1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * LAPB release 002
4 *
5 * This code REQUIRES 2.1.15 or higher/ NET3.038
6 *
7 * History
8 * LAPB 001 Jonathan Naylor Started Coding
9 * LAPB 002 Jonathan Naylor New timer architecture.
10 */
11
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14 #include <linux/errno.h>
15 #include <linux/types.h>
16 #include <linux/socket.h>
17 #include <linux/in.h>
18 #include <linux/kernel.h>
19 #include <linux/jiffies.h>
20 #include <linux/timer.h>
21 #include <linux/string.h>
22 #include <linux/sockios.h>
23 #include <linux/net.h>
24 #include <linux/inet.h>
25 #include <linux/skbuff.h>
26 #include <net/sock.h>
27 #include <linux/uaccess.h>
28 #include <linux/fcntl.h>
29 #include <linux/mm.h>
30 #include <linux/interrupt.h>
31 #include <net/lapb.h>
32
33 static void lapb_t1timer_expiry(struct timer_list *);
34 static void lapb_t2timer_expiry(struct timer_list *);
35
36 void lapb_start_t1timer(struct lapb_cb *lapb)
37 {
38 del_timer(&lapb->t1timer);
39
40 lapb->t1timer.function = lapb_t1timer_expiry;
41 lapb->t1timer.expires = jiffies + lapb->t1;
42
43 lapb->t1timer_running = true;
44 add_timer(&lapb->t1timer);
45 }
46
47 void lapb_start_t2timer(struct lapb_cb *lapb)
48 {
49 del_timer(&lapb->t2timer);
50
51 lapb->t2timer.function = lapb_t2timer_expiry;
52 lapb->t2timer.expires = jiffies + lapb->t2;
53
54 lapb->t2timer_running = true;
55 add_timer(&lapb->t2timer);
56 }
57
58 void lapb_stop_t1timer(struct lapb_cb *lapb)
59 {
60 lapb->t1timer_running = false;
61 del_timer(&lapb->t1timer);
62 }
63
64 void lapb_stop_t2timer(struct lapb_cb *lapb)
65 {
66 lapb->t2timer_running = false;
67 del_timer(&lapb->t2timer);
68 }
69
70 int lapb_t1timer_running(struct lapb_cb *lapb)
71 {
72 return lapb->t1timer_running;
73 }
74
75 static void lapb_t2timer_expiry(struct timer_list *t)
76 {
77 struct lapb_cb *lapb = from_timer(lapb, t, t2timer);
78
79 spin_lock_bh(&lapb->lock);
80 if (timer_pending(&lapb->t2timer)) /* A new timer has been set up */
81 goto out;
82 if (!lapb->t2timer_running) /* The timer has been stopped */
83 goto out;
84
85 if (lapb->condition & LAPB_ACK_PENDING_CONDITION) {
86 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
87 lapb_timeout_response(lapb);
88 }
89 lapb->t2timer_running = false;
90
91 out:
92 spin_unlock_bh(&lapb->lock);
93 }
94
95 static void lapb_t1timer_expiry(struct timer_list *t)
96 {
97 struct lapb_cb *lapb = from_timer(lapb, t, t1timer);
98
99 spin_lock_bh(&lapb->lock);
100 if (timer_pending(&lapb->t1timer)) /* A new timer has been set up */
101 goto out;
102 if (!lapb->t1timer_running) /* The timer has been stopped */
103 goto out;
104
105 switch (lapb->state) {
106
107 /*
108 * If we are a DCE, send DM up to N2 times, then switch to
109 * STATE_1 and send SABM(E).
110 */
111 case LAPB_STATE_0:
112 if (lapb->mode & LAPB_DCE &&
113 lapb->n2count != lapb->n2) {
114 lapb->n2count++;
115 lapb_send_control(lapb, LAPB_DM, LAPB_POLLOFF, LAPB_RESPONSE);
116 } else {
117 lapb->state = LAPB_STATE_1;
118 lapb_establish_data_link(lapb);
119 }
120 break;
121
122 /*
123 * Awaiting connection state, send SABM(E), up to N2 times.
124 */
125 case LAPB_STATE_1:
126 if (lapb->n2count == lapb->n2) {
127 lapb_clear_queues(lapb);
128 lapb->state = LAPB_STATE_0;
129 lapb_disconnect_indication(lapb, LAPB_TIMEDOUT);
130 lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev);
131 lapb->t1timer_running = false;
132 goto out;
133 } else {
134 lapb->n2count++;
135 if (lapb->mode & LAPB_EXTENDED) {
136 lapb_dbg(1, "(%p) S1 TX SABME(1)\n",
137 lapb->dev);
138 lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
139 } else {
140 lapb_dbg(1, "(%p) S1 TX SABM(1)\n",
141 lapb->dev);
142 lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
143 }
144 }
145 break;
146
147 /*
148 * Awaiting disconnection state, send DISC, up to N2 times.
149 */
150 case LAPB_STATE_2:
151 if (lapb->n2count == lapb->n2) {
152 lapb_clear_queues(lapb);
153 lapb->state = LAPB_STATE_0;
154 lapb_disconnect_confirmation(lapb, LAPB_TIMEDOUT);
155 lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev);
156 lapb->t1timer_running = false;
157 goto out;
158 } else {
159 lapb->n2count++;
160 lapb_dbg(1, "(%p) S2 TX DISC(1)\n", lapb->dev);
161 lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
162 }
163 break;
164
165 /*
166 * Data transfer state, restransmit I frames, up to N2 times.
167 */
168 case LAPB_STATE_3:
169 if (lapb->n2count == lapb->n2) {
170 lapb_clear_queues(lapb);
171 lapb->state = LAPB_STATE_0;
172 lapb_stop_t2timer(lapb);
173 lapb_disconnect_indication(lapb, LAPB_TIMEDOUT);
174 lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev);
175 lapb->t1timer_running = false;
176 goto out;
177 } else {
178 lapb->n2count++;
179 lapb_requeue_frames(lapb);
180 lapb_kick(lapb);
181 }
182 break;
183
184 /*
185 * Frame reject state, restransmit FRMR frames, up to N2 times.
186 */
187 case LAPB_STATE_4:
188 if (lapb->n2count == lapb->n2) {
189 lapb_clear_queues(lapb);
190 lapb->state = LAPB_STATE_0;
191 lapb_disconnect_indication(lapb, LAPB_TIMEDOUT);
192 lapb_dbg(0, "(%p) S4 -> S0\n", lapb->dev);
193 lapb->t1timer_running = false;
194 goto out;
195 } else {
196 lapb->n2count++;
197 lapb_transmit_frmr(lapb);
198 }
199 break;
200 }
201
202 lapb_start_t1timer(lapb);
203
204 out:
205 spin_unlock_bh(&lapb->lock);
206 }
207
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