * HZ);
  40 }
  41
  42 void x25_stop_heartbeat(struct sock *sk)
  43 {
  44         del_timer(&sk->sk_timer);
  45 }
  46
  47 void x25_start_t2timer(struct sock *sk)
  48 {
  49         struct x25_sock *x25 = x25_sk(sk);
  50
  51         mod_timer(&x25->timer, jiffies + x25->t2);
  52 }
  53
  54 void x25_start_t21timer(struct sock *sk)
  55 {
  56         struct x25_sock *x25 = x25_sk(sk);
  57
  58         mod_timer(&x25->timer, jiffies + x25->t21);
  59 }
  60
  61 void x25_start_t22timer(struct sock *sk)
  62 {
  63         struct x25_sock *x25 = x25_sk(sk);
  64
  65         mod_timer(&x25->timer, jiffies + x25->t22);
  66 }
  67
  68 void x25_start_t23timer(struct sock *sk)
  69 {
  70         struct x25_sock *x25 = x25_sk(sk);
  71
  72         mod_timer(&x25->timer, jiffies + x25->t23);
  73 }
  74
  75 void x25_stop_timer(struct sock *sk)
  76 {
  77         del_timer(&x25_sk(sk)->timer);
  78 }
  79
  80 unsigned long x25_display_timer(struct sock *sk)
  81 {
  82         struct x25_sock *x25 = x25_sk(sk);
  83
  84         if (!timer_pending(&x25->timer))
  85                 return 0;
  86
  87         return x25->timer.expires - jiffies;
  88 }
  89
  90 static void x25_heartbeat_expiry(struct timer_list *t)
  91 {
  92         struct sock *sk = from_timer(sk, t, sk_timer);
  93
  94         bh_lock_sock(sk);
  95         if (sock_owned_by_user(sk)) /* can currently only occur in state 3 */
  96                 goto restart_heartbeat;
  97
  98         switch (x25_sk(sk)->state) {
  99
 100                 case X25_STATE_0:
 101                         /*
 102                          * Magic here: If we listen() and a new link dies
 103                          * before it is accepted() it isn't 'dead' so doesn't
 104                          * get removed.
 105                          */
 106                         if (sock_flag(sk, SOCK_DESTROY) ||
 107                             (sk->sk_state == TCP_LISTEN &&
 108                              sock_flag(sk, SOCK_DEAD))) {
 109                                 bh_unlock_sock(sk);
 110                                 x25_destroy_socket_from_timer(sk);
 111                                 return;
 112                         }
 113                         break;
 114
 115                 case X25_STATE_3:
 116                         /*
 117                          * Check for the state of the receive buffer.
 118                          */
 119                         x25_check_rbuf(sk);
 120                         break;
 121         }
 122 restart_heartbeat:
 123         x25_start_heartbeat(sk);
 124         bh_unlock_sock(sk);
 125 }
 126
 127 /*
 128  *      Timer has expired, it may have been T2, T21, T22, or T23. We can tell
 129  *      by the state machine state.
 130  */
 131 static inline void x25_do_timer_expiry(struct sock * sk)
 132 {
 133         struct x25_sock *x25 = x25_sk(sk);
 134
 135         switch (x25->state) {
 136
 137                 case X25_STATE_3:       /* T2 */
 138                         if (x25->condition & X25_COND_ACK_PENDING) {
 139                                 x25->condition &= ~X25_COND_ACK_PENDING;
 140                                 x25_enquiry_response(sk);
 141                         }
 142                         break;
 143
 144                 case X25_STATE_1:       /* T21 */
 145                 case X25_STATE_4:       /* T22 */
 146                         x25_write_internal(sk, X25_CLEAR_REQUEST);
 147                         x25->state = X25_STATE_2;
 148                         x25_start_t23timer(sk);
 149                         break;
 150
 151                 case X25_STATE_2:       /* T23 */
 152                         x25_disconnect(sk, ETIMEDOUT, 0, 0);
 153                         break;
 154         }
 155 }
 156
 157 static void x25_timer_expiry(struct timer_list *t)
 158 {
 159         struct x25_sock *x25 = from_timer(x25, t, timer);
 160         struct sock *sk = &x25->sk;
 161
 162         bh_lock_sock(sk);
 163         if (sock_owned_by_user(sk)) { /* can currently only occur in state 3 */
 164                 if (x25_sk(sk)->state == X25_STATE_3)
 165                         x25_start_t2timer(sk);
 166         } else
 167                 x25_do_timer_expiry(sk);
 168         bh_unlock_sock(sk);
 169 }