drivers/net/slip.c

   1 /*
   2  * slip.c       This module implements the SLIP protocol for kernel-based
   3  *              devices like TTY.  It interfaces between a raw TTY, and the
   4  *              kernel's INET protocol layers.
   5  *
   6  * Version:     @(#)slip.c      0.8.3   12/24/94
   7  *
   8  * Authors:     Laurence Culhane, <loz@holmes.demon.co.uk>
   9  *              Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
  10  *
  11  * Fixes:
  12  *              Alan Cox        :       Sanity checks and avoid tx overruns.
  13  *                                      Has a new sl->mtu field.
  14  *              Alan Cox        :       Found cause of overrun. ifconfig sl0
  15  *                                      mtu upwards. Driver now spots this
  16  *                                      and grows/shrinks its buffers(hack!).
  17  *                                      Memory leak if you run out of memory
  18  *                                      setting up a slip driver fixed.
  19  *              Matt Dillon     :       Printable slip (borrowed from NET2E)
  20  *      Pauline Middelink       :       Slip driver fixes.
  21  *              Alan Cox        :       Honours the old SL_COMPRESSED flag
  22  *              Alan Cox        :       KISS AX.25 and AXUI IP support
  23  *              Michael Riepe   :       Automatic CSLIP recognition added
  24  *              Charles Hedrick :       CSLIP header length problem fix.
  25  *              Alan Cox        :       Corrected non-IP cases of the above.
  26  *              Alan Cox        :       Now uses hardware type as per FvK.
  27  *              Alan Cox        :       Default to 192.168.0.0 (RFC 1597)
  28  *              A.N.Kuznetsov   :       dev_tint() recursion fix.
  29  *      Dmitry Gorodchanin      :       SLIP memory leaks
  30  *      Dmitry Gorodchanin      :       Code cleanup. Reduce tty driver
  31  *                                      buffering from 4096 to 256 bytes.
  32  *                                      Improving SLIP response time.
  33  *                                      CONFIG_SLIP_MODE_SLIP6.
  34  *                                      ifconfig sl? up & down now works
  35  *                                      correctly.
  36  *                                      Modularization.
  37  *              Alan Cox        :       Oops - fix AX.25 buffer lengths
  38  *      Dmitry Gorodchanin      :       Even more cleanups. Preserve CSLIP
  39  *                                      statistics. Include CSLIP code only
  40  *                                      if it really needed.
  41  *              Alan Cox        :       Free slhc buffers in the right place.
  42  *              Alan Cox        :       Allow for digipeated IP over AX.25
  43  *              Matti Aarnio    :       Dynamic SLIP devices, with ideas taken
  44  *                                      from Jim Freeman's <jfree@caldera.com>
  45  *                                      dynamic PPP devices.  We do NOT kfree()
  46  *                                      device entries, just reg./unreg. them
  47  *                                      as they are needed.  We kfree() them
  48  *                                      at module cleanup.
  49  *                                      With MODULE-loading ``insmod'', user
  50  *                                      can issue parameter:  slip_maxdev=1024
  51  *                                      (Or how much he/she wants.. Default
  52  *                                      is 256)
  53  *      Stanislav Voronyi       :       Slip line checking, with ideas taken
  54  *                                      from multislip BSDI driver which was
  55  *                                      written by Igor Chechik, RELCOM Corp.
  56  *                                      Only algorithms have been ported to
  57  *                                      Linux SLIP driver.
  58  *      Vitaly E. Lavrov        :       Sane behaviour on tty hangup.
  59  *      Alexey Kuznetsov        :       Cleanup interfaces to tty & netdevice
  60  *                                      modules.
  61  */
  62
  63 #define SL_CHECK_TRANSMIT
  64 #include <linux/module.h>
  65 #include <linux/moduleparam.h>
  66
  67 #include <asm/system.h>
  68 #include <asm/uaccess.h>
  69 #include <linux/bitops.h>
  70 #include <linux/sched.h>
  71 #include <linux/string.h>
  72 #include <linux/mm.h>
  73 #include <linux/interrupt.h>
  74 #include <linux/in.h>
  75 #include <linux/tty.h>
  76 #include <linux/errno.h>
  77 #include <linux/netdevice.h>
  78 #include <linux/etherdevice.h>
  79 #include <linux/skbuff.h>
  80 #include <linux/rtnetlink.h>
  81 #include <linux/if_arp.h>
  82 #include <linux/if_slip.h>
  83 #include <linux/compat.h>
  84 #include <linux/delay.h>
  85 #include <linux/init.h>
  86 #include <linux/slab.h>
  87 #include "slip.h"
  88 #ifdef CONFIG_INET
  89 #include <linux/ip.h>
  90 #include <linux/tcp.h>
  91 #include <net/slhc_vj.h>
  92 #endif
  93
  94 #define SLIP_VERSION    "0.8.4-NET3.019-NEWTTY"
  95
  96 static struct net_device **slip_devs;
  97
  98 static int slip_maxdev = SL_NRUNIT;
  99 module_param(slip_maxdev, int, 0);
 100 MODULE_PARM_DESC(slip_maxdev, "Maximum number of slip devices");
 101
 102 static int slip_esc(unsigned char *p, unsigned char *d, int len);
 103 static void slip_unesc(struct slip *sl, unsigned char c);
 104 #ifdef CONFIG_SLIP_MODE_SLIP6
 105 static int slip_esc6(unsigned char *p, unsigned char *d, int len);
 106 static void slip_unesc6(struct slip *sl, unsigned char c);
 107 #endif
 108 #ifdef CONFIG_SLIP_SMART
 109 static void sl_keepalive(unsigned long sls);
 110 static void sl_outfill(unsigned long sls);
 111 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
 112 #endif
 113
 114 /********************************
 115 *  Buffer administration routines:
 116 *       sl_alloc_bufs()
 117 *       sl_free_bufs()
 118 *       sl_realloc_bufs()
 119 *
 120 * NOTE: sl_realloc_bufs != sl_free_bufs + sl_alloc_bufs, because
 121 *       sl_realloc_bufs provides strong atomicity and reallocation
 122 *       on actively running device.
 123 *********************************/
 124
 125 /*
 126    Allocate channel buffers.
 127  */
 128
 129 static int sl_alloc_bufs(struct slip *sl, int mtu)
 130 {
 131         int err = -ENOBUFS;
 132         unsigned long len;
 133         char *rbuff = NULL;
 134         char *xbuff = NULL;
 135 #ifdef SL_INCLUDE_CSLIP
 136         char *cbuff = NULL;
 137         struct slcompress *slcomp = NULL;
 138 #endif
 139
 140         /*
 141          * Allocate the SLIP frame buffers:
 142          *
 143          * rbuff        Receive buffer.
 144          * xbuff        Transmit buffer.
 145          * cbuff        Temporary compression buffer.
 146          */
 147         len = mtu * 2;
 148
 149         /*
 150          * allow for arrival of larger UDP packets, even if we say not to
 151          * also fixes a bug in which SunOS sends 512-byte packets even with
 152          * an MSS of 128
 153          */
 154         if (len < 576 * 2)
 155                 len = 576 * 2;
 156         rbuff = kmalloc(len + 4, GFP_KERNEL);
 157         if (rbuff == NULL)
 158                 goto err_exit;
 159         xbuff = kmalloc(len + 4, GFP_KERNEL);
 160         if (xbuff == NULL)
 161                 goto err_exit;
 162 #ifdef SL_INCLUDE_CSLIP
 163         cbuff = kmalloc(len + 4, GFP_KERNEL);
 164         if (cbuff == NULL)
 165                 goto err_exit;
 166         slcomp = slhc_init(16, 16);
 167         if (slcomp == NULL)
 168                 goto err_exit;
 169 #endif
 170         spin_lock_bh(&sl->lock);
 171         if (sl->tty == NULL) {
 172                 spin_unlock_bh(&sl->lock);
 173                 err = -ENODEV;
 174                 goto err_exit;
 175         }
 176         sl->mtu      = mtu;
 177         sl->buffsize = len;
 178         sl->rcount   = 0;
 179         sl->xleft    = 0;
 180         rbuff = xchg(&sl->rbuff, rbuff);
 181         xbuff = xchg(&sl->xbuff, xbuff);
 182 #ifdef SL_INCLUDE_CSLIP
 183         cbuff = xchg(&sl->cbuff, cbuff);
 184         slcomp = xchg(&sl->slcomp, slcomp);
 185 #endif
 186 #ifdef CONFIG_SLIP_MODE_SLIP6
 187         sl->xdata    = 0;
 188         sl->xbits    = 0;
 189 #endif
 190         spin_unlock_bh(&sl->lock);
 191         err = 0;
 192
 193         /* Cleanup */
 194 err_exit:
 195 #ifdef SL_INCLUDE_CSLIP
 196         kfree(cbuff);
 197         slhc_free(slcomp);
 198 #endif
 199         kfree(xbuff);
 200         kfree(rbuff);
 201         return err;
 202 }
 203
 204 /* Free a SLIP channel buffers. */
 205 static void sl_free_bufs(struct slip *sl)
 206 {
 207         /* Free all SLIP frame buffers. */
 208         kfree(xchg(&sl->rbuff, NULL));
 209         kfree(xchg(&sl->xbuff, NULL));
 210 #ifdef SL_INCLUDE_CSLIP
 211         kfree(xchg(&sl->cbuff, NULL));
 212         slhc_free(xchg(&sl->slcomp, NULL));
 213 #endif
 214 }
 215
 216 /*
 217    Reallocate slip channel buffers.
 218  */
 219
 220 static int sl_realloc_bufs(struct slip *sl, int mtu)
 221 {
 222         int err = 0;
 223         struct net_device *dev = sl->dev;
 224         unsigned char *xbuff, *rbuff;
 225 #ifdef SL_INCLUDE_CSLIP
 226         unsigned char *cbuff;
 227 #endif
 228         int len = mtu * 2;
 229
 230 /*
 231  * allow for arrival of larger UDP packets, even if we say not to
 232  * also fixes a bug in which SunOS sends 512-byte packets even with
 233  * an MSS of 128
 234  */
 235         if (len < 576 * 2)
 236                 len = 576 * 2;
 237
 238         xbuff = kmalloc(len + 4, GFP_ATOMIC);
 239         rbuff = kmalloc(len + 4, GFP_ATOMIC);
 240 #ifdef SL_INCLUDE_CSLIP
 241         cbuff = kmalloc(len + 4, GFP_ATOMIC);
 242 #endif
 243
 244
 245 #ifdef SL_INCLUDE_CSLIP
 246         if (xbuff == NULL || rbuff == NULL || cbuff == NULL)  {
 247 #else
 248         if (xbuff == NULL || rbuff == NULL)  {
 249 #endif
 250                 if (mtu > sl->mtu) {
 251                         printk(KERN_WARNING "%s: unable to grow slip buffers, MTU change cancelled.\n",
 252                                dev->name);
 253                         err = -ENOBUFS;
 254                 }
 255                 goto done;
 256         }
 257         spin_lock_bh(&sl->lock);
 258
 259         err = -ENODEV;
 260         if (sl->tty == NULL)
 261                 goto done_on_bh;
 262
 263         xbuff    = xchg(&sl->xbuff, xbuff);
 264         rbuff    = xchg(&sl->rbuff, rbuff);
 265 #ifdef SL_INCLUDE_CSLIP
 266         cbuff    = xchg(&sl->cbuff, cbuff);
 267 #endif
 268         if (sl->xleft)  {
 269                 if (sl->xleft <= len)  {
 270                         memcpy(sl->xbuff, sl->xhead, sl->xleft);
 271                 } else  {
 272                         sl->xleft = 0;
 273                         dev->stats.tx_dropped++;
 274                 }
 275         }
 276         sl->xhead = sl->xbuff;
 277
 278         if (sl->rcount)  {
 279                 if (sl->rcount <= len) {
 280                         memcpy(sl->rbuff, rbuff, sl->rcount);
 281                 } else  {
 282                         sl->rcount = 0;
 283                         dev->stats.rx_over_errors++;
 284                         set_bit(SLF_ERROR, &sl->flags);
 285                 }
 286         }
 287         sl->mtu      = mtu;
 288         dev->mtu      = mtu;
 289         sl->buffsize = len;
 290         err = 0;
 291
 292 done_on_bh:
 293         spin_unlock_bh(&sl->lock);
 294
 295 done:
 296         kfree(xbuff);
 297         kfree(rbuff);
 298 #ifdef SL_INCLUDE_CSLIP
 299         kfree(cbuff);
 300 #endif
 301         return err;
 302 }
 303
 304
 305 /* Set the "sending" flag.  This must be atomic hence the set_bit. */
 306 static inline void sl_lock(struct slip *sl)
 307 {
 308         netif_stop_queue(sl->dev);
 309 }
 310
 311
 312 /* Clear the "sending" flag.  This must be atomic, hence the ASM. */
 313 static inline void sl_unlock(struct slip *sl)
 314 {
 315         netif_wake_queue(sl->dev);
 316 }
 317
 318 /* Send one completely decapsulated IP datagram to the IP layer. */
 319 static void sl_bump(struct slip *sl)
 320 {
 321         struct net_device *dev = sl->dev;
 322         struct sk_buff *skb;
 323         int count;
 324
 325         count = sl->rcount;
 326 #ifdef SL_INCLUDE_CSLIP
 327         if (sl->mode & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) {
 328                 unsigned char c = sl->rbuff[0];
 329                 if (c & SL_TYPE_COMPRESSED_TCP) {
 330                         /* ignore compressed packets when CSLIP is off */
 331                         if (!(sl->mode & SL_MODE_CSLIP)) {
 332                                 printk(KERN_WARNING "%s: compressed packet ignored\n", dev->name);
 333                                 return;
 334                         }
 335                         /* make sure we've reserved enough space for uncompress
 336                            to use */
 337                         if (count + 80 > sl->buffsize) {
 338                                 dev->stats.rx_over_errors++;
 339                                 return;
 340                         }
 341                         count = slhc_uncompress(sl->slcomp, sl->rbuff, count);
 342                         if (count <= 0)
 343                                 return;
 344                 } else if (c >= SL_TYPE_UNCOMPRESSED_TCP) {
 345                         if (!(sl->mode & SL_MODE_CSLIP)) {
 346                                 /* turn on header compression */
 347                                 sl->mode |= SL_MODE_CSLIP;
 348                                 sl->mode &= ~SL_MODE_ADAPTIVE;
 349                                 printk(KERN_INFO "%s: header compression turned on\n", dev->name);
 350                         }
 351                         sl->rbuff[0] &= 0x4f;
 352                         if (slhc_remember(sl->slcomp, sl->rbuff, count) <= 0)
 353                                 return;
 354                 }
 355         }
 356 #endif  /* SL_INCLUDE_CSLIP */
 357
 358         dev->stats.rx_bytes += count;
 359
 360         skb = dev_alloc_skb(count);
 361         if (skb == NULL) {
 362                 printk(KERN_WARNING "%s: memory squeeze, dropping packet.\n", dev->name);
 363                 dev->stats.rx_dropped++;
 364                 return;
 365         }
 366         skb->dev = dev;
 367         memcpy(skb_put(skb, count), sl->rbuff, count);
 368         skb_reset_mac_header(skb);
 369         skb->protocol = htons(ETH_P_IP);
 370         netif_rx(skb);
 371         dev->stats.rx_packets++;
 372 }
 373
 374 /* Encapsulate one IP datagram and stuff into a TTY queue. */
 375 static void sl_encaps(struct slip *sl, unsigned char *icp, int len)
 376 {
 377         unsigned char *p;
 378         int actual, count;
 379
 380         if (len > sl->mtu) {            /* Sigh, shouldn't occur BUT ... */
 381                 printk(KERN_WARNING "%s: truncating oversized transmit packet!\n", sl->dev->name);
 382                 sl->dev->stats.tx_dropped++;
 383                 sl_unlock(sl);
 384                 return;
 385         }
 386
 387         p = icp;
 388 #ifdef SL_INCLUDE_CSLIP
 389         if (sl->mode & SL_MODE_CSLIP)
 390                 len = slhc_compress(sl->slcomp, p, len, sl->cbuff, &p, 1);
 391 #endif
 392 #ifdef CONFIG_SLIP_MODE_SLIP6
 393         if (sl->mode & SL_MODE_SLIP6)
 394                 count = slip_esc6(p, (unsigned char *) sl->xbuff, len);
 395         else
 396 #endif
 397                 count = slip_esc(p, (unsigned char *) sl->xbuff, len);
 398
 399         /* Order of next two lines is *very* important.
 400          * When we are sending a little amount of data,
 401          * the transfer may be completed inside the ops->write()
 402          * routine, because it's running with interrupts enabled.
 403          * In this case we *never* got WRITE_WAKEUP event,
 404          * if we did not request it before write operation.
 405          *       14 Oct 1994  Dmitry Gorodchanin.
 406          */
 407         set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 408         actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
 409 #ifdef SL_CHECK_TRANSMIT
 410         sl->dev->trans_start = jiffies;
 411 #endif
 412         sl->xleft = count - actual;
 413         sl->xhead = sl->xbuff + actual;
 414 #ifdef CONFIG_SLIP_SMART
 415         /* VSV */
 416         clear_bit(SLF_OUTWAIT, &sl->flags);     /* reset outfill flag */
 417 #endif
 418 }
 419
 420 /*
 421  * Called by the driver when there's room for more data.  If we have
 422  * more packets to send, we send them here.
 423  */
 424 static void slip_write_wakeup(struct tty_struct *tty)
 425 {
 426         int actual;
 427         struct slip *sl = tty->disc_data;
 428
 429         /* First make sure we're connected. */
 430         if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
 431                 return;
 432
 433         if (sl->xleft <= 0)  {
 434                 /* Now serial buffer is almost free & we can start
 435                  * transmission of another packet */
 436                 sl->dev->stats.tx_packets++;
 437                 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 438                 sl_unlock(sl);
 439                 return;
 440         }
 441
 442         actual = tty->ops->write(tty, sl->xhead, sl->xleft);
 443         sl->xleft -= actual;
 444         sl->xhead += actual;
 445 }
 446
 447 static void sl_tx_timeout(struct net_device *dev)
 448 {
 449         struct slip *sl = netdev_priv(dev);
 450
 451         spin_lock(&sl->lock);
 452
 453         if (netif_queue_stopped(dev)) {
 454                 if (!netif_running(dev))
 455                         goto out;
 456
 457                 /* May be we must check transmitter timeout here ?
 458                  *      14 Oct 1994 Dmitry Gorodchanin.
 459                  */
 460 #ifdef SL_CHECK_TRANSMIT
 461                 if (time_before(jiffies, dev_trans_start(dev) + 20 * HZ))  {
 462                         /* 20 sec timeout not reached */
 463                         goto out;
 464                 }
 465                 printk(KERN_WARNING "%s: transmit timed out, %s?\n",
 466                         dev->name,
 467                         (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
 468                                 "bad line quality" : "driver error");
 469                 sl->xleft = 0;
 470                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 471                 sl_unlock(sl);
 472 #endif
 473         }
 474 out:
 475         spin_unlock(&sl->lock);
 476 }
 477
 478
 479 /* Encapsulate an IP datagram and kick it into a TTY queue. */
 480 static netdev_tx_t
 481 sl_xmit(struct sk_buff *skb, struct net_device *dev)
 482 {
 483         struct slip *sl = netdev_priv(dev);
 484
 485         spin_lock(&sl->lock);
 486         if (!netif_running(dev)) {
 487                 spin_unlock(&sl->lock);
 488                 printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name);
 489                 dev_kfree_skb(skb);
 490                 return NETDEV_TX_OK;
 491         }
 492         if (sl->tty == NULL) {
 493                 spin_unlock(&sl->lock);
 494                 dev_kfree_skb(skb);
 495                 return NETDEV_TX_OK;
 496         }
 497
 498         sl_lock(sl);
 499         dev->stats.tx_bytes += skb->len;
 500         sl_encaps(sl, skb->data, skb->len);
 501         spin_unlock(&sl->lock);
 502
 503         dev_kfree_skb(skb);
 504         return NETDEV_TX_OK;
 505 }
 506
 507
 508 /******************************************
 509  *   Routines looking at netdevice side.
 510  ******************************************/
 511
 512 /* Netdevice UP -> DOWN routine */
 513
 514 static int
 515 sl_close(struct net_device *dev)
 516 {
 517         struct slip *sl = netdev_priv(dev);
 518
 519         spin_lock_bh(&sl->lock);
 520         if (sl->tty)
 521                 /* TTY discipline is running. */
 522                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 523         netif_stop_queue(dev);
 524         sl->rcount   = 0;
 525         sl->xleft    = 0;
 526         spin_unlock_bh(&sl->lock);
 527
 528         return 0;
 529 }
 530
 531 /* Netdevice DOWN -> UP routine */
 532
 533 static int sl_open(struct net_device *dev)
 534 {
 535         struct slip *sl = netdev_priv(dev);
 536
 537         if (sl->tty == NULL)
 538                 return -ENODEV;
 539
 540         sl->flags &= (1 << SLF_INUSE);
 541         netif_start_queue(dev);
 542         return 0;
 543 }
 544
 545 /* Netdevice change MTU request */
 546
 547 static int sl_change_mtu(struct net_device *dev, int new_mtu)
 548 {
 549         struct slip *sl = netdev_priv(dev);
 550
 551         if (new_mtu < 68 || new_mtu > 65534)
 552                 return -EINVAL;
 553
 554         if (new_mtu != dev->mtu)
 555                 return sl_realloc_bufs(sl, new_mtu);
 556         return 0;
 557 }
 558
 559 /* Netdevice get statistics request */
 560
 561 static struct rtnl_link_stats64 *
 562 sl_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
 563 {
 564         struct net_device_stats *devstats = &dev->stats;
 565         unsigned long c_rx_dropped = 0;
 566 #ifdef SL_INCLUDE_CSLIP
 567         unsigned long c_rx_fifo_errors = 0;
 568         unsigned long c_tx_fifo_errors = 0;
 569         unsigned long c_collisions = 0;
 570         struct slip *sl = netdev_priv(dev);
 571         struct slcompress *comp = sl->slcomp;
 572
 573         if (comp) {
 574                 c_rx_fifo_errors = comp->sls_i_compressed;
 575                 c_rx_dropped     = comp->sls_i_tossed;
 576                 c_tx_fifo_errors = comp->sls_o_compressed;
 577                 c_collisions     = comp->sls_o_misses;
 578         }
 579         stats->rx_fifo_errors = sl->rx_compressed + c_rx_fifo_errors;
 580         stats->tx_fifo_errors = sl->tx_compressed + c_tx_fifo_errors;
 581         stats->collisions     = sl->tx_misses + c_collisions;
 582 #endif
 583         stats->rx_packets     = devstats->rx_packets;
 584         stats->tx_packets     = devstats->tx_packets;
 585         stats->rx_bytes       = devstats->rx_bytes;
 586         stats->tx_bytes       = devstats->tx_bytes;
 587         stats->rx_dropped     = devstats->rx_dropped + c_rx_dropped;
 588         stats->tx_dropped     = devstats->tx_dropped;
 589         stats->tx_errors      = devstats->tx_errors;
 590         stats->rx_errors      = devstats->rx_errors;
 591         stats->rx_over_errors = devstats->rx_over_errors;
 592
 593         return stats;
 594 }
 595
 596 /* Netdevice register callback */
 597
 598 static int sl_init(struct net_device *dev)
 599 {
 600         struct slip *sl = netdev_priv(dev);
 601
 602         /*
 603          *      Finish setting up the DEVICE info.
 604          */
 605
 606         dev->mtu                = sl->mtu;
 607         dev->type               = ARPHRD_SLIP + sl->mode;
 608 #ifdef SL_CHECK_TRANSMIT
 609         dev->watchdog_timeo     = 20*HZ;
 610 #endif
 611         return 0;
 612 }
 613
 614
 615 static void sl_uninit(struct net_device *dev)
 616 {
 617         struct slip *sl = netdev_priv(dev);
 618
 619         sl_free_bufs(sl);
 620 }
 621
 622 /* Hook the destructor so we can free slip devices at the right point in time */
 623 static void sl_free_netdev(struct net_device *dev)
 624 {
 625         int i = dev->base_addr;
 626         free_netdev(dev);
 627         slip_devs[i] = NULL;
 628 }
 629
 630 static const struct net_device_ops sl_netdev_ops = {
 631         .ndo_init               = sl_init,
 632         .ndo_uninit             = sl_uninit,
 633         .ndo_open               = sl_open,
 634         .ndo_stop               = sl_close,
 635         .ndo_start_xmit         = sl_xmit,
 636         .ndo_get_stats64        = sl_get_stats64,
 637         .ndo_change_mtu         = sl_change_mtu,
 638         .ndo_tx_timeout         = sl_tx_timeout,
 639 #ifdef CONFIG_SLIP_SMART
 640         .ndo_do_ioctl           = sl_ioctl,
 641 #endif
 642 };
 643
 644
 645 static void sl_setup(struct net_device *dev)
 646 {
 647         dev->netdev_ops         = &sl_netdev_ops;
 648         dev->destructor         = sl_free_netdev;
 649
 650         dev->hard_header_len    = 0;
 651         dev->addr_len           = 0;
 652         dev->tx_queue_len       = 10;
 653
 654         /* New-style flags. */
 655         dev->flags              = IFF_NOARP|IFF_POINTOPOINT|IFF_MULTICAST;
 656 }
 657
 658 /******************************************
 659   Routines looking at TTY side.
 660  ******************************************/
 661
 662
 663 /*
 664  * Handle the 'receiver data ready' interrupt.
 665  * This function is called by the 'tty_io' module in the kernel when
 666  * a block of SLIP data has been received, which can now be decapsulated
 667  * and sent on to some IP layer for further processing. This will not
 668  * be re-entered while running but other ldisc functions may be called
 669  * in parallel
 670  */
 671
 672 static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 673                                                         char *fp, int count)
 674 {
 675         struct slip *sl = tty->disc_data;
 676
 677         if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
 678                 return;
 679
 680         /* Read the characters out of the buffer */
 681         while (count--) {
 682                 if (fp && *fp++) {
 683                         if (!test_and_set_bit(SLF_ERROR, &sl->flags))
 684                                 sl->dev->stats.rx_errors++;
 685                         cp++;
 686                         continue;
 687                 }
 688 #ifdef CONFIG_SLIP_MODE_SLIP6
 689                 if (sl->mode & SL_MODE_SLIP6)
 690                         slip_unesc6(sl, *cp++);
 691                 else
 692 #endif
 693                         slip_unesc(sl, *cp++);
 694         }
 695 }
 696
 697 /************************************
 698  *  slip_open helper routines.
 699  ************************************/
 700
 701 /* Collect hanged up channels */
 702 static void sl_sync(void)
 703 {
 704         int i;
 705         struct net_device *dev;
 706         struct slip       *sl;
 707
 708         for (i = 0; i < slip_maxdev; i++) {
 709                 dev = slip_devs[i];
 710                 if (dev == NULL)
 711                         break;
 712
 713                 sl = netdev_priv(dev);
 714                 if (sl->tty || sl->leased)
 715                         continue;
 716                 if (dev->flags & IFF_UP)
 717                         dev_close(dev);
 718         }
 719 }
 720
 721
 722 /* Find a free SLIP channel, and link in this `tty' line. */
 723 static struct slip *sl_alloc(dev_t line)
 724 {
 725         int i;
 726         char name[IFNAMSIZ];
 727         struct net_device *dev = NULL;
 728         struct slip       *sl;
 729
 730         for (i = 0; i < slip_maxdev; i++) {
 731                 dev = slip_devs[i];
 732                 if (dev == NULL)
 733                         break;
 734         }
 735         /* Sorry, too many, all slots in use */
 736         if (i >= slip_maxdev)
 737                 return NULL;
 738
 739         sprintf(name, "sl%d", i);
 740         dev = alloc_netdev(sizeof(*sl), name, sl_setup);
 741         if (!dev)
 742                 return NULL;
 743
 744         dev->base_addr  = i;
 745         sl = netdev_priv(dev);
 746
 747         /* Initialize channel control data */
 748         sl->magic       = SLIP_MAGIC;
 749         sl->dev         = dev;
 750         spin_lock_init(&sl->lock);
 751         sl->mode        = SL_MODE_DEFAULT;
 752 #ifdef CONFIG_SLIP_SMART
 753         /* initialize timer_list struct */
 754         init_timer(&sl->keepalive_timer);
 755         sl->keepalive_timer.data = (unsigned long)sl;
 756         sl->keepalive_timer.function = sl_keepalive;
 757         init_timer(&sl->outfill_timer);
 758         sl->outfill_timer.data = (unsigned long)sl;
 759         sl->outfill_timer.function = sl_outfill;
 760 #endif
 761         slip_devs[i] = dev;
 762         return sl;
 763 }
 764
 765 /*
 766  * Open the high-level part of the SLIP channel.
 767  * This function is called by the TTY module when the
 768  * SLIP line discipline is called for.  Because we are
 769  * sure the tty line exists, we only have to link it to
 770  * a free SLIP channel...
 771  *
 772  * Called in process context serialized from other ldisc calls.
 773  */
 774
 775 static int slip_open(struct tty_struct *tty)
 776 {
 777         struct slip *sl;
 778         int err;
 779
 780         if (!capable(CAP_NET_ADMIN))
 781                 return -EPERM;
 782
 783         if (tty->ops->write == NULL)
 784                 return -EOPNOTSUPP;
 785
 786         /* RTnetlink lock is misused here to serialize concurrent
 787            opens of slip channels. There are better ways, but it is
 788            the simplest one.
 789          */
 790         rtnl_lock();
 791
 792         /* Collect hanged up channels. */
 793         sl_sync();
 794
 795         sl = tty->disc_data;
 796
 797         err = -EEXIST;
 798         /* First make sure we're not already connected. */
 799         if (sl && sl->magic == SLIP_MAGIC)
 800                 goto err_exit;
 801
 802         /* OK.  Find a free SLIP channel to use. */
 803         err = -ENFILE;
 804         sl = sl_alloc(tty_devnum(tty));
 805         if (sl == NULL)
 806                 goto err_exit;
 807
 808         sl->tty = tty;
 809         tty->disc_data = sl;
 810         sl->pid = current->pid;
 811
 812         if (!test_bit(SLF_INUSE, &sl->flags)) {
 813                 /* Perform the low-level SLIP initialization. */
 814                 err = sl_alloc_bufs(sl, SL_MTU);
 815                 if (err)
 816                         goto err_free_chan;
 817
 818                 set_bit(SLF_INUSE, &sl->flags);
 819
 820                 err = register_netdevice(sl->dev);
 821                 if (err)
 822                         goto err_free_bufs;
 823         }
 824
 825 #ifdef CONFIG_SLIP_SMART
 826         if (sl->keepalive) {
 827                 sl->keepalive_timer.expires = jiffies + sl->keepalive * HZ;
 828                 add_timer(&sl->keepalive_timer);
 829         }
 830         if (sl->outfill) {
 831                 sl->outfill_timer.expires = jiffies + sl->outfill * HZ;
 832                 add_timer(&sl->outfill_timer);
 833         }
 834 #endif
 835
 836         /* Done.  We have linked the TTY line to a channel. */
 837         rtnl_unlock();
 838         tty->receive_room = 65536;      /* We don't flow control */
 839
 840         /* TTY layer expects 0 on success */
 841         return 0;
 842
 843 err_free_bufs:
 844         sl_free_bufs(sl);
 845
 846 err_free_chan:
 847         sl->tty = NULL;
 848         tty->disc_data = NULL;
 849         clear_bit(SLF_INUSE, &sl->flags);
 850
 851 err_exit:
 852         rtnl_unlock();
 853
 854         /* Count references from TTY module */
 855         return err;
 856 }
 857
 858 /*
 859  * Close down a SLIP channel.
 860  * This means flushing out any pending queues, and then returning. This
 861  * call is serialized against other ldisc functions.
 862  *
 863  * We also use this method fo a hangup event
 864  */
 865
 866 static void slip_close(struct tty_struct *tty)
 867 {
 868         struct slip *sl = tty->disc_data;
 869
 870         /* First make sure we're connected. */
 871         if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty)
 872                 return;
 873
 874         tty->disc_data = NULL;
 875         sl->tty = NULL;
 876
 877         /* VSV = very important to remove timers */
 878 #ifdef CONFIG_SLIP_SMART
 879         del_timer_sync(&sl->keepalive_timer);
 880         del_timer_sync(&sl->outfill_timer);
 881 #endif
 882         /* Flush network side */
 883         unregister_netdev(sl->dev);
 884         /* This will complete via sl_free_netdev */
 885 }
 886
 887 static int slip_hangup(struct tty_struct *tty)
 888 {
 889         slip_close(tty);
 890         return 0;
 891 }
 892  /************************************************************************
 893   *                     STANDARD SLIP ENCAPSULATION                      *
 894   ************************************************************************/
 895
 896 static int slip_esc(unsigned char *s, unsigned char *d, int len)
 897 {
 898         unsigned char *ptr = d;
 899         unsigned char c;
 900
 901         /*
 902          * Send an initial END character to flush out any
 903          * data that may have accumulated in the receiver
 904          * due to line noise.
 905          */
 906
 907         *ptr++ = END;
 908
 909         /*
 910          * For each byte in the packet, send the appropriate
 911          * character sequence, according to the SLIP protocol.
 912          */
 913
 914         while (len-- > 0) {
 915                 switch (c = *s++) {
 916                 case END:
 917                         *ptr++ = ESC;
 918                         *ptr++ = ESC_END;
 919                         break;
 920                 case ESC:
 921                         *ptr++ = ESC;
 922                         *ptr++ = ESC_ESC;
 923                         break;
 924                 default:
 925                         *ptr++ = c;
 926                         break;
 927                 }
 928         }
 929         *ptr++ = END;
 930         return ptr - d;
 931 }
 932
 933 static void slip_unesc(struct slip *sl, unsigned char s)
 934 {
 935
 936         switch (s) {
 937         case END:
 938 #ifdef CONFIG_SLIP_SMART
 939                 /* drop keeptest bit = VSV */
 940                 if (test_bit(SLF_KEEPTEST, &sl->flags))
 941                         clear_bit(SLF_KEEPTEST, &sl->flags);
 942 #endif
 943
 944                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
 945                     (sl->rcount > 2))
 946                         sl_bump(sl);
 947                 clear_bit(SLF_ESCAPE, &sl->flags);
 948                 sl->rcount = 0;
 949                 return;
 950
 951         case ESC:
 952                 set_bit(SLF_ESCAPE, &sl->flags);
 953                 return;
 954         case ESC_ESC:
 955                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 956                         s = ESC;
 957                 break;
 958         case ESC_END:
 959                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 960                         s = END;
 961                 break;
 962         }
 963         if (!test_bit(SLF_ERROR, &sl->flags))  {
 964                 if (sl->rcount < sl->buffsize)  {
 965                         sl->rbuff[sl->rcount++] = s;
 966                         return;
 967                 }
 968                 sl->dev->stats.rx_over_errors++;
 969                 set_bit(SLF_ERROR, &sl->flags);
 970         }
 971 }
 972
 973
 974 #ifdef CONFIG_SLIP_MODE_SLIP6
 975 /************************************************************************
 976  *                       6 BIT SLIP ENCAPSULATION                       *
 977  ************************************************************************/
 978
 979 static int slip_esc6(unsigned char *s, unsigned char *d, int len)
 980 {
 981         unsigned char *ptr = d;
 982         unsigned char c;
 983         int i;
 984         unsigned short v = 0;
 985         short bits = 0;
 986
 987         /*
 988          * Send an initial END character to flush out any
 989          * data that may have accumulated in the receiver
 990          * due to line noise.
 991          */
 992
 993         *ptr++ = 0x70;
 994
 995         /*
 996          * Encode the packet into printable ascii characters
 997          */
 998
 999         for (i = 0; i < len; ++i) {
1000                 v = (v << 8) | s[i];
1001                 bits += 8;
1002                 while (bits >= 6) {
1003                         bits -= 6;
1004                         c = 0x30 + ((v >> bits) & 0x3F);
1005                         *ptr++ = c;
1006                 }
1007         }
1008         if (bits) {
1009                 c = 0x30 + ((v << (6 - bits)) & 0x3F);
1010                 *ptr++ = c;
1011         }
1012         *ptr++ = 0x70;
1013         return ptr - d;
1014 }
1015
1016 static void slip_unesc6(struct slip *sl, unsigned char s)
1017 {
1018         unsigned char c;
1019
1020         if (s == 0x70) {
1021 #ifdef CONFIG_SLIP_SMART
1022                 /* drop keeptest bit = VSV */
1023                 if (test_bit(SLF_KEEPTEST, &sl->flags))
1024                         clear_bit(SLF_KEEPTEST, &sl->flags);
1025 #endif
1026
1027                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
1028                     (sl->rcount > 2))
1029                         sl_bump(sl);
1030                 sl->rcount = 0;
1031                 sl->xbits = 0;
1032                 sl->xdata = 0;
1033         } else if (s >= 0x30 && s < 0x70) {
1034                 sl->xdata = (sl->xdata << 6) | ((s - 0x30) & 0x3F);
1035                 sl->xbits += 6;
1036                 if (sl->xbits >= 8) {
1037                         sl->xbits -= 8;
1038                         c = (unsigned char)(sl->xdata >> sl->xbits);
1039                         if (!test_bit(SLF_ERROR, &sl->flags))  {
1040                                 if (sl->rcount < sl->buffsize)  {
1041                                         sl->rbuff[sl->rcount++] = c;
1042                                         return;
1043                                 }
1044                                 sl->dev->stats.rx_over_errors++;
1045                                 set_bit(SLF_ERROR, &sl->flags);
1046                         }
1047                 }
1048         }
1049 }
1050 #endif /* CONFIG_SLIP_MODE_SLIP6 */
1051
1052 /* Perform I/O control on an active SLIP channel. */
1053 static int slip_ioctl(struct tty_struct *tty, struct file *file,
1054                                         unsigned int cmd, unsigned long arg)
1055 {
1056         struct slip *sl = tty->disc_data;
1057         unsigned int tmp;
1058         int __user *p = (int __user *)arg;
1059
1060         /* First make sure we're connected. */
1061         if (!sl || sl->magic != SLIP_MAGIC)
1062                 return -EINVAL;
1063
1064         switch (cmd) {
1065         case SIOCGIFNAME:
1066                 tmp = strlen(sl->dev->name) + 1;
1067                 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
1068                         return -EFAULT;
1069                 return 0;
1070
1071         case SIOCGIFENCAP:
1072                 if (put_user(sl->mode, p))
1073                         return -EFAULT;
1074                 return 0;
1075
1076         case SIOCSIFENCAP:
1077                 if (get_user(tmp, p))
1078                         return -EFAULT;
1079 #ifndef SL_INCLUDE_CSLIP
1080                 if (tmp & (SL_MODE_CSLIP|SL_MODE_ADAPTIVE))
1081                         return -EINVAL;
1082 #else
1083                 if ((tmp & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) ==
1084                     (SL_MODE_ADAPTIVE | SL_MODE_CSLIP))
1085                         /* return -EINVAL; */
1086                         tmp &= ~SL_MODE_ADAPTIVE;
1087 #endif
1088 #ifndef CONFIG_SLIP_MODE_SLIP6
1089                 if (tmp & SL_MODE_SLIP6)
1090                         return -EINVAL;
1091 #endif
1092                 sl->mode = tmp;
1093                 sl->dev->type = ARPHRD_SLIP + sl->mode;
1094                 return 0;
1095
1096         case SIOCSIFHWADDR:
1097                 return -EINVAL;
1098
1099 #ifdef CONFIG_SLIP_SMART
1100         /* VSV changes start here */
1101         case SIOCSKEEPALIVE:
1102                 if (get_user(tmp, p))
1103                         return -EFAULT;
1104                 if (tmp > 255) /* max for unchar */
1105                         return -EINVAL;
1106
1107                 spin_lock_bh(&sl->lock);
1108                 if (!sl->tty) {
1109                         spin_unlock_bh(&sl->lock);
1110                         return -ENODEV;
1111                 }
1112                 sl->keepalive = (u8)tmp;
1113                 if (sl->keepalive != 0) {
1114                         mod_timer(&sl->keepalive_timer,
1115                                         jiffies + sl->keepalive * HZ);
1116                         set_bit(SLF_KEEPTEST, &sl->flags);
1117                 } else
1118                         del_timer(&sl->keepalive_timer);
1119                 spin_unlock_bh(&sl->lock);
1120                 return 0;
1121
1122         case SIOCGKEEPALIVE:
1123                 if (put_user(sl->keepalive, p))
1124                         return -EFAULT;
1125                 return 0;
1126
1127         case SIOCSOUTFILL:
1128                 if (get_user(tmp, p))
1129                         return -EFAULT;
1130                 if (tmp > 255) /* max for unchar */
1131                         return -EINVAL;
1132                 spin_lock_bh(&sl->lock);
1133                 if (!sl->tty) {
1134                         spin_unlock_bh(&sl->lock);
1135                         return -ENODEV;
1136                 }
1137                 sl->outfill = (u8)tmp;
1138                 if (sl->outfill != 0) {
1139                         mod_timer(&sl->outfill_timer,
1140                                                 jiffies + sl->outfill * HZ);
1141                         set_bit(SLF_OUTWAIT, &sl->flags);
1142                 } else
1143                         del_timer(&sl->outfill_timer);
1144                 spin_unlock_bh(&sl->lock);
1145                 return 0;
1146
1147         case SIOCGOUTFILL:
1148                 if (put_user(sl->outfill, p))
1149                         return -EFAULT;
1150                 return 0;
1151         /* VSV changes end */
1152 #endif
1153         default:
1154                 return tty_mode_ioctl(tty, file, cmd, arg);
1155         }
1156 }
1157
1158 #ifdef CONFIG_COMPAT
1159 static long slip_compat_ioctl(struct tty_struct *tty, struct file *file,
1160                                         unsigned int cmd, unsigned long arg)
1161 {
1162         switch (cmd) {
1163         case SIOCGIFNAME:
1164         case SIOCGIFENCAP:
1165         case SIOCSIFENCAP:
1166         case SIOCSIFHWADDR:
1167         case SIOCSKEEPALIVE:
1168         case SIOCGKEEPALIVE:
1169         case SIOCSOUTFILL:
1170         case SIOCGOUTFILL:
1171                 return slip_ioctl(tty, file, cmd,
1172                                   (unsigned long)compat_ptr(arg));
1173         }
1174
1175         return -ENOIOCTLCMD;
1176 }
1177 #endif
1178
1179 /* VSV changes start here */
1180 #ifdef CONFIG_SLIP_SMART
1181 /* function do_ioctl called from net/core/dev.c
1182    to allow get/set outfill/keepalive parameter
1183    by ifconfig                                 */
1184
1185 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
1186 {
1187         struct slip *sl = netdev_priv(dev);
1188         unsigned long *p = (unsigned long *)&rq->ifr_ifru;
1189
1190         if (sl == NULL)         /* Allocation failed ?? */
1191                 return -ENODEV;
1192
1193         spin_lock_bh(&sl->lock);
1194
1195         if (!sl->tty) {
1196                 spin_unlock_bh(&sl->lock);
1197                 return -ENODEV;
1198         }
1199
1200         switch (cmd) {
1201         case SIOCSKEEPALIVE:
1202                 /* max for unchar */
1203                 if ((unsigned)*p > 255) {
1204                         spin_unlock_bh(&sl->lock);
1205                         return -EINVAL;
1206                 }
1207                 sl->keepalive = (u8)*p;
1208                 if (sl->keepalive != 0) {
1209                         sl->keepalive_timer.expires =
1210                                                 jiffies + sl->keepalive * HZ;
1211                         mod_timer(&sl->keepalive_timer,
1212                                                 jiffies + sl->keepalive * HZ);
1213                         set_bit(SLF_KEEPTEST, &sl->flags);
1214                 } else
1215                         del_timer(&sl->keepalive_timer);
1216                 break;
1217
1218         case SIOCGKEEPALIVE:
1219                 *p = sl->keepalive;
1220                 break;
1221
1222         case SIOCSOUTFILL:
1223                 if ((unsigned)*p > 255) { /* max for unchar */
1224                         spin_unlock_bh(&sl->lock);
1225                         return -EINVAL;
1226                 }
1227                 sl->outfill = (u8)*p;
1228                 if (sl->outfill != 0) {
1229                         mod_timer(&sl->outfill_timer,
1230                                                 jiffies + sl->outfill * HZ);
1231                         set_bit(SLF_OUTWAIT, &sl->flags);
1232                 } else
1233                         del_timer(&sl->outfill_timer);
1234                 break;
1235
1236         case SIOCGOUTFILL:
1237                 *p = sl->outfill;
1238                 break;
1239
1240         case SIOCSLEASE:
1241                 /* Resolve race condition, when ioctl'ing hanged up
1242                    and opened by another process device.
1243                  */
1244                 if (sl->tty != current->signal->tty &&
1245                                                 sl->pid != current->pid) {
1246                         spin_unlock_bh(&sl->lock);
1247                         return -EPERM;
1248                 }
1249                 sl->leased = 0;
1250                 if (*p)
1251                         sl->leased = 1;
1252                 break;
1253
1254         case SIOCGLEASE:
1255                 *p = sl->leased;
1256         }
1257         spin_unlock_bh(&sl->lock);
1258         return 0;
1259 }
1260 #endif
1261 /* VSV changes end */
1262
1263 static struct tty_ldisc_ops sl_ldisc = {
1264         .owner          = THIS_MODULE,
1265         .magic          = TTY_LDISC_MAGIC,
1266         .name           = "slip",
1267         .open           = slip_open,
1268         .close          = slip_close,
1269         .hangup         = slip_hangup,
1270         .ioctl          = slip_ioctl,
1271 #ifdef CONFIG_COMPAT
1272         .compat_ioctl   = slip_compat_ioctl,
1273 #endif
1274         .receive_buf    = slip_receive_buf,
1275         .write_wakeup   = slip_write_wakeup,
1276 };
1277
1278 static int __init slip_init(void)
1279 {
1280         int status;
1281
1282         if (slip_maxdev < 4)
1283                 slip_maxdev = 4; /* Sanity */
1284
1285         printk(KERN_INFO "SLIP: version %s (dynamic channels, max=%d)"
1286 #ifdef CONFIG_SLIP_MODE_SLIP6
1287                " (6 bit encapsulation enabled)"
1288 #endif
1289                ".\n",
1290                SLIP_VERSION, slip_maxdev);
1291 #if defined(SL_INCLUDE_CSLIP)
1292         printk(KERN_INFO "CSLIP: code copyright 1989 Regents of the University of California.\n");
1293 #endif
1294 #ifdef CONFIG_SLIP_SMART
1295         printk(KERN_INFO "SLIP linefill/keepalive option.\n");
1296 #endif
1297
1298         slip_devs = kzalloc(sizeof(struct net_device *)*slip_maxdev,
1299                                                                 GFP_KERNEL);
1300         if (!slip_devs) {
1301                 printk(KERN_ERR "SLIP: Can't allocate slip devices array.\n");
1302                 return -ENOMEM;
1303         }
1304
1305         /* Fill in our line protocol discipline, and register it */
1306         status = tty_register_ldisc(N_SLIP, &sl_ldisc);
1307         if (status != 0) {
1308                 printk(KERN_ERR "SLIP: can't register line discipline (err = %d)\n", status);
1309                 kfree(slip_devs);
1310         }
1311         return status;
1312 }
1313
1314 static void __exit slip_exit(void)
1315 {
1316         int i;
1317         struct net_device *dev;
1318         struct slip *sl;
1319         unsigned long timeout = jiffies + HZ;
1320         int busy = 0;
1321
1322         if (slip_devs == NULL)
1323                 return;
1324
1325         /* First of all: check for active disciplines and hangup them.
1326          */
1327         do {
1328                 if (busy)
1329                         msleep_interruptible(100);
1330
1331                 busy = 0;
1332                 for (i = 0; i < slip_maxdev; i++) {
1333                         dev = slip_devs[i];
1334                         if (!dev)
1335                                 continue;
1336                         sl = netdev_priv(dev);
1337                         spin_lock_bh(&sl->lock);
1338                         if (sl->tty) {
1339                                 busy++;
1340                                 tty_hangup(sl->tty);
1341                         }
1342                         spin_unlock_bh(&sl->lock);
1343                 }
1344         } while (busy && time_before(jiffies, timeout));
1345
1346         /* FIXME: hangup is async so we should wait when doing this second
1347            phase */
1348
1349         for (i = 0; i < slip_maxdev; i++) {
1350                 dev = slip_devs[i];
1351                 if (!dev)
1352                         continue;
1353                 slip_devs[i] = NULL;
1354
1355                 sl = netdev_priv(dev);
1356                 if (sl->tty) {
1357                         printk(KERN_ERR "%s: tty discipline still running\n",
1358                                dev->name);
1359                         /* Intentionally leak the control block. */
1360                         dev->destructor = NULL;
1361                 }
1362
1363                 unregister_netdev(dev);
1364         }
1365
1366         kfree(slip_devs);
1367         slip_devs = NULL;
1368
1369         i = tty_unregister_ldisc(N_SLIP);
1370         if (i != 0)
1371                 printk(KERN_ERR "SLIP: can't unregister line discipline (err = %d)\n", i);
1372 }
1373
1374 module_init(slip_init);
1375 module_exit(slip_exit);
1376
1377 #ifdef CONFIG_SLIP_SMART
1378 /*
1379  * This is start of the code for multislip style line checking
1380  * added by Stanislav Voronyi. All changes before marked VSV
1381  */
1382
1383 static void sl_outfill(unsigned long sls)
1384 {
1385         struct slip *sl = (struct slip *)sls;
1386
1387         spin_lock(&sl->lock);
1388
1389         if (sl->tty == NULL)
1390                 goto out;
1391
1392         if (sl->outfill) {
1393                 if (test_bit(SLF_OUTWAIT, &sl->flags)) {
1394                         /* no packets were transmitted, do outfill */
1395 #ifdef CONFIG_SLIP_MODE_SLIP6
1396                         unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END;
1397 #else
1398                         unsigned char s = END;
1399 #endif
1400                         /* put END into tty queue. Is it right ??? */
1401                         if (!netif_queue_stopped(sl->dev)) {
1402                                 /* if device busy no outfill */
1403                                 sl->tty->ops->write(sl->tty, &s, 1);
1404                         }
1405                 } else
1406                         set_bit(SLF_OUTWAIT, &sl->flags);
1407
1408                 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
1409         }
1410 out:
1411         spin_unlock(&sl->lock);
1412 }
1413
1414 static void sl_keepalive(unsigned long sls)
1415 {
1416         struct slip *sl = (struct slip *)sls;
1417
1418         spin_lock(&sl->lock);
1419
1420         if (sl->tty == NULL)
1421                 goto out;
1422
1423         if (sl->keepalive) {
1424                 if (test_bit(SLF_KEEPTEST, &sl->flags)) {
1425                         /* keepalive still high :(, we must hangup */
1426                         if (sl->outfill)
1427                                 /* outfill timer must be deleted too */
1428                                 (void)del_timer(&sl->outfill_timer);
1429                         printk(KERN_DEBUG "%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name);
1430                         /* this must hangup tty & close slip */
1431                         tty_hangup(sl->tty);
1432                         /* I think we need not something else */
1433                         goto out;
1434                 } else
1435                         set_bit(SLF_KEEPTEST, &sl->flags);
1436
1437                 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
1438         }
1439 out:
1440         spin_unlock(&sl->lock);
1441 }
1442
1443 #endif
1444 MODULE_LICENSE("GPL");
1445 MODULE_ALIAS_LDISC(N_SLIP);