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