slcan.c revision 87397fe10db0e7ee85041eee5a40052cab66aaff
1/* 2 * slcan.c - serial line CAN interface driver (using tty line discipline) 3 * 4 * This file is derived from linux/drivers/net/slip/slip.c 5 * 6 * slip.c Authors : Laurence Culhane <loz@holmes.demon.co.uk> 7 * Fred N. van Kempen <waltje@uwalt.nl.mugnet.org> 8 * slcan.c Author : Oliver Hartkopp <socketcan@hartkopp.net> 9 * 10 * This program is free software; you can redistribute it and/or modify it 11 * under the terms of the GNU General Public License as published by the 12 * Free Software Foundation; either version 2 of the License, or (at your 13 * option) any later version. 14 * 15 * This program is distributed in the hope that it will be useful, but 16 * WITHOUT ANY WARRANTY; without even the implied warranty of 17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 18 * General Public License for more details. 19 * 20 * You should have received a copy of the GNU General Public License along 21 * with this program; if not, write to the Free Software Foundation, Inc., 22 * 59 Temple Place, Suite 330, Boston, MA 02111-1307. You can also get it 23 * at http://www.gnu.org/licenses/gpl.html 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 26 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 27 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 28 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 29 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 30 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 31 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 35 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 36 * DAMAGE. 37 * 38 */ 39 40#include <linux/module.h> 41#include <linux/moduleparam.h> 42 43#include <linux/uaccess.h> 44#include <linux/bitops.h> 45#include <linux/string.h> 46#include <linux/tty.h> 47#include <linux/errno.h> 48#include <linux/netdevice.h> 49#include <linux/skbuff.h> 50#include <linux/rtnetlink.h> 51#include <linux/if_arp.h> 52#include <linux/if_ether.h> 53#include <linux/sched.h> 54#include <linux/delay.h> 55#include <linux/init.h> 56#include <linux/kernel.h> 57#include <linux/can.h> 58#include <linux/can/skb.h> 59 60static __initconst const char banner[] = 61 KERN_INFO "slcan: serial line CAN interface driver\n"; 62 63MODULE_ALIAS_LDISC(N_SLCAN); 64MODULE_DESCRIPTION("serial line CAN interface"); 65MODULE_LICENSE("GPL"); 66MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>"); 67 68#define SLCAN_MAGIC 0x53CA 69 70static int maxdev = 10; /* MAX number of SLCAN channels; 71 This can be overridden with 72 insmod slcan.ko maxdev=nnn */ 73module_param(maxdev, int, 0); 74MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces"); 75 76/* maximum rx buffer len: extended CAN frame with timestamp */ 77#define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1) 78 79#define SLC_CMD_LEN 1 80#define SLC_SFF_ID_LEN 3 81#define SLC_EFF_ID_LEN 8 82 83struct slcan { 84 int magic; 85 86 /* Various fields. */ 87 struct tty_struct *tty; /* ptr to TTY structure */ 88 struct net_device *dev; /* easy for intr handling */ 89 spinlock_t lock; 90 91 /* These are pointers to the malloc()ed frame buffers. */ 92 unsigned char rbuff[SLC_MTU]; /* receiver buffer */ 93 int rcount; /* received chars counter */ 94 unsigned char xbuff[SLC_MTU]; /* transmitter buffer */ 95 unsigned char *xhead; /* pointer to next XMIT byte */ 96 int xleft; /* bytes left in XMIT queue */ 97 98 unsigned long flags; /* Flag values/ mode etc */ 99#define SLF_INUSE 0 /* Channel in use */ 100#define SLF_ERROR 1 /* Parity, etc. error */ 101}; 102 103static struct net_device **slcan_devs; 104 105 /************************************************************************ 106 * SLCAN ENCAPSULATION FORMAT * 107 ************************************************************************/ 108 109/* 110 * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended 111 * frame format) a data length code (can_dlc) which can be from 0 to 8 112 * and up to <can_dlc> data bytes as payload. 113 * Additionally a CAN frame may become a remote transmission frame if the 114 * RTR-bit is set. This causes another ECU to send a CAN frame with the 115 * given can_id. 116 * 117 * The SLCAN ASCII representation of these different frame types is: 118 * <type> <id> <dlc> <data>* 119 * 120 * Extended frames (29 bit) are defined by capital characters in the type. 121 * RTR frames are defined as 'r' types - normal frames have 't' type: 122 * t => 11 bit data frame 123 * r => 11 bit RTR frame 124 * T => 29 bit data frame 125 * R => 29 bit RTR frame 126 * 127 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64). 128 * The <dlc> is a one byte ASCII number ('0' - '8') 129 * The <data> section has at much ASCII Hex bytes as defined by the <dlc> 130 * 131 * Examples: 132 * 133 * t1230 : can_id 0x123, can_dlc 0, no data 134 * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33 135 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55 136 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request 137 * 138 */ 139 140 /************************************************************************ 141 * STANDARD SLCAN DECAPSULATION * 142 ************************************************************************/ 143 144/* Send one completely decapsulated can_frame to the network layer */ 145static void slc_bump(struct slcan *sl) 146{ 147 struct sk_buff *skb; 148 struct can_frame cf; 149 int i, tmp; 150 u32 tmpid; 151 char *cmd = sl->rbuff; 152 153 cf.can_id = 0; 154 155 switch (*cmd) { 156 case 'r': 157 cf.can_id = CAN_RTR_FLAG; 158 /* fallthrough */ 159 case 't': 160 /* store dlc ASCII value and terminate SFF CAN ID string */ 161 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN]; 162 sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN] = 0; 163 /* point to payload data behind the dlc */ 164 cmd += SLC_CMD_LEN + SLC_SFF_ID_LEN + 1; 165 break; 166 case 'R': 167 cf.can_id = CAN_RTR_FLAG; 168 /* fallthrough */ 169 case 'T': 170 cf.can_id |= CAN_EFF_FLAG; 171 /* store dlc ASCII value and terminate EFF CAN ID string */ 172 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN]; 173 sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN] = 0; 174 /* point to payload data behind the dlc */ 175 cmd += SLC_CMD_LEN + SLC_EFF_ID_LEN + 1; 176 break; 177 default: 178 return; 179 } 180 181 if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid)) 182 return; 183 184 cf.can_id |= tmpid; 185 186 /* get can_dlc from sanitized ASCII value */ 187 if (cf.can_dlc >= '0' && cf.can_dlc < '9') 188 cf.can_dlc -= '0'; 189 else 190 return; 191 192 *(u64 *) (&cf.data) = 0; /* clear payload */ 193 194 /* RTR frames may have a dlc > 0 but they never have any data bytes */ 195 if (!(cf.can_id & CAN_RTR_FLAG)) { 196 for (i = 0; i < cf.can_dlc; i++) { 197 tmp = hex_to_bin(*cmd++); 198 if (tmp < 0) 199 return; 200 cf.data[i] = (tmp << 4); 201 tmp = hex_to_bin(*cmd++); 202 if (tmp < 0) 203 return; 204 cf.data[i] |= tmp; 205 } 206 } 207 208 skb = dev_alloc_skb(sizeof(struct can_frame) + 209 sizeof(struct can_skb_priv)); 210 if (!skb) 211 return; 212 213 skb->dev = sl->dev; 214 skb->protocol = htons(ETH_P_CAN); 215 skb->pkt_type = PACKET_BROADCAST; 216 skb->ip_summed = CHECKSUM_UNNECESSARY; 217 218 can_skb_reserve(skb); 219 can_skb_prv(skb)->ifindex = sl->dev->ifindex; 220 221 memcpy(skb_put(skb, sizeof(struct can_frame)), 222 &cf, sizeof(struct can_frame)); 223 netif_rx_ni(skb); 224 225 sl->dev->stats.rx_packets++; 226 sl->dev->stats.rx_bytes += cf.can_dlc; 227} 228 229/* parse tty input stream */ 230static void slcan_unesc(struct slcan *sl, unsigned char s) 231{ 232 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */ 233 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) && 234 (sl->rcount > 4)) { 235 slc_bump(sl); 236 } 237 sl->rcount = 0; 238 } else { 239 if (!test_bit(SLF_ERROR, &sl->flags)) { 240 if (sl->rcount < SLC_MTU) { 241 sl->rbuff[sl->rcount++] = s; 242 return; 243 } else { 244 sl->dev->stats.rx_over_errors++; 245 set_bit(SLF_ERROR, &sl->flags); 246 } 247 } 248 } 249} 250 251 /************************************************************************ 252 * STANDARD SLCAN ENCAPSULATION * 253 ************************************************************************/ 254 255/* Encapsulate one can_frame and stuff into a TTY queue. */ 256static void slc_encaps(struct slcan *sl, struct can_frame *cf) 257{ 258 int actual, i; 259 unsigned char *pos; 260 unsigned char *endpos; 261 canid_t id = cf->can_id; 262 263 pos = sl->xbuff; 264 265 if (cf->can_id & CAN_RTR_FLAG) 266 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */ 267 else 268 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */ 269 270 /* determine number of chars for the CAN-identifier */ 271 if (cf->can_id & CAN_EFF_FLAG) { 272 id &= CAN_EFF_MASK; 273 endpos = pos + SLC_EFF_ID_LEN; 274 } else { 275 *pos |= 0x20; /* convert R/T to lower case for SFF */ 276 id &= CAN_SFF_MASK; 277 endpos = pos + SLC_SFF_ID_LEN; 278 } 279 280 /* build 3 (SFF) or 8 (EFF) digit CAN identifier */ 281 pos++; 282 while (endpos >= pos) { 283 *endpos-- = hex_asc_upper[id & 0xf]; 284 id >>= 4; 285 } 286 287 pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN; 288 289 *pos++ = cf->can_dlc + '0'; 290 291 /* RTR frames may have a dlc > 0 but they never have any data bytes */ 292 if (!(cf->can_id & CAN_RTR_FLAG)) { 293 for (i = 0; i < cf->can_dlc; i++) 294 pos = hex_byte_pack_upper(pos, cf->data[i]); 295 } 296 297 *pos++ = '\r'; 298 299 /* Order of next two lines is *very* important. 300 * When we are sending a little amount of data, 301 * the transfer may be completed inside the ops->write() 302 * routine, because it's running with interrupts enabled. 303 * In this case we *never* got WRITE_WAKEUP event, 304 * if we did not request it before write operation. 305 * 14 Oct 1994 Dmitry Gorodchanin. 306 */ 307 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); 308 actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff); 309 sl->xleft = (pos - sl->xbuff) - actual; 310 sl->xhead = sl->xbuff + actual; 311 sl->dev->stats.tx_bytes += cf->can_dlc; 312} 313 314/* 315 * Called by the driver when there's room for more data. If we have 316 * more packets to send, we send them here. 317 */ 318static void slcan_write_wakeup(struct tty_struct *tty) 319{ 320 int actual; 321 struct slcan *sl = (struct slcan *) tty->disc_data; 322 323 /* First make sure we're connected. */ 324 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) 325 return; 326 327 spin_lock(&sl->lock); 328 if (sl->xleft <= 0) { 329 /* Now serial buffer is almost free & we can start 330 * transmission of another packet */ 331 sl->dev->stats.tx_packets++; 332 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); 333 spin_unlock(&sl->lock); 334 netif_wake_queue(sl->dev); 335 return; 336 } 337 338 actual = tty->ops->write(tty, sl->xhead, sl->xleft); 339 sl->xleft -= actual; 340 sl->xhead += actual; 341 spin_unlock(&sl->lock); 342} 343 344/* Send a can_frame to a TTY queue. */ 345static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev) 346{ 347 struct slcan *sl = netdev_priv(dev); 348 349 if (skb->len != sizeof(struct can_frame)) 350 goto out; 351 352 spin_lock(&sl->lock); 353 if (!netif_running(dev)) { 354 spin_unlock(&sl->lock); 355 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name); 356 goto out; 357 } 358 if (sl->tty == NULL) { 359 spin_unlock(&sl->lock); 360 goto out; 361 } 362 363 netif_stop_queue(sl->dev); 364 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */ 365 spin_unlock(&sl->lock); 366 367out: 368 kfree_skb(skb); 369 return NETDEV_TX_OK; 370} 371 372 373/****************************************** 374 * Routines looking at netdevice side. 375 ******************************************/ 376 377/* Netdevice UP -> DOWN routine */ 378static int slc_close(struct net_device *dev) 379{ 380 struct slcan *sl = netdev_priv(dev); 381 382 spin_lock_bh(&sl->lock); 383 if (sl->tty) { 384 /* TTY discipline is running. */ 385 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); 386 } 387 netif_stop_queue(dev); 388 sl->rcount = 0; 389 sl->xleft = 0; 390 spin_unlock_bh(&sl->lock); 391 392 return 0; 393} 394 395/* Netdevice DOWN -> UP routine */ 396static int slc_open(struct net_device *dev) 397{ 398 struct slcan *sl = netdev_priv(dev); 399 400 if (sl->tty == NULL) 401 return -ENODEV; 402 403 sl->flags &= (1 << SLF_INUSE); 404 netif_start_queue(dev); 405 return 0; 406} 407 408/* Hook the destructor so we can free slcan devs at the right point in time */ 409static void slc_free_netdev(struct net_device *dev) 410{ 411 int i = dev->base_addr; 412 free_netdev(dev); 413 slcan_devs[i] = NULL; 414} 415 416static const struct net_device_ops slc_netdev_ops = { 417 .ndo_open = slc_open, 418 .ndo_stop = slc_close, 419 .ndo_start_xmit = slc_xmit, 420}; 421 422static void slc_setup(struct net_device *dev) 423{ 424 dev->netdev_ops = &slc_netdev_ops; 425 dev->destructor = slc_free_netdev; 426 427 dev->hard_header_len = 0; 428 dev->addr_len = 0; 429 dev->tx_queue_len = 10; 430 431 dev->mtu = sizeof(struct can_frame); 432 dev->type = ARPHRD_CAN; 433 434 /* New-style flags. */ 435 dev->flags = IFF_NOARP; 436 dev->features = NETIF_F_HW_CSUM; 437} 438 439/****************************************** 440 Routines looking at TTY side. 441 ******************************************/ 442 443/* 444 * Handle the 'receiver data ready' interrupt. 445 * This function is called by the 'tty_io' module in the kernel when 446 * a block of SLCAN data has been received, which can now be decapsulated 447 * and sent on to some IP layer for further processing. This will not 448 * be re-entered while running but other ldisc functions may be called 449 * in parallel 450 */ 451 452static void slcan_receive_buf(struct tty_struct *tty, 453 const unsigned char *cp, char *fp, int count) 454{ 455 struct slcan *sl = (struct slcan *) tty->disc_data; 456 457 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) 458 return; 459 460 /* Read the characters out of the buffer */ 461 while (count--) { 462 if (fp && *fp++) { 463 if (!test_and_set_bit(SLF_ERROR, &sl->flags)) 464 sl->dev->stats.rx_errors++; 465 cp++; 466 continue; 467 } 468 slcan_unesc(sl, *cp++); 469 } 470} 471 472/************************************ 473 * slcan_open helper routines. 474 ************************************/ 475 476/* Collect hanged up channels */ 477static void slc_sync(void) 478{ 479 int i; 480 struct net_device *dev; 481 struct slcan *sl; 482 483 for (i = 0; i < maxdev; i++) { 484 dev = slcan_devs[i]; 485 if (dev == NULL) 486 break; 487 488 sl = netdev_priv(dev); 489 if (sl->tty) 490 continue; 491 if (dev->flags & IFF_UP) 492 dev_close(dev); 493 } 494} 495 496/* Find a free SLCAN channel, and link in this `tty' line. */ 497static struct slcan *slc_alloc(dev_t line) 498{ 499 int i; 500 char name[IFNAMSIZ]; 501 struct net_device *dev = NULL; 502 struct slcan *sl; 503 504 for (i = 0; i < maxdev; i++) { 505 dev = slcan_devs[i]; 506 if (dev == NULL) 507 break; 508 509 } 510 511 /* Sorry, too many, all slots in use */ 512 if (i >= maxdev) 513 return NULL; 514 515 sprintf(name, "slcan%d", i); 516 dev = alloc_netdev(sizeof(*sl), name, slc_setup); 517 if (!dev) 518 return NULL; 519 520 dev->base_addr = i; 521 sl = netdev_priv(dev); 522 523 /* Initialize channel control data */ 524 sl->magic = SLCAN_MAGIC; 525 sl->dev = dev; 526 spin_lock_init(&sl->lock); 527 slcan_devs[i] = dev; 528 529 return sl; 530} 531 532/* 533 * Open the high-level part of the SLCAN channel. 534 * This function is called by the TTY module when the 535 * SLCAN line discipline is called for. Because we are 536 * sure the tty line exists, we only have to link it to 537 * a free SLCAN channel... 538 * 539 * Called in process context serialized from other ldisc calls. 540 */ 541 542static int slcan_open(struct tty_struct *tty) 543{ 544 struct slcan *sl; 545 int err; 546 547 if (!capable(CAP_NET_ADMIN)) 548 return -EPERM; 549 550 if (tty->ops->write == NULL) 551 return -EOPNOTSUPP; 552 553 /* RTnetlink lock is misused here to serialize concurrent 554 opens of slcan channels. There are better ways, but it is 555 the simplest one. 556 */ 557 rtnl_lock(); 558 559 /* Collect hanged up channels. */ 560 slc_sync(); 561 562 sl = tty->disc_data; 563 564 err = -EEXIST; 565 /* First make sure we're not already connected. */ 566 if (sl && sl->magic == SLCAN_MAGIC) 567 goto err_exit; 568 569 /* OK. Find a free SLCAN channel to use. */ 570 err = -ENFILE; 571 sl = slc_alloc(tty_devnum(tty)); 572 if (sl == NULL) 573 goto err_exit; 574 575 sl->tty = tty; 576 tty->disc_data = sl; 577 578 if (!test_bit(SLF_INUSE, &sl->flags)) { 579 /* Perform the low-level SLCAN initialization. */ 580 sl->rcount = 0; 581 sl->xleft = 0; 582 583 set_bit(SLF_INUSE, &sl->flags); 584 585 err = register_netdevice(sl->dev); 586 if (err) 587 goto err_free_chan; 588 } 589 590 /* Done. We have linked the TTY line to a channel. */ 591 rtnl_unlock(); 592 tty->receive_room = 65536; /* We don't flow control */ 593 594 /* TTY layer expects 0 on success */ 595 return 0; 596 597err_free_chan: 598 sl->tty = NULL; 599 tty->disc_data = NULL; 600 clear_bit(SLF_INUSE, &sl->flags); 601 602err_exit: 603 rtnl_unlock(); 604 605 /* Count references from TTY module */ 606 return err; 607} 608 609/* 610 * Close down a SLCAN channel. 611 * This means flushing out any pending queues, and then returning. This 612 * call is serialized against other ldisc functions. 613 * 614 * We also use this method for a hangup event. 615 */ 616 617static void slcan_close(struct tty_struct *tty) 618{ 619 struct slcan *sl = (struct slcan *) tty->disc_data; 620 621 /* First make sure we're connected. */ 622 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty) 623 return; 624 625 tty->disc_data = NULL; 626 sl->tty = NULL; 627 628 /* Flush network side */ 629 unregister_netdev(sl->dev); 630 /* This will complete via sl_free_netdev */ 631} 632 633static int slcan_hangup(struct tty_struct *tty) 634{ 635 slcan_close(tty); 636 return 0; 637} 638 639/* Perform I/O control on an active SLCAN channel. */ 640static int slcan_ioctl(struct tty_struct *tty, struct file *file, 641 unsigned int cmd, unsigned long arg) 642{ 643 struct slcan *sl = (struct slcan *) tty->disc_data; 644 unsigned int tmp; 645 646 /* First make sure we're connected. */ 647 if (!sl || sl->magic != SLCAN_MAGIC) 648 return -EINVAL; 649 650 switch (cmd) { 651 case SIOCGIFNAME: 652 tmp = strlen(sl->dev->name) + 1; 653 if (copy_to_user((void __user *)arg, sl->dev->name, tmp)) 654 return -EFAULT; 655 return 0; 656 657 case SIOCSIFHWADDR: 658 return -EINVAL; 659 660 default: 661 return tty_mode_ioctl(tty, file, cmd, arg); 662 } 663} 664 665static struct tty_ldisc_ops slc_ldisc = { 666 .owner = THIS_MODULE, 667 .magic = TTY_LDISC_MAGIC, 668 .name = "slcan", 669 .open = slcan_open, 670 .close = slcan_close, 671 .hangup = slcan_hangup, 672 .ioctl = slcan_ioctl, 673 .receive_buf = slcan_receive_buf, 674 .write_wakeup = slcan_write_wakeup, 675}; 676 677static int __init slcan_init(void) 678{ 679 int status; 680 681 if (maxdev < 4) 682 maxdev = 4; /* Sanity */ 683 684 printk(banner); 685 printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev); 686 687 slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL); 688 if (!slcan_devs) 689 return -ENOMEM; 690 691 /* Fill in our line protocol discipline, and register it */ 692 status = tty_register_ldisc(N_SLCAN, &slc_ldisc); 693 if (status) { 694 printk(KERN_ERR "slcan: can't register line discipline\n"); 695 kfree(slcan_devs); 696 } 697 return status; 698} 699 700static void __exit slcan_exit(void) 701{ 702 int i; 703 struct net_device *dev; 704 struct slcan *sl; 705 unsigned long timeout = jiffies + HZ; 706 int busy = 0; 707 708 if (slcan_devs == NULL) 709 return; 710 711 /* First of all: check for active disciplines and hangup them. 712 */ 713 do { 714 if (busy) 715 msleep_interruptible(100); 716 717 busy = 0; 718 for (i = 0; i < maxdev; i++) { 719 dev = slcan_devs[i]; 720 if (!dev) 721 continue; 722 sl = netdev_priv(dev); 723 spin_lock_bh(&sl->lock); 724 if (sl->tty) { 725 busy++; 726 tty_hangup(sl->tty); 727 } 728 spin_unlock_bh(&sl->lock); 729 } 730 } while (busy && time_before(jiffies, timeout)); 731 732 /* FIXME: hangup is async so we should wait when doing this second 733 phase */ 734 735 for (i = 0; i < maxdev; i++) { 736 dev = slcan_devs[i]; 737 if (!dev) 738 continue; 739 slcan_devs[i] = NULL; 740 741 sl = netdev_priv(dev); 742 if (sl->tty) { 743 printk(KERN_ERR "%s: tty discipline still running\n", 744 dev->name); 745 /* Intentionally leak the control block. */ 746 dev->destructor = NULL; 747 } 748 749 unregister_netdev(dev); 750 } 751 752 kfree(slcan_devs); 753 slcan_devs = NULL; 754 755 i = tty_unregister_ldisc(N_SLCAN); 756 if (i) 757 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i); 758} 759 760module_init(slcan_init); 761module_exit(slcan_exit); 762