xref: /openbmc/linux/net/x25/x25_timer.c (revision 0bea2a65)
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 }
175