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