slcan.c revision c971fa2ae42e73e9ccc2f5e93f268c8742da4c5d
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, see http://www.gnu.org/licenses/gpl.html 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 26 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 27 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 29 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 33 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 34 * DAMAGE. 35 * 36 */ 37 38#include <linux/module.h> 39#include <linux/moduleparam.h> 40 41#include <linux/uaccess.h> 42#include <linux/bitops.h> 43#include <linux/string.h> 44#include <linux/tty.h> 45#include <linux/errno.h> 46#include <linux/netdevice.h> 47#include <linux/skbuff.h> 48#include <linux/rtnetlink.h> 49#include <linux/if_arp.h> 50#include <linux/if_ether.h> 51#include <linux/sched.h> 52#include <linux/delay.h> 53#include <linux/init.h> 54#include <linux/kernel.h> 55#include <linux/can.h> 56#include <linux/can/skb.h> 57 58static __initconst const char banner[] = 59 KERN_INFO "slcan: serial line CAN interface driver\n"; 60 61MODULE_ALIAS_LDISC(N_SLCAN); 62MODULE_DESCRIPTION("serial line CAN interface"); 63MODULE_LICENSE("GPL"); 64MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>"); 65 66#define SLCAN_MAGIC 0x53CA 67 68static int maxdev = 10; /* MAX number of SLCAN channels; 69 This can be overridden with 70 insmod slcan.ko maxdev=nnn */ 71module_param(maxdev, int, 0); 72MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces"); 73 74/* maximum rx buffer len: extended CAN frame with timestamp */ 75#define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1) 76 77#define SLC_CMD_LEN 1 78#define SLC_SFF_ID_LEN 3 79#define SLC_EFF_ID_LEN 8 80 81struct slcan { 82 int magic; 83 84 /* Various fields. */ 85 struct tty_struct *tty; /* ptr to TTY structure */ 86 struct net_device *dev; /* easy for intr handling */ 87 spinlock_t lock; 88 89 /* These are pointers to the malloc()ed frame buffers. */ 90 unsigned char rbuff[SLC_MTU]; /* receiver buffer */ 91 int rcount; /* received chars counter */ 92 unsigned char xbuff[SLC_MTU]; /* transmitter buffer */ 93 unsigned char *xhead; /* pointer to next XMIT byte */ 94 int xleft; /* bytes left in XMIT queue */ 95 96 unsigned long flags; /* Flag values/ mode etc */ 97#define SLF_INUSE 0 /* Channel in use */ 98#define SLF_ERROR 1 /* Parity, etc. error */ 99}; 100 101static struct net_device **slcan_devs; 102 103 /************************************************************************ 104 * SLCAN ENCAPSULATION FORMAT * 105 ************************************************************************/ 106 107/* 108 * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended 109 * frame format) a data length code (can_dlc) which can be from 0 to 8 110 * and up to <can_dlc> data bytes as payload. 111 * Additionally a CAN frame may become a remote transmission frame if the 112 * RTR-bit is set. This causes another ECU to send a CAN frame with the 113 * given can_id. 114 * 115 * The SLCAN ASCII representation of these different frame types is: 116 * <type> <id> <dlc> <data>* 117 * 118 * Extended frames (29 bit) are defined by capital characters in the type. 119 * RTR frames are defined as 'r' types - normal frames have 't' type: 120 * t => 11 bit data frame 121 * r => 11 bit RTR frame 122 * T => 29 bit data frame 123 * R => 29 bit RTR frame 124 * 125 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64). 126 * The <dlc> is a one byte ASCII number ('0' - '8') 127 * The <data> section has at much ASCII Hex bytes as defined by the <dlc> 128 * 129 * Examples: 130 * 131 * t1230 : can_id 0x123, can_dlc 0, no data 132 * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33 133 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55 134 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request 135 * 136 */ 137 138 /************************************************************************ 139 * STANDARD SLCAN DECAPSULATION * 140 ************************************************************************/ 141 142/* Send one completely decapsulated can_frame to the network layer */ 143static void slc_bump(struct slcan *sl) 144{ 145 struct sk_buff *skb; 146 struct can_frame cf; 147 int i, tmp; 148 u32 tmpid; 149 char *cmd = sl->rbuff; 150 151 cf.can_id = 0; 152 153 switch (*cmd) { 154 case 'r': 155 cf.can_id = CAN_RTR_FLAG; 156 /* fallthrough */ 157 case 't': 158 /* store dlc ASCII value and terminate SFF CAN ID string */ 159 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN]; 160 sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN] = 0; 161 /* point to payload data behind the dlc */ 162 cmd += SLC_CMD_LEN + SLC_SFF_ID_LEN + 1; 163 break; 164 case 'R': 165 cf.can_id = CAN_RTR_FLAG; 166 /* fallthrough */ 167 case 'T': 168 cf.can_id |= CAN_EFF_FLAG; 169 /* store dlc ASCII value and terminate EFF CAN ID string */ 170 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN]; 171 sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN] = 0; 172 /* point to payload data behind the dlc */ 173 cmd += SLC_CMD_LEN + SLC_EFF_ID_LEN + 1; 174 break; 175 default: 176 return; 177 } 178 179 if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid)) 180 return; 181 182 cf.can_id |= tmpid; 183 184 /* get can_dlc from sanitized ASCII value */ 185 if (cf.can_dlc >= '0' && cf.can_dlc < '9') 186 cf.can_dlc -= '0'; 187 else 188 return; 189 190 *(u64 *) (&cf.data) = 0; /* clear payload */ 191 192 /* RTR frames may have a dlc > 0 but they never have any data bytes */ 193 if (!(cf.can_id & CAN_RTR_FLAG)) { 194 for (i = 0; i < cf.can_dlc; i++) { 195 tmp = hex_to_bin(*cmd++); 196 if (tmp < 0) 197 return; 198 cf.data[i] = (tmp << 4); 199 tmp = hex_to_bin(*cmd++); 200 if (tmp < 0) 201 return; 202 cf.data[i] |= tmp; 203 } 204 } 205 206 skb = dev_alloc_skb(sizeof(struct can_frame) + 207 sizeof(struct can_skb_priv)); 208 if (!skb) 209 return; 210 211 skb->dev = sl->dev; 212 skb->protocol = htons(ETH_P_CAN); 213 skb->pkt_type = PACKET_BROADCAST; 214 skb->ip_summed = CHECKSUM_UNNECESSARY; 215 216 can_skb_reserve(skb); 217 can_skb_prv(skb)->ifindex = sl->dev->ifindex; 218 219 memcpy(skb_put(skb, sizeof(struct can_frame)), 220 &cf, sizeof(struct can_frame)); 221 netif_rx_ni(skb); 222 223 sl->dev->stats.rx_packets++; 224 sl->dev->stats.rx_bytes += cf.can_dlc; 225} 226 227/* parse tty input stream */ 228static void slcan_unesc(struct slcan *sl, unsigned char s) 229{ 230 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */ 231 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) && 232 (sl->rcount > 4)) { 233 slc_bump(sl); 234 } 235 sl->rcount = 0; 236 } else { 237 if (!test_bit(SLF_ERROR, &sl->flags)) { 238 if (sl->rcount < SLC_MTU) { 239 sl->rbuff[sl->rcount++] = s; 240 return; 241 } else { 242 sl->dev->stats.rx_over_errors++; 243 set_bit(SLF_ERROR, &sl->flags); 244 } 245 } 246 } 247} 248 249 /************************************************************************ 250 * STANDARD SLCAN ENCAPSULATION * 251 ************************************************************************/ 252 253/* Encapsulate one can_frame and stuff into a TTY queue. */ 254static void slc_encaps(struct slcan *sl, struct can_frame *cf) 255{ 256 int actual, i; 257 unsigned char *pos; 258 unsigned char *endpos; 259 canid_t id = cf->can_id; 260 261 pos = sl->xbuff; 262 263 if (cf->can_id & CAN_RTR_FLAG) 264 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */ 265 else 266 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */ 267 268 /* determine number of chars for the CAN-identifier */ 269 if (cf->can_id & CAN_EFF_FLAG) { 270 id &= CAN_EFF_MASK; 271 endpos = pos + SLC_EFF_ID_LEN; 272 } else { 273 *pos |= 0x20; /* convert R/T to lower case for SFF */ 274 id &= CAN_SFF_MASK; 275 endpos = pos + SLC_SFF_ID_LEN; 276 } 277 278 /* build 3 (SFF) or 8 (EFF) digit CAN identifier */ 279 pos++; 280 while (endpos >= pos) { 281 *endpos-- = hex_asc_upper[id & 0xf]; 282 id >>= 4; 283 } 284 285 pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN; 286 287 *pos++ = cf->can_dlc + '0'; 288 289 /* RTR frames may have a dlc > 0 but they never have any data bytes */ 290 if (!(cf->can_id & CAN_RTR_FLAG)) { 291 for (i = 0; i < cf->can_dlc; i++) 292 pos = hex_byte_pack_upper(pos, cf->data[i]); 293 } 294 295 *pos++ = '\r'; 296 297 /* Order of next two lines is *very* important. 298 * When we are sending a little amount of data, 299 * the transfer may be completed inside the ops->write() 300 * routine, because it's running with interrupts enabled. 301 * In this case we *never* got WRITE_WAKEUP event, 302 * if we did not request it before write operation. 303 * 14 Oct 1994 Dmitry Gorodchanin. 304 */ 305 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); 306 actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff); 307 sl->xleft = (pos - sl->xbuff) - actual; 308 sl->xhead = sl->xbuff + actual; 309 sl->dev->stats.tx_bytes += cf->can_dlc; 310} 311 312/* 313 * Called by the driver when there's room for more data. If we have 314 * more packets to send, we send them here. 315 */ 316static void slcan_write_wakeup(struct tty_struct *tty) 317{ 318 int actual; 319 struct slcan *sl = (struct slcan *) tty->disc_data; 320 321 /* First make sure we're connected. */ 322 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) 323 return; 324 325 spin_lock(&sl->lock); 326 if (sl->xleft <= 0) { 327 /* Now serial buffer is almost free & we can start 328 * transmission of another packet */ 329 sl->dev->stats.tx_packets++; 330 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); 331 spin_unlock(&sl->lock); 332 netif_wake_queue(sl->dev); 333 return; 334 } 335 336 actual = tty->ops->write(tty, sl->xhead, sl->xleft); 337 sl->xleft -= actual; 338 sl->xhead += actual; 339 spin_unlock(&sl->lock); 340} 341 342/* Send a can_frame to a TTY queue. */ 343static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev) 344{ 345 struct slcan *sl = netdev_priv(dev); 346 347 if (skb->len != sizeof(struct can_frame)) 348 goto out; 349 350 spin_lock(&sl->lock); 351 if (!netif_running(dev)) { 352 spin_unlock(&sl->lock); 353 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name); 354 goto out; 355 } 356 if (sl->tty == NULL) { 357 spin_unlock(&sl->lock); 358 goto out; 359 } 360 361 netif_stop_queue(sl->dev); 362 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */ 363 spin_unlock(&sl->lock); 364 365out: 366 kfree_skb(skb); 367 return NETDEV_TX_OK; 368} 369 370 371/****************************************** 372 * Routines looking at netdevice side. 373 ******************************************/ 374 375/* Netdevice UP -> DOWN routine */ 376static int slc_close(struct net_device *dev) 377{ 378 struct slcan *sl = netdev_priv(dev); 379 380 spin_lock_bh(&sl->lock); 381 if (sl->tty) { 382 /* TTY discipline is running. */ 383 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); 384 } 385 netif_stop_queue(dev); 386 sl->rcount = 0; 387 sl->xleft = 0; 388 spin_unlock_bh(&sl->lock); 389 390 return 0; 391} 392 393/* Netdevice DOWN -> UP routine */ 394static int slc_open(struct net_device *dev) 395{ 396 struct slcan *sl = netdev_priv(dev); 397 398 if (sl->tty == NULL) 399 return -ENODEV; 400 401 sl->flags &= (1 << SLF_INUSE); 402 netif_start_queue(dev); 403 return 0; 404} 405 406/* Hook the destructor so we can free slcan devs at the right point in time */ 407static void slc_free_netdev(struct net_device *dev) 408{ 409 int i = dev->base_addr; 410 free_netdev(dev); 411 slcan_devs[i] = NULL; 412} 413 414static int slcan_change_mtu(struct net_device *dev, int new_mtu) 415{ 416 return -EINVAL; 417} 418 419static const struct net_device_ops slc_netdev_ops = { 420 .ndo_open = slc_open, 421 .ndo_stop = slc_close, 422 .ndo_start_xmit = slc_xmit, 423 .ndo_change_mtu = slcan_change_mtu, 424}; 425 426static void slc_setup(struct net_device *dev) 427{ 428 dev->netdev_ops = &slc_netdev_ops; 429 dev->destructor = slc_free_netdev; 430 431 dev->hard_header_len = 0; 432 dev->addr_len = 0; 433 dev->tx_queue_len = 10; 434 435 dev->mtu = sizeof(struct can_frame); 436 dev->type = ARPHRD_CAN; 437 438 /* New-style flags. */ 439 dev->flags = IFF_NOARP; 440 dev->features = NETIF_F_HW_CSUM; 441} 442 443/****************************************** 444 Routines looking at TTY side. 445 ******************************************/ 446 447/* 448 * Handle the 'receiver data ready' interrupt. 449 * This function is called by the 'tty_io' module in the kernel when 450 * a block of SLCAN data has been received, which can now be decapsulated 451 * and sent on to some IP layer for further processing. This will not 452 * be re-entered while running but other ldisc functions may be called 453 * in parallel 454 */ 455 456static void slcan_receive_buf(struct tty_struct *tty, 457 const unsigned char *cp, char *fp, int count) 458{ 459 struct slcan *sl = (struct slcan *) tty->disc_data; 460 461 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) 462 return; 463 464 /* Read the characters out of the buffer */ 465 while (count--) { 466 if (fp && *fp++) { 467 if (!test_and_set_bit(SLF_ERROR, &sl->flags)) 468 sl->dev->stats.rx_errors++; 469 cp++; 470 continue; 471 } 472 slcan_unesc(sl, *cp++); 473 } 474} 475 476/************************************ 477 * slcan_open helper routines. 478 ************************************/ 479 480/* Collect hanged up channels */ 481static void slc_sync(void) 482{ 483 int i; 484 struct net_device *dev; 485 struct slcan *sl; 486 487 for (i = 0; i < maxdev; i++) { 488 dev = slcan_devs[i]; 489 if (dev == NULL) 490 break; 491 492 sl = netdev_priv(dev); 493 if (sl->tty) 494 continue; 495 if (dev->flags & IFF_UP) 496 dev_close(dev); 497 } 498} 499 500/* Find a free SLCAN channel, and link in this `tty' line. */ 501static struct slcan *slc_alloc(dev_t line) 502{ 503 int i; 504 char name[IFNAMSIZ]; 505 struct net_device *dev = NULL; 506 struct slcan *sl; 507 508 for (i = 0; i < maxdev; i++) { 509 dev = slcan_devs[i]; 510 if (dev == NULL) 511 break; 512 513 } 514 515 /* Sorry, too many, all slots in use */ 516 if (i >= maxdev) 517 return NULL; 518 519 sprintf(name, "slcan%d", i); 520 dev = alloc_netdev(sizeof(*sl), name, slc_setup); 521 if (!dev) 522 return NULL; 523 524 dev->base_addr = i; 525 sl = netdev_priv(dev); 526 527 /* Initialize channel control data */ 528 sl->magic = SLCAN_MAGIC; 529 sl->dev = dev; 530 spin_lock_init(&sl->lock); 531 slcan_devs[i] = dev; 532 533 return sl; 534} 535 536/* 537 * Open the high-level part of the SLCAN channel. 538 * This function is called by the TTY module when the 539 * SLCAN line discipline is called for. Because we are 540 * sure the tty line exists, we only have to link it to 541 * a free SLCAN channel... 542 * 543 * Called in process context serialized from other ldisc calls. 544 */ 545 546static int slcan_open(struct tty_struct *tty) 547{ 548 struct slcan *sl; 549 int err; 550 551 if (!capable(CAP_NET_ADMIN)) 552 return -EPERM; 553 554 if (tty->ops->write == NULL) 555 return -EOPNOTSUPP; 556 557 /* RTnetlink lock is misused here to serialize concurrent 558 opens of slcan channels. There are better ways, but it is 559 the simplest one. 560 */ 561 rtnl_lock(); 562 563 /* Collect hanged up channels. */ 564 slc_sync(); 565 566 sl = tty->disc_data; 567 568 err = -EEXIST; 569 /* First make sure we're not already connected. */ 570 if (sl && sl->magic == SLCAN_MAGIC) 571 goto err_exit; 572 573 /* OK. Find a free SLCAN channel to use. */ 574 err = -ENFILE; 575 sl = slc_alloc(tty_devnum(tty)); 576 if (sl == NULL) 577 goto err_exit; 578 579 sl->tty = tty; 580 tty->disc_data = sl; 581 582 if (!test_bit(SLF_INUSE, &sl->flags)) { 583 /* Perform the low-level SLCAN initialization. */ 584 sl->rcount = 0; 585 sl->xleft = 0; 586 587 set_bit(SLF_INUSE, &sl->flags); 588 589 err = register_netdevice(sl->dev); 590 if (err) 591 goto err_free_chan; 592 } 593 594 /* Done. We have linked the TTY line to a channel. */ 595 rtnl_unlock(); 596 tty->receive_room = 65536; /* We don't flow control */ 597 598 /* TTY layer expects 0 on success */ 599 return 0; 600 601err_free_chan: 602 sl->tty = NULL; 603 tty->disc_data = NULL; 604 clear_bit(SLF_INUSE, &sl->flags); 605 606err_exit: 607 rtnl_unlock(); 608 609 /* Count references from TTY module */ 610 return err; 611} 612 613/* 614 * Close down a SLCAN channel. 615 * This means flushing out any pending queues, and then returning. This 616 * call is serialized against other ldisc functions. 617 * 618 * We also use this method for a hangup event. 619 */ 620 621static void slcan_close(struct tty_struct *tty) 622{ 623 struct slcan *sl = (struct slcan *) tty->disc_data; 624 625 /* First make sure we're connected. */ 626 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty) 627 return; 628 629 tty->disc_data = NULL; 630 sl->tty = NULL; 631 632 /* Flush network side */ 633 unregister_netdev(sl->dev); 634 /* This will complete via sl_free_netdev */ 635} 636 637static int slcan_hangup(struct tty_struct *tty) 638{ 639 slcan_close(tty); 640 return 0; 641} 642 643/* Perform I/O control on an active SLCAN channel. */ 644static int slcan_ioctl(struct tty_struct *tty, struct file *file, 645 unsigned int cmd, unsigned long arg) 646{ 647 struct slcan *sl = (struct slcan *) tty->disc_data; 648 unsigned int tmp; 649 650 /* First make sure we're connected. */ 651 if (!sl || sl->magic != SLCAN_MAGIC) 652 return -EINVAL; 653 654 switch (cmd) { 655 case SIOCGIFNAME: 656 tmp = strlen(sl->dev->name) + 1; 657 if (copy_to_user((void __user *)arg, sl->dev->name, tmp)) 658 return -EFAULT; 659 return 0; 660 661 case SIOCSIFHWADDR: 662 return -EINVAL; 663 664 default: 665 return tty_mode_ioctl(tty, file, cmd, arg); 666 } 667} 668 669static struct tty_ldisc_ops slc_ldisc = { 670 .owner = THIS_MODULE, 671 .magic = TTY_LDISC_MAGIC, 672 .name = "slcan", 673 .open = slcan_open, 674 .close = slcan_close, 675 .hangup = slcan_hangup, 676 .ioctl = slcan_ioctl, 677 .receive_buf = slcan_receive_buf, 678 .write_wakeup = slcan_write_wakeup, 679}; 680 681static int __init slcan_init(void) 682{ 683 int status; 684 685 if (maxdev < 4) 686 maxdev = 4; /* Sanity */ 687 688 printk(banner); 689 printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev); 690 691 slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL); 692 if (!slcan_devs) 693 return -ENOMEM; 694 695 /* Fill in our line protocol discipline, and register it */ 696 status = tty_register_ldisc(N_SLCAN, &slc_ldisc); 697 if (status) { 698 printk(KERN_ERR "slcan: can't register line discipline\n"); 699 kfree(slcan_devs); 700 } 701 return status; 702} 703 704static void __exit slcan_exit(void) 705{ 706 int i; 707 struct net_device *dev; 708 struct slcan *sl; 709 unsigned long timeout = jiffies + HZ; 710 int busy = 0; 711 712 if (slcan_devs == NULL) 713 return; 714 715 /* First of all: check for active disciplines and hangup them. 716 */ 717 do { 718 if (busy) 719 msleep_interruptible(100); 720 721 busy = 0; 722 for (i = 0; i < maxdev; i++) { 723 dev = slcan_devs[i]; 724 if (!dev) 725 continue; 726 sl = netdev_priv(dev); 727 spin_lock_bh(&sl->lock); 728 if (sl->tty) { 729 busy++; 730 tty_hangup(sl->tty); 731 } 732 spin_unlock_bh(&sl->lock); 733 } 734 } while (busy && time_before(jiffies, timeout)); 735 736 /* FIXME: hangup is async so we should wait when doing this second 737 phase */ 738 739 for (i = 0; i < maxdev; i++) { 740 dev = slcan_devs[i]; 741 if (!dev) 742 continue; 743 slcan_devs[i] = NULL; 744 745 sl = netdev_priv(dev); 746 if (sl->tty) { 747 printk(KERN_ERR "%s: tty discipline still running\n", 748 dev->name); 749 /* Intentionally leak the control block. */ 750 dev->destructor = NULL; 751 } 752 753 unregister_netdev(dev); 754 } 755 756 kfree(slcan_devs); 757 slcan_devs = NULL; 758 759 i = tty_unregister_ldisc(N_SLCAN); 760 if (i) 761 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i); 762} 763 764module_init(slcan_init); 765module_exit(slcan_exit); 766