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(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(timer: &lapb->t1timer); |
45 | } |
46 | |
47 | void lapb_start_t2timer(struct lapb_cb *lapb) |
48 | { |
49 | del_timer(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(timer: &lapb->t2timer); |
56 | } |
57 | |
58 | void lapb_stop_t1timer(struct lapb_cb *lapb) |
59 | { |
60 | lapb->t1timer_running = false; |
61 | del_timer(timer: &lapb->t1timer); |
62 | } |
63 | |
64 | void lapb_stop_t2timer(struct lapb_cb *lapb) |
65 | { |
66 | lapb->t2timer_running = false; |
67 | del_timer(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(lock: &lapb->lock); |
80 | if (timer_pending(timer: &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(lock: &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(lock: &lapb->lock); |
100 | if (timer_pending(timer: &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(lock: &lapb->lock); |
206 | } |
207 | |