drivers/net/slip.c

   1 /*
   2  * slip.c       This module implements the SLIP protocol for kernel-based
   3  *              devices like TTY.  It interfaces between a raw TTY, and the
   4  *              kernel's INET protocol layers.
   5  *
   6  * Version:     @(#)slip.c      0.8.3   12/24/94
   7  *
   8  * Authors:     Laurence Culhane, <[email protected]>
   9  *              Fred N. van Kempen, <[email protected]>
  10  *
  11  * Fixes:
  12  *              Alan Cox        :       Sanity checks and avoid tx overruns.
  13  *                                      Has a new sl->mtu field.
  14  *              Alan Cox        :       Found cause of overrun. ifconfig sl0
  15  *                                      mtu upwards. Driver now spots this
  16  *                                      and grows/shrinks its buffers(hack!).
  17  *                                      Memory leak if you run out of memory
  18  *                                      setting up a slip driver fixed.
  19  *              Matt Dillon     :       Printable slip (borrowed from NET2E)
  20  *      Pauline Middelink       :       Slip driver fixes.
  21  *              Alan Cox        :       Honours the old SL_COMPRESSED flag
  22  *              Alan Cox        :       KISS AX.25 and AXUI IP support
  23  *              Michael Riepe   :       Automatic CSLIP recognition added
  24  *              Charles Hedrick :       CSLIP header length problem fix.
  25  *              Alan Cox        :       Corrected non-IP cases of the above.
  26  *              Alan Cox        :       Now uses hardware type as per FvK.
  27  *              Alan Cox        :       Default to 192.168.0.0 (RFC 1597)
  28  *              A.N.Kuznetsov   :       dev_tint() recursion fix.
  29  *      Dmitry Gorodchanin      :       SLIP memory leaks
  30  *      Dmitry Gorodchanin      :       Code cleanup. Reduce tty driver
  31  *                                      buffering from 4096 to 256 bytes.
  32  *                                      Improving SLIP response time.
  33  *                                      CONFIG_SLIP_MODE_SLIP6.
  34  *                                      ifconfig sl? up & down now works
  35  *                                      correctly.
  36  *                                      Modularization.
  37  *              Alan Cox        :       Oops - fix AX.25 buffer lengths
  38  *      Dmitry Gorodchanin      :       Even more cleanups. Preserve CSLIP
  39  *                                      statistics. Include CSLIP code only
  40  *                                      if it really needed.
  41  *              Alan Cox        :       Free slhc buffers in the right place.
  42  *              Alan Cox        :       Allow for digipeated IP over AX.25
  43  *              Matti Aarnio    :       Dynamic SLIP devices, with ideas taken
  44  *                                      from Jim Freeman's <[email protected]>
  45  *                                      dynamic PPP devices.  We do NOT kfree()
  46  *                                      device entries, just reg./unreg. them
  47  *                                      as they are needed.  We kfree() them
  48  *                                      at module cleanup.
  49  *                                      With MODULE-loading ``insmod'', user
  50  *                                      can issue parameter:  slip_maxdev=1024
  51  *                                      (Or how much he/she wants.. Default
  52  *                                      is 256)
  53  *      Stanislav Voronyi       :       Slip line checking, with ideas taken
  54  *                                      from multislip BSDI driver which was
  55  *                                      written by Igor Chechik, RELCOM Corp.
  56  *                                      Only algorithms have been ported to
  57  *                                      Linux SLIP driver.
  58  *      Vitaly E. Lavrov        :       Sane behaviour on tty hangup.
  59  *      Alexey Kuznetsov        :       Cleanup interfaces to tty & netdevice
  60  *                                      modules.
  61  */
  62
  63 #define SL_CHECK_TRANSMIT
  64 #include <linux/module.h>
  65 #include <linux/moduleparam.h>
  66
  67 #include <asm/system.h>
  68 #include <asm/uaccess.h>
  69 #include <linux/bitops.h>
  70 #include <linux/sched.h>
  71 #include <linux/string.h>
  72 #include <linux/mm.h>
  73 #include <linux/interrupt.h>
  74 #include <linux/in.h>
  75 #include <linux/tty.h>
  76 #include <linux/errno.h>
  77 #include <linux/netdevice.h>
  78 #include <linux/etherdevice.h>
  79 #include <linux/skbuff.h>
  80 #include <linux/rtnetlink.h>
  81 #include <linux/if_arp.h>
  82 #include <linux/if_slip.h>
  83 #include <linux/delay.h>
  84 #include <linux/init.h>
  85 #include "slip.h"
  86 #ifdef CONFIG_INET
  87 #include <linux/ip.h>
  88 #include <linux/tcp.h>
  89 #include <net/slhc_vj.h>
  90 #endif
  91
  92 #define SLIP_VERSION    "0.8.4-NET3.019-NEWTTY"
  93
  94 static struct net_device **slip_devs;
  95
  96 static int slip_maxdev = SL_NRUNIT;
  97 module_param(slip_maxdev, int, 0);
  98 MODULE_PARM_DESC(slip_maxdev, "Maximum number of slip devices");
  99
 100 static int slip_esc(unsigned char *p, unsigned char *d, int len);
 101 static void slip_unesc(struct slip *sl, unsigned char c);
 102 #ifdef CONFIG_SLIP_MODE_SLIP6
 103 static int slip_esc6(unsigned char *p, unsigned char *d, int len);
 104 static void slip_unesc6(struct slip *sl, unsigned char c);
 105 #endif
 106 #ifdef CONFIG_SLIP_SMART
 107 static void sl_keepalive(unsigned long sls);
 108 static void sl_outfill(unsigned long sls);
 109 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
 110 #endif
 111
 112 /********************************
 113 *  Buffer administration routines:
 114 *       sl_alloc_bufs()
 115 *       sl_free_bufs()
 116 *       sl_realloc_bufs()
 117 *
 118 * NOTE: sl_realloc_bufs != sl_free_bufs + sl_alloc_bufs, because
 119 *       sl_realloc_bufs provides strong atomicity and reallocation
 120 *       on actively running device.
 121 *********************************/
 122
 123 /*
 124    Allocate channel buffers.
 125  */
 126
 127 static int sl_alloc_bufs(struct slip *sl, int mtu)
 128 {
 129         int err = -ENOBUFS;
 130         unsigned long len;
 131         char *rbuff = NULL;
 132         char *xbuff = NULL;
 133 #ifdef SL_INCLUDE_CSLIP
 134         char *cbuff = NULL;
 135         struct slcompress *slcomp = NULL;
 136 #endif
 137
 138         /*
 139          * Allocate the SLIP frame buffers:
 140          *
 141          * rbuff        Receive buffer.
 142          * xbuff        Transmit buffer.
 143          * cbuff        Temporary compression buffer.
 144          */
 145         len = mtu * 2;
 146
 147         /*
 148          * allow for arrival of larger UDP packets, even if we say not to
 149          * also fixes a bug in which SunOS sends 512-byte packets even with
 150          * an MSS of 128
 151          */
 152         if (len < 576 * 2)
 153                 len = 576 * 2;
 154         rbuff = kmalloc(len + 4, GFP_KERNEL);
 155         if (rbuff == NULL)
 156                 goto err_exit;
 157         xbuff = kmalloc(len + 4, GFP_KERNEL);
 158         if (xbuff == NULL)
 159                 goto err_exit;
 160 #ifdef SL_INCLUDE_CSLIP
 161         cbuff = kmalloc(len + 4, GFP_KERNEL);
 162         if (cbuff == NULL)
 163                 goto err_exit;
 164         slcomp = slhc_init(16, 16);
 165         if (slcomp == NULL)
 166                 goto err_exit;
 167 #endif
 168         spin_lock_bh(&sl->lock);
 169         if (sl->tty == NULL) {
 170                 spin_unlock_bh(&sl->lock);
 171                 err = -ENODEV;
 172                 goto err_exit;
 173         }
 174         sl->mtu      = mtu;
 175         sl->buffsize = len;
 176         sl->rcount   = 0;
 177         sl->xleft    = 0;
 178         rbuff = xchg(&sl->rbuff, rbuff);
 179         xbuff = xchg(&sl->xbuff, xbuff);
 180 #ifdef SL_INCLUDE_CSLIP
 181         cbuff = xchg(&sl->cbuff, cbuff);
 182         slcomp = xchg(&sl->slcomp, slcomp);
 183 #ifdef CONFIG_SLIP_MODE_SLIP6
 184         sl->xdata    = 0;
 185         sl->xbits    = 0;
 186 #endif
 187 #endif
 188         spin_unlock_bh(&sl->lock);
 189         err = 0;
 190
 191         /* Cleanup */
 192 err_exit:
 193 #ifdef SL_INCLUDE_CSLIP
 194         kfree(cbuff);
 195         if (slcomp)
 196                 slhc_free(slcomp);
 197 #endif
 198         kfree(xbuff);
 199         kfree(rbuff);
 200         return err;
 201 }
 202
 203 /* Free a SLIP channel buffers. */
 204 static void sl_free_bufs(struct slip *sl)
 205 {
 206         /* Free all SLIP frame buffers. */
 207         kfree(xchg(&sl->rbuff, NULL));
 208         kfree(xchg(&sl->xbuff, NULL));
 209 #ifdef SL_INCLUDE_CSLIP
 210         kfree(xchg(&sl->cbuff, NULL));
 211         slhc_free(xchg(&sl->slcomp, NULL));
 212 #endif
 213 }
 214
 215 /*
 216    Reallocate slip channel buffers.
 217  */
 218
 219 static int sl_realloc_bufs(struct slip *sl, int mtu)
 220 {
 221         int err = 0;
 222         struct net_device *dev = sl->dev;
 223         unsigned char *xbuff, *rbuff;
 224 #ifdef SL_INCLUDE_CSLIP
 225         unsigned char *cbuff;
 226 #endif
 227         int len = mtu * 2;
 228
 229 /*
 230  * allow for arrival of larger UDP packets, even if we say not to
 231  * also fixes a bug in which SunOS sends 512-byte packets even with
 232  * an MSS of 128
 233  */
 234         if (len < 576 * 2)
 235                 len = 576 * 2;
 236
 237         xbuff = kmalloc(len + 4, GFP_ATOMIC);
 238         rbuff = kmalloc(len + 4, GFP_ATOMIC);
 239 #ifdef SL_INCLUDE_CSLIP
 240         cbuff = kmalloc(len + 4, GFP_ATOMIC);
 241 #endif
 242
 243
 244 #ifdef SL_INCLUDE_CSLIP
 245         if (xbuff == NULL || rbuff == NULL || cbuff == NULL)  {
 246 #else
 247         if (xbuff == NULL || rbuff == NULL)  {
 248 #endif
 249                 if (mtu >= sl->mtu) {
 250                         printk(KERN_WARNING "%s: unable to grow slip buffers, MTU change cancelled.\n",
 251                                dev->name);
 252                         err = -ENOBUFS;
 253                 }
 254                 goto done;
 255         }
 256         spin_lock_bh(&sl->lock);
 257
 258         err = -ENODEV;
 259         if (sl->tty == NULL)
 260                 goto done_on_bh;
 261
 262         xbuff    = xchg(&sl->xbuff, xbuff);
 263         rbuff    = xchg(&sl->rbuff, rbuff);
 264 #ifdef SL_INCLUDE_CSLIP
 265         cbuff    = xchg(&sl->cbuff, cbuff);
 266 #endif
 267         if (sl->xleft)  {
 268                 if (sl->xleft <= len)  {
 269                         memcpy(sl->xbuff, sl->xhead, sl->xleft);
 270                 } else  {
 271                         sl->xleft = 0;
 272                         sl->tx_dropped++;
 273                 }
 274         }
 275         sl->xhead = sl->xbuff;
 276
 277         if (sl->rcount)  {
 278                 if (sl->rcount <= len) {
 279                         memcpy(sl->rbuff, rbuff, sl->rcount);
 280                 } else  {
 281                         sl->rcount = 0;
 282                         sl->rx_over_errors++;
 283                         set_bit(SLF_ERROR, &sl->flags);
 284                 }
 285         }
 286         sl->mtu      = mtu;
 287         dev->mtu      = mtu;
 288         sl->buffsize = len;
 289         err = 0;
 290
 291 done_on_bh:
 292         spin_unlock_bh(&sl->lock);
 293
 294 done:
 295         kfree(xbuff);
 296         kfree(rbuff);
 297 #ifdef SL_INCLUDE_CSLIP
 298         kfree(cbuff);
 299 #endif
 300         return err;
 301 }
 302
 303
 304 /* Set the "sending" flag.  This must be atomic hence the set_bit. */
 305 static inline void sl_lock(struct slip *sl)
 306 {
 307         netif_stop_queue(sl->dev);
 308 }
 309
 310
 311 /* Clear the "sending" flag.  This must be atomic, hence the ASM. */
 312 static inline void sl_unlock(struct slip *sl)
 313 {
 314         netif_wake_queue(sl->dev);
 315 }
 316
 317 /* Send one completely decapsulated IP datagram to the IP layer. */
 318 static void sl_bump(struct slip *sl)
 319 {
 320         struct sk_buff *skb;
 321         int count;
 322
 323         count = sl->rcount;
 324 #ifdef SL_INCLUDE_CSLIP
 325         if (sl->mode & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) {
 326                 unsigned char c = sl->rbuff[0];
 327                 if (c & SL_TYPE_COMPRESSED_TCP) {
 328                         /* ignore compressed packets when CSLIP is off */
 329                         if (!(sl->mode & SL_MODE_CSLIP)) {
 330                                 printk(KERN_WARNING "%s: compressed packet ignored\n", sl->dev->name);
 331                                 return;
 332                         }
 333                         /* make sure we've reserved enough space for uncompress
 334                            to use */
 335                         if (count + 80 > sl->buffsize) {
 336                                 sl->rx_over_errors++;
 337                                 return;
 338                         }
 339                         count = slhc_uncompress(sl->slcomp, sl->rbuff, count);
 340                         if (count <= 0)
 341                                 return;
 342                 } else if (c >= SL_TYPE_UNCOMPRESSED_TCP) {
 343                         if (!(sl->mode & SL_MODE_CSLIP)) {
 344                                 /* turn on header compression */
 345                                 sl->mode |= SL_MODE_CSLIP;
 346                                 sl->mode &= ~SL_MODE_ADAPTIVE;
 347                                 printk(KERN_INFO "%s: header compression turned on\n", sl->dev->name);
 348                         }
 349                         sl->rbuff[0] &= 0x4f;
 350                         if (slhc_remember(sl->slcomp, sl->rbuff, count) <= 0)
 351                                 return;
 352                 }
 353         }
 354 #endif  /* SL_INCLUDE_CSLIP */
 355
 356         sl->rx_bytes += count;
 357
 358         skb = dev_alloc_skb(count);
 359         if (skb == NULL) {
 360                 printk(KERN_WARNING "%s: memory squeeze, dropping packet.\n", sl->dev->name);
 361                 sl->rx_dropped++;
 362                 return;
 363         }
 364         skb->dev = sl->dev;
 365         memcpy(skb_put(skb, count), sl->rbuff, count);
 366         skb_reset_mac_header(skb);
 367         skb->protocol = htons(ETH_P_IP);
 368         netif_rx(skb);
 369         sl->rx_packets++;
 370 }
 371
 372 /* Encapsulate one IP datagram and stuff into a TTY queue. */
 373 static void sl_encaps(struct slip *sl, unsigned char *icp, int len)
 374 {
 375         unsigned char *p;
 376         int actual, count;
 377
 378         if (len > sl->mtu) {            /* Sigh, shouldn't occur BUT ... */
 379                 printk(KERN_WARNING "%s: truncating oversized transmit packet!\n", sl->dev->name);
 380                 sl->tx_dropped++;
 381                 sl_unlock(sl);
 382                 return;
 383         }
 384
 385         p = icp;
 386 #ifdef SL_INCLUDE_CSLIP
 387         if (sl->mode & SL_MODE_CSLIP)
 388                 len = slhc_compress(sl->slcomp, p, len, sl->cbuff, &p, 1);
 389 #endif
 390 #ifdef CONFIG_SLIP_MODE_SLIP6
 391         if (sl->mode & SL_MODE_SLIP6)
 392                 count = slip_esc6(p, (unsigned char *) sl->xbuff, len);
 393         else
 394 #endif
 395                 count = slip_esc(p, (unsigned char *) sl->xbuff, len);
 396
 397         /* Order of next two lines is *very* important.
 398          * When we are sending a little amount of data,
 399          * the transfer may be completed inside the ops->write()
 400          * routine, because it's running with interrupts enabled.
 401          * In this case we *never* got WRITE_WAKEUP event,
 402          * if we did not request it before write operation.
 403          *       14 Oct 1994  Dmitry Gorodchanin.
 404          */
 405         set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 406         actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
 407 #ifdef SL_CHECK_TRANSMIT
 408         sl->dev->trans_start = jiffies;
 409 #endif
 410         sl->xleft = count - actual;
 411         sl->xhead = sl->xbuff + actual;
 412 #ifdef CONFIG_SLIP_SMART
 413         /* VSV */
 414         clear_bit(SLF_OUTWAIT, &sl->flags);     /* reset outfill flag */
 415 #endif
 416 }
 417
 418 /*
 419  * Called by the driver when there's room for more data.  If we have
 420  * more packets to send, we send them here.
 421  */
 422 static void slip_write_wakeup(struct tty_struct *tty)
 423 {
 424         int actual;
 425         struct slip *sl = tty->disc_data;
 426
 427         /* First make sure we're connected. */
 428         if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
 429                 return;
 430
 431         if (sl->xleft <= 0)  {
 432                 /* Now serial buffer is almost free & we can start
 433                  * transmission of another packet */
 434                 sl->tx_packets++;
 435                 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 436                 sl_unlock(sl);
 437                 return;
 438         }
 439
 440         actual = tty->ops->write(tty, sl->xhead, sl->xleft);
 441         sl->xleft -= actual;
 442         sl->xhead += actual;
 443 }
 444
 445 static void sl_tx_timeout(struct net_device *dev)
 446 {
 447         struct slip *sl = netdev_priv(dev);
 448
 449         spin_lock(&sl->lock);
 450
 451         if (netif_queue_stopped(dev)) {
 452                 if (!netif_running(dev))
 453                         goto out;
 454
 455                 /* May be we must check transmitter timeout here ?
 456                  *      14 Oct 1994 Dmitry Gorodchanin.
 457                  */
 458 #ifdef SL_CHECK_TRANSMIT
 459                 if (time_before(jiffies, dev->trans_start + 20 * HZ))  {
 460                         /* 20 sec timeout not reached */
 461                         goto out;
 462                 }
 463                 printk(KERN_WARNING "%s: transmit timed out, %s?\n",
 464                         dev->name,
 465                         (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
 466                                 "bad line quality" : "driver error");
 467                 sl->xleft = 0;
 468                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 469                 sl_unlock(sl);
 470 #endif
 471         }
 472 out:
 473         spin_unlock(&sl->lock);
 474 }
 475
 476
 477 /* Encapsulate an IP datagram and kick it into a TTY queue. */
 478 static netdev_tx_t
 479 sl_xmit(struct sk_buff *skb, struct net_device *dev)
 480 {
 481         struct slip *sl = netdev_priv(dev);
 482
 483         spin_lock(&sl->lock);
 484         if (!netif_running(dev)) {
 485                 spin_unlock(&sl->lock);
 486                 printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name);
 487                 dev_kfree_skb(skb);
 488                 return NETDEV_TX_OK;
 489         }
 490         if (sl->tty == NULL) {
 491                 spin_unlock(&sl->lock);
 492                 dev_kfree_skb(skb);
 493                 return NETDEV_TX_OK;
 494         }
 495
 496         sl_lock(sl);
 497         sl->tx_bytes += skb->len;
 498         sl_encaps(sl, skb->data, skb->len);
 499         spin_unlock(&sl->lock);
 500
 501         dev_kfree_skb(skb);
 502         return NETDEV_TX_OK;
 503 }
 504
 505
 506 /******************************************
 507  *   Routines looking at netdevice side.
 508  ******************************************/
 509
 510 /* Netdevice UP -> DOWN routine */
 511
 512 static int
 513 sl_close(struct net_device *dev)
 514 {
 515         struct slip *sl = netdev_priv(dev);
 516
 517         spin_lock_bh(&sl->lock);
 518         if (sl->tty)
 519                 /* TTY discipline is running. */
 520                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 521         netif_stop_queue(dev);
 522         sl->rcount   = 0;
 523         sl->xleft    = 0;
 524         spin_unlock_bh(&sl->lock);
 525
 526         return 0;
 527 }
 528
 529 /* Netdevice DOWN -> UP routine */
 530
 531 static int sl_open(struct net_device *dev)
 532 {
 533         struct slip *sl = netdev_priv(dev);
 534
 535         if (sl->tty == NULL)
 536                 return -ENODEV;
 537
 538         sl->flags &= (1 << SLF_INUSE);
 539         netif_start_queue(dev);
 540         return 0;
 541 }
 542
 543 /* Netdevice change MTU request */
 544
 545 static int sl_change_mtu(struct net_device *dev, int new_mtu)
 546 {
 547         struct slip *sl = netdev_priv(dev);
 548
 549         if (new_mtu < 68 || new_mtu > 65534)
 550                 return -EINVAL;
 551
 552         if (new_mtu != dev->mtu)
 553                 return sl_realloc_bufs(sl, new_mtu);
 554         return 0;
 555 }
 556
 557 /* Netdevice get statistics request */
 558
 559 static struct net_device_stats *
 560 sl_get_stats(struct net_device *dev)
 561 {
 562         static struct net_device_stats stats;
 563         struct slip *sl = netdev_priv(dev);
 564 #ifdef SL_INCLUDE_CSLIP
 565         struct slcompress *comp;
 566 #endif
 567
 568         memset(&stats, 0, sizeof(struct net_device_stats));
 569
 570         stats.rx_packets     = sl->rx_packets;
 571         stats.tx_packets     = sl->tx_packets;
 572         stats.rx_bytes       = sl->rx_bytes;
 573         stats.tx_bytes       = sl->tx_bytes;
 574         stats.rx_dropped     = sl->rx_dropped;
 575         stats.tx_dropped     = sl->tx_dropped;
 576         stats.tx_errors      = sl->tx_errors;
 577         stats.rx_errors      = sl->rx_errors;
 578         stats.rx_over_errors = sl->rx_over_errors;
 579 #ifdef SL_INCLUDE_CSLIP
 580         stats.rx_fifo_errors = sl->rx_compressed;
 581         stats.tx_fifo_errors = sl->tx_compressed;
 582         stats.collisions     = sl->tx_misses;
 583         comp = sl->slcomp;
 584         if (comp) {
 585                 stats.rx_fifo_errors += comp->sls_i_compressed;
 586                 stats.rx_dropped     += comp->sls_i_tossed;
 587                 stats.tx_fifo_errors += comp->sls_o_compressed;
 588                 stats.collisions     += comp->sls_o_misses;
 589         }
 590 #endif /* CONFIG_INET */
 591         return (&stats);
 592 }
 593
 594 /* Netdevice register callback */
 595
 596 static int sl_init(struct net_device *dev)
 597 {
 598         struct slip *sl = netdev_priv(dev);
 599
 600         /*
 601          *      Finish setting up the DEVICE info.
 602          */
 603
 604         dev->mtu                = sl->mtu;
 605         dev->type               = ARPHRD_SLIP + sl->mode;
 606 #ifdef SL_CHECK_TRANSMIT
 607         dev->watchdog_timeo     = 20*HZ;
 608 #endif
 609         return 0;
 610 }
 611
 612
 613 static void sl_uninit(struct net_device *dev)
 614 {
 615         struct slip *sl = netdev_priv(dev);
 616
 617         sl_free_bufs(sl);
 618 }
 619
 620 /* Hook the destructor so we can free slip devices at the right point in time */
 621 static void sl_free_netdev(struct net_device *dev)
 622 {
 623         int i = dev->base_addr;
 624         free_netdev(dev);
 625         slip_devs[i] = NULL;
 626 }
 627
 628 static const struct net_device_ops sl_netdev_ops = {
 629         .ndo_init               = sl_init,
 630         .ndo_uninit             = sl_uninit,
 631         .ndo_open               = sl_open,
 632         .ndo_stop               = sl_close,
 633         .ndo_start_xmit         = sl_xmit,
 634         .ndo_get_stats          = sl_get_stats,
 635         .ndo_change_mtu         = sl_change_mtu,
 636         .ndo_tx_timeout         = sl_tx_timeout,
 637 #ifdef CONFIG_SLIP_SMART
 638         .ndo_do_ioctl           = sl_ioctl,
 639 #endif
 640 };
 641
 642
 643 static void sl_setup(struct net_device *dev)
 644 {
 645         dev->netdev_ops         = &sl_netdev_ops;
 646         dev->destructor         = sl_free_netdev;
 647
 648         dev->hard_header_len    = 0;
 649         dev->addr_len           = 0;
 650         dev->tx_queue_len       = 10;
 651
 652         /* New-style flags. */
 653         dev->flags              = IFF_NOARP|IFF_POINTOPOINT|IFF_MULTICAST;
 654 }
 655
 656 /******************************************
 657   Routines looking at TTY side.
 658  ******************************************/
 659
 660
 661 /*
 662  * Handle the 'receiver data ready' interrupt.
 663  * This function is called by the 'tty_io' module in the kernel when
 664  * a block of SLIP data has been received, which can now be decapsulated
 665  * and sent on to some IP layer for further processing. This will not
 666  * be re-entered while running but other ldisc functions may be called
 667  * in parallel
 668  */
 669
 670 static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 671                                                         char *fp, int count)
 672 {
 673         struct slip *sl = tty->disc_data;
 674
 675         if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
 676                 return;
 677
 678         /* Read the characters out of the buffer */
 679         while (count--) {
 680                 if (fp && *fp++) {
 681                         if (!test_and_set_bit(SLF_ERROR, &sl->flags))
 682                                 sl->rx_errors++;
 683                         cp++;
 684                         continue;
 685                 }
 686 #ifdef CONFIG_SLIP_MODE_SLIP6
 687                 if (sl->mode & SL_MODE_SLIP6)
 688                         slip_unesc6(sl, *cp++);
 689                 else
 690 #endif
 691                         slip_unesc(sl, *cp++);
 692         }
 693 }
 694
 695 /************************************
 696  *  slip_open helper routines.
 697  ************************************/
 698
 699 /* Collect hanged up channels */
 700 static void sl_sync(void)
 701 {
 702         int i;
 703         struct net_device *dev;
 704         struct slip       *sl;
 705
 706         for (i = 0; i < slip_maxdev; i++) {
 707                 dev = slip_devs[i];
 708                 if (dev == NULL)
 709                         break;
 710
 711                 sl = netdev_priv(dev);
 712                 if (sl->tty || sl->leased)
 713                         continue;
 714                 if (dev->flags & IFF_UP)
 715                         dev_close(dev);
 716         }
 717 }
 718
 719
 720 /* Find a free SLIP channel, and link in this `tty' line. */
 721 static struct slip *sl_alloc(dev_t line)
 722 {
 723         int i;
 724         struct net_device *dev = NULL;
 725         struct slip       *sl;
 726
 727         if (slip_devs == NULL)
 728                 return NULL;    /* Master array missing ! */
 729
 730         for (i = 0; i < slip_maxdev; i++) {
 731                 dev = slip_devs[i];
 732                 if (dev == NULL)
 733                         break;
 734         }
 735         /* Sorry, too many, all slots in use */
 736         if (i >= slip_maxdev)
 737                 return NULL;
 738
 739         if (dev) {
 740                 sl = netdev_priv(dev);
 741                 if (test_bit(SLF_INUSE, &sl->flags)) {
 742                         unregister_netdevice(dev);
 743                         dev = NULL;
 744                         slip_devs[i] = NULL;
 745                 }
 746         }
 747
 748         if (!dev) {
 749                 char name[IFNAMSIZ];
 750                 sprintf(name, "sl%d", i);
 751
 752                 dev = alloc_netdev(sizeof(*sl), name, sl_setup);
 753                 if (!dev)
 754                         return NULL;
 755                 dev->base_addr  = i;
 756         }
 757
 758         sl = netdev_priv(dev);
 759
 760         /* Initialize channel control data */
 761         sl->magic       = SLIP_MAGIC;
 762         sl->dev         = dev;
 763         spin_lock_init(&sl->lock);
 764         sl->mode        = SL_MODE_DEFAULT;
 765 #ifdef CONFIG_SLIP_SMART
 766         /* initialize timer_list struct */
 767         init_timer(&sl->keepalive_timer);
 768         sl->keepalive_timer.data = (unsigned long)sl;
 769         sl->keepalive_timer.function = sl_keepalive;
 770         init_timer(&sl->outfill_timer);
 771         sl->outfill_timer.data = (unsigned long)sl;
 772         sl->outfill_timer.function = sl_outfill;
 773 #endif
 774         slip_devs[i] = dev;
 775         return sl;
 776 }
 777
 778 /*
 779  * Open the high-level part of the SLIP channel.
 780  * This function is called by the TTY module when the
 781  * SLIP line discipline is called for.  Because we are
 782  * sure the tty line exists, we only have to link it to
 783  * a free SLIP channel...
 784  *
 785  * Called in process context serialized from other ldisc calls.
 786  */
 787
 788 static int slip_open(struct tty_struct *tty)
 789 {
 790         struct slip *sl;
 791         int err;
 792
 793         if (!capable(CAP_NET_ADMIN))
 794                 return -EPERM;
 795
 796         if (tty->ops->write == NULL)
 797                 return -EOPNOTSUPP;
 798
 799         /* RTnetlink lock is misused here to serialize concurrent
 800            opens of slip channels. There are better ways, but it is
 801            the simplest one.
 802          */
 803         rtnl_lock();
 804
 805         /* Collect hanged up channels. */
 806         sl_sync();
 807
 808         sl = tty->disc_data;
 809
 810         err = -EEXIST;
 811         /* First make sure we're not already connected. */
 812         if (sl && sl->magic == SLIP_MAGIC)
 813                 goto err_exit;
 814
 815         /* OK.  Find a free SLIP channel to use. */
 816         err = -ENFILE;
 817         sl = sl_alloc(tty_devnum(tty));
 818         if (sl == NULL)
 819                 goto err_exit;
 820
 821         sl->tty = tty;
 822         tty->disc_data = sl;
 823         sl->line = tty_devnum(tty);
 824         sl->pid = current->pid;
 825
 826         if (!test_bit(SLF_INUSE, &sl->flags)) {
 827                 /* Perform the low-level SLIP initialization. */
 828                 err = sl_alloc_bufs(sl, SL_MTU);
 829                 if (err)
 830                         goto err_free_chan;
 831
 832                 set_bit(SLF_INUSE, &sl->flags);
 833
 834                 err = register_netdevice(sl->dev);
 835                 if (err)
 836                         goto err_free_bufs;
 837         }
 838
 839 #ifdef CONFIG_SLIP_SMART
 840         if (sl->keepalive) {
 841                 sl->keepalive_timer.expires = jiffies + sl->keepalive * HZ;
 842                 add_timer(&sl->keepalive_timer);
 843         }
 844         if (sl->outfill) {
 845                 sl->outfill_timer.expires = jiffies + sl->outfill * HZ;
 846                 add_timer(&sl->outfill_timer);
 847         }
 848 #endif
 849
 850         /* Done.  We have linked the TTY line to a channel. */
 851         rtnl_unlock();
 852         tty->receive_room = 65536;      /* We don't flow control */
 853         return sl->dev->base_addr;
 854
 855 err_free_bufs:
 856         sl_free_bufs(sl);
 857
 858 err_free_chan:
 859         sl->tty = NULL;
 860         tty->disc_data = NULL;
 861         clear_bit(SLF_INUSE, &sl->flags);
 862
 863 err_exit:
 864         rtnl_unlock();
 865
 866         /* Count references from TTY module */
 867         return err;
 868 }
 869
 870 /*
 871  * Close down a SLIP channel.
 872  * This means flushing out any pending queues, and then returning. This
 873  * call is serialized against other ldisc functions.
 874  *
 875  * We also use this method fo a hangup event
 876  */
 877
 878 static void slip_close(struct tty_struct *tty)
 879 {
 880         struct slip *sl = tty->disc_data;
 881
 882         /* First make sure we're connected. */
 883         if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty)
 884                 return;
 885
 886         tty->disc_data = NULL;
 887         sl->tty = NULL;
 888         if (!sl->leased)
 889                 sl->line = 0;
 890
 891         /* VSV = very important to remove timers */
 892 #ifdef CONFIG_SLIP_SMART
 893         del_timer_sync(&sl->keepalive_timer);
 894         del_timer_sync(&sl->outfill_timer);
 895 #endif
 896         /* Flush network side */
 897         unregister_netdev(sl->dev);
 898         /* This will complete via sl_free_netdev */
 899 }
 900
 901 static int slip_hangup(struct tty_struct *tty)
 902 {
 903         slip_close(tty);
 904         return 0;
 905 }
 906  /************************************************************************
 907   *                     STANDARD SLIP ENCAPSULATION                      *
 908   ************************************************************************/
 909
 910 static int slip_esc(unsigned char *s, unsigned char *d, int len)
 911 {
 912         unsigned char *ptr = d;
 913         unsigned char c;
 914
 915         /*
 916          * Send an initial END character to flush out any
 917          * data that may have accumulated in the receiver
 918          * due to line noise.
 919          */
 920
 921         *ptr++ = END;
 922
 923         /*
 924          * For each byte in the packet, send the appropriate
 925          * character sequence, according to the SLIP protocol.
 926          */
 927
 928         while (len-- > 0) {
 929                 switch (c = *s++) {
 930                 case END:
 931                         *ptr++ = ESC;
 932                         *ptr++ = ESC_END;
 933                         break;
 934                 case ESC:
 935                         *ptr++ = ESC;
 936                         *ptr++ = ESC_ESC;
 937                         break;
 938                 default:
 939                         *ptr++ = c;
 940                         break;
 941                 }
 942         }
 943         *ptr++ = END;
 944         return (ptr - d);
 945 }
 946
 947 static void slip_unesc(struct slip *sl, unsigned char s)
 948 {
 949
 950         switch (s) {
 951         case END:
 952 #ifdef CONFIG_SLIP_SMART
 953                 /* drop keeptest bit = VSV */
 954                 if (test_bit(SLF_KEEPTEST, &sl->flags))
 955                         clear_bit(SLF_KEEPTEST, &sl->flags);
 956 #endif
 957
 958                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags)
 959                                                         && (sl->rcount > 2))
 960                         sl_bump(sl);
 961                 clear_bit(SLF_ESCAPE, &sl->flags);
 962                 sl->rcount = 0;
 963                 return;
 964
 965         case ESC:
 966                 set_bit(SLF_ESCAPE, &sl->flags);
 967                 return;
 968         case ESC_ESC:
 969                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 970                         s = ESC;
 971                 break;
 972         case ESC_END:
 973                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 974                         s = END;
 975                 break;
 976         }
 977         if (!test_bit(SLF_ERROR, &sl->flags))  {
 978                 if (sl->rcount < sl->buffsize)  {
 979                         sl->rbuff[sl->rcount++] = s;
 980                         return;
 981                 }
 982                 sl->rx_over_errors++;
 983                 set_bit(SLF_ERROR, &sl->flags);
 984         }
 985 }
 986
 987
 988 #ifdef CONFIG_SLIP_MODE_SLIP6
 989 /************************************************************************
 990  *                       6 BIT SLIP ENCAPSULATION                       *
 991  ************************************************************************/
 992
 993 static int slip_esc6(unsigned char *s, unsigned char *d, int len)
 994 {
 995         unsigned char *ptr = d;
 996         unsigned char c;
 997         int i;
 998         unsigned short v = 0;
 999         short bits = 0;
1000
1001         /*
1002          * Send an initial END character to flush out any
1003          * data that may have accumulated in the receiver
1004          * due to line noise.
1005          */
1006
1007         *ptr++ = 0x70;
1008
1009         /*
1010          * Encode the packet into printable ascii characters
1011          */
1012
1013         for (i = 0; i < len; ++i) {
1014                 v = (v << 8) | s[i];
1015                 bits += 8;
1016                 while (bits >= 6) {
1017                         bits -= 6;
1018                         c = 0x30 + ((v >> bits) & 0x3F);
1019                         *ptr++ = c;
1020                 }
1021         }
1022         if (bits) {
1023                 c = 0x30 + ((v << (6 - bits)) & 0x3F);
1024                 *ptr++ = c;
1025         }
1026         *ptr++ = 0x70;
1027         return ptr - d;
1028 }
1029
1030 static void slip_unesc6(struct slip *sl, unsigned char s)
1031 {
1032         unsigned char c;
1033
1034         if (s == 0x70) {
1035 #ifdef CONFIG_SLIP_SMART
1036                 /* drop keeptest bit = VSV */
1037                 if (test_bit(SLF_KEEPTEST, &sl->flags))
1038                         clear_bit(SLF_KEEPTEST, &sl->flags);
1039 #endif
1040
1041                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags)
1042                                                         && (sl->rcount > 2))
1043                         sl_bump(sl);
1044                 sl->rcount = 0;
1045                 sl->xbits = 0;
1046                 sl->xdata = 0;
1047         } else if (s >= 0x30 && s < 0x70) {
1048                 sl->xdata = (sl->xdata << 6) | ((s - 0x30) & 0x3F);
1049                 sl->xbits += 6;
1050                 if (sl->xbits >= 8) {
1051                         sl->xbits -= 8;
1052                         c = (unsigned char)(sl->xdata >> sl->xbits);
1053                         if (!test_bit(SLF_ERROR, &sl->flags))  {
1054                                 if (sl->rcount < sl->buffsize)  {
1055                                         sl->rbuff[sl->rcount++] = c;
1056                                         return;
1057                                 }
1058                                 sl->rx_over_errors++;
1059                                 set_bit(SLF_ERROR, &sl->flags);
1060                         }
1061                 }
1062         }
1063 }
1064 #endif /* CONFIG_SLIP_MODE_SLIP6 */
1065
1066 /* Perform I/O control on an active SLIP channel. */
1067 static int slip_ioctl(struct tty_struct *tty, struct file *file,
1068                                         unsigned int cmd, unsigned long arg)
1069 {
1070         struct slip *sl = tty->disc_data;
1071         unsigned int tmp;
1072         int __user *p = (int __user *)arg;
1073
1074         /* First make sure we're connected. */
1075         if (!sl || sl->magic != SLIP_MAGIC)
1076                 return -EINVAL;
1077
1078         switch (cmd) {
1079         case SIOCGIFNAME:
1080                 tmp = strlen(sl->dev->name) + 1;
1081                 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
1082                         return -EFAULT;
1083                 return 0;
1084
1085         case SIOCGIFENCAP:
1086                 if (put_user(sl->mode, p))
1087                         return -EFAULT;
1088                 return 0;
1089
1090         case SIOCSIFENCAP:
1091                 if (get_user(tmp, p))
1092                         return -EFAULT;
1093 #ifndef SL_INCLUDE_CSLIP
1094                 if (tmp & (SL_MODE_CSLIP|SL_MODE_ADAPTIVE))
1095                         return -EINVAL;
1096 #else
1097                 if ((tmp & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) ==
1098                     (SL_MODE_ADAPTIVE | SL_MODE_CSLIP))
1099                         /* return -EINVAL; */
1100                         tmp &= ~SL_MODE_ADAPTIVE;
1101 #endif
1102 #ifndef CONFIG_SLIP_MODE_SLIP6
1103                 if (tmp & SL_MODE_SLIP6)
1104                         return -EINVAL;
1105 #endif
1106                 sl->mode = tmp;
1107                 sl->dev->type = ARPHRD_SLIP + sl->mode;
1108                 return 0;
1109
1110         case SIOCSIFHWADDR:
1111                 return -EINVAL;
1112
1113 #ifdef CONFIG_SLIP_SMART
1114         /* VSV changes start here */
1115         case SIOCSKEEPALIVE:
1116                 if (get_user(tmp, p))
1117                         return -EFAULT;
1118                 if (tmp > 255) /* max for unchar */
1119                         return -EINVAL;
1120
1121                 spin_lock_bh(&sl->lock);
1122                 if (!sl->tty) {
1123                         spin_unlock_bh(&sl->lock);
1124                         return -ENODEV;
1125                 }
1126                 sl->keepalive = (u8)tmp;
1127                 if (sl->keepalive != 0) {
1128                         mod_timer(&sl->keepalive_timer,
1129                                         jiffies + sl->keepalive * HZ);
1130                         set_bit(SLF_KEEPTEST, &sl->flags);
1131                 } else
1132                         del_timer(&sl->keepalive_timer);
1133                 spin_unlock_bh(&sl->lock);
1134                 return 0;
1135
1136         case SIOCGKEEPALIVE:
1137                 if (put_user(sl->keepalive, p))
1138                         return -EFAULT;
1139                 return 0;
1140
1141         case SIOCSOUTFILL:
1142                 if (get_user(tmp, p))
1143                         return -EFAULT;
1144                 if (tmp > 255) /* max for unchar */
1145                         return -EINVAL;
1146                 spin_lock_bh(&sl->lock);
1147                 if (!sl->tty) {
1148                         spin_unlock_bh(&sl->lock);
1149                         return -ENODEV;
1150                 }
1151                 sl->outfill = (u8)tmp;
1152                 if (sl->outfill != 0) {
1153                         mod_timer(&sl->outfill_timer,
1154                                                 jiffies + sl->outfill * HZ);
1155                         set_bit(SLF_OUTWAIT, &sl->flags);
1156                 } else
1157                         del_timer(&sl->outfill_timer);
1158                 spin_unlock_bh(&sl->lock);
1159                 return 0;
1160
1161         case SIOCGOUTFILL:
1162                 if (put_user(sl->outfill, p))
1163                         return -EFAULT;
1164                 return 0;
1165         /* VSV changes end */
1166 #endif
1167         default:
1168                 return tty_mode_ioctl(tty, file, cmd, arg);
1169         }
1170 }
1171
1172 /* VSV changes start here */
1173 #ifdef CONFIG_SLIP_SMART
1174 /* function do_ioctl called from net/core/dev.c
1175    to allow get/set outfill/keepalive parameter
1176    by ifconfig                                 */
1177
1178 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
1179 {
1180         struct slip *sl = netdev_priv(dev);
1181         unsigned long *p = (unsigned long *)&rq->ifr_ifru;
1182
1183         if (sl == NULL)         /* Allocation failed ?? */
1184                 return -ENODEV;
1185
1186         spin_lock_bh(&sl->lock);
1187
1188         if (!sl->tty) {
1189                 spin_unlock_bh(&sl->lock);
1190                 return -ENODEV;
1191         }
1192
1193         switch (cmd) {
1194         case SIOCSKEEPALIVE:
1195                 /* max for unchar */
1196                 if ((unsigned)*p > 255) {
1197                         spin_unlock_bh(&sl->lock);
1198                         return -EINVAL;
1199                 }
1200                 sl->keepalive = (u8)*p;
1201                 if (sl->keepalive != 0) {
1202                         sl->keepalive_timer.expires =
1203                                                 jiffies + sl->keepalive * HZ;
1204                         mod_timer(&sl->keepalive_timer,
1205                                                 jiffies + sl->keepalive * HZ);
1206                         set_bit(SLF_KEEPTEST, &sl->flags);
1207                 } else
1208                         del_timer(&sl->keepalive_timer);
1209                 break;
1210
1211         case SIOCGKEEPALIVE:
1212                 *p = sl->keepalive;
1213                 break;
1214
1215         case SIOCSOUTFILL:
1216                 if ((unsigned)*p > 255) { /* max for unchar */
1217                         spin_unlock_bh(&sl->lock);
1218                         return -EINVAL;
1219                 }
1220                 sl->outfill = (u8)*p;
1221                 if (sl->outfill != 0) {
1222                         mod_timer(&sl->outfill_timer,
1223                                                 jiffies + sl->outfill * HZ);
1224                         set_bit(SLF_OUTWAIT, &sl->flags);
1225                 } else
1226                         del_timer(&sl->outfill_timer);
1227                 break;
1228
1229         case SIOCGOUTFILL:
1230                 *p = sl->outfill;
1231                 break;
1232
1233         case SIOCSLEASE:
1234                 /* Resolve race condition, when ioctl'ing hanged up
1235                    and opened by another process device.
1236                  */
1237                 if (sl->tty != current->signal->tty &&
1238                                                 sl->pid != current->pid) {
1239                         spin_unlock_bh(&sl->lock);
1240                         return -EPERM;
1241                 }
1242                 sl->leased = 0;
1243                 if (*p)
1244                         sl->leased = 1;
1245                 break;
1246
1247         case SIOCGLEASE:
1248                 *p = sl->leased;
1249         };
1250         spin_unlock_bh(&sl->lock);
1251         return 0;
1252 }
1253 #endif
1254 /* VSV changes end */
1255
1256 static struct tty_ldisc_ops sl_ldisc = {
1257         .owner          = THIS_MODULE,
1258         .magic          = TTY_LDISC_MAGIC,
1259         .name           = "slip",
1260         .open           = slip_open,
1261         .close          = slip_close,
1262         .hangup         = slip_hangup,
1263         .ioctl          = slip_ioctl,
1264         .receive_buf    = slip_receive_buf,
1265         .write_wakeup   = slip_write_wakeup,
1266 };
1267
1268 static int __init slip_init(void)
1269 {
1270         int status;
1271
1272         if (slip_maxdev < 4)
1273                 slip_maxdev = 4; /* Sanity */
1274
1275         printk(KERN_INFO "SLIP: version %s (dynamic channels, max=%d)"
1276 #ifdef CONFIG_SLIP_MODE_SLIP6
1277                " (6 bit encapsulation enabled)"
1278 #endif
1279                ".\n",
1280                SLIP_VERSION, slip_maxdev);
1281 #if defined(SL_INCLUDE_CSLIP)
1282         printk(KERN_INFO "CSLIP: code copyright 1989 Regents of the University of California.\n");
1283 #endif
1284 #ifdef CONFIG_SLIP_SMART
1285         printk(KERN_INFO "SLIP linefill/keepalive option.\n");
1286 #endif
1287
1288         slip_devs = kzalloc(sizeof(struct net_device *)*slip_maxdev,
1289                                                                 GFP_KERNEL);
1290         if (!slip_devs) {
1291                 printk(KERN_ERR "SLIP: Can't allocate slip devices array.\n");
1292                 return -ENOMEM;
1293         }
1294
1295         /* Fill in our line protocol discipline, and register it */
1296         status = tty_register_ldisc(N_SLIP, &sl_ldisc);
1297         if (status != 0) {
1298                 printk(KERN_ERR "SLIP: can't register line discipline (err = %d)\n", status);
1299                 kfree(slip_devs);
1300         }
1301         return status;
1302 }
1303
1304 static void __exit slip_exit(void)
1305 {
1306         int i;
1307         struct net_device *dev;
1308         struct slip *sl;
1309         unsigned long timeout = jiffies + HZ;
1310         int busy = 0;
1311
1312         if (slip_devs == NULL)
1313                 return;
1314
1315         /* First of all: check for active disciplines and hangup them.
1316          */
1317         do {
1318                 if (busy)
1319                         msleep_interruptible(100);
1320
1321                 busy = 0;
1322                 for (i = 0; i < slip_maxdev; i++) {
1323                         dev = slip_devs[i];
1324                         if (!dev)
1325                                 continue;
1326                         sl = netdev_priv(dev);
1327                         spin_lock_bh(&sl->lock);
1328                         if (sl->tty) {
1329                                 busy++;
1330                                 tty_hangup(sl->tty);
1331                         }
1332                         spin_unlock_bh(&sl->lock);
1333                 }
1334         } while (busy && time_before(jiffies, timeout));
1335
1336         /* FIXME: hangup is async so we should wait when doing this second
1337            phase */
1338
1339         for (i = 0; i < slip_maxdev; i++) {
1340                 dev = slip_devs[i];
1341                 if (!dev)
1342                         continue;
1343                 slip_devs[i] = NULL;
1344
1345                 sl = netdev_priv(dev);
1346                 if (sl->tty) {
1347                         printk(KERN_ERR "%s: tty discipline still running\n",
1348                                dev->name);
1349                         /* Intentionally leak the control block. */
1350                         dev->destructor = NULL;
1351                 }
1352
1353                 unregister_netdev(dev);
1354         }
1355
1356         kfree(slip_devs);
1357         slip_devs = NULL;
1358
1359         i = tty_unregister_ldisc(N_SLIP);
1360         if (i != 0)
1361                 printk(KERN_ERR "SLIP: can't unregister line discipline (err = %d)\n", i);
1362 }
1363
1364 module_init(slip_init);
1365 module_exit(slip_exit);
1366
1367 #ifdef CONFIG_SLIP_SMART
1368 /*
1369  * This is start of the code for multislip style line checking
1370  * added by Stanislav Voronyi. All changes before marked VSV
1371  */
1372
1373 static void sl_outfill(unsigned long sls)
1374 {
1375         struct slip *sl = (struct slip *)sls;
1376
1377         spin_lock(&sl->lock);
1378
1379         if (sl->tty == NULL)
1380                 goto out;
1381
1382         if (sl->outfill) {
1383                 if (test_bit(SLF_OUTWAIT, &sl->flags)) {
1384                         /* no packets were transmitted, do outfill */
1385 #ifdef CONFIG_SLIP_MODE_SLIP6
1386                         unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END;
1387 #else
1388                         unsigned char s = END;
1389 #endif
1390                         /* put END into tty queue. Is it right ??? */
1391                         if (!netif_queue_stopped(sl->dev)) {
1392                                 /* if device busy no outfill */
1393                                 sl->tty->ops->write(sl->tty, &s, 1);
1394                         }
1395                 } else
1396                         set_bit(SLF_OUTWAIT, &sl->flags);
1397
1398                 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
1399         }
1400 out:
1401         spin_unlock(&sl->lock);
1402 }
1403
1404 static void sl_keepalive(unsigned long sls)
1405 {
1406         struct slip *sl = (struct slip *)sls;
1407
1408         spin_lock(&sl->lock);
1409
1410         if (sl->tty == NULL)
1411                 goto out;
1412
1413         if (sl->keepalive) {
1414                 if (test_bit(SLF_KEEPTEST, &sl->flags)) {
1415                         /* keepalive still high :(, we must hangup */
1416                         if (sl->outfill)
1417                                 /* outfill timer must be deleted too */
1418                                 (void)del_timer(&sl->outfill_timer);
1419                         printk(KERN_DEBUG "%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name);
1420                         /* this must hangup tty & close slip */
1421                         tty_hangup(sl->tty);
1422                         /* I think we need not something else */
1423                         goto out;
1424                 } else
1425                         set_bit(SLF_KEEPTEST, &sl->flags);
1426
1427                 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
1428         }
1429 out:
1430         spin_unlock(&sl->lock);
1431 }
1432
1433 #endif
1434 MODULE_LICENSE("GPL");
1435 MODULE_ALIAS_LDISC(N_SLIP);