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