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 <linux/slab.h>
  87 #include "slip.h"
  88 #ifdef CONFIG_INET
  89 #include <linux/ip.h>
  90 #include <linux/tcp.h>
  91 #include <net/slhc_vj.h>
  92 #endif
  93
  94 #define SLIP_VERSION    "0.8.4-NET3.019-NEWTTY"
  95
  96 static struct net_device **slip_devs;
  97
  98 static int slip_maxdev = SL_NRUNIT;
  99 module_param(slip_maxdev, int, 0);
 100 MODULE_PARM_DESC(slip_maxdev, "Maximum number of slip devices");
 101
 102 static int slip_esc(unsigned char *p, unsigned char *d, int len);
 103 static void slip_unesc(struct slip *sl, unsigned char c);
 104 #ifdef CONFIG_SLIP_MODE_SLIP6
 105 static int slip_esc6(unsigned char *p, unsigned char *d, int len);
 106 static void slip_unesc6(struct slip *sl, unsigned char c);
 107 #endif
 108 #ifdef CONFIG_SLIP_SMART
 109 static void sl_keepalive(unsigned long sls);
 110 static void sl_outfill(unsigned long sls);
 111 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
 112 #endif
 113
 114 /********************************
 115 *  Buffer administration routines:
 116 *       sl_alloc_bufs()
 117 *       sl_free_bufs()
 118 *       sl_realloc_bufs()
 119 *
 120 * NOTE: sl_realloc_bufs != sl_free_bufs + sl_alloc_bufs, because
 121 *       sl_realloc_bufs provides strong atomicity and reallocation
 122 *       on actively running device.
 123 *********************************/
 124
 125 /*
 126    Allocate channel buffers.
 127  */
 128
 129 static int sl_alloc_bufs(struct slip *sl, int mtu)
 130 {
 131         int err = -ENOBUFS;
 132         unsigned long len;
 133         char *rbuff = NULL;
 134         char *xbuff = NULL;
 135 #ifdef SL_INCLUDE_CSLIP
 136         char *cbuff = NULL;
 137         struct slcompress *slcomp = NULL;
 138 #endif
 139
 140         /*
 141          * Allocate the SLIP frame buffers:
 142          *
 143          * rbuff        Receive buffer.
 144          * xbuff        Transmit buffer.
 145          * cbuff        Temporary compression buffer.
 146          */
 147         len = mtu * 2;
 148
 149         /*
 150          * allow for arrival of larger UDP packets, even if we say not to
 151          * also fixes a bug in which SunOS sends 512-byte packets even with
 152          * an MSS of 128
 153          */
 154         if (len < 576 * 2)
 155                 len = 576 * 2;
 156         rbuff = kmalloc(len + 4, GFP_KERNEL);
 157         if (rbuff == NULL)
 158                 goto err_exit;
 159         xbuff = kmalloc(len + 4, GFP_KERNEL);
 160         if (xbuff == NULL)
 161                 goto err_exit;
 162 #ifdef SL_INCLUDE_CSLIP
 163         cbuff = kmalloc(len + 4, GFP_KERNEL);
 164         if (cbuff == NULL)
 165                 goto err_exit;
 166         slcomp = slhc_init(16, 16);
 167         if (slcomp == NULL)
 168                 goto err_exit;
 169 #endif
 170         spin_lock_bh(&sl->lock);
 171         if (sl->tty == NULL) {
 172                 spin_unlock_bh(&sl->lock);
 173                 err = -ENODEV;
 174                 goto err_exit;
 175         }
 176         sl->mtu      = mtu;
 177         sl->buffsize = len;
 178         sl->rcount   = 0;
 179         sl->xleft    = 0;
 180         rbuff = xchg(&sl->rbuff, rbuff);
 181         xbuff = xchg(&sl->xbuff, xbuff);
 182 #ifdef SL_INCLUDE_CSLIP
 183         cbuff = xchg(&sl->cbuff, cbuff);
 184         slcomp = xchg(&sl->slcomp, slcomp);
 185 #ifdef CONFIG_SLIP_MODE_SLIP6
 186         sl->xdata    = 0;
 187         sl->xbits    = 0;
 188 #endif
 189 #endif
 190         spin_unlock_bh(&sl->lock);
 191         err = 0;
 192
 193         /* Cleanup */
 194 err_exit:
 195 #ifdef SL_INCLUDE_CSLIP
 196         kfree(cbuff);
 197         if (slcomp)
 198                 slhc_free(slcomp);
 199 #endif
 200         kfree(xbuff);
 201         kfree(rbuff);
 202         return err;
 203 }
 204
 205 /* Free a SLIP channel buffers. */
 206 static void sl_free_bufs(struct slip *sl)
 207 {
 208         /* Free all SLIP frame buffers. */
 209         kfree(xchg(&sl->rbuff, NULL));
 210         kfree(xchg(&sl->xbuff, NULL));
 211 #ifdef SL_INCLUDE_CSLIP
 212         kfree(xchg(&sl->cbuff, NULL));
 213         slhc_free(xchg(&sl->slcomp, NULL));
 214 #endif
 215 }
 216
 217 /*
 218    Reallocate slip channel buffers.
 219  */
 220
 221 static int sl_realloc_bufs(struct slip *sl, int mtu)
 222 {
 223         int err = 0;
 224         struct net_device *dev = sl->dev;
 225         unsigned char *xbuff, *rbuff;
 226 #ifdef SL_INCLUDE_CSLIP
 227         unsigned char *cbuff;
 228 #endif
 229         int len = mtu * 2;
 230
 231 /*
 232  * allow for arrival of larger UDP packets, even if we say not to
 233  * also fixes a bug in which SunOS sends 512-byte packets even with
 234  * an MSS of 128
 235  */
 236         if (len < 576 * 2)
 237                 len = 576 * 2;
 238
 239         xbuff = kmalloc(len + 4, GFP_ATOMIC);
 240         rbuff = kmalloc(len + 4, GFP_ATOMIC);
 241 #ifdef SL_INCLUDE_CSLIP
 242         cbuff = kmalloc(len + 4, GFP_ATOMIC);
 243 #endif
 244
 245
 246 #ifdef SL_INCLUDE_CSLIP
 247         if (xbuff == NULL || rbuff == NULL || cbuff == NULL)  {
 248 #else
 249         if (xbuff == NULL || rbuff == NULL)  {
 250 #endif
 251                 if (mtu >= sl->mtu) {
 252                         printk(KERN_WARNING "%s: unable to grow slip buffers, MTU change cancelled.\n",
 253                                dev->name);
 254                         err = -ENOBUFS;
 255                 }
 256                 goto done;
 257         }
 258         spin_lock_bh(&sl->lock);
 259
 260         err = -ENODEV;
 261         if (sl->tty == NULL)
 262                 goto done_on_bh;
 263
 264         xbuff    = xchg(&sl->xbuff, xbuff);
 265         rbuff    = xchg(&sl->rbuff, rbuff);
 266 #ifdef SL_INCLUDE_CSLIP
 267         cbuff    = xchg(&sl->cbuff, cbuff);
 268 #endif
 269         if (sl->xleft)  {
 270                 if (sl->xleft <= len)  {
 271                         memcpy(sl->xbuff, sl->xhead, sl->xleft);
 272                 } else  {
 273                         sl->xleft = 0;
 274                         dev->stats.tx_dropped++;
 275                 }
 276         }
 277         sl->xhead = sl->xbuff;
 278
 279         if (sl->rcount)  {
 280                 if (sl->rcount <= len) {
 281                         memcpy(sl->rbuff, rbuff, sl->rcount);
 282                 } else  {
 283                         sl->rcount = 0;
 284                         dev->stats.rx_over_errors++;
 285                         set_bit(SLF_ERROR, &sl->flags);
 286                 }
 287         }
 288         sl->mtu      = mtu;
 289         dev->mtu      = mtu;
 290         sl->buffsize = len;
 291         err = 0;
 292
 293 done_on_bh:
 294         spin_unlock_bh(&sl->lock);
 295
 296 done:
 297         kfree(xbuff);
 298         kfree(rbuff);
 299 #ifdef SL_INCLUDE_CSLIP
 300         kfree(cbuff);
 301 #endif
 302         return err;
 303 }
 304
 305
 306 /* Set the "sending" flag.  This must be atomic hence the set_bit. */
 307 static inline void sl_lock(struct slip *sl)
 308 {
 309         netif_stop_queue(sl->dev);
 310 }
 311
 312
 313 /* Clear the "sending" flag.  This must be atomic, hence the ASM. */
 314 static inline void sl_unlock(struct slip *sl)
 315 {
 316         netif_wake_queue(sl->dev);
 317 }
 318
 319 /* Send one completely decapsulated IP datagram to the IP layer. */
 320 static void sl_bump(struct slip *sl)
 321 {
 322         struct net_device *dev = sl->dev;
 323         struct sk_buff *skb;
 324         int count;
 325
 326         count = sl->rcount;
 327 #ifdef SL_INCLUDE_CSLIP
 328         if (sl->mode & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) {
 329                 unsigned char c = sl->rbuff[0];
 330                 if (c & SL_TYPE_COMPRESSED_TCP) {
 331                         /* ignore compressed packets when CSLIP is off */
 332                         if (!(sl->mode & SL_MODE_CSLIP)) {
 333                                 printk(KERN_WARNING "%s: compressed packet ignored\n", dev->name);
 334                                 return;
 335                         }
 336                         /* make sure we've reserved enough space for uncompress
 337                            to use */
 338                         if (count + 80 > sl->buffsize) {
 339                                 dev->stats.rx_over_errors++;
 340                                 return;
 341                         }
 342                         count = slhc_uncompress(sl->slcomp, sl->rbuff, count);
 343                         if (count <= 0)
 344                                 return;
 345                 } else if (c >= SL_TYPE_UNCOMPRESSED_TCP) {
 346                         if (!(sl->mode & SL_MODE_CSLIP)) {
 347                                 /* turn on header compression */
 348                                 sl->mode |= SL_MODE_CSLIP;
 349                                 sl->mode &= ~SL_MODE_ADAPTIVE;
 350                                 printk(KERN_INFO "%s: header compression turned on\n", dev->name);
 351                         }
 352                         sl->rbuff[0] &= 0x4f;
 353                         if (slhc_remember(sl->slcomp, sl->rbuff, count) <= 0)
 354                                 return;
 355                 }
 356         }
 357 #endif  /* SL_INCLUDE_CSLIP */
 358
 359         dev->stats.rx_bytes += count;
 360
 361         skb = dev_alloc_skb(count);
 362         if (skb == NULL) {
 363                 printk(KERN_WARNING "%s: memory squeeze, dropping packet.\n", dev->name);
 364                 dev->stats.rx_dropped++;
 365                 return;
 366         }
 367         skb->dev = dev;
 368         memcpy(skb_put(skb, count), sl->rbuff, count);
 369         skb_reset_mac_header(skb);
 370         skb->protocol = htons(ETH_P_IP);
 371         netif_rx(skb);
 372         dev->stats.rx_packets++;
 373 }
 374
 375 /* Encapsulate one IP datagram and stuff into a TTY queue. */
 376 static void sl_encaps(struct slip *sl, unsigned char *icp, int len)
 377 {
 378         unsigned char *p;
 379         int actual, count;
 380
 381         if (len > sl->mtu) {            /* Sigh, shouldn't occur BUT ... */
 382                 printk(KERN_WARNING "%s: truncating oversized transmit packet!\n", sl->dev->name);
 383                 sl->dev->stats.tx_dropped++;
 384                 sl_unlock(sl);
 385                 return;
 386         }
 387
 388         p = icp;
 389 #ifdef SL_INCLUDE_CSLIP
 390         if (sl->mode & SL_MODE_CSLIP)
 391                 len = slhc_compress(sl->slcomp, p, len, sl->cbuff, &p, 1);
 392 #endif
 393 #ifdef CONFIG_SLIP_MODE_SLIP6
 394         if (sl->mode & SL_MODE_SLIP6)
 395                 count = slip_esc6(p, (unsigned char *) sl->xbuff, len);
 396         else
 397 #endif
 398                 count = slip_esc(p, (unsigned char *) sl->xbuff, len);
 399
 400         /* Order of next two lines is *very* important.
 401          * When we are sending a little amount of data,
 402          * the transfer may be completed inside the ops->write()
 403          * routine, because it's running with interrupts enabled.
 404          * In this case we *never* got WRITE_WAKEUP event,
 405          * if we did not request it before write operation.
 406          *       14 Oct 1994  Dmitry Gorodchanin.
 407          */
 408         set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 409         actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
 410 #ifdef SL_CHECK_TRANSMIT
 411         sl->dev->trans_start = jiffies;
 412 #endif
 413         sl->xleft = count - actual;
 414         sl->xhead = sl->xbuff + actual;
 415 #ifdef CONFIG_SLIP_SMART
 416         /* VSV */
 417         clear_bit(SLF_OUTWAIT, &sl->flags);     /* reset outfill flag */
 418 #endif
 419 }
 420
 421 /*
 422  * Called by the driver when there's room for more data.  If we have
 423  * more packets to send, we send them here.
 424  */
 425 static void slip_write_wakeup(struct tty_struct *tty)
 426 {
 427         int actual;
 428         struct slip *sl = tty->disc_data;
 429
 430         /* First make sure we're connected. */
 431         if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
 432                 return;
 433
 434         if (sl->xleft <= 0)  {
 435                 /* Now serial buffer is almost free & we can start
 436                  * transmission of another packet */
 437                 sl->dev->stats.tx_packets++;
 438                 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 439                 sl_unlock(sl);
 440                 return;
 441         }
 442
 443         actual = tty->ops->write(tty, sl->xhead, sl->xleft);
 444         sl->xleft -= actual;
 445         sl->xhead += actual;
 446 }
 447
 448 static void sl_tx_timeout(struct net_device *dev)
 449 {
 450         struct slip *sl = netdev_priv(dev);
 451
 452         spin_lock(&sl->lock);
 453
 454         if (netif_queue_stopped(dev)) {
 455                 if (!netif_running(dev))
 456                         goto out;
 457
 458                 /* May be we must check transmitter timeout here ?
 459                  *      14 Oct 1994 Dmitry Gorodchanin.
 460                  */
 461 #ifdef SL_CHECK_TRANSMIT
 462                 if (time_before(jiffies, dev_trans_start(dev) + 20 * HZ))  {
 463                         /* 20 sec timeout not reached */
 464                         goto out;
 465                 }
 466                 printk(KERN_WARNING "%s: transmit timed out, %s?\n",
 467                         dev->name,
 468                         (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
 469                                 "bad line quality" : "driver error");
 470                 sl->xleft = 0;
 471                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 472                 sl_unlock(sl);
 473 #endif
 474         }
 475 out:
 476         spin_unlock(&sl->lock);
 477 }
 478
 479
 480 /* Encapsulate an IP datagram and kick it into a TTY queue. */
 481 static netdev_tx_t
 482 sl_xmit(struct sk_buff *skb, struct net_device *dev)
 483 {
 484         struct slip *sl = netdev_priv(dev);
 485
 486         spin_lock(&sl->lock);
 487         if (!netif_running(dev)) {
 488                 spin_unlock(&sl->lock);
 489                 printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name);
 490                 dev_kfree_skb(skb);
 491                 return NETDEV_TX_OK;
 492         }
 493         if (sl->tty == NULL) {
 494                 spin_unlock(&sl->lock);
 495                 dev_kfree_skb(skb);
 496                 return NETDEV_TX_OK;
 497         }
 498
 499         sl_lock(sl);
 500         dev->stats.tx_bytes += skb->len;
 501         sl_encaps(sl, skb->data, skb->len);
 502         spin_unlock(&sl->lock);
 503
 504         dev_kfree_skb(skb);
 505         return NETDEV_TX_OK;
 506 }
 507
 508
 509 /******************************************
 510  *   Routines looking at netdevice side.
 511  ******************************************/
 512
 513 /* Netdevice UP -> DOWN routine */
 514
 515 static int
 516 sl_close(struct net_device *dev)
 517 {
 518         struct slip *sl = netdev_priv(dev);
 519
 520         spin_lock_bh(&sl->lock);
 521         if (sl->tty)
 522                 /* TTY discipline is running. */
 523                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 524         netif_stop_queue(dev);
 525         sl->rcount   = 0;
 526         sl->xleft    = 0;
 527         spin_unlock_bh(&sl->lock);
 528
 529         return 0;
 530 }
 531
 532 /* Netdevice DOWN -> UP routine */
 533
 534 static int sl_open(struct net_device *dev)
 535 {
 536         struct slip *sl = netdev_priv(dev);
 537
 538         if (sl->tty == NULL)
 539                 return -ENODEV;
 540
 541         sl->flags &= (1 << SLF_INUSE);
 542         netif_start_queue(dev);
 543         return 0;
 544 }
 545
 546 /* Netdevice change MTU request */
 547
 548 static int sl_change_mtu(struct net_device *dev, int new_mtu)
 549 {
 550         struct slip *sl = netdev_priv(dev);
 551
 552         if (new_mtu < 68 || new_mtu > 65534)
 553                 return -EINVAL;
 554
 555         if (new_mtu != dev->mtu)
 556                 return sl_realloc_bufs(sl, new_mtu);
 557         return 0;
 558 }
 559
 560 /* Netdevice get statistics request */
 561
 562 static struct rtnl_link_stats64 *
 563 sl_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
 564 {
 565         struct net_device_stats *devstats = &dev->stats;
 566         unsigned long c_rx_dropped = 0;
 567 #ifdef SL_INCLUDE_CSLIP
 568         unsigned long c_rx_fifo_errors = 0;
 569         unsigned long c_tx_fifo_errors = 0;
 570         unsigned long c_collisions = 0;
 571         struct slip *sl = netdev_priv(dev);
 572         struct slcompress *comp = sl->slcomp;
 573
 574         if (comp) {
 575                 c_rx_fifo_errors = comp->sls_i_compressed;
 576                 c_rx_dropped     = comp->sls_i_tossed;
 577                 c_tx_fifo_errors = comp->sls_o_compressed;
 578                 c_collisions     = comp->sls_o_misses;
 579         }
 580         stats->rx_fifo_errors = sl->rx_compressed + c_rx_fifo_errors;
 581         stats->tx_fifo_errors = sl->tx_compressed + c_tx_fifo_errors;
 582         stats->collisions     = sl->tx_misses + c_collisions;
 583 #endif
 584         stats->rx_packets     = devstats->rx_packets;
 585         stats->tx_packets     = devstats->tx_packets;
 586         stats->rx_bytes       = devstats->rx_bytes;
 587         stats->tx_bytes       = devstats->tx_bytes;
 588         stats->rx_dropped     = devstats->rx_dropped + c_rx_dropped;
 589         stats->tx_dropped     = devstats->tx_dropped;
 590         stats->tx_errors      = devstats->tx_errors;
 591         stats->rx_errors      = devstats->rx_errors;
 592         stats->rx_over_errors = devstats->rx_over_errors;
 593
 594         return stats;
 595 }
 596
 597 /* Netdevice register callback */
 598
 599 static int sl_init(struct net_device *dev)
 600 {
 601         struct slip *sl = netdev_priv(dev);
 602
 603         /*
 604          *      Finish setting up the DEVICE info.
 605          */
 606
 607         dev->mtu                = sl->mtu;
 608         dev->type               = ARPHRD_SLIP + sl->mode;
 609 #ifdef SL_CHECK_TRANSMIT
 610         dev->watchdog_timeo     = 20*HZ;
 611 #endif
 612         return 0;
 613 }
 614
 615
 616 static void sl_uninit(struct net_device *dev)
 617 {
 618         struct slip *sl = netdev_priv(dev);
 619
 620         sl_free_bufs(sl);
 621 }
 622
 623 /* Hook the destructor so we can free slip devices at the right point in time */
 624 static void sl_free_netdev(struct net_device *dev)
 625 {
 626         int i = dev->base_addr;
 627         free_netdev(dev);
 628         slip_devs[i] = NULL;
 629 }
 630
 631 static const struct net_device_ops sl_netdev_ops = {
 632         .ndo_init               = sl_init,
 633         .ndo_uninit             = sl_uninit,
 634         .ndo_open               = sl_open,
 635         .ndo_stop               = sl_close,
 636         .ndo_start_xmit         = sl_xmit,
 637         .ndo_get_stats64        = sl_get_stats64,
 638         .ndo_change_mtu         = sl_change_mtu,
 639         .ndo_tx_timeout         = sl_tx_timeout,
 640 #ifdef CONFIG_SLIP_SMART
 641         .ndo_do_ioctl           = sl_ioctl,
 642 #endif
 643 };
 644
 645
 646 static void sl_setup(struct net_device *dev)
 647 {
 648         dev->netdev_ops         = &sl_netdev_ops;
 649         dev->destructor         = sl_free_netdev;
 650
 651         dev->hard_header_len    = 0;
 652         dev->addr_len           = 0;
 653         dev->tx_queue_len       = 10;
 654
 655         /* New-style flags. */
 656         dev->flags              = IFF_NOARP|IFF_POINTOPOINT|IFF_MULTICAST;
 657 }
 658
 659 /******************************************
 660   Routines looking at TTY side.
 661  ******************************************/
 662
 663
 664 /*
 665  * Handle the 'receiver data ready' interrupt.
 666  * This function is called by the 'tty_io' module in the kernel when
 667  * a block of SLIP data has been received, which can now be decapsulated
 668  * and sent on to some IP layer for further processing. This will not
 669  * be re-entered while running but other ldisc functions may be called
 670  * in parallel
 671  */
 672
 673 static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 674                                                         char *fp, int count)
 675 {
 676         struct slip *sl = tty->disc_data;
 677
 678         if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
 679                 return;
 680
 681         /* Read the characters out of the buffer */
 682         while (count--) {
 683                 if (fp && *fp++) {
 684                         if (!test_and_set_bit(SLF_ERROR, &sl->flags))
 685                                 sl->dev->stats.rx_errors++;
 686                         cp++;
 687                         continue;
 688                 }
 689 #ifdef CONFIG_SLIP_MODE_SLIP6
 690                 if (sl->mode & SL_MODE_SLIP6)
 691                         slip_unesc6(sl, *cp++);
 692                 else
 693 #endif
 694                         slip_unesc(sl, *cp++);
 695         }
 696 }
 697
 698 /************************************
 699  *  slip_open helper routines.
 700  ************************************/
 701
 702 /* Collect hanged up channels */
 703 static void sl_sync(void)
 704 {
 705         int i;
 706         struct net_device *dev;
 707         struct slip       *sl;
 708
 709         for (i = 0; i < slip_maxdev; i++) {
 710                 dev = slip_devs[i];
 711                 if (dev == NULL)
 712                         break;
 713
 714                 sl = netdev_priv(dev);
 715                 if (sl->tty || sl->leased)
 716                         continue;
 717                 if (dev->flags & IFF_UP)
 718                         dev_close(dev);
 719         }
 720 }
 721
 722
 723 /* Find a free SLIP channel, and link in this `tty' line. */
 724 static struct slip *sl_alloc(dev_t line)
 725 {
 726         int i;
 727         struct net_device *dev = NULL;
 728         struct slip       *sl;
 729
 730         if (slip_devs == NULL)
 731                 return NULL;    /* Master array missing ! */
 732
 733         for (i = 0; i < slip_maxdev; i++) {
 734                 dev = slip_devs[i];
 735                 if (dev == NULL)
 736                         break;
 737         }
 738         /* Sorry, too many, all slots in use */
 739         if (i >= slip_maxdev)
 740                 return NULL;
 741
 742         if (dev) {
 743                 sl = netdev_priv(dev);
 744                 if (test_bit(SLF_INUSE, &sl->flags)) {
 745                         unregister_netdevice(dev);
 746                         dev = NULL;
 747                         slip_devs[i] = NULL;
 748                 }
 749         }
 750
 751         if (!dev) {
 752                 char name[IFNAMSIZ];
 753                 sprintf(name, "sl%d", i);
 754
 755                 dev = alloc_netdev(sizeof(*sl), name, sl_setup);
 756                 if (!dev)
 757                         return NULL;
 758                 dev->base_addr  = i;
 759         }
 760
 761         sl = netdev_priv(dev);
 762
 763         /* Initialize channel control data */
 764         sl->magic       = SLIP_MAGIC;
 765         sl->dev         = dev;
 766         spin_lock_init(&sl->lock);
 767         sl->mode        = SL_MODE_DEFAULT;
 768 #ifdef CONFIG_SLIP_SMART
 769         /* initialize timer_list struct */
 770         init_timer(&sl->keepalive_timer);
 771         sl->keepalive_timer.data = (unsigned long)sl;
 772         sl->keepalive_timer.function = sl_keepalive;
 773         init_timer(&sl->outfill_timer);
 774         sl->outfill_timer.data = (unsigned long)sl;
 775         sl->outfill_timer.function = sl_outfill;
 776 #endif
 777         slip_devs[i] = dev;
 778         return sl;
 779 }
 780
 781 /*
 782  * Open the high-level part of the SLIP channel.
 783  * This function is called by the TTY module when the
 784  * SLIP line discipline is called for.  Because we are
 785  * sure the tty line exists, we only have to link it to
 786  * a free SLIP channel...
 787  *
 788  * Called in process context serialized from other ldisc calls.
 789  */
 790
 791 static int slip_open(struct tty_struct *tty)
 792 {
 793         struct slip *sl;
 794         int err;
 795
 796         if (!capable(CAP_NET_ADMIN))
 797                 return -EPERM;
 798
 799         if (tty->ops->write == NULL)
 800                 return -EOPNOTSUPP;
 801
 802         /* RTnetlink lock is misused here to serialize concurrent
 803            opens of slip channels. There are better ways, but it is
 804            the simplest one.
 805          */
 806         rtnl_lock();
 807
 808         /* Collect hanged up channels. */
 809         sl_sync();
 810
 811         sl = tty->disc_data;
 812
 813         err = -EEXIST;
 814         /* First make sure we're not already connected. */
 815         if (sl && sl->magic == SLIP_MAGIC)
 816                 goto err_exit;
 817
 818         /* OK.  Find a free SLIP channel to use. */
 819         err = -ENFILE;
 820         sl = sl_alloc(tty_devnum(tty));
 821         if (sl == NULL)
 822                 goto err_exit;
 823
 824         sl->tty = tty;
 825         tty->disc_data = sl;
 826         sl->line = tty_devnum(tty);
 827         sl->pid = current->pid;
 828
 829         if (!test_bit(SLF_INUSE, &sl->flags)) {
 830                 /* Perform the low-level SLIP initialization. */
 831                 err = sl_alloc_bufs(sl, SL_MTU);
 832                 if (err)
 833                         goto err_free_chan;
 834
 835                 set_bit(SLF_INUSE, &sl->flags);
 836
 837                 err = register_netdevice(sl->dev);
 838                 if (err)
 839                         goto err_free_bufs;
 840         }
 841
 842 #ifdef CONFIG_SLIP_SMART
 843         if (sl->keepalive) {
 844                 sl->keepalive_timer.expires = jiffies + sl->keepalive * HZ;
 845                 add_timer(&sl->keepalive_timer);
 846         }
 847         if (sl->outfill) {
 848                 sl->outfill_timer.expires = jiffies + sl->outfill * HZ;
 849                 add_timer(&sl->outfill_timer);
 850         }
 851 #endif
 852
 853         /* Done.  We have linked the TTY line to a channel. */
 854         rtnl_unlock();
 855         tty->receive_room = 65536;      /* We don't flow control */
 856
 857         /* TTY layer expects 0 on success */
 858         return 0;
 859
 860 err_free_bufs:
 861         sl_free_bufs(sl);
 862
 863 err_free_chan:
 864         sl->tty = NULL;
 865         tty->disc_data = NULL;
 866         clear_bit(SLF_INUSE, &sl->flags);
 867
 868 err_exit:
 869         rtnl_unlock();
 870
 871         /* Count references from TTY module */
 872         return err;
 873 }
 874
 875 /*
 876  * Close down a SLIP channel.
 877  * This means flushing out any pending queues, and then returning. This
 878  * call is serialized against other ldisc functions.
 879  *
 880  * We also use this method fo a hangup event
 881  */
 882
 883 static void slip_close(struct tty_struct *tty)
 884 {
 885         struct slip *sl = tty->disc_data;
 886
 887         /* First make sure we're connected. */
 888         if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty)
 889                 return;
 890
 891         tty->disc_data = NULL;
 892         sl->tty = NULL;
 893         if (!sl->leased)
 894                 sl->line = 0;
 895
 896         /* VSV = very important to remove timers */
 897 #ifdef CONFIG_SLIP_SMART
 898         del_timer_sync(&sl->keepalive_timer);
 899         del_timer_sync(&sl->outfill_timer);
 900 #endif
 901         /* Flush network side */
 902         unregister_netdev(sl->dev);
 903         /* This will complete via sl_free_netdev */
 904 }
 905
 906 static int slip_hangup(struct tty_struct *tty)
 907 {
 908         slip_close(tty);
 909         return 0;
 910 }
 911  /************************************************************************
 912   *                     STANDARD SLIP ENCAPSULATION                      *
 913   ************************************************************************/
 914
 915 static int slip_esc(unsigned char *s, unsigned char *d, int len)
 916 {
 917         unsigned char *ptr = d;
 918         unsigned char c;
 919
 920         /*
 921          * Send an initial END character to flush out any
 922          * data that may have accumulated in the receiver
 923          * due to line noise.
 924          */
 925
 926         *ptr++ = END;
 927
 928         /*
 929          * For each byte in the packet, send the appropriate
 930          * character sequence, according to the SLIP protocol.
 931          */
 932
 933         while (len-- > 0) {
 934                 switch (c = *s++) {
 935                 case END:
 936                         *ptr++ = ESC;
 937                         *ptr++ = ESC_END;
 938                         break;
 939                 case ESC:
 940                         *ptr++ = ESC;
 941                         *ptr++ = ESC_ESC;
 942                         break;
 943                 default:
 944                         *ptr++ = c;
 945                         break;
 946                 }
 947         }
 948         *ptr++ = END;
 949         return ptr - d;
 950 }
 951
 952 static void slip_unesc(struct slip *sl, unsigned char s)
 953 {
 954
 955         switch (s) {
 956         case END:
 957 #ifdef CONFIG_SLIP_SMART
 958                 /* drop keeptest bit = VSV */
 959                 if (test_bit(SLF_KEEPTEST, &sl->flags))
 960                         clear_bit(SLF_KEEPTEST, &sl->flags);
 961 #endif
 962
 963                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
 964                     (sl->rcount > 2))
 965                         sl_bump(sl);
 966                 clear_bit(SLF_ESCAPE, &sl->flags);
 967                 sl->rcount = 0;
 968                 return;
 969
 970         case ESC:
 971                 set_bit(SLF_ESCAPE, &sl->flags);
 972                 return;
 973         case ESC_ESC:
 974                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 975                         s = ESC;
 976                 break;
 977         case ESC_END:
 978                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 979                         s = END;
 980                 break;
 981         }
 982         if (!test_bit(SLF_ERROR, &sl->flags))  {
 983                 if (sl->rcount < sl->buffsize)  {
 984                         sl->rbuff[sl->rcount++] = s;
 985                         return;
 986                 }
 987                 sl->dev->stats.rx_over_errors++;
 988                 set_bit(SLF_ERROR, &sl->flags);
 989         }
 990 }
 991
 992
 993 #ifdef CONFIG_SLIP_MODE_SLIP6
 994 /************************************************************************
 995  *                       6 BIT SLIP ENCAPSULATION                       *
 996  ************************************************************************/
 997
 998 static int slip_esc6(unsigned char *s, unsigned char *d, int len)
 999 {
1000         unsigned char *ptr = d;
1001         unsigned char c;
1002         int i;
1003         unsigned short v = 0;
1004         short bits = 0;
1005
1006         /*
1007          * Send an initial END character to flush out any
1008          * data that may have accumulated in the receiver
1009          * due to line noise.
1010          */
1011
1012         *ptr++ = 0x70;
1013
1014         /*
1015          * Encode the packet into printable ascii characters
1016          */
1017
1018         for (i = 0; i < len; ++i) {
1019                 v = (v << 8) | s[i];
1020                 bits += 8;
1021                 while (bits >= 6) {
1022                         bits -= 6;
1023                         c = 0x30 + ((v >> bits) & 0x3F);
1024                         *ptr++ = c;
1025                 }
1026         }
1027         if (bits) {
1028                 c = 0x30 + ((v << (6 - bits)) & 0x3F);
1029                 *ptr++ = c;
1030         }
1031         *ptr++ = 0x70;
1032         return ptr - d;
1033 }
1034
1035 static void slip_unesc6(struct slip *sl, unsigned char s)
1036 {
1037         unsigned char c;
1038
1039         if (s == 0x70) {
1040 #ifdef CONFIG_SLIP_SMART
1041                 /* drop keeptest bit = VSV */
1042                 if (test_bit(SLF_KEEPTEST, &sl->flags))
1043                         clear_bit(SLF_KEEPTEST, &sl->flags);
1044 #endif
1045
1046                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
1047                     (sl->rcount > 2))
1048                         sl_bump(sl);
1049                 sl->rcount = 0;
1050                 sl->xbits = 0;
1051                 sl->xdata = 0;
1052         } else if (s >= 0x30 && s < 0x70) {
1053                 sl->xdata = (sl->xdata << 6) | ((s - 0x30) & 0x3F);
1054                 sl->xbits += 6;
1055                 if (sl->xbits >= 8) {
1056                         sl->xbits -= 8;
1057                         c = (unsigned char)(sl->xdata >> sl->xbits);
1058                         if (!test_bit(SLF_ERROR, &sl->flags))  {
1059                                 if (sl->rcount < sl->buffsize)  {
1060                                         sl->rbuff[sl->rcount++] = c;
1061                                         return;
1062                                 }
1063                                 sl->dev->stats.rx_over_errors++;
1064                                 set_bit(SLF_ERROR, &sl->flags);
1065                         }
1066                 }
1067         }
1068 }
1069 #endif /* CONFIG_SLIP_MODE_SLIP6 */
1070
1071 /* Perform I/O control on an active SLIP channel. */
1072 static int slip_ioctl(struct tty_struct *tty, struct file *file,
1073                                         unsigned int cmd, unsigned long arg)
1074 {
1075         struct slip *sl = tty->disc_data;
1076         unsigned int tmp;
1077         int __user *p = (int __user *)arg;
1078
1079         /* First make sure we're connected. */
1080         if (!sl || sl->magic != SLIP_MAGIC)
1081                 return -EINVAL;
1082
1083         switch (cmd) {
1084         case SIOCGIFNAME:
1085                 tmp = strlen(sl->dev->name) + 1;
1086                 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
1087                         return -EFAULT;
1088                 return 0;
1089
1090         case SIOCGIFENCAP:
1091                 if (put_user(sl->mode, p))
1092                         return -EFAULT;
1093                 return 0;
1094
1095         case SIOCSIFENCAP:
1096                 if (get_user(tmp, p))
1097                         return -EFAULT;
1098 #ifndef SL_INCLUDE_CSLIP
1099                 if (tmp & (SL_MODE_CSLIP|SL_MODE_ADAPTIVE))
1100                         return -EINVAL;
1101 #else
1102                 if ((tmp & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) ==
1103                     (SL_MODE_ADAPTIVE | SL_MODE_CSLIP))
1104                         /* return -EINVAL; */
1105                         tmp &= ~SL_MODE_ADAPTIVE;
1106 #endif
1107 #ifndef CONFIG_SLIP_MODE_SLIP6
1108                 if (tmp & SL_MODE_SLIP6)
1109                         return -EINVAL;
1110 #endif
1111                 sl->mode = tmp;
1112                 sl->dev->type = ARPHRD_SLIP + sl->mode;
1113                 return 0;
1114
1115         case SIOCSIFHWADDR:
1116                 return -EINVAL;
1117
1118 #ifdef CONFIG_SLIP_SMART
1119         /* VSV changes start here */
1120         case SIOCSKEEPALIVE:
1121                 if (get_user(tmp, p))
1122                         return -EFAULT;
1123                 if (tmp > 255) /* max for unchar */
1124                         return -EINVAL;
1125
1126                 spin_lock_bh(&sl->lock);
1127                 if (!sl->tty) {
1128                         spin_unlock_bh(&sl->lock);
1129                         return -ENODEV;
1130                 }
1131                 sl->keepalive = (u8)tmp;
1132                 if (sl->keepalive != 0) {
1133                         mod_timer(&sl->keepalive_timer,
1134                                         jiffies + sl->keepalive * HZ);
1135                         set_bit(SLF_KEEPTEST, &sl->flags);
1136                 } else
1137                         del_timer(&sl->keepalive_timer);
1138                 spin_unlock_bh(&sl->lock);
1139                 return 0;
1140
1141         case SIOCGKEEPALIVE:
1142                 if (put_user(sl->keepalive, p))
1143                         return -EFAULT;
1144                 return 0;
1145
1146         case SIOCSOUTFILL:
1147                 if (get_user(tmp, p))
1148                         return -EFAULT;
1149                 if (tmp > 255) /* max for unchar */
1150                         return -EINVAL;
1151                 spin_lock_bh(&sl->lock);
1152                 if (!sl->tty) {
1153                         spin_unlock_bh(&sl->lock);
1154                         return -ENODEV;
1155                 }
1156                 sl->outfill = (u8)tmp;
1157                 if (sl->outfill != 0) {
1158                         mod_timer(&sl->outfill_timer,
1159                                                 jiffies + sl->outfill * HZ);
1160                         set_bit(SLF_OUTWAIT, &sl->flags);
1161                 } else
1162                         del_timer(&sl->outfill_timer);
1163                 spin_unlock_bh(&sl->lock);
1164                 return 0;
1165
1166         case SIOCGOUTFILL:
1167                 if (put_user(sl->outfill, p))
1168                         return -EFAULT;
1169                 return 0;
1170         /* VSV changes end */
1171 #endif
1172         default:
1173                 return tty_mode_ioctl(tty, file, cmd, arg);
1174         }
1175 }
1176
1177 #ifdef CONFIG_COMPAT
1178 static long slip_compat_ioctl(struct tty_struct *tty, struct file *file,
1179                                         unsigned int cmd, unsigned long arg)
1180 {
1181         switch (cmd) {
1182         case SIOCGIFNAME:
1183         case SIOCGIFENCAP:
1184         case SIOCSIFENCAP:
1185         case SIOCSIFHWADDR:
1186         case SIOCSKEEPALIVE:
1187         case SIOCGKEEPALIVE:
1188         case SIOCSOUTFILL:
1189         case SIOCGOUTFILL:
1190                 return slip_ioctl(tty, file, cmd,
1191                                   (unsigned long)compat_ptr(arg));
1192         }
1193
1194         return -ENOIOCTLCMD;
1195 }
1196 #endif
1197
1198 /* VSV changes start here */
1199 #ifdef CONFIG_SLIP_SMART
1200 /* function do_ioctl called from net/core/dev.c
1201    to allow get/set outfill/keepalive parameter
1202    by ifconfig                                 */
1203
1204 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
1205 {
1206         struct slip *sl = netdev_priv(dev);
1207         unsigned long *p = (unsigned long *)&rq->ifr_ifru;
1208
1209         if (sl == NULL)         /* Allocation failed ?? */
1210                 return -ENODEV;
1211
1212         spin_lock_bh(&sl->lock);
1213
1214         if (!sl->tty) {
1215                 spin_unlock_bh(&sl->lock);
1216                 return -ENODEV;
1217         }
1218
1219         switch (cmd) {
1220         case SIOCSKEEPALIVE:
1221                 /* max for unchar */
1222                 if ((unsigned)*p > 255) {
1223                         spin_unlock_bh(&sl->lock);
1224                         return -EINVAL;
1225                 }
1226                 sl->keepalive = (u8)*p;
1227                 if (sl->keepalive != 0) {
1228                         sl->keepalive_timer.expires =
1229                                                 jiffies + sl->keepalive * HZ;
1230                         mod_timer(&sl->keepalive_timer,
1231                                                 jiffies + sl->keepalive * HZ);
1232                         set_bit(SLF_KEEPTEST, &sl->flags);
1233                 } else
1234                         del_timer(&sl->keepalive_timer);
1235                 break;
1236
1237         case SIOCGKEEPALIVE:
1238                 *p = sl->keepalive;
1239                 break;
1240
1241         case SIOCSOUTFILL:
1242                 if ((unsigned)*p > 255) { /* max for unchar */
1243                         spin_unlock_bh(&sl->lock);
1244                         return -EINVAL;
1245                 }
1246                 sl->outfill = (u8)*p;
1247                 if (sl->outfill != 0) {
1248                         mod_timer(&sl->outfill_timer,
1249                                                 jiffies + sl->outfill * HZ);
1250                         set_bit(SLF_OUTWAIT, &sl->flags);
1251                 } else
1252                         del_timer(&sl->outfill_timer);
1253                 break;
1254
1255         case SIOCGOUTFILL:
1256                 *p = sl->outfill;
1257                 break;
1258
1259         case SIOCSLEASE:
1260                 /* Resolve race condition, when ioctl'ing hanged up
1261                    and opened by another process device.
1262                  */
1263                 if (sl->tty != current->signal->tty &&
1264                                                 sl->pid != current->pid) {
1265                         spin_unlock_bh(&sl->lock);
1266                         return -EPERM;
1267                 }
1268                 sl->leased = 0;
1269                 if (*p)
1270                         sl->leased = 1;
1271                 break;
1272
1273         case SIOCGLEASE:
1274                 *p = sl->leased;
1275         }
1276         spin_unlock_bh(&sl->lock);
1277         return 0;
1278 }
1279 #endif
1280 /* VSV changes end */
1281
1282 static struct tty_ldisc_ops sl_ldisc = {
1283         .owner          = THIS_MODULE,
1284         .magic          = TTY_LDISC_MAGIC,
1285         .name           = "slip",
1286         .open           = slip_open,
1287         .close          = slip_close,
1288         .hangup         = slip_hangup,
1289         .ioctl          = slip_ioctl,
1290 #ifdef CONFIG_COMPAT
1291         .compat_ioctl   = slip_compat_ioctl,
1292 #endif
1293         .receive_buf    = slip_receive_buf,
1294         .write_wakeup   = slip_write_wakeup,
1295 };
1296
1297 static int __init slip_init(void)
1298 {
1299         int status;
1300
1301         if (slip_maxdev < 4)
1302                 slip_maxdev = 4; /* Sanity */
1303
1304         printk(KERN_INFO "SLIP: version %s (dynamic channels, max=%d)"
1305 #ifdef CONFIG_SLIP_MODE_SLIP6
1306                " (6 bit encapsulation enabled)"
1307 #endif
1308                ".\n",
1309                SLIP_VERSION, slip_maxdev);
1310 #if defined(SL_INCLUDE_CSLIP)
1311         printk(KERN_INFO "CSLIP: code copyright 1989 Regents of the University of California.\n");
1312 #endif
1313 #ifdef CONFIG_SLIP_SMART
1314         printk(KERN_INFO "SLIP linefill/keepalive option.\n");
1315 #endif
1316
1317         slip_devs = kzalloc(sizeof(struct net_device *)*slip_maxdev,
1318                                                                 GFP_KERNEL);
1319         if (!slip_devs) {
1320                 printk(KERN_ERR "SLIP: Can't allocate slip devices array.\n");
1321                 return -ENOMEM;
1322         }
1323
1324         /* Fill in our line protocol discipline, and register it */
1325         status = tty_register_ldisc(N_SLIP, &sl_ldisc);
1326         if (status != 0) {
1327                 printk(KERN_ERR "SLIP: can't register line discipline (err = %d)\n", status);
1328                 kfree(slip_devs);
1329         }
1330         return status;
1331 }
1332
1333 static void __exit slip_exit(void)
1334 {
1335         int i;
1336         struct net_device *dev;
1337         struct slip *sl;
1338         unsigned long timeout = jiffies + HZ;
1339         int busy = 0;
1340
1341         if (slip_devs == NULL)
1342                 return;
1343
1344         /* First of all: check for active disciplines and hangup them.
1345          */
1346         do {
1347                 if (busy)
1348                         msleep_interruptible(100);
1349
1350                 busy = 0;
1351                 for (i = 0; i < slip_maxdev; i++) {
1352                         dev = slip_devs[i];
1353                         if (!dev)
1354                                 continue;
1355                         sl = netdev_priv(dev);
1356                         spin_lock_bh(&sl->lock);
1357                         if (sl->tty) {
1358                                 busy++;
1359                                 tty_hangup(sl->tty);
1360                         }
1361                         spin_unlock_bh(&sl->lock);
1362                 }
1363         } while (busy && time_before(jiffies, timeout));
1364
1365         /* FIXME: hangup is async so we should wait when doing this second
1366            phase */
1367
1368         for (i = 0; i < slip_maxdev; i++) {
1369                 dev = slip_devs[i];
1370                 if (!dev)
1371                         continue;
1372                 slip_devs[i] = NULL;
1373
1374                 sl = netdev_priv(dev);
1375                 if (sl->tty) {
1376                         printk(KERN_ERR "%s: tty discipline still running\n",
1377                                dev->name);
1378                         /* Intentionally leak the control block. */
1379                         dev->destructor = NULL;
1380                 }
1381
1382                 unregister_netdev(dev);
1383         }
1384
1385         kfree(slip_devs);
1386         slip_devs = NULL;
1387
1388         i = tty_unregister_ldisc(N_SLIP);
1389         if (i != 0)
1390                 printk(KERN_ERR "SLIP: can't unregister line discipline (err = %d)\n", i);
1391 }
1392
1393 module_init(slip_init);
1394 module_exit(slip_exit);
1395
1396 #ifdef CONFIG_SLIP_SMART
1397 /*
1398  * This is start of the code for multislip style line checking
1399  * added by Stanislav Voronyi. All changes before marked VSV
1400  */
1401
1402 static void sl_outfill(unsigned long sls)
1403 {
1404         struct slip *sl = (struct slip *)sls;
1405
1406         spin_lock(&sl->lock);
1407
1408         if (sl->tty == NULL)
1409                 goto out;
1410
1411         if (sl->outfill) {
1412                 if (test_bit(SLF_OUTWAIT, &sl->flags)) {
1413                         /* no packets were transmitted, do outfill */
1414 #ifdef CONFIG_SLIP_MODE_SLIP6
1415                         unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END;
1416 #else
1417                         unsigned char s = END;
1418 #endif
1419                         /* put END into tty queue. Is it right ??? */
1420                         if (!netif_queue_stopped(sl->dev)) {
1421                                 /* if device busy no outfill */
1422                                 sl->tty->ops->write(sl->tty, &s, 1);
1423                         }
1424                 } else
1425                         set_bit(SLF_OUTWAIT, &sl->flags);
1426
1427                 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
1428         }
1429 out:
1430         spin_unlock(&sl->lock);
1431 }
1432
1433 static void sl_keepalive(unsigned long sls)
1434 {
1435         struct slip *sl = (struct slip *)sls;
1436
1437         spin_lock(&sl->lock);
1438
1439         if (sl->tty == NULL)
1440                 goto out;
1441
1442         if (sl->keepalive) {
1443                 if (test_bit(SLF_KEEPTEST, &sl->flags)) {
1444                         /* keepalive still high :(, we must hangup */
1445                         if (sl->outfill)
1446                                 /* outfill timer must be deleted too */
1447                                 (void)del_timer(&sl->outfill_timer);
1448                         printk(KERN_DEBUG "%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name);
1449                         /* this must hangup tty & close slip */
1450                         tty_hangup(sl->tty);
1451                         /* I think we need not something else */
1452                         goto out;
1453                 } else
1454                         set_bit(SLF_KEEPTEST, &sl->flags);
1455
1456                 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
1457         }
1458 out:
1459         spin_unlock(&sl->lock);
1460 }
1461
1462 #endif
1463 MODULE_LICENSE("GPL");
1464 MODULE_ALIAS_LDISC(N_SLIP);