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