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