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176 lines · 3.9 KiB

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
24static void x25_heartbeat_expiry(struct timer_list *t);
25static void x25_timer_expiry(struct timer_list *t);
26
27void 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
37void x25_start_heartbeat(struct sock *sk)
38{
39 sk_reset_timer(sk, &sk->sk_timer, jiffies + 5 * HZ);
40}
41
42void x25_stop_heartbeat(struct sock *sk)
43{
44 sk_stop_timer(sk, &sk->sk_timer);
45}
46
47void x25_start_t2timer(struct sock *sk)
48{
49 struct x25_sock *x25 = x25_sk(sk);
50
51 sk_reset_timer(sk, &x25->timer, jiffies + x25->t2);
52}
53
54void x25_start_t21timer(struct sock *sk)
55{
56 struct x25_sock *x25 = x25_sk(sk);
57
58 sk_reset_timer(sk, &x25->timer, jiffies + x25->t21);
59}
60
61void x25_start_t22timer(struct sock *sk)
62{
63 struct x25_sock *x25 = x25_sk(sk);
64
65 sk_reset_timer(sk, &x25->timer, jiffies + x25->t22);
66}
67
68void x25_start_t23timer(struct sock *sk)
69{
70 struct x25_sock *x25 = x25_sk(sk);
71
72 sk_reset_timer(sk, &x25->timer, jiffies + x25->t23);
73}
74
75void x25_stop_timer(struct sock *sk)
76{
77 sk_stop_timer(sk, &x25_sk(sk)->timer);
78}
79
80unsigned 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
90static void x25_heartbeat_expiry(struct timer_list *t)
91{
92 struct sock *sk = timer_container_of(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 goto out;
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 }
122restart_heartbeat:
123 /* Do not rearm once __x25_destroy_socket() has unlinked the socket:
124 * it is past its cancel point and owns the teardown from there on.
125 */
126 if (sk_hashed(sk))
127 x25_start_heartbeat(sk);
128 bh_unlock_sock(sk);
129out:
130 sock_put(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 */
137static 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
163static void x25_timer_expiry(struct timer_list *t)
164{
165 struct x25_sock *x25 = timer_container_of(x25, t, timer);
166 struct sock *sk = &x25->sk;
167
168 bh_lock_sock(sk);
169 if (sock_owned_by_user(sk)) { /* can currently only occur in state 3 */
170 if (x25_sk(sk)->state == X25_STATE_3)
171 x25_start_t2timer(sk);
172 } else
173 x25_do_timer_expiry(sk);
174 bh_unlock_sock(sk);
175 sock_put(sk);
176}