drivers/net/slip/slip.c

   1 /*
   2  * slip.c       This module implements the SLIP protocol for kernel-based
   3  *              devices like TTY.  It interfaces between a raw TTY, and the
   4  *              kernel's INET protocol layers.
   5  *
   6  * Version:     @(#)slip.c      0.8.3   12/24/94
   7  *
   8  * Authors:     Laurence Culhane, <[email protected]>
   9  *              Fred N. van Kempen, <[email protected]>
  10  *
  11  * Fixes:
  12  *              Alan Cox        :       Sanity checks and avoid tx overruns.
  13  *                                      Has a new sl->mtu field.
  14  *              Alan Cox        :       Found cause of overrun. ifconfig sl0
  15  *                                      mtu upwards. Driver now spots this
  16  *                                      and grows/shrinks its buffers(hack!).
  17  *                                      Memory leak if you run out of memory
  18  *                                      setting up a slip driver fixed.
  19  *              Matt Dillon     :       Printable slip (borrowed from NET2E)
  20  *      Pauline Middelink       :       Slip driver fixes.
  21  *              Alan Cox        :       Honours the old SL_COMPRESSED flag
  22  *              Alan Cox        :       KISS AX.25 and AXUI IP support
  23  *              Michael Riepe   :       Automatic CSLIP recognition added
  24  *              Charles Hedrick :       CSLIP header length problem fix.
  25  *              Alan Cox        :       Corrected non-IP cases of the above.
  26  *              Alan Cox        :       Now uses hardware type as per FvK.
  27  *              Alan Cox        :       Default to 192.168.0.0 (RFC 1597)
  28  *              A.N.Kuznetsov   :       dev_tint() recursion fix.
  29  *      Dmitry Gorodchanin      :       SLIP memory leaks
  30  *      Dmitry Gorodchanin      :       Code cleanup. Reduce tty driver
  31  *                                      buffering from 4096 to 256 bytes.
  32  *                                      Improving SLIP response time.
  33  *                                      CONFIG_SLIP_MODE_SLIP6.
  34  *                                      ifconfig sl? up & down now works
  35  *                                      correctly.
  36  *                                      Modularization.
  37  *              Alan Cox        :       Oops - fix AX.25 buffer lengths
  38  *      Dmitry Gorodchanin      :       Even more cleanups. Preserve CSLIP
  39  *                                      statistics. Include CSLIP code only
  40  *                                      if it really needed.
  41  *              Alan Cox        :       Free slhc buffers in the right place.
  42  *              Alan Cox        :       Allow for digipeated IP over AX.25
  43  *              Matti Aarnio    :       Dynamic SLIP devices, with ideas taken
  44  *                                      from Jim Freeman's <[email protected]>
  45  *                                      dynamic PPP devices.  We do NOT kfree()
  46  *                                      device entries, just reg./unreg. them
  47  *                                      as they are needed.  We kfree() them
  48  *                                      at module cleanup.
  49  *                                      With MODULE-loading ``insmod'', user
  50  *                                      can issue parameter:  slip_maxdev=1024
  51  *                                      (Or how much he/she wants.. Default
  52  *                                      is 256)
  53  *      Stanislav Voronyi       :       Slip line checking, with ideas taken
  54  *                                      from multislip BSDI driver which was
  55  *                                      written by Igor Chechik, RELCOM Corp.
  56  *                                      Only algorithms have been ported to
  57  *                                      Linux SLIP driver.
  58  *      Vitaly E. Lavrov        :       Sane behaviour on tty hangup.
  59  *      Alexey Kuznetsov        :       Cleanup interfaces to tty & netdevice
  60  *                                      modules.
  61  */
  62
  63 #define SL_CHECK_TRANSMIT
  64 #include <linux/module.h>
  65 #include <linux/moduleparam.h>
  66
  67 #include <asm/system.h>
  68 #include <asm/uaccess.h>
  69 #include <linux/bitops.h>
  70 #include <linux/sched.h>
  71 #include <linux/string.h>
  72 #include <linux/mm.h>
  73 #include <linux/interrupt.h>
  74 #include <linux/in.h>
  75 #include <linux/tty.h>
  76 #include <linux/errno.h>
  77 #include <linux/netdevice.h>
  78 #include <linux/etherdevice.h>
  79 #include <linux/skbuff.h>
  80 #include <linux/rtnetlink.h>
  81 #include <linux/if_arp.h>
  82 #include <linux/if_slip.h>
  83 #include <linux/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 #endif
 186 #ifdef CONFIG_SLIP_MODE_SLIP6
 187         sl->xdata    = 0;
 188         sl->xbits    = 0;
 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         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                         dev->stats.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                         dev->stats.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 net_device *dev = sl->dev;
 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", 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                                 dev->stats.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", 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         dev->stats.rx_bytes += count;
 359
 360         skb = dev_alloc_skb(count);
 361         if (skb == NULL) {
 362                 printk(KERN_WARNING "%s: memory squeeze, dropping packet.\n", dev->name);
 363                 dev->stats.rx_dropped++;
 364                 return;
 365         }
 366         skb->dev = 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_ni(skb);
 371         dev->stats.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->dev->stats.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->dev->stats.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         dev->stats.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 rtnl_link_stats64 *
 562 sl_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
 563 {
 564         struct net_device_stats *devstats = &dev->stats;
 565 #ifdef SL_INCLUDE_CSLIP
 566         struct slip *sl = netdev_priv(dev);
 567         struct slcompress *comp = sl->slcomp;
 568 #endif
 569         stats->rx_packets     = devstats->rx_packets;
 570         stats->tx_packets     = devstats->tx_packets;
 571         stats->rx_bytes       = devstats->rx_bytes;
 572         stats->tx_bytes       = devstats->tx_bytes;
 573         stats->rx_dropped     = devstats->rx_dropped;
 574         stats->tx_dropped     = devstats->tx_dropped;
 575         stats->tx_errors      = devstats->tx_errors;
 576         stats->rx_errors      = devstats->rx_errors;
 577         stats->rx_over_errors = devstats->rx_over_errors;
 578
 579 #ifdef SL_INCLUDE_CSLIP
 580         if (comp) {
 581                 /* Generic compressed statistics */
 582                 stats->rx_compressed   = comp->sls_i_compressed;
 583                 stats->tx_compressed   = comp->sls_o_compressed;
 584
 585                 /* Are we really still needs this? */
 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
 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_stats64        = sl_get_stats64,
 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->dev->stats.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         char name[IFNAMSIZ];
 726         struct net_device *dev = NULL;
 727         struct slip       *sl;
 728
 729         for (i = 0; i < slip_maxdev; i++) {
 730                 dev = slip_devs[i];
 731                 if (dev == NULL)
 732                         break;
 733         }
 734         /* Sorry, too many, all slots in use */
 735         if (i >= slip_maxdev)
 736                 return NULL;
 737
 738         sprintf(name, "sl%d", i);
 739         dev = alloc_netdev(sizeof(*sl), name, sl_setup);
 740         if (!dev)
 741                 return NULL;
 742
 743         dev->base_addr  = i;
 744         sl = netdev_priv(dev);
 745
 746         /* Initialize channel control data */
 747         sl->magic       = SLIP_MAGIC;
 748         sl->dev         = dev;
 749         spin_lock_init(&sl->lock);
 750         sl->mode        = SL_MODE_DEFAULT;
 751 #ifdef CONFIG_SLIP_SMART
 752         /* initialize timer_list struct */
 753         init_timer(&sl->keepalive_timer);
 754         sl->keepalive_timer.data = (unsigned long)sl;
 755         sl->keepalive_timer.function = sl_keepalive;
 756         init_timer(&sl->outfill_timer);
 757         sl->outfill_timer.data = (unsigned long)sl;
 758         sl->outfill_timer.function = sl_outfill;
 759 #endif
 760         slip_devs[i] = dev;
 761         return sl;
 762 }
 763
 764 /*
 765  * Open the high-level part of the SLIP channel.
 766  * This function is called by the TTY module when the
 767  * SLIP line discipline is called for.  Because we are
 768  * sure the tty line exists, we only have to link it to
 769  * a free SLIP channel...
 770  *
 771  * Called in process context serialized from other ldisc calls.
 772  */
 773
 774 static int slip_open(struct tty_struct *tty)
 775 {
 776         struct slip *sl;
 777         int err;
 778
 779         if (!capable(CAP_NET_ADMIN))
 780                 return -EPERM;
 781
 782         if (tty->ops->write == NULL)
 783                 return -EOPNOTSUPP;
 784
 785         /* RTnetlink lock is misused here to serialize concurrent
 786            opens of slip channels. There are better ways, but it is
 787            the simplest one.
 788          */
 789         rtnl_lock();
 790
 791         /* Collect hanged up channels. */
 792         sl_sync();
 793
 794         sl = tty->disc_data;
 795
 796         err = -EEXIST;
 797         /* First make sure we're not already connected. */
 798         if (sl && sl->magic == SLIP_MAGIC)
 799                 goto err_exit;
 800
 801         /* OK.  Find a free SLIP channel to use. */
 802         err = -ENFILE;
 803         sl = sl_alloc(tty_devnum(tty));
 804         if (sl == NULL)
 805                 goto err_exit;
 806
 807         sl->tty = tty;
 808         tty->disc_data = sl;
 809         sl->pid = current->pid;
 810
 811         if (!test_bit(SLF_INUSE, &sl->flags)) {
 812                 /* Perform the low-level SLIP initialization. */
 813                 err = sl_alloc_bufs(sl, SL_MTU);
 814                 if (err)
 815                         goto err_free_chan;
 816
 817                 set_bit(SLF_INUSE, &sl->flags);
 818
 819                 err = register_netdevice(sl->dev);
 820                 if (err)
 821                         goto err_free_bufs;
 822         }
 823
 824 #ifdef CONFIG_SLIP_SMART
 825         if (sl->keepalive) {
 826                 sl->keepalive_timer.expires = jiffies + sl->keepalive * HZ;
 827                 add_timer(&sl->keepalive_timer);
 828         }
 829         if (sl->outfill) {
 830                 sl->outfill_timer.expires = jiffies + sl->outfill * HZ;
 831                 add_timer(&sl->outfill_timer);
 832         }
 833 #endif
 834
 835         /* Done.  We have linked the TTY line to a channel. */
 836         rtnl_unlock();
 837         tty->receive_room = 65536;      /* We don't flow control */
 838
 839         /* TTY layer expects 0 on success */
 840         return 0;
 841
 842 err_free_bufs:
 843         sl_free_bufs(sl);
 844
 845 err_free_chan:
 846         sl->tty = NULL;
 847         tty->disc_data = NULL;
 848         clear_bit(SLF_INUSE, &sl->flags);
 849
 850 err_exit:
 851         rtnl_unlock();
 852
 853         /* Count references from TTY module */
 854         return err;
 855 }
 856
 857 /*
 858  * Close down a SLIP channel.
 859  * This means flushing out any pending queues, and then returning. This
 860  * call is serialized against other ldisc functions.
 861  *
 862  * We also use this method fo a hangup event
 863  */
 864
 865 static void slip_close(struct tty_struct *tty)
 866 {
 867         struct slip *sl = tty->disc_data;
 868
 869         /* First make sure we're connected. */
 870         if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty)
 871                 return;
 872
 873         tty->disc_data = NULL;
 874         sl->tty = NULL;
 875
 876         /* VSV = very important to remove timers */
 877 #ifdef CONFIG_SLIP_SMART
 878         del_timer_sync(&sl->keepalive_timer);
 879         del_timer_sync(&sl->outfill_timer);
 880 #endif
 881         /* Flush network side */
 882         unregister_netdev(sl->dev);
 883         /* This will complete via sl_free_netdev */
 884 }
 885
 886 static int slip_hangup(struct tty_struct *tty)
 887 {
 888         slip_close(tty);
 889         return 0;
 890 }
 891  /************************************************************************
 892   *                     STANDARD SLIP ENCAPSULATION                      *
 893   ************************************************************************/
 894
 895 static int slip_esc(unsigned char *s, unsigned char *d, int len)
 896 {
 897         unsigned char *ptr = d;
 898         unsigned char c;
 899
 900         /*
 901          * Send an initial END character to flush out any
 902          * data that may have accumulated in the receiver
 903          * due to line noise.
 904          */
 905
 906         *ptr++ = END;
 907
 908         /*
 909          * For each byte in the packet, send the appropriate
 910          * character sequence, according to the SLIP protocol.
 911          */
 912
 913         while (len-- > 0) {
 914                 switch (c = *s++) {
 915                 case END:
 916                         *ptr++ = ESC;
 917                         *ptr++ = ESC_END;
 918                         break;
 919                 case ESC:
 920                         *ptr++ = ESC;
 921                         *ptr++ = ESC_ESC;
 922                         break;
 923                 default:
 924                         *ptr++ = c;
 925                         break;
 926                 }
 927         }
 928         *ptr++ = END;
 929         return ptr - d;
 930 }
 931
 932 static void slip_unesc(struct slip *sl, unsigned char s)
 933 {
 934
 935         switch (s) {
 936         case END:
 937 #ifdef CONFIG_SLIP_SMART
 938                 /* drop keeptest bit = VSV */
 939                 if (test_bit(SLF_KEEPTEST, &sl->flags))
 940                         clear_bit(SLF_KEEPTEST, &sl->flags);
 941 #endif
 942
 943                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
 944                     (sl->rcount > 2))
 945                         sl_bump(sl);
 946                 clear_bit(SLF_ESCAPE, &sl->flags);
 947                 sl->rcount = 0;
 948                 return;
 949
 950         case ESC:
 951                 set_bit(SLF_ESCAPE, &sl->flags);
 952                 return;
 953         case ESC_ESC:
 954                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 955                         s = ESC;
 956                 break;
 957         case ESC_END:
 958                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 959                         s = END;
 960                 break;
 961         }
 962         if (!test_bit(SLF_ERROR, &sl->flags))  {
 963                 if (sl->rcount < sl->buffsize)  {
 964                         sl->rbuff[sl->rcount++] = s;
 965                         return;
 966                 }
 967                 sl->dev->stats.rx_over_errors++;
 968                 set_bit(SLF_ERROR, &sl->flags);
 969         }
 970 }
 971
 972
 973 #ifdef CONFIG_SLIP_MODE_SLIP6
 974 /************************************************************************
 975  *                       6 BIT SLIP ENCAPSULATION                       *
 976  ************************************************************************/
 977
 978 static int slip_esc6(unsigned char *s, unsigned char *d, int len)
 979 {
 980         unsigned char *ptr = d;
 981         unsigned char c;
 982         int i;
 983         unsigned short v = 0;
 984         short bits = 0;
 985
 986         /*
 987          * Send an initial END character to flush out any
 988          * data that may have accumulated in the receiver
 989          * due to line noise.
 990          */
 991
 992         *ptr++ = 0x70;
 993
 994         /*
 995          * Encode the packet into printable ascii characters
 996          */
 997
 998         for (i = 0; i < len; ++i) {
 999                 v = (v << 8) | s[i];
1000                 bits += 8;
1001                 while (bits >= 6) {
1002                         bits -= 6;
1003                         c = 0x30 + ((v >> bits) & 0x3F);
1004                         *ptr++ = c;
1005                 }
1006         }
1007         if (bits) {
1008                 c = 0x30 + ((v << (6 - bits)) & 0x3F);
1009                 *ptr++ = c;
1010         }
1011         *ptr++ = 0x70;
1012         return ptr - d;
1013 }
1014
1015 static void slip_unesc6(struct slip *sl, unsigned char s)
1016 {
1017         unsigned char c;
1018
1019         if (s == 0x70) {
1020 #ifdef CONFIG_SLIP_SMART
1021                 /* drop keeptest bit = VSV */
1022                 if (test_bit(SLF_KEEPTEST, &sl->flags))
1023                         clear_bit(SLF_KEEPTEST, &sl->flags);
1024 #endif
1025
1026                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
1027                     (sl->rcount > 2))
1028                         sl_bump(sl);
1029                 sl->rcount = 0;
1030                 sl->xbits = 0;
1031                 sl->xdata = 0;
1032         } else if (s >= 0x30 && s < 0x70) {
1033                 sl->xdata = (sl->xdata << 6) | ((s - 0x30) & 0x3F);
1034                 sl->xbits += 6;
1035                 if (sl->xbits >= 8) {
1036                         sl->xbits -= 8;
1037                         c = (unsigned char)(sl->xdata >> sl->xbits);
1038                         if (!test_bit(SLF_ERROR, &sl->flags))  {
1039                                 if (sl->rcount < sl->buffsize)  {
1040                                         sl->rbuff[sl->rcount++] = c;
1041                                         return;
1042                                 }
1043                                 sl->dev->stats.rx_over_errors++;
1044                                 set_bit(SLF_ERROR, &sl->flags);
1045                         }
1046                 }
1047         }
1048 }
1049 #endif /* CONFIG_SLIP_MODE_SLIP6 */
1050
1051 /* Perform I/O control on an active SLIP channel. */
1052 static int slip_ioctl(struct tty_struct *tty, struct file *file,
1053                                         unsigned int cmd, unsigned long arg)
1054 {
1055         struct slip *sl = tty->disc_data;
1056         unsigned int tmp;
1057         int __user *p = (int __user *)arg;
1058
1059         /* First make sure we're connected. */
1060         if (!sl || sl->magic != SLIP_MAGIC)
1061                 return -EINVAL;
1062
1063         switch (cmd) {
1064         case SIOCGIFNAME:
1065                 tmp = strlen(sl->dev->name) + 1;
1066                 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
1067                         return -EFAULT;
1068                 return 0;
1069
1070         case SIOCGIFENCAP:
1071                 if (put_user(sl->mode, p))
1072                         return -EFAULT;
1073                 return 0;
1074
1075         case SIOCSIFENCAP:
1076                 if (get_user(tmp, p))
1077                         return -EFAULT;
1078 #ifndef SL_INCLUDE_CSLIP
1079                 if (tmp & (SL_MODE_CSLIP|SL_MODE_ADAPTIVE))
1080                         return -EINVAL;
1081 #else
1082                 if ((tmp & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) ==
1083                     (SL_MODE_ADAPTIVE | SL_MODE_CSLIP))
1084                         /* return -EINVAL; */
1085                         tmp &= ~SL_MODE_ADAPTIVE;
1086 #endif
1087 #ifndef CONFIG_SLIP_MODE_SLIP6
1088                 if (tmp & SL_MODE_SLIP6)
1089                         return -EINVAL;
1090 #endif
1091                 sl->mode = tmp;
1092                 sl->dev->type = ARPHRD_SLIP + sl->mode;
1093                 return 0;
1094
1095         case SIOCSIFHWADDR:
1096                 return -EINVAL;
1097
1098 #ifdef CONFIG_SLIP_SMART
1099         /* VSV changes start here */
1100         case SIOCSKEEPALIVE:
1101                 if (get_user(tmp, p))
1102                         return -EFAULT;
1103                 if (tmp > 255) /* max for unchar */
1104                         return -EINVAL;
1105
1106                 spin_lock_bh(&sl->lock);
1107                 if (!sl->tty) {
1108                         spin_unlock_bh(&sl->lock);
1109                         return -ENODEV;
1110                 }
1111                 sl->keepalive = (u8)tmp;
1112                 if (sl->keepalive != 0) {
1113                         mod_timer(&sl->keepalive_timer,
1114                                         jiffies + sl->keepalive * HZ);
1115                         set_bit(SLF_KEEPTEST, &sl->flags);
1116                 } else
1117                         del_timer(&sl->keepalive_timer);
1118                 spin_unlock_bh(&sl->lock);
1119                 return 0;
1120
1121         case SIOCGKEEPALIVE:
1122                 if (put_user(sl->keepalive, p))
1123                         return -EFAULT;
1124                 return 0;
1125
1126         case SIOCSOUTFILL:
1127                 if (get_user(tmp, p))
1128                         return -EFAULT;
1129                 if (tmp > 255) /* max for unchar */
1130                         return -EINVAL;
1131                 spin_lock_bh(&sl->lock);
1132                 if (!sl->tty) {
1133                         spin_unlock_bh(&sl->lock);
1134                         return -ENODEV;
1135                 }
1136                 sl->outfill = (u8)tmp;
1137                 if (sl->outfill != 0) {
1138                         mod_timer(&sl->outfill_timer,
1139                                                 jiffies + sl->outfill * HZ);
1140                         set_bit(SLF_OUTWAIT, &sl->flags);
1141                 } else
1142                         del_timer(&sl->outfill_timer);
1143                 spin_unlock_bh(&sl->lock);
1144                 return 0;
1145
1146         case SIOCGOUTFILL:
1147                 if (put_user(sl->outfill, p))
1148                         return -EFAULT;
1149                 return 0;
1150         /* VSV changes end */
1151 #endif
1152         default:
1153                 return tty_mode_ioctl(tty, file, cmd, arg);
1154         }
1155 }
1156
1157 #ifdef CONFIG_COMPAT
1158 static long slip_compat_ioctl(struct tty_struct *tty, struct file *file,
1159                                         unsigned int cmd, unsigned long arg)
1160 {
1161         switch (cmd) {
1162         case SIOCGIFNAME:
1163         case SIOCGIFENCAP:
1164         case SIOCSIFENCAP:
1165         case SIOCSIFHWADDR:
1166         case SIOCSKEEPALIVE:
1167         case SIOCGKEEPALIVE:
1168         case SIOCSOUTFILL:
1169         case SIOCGOUTFILL:
1170                 return slip_ioctl(tty, file, cmd,
1171                                   (unsigned long)compat_ptr(arg));
1172         }
1173
1174         return -ENOIOCTLCMD;
1175 }
1176 #endif
1177
1178 /* VSV changes start here */
1179 #ifdef CONFIG_SLIP_SMART
1180 /* function do_ioctl called from net/core/dev.c
1181    to allow get/set outfill/keepalive parameter
1182    by ifconfig                                 */
1183
1184 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
1185 {
1186         struct slip *sl = netdev_priv(dev);
1187         unsigned long *p = (unsigned long *)&rq->ifr_ifru;
1188
1189         if (sl == NULL)         /* Allocation failed ?? */
1190                 return -ENODEV;
1191
1192         spin_lock_bh(&sl->lock);
1193
1194         if (!sl->tty) {
1195                 spin_unlock_bh(&sl->lock);
1196                 return -ENODEV;
1197         }
1198
1199         switch (cmd) {
1200         case SIOCSKEEPALIVE:
1201                 /* max for unchar */
1202                 if ((unsigned)*p > 255) {
1203                         spin_unlock_bh(&sl->lock);
1204                         return -EINVAL;
1205                 }
1206                 sl->keepalive = (u8)*p;
1207                 if (sl->keepalive != 0) {
1208                         sl->keepalive_timer.expires =
1209                                                 jiffies + sl->keepalive * HZ;
1210                         mod_timer(&sl->keepalive_timer,
1211                                                 jiffies + sl->keepalive * HZ);
1212                         set_bit(SLF_KEEPTEST, &sl->flags);
1213                 } else
1214                         del_timer(&sl->keepalive_timer);
1215                 break;
1216
1217         case SIOCGKEEPALIVE:
1218                 *p = sl->keepalive;
1219                 break;
1220
1221         case SIOCSOUTFILL:
1222                 if ((unsigned)*p > 255) { /* max for unchar */
1223                         spin_unlock_bh(&sl->lock);
1224                         return -EINVAL;
1225                 }
1226                 sl->outfill = (u8)*p;
1227                 if (sl->outfill != 0) {
1228                         mod_timer(&sl->outfill_timer,
1229                                                 jiffies + sl->outfill * HZ);
1230                         set_bit(SLF_OUTWAIT, &sl->flags);
1231                 } else
1232                         del_timer(&sl->outfill_timer);
1233                 break;
1234
1235         case SIOCGOUTFILL:
1236                 *p = sl->outfill;
1237                 break;
1238
1239         case SIOCSLEASE:
1240                 /* Resolve race condition, when ioctl'ing hanged up
1241                    and opened by another process device.
1242                  */
1243                 if (sl->tty != current->signal->tty &&
1244                                                 sl->pid != current->pid) {
1245                         spin_unlock_bh(&sl->lock);
1246                         return -EPERM;
1247                 }
1248                 sl->leased = 0;
1249                 if (*p)
1250                         sl->leased = 1;
1251                 break;
1252
1253         case SIOCGLEASE:
1254                 *p = sl->leased;
1255         }
1256         spin_unlock_bh(&sl->lock);
1257         return 0;
1258 }
1259 #endif
1260 /* VSV changes end */
1261
1262 static struct tty_ldisc_ops sl_ldisc = {
1263         .owner          = THIS_MODULE,
1264         .magic          = TTY_LDISC_MAGIC,
1265         .name           = "slip",
1266         .open           = slip_open,
1267         .close          = slip_close,
1268         .hangup         = slip_hangup,
1269         .ioctl          = slip_ioctl,
1270 #ifdef CONFIG_COMPAT
1271         .compat_ioctl   = slip_compat_ioctl,
1272 #endif
1273         .receive_buf    = slip_receive_buf,
1274         .write_wakeup   = slip_write_wakeup,
1275 };
1276
1277 static int __init slip_init(void)
1278 {
1279         int status;
1280
1281         if (slip_maxdev < 4)
1282                 slip_maxdev = 4; /* Sanity */
1283
1284         printk(KERN_INFO "SLIP: version %s (dynamic channels, max=%d)"
1285 #ifdef CONFIG_SLIP_MODE_SLIP6
1286                " (6 bit encapsulation enabled)"
1287 #endif
1288                ".\n",
1289                SLIP_VERSION, slip_maxdev);
1290 #if defined(SL_INCLUDE_CSLIP)
1291         printk(KERN_INFO "CSLIP: code copyright 1989 Regents of the University of California.\n");
1292 #endif
1293 #ifdef CONFIG_SLIP_SMART
1294         printk(KERN_INFO "SLIP linefill/keepalive option.\n");
1295 #endif
1296
1297         slip_devs = kzalloc(sizeof(struct net_device *)*slip_maxdev,
1298                                                                 GFP_KERNEL);
1299         if (!slip_devs) {
1300                 printk(KERN_ERR "SLIP: Can't allocate slip devices array.\n");
1301                 return -ENOMEM;
1302         }
1303
1304         /* Fill in our line protocol discipline, and register it */
1305         status = tty_register_ldisc(N_SLIP, &sl_ldisc);
1306         if (status != 0) {
1307                 printk(KERN_ERR "SLIP: can't register line discipline (err = %d)\n", status);
1308                 kfree(slip_devs);
1309         }
1310         return status;
1311 }
1312
1313 static void __exit slip_exit(void)
1314 {
1315         int i;
1316         struct net_device *dev;
1317         struct slip *sl;
1318         unsigned long timeout = jiffies + HZ;
1319         int busy = 0;
1320
1321         if (slip_devs == NULL)
1322                 return;
1323
1324         /* First of all: check for active disciplines and hangup them.
1325          */
1326         do {
1327                 if (busy)
1328                         msleep_interruptible(100);
1329
1330                 busy = 0;
1331                 for (i = 0; i < slip_maxdev; i++) {
1332                         dev = slip_devs[i];
1333                         if (!dev)
1334                                 continue;
1335                         sl = netdev_priv(dev);
1336                         spin_lock_bh(&sl->lock);
1337                         if (sl->tty) {
1338                                 busy++;
1339                                 tty_hangup(sl->tty);
1340                         }
1341                         spin_unlock_bh(&sl->lock);
1342                 }
1343         } while (busy && time_before(jiffies, timeout));
1344
1345         /* FIXME: hangup is async so we should wait when doing this second
1346            phase */
1347
1348         for (i = 0; i < slip_maxdev; i++) {
1349                 dev = slip_devs[i];
1350                 if (!dev)
1351                         continue;
1352                 slip_devs[i] = NULL;
1353
1354                 sl = netdev_priv(dev);
1355                 if (sl->tty) {
1356                         printk(KERN_ERR "%s: tty discipline still running\n",
1357                                dev->name);
1358                         /* Intentionally leak the control block. */
1359                         dev->destructor = NULL;
1360                 }
1361
1362                 unregister_netdev(dev);
1363         }
1364
1365         kfree(slip_devs);
1366         slip_devs = NULL;
1367
1368         i = tty_unregister_ldisc(N_SLIP);
1369         if (i != 0)
1370                 printk(KERN_ERR "SLIP: can't unregister line discipline (err = %d)\n", i);
1371 }
1372
1373 module_init(slip_init);
1374 module_exit(slip_exit);
1375
1376 #ifdef CONFIG_SLIP_SMART
1377 /*
1378  * This is start of the code for multislip style line checking
1379  * added by Stanislav Voronyi. All changes before marked VSV
1380  */
1381
1382 static void sl_outfill(unsigned long sls)
1383 {
1384         struct slip *sl = (struct slip *)sls;
1385
1386         spin_lock(&sl->lock);
1387
1388         if (sl->tty == NULL)
1389                 goto out;
1390
1391         if (sl->outfill) {
1392                 if (test_bit(SLF_OUTWAIT, &sl->flags)) {
1393                         /* no packets were transmitted, do outfill */
1394 #ifdef CONFIG_SLIP_MODE_SLIP6
1395                         unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END;
1396 #else
1397                         unsigned char s = END;
1398 #endif
1399                         /* put END into tty queue. Is it right ??? */
1400                         if (!netif_queue_stopped(sl->dev)) {
1401                                 /* if device busy no outfill */
1402                                 sl->tty->ops->write(sl->tty, &s, 1);
1403                         }
1404                 } else
1405                         set_bit(SLF_OUTWAIT, &sl->flags);
1406
1407                 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
1408         }
1409 out:
1410         spin_unlock(&sl->lock);
1411 }
1412
1413 static void sl_keepalive(unsigned long sls)
1414 {
1415         struct slip *sl = (struct slip *)sls;
1416
1417         spin_lock(&sl->lock);
1418
1419         if (sl->tty == NULL)
1420                 goto out;
1421
1422         if (sl->keepalive) {
1423                 if (test_bit(SLF_KEEPTEST, &sl->flags)) {
1424                         /* keepalive still high :(, we must hangup */
1425                         if (sl->outfill)
1426                                 /* outfill timer must be deleted too */
1427                                 (void)del_timer(&sl->outfill_timer);
1428                         printk(KERN_DEBUG "%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name);
1429                         /* this must hangup tty & close slip */
1430                         tty_hangup(sl->tty);
1431                         /* I think we need not something else */
1432                         goto out;
1433                 } else
1434                         set_bit(SLF_KEEPTEST, &sl->flags);
1435
1436                 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
1437         }
1438 out:
1439         spin_unlock(&sl->lock);
1440 }
1441
1442 #endif
1443 MODULE_LICENSE("GPL");
1444 MODULE_ALIAS_LDISC(N_SLIP);