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, <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/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         spin_lock_bh(&sl->lock);
 433         if (sl->xleft <= 0)  {
 434                 /* Now serial buffer is almost free & we can start
 435                  * transmission of another packet */
 436                 sl->dev->stats.tx_packets++;
 437                 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 438                 spin_unlock_bh(&sl->lock);
 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         spin_unlock_bh(&sl->lock);
 447 }
 448
 449 static void sl_tx_timeout(struct net_device *dev)
 450 {
 451         struct slip *sl = netdev_priv(dev);
 452
 453         spin_lock(&sl->lock);
 454
 455         if (netif_queue_stopped(dev)) {
 456                 if (!netif_running(dev))
 457                         goto out;
 458
 459                 /* May be we must check transmitter timeout here ?
 460                  *      14 Oct 1994 Dmitry Gorodchanin.
 461                  */
 462 #ifdef SL_CHECK_TRANSMIT
 463                 if (time_before(jiffies, dev_trans_start(dev) + 20 * HZ))  {
 464                         /* 20 sec timeout not reached */
 465                         goto out;
 466                 }
 467                 printk(KERN_WARNING "%s: transmit timed out, %s?\n",
 468                         dev->name,
 469                         (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
 470                                 "bad line quality" : "driver error");
 471                 sl->xleft = 0;
 472                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 473                 sl_unlock(sl);
 474 #endif
 475         }
 476 out:
 477         spin_unlock(&sl->lock);
 478 }
 479
 480
 481 /* Encapsulate an IP datagram and kick it into a TTY queue. */
 482 static netdev_tx_t
 483 sl_xmit(struct sk_buff *skb, struct net_device *dev)
 484 {
 485         struct slip *sl = netdev_priv(dev);
 486
 487         spin_lock(&sl->lock);
 488         if (!netif_running(dev)) {
 489                 spin_unlock(&sl->lock);
 490                 printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name);
 491                 dev_kfree_skb(skb);
 492                 return NETDEV_TX_OK;
 493         }
 494         if (sl->tty == NULL) {
 495                 spin_unlock(&sl->lock);
 496                 dev_kfree_skb(skb);
 497                 return NETDEV_TX_OK;
 498         }
 499
 500         sl_lock(sl);
 501         dev->stats.tx_bytes += skb->len;
 502         sl_encaps(sl, skb->data, skb->len);
 503         spin_unlock(&sl->lock);
 504
 505         dev_kfree_skb(skb);
 506         return NETDEV_TX_OK;
 507 }
 508
 509
 510 /******************************************
 511  *   Routines looking at netdevice side.
 512  ******************************************/
 513
 514 /* Netdevice UP -> DOWN routine */
 515
 516 static int
 517 sl_close(struct net_device *dev)
 518 {
 519         struct slip *sl = netdev_priv(dev);
 520
 521         spin_lock_bh(&sl->lock);
 522         if (sl->tty)
 523                 /* TTY discipline is running. */
 524                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 525         netif_stop_queue(dev);
 526         sl->rcount   = 0;
 527         sl->xleft    = 0;
 528         spin_unlock_bh(&sl->lock);
 529
 530         return 0;
 531 }
 532
 533 /* Netdevice DOWN -> UP routine */
 534
 535 static int sl_open(struct net_device *dev)
 536 {
 537         struct slip *sl = netdev_priv(dev);
 538
 539         if (sl->tty == NULL)
 540                 return -ENODEV;
 541
 542         sl->flags &= (1 << SLF_INUSE);
 543         netif_start_queue(dev);
 544         return 0;
 545 }
 546
 547 /* Netdevice change MTU request */
 548
 549 static int sl_change_mtu(struct net_device *dev, int new_mtu)
 550 {
 551         struct slip *sl = netdev_priv(dev);
 552
 553         if (new_mtu < 68 || new_mtu > 65534)
 554                 return -EINVAL;
 555
 556         if (new_mtu != dev->mtu)
 557                 return sl_realloc_bufs(sl, new_mtu);
 558         return 0;
 559 }
 560
 561 /* Netdevice get statistics request */
 562
 563 static struct rtnl_link_stats64 *
 564 sl_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
 565 {
 566         struct net_device_stats *devstats = &dev->stats;
 567 #ifdef SL_INCLUDE_CSLIP
 568         struct slip *sl = netdev_priv(dev);
 569         struct slcompress *comp = sl->slcomp;
 570 #endif
 571         stats->rx_packets     = devstats->rx_packets;
 572         stats->tx_packets     = devstats->tx_packets;
 573         stats->rx_bytes       = devstats->rx_bytes;
 574         stats->tx_bytes       = devstats->tx_bytes;
 575         stats->rx_dropped     = devstats->rx_dropped;
 576         stats->tx_dropped     = devstats->tx_dropped;
 577         stats->tx_errors      = devstats->tx_errors;
 578         stats->rx_errors      = devstats->rx_errors;
 579         stats->rx_over_errors = devstats->rx_over_errors;
 580
 581 #ifdef SL_INCLUDE_CSLIP
 582         if (comp) {
 583                 /* Generic compressed statistics */
 584                 stats->rx_compressed   = comp->sls_i_compressed;
 585                 stats->tx_compressed   = comp->sls_o_compressed;
 586
 587                 /* Are we really still needs this? */
 588                 stats->rx_fifo_errors += comp->sls_i_compressed;
 589                 stats->rx_dropped     += comp->sls_i_tossed;
 590                 stats->tx_fifo_errors += comp->sls_o_compressed;
 591                 stats->collisions     += comp->sls_o_misses;
 592         }
 593 #endif
 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         char name[IFNAMSIZ];
 728         struct net_device *dev = NULL;
 729         struct slip       *sl;
 730
 731         for (i = 0; i < slip_maxdev; i++) {
 732                 dev = slip_devs[i];
 733                 if (dev == NULL)
 734                         break;
 735         }
 736         /* Sorry, too many, all slots in use */
 737         if (i >= slip_maxdev)
 738                 return NULL;
 739
 740         sprintf(name, "sl%d", i);
 741         dev = alloc_netdev(sizeof(*sl), name, sl_setup);
 742         if (!dev)
 743                 return NULL;
 744
 745         dev->base_addr  = i;
 746         sl = netdev_priv(dev);
 747
 748         /* Initialize channel control data */
 749         sl->magic       = SLIP_MAGIC;
 750         sl->dev         = dev;
 751         spin_lock_init(&sl->lock);
 752         sl->mode        = SL_MODE_DEFAULT;
 753 #ifdef CONFIG_SLIP_SMART
 754         /* initialize timer_list struct */
 755         init_timer(&sl->keepalive_timer);
 756         sl->keepalive_timer.data = (unsigned long)sl;
 757         sl->keepalive_timer.function = sl_keepalive;
 758         init_timer(&sl->outfill_timer);
 759         sl->outfill_timer.data = (unsigned long)sl;
 760         sl->outfill_timer.function = sl_outfill;
 761 #endif
 762         slip_devs[i] = dev;
 763         return sl;
 764 }
 765
 766 /*
 767  * Open the high-level part of the SLIP channel.
 768  * This function is called by the TTY module when the
 769  * SLIP line discipline is called for.  Because we are
 770  * sure the tty line exists, we only have to link it to
 771  * a free SLIP channel...
 772  *
 773  * Called in process context serialized from other ldisc calls.
 774  */
 775
 776 static int slip_open(struct tty_struct *tty)
 777 {
 778         struct slip *sl;
 779         int err;
 780
 781         if (!capable(CAP_NET_ADMIN))
 782                 return -EPERM;
 783
 784         if (tty->ops->write == NULL)
 785                 return -EOPNOTSUPP;
 786
 787         /* RTnetlink lock is misused here to serialize concurrent
 788            opens of slip channels. There are better ways, but it is
 789            the simplest one.
 790          */
 791         rtnl_lock();
 792
 793         /* Collect hanged up channels. */
 794         sl_sync();
 795
 796         sl = tty->disc_data;
 797
 798         err = -EEXIST;
 799         /* First make sure we're not already connected. */
 800         if (sl && sl->magic == SLIP_MAGIC)
 801                 goto err_exit;
 802
 803         /* OK.  Find a free SLIP channel to use. */
 804         err = -ENFILE;
 805         sl = sl_alloc(tty_devnum(tty));
 806         if (sl == NULL)
 807                 goto err_exit;
 808
 809         sl->tty = tty;
 810         tty->disc_data = sl;
 811         sl->pid = current->pid;
 812
 813         if (!test_bit(SLF_INUSE, &sl->flags)) {
 814                 /* Perform the low-level SLIP initialization. */
 815                 err = sl_alloc_bufs(sl, SL_MTU);
 816                 if (err)
 817                         goto err_free_chan;
 818
 819                 set_bit(SLF_INUSE, &sl->flags);
 820
 821                 err = register_netdevice(sl->dev);
 822                 if (err)
 823                         goto err_free_bufs;
 824         }
 825
 826 #ifdef CONFIG_SLIP_SMART
 827         if (sl->keepalive) {
 828                 sl->keepalive_timer.expires = jiffies + sl->keepalive * HZ;
 829                 add_timer(&sl->keepalive_timer);
 830         }
 831         if (sl->outfill) {
 832                 sl->outfill_timer.expires = jiffies + sl->outfill * HZ;
 833                 add_timer(&sl->outfill_timer);
 834         }
 835 #endif
 836
 837         /* Done.  We have linked the TTY line to a channel. */
 838         rtnl_unlock();
 839         tty->receive_room = 65536;      /* We don't flow control */
 840
 841         /* TTY layer expects 0 on success */
 842         return 0;
 843
 844 err_free_bufs:
 845         sl_free_bufs(sl);
 846
 847 err_free_chan:
 848         sl->tty = NULL;
 849         tty->disc_data = NULL;
 850         clear_bit(SLF_INUSE, &sl->flags);
 851
 852 err_exit:
 853         rtnl_unlock();
 854
 855         /* Count references from TTY module */
 856         return err;
 857 }
 858
 859 /*
 860  * Close down a SLIP channel.
 861  * This means flushing out any pending queues, and then returning. This
 862  * call is serialized against other ldisc functions.
 863  *
 864  * We also use this method fo a hangup event
 865  */
 866
 867 static void slip_close(struct tty_struct *tty)
 868 {
 869         struct slip *sl = tty->disc_data;
 870
 871         /* First make sure we're connected. */
 872         if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty)
 873                 return;
 874
 875         tty->disc_data = NULL;
 876         sl->tty = NULL;
 877
 878         /* VSV = very important to remove timers */
 879 #ifdef CONFIG_SLIP_SMART
 880         del_timer_sync(&sl->keepalive_timer);
 881         del_timer_sync(&sl->outfill_timer);
 882 #endif
 883         /* Flush network side */
 884         unregister_netdev(sl->dev);
 885         /* This will complete via sl_free_netdev */
 886 }
 887
 888 static int slip_hangup(struct tty_struct *tty)
 889 {
 890         slip_close(tty);
 891         return 0;
 892 }
 893  /************************************************************************
 894   *                     STANDARD SLIP ENCAPSULATION                      *
 895   ************************************************************************/
 896
 897 static int slip_esc(unsigned char *s, unsigned char *d, int len)
 898 {
 899         unsigned char *ptr = d;
 900         unsigned char c;
 901
 902         /*
 903          * Send an initial END character to flush out any
 904          * data that may have accumulated in the receiver
 905          * due to line noise.
 906          */
 907
 908         *ptr++ = END;
 909
 910         /*
 911          * For each byte in the packet, send the appropriate
 912          * character sequence, according to the SLIP protocol.
 913          */
 914
 915         while (len-- > 0) {
 916                 switch (c = *s++) {
 917                 case END:
 918                         *ptr++ = ESC;
 919                         *ptr++ = ESC_END;
 920                         break;
 921                 case ESC:
 922                         *ptr++ = ESC;
 923                         *ptr++ = ESC_ESC;
 924                         break;
 925                 default:
 926                         *ptr++ = c;
 927                         break;
 928                 }
 929         }
 930         *ptr++ = END;
 931         return ptr - d;
 932 }
 933
 934 static void slip_unesc(struct slip *sl, unsigned char s)
 935 {
 936
 937         switch (s) {
 938         case END:
 939 #ifdef CONFIG_SLIP_SMART
 940                 /* drop keeptest bit = VSV */
 941                 if (test_bit(SLF_KEEPTEST, &sl->flags))
 942                         clear_bit(SLF_KEEPTEST, &sl->flags);
 943 #endif
 944
 945                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
 946                     (sl->rcount > 2))
 947                         sl_bump(sl);
 948                 clear_bit(SLF_ESCAPE, &sl->flags);
 949                 sl->rcount = 0;
 950                 return;
 951
 952         case ESC:
 953                 set_bit(SLF_ESCAPE, &sl->flags);
 954                 return;
 955         case ESC_ESC:
 956                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 957                         s = ESC;
 958                 break;
 959         case ESC_END:
 960                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 961                         s = END;
 962                 break;
 963         }
 964         if (!test_bit(SLF_ERROR, &sl->flags))  {
 965                 if (sl->rcount < sl->buffsize)  {
 966                         sl->rbuff[sl->rcount++] = s;
 967                         return;
 968                 }
 969                 sl->dev->stats.rx_over_errors++;
 970                 set_bit(SLF_ERROR, &sl->flags);
 971         }
 972 }
 973
 974
 975 #ifdef CONFIG_SLIP_MODE_SLIP6
 976 /************************************************************************
 977  *                       6 BIT SLIP ENCAPSULATION                       *
 978  ************************************************************************/
 979
 980 static int slip_esc6(unsigned char *s, unsigned char *d, int len)
 981 {
 982         unsigned char *ptr = d;
 983         unsigned char c;
 984         int i;
 985         unsigned short v = 0;
 986         short bits = 0;
 987
 988         /*
 989          * Send an initial END character to flush out any
 990          * data that may have accumulated in the receiver
 991          * due to line noise.
 992          */
 993
 994         *ptr++ = 0x70;
 995
 996         /*
 997          * Encode the packet into printable ascii characters
 998          */
 999
1000         for (i = 0; i < len; ++i) {
1001                 v = (v << 8) | s[i];
1002                 bits += 8;
1003                 while (bits >= 6) {
1004                         bits -= 6;
1005                         c = 0x30 + ((v >> bits) & 0x3F);
1006                         *ptr++ = c;
1007                 }
1008         }
1009         if (bits) {
1010                 c = 0x30 + ((v << (6 - bits)) & 0x3F);
1011                 *ptr++ = c;
1012         }
1013         *ptr++ = 0x70;
1014         return ptr - d;
1015 }
1016
1017 static void slip_unesc6(struct slip *sl, unsigned char s)
1018 {
1019         unsigned char c;
1020
1021         if (s == 0x70) {
1022 #ifdef CONFIG_SLIP_SMART
1023                 /* drop keeptest bit = VSV */
1024                 if (test_bit(SLF_KEEPTEST, &sl->flags))
1025                         clear_bit(SLF_KEEPTEST, &sl->flags);
1026 #endif
1027
1028                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
1029                     (sl->rcount > 2))
1030                         sl_bump(sl);
1031                 sl->rcount = 0;
1032                 sl->xbits = 0;
1033                 sl->xdata = 0;
1034         } else if (s >= 0x30 && s < 0x70) {
1035                 sl->xdata = (sl->xdata << 6) | ((s - 0x30) & 0x3F);
1036                 sl->xbits += 6;
1037                 if (sl->xbits >= 8) {
1038                         sl->xbits -= 8;
1039                         c = (unsigned char)(sl->xdata >> sl->xbits);
1040                         if (!test_bit(SLF_ERROR, &sl->flags))  {
1041                                 if (sl->rcount < sl->buffsize)  {
1042                                         sl->rbuff[sl->rcount++] = c;
1043                                         return;
1044                                 }
1045                                 sl->dev->stats.rx_over_errors++;
1046                                 set_bit(SLF_ERROR, &sl->flags);
1047                         }
1048                 }
1049         }
1050 }
1051 #endif /* CONFIG_SLIP_MODE_SLIP6 */
1052
1053 /* Perform I/O control on an active SLIP channel. */
1054 static int slip_ioctl(struct tty_struct *tty, struct file *file,
1055                                         unsigned int cmd, unsigned long arg)
1056 {
1057         struct slip *sl = tty->disc_data;
1058         unsigned int tmp;
1059         int __user *p = (int __user *)arg;
1060
1061         /* First make sure we're connected. */
1062         if (!sl || sl->magic != SLIP_MAGIC)
1063                 return -EINVAL;
1064
1065         switch (cmd) {
1066         case SIOCGIFNAME:
1067                 tmp = strlen(sl->dev->name) + 1;
1068                 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
1069                         return -EFAULT;
1070                 return 0;
1071
1072         case SIOCGIFENCAP:
1073                 if (put_user(sl->mode, p))
1074                         return -EFAULT;
1075                 return 0;
1076
1077         case SIOCSIFENCAP:
1078                 if (get_user(tmp, p))
1079                         return -EFAULT;
1080 #ifndef SL_INCLUDE_CSLIP
1081                 if (tmp & (SL_MODE_CSLIP|SL_MODE_ADAPTIVE))
1082                         return -EINVAL;
1083 #else
1084                 if ((tmp & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) ==
1085                     (SL_MODE_ADAPTIVE | SL_MODE_CSLIP))
1086                         /* return -EINVAL; */
1087                         tmp &= ~SL_MODE_ADAPTIVE;
1088 #endif
1089 #ifndef CONFIG_SLIP_MODE_SLIP6
1090                 if (tmp & SL_MODE_SLIP6)
1091                         return -EINVAL;
1092 #endif
1093                 sl->mode = tmp;
1094                 sl->dev->type = ARPHRD_SLIP + sl->mode;
1095                 return 0;
1096
1097         case SIOCSIFHWADDR:
1098                 return -EINVAL;
1099
1100 #ifdef CONFIG_SLIP_SMART
1101         /* VSV changes start here */
1102         case SIOCSKEEPALIVE:
1103                 if (get_user(tmp, p))
1104                         return -EFAULT;
1105                 if (tmp > 255) /* max for unchar */
1106                         return -EINVAL;
1107
1108                 spin_lock_bh(&sl->lock);
1109                 if (!sl->tty) {
1110                         spin_unlock_bh(&sl->lock);
1111                         return -ENODEV;
1112                 }
1113                 sl->keepalive = (u8)tmp;
1114                 if (sl->keepalive != 0) {
1115                         mod_timer(&sl->keepalive_timer,
1116                                         jiffies + sl->keepalive * HZ);
1117                         set_bit(SLF_KEEPTEST, &sl->flags);
1118                 } else
1119                         del_timer(&sl->keepalive_timer);
1120                 spin_unlock_bh(&sl->lock);
1121                 return 0;
1122
1123         case SIOCGKEEPALIVE:
1124                 if (put_user(sl->keepalive, p))
1125                         return -EFAULT;
1126                 return 0;
1127
1128         case SIOCSOUTFILL:
1129                 if (get_user(tmp, p))
1130                         return -EFAULT;
1131                 if (tmp > 255) /* max for unchar */
1132                         return -EINVAL;
1133                 spin_lock_bh(&sl->lock);
1134                 if (!sl->tty) {
1135                         spin_unlock_bh(&sl->lock);
1136                         return -ENODEV;
1137                 }
1138                 sl->outfill = (u8)tmp;
1139                 if (sl->outfill != 0) {
1140                         mod_timer(&sl->outfill_timer,
1141                                                 jiffies + sl->outfill * HZ);
1142                         set_bit(SLF_OUTWAIT, &sl->flags);
1143                 } else
1144                         del_timer(&sl->outfill_timer);
1145                 spin_unlock_bh(&sl->lock);
1146                 return 0;
1147
1148         case SIOCGOUTFILL:
1149                 if (put_user(sl->outfill, p))
1150                         return -EFAULT;
1151                 return 0;
1152         /* VSV changes end */
1153 #endif
1154         default:
1155                 return tty_mode_ioctl(tty, file, cmd, arg);
1156         }
1157 }
1158
1159 #ifdef CONFIG_COMPAT
1160 static long slip_compat_ioctl(struct tty_struct *tty, struct file *file,
1161                                         unsigned int cmd, unsigned long arg)
1162 {
1163         switch (cmd) {
1164         case SIOCGIFNAME:
1165         case SIOCGIFENCAP:
1166         case SIOCSIFENCAP:
1167         case SIOCSIFHWADDR:
1168         case SIOCSKEEPALIVE:
1169         case SIOCGKEEPALIVE:
1170         case SIOCSOUTFILL:
1171         case SIOCGOUTFILL:
1172                 return slip_ioctl(tty, file, cmd,
1173                                   (unsigned long)compat_ptr(arg));
1174         }
1175
1176         return -ENOIOCTLCMD;
1177 }
1178 #endif
1179
1180 /* VSV changes start here */
1181 #ifdef CONFIG_SLIP_SMART
1182 /* function do_ioctl called from net/core/dev.c
1183    to allow get/set outfill/keepalive parameter
1184    by ifconfig                                 */
1185
1186 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
1187 {
1188         struct slip *sl = netdev_priv(dev);
1189         unsigned long *p = (unsigned long *)&rq->ifr_ifru;
1190
1191         if (sl == NULL)         /* Allocation failed ?? */
1192                 return -ENODEV;
1193
1194         spin_lock_bh(&sl->lock);
1195
1196         if (!sl->tty) {
1197                 spin_unlock_bh(&sl->lock);
1198                 return -ENODEV;
1199         }
1200
1201         switch (cmd) {
1202         case SIOCSKEEPALIVE:
1203                 /* max for unchar */
1204                 if ((unsigned)*p > 255) {
1205                         spin_unlock_bh(&sl->lock);
1206                         return -EINVAL;
1207                 }
1208                 sl->keepalive = (u8)*p;
1209                 if (sl->keepalive != 0) {
1210                         sl->keepalive_timer.expires =
1211                                                 jiffies + sl->keepalive * HZ;
1212                         mod_timer(&sl->keepalive_timer,
1213                                                 jiffies + sl->keepalive * HZ);
1214                         set_bit(SLF_KEEPTEST, &sl->flags);
1215                 } else
1216                         del_timer(&sl->keepalive_timer);
1217                 break;
1218
1219         case SIOCGKEEPALIVE:
1220                 *p = sl->keepalive;
1221                 break;
1222
1223         case SIOCSOUTFILL:
1224                 if ((unsigned)*p > 255) { /* max for unchar */
1225                         spin_unlock_bh(&sl->lock);
1226                         return -EINVAL;
1227                 }
1228                 sl->outfill = (u8)*p;
1229                 if (sl->outfill != 0) {
1230                         mod_timer(&sl->outfill_timer,
1231                                                 jiffies + sl->outfill * HZ);
1232                         set_bit(SLF_OUTWAIT, &sl->flags);
1233                 } else
1234                         del_timer(&sl->outfill_timer);
1235                 break;
1236
1237         case SIOCGOUTFILL:
1238                 *p = sl->outfill;
1239                 break;
1240
1241         case SIOCSLEASE:
1242                 /* Resolve race condition, when ioctl'ing hanged up
1243                    and opened by another process device.
1244                  */
1245                 if (sl->tty != current->signal->tty &&
1246                                                 sl->pid != current->pid) {
1247                         spin_unlock_bh(&sl->lock);
1248                         return -EPERM;
1249                 }
1250                 sl->leased = 0;
1251                 if (*p)
1252                         sl->leased = 1;
1253                 break;
1254
1255         case SIOCGLEASE:
1256                 *p = sl->leased;
1257         }
1258         spin_unlock_bh(&sl->lock);
1259         return 0;
1260 }
1261 #endif
1262 /* VSV changes end */
1263
1264 static struct tty_ldisc_ops sl_ldisc = {
1265         .owner          = THIS_MODULE,
1266         .magic          = TTY_LDISC_MAGIC,
1267         .name           = "slip",
1268         .open           = slip_open,
1269         .close          = slip_close,
1270         .hangup         = slip_hangup,
1271         .ioctl          = slip_ioctl,
1272 #ifdef CONFIG_COMPAT
1273         .compat_ioctl   = slip_compat_ioctl,
1274 #endif
1275         .receive_buf    = slip_receive_buf,
1276         .write_wakeup   = slip_write_wakeup,
1277 };
1278
1279 static int __init slip_init(void)
1280 {
1281         int status;
1282
1283         if (slip_maxdev < 4)
1284                 slip_maxdev = 4; /* Sanity */
1285
1286         printk(KERN_INFO "SLIP: version %s (dynamic channels, max=%d)"
1287 #ifdef CONFIG_SLIP_MODE_SLIP6
1288                " (6 bit encapsulation enabled)"
1289 #endif
1290                ".\n",
1291                SLIP_VERSION, slip_maxdev);
1292 #if defined(SL_INCLUDE_CSLIP)
1293         printk(KERN_INFO "CSLIP: code copyright 1989 Regents of the University of California.\n");
1294 #endif
1295 #ifdef CONFIG_SLIP_SMART
1296         printk(KERN_INFO "SLIP linefill/keepalive option.\n");
1297 #endif
1298
1299         slip_devs = kzalloc(sizeof(struct net_device *)*slip_maxdev,
1300                                                                 GFP_KERNEL);
1301         if (!slip_devs)
1302                 return -ENOMEM;
1303
1304         /* Fill in our line protocol discipline, and register it */
1305         status = tty_register_ldisc(N_SLIP, &sl_ldisc);
1306         if (status != 0) {
1307                 printk(KERN_ERR "SLIP: can't register line discipline (err = %d)\n", status);
1308                 kfree(slip_devs);
1309         }
1310         return status;
1311 }
1312
1313 static void __exit slip_exit(void)
1314 {
1315         int i;
1316         struct net_device *dev;
1317         struct slip *sl;
1318         unsigned long timeout = jiffies + HZ;
1319         int busy = 0;
1320
1321         if (slip_devs == NULL)
1322                 return;
1323
1324         /* First of all: check for active disciplines and hangup them.
1325          */
1326         do {
1327                 if (busy)
1328                         msleep_interruptible(100);
1329
1330                 busy = 0;
1331                 for (i = 0; i < slip_maxdev; i++) {
1332                         dev = slip_devs[i];
1333                         if (!dev)
1334                                 continue;
1335                         sl = netdev_priv(dev);
1336                         spin_lock_bh(&sl->lock);
1337                         if (sl->tty) {
1338                                 busy++;
1339                                 tty_hangup(sl->tty);
1340                         }
1341                         spin_unlock_bh(&sl->lock);
1342                 }
1343         } while (busy && time_before(jiffies, timeout));
1344
1345         /* FIXME: hangup is async so we should wait when doing this second
1346            phase */
1347
1348         for (i = 0; i < slip_maxdev; i++) {
1349                 dev = slip_devs[i];
1350                 if (!dev)
1351                         continue;
1352                 slip_devs[i] = NULL;
1353
1354                 sl = netdev_priv(dev);
1355                 if (sl->tty) {
1356                         printk(KERN_ERR "%s: tty discipline still running\n",
1357                                dev->name);
1358                         /* Intentionally leak the control block. */
1359                         dev->destructor = NULL;
1360                 }
1361
1362                 unregister_netdev(dev);
1363         }
1364
1365         kfree(slip_devs);
1366         slip_devs = NULL;
1367
1368         i = tty_unregister_ldisc(N_SLIP);
1369         if (i != 0)
1370                 printk(KERN_ERR "SLIP: can't unregister line discipline (err = %d)\n", i);
1371 }
1372
1373 module_init(slip_init);
1374 module_exit(slip_exit);
1375
1376 #ifdef CONFIG_SLIP_SMART
1377 /*
1378  * This is start of the code for multislip style line checking
1379  * added by Stanislav Voronyi. All changes before marked VSV
1380  */
1381
1382 static void sl_outfill(unsigned long sls)
1383 {
1384         struct slip *sl = (struct slip *)sls;
1385
1386         spin_lock(&sl->lock);
1387
1388         if (sl->tty == NULL)
1389                 goto out;
1390
1391         if (sl->outfill) {
1392                 if (test_bit(SLF_OUTWAIT, &sl->flags)) {
1393                         /* no packets were transmitted, do outfill */
1394 #ifdef CONFIG_SLIP_MODE_SLIP6
1395                         unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END;
1396 #else
1397                         unsigned char s = END;
1398 #endif
1399                         /* put END into tty queue. Is it right ??? */
1400                         if (!netif_queue_stopped(sl->dev)) {
1401                                 /* if device busy no outfill */
1402                                 sl->tty->ops->write(sl->tty, &s, 1);
1403                         }
1404                 } else
1405                         set_bit(SLF_OUTWAIT, &sl->flags);
1406
1407                 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
1408         }
1409 out:
1410         spin_unlock(&sl->lock);
1411 }
1412
1413 static void sl_keepalive(unsigned long sls)
1414 {
1415         struct slip *sl = (struct slip *)sls;
1416
1417         spin_lock(&sl->lock);
1418
1419         if (sl->tty == NULL)
1420                 goto out;
1421
1422         if (sl->keepalive) {
1423                 if (test_bit(SLF_KEEPTEST, &sl->flags)) {
1424                         /* keepalive still high :(, we must hangup */
1425                         if (sl->outfill)
1426                                 /* outfill timer must be deleted too */
1427                                 (void)del_timer(&sl->outfill_timer);
1428                         printk(KERN_DEBUG "%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name);
1429                         /* this must hangup tty & close slip */
1430                         tty_hangup(sl->tty);
1431                         /* I think we need not something else */
1432                         goto out;
1433                 } else
1434                         set_bit(SLF_KEEPTEST, &sl->flags);
1435
1436                 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
1437         }
1438 out:
1439         spin_unlock(&sl->lock);
1440 }
1441
1442 #endif
1443 MODULE_LICENSE("GPL");
1444 MODULE_ALIAS_LDISC(N_SLIP);