xref: /kernel/linux/linux-5.10/net/x25/x25_timer.c (revision 8c2ecf20) 
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	mod_timer(&sk->sk_timer, jiffies + 5 * HZ);
40}
41
42void x25_stop_heartbeat(struct sock *sk)
43{
44	del_timer(&sk->sk_timer);
45}
46
47void 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
54void 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
61void 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
68void 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
75void x25_stop_timer(struct sock *sk)
76{
77	del_timer(&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 = 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	}
122restart_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 */
131static 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
157static 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}
170