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_stop = false; 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_stop = false; 55 add_timer(&lapb->t2timer); 56 } 57 58 void lapb_stop_t1timer(struct lapb_cb *lapb) 59 { 60 lapb->t1timer_stop = true; 61 del_timer(&lapb->t1timer); 62 } 63 64 void lapb_stop_t2timer(struct lapb_cb *lapb) 65 { 66 lapb->t2timer_stop = true; 67 del_timer(&lapb->t2timer); 68 } 69 70 int lapb_t1timer_running(struct lapb_cb *lapb) 71 { 72 return timer_pending(&lapb->t1timer); 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_stop) /* 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 90 out: 91 spin_unlock_bh(&lapb->lock); 92 } 93 94 static void lapb_t1timer_expiry(struct timer_list *t) 95 { 96 struct lapb_cb *lapb = from_timer(lapb, t, t1timer); 97 98 spin_lock_bh(&lapb->lock); 99 if (timer_pending(&lapb->t1timer)) /* A new timer has been set up */ 100 goto out; 101 if (lapb->t1timer_stop) /* The timer has been stopped */ 102 goto out; 103 104 switch (lapb->state) { 105 106 /* 107 * If we are a DCE, send DM up to N2 times, then switch to 108 * STATE_1 and send SABM(E). 109 */ 110 case LAPB_STATE_0: 111 if (lapb->mode & LAPB_DCE && 112 lapb->n2count != lapb->n2) { 113 lapb->n2count++; 114 lapb_send_control(lapb, LAPB_DM, LAPB_POLLOFF, LAPB_RESPONSE); 115 } else { 116 lapb->state = LAPB_STATE_1; 117 lapb_establish_data_link(lapb); 118 } 119 break; 120 121 /* 122 * Awaiting connection state, send SABM(E), up to N2 times. 123 */ 124 case LAPB_STATE_1: 125 if (lapb->n2count == lapb->n2) { 126 lapb_clear_queues(lapb); 127 lapb->state = LAPB_STATE_0; 128 lapb_disconnect_indication(lapb, LAPB_TIMEDOUT); 129 lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev); 130 goto out; 131 } else { 132 lapb->n2count++; 133 if (lapb->mode & LAPB_EXTENDED) { 134 lapb_dbg(1, "(%p) S1 TX SABME(1)\n", 135 lapb->dev); 136 lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND); 137 } else { 138 lapb_dbg(1, "(%p) S1 TX SABM(1)\n", 139 lapb->dev); 140 lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND); 141 } 142 } 143 break; 144 145 /* 146 * Awaiting disconnection state, send DISC, up to N2 times. 147 */ 148 case LAPB_STATE_2: 149 if (lapb->n2count == lapb->n2) { 150 lapb_clear_queues(lapb); 151 lapb->state = LAPB_STATE_0; 152 lapb_disconnect_confirmation(lapb, LAPB_TIMEDOUT); 153 lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev); 154 goto out; 155 } else { 156 lapb->n2count++; 157 lapb_dbg(1, "(%p) S2 TX DISC(1)\n", lapb->dev); 158 lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND); 159 } 160 break; 161 162 /* 163 * Data transfer state, restransmit I frames, up to N2 times. 164 */ 165 case LAPB_STATE_3: 166 if (lapb->n2count == lapb->n2) { 167 lapb_clear_queues(lapb); 168 lapb->state = LAPB_STATE_0; 169 lapb_stop_t2timer(lapb); 170 lapb_disconnect_indication(lapb, LAPB_TIMEDOUT); 171 lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev); 172 goto out; 173 } else { 174 lapb->n2count++; 175 lapb_requeue_frames(lapb); 176 lapb_kick(lapb); 177 } 178 break; 179 180 /* 181 * Frame reject state, restransmit FRMR frames, up to N2 times. 182 */ 183 case LAPB_STATE_4: 184 if (lapb->n2count == lapb->n2) { 185 lapb_clear_queues(lapb); 186 lapb->state = LAPB_STATE_0; 187 lapb_disconnect_indication(lapb, LAPB_TIMEDOUT); 188 lapb_dbg(0, "(%p) S4 -> S0\n", lapb->dev); 189 goto out; 190 } else { 191 lapb->n2count++; 192 lapb_transmit_frmr(lapb); 193 } 194 break; 195 } 196 197 lapb_start_t1timer(lapb); 198 199 out: 200 spin_unlock_bh(&lapb->lock); 201 } 202