net/x25/x25_timer.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  X.25 Packet Layer release 002
0004  *
0005  *  This is ALPHA test software. This code may break your machine,
0006  *  randomly fail to work with new releases, misbehave and/or generally
0007  *  screw up. It might even work.
0008  *
0009  *  This code REQUIRES 2.1.15 or higher
0010  *
0011  *  History
0012  *  X.25 001    Jonathan Naylor Started coding.
0013  *  X.25 002    Jonathan Naylor New timer architecture.
0014  *                  Centralised disconnection processing.
0015  */
0016
0017 #include <linux/errno.h>
0018 #include <linux/jiffies.h>
0019 #include <linux/timer.h>
0020 #include <net/sock.h>
0021 #include <net/tcp_states.h>
0022 #include <net/x25.h>
0023
0024 static void x25_heartbeat_expiry(struct timer_list *t);
0025 static void x25_timer_expiry(struct timer_list *t);
0026
0027 void x25_init_timers(struct sock *sk)
0028 {
0029     struct x25_sock *x25 = x25_sk(sk);
0030
0031     timer_setup(&x25->timer, x25_timer_expiry, 0);
0032
0033     /* initialized by sock_init_data */
0034     sk->sk_timer.function = x25_heartbeat_expiry;
0035 }
0036
0037 void x25_start_heartbeat(struct sock *sk)
0038 {
0039     mod_timer(&sk->sk_timer, jiffies + 5 * HZ);
0040 }
0041
0042 void x25_stop_heartbeat(struct sock *sk)
0043 {
0044     del_timer(&sk->sk_timer);
0045 }
0046
0047 void x25_start_t2timer(struct sock *sk)
0048 {
0049     struct x25_sock *x25 = x25_sk(sk);
0050
0051     mod_timer(&x25->timer, jiffies + x25->t2);
0052 }
0053
0054 void x25_start_t21timer(struct sock *sk)
0055 {
0056     struct x25_sock *x25 = x25_sk(sk);
0057
0058     mod_timer(&x25->timer, jiffies + x25->t21);
0059 }
0060
0061 void x25_start_t22timer(struct sock *sk)
0062 {
0063     struct x25_sock *x25 = x25_sk(sk);
0064
0065     mod_timer(&x25->timer, jiffies + x25->t22);
0066 }
0067
0068 void x25_start_t23timer(struct sock *sk)
0069 {
0070     struct x25_sock *x25 = x25_sk(sk);
0071
0072     mod_timer(&x25->timer, jiffies + x25->t23);
0073 }
0074
0075 void x25_stop_timer(struct sock *sk)
0076 {
0077     del_timer(&x25_sk(sk)->timer);
0078 }
0079
0080 unsigned long x25_display_timer(struct sock *sk)
0081 {
0082     struct x25_sock *x25 = x25_sk(sk);
0083
0084     if (!timer_pending(&x25->timer))
0085         return 0;
0086
0087     return x25->timer.expires - jiffies;
0088 }
0089
0090 static void x25_heartbeat_expiry(struct timer_list *t)
0091 {
0092     struct sock *sk = from_timer(sk, t, sk_timer);
0093
0094     bh_lock_sock(sk);
0095     if (sock_owned_by_user(sk)) /* can currently only occur in state 3 */
0096         goto restart_heartbeat;
0097
0098     switch (x25_sk(sk)->state) {
0099
0100         case X25_STATE_0:
0101             /*
0102              * Magic here: If we listen() and a new link dies
0103              * before it is accepted() it isn't 'dead' so doesn't
0104              * get removed.
0105              */
0106             if (sock_flag(sk, SOCK_DESTROY) ||
0107                 (sk->sk_state == TCP_LISTEN &&
0108                  sock_flag(sk, SOCK_DEAD))) {
0109                 bh_unlock_sock(sk);
0110                 x25_destroy_socket_from_timer(sk);
0111                 return;
0112             }
0113             break;
0114
0115         case X25_STATE_3:
0116             /*
0117              * Check for the state of the receive buffer.
0118              */
0119             x25_check_rbuf(sk);
0120             break;
0121     }
0122 restart_heartbeat:
0123     x25_start_heartbeat(sk);
0124     bh_unlock_sock(sk);
0125 }
0126
0127 /*
0128  *  Timer has expired, it may have been T2, T21, T22, or T23. We can tell
0129  *  by the state machine state.
0130  */
0131 static inline void x25_do_timer_expiry(struct sock * sk)
0132 {
0133     struct x25_sock *x25 = x25_sk(sk);
0134
0135     switch (x25->state) {
0136
0137         case X25_STATE_3:   /* T2 */
0138             if (x25->condition & X25_COND_ACK_PENDING) {
0139                 x25->condition &= ~X25_COND_ACK_PENDING;
0140                 x25_enquiry_response(sk);
0141             }
0142             break;
0143
0144         case X25_STATE_1:   /* T21 */
0145         case X25_STATE_4:   /* T22 */
0146             x25_write_internal(sk, X25_CLEAR_REQUEST);
0147             x25->state = X25_STATE_2;
0148             x25_start_t23timer(sk);
0149             break;
0150
0151         case X25_STATE_2:   /* T23 */
0152             x25_disconnect(sk, ETIMEDOUT, 0, 0);
0153             break;
0154     }
0155 }
0156
0157 static void x25_timer_expiry(struct timer_list *t)
0158 {
0159     struct x25_sock *x25 = from_timer(x25, t, timer);
0160     struct sock *sk = &x25->sk;
0161
0162     bh_lock_sock(sk);
0163     if (sock_owned_by_user(sk)) { /* can currently only occur in state 3 */
0164         if (x25_sk(sk)->state == X25_STATE_3)
0165             x25_start_t2timer(sk);
0166     } else
0167         x25_do_timer_expiry(sk);
0168     bh_unlock_sock(sk);
0169 }