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 <linux/uaccess.h>
  68 #include <linux/bitops.h>
  69 #include <linux/sched/signal.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 <linux/workqueue.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 (IS_ERR(slcomp))
 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         skb_put_data(skb, sl->rbuff, count);
 368         skb_reset_mac_header(skb);
 369         skb->protocol = htons(ETH_P_IP);
 370         netif_rx_ni(skb);
 371         dev->stats.rx_packets++;
 372 }
 373
 374 /* Encapsulate one IP datagram and stuff into a TTY queue. */
 375 static void sl_encaps(struct slip *sl, unsigned char *icp, int len)
 376 {
 377         unsigned char *p;
 378         int actual, count;
 379
 380         if (len > sl->mtu) {            /* Sigh, shouldn't occur BUT ... */
 381                 printk(KERN_WARNING "%s: truncating oversized transmit packet!\n", sl->dev->name);
 382                 sl->dev->stats.tx_dropped++;
 383                 sl_unlock(sl);
 384                 return;
 385         }
 386
 387         p = icp;
 388 #ifdef SL_INCLUDE_CSLIP
 389         if (sl->mode & SL_MODE_CSLIP)
 390                 len = slhc_compress(sl->slcomp, p, len, sl->cbuff, &p, 1);
 391 #endif
 392 #ifdef CONFIG_SLIP_MODE_SLIP6
 393         if (sl->mode & SL_MODE_SLIP6)
 394                 count = slip_esc6(p, sl->xbuff, len);
 395         else
 396 #endif
 397                 count = slip_esc(p, 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         netif_trans_update(sl->dev);
 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 /* Write out any remaining transmit buffer. Scheduled when tty is writable */
 421 static void slip_transmit(struct work_struct *work)
 422 {
 423         struct slip *sl = container_of(work, struct slip, tx_work);
 424         int actual;
 425
 426         spin_lock_bh(&sl->lock);
 427         /* First make sure we're connected. */
 428         if (!sl->tty || sl->magic != SLIP_MAGIC || !netif_running(sl->dev)) {
 429                 spin_unlock_bh(&sl->lock);
 430                 return;
 431         }
 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, &sl->tty->flags);
 438                 spin_unlock_bh(&sl->lock);
 439                 sl_unlock(sl);
 440                 return;
 441         }
 442
 443         actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
 444         sl->xleft -= actual;
 445         sl->xhead += actual;
 446         spin_unlock_bh(&sl->lock);
 447 }
 448
 449 /*
 450  * Called by the driver when there's room for more data.
 451  * Schedule the transmit.
 452  */
 453 static void slip_write_wakeup(struct tty_struct *tty)
 454 {
 455         struct slip *sl;
 456
 457         rcu_read_lock();
 458         sl = rcu_dereference(tty->disc_data);
 459         if (!sl)
 460                 goto out;
 461
 462         schedule_work(&sl->tx_work);
 463 out:
 464         rcu_read_unlock();
 465 }
 466
 467 static void sl_tx_timeout(struct net_device *dev)
 468 {
 469         struct slip *sl = netdev_priv(dev);
 470
 471         spin_lock(&sl->lock);
 472
 473         if (netif_queue_stopped(dev)) {
 474                 if (!netif_running(dev) || !sl->tty)
 475                         goto out;
 476
 477                 /* May be we must check transmitter timeout here ?
 478                  *      14 Oct 1994 Dmitry Gorodchanin.
 479                  */
 480 #ifdef SL_CHECK_TRANSMIT
 481                 if (time_before(jiffies, dev_trans_start(dev) + 20 * HZ))  {
 482                         /* 20 sec timeout not reached */
 483                         goto out;
 484                 }
 485                 printk(KERN_WARNING "%s: transmit timed out, %s?\n",
 486                         dev->name,
 487                         (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
 488                                 "bad line quality" : "driver error");
 489                 sl->xleft = 0;
 490                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 491                 sl_unlock(sl);
 492 #endif
 493         }
 494 out:
 495         spin_unlock(&sl->lock);
 496 }
 497
 498
 499 /* Encapsulate an IP datagram and kick it into a TTY queue. */
 500 static netdev_tx_t
 501 sl_xmit(struct sk_buff *skb, struct net_device *dev)
 502 {
 503         struct slip *sl = netdev_priv(dev);
 504
 505         spin_lock(&sl->lock);
 506         if (!netif_running(dev)) {
 507                 spin_unlock(&sl->lock);
 508                 printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name);
 509                 dev_kfree_skb(skb);
 510                 return NETDEV_TX_OK;
 511         }
 512         if (sl->tty == NULL) {
 513                 spin_unlock(&sl->lock);
 514                 dev_kfree_skb(skb);
 515                 return NETDEV_TX_OK;
 516         }
 517
 518         sl_lock(sl);
 519         dev->stats.tx_bytes += skb->len;
 520         sl_encaps(sl, skb->data, skb->len);
 521         spin_unlock(&sl->lock);
 522
 523         dev_kfree_skb(skb);
 524         return NETDEV_TX_OK;
 525 }
 526
 527
 528 /******************************************
 529  *   Routines looking at netdevice side.
 530  ******************************************/
 531
 532 /* Netdevice UP -> DOWN routine */
 533
 534 static int
 535 sl_close(struct net_device *dev)
 536 {
 537         struct slip *sl = netdev_priv(dev);
 538
 539         spin_lock_bh(&sl->lock);
 540         if (sl->tty)
 541                 /* TTY discipline is running. */
 542                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 543         netif_stop_queue(dev);
 544         sl->rcount   = 0;
 545         sl->xleft    = 0;
 546         spin_unlock_bh(&sl->lock);
 547
 548         return 0;
 549 }
 550
 551 /* Netdevice DOWN -> UP routine */
 552
 553 static int sl_open(struct net_device *dev)
 554 {
 555         struct slip *sl = netdev_priv(dev);
 556
 557         if (sl->tty == NULL)
 558                 return -ENODEV;
 559
 560         sl->flags &= (1 << SLF_INUSE);
 561         netif_start_queue(dev);
 562         return 0;
 563 }
 564
 565 /* Netdevice change MTU request */
 566
 567 static int sl_change_mtu(struct net_device *dev, int new_mtu)
 568 {
 569         struct slip *sl = netdev_priv(dev);
 570
 571         return sl_realloc_bufs(sl, new_mtu);
 572 }
 573
 574 /* Netdevice get statistics request */
 575
 576 static void
 577 sl_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
 578 {
 579         struct net_device_stats *devstats = &dev->stats;
 580 #ifdef SL_INCLUDE_CSLIP
 581         struct slip *sl = netdev_priv(dev);
 582         struct slcompress *comp = sl->slcomp;
 583 #endif
 584         stats->rx_packets     = devstats->rx_packets;
 585         stats->tx_packets     = devstats->tx_packets;
 586         stats->rx_bytes       = devstats->rx_bytes;
 587         stats->tx_bytes       = devstats->tx_bytes;
 588         stats->rx_dropped     = devstats->rx_dropped;
 589         stats->tx_dropped     = devstats->tx_dropped;
 590         stats->tx_errors      = devstats->tx_errors;
 591         stats->rx_errors      = devstats->rx_errors;
 592         stats->rx_over_errors = devstats->rx_over_errors;
 593
 594 #ifdef SL_INCLUDE_CSLIP
 595         if (comp) {
 596                 /* Generic compressed statistics */
 597                 stats->rx_compressed   = comp->sls_i_compressed;
 598                 stats->tx_compressed   = comp->sls_o_compressed;
 599
 600                 /* Are we really still needs this? */
 601                 stats->rx_fifo_errors += comp->sls_i_compressed;
 602                 stats->rx_dropped     += comp->sls_i_tossed;
 603                 stats->tx_fifo_errors += comp->sls_o_compressed;
 604                 stats->collisions     += comp->sls_o_misses;
 605         }
 606 #endif
 607 }
 608
 609 /* Netdevice register callback */
 610
 611 static int sl_init(struct net_device *dev)
 612 {
 613         struct slip *sl = netdev_priv(dev);
 614
 615         /*
 616          *      Finish setting up the DEVICE info.
 617          */
 618
 619         dev->mtu                = sl->mtu;
 620         dev->type               = ARPHRD_SLIP + sl->mode;
 621 #ifdef SL_CHECK_TRANSMIT
 622         dev->watchdog_timeo     = 20*HZ;
 623 #endif
 624         return 0;
 625 }
 626
 627
 628 static void sl_uninit(struct net_device *dev)
 629 {
 630         struct slip *sl = netdev_priv(dev);
 631
 632         sl_free_bufs(sl);
 633 }
 634
 635 /* Hook the destructor so we can free slip devices at the right point in time */
 636 static void sl_free_netdev(struct net_device *dev)
 637 {
 638         int i = dev->base_addr;
 639
 640         slip_devs[i] = NULL;
 641 }
 642
 643 static const struct net_device_ops sl_netdev_ops = {
 644         .ndo_init               = sl_init,
 645         .ndo_uninit             = sl_uninit,
 646         .ndo_open               = sl_open,
 647         .ndo_stop               = sl_close,
 648         .ndo_start_xmit         = sl_xmit,
 649         .ndo_get_stats64        = sl_get_stats64,
 650         .ndo_change_mtu         = sl_change_mtu,
 651         .ndo_tx_timeout         = sl_tx_timeout,
 652 #ifdef CONFIG_SLIP_SMART
 653         .ndo_do_ioctl           = sl_ioctl,
 654 #endif
 655 };
 656
 657
 658 static void sl_setup(struct net_device *dev)
 659 {
 660         dev->netdev_ops         = &sl_netdev_ops;
 661         dev->needs_free_netdev  = true;
 662         dev->priv_destructor    = sl_free_netdev;
 663
 664         dev->hard_header_len    = 0;
 665         dev->addr_len           = 0;
 666         dev->tx_queue_len       = 10;
 667
 668         /* MTU range: 68 - 65534 */
 669         dev->min_mtu = 68;
 670         dev->max_mtu = 65534;
 671
 672         /* New-style flags. */
 673         dev->flags              = IFF_NOARP|IFF_POINTOPOINT|IFF_MULTICAST;
 674 }
 675
 676 /******************************************
 677   Routines looking at TTY side.
 678  ******************************************/
 679
 680
 681 /*
 682  * Handle the 'receiver data ready' interrupt.
 683  * This function is called by the 'tty_io' module in the kernel when
 684  * a block of SLIP data has been received, which can now be decapsulated
 685  * and sent on to some IP layer for further processing. This will not
 686  * be re-entered while running but other ldisc functions may be called
 687  * in parallel
 688  */
 689
 690 static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 691                                                         char *fp, int count)
 692 {
 693         struct slip *sl = tty->disc_data;
 694
 695         if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
 696                 return;
 697
 698         /* Read the characters out of the buffer */
 699         while (count--) {
 700                 if (fp && *fp++) {
 701                         if (!test_and_set_bit(SLF_ERROR, &sl->flags))
 702                                 sl->dev->stats.rx_errors++;
 703                         cp++;
 704                         continue;
 705                 }
 706 #ifdef CONFIG_SLIP_MODE_SLIP6
 707                 if (sl->mode & SL_MODE_SLIP6)
 708                         slip_unesc6(sl, *cp++);
 709                 else
 710 #endif
 711                         slip_unesc(sl, *cp++);
 712         }
 713 }
 714
 715 /************************************
 716  *  slip_open helper routines.
 717  ************************************/
 718
 719 /* Collect hanged up channels */
 720 static void sl_sync(void)
 721 {
 722         int i;
 723         struct net_device *dev;
 724         struct slip       *sl;
 725
 726         for (i = 0; i < slip_maxdev; i++) {
 727                 dev = slip_devs[i];
 728                 if (dev == NULL)
 729                         break;
 730
 731                 sl = netdev_priv(dev);
 732                 if (sl->tty || sl->leased)
 733                         continue;
 734                 if (dev->flags & IFF_UP)
 735                         dev_close(dev);
 736         }
 737 }
 738
 739
 740 /* Find a free SLIP channel, and link in this `tty' line. */
 741 static struct slip *sl_alloc(dev_t line)
 742 {
 743         int i;
 744         char name[IFNAMSIZ];
 745         struct net_device *dev = NULL;
 746         struct slip       *sl;
 747
 748         for (i = 0; i < slip_maxdev; i++) {
 749                 dev = slip_devs[i];
 750                 if (dev == NULL)
 751                         break;
 752         }
 753         /* Sorry, too many, all slots in use */
 754         if (i >= slip_maxdev)
 755                 return NULL;
 756
 757         sprintf(name, "sl%d", i);
 758         dev = alloc_netdev(sizeof(*sl), name, NET_NAME_UNKNOWN, sl_setup);
 759         if (!dev)
 760                 return NULL;
 761
 762         dev->base_addr  = i;
 763         sl = netdev_priv(dev);
 764
 765         /* Initialize channel control data */
 766         sl->magic       = SLIP_MAGIC;
 767         sl->dev         = dev;
 768         spin_lock_init(&sl->lock);
 769         INIT_WORK(&sl->tx_work, slip_transmit);
 770         sl->mode        = SL_MODE_DEFAULT;
 771 #ifdef CONFIG_SLIP_SMART
 772         /* initialize timer_list struct */
 773         init_timer(&sl->keepalive_timer);
 774         sl->keepalive_timer.data = (unsigned long)sl;
 775         sl->keepalive_timer.function = sl_keepalive;
 776         init_timer(&sl->outfill_timer);
 777         sl->outfill_timer.data = (unsigned long)sl;
 778         sl->outfill_timer.function = sl_outfill;
 779 #endif
 780         slip_devs[i] = dev;
 781         return sl;
 782 }
 783
 784 /*
 785  * Open the high-level part of the SLIP channel.
 786  * This function is called by the TTY module when the
 787  * SLIP line discipline is called for.  Because we are
 788  * sure the tty line exists, we only have to link it to
 789  * a free SLIP channel...
 790  *
 791  * Called in process context serialized from other ldisc calls.
 792  */
 793
 794 static int slip_open(struct tty_struct *tty)
 795 {
 796         struct slip *sl;
 797         int err;
 798
 799         if (!capable(CAP_NET_ADMIN))
 800                 return -EPERM;
 801
 802         if (tty->ops->write == NULL)
 803                 return -EOPNOTSUPP;
 804
 805         /* RTnetlink lock is misused here to serialize concurrent
 806            opens of slip channels. There are better ways, but it is
 807            the simplest one.
 808          */
 809         rtnl_lock();
 810
 811         /* Collect hanged up channels. */
 812         sl_sync();
 813
 814         sl = tty->disc_data;
 815
 816         err = -EEXIST;
 817         /* First make sure we're not already connected. */
 818         if (sl && sl->magic == SLIP_MAGIC)
 819                 goto err_exit;
 820
 821         /* OK.  Find a free SLIP channel to use. */
 822         err = -ENFILE;
 823         sl = sl_alloc(tty_devnum(tty));
 824         if (sl == NULL)
 825                 goto err_exit;
 826
 827         sl->tty = tty;
 828         tty->disc_data = sl;
 829         sl->pid = current->pid;
 830
 831         if (!test_bit(SLF_INUSE, &sl->flags)) {
 832                 /* Perform the low-level SLIP initialization. */
 833                 err = sl_alloc_bufs(sl, SL_MTU);
 834                 if (err)
 835                         goto err_free_chan;
 836
 837                 set_bit(SLF_INUSE, &sl->flags);
 838
 839                 err = register_netdevice(sl->dev);
 840                 if (err)
 841                         goto err_free_bufs;
 842         }
 843
 844 #ifdef CONFIG_SLIP_SMART
 845         if (sl->keepalive) {
 846                 sl->keepalive_timer.expires = jiffies + sl->keepalive * HZ;
 847                 add_timer(&sl->keepalive_timer);
 848         }
 849         if (sl->outfill) {
 850                 sl->outfill_timer.expires = jiffies + sl->outfill * HZ;
 851                 add_timer(&sl->outfill_timer);
 852         }
 853 #endif
 854
 855         /* Done.  We have linked the TTY line to a channel. */
 856         rtnl_unlock();
 857         tty->receive_room = 65536;      /* We don't flow control */
 858
 859         /* TTY layer expects 0 on success */
 860         return 0;
 861
 862 err_free_bufs:
 863         sl_free_bufs(sl);
 864
 865 err_free_chan:
 866         sl->tty = NULL;
 867         tty->disc_data = NULL;
 868         clear_bit(SLF_INUSE, &sl->flags);
 869         sl_free_netdev(sl->dev);
 870         /* do not call free_netdev before rtnl_unlock */
 871         rtnl_unlock();
 872         free_netdev(sl->dev);
 873         return err;
 874
 875 err_exit:
 876         rtnl_unlock();
 877
 878         /* Count references from TTY module */
 879         return err;
 880 }
 881
 882 /*
 883  * Close down a SLIP channel.
 884  * This means flushing out any pending queues, and then returning. This
 885  * call is serialized against other ldisc functions.
 886  *
 887  * We also use this method fo a hangup event
 888  */
 889
 890 static void slip_close(struct tty_struct *tty)
 891 {
 892         struct slip *sl = tty->disc_data;
 893
 894         /* First make sure we're connected. */
 895         if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty)
 896                 return;
 897
 898         spin_lock_bh(&sl->lock);
 899         rcu_assign_pointer(tty->disc_data, NULL);
 900         sl->tty = NULL;
 901         spin_unlock_bh(&sl->lock);
 902
 903         synchronize_rcu();
 904         flush_work(&sl->tx_work);
 905
 906         /* VSV = very important to remove timers */
 907 #ifdef CONFIG_SLIP_SMART
 908         del_timer_sync(&sl->keepalive_timer);
 909         del_timer_sync(&sl->outfill_timer);
 910 #endif
 911         /* Flush network side */
 912         unregister_netdev(sl->dev);
 913         /* This will complete via sl_free_netdev */
 914 }
 915
 916 static int slip_hangup(struct tty_struct *tty)
 917 {
 918         slip_close(tty);
 919         return 0;
 920 }
 921  /************************************************************************
 922   *                     STANDARD SLIP ENCAPSULATION                      *
 923   ************************************************************************/
 924
 925 static int slip_esc(unsigned char *s, unsigned char *d, int len)
 926 {
 927         unsigned char *ptr = d;
 928         unsigned char c;
 929
 930         /*
 931          * Send an initial END character to flush out any
 932          * data that may have accumulated in the receiver
 933          * due to line noise.
 934          */
 935
 936         *ptr++ = END;
 937
 938         /*
 939          * For each byte in the packet, send the appropriate
 940          * character sequence, according to the SLIP protocol.
 941          */
 942
 943         while (len-- > 0) {
 944                 switch (c = *s++) {
 945                 case END:
 946                         *ptr++ = ESC;
 947                         *ptr++ = ESC_END;
 948                         break;
 949                 case ESC:
 950                         *ptr++ = ESC;
 951                         *ptr++ = ESC_ESC;
 952                         break;
 953                 default:
 954                         *ptr++ = c;
 955                         break;
 956                 }
 957         }
 958         *ptr++ = END;
 959         return ptr - d;
 960 }
 961
 962 static void slip_unesc(struct slip *sl, unsigned char s)
 963 {
 964
 965         switch (s) {
 966         case END:
 967 #ifdef CONFIG_SLIP_SMART
 968                 /* drop keeptest bit = VSV */
 969                 if (test_bit(SLF_KEEPTEST, &sl->flags))
 970                         clear_bit(SLF_KEEPTEST, &sl->flags);
 971 #endif
 972
 973                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
 974                     (sl->rcount > 2))
 975                         sl_bump(sl);
 976                 clear_bit(SLF_ESCAPE, &sl->flags);
 977                 sl->rcount = 0;
 978                 return;
 979
 980         case ESC:
 981                 set_bit(SLF_ESCAPE, &sl->flags);
 982                 return;
 983         case ESC_ESC:
 984                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 985                         s = ESC;
 986                 break;
 987         case ESC_END:
 988                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 989                         s = END;
 990                 break;
 991         }
 992         if (!test_bit(SLF_ERROR, &sl->flags))  {
 993                 if (sl->rcount < sl->buffsize)  {
 994                         sl->rbuff[sl->rcount++] = s;
 995                         return;
 996                 }
 997                 sl->dev->stats.rx_over_errors++;
 998                 set_bit(SLF_ERROR, &sl->flags);
 999         }
1000 }
1001
1002
1003 #ifdef CONFIG_SLIP_MODE_SLIP6
1004 /************************************************************************
1005  *                       6 BIT SLIP ENCAPSULATION                       *
1006  ************************************************************************/
1007
1008 static int slip_esc6(unsigned char *s, unsigned char *d, int len)
1009 {
1010         unsigned char *ptr = d;
1011         unsigned char c;
1012         int i;
1013         unsigned short v = 0;
1014         short bits = 0;
1015
1016         /*
1017          * Send an initial END character to flush out any
1018          * data that may have accumulated in the receiver
1019          * due to line noise.
1020          */
1021
1022         *ptr++ = 0x70;
1023
1024         /*
1025          * Encode the packet into printable ascii characters
1026          */
1027
1028         for (i = 0; i < len; ++i) {
1029                 v = (v << 8) | s[i];
1030                 bits += 8;
1031                 while (bits >= 6) {
1032                         bits -= 6;
1033                         c = 0x30 + ((v >> bits) & 0x3F);
1034                         *ptr++ = c;
1035                 }
1036         }
1037         if (bits) {
1038                 c = 0x30 + ((v << (6 - bits)) & 0x3F);
1039                 *ptr++ = c;
1040         }
1041         *ptr++ = 0x70;
1042         return ptr - d;
1043 }
1044
1045 static void slip_unesc6(struct slip *sl, unsigned char s)
1046 {
1047         unsigned char c;
1048
1049         if (s == 0x70) {
1050 #ifdef CONFIG_SLIP_SMART
1051                 /* drop keeptest bit = VSV */
1052                 if (test_bit(SLF_KEEPTEST, &sl->flags))
1053                         clear_bit(SLF_KEEPTEST, &sl->flags);
1054 #endif
1055
1056                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
1057                     (sl->rcount > 2))
1058                         sl_bump(sl);
1059                 sl->rcount = 0;
1060                 sl->xbits = 0;
1061                 sl->xdata = 0;
1062         } else if (s >= 0x30 && s < 0x70) {
1063                 sl->xdata = (sl->xdata << 6) | ((s - 0x30) & 0x3F);
1064                 sl->xbits += 6;
1065                 if (sl->xbits >= 8) {
1066                         sl->xbits -= 8;
1067                         c = (unsigned char)(sl->xdata >> sl->xbits);
1068                         if (!test_bit(SLF_ERROR, &sl->flags))  {
1069                                 if (sl->rcount < sl->buffsize)  {
1070                                         sl->rbuff[sl->rcount++] = c;
1071                                         return;
1072                                 }
1073                                 sl->dev->stats.rx_over_errors++;
1074                                 set_bit(SLF_ERROR, &sl->flags);
1075                         }
1076                 }
1077         }
1078 }
1079 #endif /* CONFIG_SLIP_MODE_SLIP6 */
1080
1081 /* Perform I/O control on an active SLIP channel. */
1082 static int slip_ioctl(struct tty_struct *tty, struct file *file,
1083                                         unsigned int cmd, unsigned long arg)
1084 {
1085         struct slip *sl = tty->disc_data;
1086         unsigned int tmp;
1087         int __user *p = (int __user *)arg;
1088
1089         /* First make sure we're connected. */
1090         if (!sl || sl->magic != SLIP_MAGIC)
1091                 return -EINVAL;
1092
1093         switch (cmd) {
1094         case SIOCGIFNAME:
1095                 tmp = strlen(sl->dev->name) + 1;
1096                 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
1097                         return -EFAULT;
1098                 return 0;
1099
1100         case SIOCGIFENCAP:
1101                 if (put_user(sl->mode, p))
1102                         return -EFAULT;
1103                 return 0;
1104
1105         case SIOCSIFENCAP:
1106                 if (get_user(tmp, p))
1107                         return -EFAULT;
1108 #ifndef SL_INCLUDE_CSLIP
1109                 if (tmp & (SL_MODE_CSLIP|SL_MODE_ADAPTIVE))
1110                         return -EINVAL;
1111 #else
1112                 if ((tmp & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) ==
1113                     (SL_MODE_ADAPTIVE | SL_MODE_CSLIP))
1114                         /* return -EINVAL; */
1115                         tmp &= ~SL_MODE_ADAPTIVE;
1116 #endif
1117 #ifndef CONFIG_SLIP_MODE_SLIP6
1118                 if (tmp & SL_MODE_SLIP6)
1119                         return -EINVAL;
1120 #endif
1121                 sl->mode = tmp;
1122                 sl->dev->type = ARPHRD_SLIP + sl->mode;
1123                 return 0;
1124
1125         case SIOCSIFHWADDR:
1126                 return -EINVAL;
1127
1128 #ifdef CONFIG_SLIP_SMART
1129         /* VSV changes start here */
1130         case SIOCSKEEPALIVE:
1131                 if (get_user(tmp, p))
1132                         return -EFAULT;
1133                 if (tmp > 255) /* max for unchar */
1134                         return -EINVAL;
1135
1136                 spin_lock_bh(&sl->lock);
1137                 if (!sl->tty) {
1138                         spin_unlock_bh(&sl->lock);
1139                         return -ENODEV;
1140                 }
1141                 sl->keepalive = (u8)tmp;
1142                 if (sl->keepalive != 0) {
1143                         mod_timer(&sl->keepalive_timer,
1144                                         jiffies + sl->keepalive * HZ);
1145                         set_bit(SLF_KEEPTEST, &sl->flags);
1146                 } else
1147                         del_timer(&sl->keepalive_timer);
1148                 spin_unlock_bh(&sl->lock);
1149                 return 0;
1150
1151         case SIOCGKEEPALIVE:
1152                 if (put_user(sl->keepalive, p))
1153                         return -EFAULT;
1154                 return 0;
1155
1156         case SIOCSOUTFILL:
1157                 if (get_user(tmp, p))
1158                         return -EFAULT;
1159                 if (tmp > 255) /* max for unchar */
1160                         return -EINVAL;
1161                 spin_lock_bh(&sl->lock);
1162                 if (!sl->tty) {
1163                         spin_unlock_bh(&sl->lock);
1164                         return -ENODEV;
1165                 }
1166                 sl->outfill = (u8)tmp;
1167                 if (sl->outfill != 0) {
1168                         mod_timer(&sl->outfill_timer,
1169                                                 jiffies + sl->outfill * HZ);
1170                         set_bit(SLF_OUTWAIT, &sl->flags);
1171                 } else
1172                         del_timer(&sl->outfill_timer);
1173                 spin_unlock_bh(&sl->lock);
1174                 return 0;
1175
1176         case SIOCGOUTFILL:
1177                 if (put_user(sl->outfill, p))
1178                         return -EFAULT;
1179                 return 0;
1180         /* VSV changes end */
1181 #endif
1182         default:
1183                 return tty_mode_ioctl(tty, file, cmd, arg);
1184         }
1185 }
1186
1187 #ifdef CONFIG_COMPAT
1188 static long slip_compat_ioctl(struct tty_struct *tty, struct file *file,
1189                                         unsigned int cmd, unsigned long arg)
1190 {
1191         switch (cmd) {
1192         case SIOCGIFNAME:
1193         case SIOCGIFENCAP:
1194         case SIOCSIFENCAP:
1195         case SIOCSIFHWADDR:
1196         case SIOCSKEEPALIVE:
1197         case SIOCGKEEPALIVE:
1198         case SIOCSOUTFILL:
1199         case SIOCGOUTFILL:
1200                 return slip_ioctl(tty, file, cmd,
1201                                   (unsigned long)compat_ptr(arg));
1202         }
1203
1204         return -ENOIOCTLCMD;
1205 }
1206 #endif
1207
1208 /* VSV changes start here */
1209 #ifdef CONFIG_SLIP_SMART
1210 /* function do_ioctl called from net/core/dev.c
1211    to allow get/set outfill/keepalive parameter
1212    by ifconfig                                 */
1213
1214 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
1215 {
1216         struct slip *sl = netdev_priv(dev);
1217         unsigned long *p = (unsigned long *)&rq->ifr_ifru;
1218
1219         if (sl == NULL)         /* Allocation failed ?? */
1220                 return -ENODEV;
1221
1222         spin_lock_bh(&sl->lock);
1223
1224         if (!sl->tty) {
1225                 spin_unlock_bh(&sl->lock);
1226                 return -ENODEV;
1227         }
1228
1229         switch (cmd) {
1230         case SIOCSKEEPALIVE:
1231                 /* max for unchar */
1232                 if ((unsigned)*p > 255) {
1233                         spin_unlock_bh(&sl->lock);
1234                         return -EINVAL;
1235                 }
1236                 sl->keepalive = (u8)*p;
1237                 if (sl->keepalive != 0) {
1238                         sl->keepalive_timer.expires =
1239                                                 jiffies + sl->keepalive * HZ;
1240                         mod_timer(&sl->keepalive_timer,
1241                                                 jiffies + sl->keepalive * HZ);
1242                         set_bit(SLF_KEEPTEST, &sl->flags);
1243                 } else
1244                         del_timer(&sl->keepalive_timer);
1245                 break;
1246
1247         case SIOCGKEEPALIVE:
1248                 *p = sl->keepalive;
1249                 break;
1250
1251         case SIOCSOUTFILL:
1252                 if ((unsigned)*p > 255) { /* max for unchar */
1253                         spin_unlock_bh(&sl->lock);
1254                         return -EINVAL;
1255                 }
1256                 sl->outfill = (u8)*p;
1257                 if (sl->outfill != 0) {
1258                         mod_timer(&sl->outfill_timer,
1259                                                 jiffies + sl->outfill * HZ);
1260                         set_bit(SLF_OUTWAIT, &sl->flags);
1261                 } else
1262                         del_timer(&sl->outfill_timer);
1263                 break;
1264
1265         case SIOCGOUTFILL:
1266                 *p = sl->outfill;
1267                 break;
1268
1269         case SIOCSLEASE:
1270                 /* Resolve race condition, when ioctl'ing hanged up
1271                    and opened by another process device.
1272                  */
1273                 if (sl->tty != current->signal->tty &&
1274                                                 sl->pid != current->pid) {
1275                         spin_unlock_bh(&sl->lock);
1276                         return -EPERM;
1277                 }
1278                 sl->leased = 0;
1279                 if (*p)
1280                         sl->leased = 1;
1281                 break;
1282
1283         case SIOCGLEASE:
1284                 *p = sl->leased;
1285         }
1286         spin_unlock_bh(&sl->lock);
1287         return 0;
1288 }
1289 #endif
1290 /* VSV changes end */
1291
1292 static struct tty_ldisc_ops sl_ldisc = {
1293         .owner          = THIS_MODULE,
1294         .magic          = TTY_LDISC_MAGIC,
1295         .name           = "slip",
1296         .open           = slip_open,
1297         .close          = slip_close,
1298         .hangup         = slip_hangup,
1299         .ioctl          = slip_ioctl,
1300 #ifdef CONFIG_COMPAT
1301         .compat_ioctl   = slip_compat_ioctl,
1302 #endif
1303         .receive_buf    = slip_receive_buf,
1304         .write_wakeup   = slip_write_wakeup,
1305 };
1306
1307 static int __init slip_init(void)
1308 {
1309         int status;
1310
1311         if (slip_maxdev < 4)
1312                 slip_maxdev = 4; /* Sanity */
1313
1314         printk(KERN_INFO "SLIP: version %s (dynamic channels, max=%d)"
1315 #ifdef CONFIG_SLIP_MODE_SLIP6
1316                " (6 bit encapsulation enabled)"
1317 #endif
1318                ".\n",
1319                SLIP_VERSION, slip_maxdev);
1320 #if defined(SL_INCLUDE_CSLIP)
1321         printk(KERN_INFO "CSLIP: code copyright 1989 Regents of the University of California.\n");
1322 #endif
1323 #ifdef CONFIG_SLIP_SMART
1324         printk(KERN_INFO "SLIP linefill/keepalive option.\n");
1325 #endif
1326
1327         slip_devs = kzalloc(sizeof(struct net_device *)*slip_maxdev,
1328                                                                 GFP_KERNEL);
1329         if (!slip_devs)
1330                 return -ENOMEM;
1331
1332         /* Fill in our line protocol discipline, and register it */
1333         status = tty_register_ldisc(N_SLIP, &sl_ldisc);
1334         if (status != 0) {
1335                 printk(KERN_ERR "SLIP: can't register line discipline (err = %d)\n", status);
1336                 kfree(slip_devs);
1337         }
1338         return status;
1339 }
1340
1341 static void __exit slip_exit(void)
1342 {
1343         int i;
1344         struct net_device *dev;
1345         struct slip *sl;
1346         unsigned long timeout = jiffies + HZ;
1347         int busy = 0;
1348
1349         if (slip_devs == NULL)
1350                 return;
1351
1352         /* First of all: check for active disciplines and hangup them.
1353          */
1354         do {
1355                 if (busy)
1356                         msleep_interruptible(100);
1357
1358                 busy = 0;
1359                 for (i = 0; i < slip_maxdev; i++) {
1360                         dev = slip_devs[i];
1361                         if (!dev)
1362                                 continue;
1363                         sl = netdev_priv(dev);
1364                         spin_lock_bh(&sl->lock);
1365                         if (sl->tty) {
1366                                 busy++;
1367                                 tty_hangup(sl->tty);
1368                         }
1369                         spin_unlock_bh(&sl->lock);
1370                 }
1371         } while (busy && time_before(jiffies, timeout));
1372
1373         /* FIXME: hangup is async so we should wait when doing this second
1374            phase */
1375
1376         for (i = 0; i < slip_maxdev; i++) {
1377                 dev = slip_devs[i];
1378                 if (!dev)
1379                         continue;
1380                 slip_devs[i] = NULL;
1381
1382                 sl = netdev_priv(dev);
1383                 if (sl->tty) {
1384                         printk(KERN_ERR "%s: tty discipline still running\n",
1385                                dev->name);
1386                 }
1387
1388                 unregister_netdev(dev);
1389         }
1390
1391         kfree(slip_devs);
1392         slip_devs = NULL;
1393
1394         i = tty_unregister_ldisc(N_SLIP);
1395         if (i != 0)
1396                 printk(KERN_ERR "SLIP: can't unregister line discipline (err = %d)\n", i);
1397 }
1398
1399 module_init(slip_init);
1400 module_exit(slip_exit);
1401
1402 #ifdef CONFIG_SLIP_SMART
1403 /*
1404  * This is start of the code for multislip style line checking
1405  * added by Stanislav Voronyi. All changes before marked VSV
1406  */
1407
1408 static void sl_outfill(unsigned long sls)
1409 {
1410         struct slip *sl = (struct slip *)sls;
1411
1412         spin_lock(&sl->lock);
1413
1414         if (sl->tty == NULL)
1415                 goto out;
1416
1417         if (sl->outfill) {
1418                 if (test_bit(SLF_OUTWAIT, &sl->flags)) {
1419                         /* no packets were transmitted, do outfill */
1420 #ifdef CONFIG_SLIP_MODE_SLIP6
1421                         unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END;
1422 #else
1423                         unsigned char s = END;
1424 #endif
1425                         /* put END into tty queue. Is it right ??? */
1426                         if (!netif_queue_stopped(sl->dev)) {
1427                                 /* if device busy no outfill */
1428                                 sl->tty->ops->write(sl->tty, &s, 1);
1429                         }
1430                 } else
1431                         set_bit(SLF_OUTWAIT, &sl->flags);
1432
1433                 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
1434         }
1435 out:
1436         spin_unlock(&sl->lock);
1437 }
1438
1439 static void sl_keepalive(unsigned long sls)
1440 {
1441         struct slip *sl = (struct slip *)sls;
1442
1443         spin_lock(&sl->lock);
1444
1445         if (sl->tty == NULL)
1446                 goto out;
1447
1448         if (sl->keepalive) {
1449                 if (test_bit(SLF_KEEPTEST, &sl->flags)) {
1450                         /* keepalive still high :(, we must hangup */
1451                         if (sl->outfill)
1452                                 /* outfill timer must be deleted too */
1453                                 (void)del_timer(&sl->outfill_timer);
1454                         printk(KERN_DEBUG "%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name);
1455                         /* this must hangup tty & close slip */
1456                         tty_hangup(sl->tty);
1457                         /* I think we need not something else */
1458                         goto out;
1459                 } else
1460                         set_bit(SLF_KEEPTEST, &sl->flags);
1461
1462                 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
1463         }
1464 out:
1465         spin_unlock(&sl->lock);
1466 }
1467
1468 #endif
1469 MODULE_LICENSE("GPL");
1470 MODULE_ALIAS_LDISC(N_SLIP);