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   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, <loz@holmes.demon.co.uk>
   9  *              Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
  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 <jfree@caldera.com>
  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/compat.h>
  84 #include <linux/delay.h>
  85 #include <linux/init.h>
  86 #include <linux/slab.h>
  87 #include "slip.h"
  88 #ifdef CONFIG_INET
  89 #include <linux/ip.h>
  90 #include <linux/tcp.h>
  91 #include <net/slhc_vj.h>
  92 #endif
  93
  94 #define SLIP_VERSION    "0.8.4-NET3.019-NEWTTY"
  95
  96 static struct net_device **slip_devs;
  97
  98 static int slip_maxdev = SL_NRUNIT;
  99 module_param(slip_maxdev, int, 0);
 100 MODULE_PARM_DESC(slip_maxdev, "Maximum number of slip devices");
 101
 102 static int slip_esc(unsigned char *p, unsigned char *d, int len);
 103 static void slip_unesc(struct slip *sl, unsigned char c);
 104 #ifdef CONFIG_SLIP_MODE_SLIP6
 105 static int slip_esc6(unsigned char *p, unsigned char *d, int len);
 106 static void slip_unesc6(struct slip *sl, unsigned char c);
 107 #endif
 108 #ifdef CONFIG_SLIP_SMART
 109 static void sl_keepalive(unsigned long sls);
 110 static void sl_outfill(unsigned long sls);
 111 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
 112 #endif
 113
 114 /********************************
 115 *  Buffer administration routines:
 116 *       sl_alloc_bufs()
 117 *       sl_free_bufs()
 118 *       sl_realloc_bufs()
 119 *
 120 * NOTE: sl_realloc_bufs != sl_free_bufs + sl_alloc_bufs, because
 121 *       sl_realloc_bufs provides strong atomicity and reallocation
 122 *       on actively running device.
 123 *********************************/
 124
 125 /*
 126    Allocate channel buffers.
 127  */
 128
 129 static int sl_alloc_bufs(struct slip *sl, int mtu)
 130 {
 131         int err = -ENOBUFS;
 132         unsigned long len;
 133         char *rbuff = NULL;
 134         char *xbuff = NULL;
 135 #ifdef SL_INCLUDE_CSLIP
 136         char *cbuff = NULL;
 137         struct slcompress *slcomp = NULL;
 138 #endif
 139
 140         /*
 141          * Allocate the SLIP frame buffers:
 142          *
 143          * rbuff        Receive buffer.
 144          * xbuff        Transmit buffer.
 145          * cbuff        Temporary compression buffer.
 146          */
 147         len = mtu * 2;
 148
 149         /*
 150          * allow for arrival of larger UDP packets, even if we say not to
 151          * also fixes a bug in which SunOS sends 512-byte packets even with
 152          * an MSS of 128
 153          */
 154         if (len < 576 * 2)
 155                 len = 576 * 2;
 156         rbuff = kmalloc(len + 4, GFP_KERNEL);
 157         if (rbuff == NULL)
 158                 goto err_exit;
 159         xbuff = kmalloc(len + 4, GFP_KERNEL);
 160         if (xbuff == NULL)
 161                 goto err_exit;
 162 #ifdef SL_INCLUDE_CSLIP
 163         cbuff = kmalloc(len + 4, GFP_KERNEL);
 164         if (cbuff == NULL)
 165                 goto err_exit;
 166         slcomp = slhc_init(16, 16);
 167         if (slcomp == NULL)
 168                 goto err_exit;
 169 #endif
 170         spin_lock_bh(&sl->lock);
 171         if (sl->tty == NULL) {
 172                 spin_unlock_bh(&sl->lock);
 173                 err = -ENODEV;
 174                 goto err_exit;
 175         }
 176         sl->mtu      = mtu;
 177         sl->buffsize = len;
 178         sl->rcount   = 0;
 179         sl->xleft    = 0;
 180         rbuff = xchg(&sl->rbuff, rbuff);
 181         xbuff = xchg(&sl->xbuff, xbuff);
 182 #ifdef SL_INCLUDE_CSLIP
 183         cbuff = xchg(&sl->cbuff, cbuff);
 184         slcomp = xchg(&sl->slcomp, slcomp);
 185 #ifdef CONFIG_SLIP_MODE_SLIP6
 186         sl->xdata    = 0;
 187         sl->xbits    = 0;
 188 #endif
 189 #endif
 190         spin_unlock_bh(&sl->lock);
 191         err = 0;
 192
 193         /* Cleanup */
 194 err_exit:
 195 #ifdef SL_INCLUDE_CSLIP
 196         kfree(cbuff);
 197         if (slcomp)
 198                 slhc_free(slcomp);
 199 #endif
 200         kfree(xbuff);
 201         kfree(rbuff);
 202         return err;
 203 }
 204
 205 /* Free a SLIP channel buffers. */
 206 static void sl_free_bufs(struct slip *sl)
 207 {
 208         /* Free all SLIP frame buffers. */
 209         kfree(xchg(&sl->rbuff, NULL));
 210         kfree(xchg(&sl->xbuff, NULL));
 211 #ifdef SL_INCLUDE_CSLIP
 212         kfree(xchg(&sl->cbuff, NULL));
 213         slhc_free(xchg(&sl->slcomp, NULL));
 214 #endif
 215 }
 216
 217 /*
 218    Reallocate slip channel buffers.
 219  */
 220
 221 static int sl_realloc_bufs(struct slip *sl, int mtu)
 222 {
 223         int err = 0;
 224         struct net_device *dev = sl->dev;
 225         unsigned char *xbuff, *rbuff;
 226 #ifdef SL_INCLUDE_CSLIP
 227         unsigned char *cbuff;
 228 #endif
 229         int len = mtu * 2;
 230
 231 /*
 232  * allow for arrival of larger UDP packets, even if we say not to
 233  * also fixes a bug in which SunOS sends 512-byte packets even with
 234  * an MSS of 128
 235  */
 236         if (len < 576 * 2)
 237                 len = 576 * 2;
 238
 239         xbuff = kmalloc(len + 4, GFP_ATOMIC);
 240         rbuff = kmalloc(len + 4, GFP_ATOMIC);
 241 #ifdef SL_INCLUDE_CSLIP
 242         cbuff = kmalloc(len + 4, GFP_ATOMIC);
 243 #endif
 244
 245
 246 #ifdef SL_INCLUDE_CSLIP
 247         if (xbuff == NULL || rbuff == NULL || cbuff == NULL)  {
 248 #else
 249         if (xbuff == NULL || rbuff == NULL)  {
 250 #endif
 251                 if (mtu >= sl->mtu) {
 252                         printk(KERN_WARNING "%s: unable to grow slip buffers, MTU change cancelled.\n",
 253                                dev->name);
 254                         err = -ENOBUFS;
 255                 }
 256                 goto done;
 257         }
 258         spin_lock_bh(&sl->lock);
 259
 260         err = -ENODEV;
 261         if (sl->tty == NULL)
 262                 goto done_on_bh;
 263
 264         xbuff    = xchg(&sl->xbuff, xbuff);
 265         rbuff    = xchg(&sl->rbuff, rbuff);
 266 #ifdef SL_INCLUDE_CSLIP
 267         cbuff    = xchg(&sl->cbuff, cbuff);
 268 #endif
 269         if (sl->xleft)  {
 270                 if (sl->xleft <= len)  {
 271                         memcpy(sl->xbuff, sl->xhead, sl->xleft);
 272                 } else  {
 273                         sl->xleft = 0;
 274                         sl->tx_dropped++;
 275                 }
 276         }
 277         sl->xhead = sl->xbuff;
 278
 279         if (sl->rcount)  {
 280                 if (sl->rcount <= len) {
 281                         memcpy(sl->rbuff, rbuff, sl->rcount);
 282                 } else  {
 283                         sl->rcount = 0;
 284                         sl->rx_over_errors++;
 285                         set_bit(SLF_ERROR, &sl->flags);
 286                 }
 287         }
 288         sl->mtu      = mtu;
 289         dev->mtu      = mtu;
 290         sl->buffsize = len;
 291         err = 0;
 292
 293 done_on_bh:
 294         spin_unlock_bh(&sl->lock);
 295
 296 done:
 297         kfree(xbuff);
 298         kfree(rbuff);
 299 #ifdef SL_INCLUDE_CSLIP
 300         kfree(cbuff);
 301 #endif
 302         return err;
 303 }
 304
 305
 306 /* Set the "sending" flag.  This must be atomic hence the set_bit. */
 307 static inline void sl_lock(struct slip *sl)
 308 {
 309         netif_stop_queue(sl->dev);
 310 }
 311
 312
 313 /* Clear the "sending" flag.  This must be atomic, hence the ASM. */
 314 static inline void sl_unlock(struct slip *sl)
 315 {
 316         netif_wake_queue(sl->dev);
 317 }
 318
 319 /* Send one completely decapsulated IP datagram to the IP layer. */
 320 static void sl_bump(struct slip *sl)
 321 {
 322         struct sk_buff *skb;
 323         int count;
 324
 325         count = sl->rcount;
 326 #ifdef SL_INCLUDE_CSLIP
 327         if (sl->mode & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) {
 328                 unsigned char c = sl->rbuff[0];
 329                 if (c & SL_TYPE_COMPRESSED_TCP) {
 330                         /* ignore compressed packets when CSLIP is off */
 331                         if (!(sl->mode & SL_MODE_CSLIP)) {
 332                                 printk(KERN_WARNING "%s: compressed packet ignored\n", sl->dev->name);
 333                                 return;
 334                         }
 335                         /* make sure we've reserved enough space for uncompress
 336                            to use */
 337                         if (count + 80 > sl->buffsize) {
 338                                 sl->rx_over_errors++;
 339                                 return;
 340                         }
 341                         count = slhc_uncompress(sl->slcomp, sl->rbuff, count);
 342                         if (count <= 0)
 343                                 return;
 344                 } else if (c >= SL_TYPE_UNCOMPRESSED_TCP) {
 345                         if (!(sl->mode & SL_MODE_CSLIP)) {
 346                                 /* turn on header compression */
 347                                 sl->mode |= SL_MODE_CSLIP;
 348                                 sl->mode &= ~SL_MODE_ADAPTIVE;
 349                                 printk(KERN_INFO "%s: header compression turned on\n", sl->dev->name);
 350                         }
 351                         sl->rbuff[0] &= 0x4f;
 352                         if (slhc_remember(sl->slcomp, sl->rbuff, count) <= 0)
 353                                 return;
 354                 }
 355         }
 356 #endif  /* SL_INCLUDE_CSLIP */
 357
 358         sl->rx_bytes += count;
 359
 360         skb = dev_alloc_skb(count);
 361         if (skb == NULL) {
 362                 printk(KERN_WARNING "%s: memory squeeze, dropping packet.\n", sl->dev->name);
 363                 sl->rx_dropped++;
 364                 return;
 365         }
 366         skb->dev = sl->dev;
 367         memcpy(skb_put(skb, count), sl->rbuff, count);
 368         skb_reset_mac_header(skb);
 369         skb->protocol = htons(ETH_P_IP);
 370         netif_rx(skb);
 371         sl->rx_packets++;
 372 }
 373
 374 /* Encapsulate one IP datagram and stuff into a TTY queue. */
 375 static void sl_encaps(struct slip *sl, unsigned char *icp, int len)
 376 {
 377         unsigned char *p;
 378         int actual, count;
 379
 380         if (len > sl->mtu) {            /* Sigh, shouldn't occur BUT ... */
 381                 printk(KERN_WARNING "%s: truncating oversized transmit packet!\n", sl->dev->name);
 382                 sl->tx_dropped++;
 383                 sl_unlock(sl);
 384                 return;
 385         }
 386
 387         p = icp;
 388 #ifdef SL_INCLUDE_CSLIP
 389         if (sl->mode & SL_MODE_CSLIP)
 390                 len = slhc_compress(sl->slcomp, p, len, sl->cbuff, &p, 1);
 391 #endif
 392 #ifdef CONFIG_SLIP_MODE_SLIP6
 393         if (sl->mode & SL_MODE_SLIP6)
 394                 count = slip_esc6(p, (unsigned char *) sl->xbuff, len);
 395         else
 396 #endif
 397                 count = slip_esc(p, (unsigned char *) sl->xbuff, len);
 398
 399         /* Order of next two lines is *very* important.
 400          * When we are sending a little amount of data,
 401          * the transfer may be completed inside the ops->write()
 402          * routine, because it's running with interrupts enabled.
 403          * In this case we *never* got WRITE_WAKEUP event,
 404          * if we did not request it before write operation.
 405          *       14 Oct 1994  Dmitry Gorodchanin.
 406          */
 407         set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 408         actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
 409 #ifdef SL_CHECK_TRANSMIT
 410         sl->dev->trans_start = jiffies;
 411 #endif
 412         sl->xleft = count - actual;
 413         sl->xhead = sl->xbuff + actual;
 414 #ifdef CONFIG_SLIP_SMART
 415         /* VSV */
 416         clear_bit(SLF_OUTWAIT, &sl->flags);     /* reset outfill flag */
 417 #endif
 418 }
 419
 420 /*
 421  * Called by the driver when there's room for more data.  If we have
 422  * more packets to send, we send them here.
 423  */
 424 static void slip_write_wakeup(struct tty_struct *tty)
 425 {
 426         int actual;
 427         struct slip *sl = tty->disc_data;
 428
 429         /* First make sure we're connected. */
 430         if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
 431                 return;
 432
 433         if (sl->xleft <= 0)  {
 434                 /* Now serial buffer is almost free & we can start
 435                  * transmission of another packet */
 436                 sl->tx_packets++;
 437                 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 438                 sl_unlock(sl);
 439                 return;
 440         }
 441
 442         actual = tty->ops->write(tty, sl->xhead, sl->xleft);
 443         sl->xleft -= actual;
 444         sl->xhead += actual;
 445 }
 446
 447 static void sl_tx_timeout(struct net_device *dev)
 448 {
 449         struct slip *sl = netdev_priv(dev);
 450
 451         spin_lock(&sl->lock);
 452
 453         if (netif_queue_stopped(dev)) {
 454                 if (!netif_running(dev))
 455                         goto out;
 456
 457                 /* May be we must check transmitter timeout here ?
 458                  *      14 Oct 1994 Dmitry Gorodchanin.
 459                  */
 460 #ifdef SL_CHECK_TRANSMIT
 461                 if (time_before(jiffies, dev_trans_start(dev) + 20 * HZ))  {
 462                         /* 20 sec timeout not reached */
 463                         goto out;
 464                 }
 465                 printk(KERN_WARNING "%s: transmit timed out, %s?\n",
 466                         dev->name,
 467                         (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
 468                                 "bad line quality" : "driver error");
 469                 sl->xleft = 0;
 470                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 471                 sl_unlock(sl);
 472 #endif
 473         }
 474 out:
 475         spin_unlock(&sl->lock);
 476 }
 477
 478
 479 /* Encapsulate an IP datagram and kick it into a TTY queue. */
 480 static netdev_tx_t
 481 sl_xmit(struct sk_buff *skb, struct net_device *dev)
 482 {
 483         struct slip *sl = netdev_priv(dev);
 484
 485         spin_lock(&sl->lock);
 486         if (!netif_running(dev)) {
 487                 spin_unlock(&sl->lock);
 488                 printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name);
 489                 dev_kfree_skb(skb);
 490                 return NETDEV_TX_OK;
 491         }
 492         if (sl->tty == NULL) {
 493                 spin_unlock(&sl->lock);
 494                 dev_kfree_skb(skb);
 495                 return NETDEV_TX_OK;
 496         }
 497
 498         sl_lock(sl);
 499         sl->tx_bytes += skb->len;
 500         sl_encaps(sl, skb->data, skb->len);
 501         spin_unlock(&sl->lock);
 502
 503         dev_kfree_skb(skb);
 504         return NETDEV_TX_OK;
 505 }
 506
 507
 508 /******************************************
 509  *   Routines looking at netdevice side.
 510  ******************************************/
 511
 512 /* Netdevice UP -> DOWN routine */
 513
 514 static int
 515 sl_close(struct net_device *dev)
 516 {
 517         struct slip *sl = netdev_priv(dev);
 518
 519         spin_lock_bh(&sl->lock);
 520         if (sl->tty)
 521                 /* TTY discipline is running. */
 522                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 523         netif_stop_queue(dev);
 524         sl->rcount   = 0;
 525         sl->xleft    = 0;
 526         spin_unlock_bh(&sl->lock);
 527
 528         return 0;
 529 }
 530
 531 /* Netdevice DOWN -> UP routine */
 532
 533 static int sl_open(struct net_device *dev)
 534 {
 535         struct slip *sl = netdev_priv(dev);
 536
 537         if (sl->tty == NULL)
 538                 return -ENODEV;
 539
 540         sl->flags &= (1 << SLF_INUSE);
 541         netif_start_queue(dev);
 542         return 0;
 543 }
 544
 545 /* Netdevice change MTU request */
 546
 547 static int sl_change_mtu(struct net_device *dev, int new_mtu)
 548 {
 549         struct slip *sl = netdev_priv(dev);
 550
 551         if (new_mtu < 68 || new_mtu > 65534)
 552                 return -EINVAL;
 553
 554         if (new_mtu != dev->mtu)
 555                 return sl_realloc_bufs(sl, new_mtu);
 556         return 0;
 557 }
 558
 559 /* Netdevice get statistics request */
 560
 561 static struct net_device_stats *
 562 sl_get_stats(struct net_device *dev)
 563 {
 564         static struct net_device_stats stats;
 565         struct slip *sl = netdev_priv(dev);
 566 #ifdef SL_INCLUDE_CSLIP
 567         struct slcompress *comp;
 568 #endif
 569
 570         memset(&stats, 0, sizeof(struct net_device_stats));
 571
 572         stats.rx_packets     = sl->rx_packets;
 573         stats.tx_packets     = sl->tx_packets;
 574         stats.rx_bytes       = sl->rx_bytes;
 575         stats.tx_bytes       = sl->tx_bytes;
 576         stats.rx_dropped     = sl->rx_dropped;
 577         stats.tx_dropped     = sl->tx_dropped;
 578         stats.tx_errors      = sl->tx_errors;
 579         stats.rx_errors      = sl->rx_errors;
 580         stats.rx_over_errors = sl->rx_over_errors;
 581 #ifdef SL_INCLUDE_CSLIP
 582         stats.rx_fifo_errors = sl->rx_compressed;
 583         stats.tx_fifo_errors = sl->tx_compressed;
 584         stats.collisions     = sl->tx_misses;
 585         comp = sl->slcomp;
 586         if (comp) {
 587                 stats.rx_fifo_errors += comp->sls_i_compressed;
 588                 stats.rx_dropped     += comp->sls_i_tossed;
 589                 stats.tx_fifo_errors += comp->sls_o_compressed;
 590                 stats.collisions     += comp->sls_o_misses;
 591         }
 592 #endif /* CONFIG_INET */
 593         return (&stats);
 594 }
 595
 596 /* Netdevice register callback */
 597
 598 static int sl_init(struct net_device *dev)
 599 {
 600         struct slip *sl = netdev_priv(dev);
 601
 602         /*
 603          *      Finish setting up the DEVICE info.
 604          */
 605
 606         dev->mtu                = sl->mtu;
 607         dev->type               = ARPHRD_SLIP + sl->mode;
 608 #ifdef SL_CHECK_TRANSMIT
 609         dev->watchdog_timeo     = 20*HZ;
 610 #endif
 611         return 0;
 612 }
 613
 614
 615 static void sl_uninit(struct net_device *dev)
 616 {
 617         struct slip *sl = netdev_priv(dev);
 618
 619         sl_free_bufs(sl);
 620 }
 621
 622 /* Hook the destructor so we can free slip devices at the right point in time */
 623 static void sl_free_netdev(struct net_device *dev)
 624 {
 625         int i = dev->base_addr;
 626         free_netdev(dev);
 627         slip_devs[i] = NULL;
 628 }
 629
 630 static const struct net_device_ops sl_netdev_ops = {
 631         .ndo_init               = sl_init,
 632         .ndo_uninit             = sl_uninit,
 633         .ndo_open               = sl_open,
 634         .ndo_stop               = sl_close,
 635         .ndo_start_xmit         = sl_xmit,
 636         .ndo_get_stats          = sl_get_stats,
 637         .ndo_change_mtu         = sl_change_mtu,
 638         .ndo_tx_timeout         = sl_tx_timeout,
 639 #ifdef CONFIG_SLIP_SMART
 640         .ndo_do_ioctl           = sl_ioctl,
 641 #endif
 642 };
 643
 644
 645 static void sl_setup(struct net_device *dev)
 646 {
 647         dev->netdev_ops         = &sl_netdev_ops;
 648         dev->destructor         = sl_free_netdev;
 649
 650         dev->hard_header_len    = 0;
 651         dev->addr_len           = 0;
 652         dev->tx_queue_len       = 10;
 653
 654         /* New-style flags. */
 655         dev->flags              = IFF_NOARP|IFF_POINTOPOINT|IFF_MULTICAST;
 656 }
 657
 658 /******************************************
 659   Routines looking at TTY side.
 660  ******************************************/
 661
 662
 663 /*
 664  * Handle the 'receiver data ready' interrupt.
 665  * This function is called by the 'tty_io' module in the kernel when
 666  * a block of SLIP data has been received, which can now be decapsulated
 667  * and sent on to some IP layer for further processing. This will not
 668  * be re-entered while running but other ldisc functions may be called
 669  * in parallel
 670  */
 671
 672 static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 673                                                         char *fp, int count)
 674 {
 675         struct slip *sl = tty->disc_data;
 676
 677         if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
 678                 return;
 679
 680         /* Read the characters out of the buffer */
 681         while (count--) {
 682                 if (fp && *fp++) {
 683                         if (!test_and_set_bit(SLF_ERROR, &sl->flags))
 684                                 sl->rx_errors++;
 685                         cp++;
 686                         continue;
 687                 }
 688 #ifdef CONFIG_SLIP_MODE_SLIP6
 689                 if (sl->mode & SL_MODE_SLIP6)
 690                         slip_unesc6(sl, *cp++);
 691                 else
 692 #endif
 693                         slip_unesc(sl, *cp++);
 694         }
 695 }
 696
 697 /************************************
 698  *  slip_open helper routines.
 699  ************************************/
 700
 701 /* Collect hanged up channels */
 702 static void sl_sync(void)
 703 {
 704         int i;
 705         struct net_device *dev;
 706         struct slip       *sl;
 707
 708         for (i = 0; i < slip_maxdev; i++) {
 709                 dev = slip_devs[i];
 710                 if (dev == NULL)
 711                         break;
 712
 713                 sl = netdev_priv(dev);
 714                 if (sl->tty || sl->leased)
 715                         continue;
 716                 if (dev->flags & IFF_UP)
 717                         dev_close(dev);
 718         }
 719 }
 720
 721
 722 /* Find a free SLIP channel, and link in this `tty' line. */
 723 static struct slip *sl_alloc(dev_t line)
 724 {
 725         int i;
 726         struct net_device *dev = NULL;
 727         struct slip       *sl;
 728
 729         if (slip_devs == NULL)
 730                 return NULL;    /* Master array missing ! */
 731
 732         for (i = 0; i < slip_maxdev; i++) {
 733                 dev = slip_devs[i];
 734                 if (dev == NULL)
 735                         break;
 736         }
 737         /* Sorry, too many, all slots in use */
 738         if (i >= slip_maxdev)
 739                 return NULL;
 740
 741         if (dev) {
 742                 sl = netdev_priv(dev);
 743                 if (test_bit(SLF_INUSE, &sl->flags)) {
 744                         unregister_netdevice(dev);
 745                         dev = NULL;
 746                         slip_devs[i] = NULL;
 747                 }
 748         }
 749
 750         if (!dev) {
 751                 char name[IFNAMSIZ];
 752                 sprintf(name, "sl%d", i);
 753
 754                 dev = alloc_netdev(sizeof(*sl), name, sl_setup);
 755                 if (!dev)
 756                         return NULL;
 757                 dev->base_addr  = i;
 758         }
 759
 760         sl = netdev_priv(dev);
 761
 762         /* Initialize channel control data */
 763         sl->magic       = SLIP_MAGIC;
 764         sl->dev         = dev;
 765         spin_lock_init(&sl->lock);
 766         sl->mode        = SL_MODE_DEFAULT;
 767 #ifdef CONFIG_SLIP_SMART
 768         /* initialize timer_list struct */
 769         init_timer(&sl->keepalive_timer);
 770         sl->keepalive_timer.data = (unsigned long)sl;
 771         sl->keepalive_timer.function = sl_keepalive;
 772         init_timer(&sl->outfill_timer);
 773         sl->outfill_timer.data = (unsigned long)sl;
 774         sl->outfill_timer.function = sl_outfill;
 775 #endif
 776         slip_devs[i] = dev;
 777         return sl;
 778 }
 779
 780 /*
 781  * Open the high-level part of the SLIP channel.
 782  * This function is called by the TTY module when the
 783  * SLIP line discipline is called for.  Because we are
 784  * sure the tty line exists, we only have to link it to
 785  * a free SLIP channel...
 786  *
 787  * Called in process context serialized from other ldisc calls.
 788  */
 789
 790 static int slip_open(struct tty_struct *tty)
 791 {
 792         struct slip *sl;
 793         int err;
 794
 795         if (!capable(CAP_NET_ADMIN))
 796                 return -EPERM;
 797
 798         if (tty->ops->write == NULL)
 799                 return -EOPNOTSUPP;
 800
 801         /* RTnetlink lock is misused here to serialize concurrent
 802            opens of slip channels. There are better ways, but it is
 803            the simplest one.
 804          */
 805         rtnl_lock();
 806
 807         /* Collect hanged up channels. */
 808         sl_sync();
 809
 810         sl = tty->disc_data;
 811
 812         err = -EEXIST;
 813         /* First make sure we're not already connected. */
 814         if (sl && sl->magic == SLIP_MAGIC)
 815                 goto err_exit;
 816
 817         /* OK.  Find a free SLIP channel to use. */
 818         err = -ENFILE;
 819         sl = sl_alloc(tty_devnum(tty));
 820         if (sl == NULL)
 821                 goto err_exit;
 822
 823         sl->tty = tty;
 824         tty->disc_data = sl;
 825         sl->line = tty_devnum(tty);
 826         sl->pid = current->pid;
 827
 828         if (!test_bit(SLF_INUSE, &sl->flags)) {
 829                 /* Perform the low-level SLIP initialization. */
 830                 err = sl_alloc_bufs(sl, SL_MTU);
 831                 if (err)
 832                         goto err_free_chan;
 833
 834                 set_bit(SLF_INUSE, &sl->flags);
 835
 836                 err = register_netdevice(sl->dev);
 837                 if (err)
 838                         goto err_free_bufs;
 839         }
 840
 841 #ifdef CONFIG_SLIP_SMART
 842         if (sl->keepalive) {
 843                 sl->keepalive_timer.expires = jiffies + sl->keepalive * HZ;
 844                 add_timer(&sl->keepalive_timer);
 845         }
 846         if (sl->outfill) {
 847                 sl->outfill_timer.expires = jiffies + sl->outfill * HZ;
 848                 add_timer(&sl->outfill_timer);
 849         }
 850 #endif
 851
 852         /* Done.  We have linked the TTY line to a channel. */
 853         rtnl_unlock();
 854         tty->receive_room = 65536;      /* We don't flow control */
 855         return sl->dev->base_addr;
 856
 857 err_free_bufs:
 858         sl_free_bufs(sl);
 859
 860 err_free_chan:
 861         sl->tty = NULL;
 862         tty->disc_data = NULL;
 863         clear_bit(SLF_INUSE, &sl->flags);
 864
 865 err_exit:
 866         rtnl_unlock();
 867
 868         /* Count references from TTY module */
 869         return err;
 870 }
 871
 872 /*
 873  * Close down a SLIP channel.
 874  * This means flushing out any pending queues, and then returning. This
 875  * call is serialized against other ldisc functions.
 876  *
 877  * We also use this method fo a hangup event
 878  */
 879
 880 static void slip_close(struct tty_struct *tty)
 881 {
 882         struct slip *sl = tty->disc_data;
 883
 884         /* First make sure we're connected. */
 885         if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty)
 886                 return;
 887
 888         tty->disc_data = NULL;
 889         sl->tty = NULL;
 890         if (!sl->leased)
 891                 sl->line = 0;
 892
 893         /* VSV = very important to remove timers */
 894 #ifdef CONFIG_SLIP_SMART
 895         del_timer_sync(&sl->keepalive_timer);
 896         del_timer_sync(&sl->outfill_timer);
 897 #endif
 898         /* Flush network side */
 899         unregister_netdev(sl->dev);
 900         /* This will complete via sl_free_netdev */
 901 }
 902
 903 static int slip_hangup(struct tty_struct *tty)
 904 {
 905         slip_close(tty);
 906         return 0;
 907 }
 908  /************************************************************************
 909   *                     STANDARD SLIP ENCAPSULATION                      *
 910   ************************************************************************/
 911
 912 static int slip_esc(unsigned char *s, unsigned char *d, int len)
 913 {
 914         unsigned char *ptr = d;
 915         unsigned char c;
 916
 917         /*
 918          * Send an initial END character to flush out any
 919          * data that may have accumulated in the receiver
 920          * due to line noise.
 921          */
 922
 923         *ptr++ = END;
 924
 925         /*
 926          * For each byte in the packet, send the appropriate
 927          * character sequence, according to the SLIP protocol.
 928          */
 929
 930         while (len-- > 0) {
 931                 switch (c = *s++) {
 932                 case END:
 933                         *ptr++ = ESC;
 934                         *ptr++ = ESC_END;
 935                         break;
 936                 case ESC:
 937                         *ptr++ = ESC;
 938                         *ptr++ = ESC_ESC;
 939                         break;
 940                 default:
 941                         *ptr++ = c;
 942                         break;
 943                 }
 944         }
 945         *ptr++ = END;
 946         return (ptr - d);
 947 }
 948
 949 static void slip_unesc(struct slip *sl, unsigned char s)
 950 {
 951
 952         switch (s) {
 953         case END:
 954 #ifdef CONFIG_SLIP_SMART
 955                 /* drop keeptest bit = VSV */
 956                 if (test_bit(SLF_KEEPTEST, &sl->flags))
 957                         clear_bit(SLF_KEEPTEST, &sl->flags);
 958 #endif
 959
 960                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
 961                     (sl->rcount > 2))
 962                         sl_bump(sl);
 963                 clear_bit(SLF_ESCAPE, &sl->flags);
 964                 sl->rcount = 0;
 965                 return;
 966
 967         case ESC:
 968                 set_bit(SLF_ESCAPE, &sl->flags);
 969                 return;
 970         case ESC_ESC:
 971                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 972                         s = ESC;
 973                 break;
 974         case ESC_END:
 975                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 976                         s = END;
 977                 break;
 978         }
 979         if (!test_bit(SLF_ERROR, &sl->flags))  {
 980                 if (sl->rcount < sl->buffsize)  {
 981                         sl->rbuff[sl->rcount++] = s;
 982                         return;
 983                 }
 984                 sl->rx_over_errors++;
 985                 set_bit(SLF_ERROR, &sl->flags);
 986         }
 987 }
 988
 989
 990 #ifdef CONFIG_SLIP_MODE_SLIP6
 991 /************************************************************************
 992  *                       6 BIT SLIP ENCAPSULATION                       *
 993  ************************************************************************/
 994
 995 static int slip_esc6(unsigned char *s, unsigned char *d, int len)
 996 {
 997         unsigned char *ptr = d;
 998         unsigned char c;
 999         int i;
1000         unsigned short v = 0;
1001         short bits = 0;
1002
1003         /*
1004          * Send an initial END character to flush out any
1005          * data that may have accumulated in the receiver
1006          * due to line noise.
1007          */
1008
1009         *ptr++ = 0x70;
1010
1011         /*
1012          * Encode the packet into printable ascii characters
1013          */
1014
1015         for (i = 0; i < len; ++i) {
1016                 v = (v << 8) | s[i];
1017                 bits += 8;
1018                 while (bits >= 6) {
1019                         bits -= 6;
1020                         c = 0x30 + ((v >> bits) & 0x3F);
1021                         *ptr++ = c;
1022                 }
1023         }
1024         if (bits) {
1025                 c = 0x30 + ((v << (6 - bits)) & 0x3F);
1026                 *ptr++ = c;
1027         }
1028         *ptr++ = 0x70;
1029         return ptr - d;
1030 }
1031
1032 static void slip_unesc6(struct slip *sl, unsigned char s)
1033 {
1034         unsigned char c;
1035
1036         if (s == 0x70) {
1037 #ifdef CONFIG_SLIP_SMART
1038                 /* drop keeptest bit = VSV */
1039                 if (test_bit(SLF_KEEPTEST, &sl->flags))
1040                         clear_bit(SLF_KEEPTEST, &sl->flags);
1041 #endif
1042
1043                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
1044                     (sl->rcount > 2))
1045                         sl_bump(sl);
1046                 sl->rcount = 0;
1047                 sl->xbits = 0;
1048                 sl->xdata = 0;
1049         } else if (s >= 0x30 && s < 0x70) {
1050                 sl->xdata = (sl->xdata << 6) | ((s - 0x30) & 0x3F);
1051                 sl->xbits += 6;
1052                 if (sl->xbits >= 8) {
1053                         sl->xbits -= 8;
1054                         c = (unsigned char)(sl->xdata >> sl->xbits);
1055                         if (!test_bit(SLF_ERROR, &sl->flags))  {
1056                                 if (sl->rcount < sl->buffsize)  {
1057                                         sl->rbuff[sl->rcount++] = c;
1058                                         return;
1059                                 }
1060                                 sl->rx_over_errors++;
1061                                 set_bit(SLF_ERROR, &sl->flags);
1062                         }
1063                 }
1064         }
1065 }
1066 #endif /* CONFIG_SLIP_MODE_SLIP6 */
1067
1068 /* Perform I/O control on an active SLIP channel. */
1069 static int slip_ioctl(struct tty_struct *tty, struct file *file,
1070                                         unsigned int cmd, unsigned long arg)
1071 {
1072         struct slip *sl = tty->disc_data;
1073         unsigned int tmp;
1074         int __user *p = (int __user *)arg;
1075
1076         /* First make sure we're connected. */
1077         if (!sl || sl->magic != SLIP_MAGIC)
1078                 return -EINVAL;
1079
1080         switch (cmd) {
1081         case SIOCGIFNAME:
1082                 tmp = strlen(sl->dev->name) + 1;
1083                 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
1084                         return -EFAULT;
1085                 return 0;
1086
1087         case SIOCGIFENCAP:
1088                 if (put_user(sl->mode, p))
1089                         return -EFAULT;
1090                 return 0;
1091
1092         case SIOCSIFENCAP:
1093                 if (get_user(tmp, p))
1094                         return -EFAULT;
1095 #ifndef SL_INCLUDE_CSLIP
1096                 if (tmp & (SL_MODE_CSLIP|SL_MODE_ADAPTIVE))
1097                         return -EINVAL;
1098 #else
1099                 if ((tmp & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) ==
1100                     (SL_MODE_ADAPTIVE | SL_MODE_CSLIP))
1101                         /* return -EINVAL; */
1102                         tmp &= ~SL_MODE_ADAPTIVE;
1103 #endif
1104 #ifndef CONFIG_SLIP_MODE_SLIP6
1105                 if (tmp & SL_MODE_SLIP6)
1106                         return -EINVAL;
1107 #endif
1108                 sl->mode = tmp;
1109                 sl->dev->type = ARPHRD_SLIP + sl->mode;
1110                 return 0;
1111
1112         case SIOCSIFHWADDR:
1113                 return -EINVAL;
1114
1115 #ifdef CONFIG_SLIP_SMART
1116         /* VSV changes start here */
1117         case SIOCSKEEPALIVE:
1118                 if (get_user(tmp, p))
1119                         return -EFAULT;
1120                 if (tmp > 255) /* max for unchar */
1121                         return -EINVAL;
1122
1123                 spin_lock_bh(&sl->lock);
1124                 if (!sl->tty) {
1125                         spin_unlock_bh(&sl->lock);
1126                         return -ENODEV;
1127                 }
1128                 sl->keepalive = (u8)tmp;
1129                 if (sl->keepalive != 0) {
1130                         mod_timer(&sl->keepalive_timer,
1131                                         jiffies + sl->keepalive * HZ);
1132                         set_bit(SLF_KEEPTEST, &sl->flags);
1133                 } else
1134                         del_timer(&sl->keepalive_timer);
1135                 spin_unlock_bh(&sl->lock);
1136                 return 0;
1137
1138         case SIOCGKEEPALIVE:
1139                 if (put_user(sl->keepalive, p))
1140                         return -EFAULT;
1141                 return 0;
1142
1143         case SIOCSOUTFILL:
1144                 if (get_user(tmp, p))
1145                         return -EFAULT;
1146                 if (tmp > 255) /* max for unchar */
1147                         return -EINVAL;
1148                 spin_lock_bh(&sl->lock);
1149                 if (!sl->tty) {
1150                         spin_unlock_bh(&sl->lock);
1151                         return -ENODEV;
1152                 }
1153                 sl->outfill = (u8)tmp;
1154                 if (sl->outfill != 0) {
1155                         mod_timer(&sl->outfill_timer,
1156                                                 jiffies + sl->outfill * HZ);
1157                         set_bit(SLF_OUTWAIT, &sl->flags);
1158                 } else
1159                         del_timer(&sl->outfill_timer);
1160                 spin_unlock_bh(&sl->lock);
1161                 return 0;
1162
1163         case SIOCGOUTFILL:
1164                 if (put_user(sl->outfill, p))
1165                         return -EFAULT;
1166                 return 0;
1167         /* VSV changes end */
1168 #endif
1169         default:
1170                 return tty_mode_ioctl(tty, file, cmd, arg);
1171         }
1172 }
1173
1174 #ifdef CONFIG_COMPAT
1175 static long slip_compat_ioctl(struct tty_struct *tty, struct file *file,
1176                                         unsigned int cmd, unsigned long arg)
1177 {
1178         switch (cmd) {
1179         case SIOCGIFNAME:
1180         case SIOCGIFENCAP:
1181         case SIOCSIFENCAP:
1182         case SIOCSIFHWADDR:
1183         case SIOCSKEEPALIVE:
1184         case SIOCGKEEPALIVE:
1185         case SIOCSOUTFILL:
1186         case SIOCGOUTFILL:
1187                 return slip_ioctl(tty, file, cmd,
1188                                   (unsigned long)compat_ptr(arg));
1189         }
1190
1191         return -ENOIOCTLCMD;
1192 }
1193 #endif
1194
1195 /* VSV changes start here */
1196 #ifdef CONFIG_SLIP_SMART
1197 /* function do_ioctl called from net/core/dev.c
1198    to allow get/set outfill/keepalive parameter
1199    by ifconfig                                 */
1200
1201 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
1202 {
1203         struct slip *sl = netdev_priv(dev);
1204         unsigned long *p = (unsigned long *)&rq->ifr_ifru;
1205
1206         if (sl == NULL)         /* Allocation failed ?? */
1207                 return -ENODEV;
1208
1209         spin_lock_bh(&sl->lock);
1210
1211         if (!sl->tty) {
1212                 spin_unlock_bh(&sl->lock);
1213                 return -ENODEV;
1214         }
1215
1216         switch (cmd) {
1217         case SIOCSKEEPALIVE:
1218                 /* max for unchar */
1219                 if ((unsigned)*p > 255) {
1220                         spin_unlock_bh(&sl->lock);
1221                         return -EINVAL;
1222                 }
1223                 sl->keepalive = (u8)*p;
1224                 if (sl->keepalive != 0) {
1225                         sl->keepalive_timer.expires =
1226                                                 jiffies + sl->keepalive * HZ;
1227                         mod_timer(&sl->keepalive_timer,
1228                                                 jiffies + sl->keepalive * HZ);
1229                         set_bit(SLF_KEEPTEST, &sl->flags);
1230                 } else
1231                         del_timer(&sl->keepalive_timer);
1232                 break;
1233
1234         case SIOCGKEEPALIVE:
1235                 *p = sl->keepalive;
1236                 break;
1237
1238         case SIOCSOUTFILL:
1239                 if ((unsigned)*p > 255) { /* max for unchar */
1240                         spin_unlock_bh(&sl->lock);
1241                         return -EINVAL;
1242                 }
1243                 sl->outfill = (u8)*p;
1244                 if (sl->outfill != 0) {
1245                         mod_timer(&sl->outfill_timer,
1246                                                 jiffies + sl->outfill * HZ);
1247                         set_bit(SLF_OUTWAIT, &sl->flags);
1248                 } else
1249                         del_timer(&sl->outfill_timer);
1250                 break;
1251
1252         case SIOCGOUTFILL:
1253                 *p = sl->outfill;
1254                 break;
1255
1256         case SIOCSLEASE:
1257                 /* Resolve race condition, when ioctl'ing hanged up
1258                    and opened by another process device.
1259                  */
1260                 if (sl->tty != current->signal->tty &&
1261                                                 sl->pid != current->pid) {
1262                         spin_unlock_bh(&sl->lock);
1263                         return -EPERM;
1264                 }
1265                 sl->leased = 0;
1266                 if (*p)
1267                         sl->leased = 1;
1268                 break;
1269
1270         case SIOCGLEASE:
1271                 *p = sl->leased;
1272         }
1273         spin_unlock_bh(&sl->lock);
1274         return 0;
1275 }
1276 #endif
1277 /* VSV changes end */
1278
1279 static struct tty_ldisc_ops sl_ldisc = {
1280         .owner          = THIS_MODULE,
1281         .magic          = TTY_LDISC_MAGIC,
1282         .name           = "slip",
1283         .open           = slip_open,
1284         .close          = slip_close,
1285         .hangup         = slip_hangup,
1286         .ioctl          = slip_ioctl,
1287 #ifdef CONFIG_COMPAT
1288         .compat_ioctl   = slip_compat_ioctl,
1289 #endif
1290         .receive_buf    = slip_receive_buf,
1291         .write_wakeup   = slip_write_wakeup,
1292 };
1293
1294 static int __init slip_init(void)
1295 {
1296         int status;
1297
1298         if (slip_maxdev < 4)
1299                 slip_maxdev = 4; /* Sanity */
1300
1301         printk(KERN_INFO "SLIP: version %s (dynamic channels, max=%d)"
1302 #ifdef CONFIG_SLIP_MODE_SLIP6
1303                " (6 bit encapsulation enabled)"
1304 #endif
1305                ".\n",
1306                SLIP_VERSION, slip_maxdev);
1307 #if defined(SL_INCLUDE_CSLIP)
1308         printk(KERN_INFO "CSLIP: code copyright 1989 Regents of the University of California.\n");
1309 #endif
1310 #ifdef CONFIG_SLIP_SMART
1311         printk(KERN_INFO "SLIP linefill/keepalive option.\n");
1312 #endif
1313
1314         slip_devs = kzalloc(sizeof(struct net_device *)*slip_maxdev,
1315                                                                 GFP_KERNEL);
1316         if (!slip_devs) {
1317                 printk(KERN_ERR "SLIP: Can't allocate slip devices array.\n");
1318                 return -ENOMEM;
1319         }
1320
1321         /* Fill in our line protocol discipline, and register it */
1322         status = tty_register_ldisc(N_SLIP, &sl_ldisc);
1323         if (status != 0) {
1324                 printk(KERN_ERR "SLIP: can't register line discipline (err = %d)\n", status);
1325                 kfree(slip_devs);
1326         }
1327         return status;
1328 }
1329
1330 static void __exit slip_exit(void)
1331 {
1332         int i;
1333         struct net_device *dev;
1334         struct slip *sl;
1335         unsigned long timeout = jiffies + HZ;
1336         int busy = 0;
1337
1338         if (slip_devs == NULL)
1339                 return;
1340
1341         /* First of all: check for active disciplines and hangup them.
1342          */
1343         do {
1344                 if (busy)
1345                         msleep_interruptible(100);
1346
1347                 busy = 0;
1348                 for (i = 0; i < slip_maxdev; i++) {
1349                         dev = slip_devs[i];
1350                         if (!dev)
1351                                 continue;
1352                         sl = netdev_priv(dev);
1353                         spin_lock_bh(&sl->lock);
1354                         if (sl->tty) {
1355                                 busy++;
1356                                 tty_hangup(sl->tty);
1357                         }
1358                         spin_unlock_bh(&sl->lock);
1359                 }
1360         } while (busy && time_before(jiffies, timeout));
1361
1362         /* FIXME: hangup is async so we should wait when doing this second
1363            phase */
1364
1365         for (i = 0; i < slip_maxdev; i++) {
1366                 dev = slip_devs[i];
1367                 if (!dev)
1368                         continue;
1369                 slip_devs[i] = NULL;
1370
1371                 sl = netdev_priv(dev);
1372                 if (sl->tty) {
1373                         printk(KERN_ERR "%s: tty discipline still running\n",
1374                                dev->name);
1375                         /* Intentionally leak the control block. */
1376                         dev->destructor = NULL;
1377                 }
1378
1379                 unregister_netdev(dev);
1380         }
1381
1382         kfree(slip_devs);
1383         slip_devs = NULL;
1384
1385         i = tty_unregister_ldisc(N_SLIP);
1386         if (i != 0)
1387                 printk(KERN_ERR "SLIP: can't unregister line discipline (err = %d)\n", i);
1388 }
1389
1390 module_init(slip_init);
1391 module_exit(slip_exit);
1392
1393 #ifdef CONFIG_SLIP_SMART
1394 /*
1395  * This is start of the code for multislip style line checking
1396  * added by Stanislav Voronyi. All changes before marked VSV
1397  */
1398
1399 static void sl_outfill(unsigned long sls)
1400 {
1401         struct slip *sl = (struct slip *)sls;
1402
1403         spin_lock(&sl->lock);
1404
1405         if (sl->tty == NULL)
1406                 goto out;
1407
1408         if (sl->outfill) {
1409                 if (test_bit(SLF_OUTWAIT, &sl->flags)) {
1410                         /* no packets were transmitted, do outfill */
1411 #ifdef CONFIG_SLIP_MODE_SLIP6
1412                         unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END;
1413 #else
1414                         unsigned char s = END;
1415 #endif
1416                         /* put END into tty queue. Is it right ??? */
1417                         if (!netif_queue_stopped(sl->dev)) {
1418                                 /* if device busy no outfill */
1419                                 sl->tty->ops->write(sl->tty, &s, 1);
1420                         }
1421                 } else
1422                         set_bit(SLF_OUTWAIT, &sl->flags);
1423
1424                 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
1425         }
1426 out:
1427         spin_unlock(&sl->lock);
1428 }
1429
1430 static void sl_keepalive(unsigned long sls)
1431 {
1432         struct slip *sl = (struct slip *)sls;
1433
1434         spin_lock(&sl->lock);
1435
1436         if (sl->tty == NULL)
1437                 goto out;
1438
1439         if (sl->keepalive) {
1440                 if (test_bit(SLF_KEEPTEST, &sl->flags)) {
1441                         /* keepalive still high :(, we must hangup */
1442                         if (sl->outfill)
1443                                 /* outfill timer must be deleted too */
1444                                 (void)del_timer(&sl->outfill_timer);
1445                         printk(KERN_DEBUG "%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name);
1446                         /* this must hangup tty & close slip */
1447                         tty_hangup(sl->tty);
1448                         /* I think we need not something else */
1449                         goto out;
1450                 } else
1451                         set_bit(SLF_KEEPTEST, &sl->flags);
1452
1453                 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
1454         }
1455 out:
1456         spin_unlock(&sl->lock);
1457 }
1458
1459 #endif
1460 MODULE_LICENSE("GPL");
1461 MODULE_ALIAS_LDISC(N_SLIP);