drivers/net/slip/slip.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * slip.c       This module implements the SLIP protocol for kernel-based
   4  *              devices like TTY.  It interfaces between a raw TTY, and the
   5  *              kernel's INET protocol layers.
   6  *
   7  * Version:     @(#)slip.c      0.8.3   12/24/94
   8  *
   9  * Authors:     Laurence Culhane, <loz@holmes.demon.co.uk>
  10  *              Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
  11  *
  12  * Fixes:
  13  *              Alan Cox        :       Sanity checks and avoid tx overruns.
  14  *                                      Has a new sl->mtu field.
  15  *              Alan Cox        :       Found cause of overrun. ifconfig sl0
  16  *                                      mtu upwards. Driver now spots this
  17  *                                      and grows/shrinks its buffers(hack!).
  18  *                                      Memory leak if you run out of memory
  19  *                                      setting up a slip driver fixed.
  20  *              Matt Dillon     :       Printable slip (borrowed from NET2E)
  21  *      Pauline Middelink       :       Slip driver fixes.
  22  *              Alan Cox        :       Honours the old SL_COMPRESSED flag
  23  *              Alan Cox        :       KISS AX.25 and AXUI IP support
  24  *              Michael Riepe   :       Automatic CSLIP recognition added
  25  *              Charles Hedrick :       CSLIP header length problem fix.
  26  *              Alan Cox        :       Corrected non-IP cases of the above.
  27  *              Alan Cox        :       Now uses hardware type as per FvK.
  28  *              Alan Cox        :       Default to 192.168.0.0 (RFC 1597)
  29  *              A.N.Kuznetsov   :       dev_tint() recursion fix.
  30  *      Dmitry Gorodchanin      :       SLIP memory leaks
  31  *      Dmitry Gorodchanin      :       Code cleanup. Reduce tty driver
  32  *                                      buffering from 4096 to 256 bytes.
  33  *                                      Improving SLIP response time.
  34  *                                      CONFIG_SLIP_MODE_SLIP6.
  35  *                                      ifconfig sl? up & down now works
  36  *                                      correctly.
  37  *                                      Modularization.
  38  *              Alan Cox        :       Oops - fix AX.25 buffer lengths
  39  *      Dmitry Gorodchanin      :       Even more cleanups. Preserve CSLIP
  40  *                                      statistics. Include CSLIP code only
  41  *                                      if it really needed.
  42  *              Alan Cox        :       Free slhc buffers in the right place.
  43  *              Alan Cox        :       Allow for digipeated IP over AX.25
  44  *              Matti Aarnio    :       Dynamic SLIP devices, with ideas taken
  45  *                                      from Jim Freeman's <jfree@caldera.com>
  46  *                                      dynamic PPP devices.  We do NOT kfree()
  47  *                                      device entries, just reg./unreg. them
  48  *                                      as they are needed.  We kfree() them
  49  *                                      at module cleanup.
  50  *                                      With MODULE-loading ``insmod'', user
  51  *                                      can issue parameter:  slip_maxdev=1024
  52  *                                      (Or how much he/she wants.. Default
  53  *                                      is 256)
  54  *      Stanislav Voronyi       :       Slip line checking, with ideas taken
  55  *                                      from multislip BSDI driver which was
  56  *                                      written by Igor Chechik, RELCOM Corp.
  57  *                                      Only algorithms have been ported to
  58  *                                      Linux SLIP driver.
  59  *      Vitaly E. Lavrov        :       Sane behaviour on tty hangup.
  60  *      Alexey Kuznetsov        :       Cleanup interfaces to tty & netdevice
  61  *                                      modules.
  62  */
  63
  64 #define SL_CHECK_TRANSMIT
  65 #include <linux/compat.h>
  66 #include <linux/module.h>
  67 #include <linux/moduleparam.h>
  68
  69 #include <linux/uaccess.h>
  70 #include <linux/bitops.h>
  71 #include <linux/sched/signal.h>
  72 #include <linux/string.h>
  73 #include <linux/mm.h>
  74 #include <linux/interrupt.h>
  75 #include <linux/in.h>
  76 #include <linux/tty.h>
  77 #include <linux/errno.h>
  78 #include <linux/netdevice.h>
  79 #include <linux/etherdevice.h>
  80 #include <linux/skbuff.h>
  81 #include <linux/rtnetlink.h>
  82 #include <linux/if_arp.h>
  83 #include <linux/if_slip.h>
  84 #include <linux/delay.h>
  85 #include <linux/init.h>
  86 #include <linux/slab.h>
  87 #include <linux/workqueue.h>
  88 #include "slip.h"
  89 #ifdef CONFIG_INET
  90 #include <linux/ip.h>
  91 #include <linux/tcp.h>
  92 #include <net/slhc_vj.h>
  93 #endif
  94
  95 #define SLIP_VERSION    "0.8.4-NET3.019-NEWTTY"
  96
  97 static struct net_device **slip_devs;
  98
  99 static int slip_maxdev = SL_NRUNIT;
 100 module_param(slip_maxdev, int, 0);
 101 MODULE_PARM_DESC(slip_maxdev, "Maximum number of slip devices");
 102
 103 static int slip_esc(unsigned char *p, unsigned char *d, int len);
 104 static void slip_unesc(struct slip *sl, unsigned char c);
 105 #ifdef CONFIG_SLIP_MODE_SLIP6
 106 static int slip_esc6(unsigned char *p, unsigned char *d, int len);
 107 static void slip_unesc6(struct slip *sl, unsigned char c);
 108 #endif
 109 #ifdef CONFIG_SLIP_SMART
 110 static void sl_keepalive(struct timer_list *t);
 111 static void sl_outfill(struct timer_list *t);
 112 static int sl_siocdevprivate(struct net_device *dev, struct ifreq *rq, void __user *data, int cmd);
 113 #endif
 114
 115 /********************************
 116 *  Buffer administration routines:
 117 *       sl_alloc_bufs()
 118 *       sl_free_bufs()
 119 *       sl_realloc_bufs()
 120 *
 121 * NOTE: sl_realloc_bufs != sl_free_bufs + sl_alloc_bufs, because
 122 *       sl_realloc_bufs provides strong atomicity and reallocation
 123 *       on actively running device.
 124 *********************************/
 125
 126 /*
 127    Allocate channel buffers.
 128  */
 129
 130 static int sl_alloc_bufs(struct slip *sl, int mtu)
 131 {
 132         int err = -ENOBUFS;
 133         unsigned long len;
 134         char *rbuff = NULL;
 135         char *xbuff = NULL;
 136 #ifdef SL_INCLUDE_CSLIP
 137         char *cbuff = NULL;
 138         struct slcompress *slcomp = NULL;
 139 #endif
 140
 141         /*
 142          * Allocate the SLIP frame buffers:
 143          *
 144          * rbuff        Receive buffer.
 145          * xbuff        Transmit buffer.
 146          * cbuff        Temporary compression buffer.
 147          */
 148         len = mtu * 2;
 149
 150         /*
 151          * allow for arrival of larger UDP packets, even if we say not to
 152          * also fixes a bug in which SunOS sends 512-byte packets even with
 153          * an MSS of 128
 154          */
 155         if (len < 576 * 2)
 156                 len = 576 * 2;
 157         rbuff = kmalloc(len + 4, GFP_KERNEL);
 158         if (rbuff == NULL)
 159                 goto err_exit;
 160         xbuff = kmalloc(len + 4, GFP_KERNEL);
 161         if (xbuff == NULL)
 162                 goto err_exit;
 163 #ifdef SL_INCLUDE_CSLIP
 164         cbuff = kmalloc(len + 4, GFP_KERNEL);
 165         if (cbuff == NULL)
 166                 goto err_exit;
 167         slcomp = slhc_init(16, 16);
 168         if (IS_ERR(slcomp))
 169                 goto err_exit;
 170 #endif
 171         spin_lock_bh(&sl->lock);
 172         if (sl->tty == NULL) {
 173                 spin_unlock_bh(&sl->lock);
 174                 err = -ENODEV;
 175                 goto err_exit;
 176         }
 177         sl->mtu      = mtu;
 178         sl->buffsize = len;
 179         sl->rcount   = 0;
 180         sl->xleft    = 0;
 181         rbuff = xchg(&sl->rbuff, rbuff);
 182         xbuff = xchg(&sl->xbuff, xbuff);
 183 #ifdef SL_INCLUDE_CSLIP
 184         cbuff = xchg(&sl->cbuff, cbuff);
 185         slcomp = xchg(&sl->slcomp, slcomp);
 186 #endif
 187 #ifdef CONFIG_SLIP_MODE_SLIP6
 188         sl->xdata    = 0;
 189         sl->xbits    = 0;
 190 #endif
 191         spin_unlock_bh(&sl->lock);
 192         err = 0;
 193
 194         /* Cleanup */
 195 err_exit:
 196 #ifdef SL_INCLUDE_CSLIP
 197         kfree(cbuff);
 198         slhc_free(slcomp);
 199 #endif
 200         kfree(xbuff);
 201         kfree(rbuff);
 202         return err;
 203 }
 204
 205 /* Free a SLIP channel buffers. */
 206 static void sl_free_bufs(struct slip *sl)
 207 {
 208         /* Free all SLIP frame buffers. */
 209         kfree(xchg(&sl->rbuff, NULL));
 210         kfree(xchg(&sl->xbuff, NULL));
 211 #ifdef SL_INCLUDE_CSLIP
 212         kfree(xchg(&sl->cbuff, NULL));
 213         slhc_free(xchg(&sl->slcomp, NULL));
 214 #endif
 215 }
 216
 217 /*
 218    Reallocate slip channel buffers.
 219  */
 220
 221 static int sl_realloc_bufs(struct slip *sl, int mtu)
 222 {
 223         int err = 0;
 224         struct net_device *dev = sl->dev;
 225         unsigned char *xbuff, *rbuff;
 226 #ifdef SL_INCLUDE_CSLIP
 227         unsigned char *cbuff;
 228 #endif
 229         int len = mtu * 2;
 230
 231 /*
 232  * allow for arrival of larger UDP packets, even if we say not to
 233  * also fixes a bug in which SunOS sends 512-byte packets even with
 234  * an MSS of 128
 235  */
 236         if (len < 576 * 2)
 237                 len = 576 * 2;
 238
 239         xbuff = kmalloc(len + 4, GFP_ATOMIC);
 240         rbuff = kmalloc(len + 4, GFP_ATOMIC);
 241 #ifdef SL_INCLUDE_CSLIP
 242         cbuff = kmalloc(len + 4, GFP_ATOMIC);
 243 #endif
 244
 245
 246 #ifdef SL_INCLUDE_CSLIP
 247         if (xbuff == NULL || rbuff == NULL || cbuff == NULL)  {
 248 #else
 249         if (xbuff == NULL || rbuff == NULL)  {
 250 #endif
 251                 if (mtu > sl->mtu) {
 252                         printk(KERN_WARNING "%s: unable to grow slip buffers, MTU change cancelled.\n",
 253                                dev->name);
 254                         err = -ENOBUFS;
 255                 }
 256                 goto done;
 257         }
 258         spin_lock_bh(&sl->lock);
 259
 260         err = -ENODEV;
 261         if (sl->tty == NULL)
 262                 goto done_on_bh;
 263
 264         xbuff    = xchg(&sl->xbuff, xbuff);
 265         rbuff    = xchg(&sl->rbuff, rbuff);
 266 #ifdef SL_INCLUDE_CSLIP
 267         cbuff    = xchg(&sl->cbuff, cbuff);
 268 #endif
 269         if (sl->xleft)  {
 270                 if (sl->xleft <= len)  {
 271                         memcpy(sl->xbuff, sl->xhead, sl->xleft);
 272                 } else  {
 273                         sl->xleft = 0;
 274                         dev->stats.tx_dropped++;
 275                 }
 276         }
 277         sl->xhead = sl->xbuff;
 278
 279         if (sl->rcount)  {
 280                 if (sl->rcount <= len) {
 281                         memcpy(sl->rbuff, rbuff, sl->rcount);
 282                 } else  {
 283                         sl->rcount = 0;
 284                         dev->stats.rx_over_errors++;
 285                         set_bit(SLF_ERROR, &sl->flags);
 286                 }
 287         }
 288         sl->mtu      = mtu;
 289         dev->mtu      = mtu;
 290         sl->buffsize = len;
 291         err = 0;
 292
 293 done_on_bh:
 294         spin_unlock_bh(&sl->lock);
 295
 296 done:
 297         kfree(xbuff);
 298         kfree(rbuff);
 299 #ifdef SL_INCLUDE_CSLIP
 300         kfree(cbuff);
 301 #endif
 302         return err;
 303 }
 304
 305
 306 /* Set the "sending" flag.  This must be atomic hence the set_bit. */
 307 static inline void sl_lock(struct slip *sl)
 308 {
 309         netif_stop_queue(sl->dev);
 310 }
 311
 312
 313 /* Clear the "sending" flag.  This must be atomic, hence the ASM. */
 314 static inline void sl_unlock(struct slip *sl)
 315 {
 316         netif_wake_queue(sl->dev);
 317 }
 318
 319 /* Send one completely decapsulated IP datagram to the IP layer. */
 320 static void sl_bump(struct slip *sl)
 321 {
 322         struct net_device *dev = sl->dev;
 323         struct sk_buff *skb;
 324         int count;
 325
 326         count = sl->rcount;
 327 #ifdef SL_INCLUDE_CSLIP
 328         if (sl->mode & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) {
 329                 unsigned char c = sl->rbuff[0];
 330                 if (c & SL_TYPE_COMPRESSED_TCP) {
 331                         /* ignore compressed packets when CSLIP is off */
 332                         if (!(sl->mode & SL_MODE_CSLIP)) {
 333                                 printk(KERN_WARNING "%s: compressed packet ignored\n", dev->name);
 334                                 return;
 335                         }
 336                         /* make sure we've reserved enough space for uncompress
 337                            to use */
 338                         if (count + 80 > sl->buffsize) {
 339                                 dev->stats.rx_over_errors++;
 340                                 return;
 341                         }
 342                         count = slhc_uncompress(sl->slcomp, sl->rbuff, count);
 343                         if (count <= 0)
 344                                 return;
 345                 } else if (c >= SL_TYPE_UNCOMPRESSED_TCP) {
 346                         if (!(sl->mode & SL_MODE_CSLIP)) {
 347                                 /* turn on header compression */
 348                                 sl->mode |= SL_MODE_CSLIP;
 349                                 sl->mode &= ~SL_MODE_ADAPTIVE;
 350                                 printk(KERN_INFO "%s: header compression turned on\n", dev->name);
 351                         }
 352                         sl->rbuff[0] &= 0x4f;
 353                         if (slhc_remember(sl->slcomp, sl->rbuff, count) <= 0)
 354                                 return;
 355                 }
 356         }
 357 #endif  /* SL_INCLUDE_CSLIP */
 358
 359         dev->stats.rx_bytes += count;
 360
 361         skb = dev_alloc_skb(count);
 362         if (skb == NULL) {
 363                 printk(KERN_WARNING "%s: memory squeeze, dropping packet.\n", dev->name);
 364                 dev->stats.rx_dropped++;
 365                 return;
 366         }
 367         skb->dev = dev;
 368         skb_put_data(skb, sl->rbuff, count);
 369         skb_reset_mac_header(skb);
 370         skb->protocol = htons(ETH_P_IP);
 371         netif_rx(skb);
 372         dev->stats.rx_packets++;
 373 }
 374
 375 /* Encapsulate one IP datagram and stuff into a TTY queue. */
 376 static void sl_encaps(struct slip *sl, unsigned char *icp, int len)
 377 {
 378         unsigned char *p;
 379         int actual, count;
 380
 381         if (len > sl->mtu) {            /* Sigh, shouldn't occur BUT ... */
 382                 printk(KERN_WARNING "%s: truncating oversized transmit packet!\n", sl->dev->name);
 383                 sl->dev->stats.tx_dropped++;
 384                 sl_unlock(sl);
 385                 return;
 386         }
 387
 388         p = icp;
 389 #ifdef SL_INCLUDE_CSLIP
 390         if (sl->mode & SL_MODE_CSLIP)
 391                 len = slhc_compress(sl->slcomp, p, len, sl->cbuff, &p, 1);
 392 #endif
 393 #ifdef CONFIG_SLIP_MODE_SLIP6
 394         if (sl->mode & SL_MODE_SLIP6)
 395                 count = slip_esc6(p, sl->xbuff, len);
 396         else
 397 #endif
 398                 count = slip_esc(p, sl->xbuff, len);
 399
 400         /* Order of next two lines is *very* important.
 401          * When we are sending a little amount of data,
 402          * the transfer may be completed inside the ops->write()
 403          * routine, because it's running with interrupts enabled.
 404          * In this case we *never* got WRITE_WAKEUP event,
 405          * if we did not request it before write operation.
 406          *       14 Oct 1994  Dmitry Gorodchanin.
 407          */
 408         set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 409         actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
 410 #ifdef SL_CHECK_TRANSMIT
 411         netif_trans_update(sl->dev);
 412 #endif
 413         sl->xleft = count - actual;
 414         sl->xhead = sl->xbuff + actual;
 415 #ifdef CONFIG_SLIP_SMART
 416         /* VSV */
 417         clear_bit(SLF_OUTWAIT, &sl->flags);     /* reset outfill flag */
 418 #endif
 419 }
 420
 421 /* Write out any remaining transmit buffer. Scheduled when tty is writable */
 422 static void slip_transmit(struct work_struct *work)
 423 {
 424         struct slip *sl = container_of(work, struct slip, tx_work);
 425         int actual;
 426
 427         spin_lock_bh(&sl->lock);
 428         /* First make sure we're connected. */
 429         if (!sl->tty || sl->magic != SLIP_MAGIC || !netif_running(sl->dev)) {
 430                 spin_unlock_bh(&sl->lock);
 431                 return;
 432         }
 433
 434         if (sl->xleft <= 0)  {
 435                 /* Now serial buffer is almost free & we can start
 436                  * transmission of another packet */
 437                 sl->dev->stats.tx_packets++;
 438                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 439                 spin_unlock_bh(&sl->lock);
 440                 sl_unlock(sl);
 441                 return;
 442         }
 443
 444         actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
 445         sl->xleft -= actual;
 446         sl->xhead += actual;
 447         spin_unlock_bh(&sl->lock);
 448 }
 449
 450 /*
 451  * Called by the driver when there's room for more data.
 452  * Schedule the transmit.
 453  */
 454 static void slip_write_wakeup(struct tty_struct *tty)
 455 {
 456         struct slip *sl;
 457
 458         rcu_read_lock();
 459         sl = rcu_dereference(tty->disc_data);
 460         if (sl)
 461                 schedule_work(&sl->tx_work);
 462         rcu_read_unlock();
 463 }
 464
 465 static void sl_tx_timeout(struct net_device *dev, unsigned int txqueue)
 466 {
 467         struct slip *sl = netdev_priv(dev);
 468
 469         spin_lock(&sl->lock);
 470
 471         if (netif_queue_stopped(dev)) {
 472                 if (!netif_running(dev))
 473                         goto out;
 474
 475                 /* May be we must check transmitter timeout here ?
 476                  *      14 Oct 1994 Dmitry Gorodchanin.
 477                  */
 478 #ifdef SL_CHECK_TRANSMIT
 479                 if (time_before(jiffies, dev_trans_start(dev) + 20 * HZ))  {
 480                         /* 20 sec timeout not reached */
 481                         goto out;
 482                 }
 483                 printk(KERN_WARNING "%s: transmit timed out, %s?\n",
 484                         dev->name,
 485                         (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
 486                                 "bad line quality" : "driver error");
 487                 sl->xleft = 0;
 488                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 489                 sl_unlock(sl);
 490 #endif
 491         }
 492 out:
 493         spin_unlock(&sl->lock);
 494 }
 495
 496
 497 /* Encapsulate an IP datagram and kick it into a TTY queue. */
 498 static netdev_tx_t
 499 sl_xmit(struct sk_buff *skb, struct net_device *dev)
 500 {
 501         struct slip *sl = netdev_priv(dev);
 502
 503         spin_lock(&sl->lock);
 504         if (!netif_running(dev)) {
 505                 spin_unlock(&sl->lock);
 506                 printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name);
 507                 dev_kfree_skb(skb);
 508                 return NETDEV_TX_OK;
 509         }
 510         if (sl->tty == NULL) {
 511                 spin_unlock(&sl->lock);
 512                 dev_kfree_skb(skb);
 513                 return NETDEV_TX_OK;
 514         }
 515
 516         sl_lock(sl);
 517         dev->stats.tx_bytes += skb->len;
 518         sl_encaps(sl, skb->data, skb->len);
 519         spin_unlock(&sl->lock);
 520
 521         dev_kfree_skb(skb);
 522         return NETDEV_TX_OK;
 523 }
 524
 525
 526 /******************************************
 527  *   Routines looking at netdevice side.
 528  ******************************************/
 529
 530 /* Netdevice UP -> DOWN routine */
 531
 532 static int
 533 sl_close(struct net_device *dev)
 534 {
 535         struct slip *sl = netdev_priv(dev);
 536
 537         spin_lock_bh(&sl->lock);
 538         if (sl->tty)
 539                 /* TTY discipline is running. */
 540                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 541         netif_stop_queue(dev);
 542         sl->rcount   = 0;
 543         sl->xleft    = 0;
 544         spin_unlock_bh(&sl->lock);
 545
 546         return 0;
 547 }
 548
 549 /* Netdevice DOWN -> UP routine */
 550
 551 static int sl_open(struct net_device *dev)
 552 {
 553         struct slip *sl = netdev_priv(dev);
 554
 555         if (sl->tty == NULL)
 556                 return -ENODEV;
 557
 558         sl->flags &= (1 << SLF_INUSE);
 559         netif_start_queue(dev);
 560         return 0;
 561 }
 562
 563 /* Netdevice change MTU request */
 564
 565 static int sl_change_mtu(struct net_device *dev, int new_mtu)
 566 {
 567         struct slip *sl = netdev_priv(dev);
 568
 569         return sl_realloc_bufs(sl, new_mtu);
 570 }
 571
 572 /* Netdevice get statistics request */
 573
 574 static void
 575 sl_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
 576 {
 577         struct net_device_stats *devstats = &dev->stats;
 578 #ifdef SL_INCLUDE_CSLIP
 579         struct slip *sl = netdev_priv(dev);
 580         struct slcompress *comp = sl->slcomp;
 581 #endif
 582         stats->rx_packets     = devstats->rx_packets;
 583         stats->tx_packets     = devstats->tx_packets;
 584         stats->rx_bytes       = devstats->rx_bytes;
 585         stats->tx_bytes       = devstats->tx_bytes;
 586         stats->rx_dropped     = devstats->rx_dropped;
 587         stats->tx_dropped     = devstats->tx_dropped;
 588         stats->tx_errors      = devstats->tx_errors;
 589         stats->rx_errors      = devstats->rx_errors;
 590         stats->rx_over_errors = devstats->rx_over_errors;
 591
 592 #ifdef SL_INCLUDE_CSLIP
 593         if (comp) {
 594                 /* Generic compressed statistics */
 595                 stats->rx_compressed   = comp->sls_i_compressed;
 596                 stats->tx_compressed   = comp->sls_o_compressed;
 597
 598                 /* Are we really still needs this? */
 599                 stats->rx_fifo_errors += comp->sls_i_compressed;
 600                 stats->rx_dropped     += comp->sls_i_tossed;
 601                 stats->tx_fifo_errors += comp->sls_o_compressed;
 602                 stats->collisions     += comp->sls_o_misses;
 603         }
 604 #endif
 605 }
 606
 607 /* Netdevice register callback */
 608
 609 static int sl_init(struct net_device *dev)
 610 {
 611         struct slip *sl = netdev_priv(dev);
 612
 613         /*
 614          *      Finish setting up the DEVICE info.
 615          */
 616
 617         dev->mtu                = sl->mtu;
 618         dev->type               = ARPHRD_SLIP + sl->mode;
 619 #ifdef SL_CHECK_TRANSMIT
 620         dev->watchdog_timeo     = 20*HZ;
 621 #endif
 622         return 0;
 623 }
 624
 625
 626 static void sl_uninit(struct net_device *dev)
 627 {
 628         struct slip *sl = netdev_priv(dev);
 629
 630         sl_free_bufs(sl);
 631 }
 632
 633 /* Hook the destructor so we can free slip devices at the right point in time */
 634 static void sl_free_netdev(struct net_device *dev)
 635 {
 636         int i = dev->base_addr;
 637
 638         slip_devs[i] = NULL;
 639 }
 640
 641 static const struct net_device_ops sl_netdev_ops = {
 642         .ndo_init               = sl_init,
 643         .ndo_uninit             = sl_uninit,
 644         .ndo_open               = sl_open,
 645         .ndo_stop               = sl_close,
 646         .ndo_start_xmit         = sl_xmit,
 647         .ndo_get_stats64        = sl_get_stats64,
 648         .ndo_change_mtu         = sl_change_mtu,
 649         .ndo_tx_timeout         = sl_tx_timeout,
 650 #ifdef CONFIG_SLIP_SMART
 651         .ndo_siocdevprivate     = sl_siocdevprivate,
 652 #endif
 653 };
 654
 655
 656 static void sl_setup(struct net_device *dev)
 657 {
 658         dev->netdev_ops         = &sl_netdev_ops;
 659         dev->needs_free_netdev  = true;
 660         dev->priv_destructor    = sl_free_netdev;
 661
 662         dev->hard_header_len    = 0;
 663         dev->addr_len           = 0;
 664         dev->tx_queue_len       = 10;
 665
 666         /* MTU range: 68 - 65534 */
 667         dev->min_mtu = 68;
 668         dev->max_mtu = 65534;
 669
 670         /* New-style flags. */
 671         dev->flags              = IFF_NOARP|IFF_POINTOPOINT|IFF_MULTICAST;
 672 }
 673
 674 /******************************************
 675   Routines looking at TTY side.
 676  ******************************************/
 677
 678
 679 /*
 680  * Handle the 'receiver data ready' interrupt.
 681  * This function is called by the 'tty_io' module in the kernel when
 682  * a block of SLIP data has been received, which can now be decapsulated
 683  * and sent on to some IP layer for further processing. This will not
 684  * be re-entered while running but other ldisc functions may be called
 685  * in parallel
 686  */
 687
 688 static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 689                 const char *fp, int count)
 690 {
 691         struct slip *sl = tty->disc_data;
 692
 693         if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
 694                 return;
 695
 696         /* Read the characters out of the buffer */
 697         while (count--) {
 698                 if (fp && *fp++) {
 699                         if (!test_and_set_bit(SLF_ERROR, &sl->flags))
 700                                 sl->dev->stats.rx_errors++;
 701                         cp++;
 702                         continue;
 703                 }
 704 #ifdef CONFIG_SLIP_MODE_SLIP6
 705                 if (sl->mode & SL_MODE_SLIP6)
 706                         slip_unesc6(sl, *cp++);
 707                 else
 708 #endif
 709                         slip_unesc(sl, *cp++);
 710         }
 711 }
 712
 713 /************************************
 714  *  slip_open helper routines.
 715  ************************************/
 716
 717 /* Collect hanged up channels */
 718 static void sl_sync(void)
 719 {
 720         int i;
 721         struct net_device *dev;
 722         struct slip       *sl;
 723
 724         for (i = 0; i < slip_maxdev; i++) {
 725                 dev = slip_devs[i];
 726                 if (dev == NULL)
 727                         break;
 728
 729                 sl = netdev_priv(dev);
 730                 if (sl->tty || sl->leased)
 731                         continue;
 732                 if (dev->flags & IFF_UP)
 733                         dev_close(dev);
 734         }
 735 }
 736
 737
 738 /* Find a free SLIP channel, and link in this `tty' line. */
 739 static struct slip *sl_alloc(void)
 740 {
 741         int i;
 742         char name[IFNAMSIZ];
 743         struct net_device *dev = NULL;
 744         struct slip       *sl;
 745
 746         for (i = 0; i < slip_maxdev; i++) {
 747                 dev = slip_devs[i];
 748                 if (dev == NULL)
 749                         break;
 750         }
 751         /* Sorry, too many, all slots in use */
 752         if (i >= slip_maxdev)
 753                 return NULL;
 754
 755         sprintf(name, "sl%d", i);
 756         dev = alloc_netdev(sizeof(*sl), name, NET_NAME_UNKNOWN, sl_setup);
 757         if (!dev)
 758                 return NULL;
 759
 760         dev->base_addr  = i;
 761         sl = netdev_priv(dev);
 762
 763         /* Initialize channel control data */
 764         sl->magic       = SLIP_MAGIC;
 765         sl->dev         = dev;
 766         spin_lock_init(&sl->lock);
 767         INIT_WORK(&sl->tx_work, slip_transmit);
 768         sl->mode        = SL_MODE_DEFAULT;
 769 #ifdef CONFIG_SLIP_SMART
 770         /* initialize timer_list struct */
 771         timer_setup(&sl->keepalive_timer, sl_keepalive, 0);
 772         timer_setup(&sl->outfill_timer, sl_outfill, 0);
 773 #endif
 774         slip_devs[i] = dev;
 775         return sl;
 776 }
 777
 778 /*
 779  * Open the high-level part of the SLIP channel.
 780  * This function is called by the TTY module when the
 781  * SLIP line discipline is called for.  Because we are
 782  * sure the tty line exists, we only have to link it to
 783  * a free SLIP channel...
 784  *
 785  * Called in process context serialized from other ldisc calls.
 786  */
 787
 788 static int slip_open(struct tty_struct *tty)
 789 {
 790         struct slip *sl;
 791         int err;
 792
 793         if (!capable(CAP_NET_ADMIN))
 794                 return -EPERM;
 795
 796         if (tty->ops->write == NULL)
 797                 return -EOPNOTSUPP;
 798
 799         /* RTnetlink lock is misused here to serialize concurrent
 800            opens of slip channels. There are better ways, but it is
 801            the simplest one.
 802          */
 803         rtnl_lock();
 804
 805         /* Collect hanged up channels. */
 806         sl_sync();
 807
 808         sl = tty->disc_data;
 809
 810         err = -EEXIST;
 811         /* First make sure we're not already connected. */
 812         if (sl && sl->magic == SLIP_MAGIC)
 813                 goto err_exit;
 814
 815         /* OK.  Find a free SLIP channel to use. */
 816         err = -ENFILE;
 817         sl = sl_alloc();
 818         if (sl == NULL)
 819                 goto err_exit;
 820
 821         sl->tty = tty;
 822         tty->disc_data = sl;
 823         sl->pid = current->pid;
 824
 825         if (!test_bit(SLF_INUSE, &sl->flags)) {
 826                 /* Perform the low-level SLIP initialization. */
 827                 err = sl_alloc_bufs(sl, SL_MTU);
 828                 if (err)
 829                         goto err_free_chan;
 830
 831                 set_bit(SLF_INUSE, &sl->flags);
 832
 833                 err = register_netdevice(sl->dev);
 834                 if (err)
 835                         goto err_free_bufs;
 836         }
 837
 838 #ifdef CONFIG_SLIP_SMART
 839         if (sl->keepalive) {
 840                 sl->keepalive_timer.expires = jiffies + sl->keepalive * HZ;
 841                 add_timer(&sl->keepalive_timer);
 842         }
 843         if (sl->outfill) {
 844                 sl->outfill_timer.expires = jiffies + sl->outfill * HZ;
 845                 add_timer(&sl->outfill_timer);
 846         }
 847 #endif
 848
 849         /* Done.  We have linked the TTY line to a channel. */
 850         rtnl_unlock();
 851         tty->receive_room = 65536;      /* We don't flow control */
 852
 853         /* TTY layer expects 0 on success */
 854         return 0;
 855
 856 err_free_bufs:
 857         sl_free_bufs(sl);
 858
 859 err_free_chan:
 860         sl->tty = NULL;
 861         tty->disc_data = NULL;
 862         clear_bit(SLF_INUSE, &sl->flags);
 863         sl_free_netdev(sl->dev);
 864         /* do not call free_netdev before rtnl_unlock */
 865         rtnl_unlock();
 866         free_netdev(sl->dev);
 867         return err;
 868
 869 err_exit:
 870         rtnl_unlock();
 871
 872         /* Count references from TTY module */
 873         return err;
 874 }
 875
 876 /*
 877  * Close down a SLIP channel.
 878  * This means flushing out any pending queues, and then returning. This
 879  * call is serialized against other ldisc functions.
 880  *
 881  * We also use this method fo a hangup event
 882  */
 883
 884 static void slip_close(struct tty_struct *tty)
 885 {
 886         struct slip *sl = tty->disc_data;
 887
 888         /* First make sure we're connected. */
 889         if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty)
 890                 return;
 891
 892         spin_lock_bh(&sl->lock);
 893         rcu_assign_pointer(tty->disc_data, NULL);
 894         sl->tty = NULL;
 895         spin_unlock_bh(&sl->lock);
 896
 897         synchronize_rcu();
 898         flush_work(&sl->tx_work);
 899
 900         /* VSV = very important to remove timers */
 901 #ifdef CONFIG_SLIP_SMART
 902         del_timer_sync(&sl->keepalive_timer);
 903         del_timer_sync(&sl->outfill_timer);
 904 #endif
 905         /* Flush network side */
 906         unregister_netdev(sl->dev);
 907         /* This will complete via sl_free_netdev */
 908 }
 909
 910 static void slip_hangup(struct tty_struct *tty)
 911 {
 912         slip_close(tty);
 913 }
 914  /************************************************************************
 915   *                     STANDARD SLIP ENCAPSULATION                      *
 916   ************************************************************************/
 917
 918 static int slip_esc(unsigned char *s, unsigned char *d, int len)
 919 {
 920         unsigned char *ptr = d;
 921         unsigned char c;
 922
 923         /*
 924          * Send an initial END character to flush out any
 925          * data that may have accumulated in the receiver
 926          * due to line noise.
 927          */
 928
 929         *ptr++ = END;
 930
 931         /*
 932          * For each byte in the packet, send the appropriate
 933          * character sequence, according to the SLIP protocol.
 934          */
 935
 936         while (len-- > 0) {
 937                 switch (c = *s++) {
 938                 case END:
 939                         *ptr++ = ESC;
 940                         *ptr++ = ESC_END;
 941                         break;
 942                 case ESC:
 943                         *ptr++ = ESC;
 944                         *ptr++ = ESC_ESC;
 945                         break;
 946                 default:
 947                         *ptr++ = c;
 948                         break;
 949                 }
 950         }
 951         *ptr++ = END;
 952         return ptr - d;
 953 }
 954
 955 static void slip_unesc(struct slip *sl, unsigned char s)
 956 {
 957
 958         switch (s) {
 959         case END:
 960 #ifdef CONFIG_SLIP_SMART
 961                 /* drop keeptest bit = VSV */
 962                 if (test_bit(SLF_KEEPTEST, &sl->flags))
 963                         clear_bit(SLF_KEEPTEST, &sl->flags);
 964 #endif
 965
 966                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
 967                     (sl->rcount > 2))
 968                         sl_bump(sl);
 969                 clear_bit(SLF_ESCAPE, &sl->flags);
 970                 sl->rcount = 0;
 971                 return;
 972
 973         case ESC:
 974                 set_bit(SLF_ESCAPE, &sl->flags);
 975                 return;
 976         case ESC_ESC:
 977                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 978                         s = ESC;
 979                 break;
 980         case ESC_END:
 981                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 982                         s = END;
 983                 break;
 984         }
 985         if (!test_bit(SLF_ERROR, &sl->flags))  {
 986                 if (sl->rcount < sl->buffsize)  {
 987                         sl->rbuff[sl->rcount++] = s;
 988                         return;
 989                 }
 990                 sl->dev->stats.rx_over_errors++;
 991                 set_bit(SLF_ERROR, &sl->flags);
 992         }
 993 }
 994
 995
 996 #ifdef CONFIG_SLIP_MODE_SLIP6
 997 /************************************************************************
 998  *                       6 BIT SLIP ENCAPSULATION                       *
 999  ************************************************************************/
1000
1001 static int slip_esc6(unsigned char *s, unsigned char *d, int len)
1002 {
1003         unsigned char *ptr = d;
1004         unsigned char c;
1005         int i;
1006         unsigned short v = 0;
1007         short bits = 0;
1008
1009         /*
1010          * Send an initial END character to flush out any
1011          * data that may have accumulated in the receiver
1012          * due to line noise.
1013          */
1014
1015         *ptr++ = 0x70;
1016
1017         /*
1018          * Encode the packet into printable ascii characters
1019          */
1020
1021         for (i = 0; i < len; ++i) {
1022                 v = (v << 8) | s[i];
1023                 bits += 8;
1024                 while (bits >= 6) {
1025                         bits -= 6;
1026                         c = 0x30 + ((v >> bits) & 0x3F);
1027                         *ptr++ = c;
1028                 }
1029         }
1030         if (bits) {
1031                 c = 0x30 + ((v << (6 - bits)) & 0x3F);
1032                 *ptr++ = c;
1033         }
1034         *ptr++ = 0x70;
1035         return ptr - d;
1036 }
1037
1038 static void slip_unesc6(struct slip *sl, unsigned char s)
1039 {
1040         unsigned char c;
1041
1042         if (s == 0x70) {
1043 #ifdef CONFIG_SLIP_SMART
1044                 /* drop keeptest bit = VSV */
1045                 if (test_bit(SLF_KEEPTEST, &sl->flags))
1046                         clear_bit(SLF_KEEPTEST, &sl->flags);
1047 #endif
1048
1049                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
1050                     (sl->rcount > 2))
1051                         sl_bump(sl);
1052                 sl->rcount = 0;
1053                 sl->xbits = 0;
1054                 sl->xdata = 0;
1055         } else if (s >= 0x30 && s < 0x70) {
1056                 sl->xdata = (sl->xdata << 6) | ((s - 0x30) & 0x3F);
1057                 sl->xbits += 6;
1058                 if (sl->xbits >= 8) {
1059                         sl->xbits -= 8;
1060                         c = (unsigned char)(sl->xdata >> sl->xbits);
1061                         if (!test_bit(SLF_ERROR, &sl->flags))  {
1062                                 if (sl->rcount < sl->buffsize)  {
1063                                         sl->rbuff[sl->rcount++] = c;
1064                                         return;
1065                                 }
1066                                 sl->dev->stats.rx_over_errors++;
1067                                 set_bit(SLF_ERROR, &sl->flags);
1068                         }
1069                 }
1070         }
1071 }
1072 #endif /* CONFIG_SLIP_MODE_SLIP6 */
1073
1074 /* Perform I/O control on an active SLIP channel. */
1075 static int slip_ioctl(struct tty_struct *tty, unsigned int cmd,
1076                 unsigned long arg)
1077 {
1078         struct slip *sl = tty->disc_data;
1079         unsigned int tmp;
1080         int __user *p = (int __user *)arg;
1081
1082         /* First make sure we're connected. */
1083         if (!sl || sl->magic != SLIP_MAGIC)
1084                 return -EINVAL;
1085
1086         switch (cmd) {
1087         case SIOCGIFNAME:
1088                 tmp = strlen(sl->dev->name) + 1;
1089                 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
1090                         return -EFAULT;
1091                 return 0;
1092
1093         case SIOCGIFENCAP:
1094                 if (put_user(sl->mode, p))
1095                         return -EFAULT;
1096                 return 0;
1097
1098         case SIOCSIFENCAP:
1099                 if (get_user(tmp, p))
1100                         return -EFAULT;
1101 #ifndef SL_INCLUDE_CSLIP
1102                 if (tmp & (SL_MODE_CSLIP|SL_MODE_ADAPTIVE))
1103                         return -EINVAL;
1104 #else
1105                 if ((tmp & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) ==
1106                     (SL_MODE_ADAPTIVE | SL_MODE_CSLIP))
1107                         /* return -EINVAL; */
1108                         tmp &= ~SL_MODE_ADAPTIVE;
1109 #endif
1110 #ifndef CONFIG_SLIP_MODE_SLIP6
1111                 if (tmp & SL_MODE_SLIP6)
1112                         return -EINVAL;
1113 #endif
1114                 sl->mode = tmp;
1115                 sl->dev->type = ARPHRD_SLIP + sl->mode;
1116                 return 0;
1117
1118         case SIOCSIFHWADDR:
1119                 return -EINVAL;
1120
1121 #ifdef CONFIG_SLIP_SMART
1122         /* VSV changes start here */
1123         case SIOCSKEEPALIVE:
1124                 if (get_user(tmp, p))
1125                         return -EFAULT;
1126                 if (tmp > 255) /* max for unchar */
1127                         return -EINVAL;
1128
1129                 spin_lock_bh(&sl->lock);
1130                 if (!sl->tty) {
1131                         spin_unlock_bh(&sl->lock);
1132                         return -ENODEV;
1133                 }
1134                 sl->keepalive = (u8)tmp;
1135                 if (sl->keepalive != 0) {
1136                         mod_timer(&sl->keepalive_timer,
1137                                         jiffies + sl->keepalive * HZ);
1138                         set_bit(SLF_KEEPTEST, &sl->flags);
1139                 } else
1140                         del_timer(&sl->keepalive_timer);
1141                 spin_unlock_bh(&sl->lock);
1142                 return 0;
1143
1144         case SIOCGKEEPALIVE:
1145                 if (put_user(sl->keepalive, p))
1146                         return -EFAULT;
1147                 return 0;
1148
1149         case SIOCSOUTFILL:
1150                 if (get_user(tmp, p))
1151                         return -EFAULT;
1152                 if (tmp > 255) /* max for unchar */
1153                         return -EINVAL;
1154                 spin_lock_bh(&sl->lock);
1155                 if (!sl->tty) {
1156                         spin_unlock_bh(&sl->lock);
1157                         return -ENODEV;
1158                 }
1159                 sl->outfill = (u8)tmp;
1160                 if (sl->outfill != 0) {
1161                         mod_timer(&sl->outfill_timer,
1162                                                 jiffies + sl->outfill * HZ);
1163                         set_bit(SLF_OUTWAIT, &sl->flags);
1164                 } else
1165                         del_timer(&sl->outfill_timer);
1166                 spin_unlock_bh(&sl->lock);
1167                 return 0;
1168
1169         case SIOCGOUTFILL:
1170                 if (put_user(sl->outfill, p))
1171                         return -EFAULT;
1172                 return 0;
1173         /* VSV changes end */
1174 #endif
1175         default:
1176                 return tty_mode_ioctl(tty, cmd, arg);
1177         }
1178 }
1179
1180 /* VSV changes start here */
1181 #ifdef CONFIG_SLIP_SMART
1182 /* function sl_siocdevprivate called from net/core/dev.c
1183    to allow get/set outfill/keepalive parameter
1184    by ifconfig                                 */
1185
1186 static int sl_siocdevprivate(struct net_device *dev, struct ifreq *rq,
1187                              void __user *data, int cmd)
1188 {
1189         struct slip *sl = netdev_priv(dev);
1190         unsigned long *p = (unsigned long *)&rq->ifr_ifru;
1191
1192         if (sl == NULL)         /* Allocation failed ?? */
1193                 return -ENODEV;
1194
1195         if (in_compat_syscall())
1196                 return -EOPNOTSUPP;
1197
1198         spin_lock_bh(&sl->lock);
1199
1200         if (!sl->tty) {
1201                 spin_unlock_bh(&sl->lock);
1202                 return -ENODEV;
1203         }
1204
1205         switch (cmd) {
1206         case SIOCSKEEPALIVE:
1207                 /* max for unchar */
1208                 if ((unsigned)*p > 255) {
1209                         spin_unlock_bh(&sl->lock);
1210                         return -EINVAL;
1211                 }
1212                 sl->keepalive = (u8)*p;
1213                 if (sl->keepalive != 0) {
1214                         sl->keepalive_timer.expires =
1215                                                 jiffies + sl->keepalive * HZ;
1216                         mod_timer(&sl->keepalive_timer,
1217                                                 jiffies + sl->keepalive * HZ);
1218                         set_bit(SLF_KEEPTEST, &sl->flags);
1219                 } else
1220                         del_timer(&sl->keepalive_timer);
1221                 break;
1222
1223         case SIOCGKEEPALIVE:
1224                 *p = sl->keepalive;
1225                 break;
1226
1227         case SIOCSOUTFILL:
1228                 if ((unsigned)*p > 255) { /* max for unchar */
1229                         spin_unlock_bh(&sl->lock);
1230                         return -EINVAL;
1231                 }
1232                 sl->outfill = (u8)*p;
1233                 if (sl->outfill != 0) {
1234                         mod_timer(&sl->outfill_timer,
1235                                                 jiffies + sl->outfill * HZ);
1236                         set_bit(SLF_OUTWAIT, &sl->flags);
1237                 } else
1238                         del_timer(&sl->outfill_timer);
1239                 break;
1240
1241         case SIOCGOUTFILL:
1242                 *p = sl->outfill;
1243                 break;
1244
1245         case SIOCSLEASE:
1246                 /* Resolve race condition, when ioctl'ing hanged up
1247                    and opened by another process device.
1248                  */
1249                 if (sl->tty != current->signal->tty &&
1250                                                 sl->pid != current->pid) {
1251                         spin_unlock_bh(&sl->lock);
1252                         return -EPERM;
1253                 }
1254                 sl->leased = 0;
1255                 if (*p)
1256                         sl->leased = 1;
1257                 break;
1258
1259         case SIOCGLEASE:
1260                 *p = sl->leased;
1261         }
1262         spin_unlock_bh(&sl->lock);
1263         return 0;
1264 }
1265 #endif
1266 /* VSV changes end */
1267
1268 static struct tty_ldisc_ops sl_ldisc = {
1269         .owner          = THIS_MODULE,
1270         .num            = N_SLIP,
1271         .name           = "slip",
1272         .open           = slip_open,
1273         .close          = slip_close,
1274         .hangup         = slip_hangup,
1275         .ioctl          = slip_ioctl,
1276         .receive_buf    = slip_receive_buf,
1277         .write_wakeup   = slip_write_wakeup,
1278 };
1279
1280 static int __init slip_init(void)
1281 {
1282         int status;
1283
1284         if (slip_maxdev < 4)
1285                 slip_maxdev = 4; /* Sanity */
1286
1287         printk(KERN_INFO "SLIP: version %s (dynamic channels, max=%d)"
1288 #ifdef CONFIG_SLIP_MODE_SLIP6
1289                " (6 bit encapsulation enabled)"
1290 #endif
1291                ".\n",
1292                SLIP_VERSION, slip_maxdev);
1293 #if defined(SL_INCLUDE_CSLIP)
1294         printk(KERN_INFO "CSLIP: code copyright 1989 Regents of the University of California.\n");
1295 #endif
1296 #ifdef CONFIG_SLIP_SMART
1297         printk(KERN_INFO "SLIP linefill/keepalive option.\n");
1298 #endif
1299
1300         slip_devs = kcalloc(slip_maxdev, sizeof(struct net_device *),
1301                                                                 GFP_KERNEL);
1302         if (!slip_devs)
1303                 return -ENOMEM;
1304
1305         /* Fill in our line protocol discipline, and register it */
1306         status = tty_register_ldisc(&sl_ldisc);
1307         if (status != 0) {
1308                 printk(KERN_ERR "SLIP: can't register line discipline (err = %d)\n", status);
1309                 kfree(slip_devs);
1310         }
1311         return status;
1312 }
1313
1314 static void __exit slip_exit(void)
1315 {
1316         int i;
1317         struct net_device *dev;
1318         struct slip *sl;
1319         unsigned long timeout = jiffies + HZ;
1320         int busy = 0;
1321
1322         if (slip_devs == NULL)
1323                 return;
1324
1325         /* First of all: check for active disciplines and hangup them.
1326          */
1327         do {
1328                 if (busy)
1329                         msleep_interruptible(100);
1330
1331                 busy = 0;
1332                 for (i = 0; i < slip_maxdev; i++) {
1333                         dev = slip_devs[i];
1334                         if (!dev)
1335                                 continue;
1336                         sl = netdev_priv(dev);
1337                         spin_lock_bh(&sl->lock);
1338                         if (sl->tty) {
1339                                 busy++;
1340                                 tty_hangup(sl->tty);
1341                         }
1342                         spin_unlock_bh(&sl->lock);
1343                 }
1344         } while (busy && time_before(jiffies, timeout));
1345
1346         /* FIXME: hangup is async so we should wait when doing this second
1347            phase */
1348
1349         for (i = 0; i < slip_maxdev; i++) {
1350                 dev = slip_devs[i];
1351                 if (!dev)
1352                         continue;
1353                 slip_devs[i] = NULL;
1354
1355                 sl = netdev_priv(dev);
1356                 if (sl->tty) {
1357                         printk(KERN_ERR "%s: tty discipline still running\n",
1358                                dev->name);
1359                 }
1360
1361                 unregister_netdev(dev);
1362         }
1363
1364         kfree(slip_devs);
1365         slip_devs = NULL;
1366
1367         tty_unregister_ldisc(&sl_ldisc);
1368 }
1369
1370 module_init(slip_init);
1371 module_exit(slip_exit);
1372
1373 #ifdef CONFIG_SLIP_SMART
1374 /*
1375  * This is start of the code for multislip style line checking
1376  * added by Stanislav Voronyi. All changes before marked VSV
1377  */
1378
1379 static void sl_outfill(struct timer_list *t)
1380 {
1381         struct slip *sl = from_timer(sl, t, outfill_timer);
1382
1383         spin_lock(&sl->lock);
1384
1385         if (sl->tty == NULL)
1386                 goto out;
1387
1388         if (sl->outfill) {
1389                 if (test_bit(SLF_OUTWAIT, &sl->flags)) {
1390                         /* no packets were transmitted, do outfill */
1391 #ifdef CONFIG_SLIP_MODE_SLIP6
1392                         unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END;
1393 #else
1394                         unsigned char s = END;
1395 #endif
1396                         /* put END into tty queue. Is it right ??? */
1397                         if (!netif_queue_stopped(sl->dev)) {
1398                                 /* if device busy no outfill */
1399                                 sl->tty->ops->write(sl->tty, &s, 1);
1400                         }
1401                 } else
1402                         set_bit(SLF_OUTWAIT, &sl->flags);
1403
1404                 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
1405         }
1406 out:
1407         spin_unlock(&sl->lock);
1408 }
1409
1410 static void sl_keepalive(struct timer_list *t)
1411 {
1412         struct slip *sl = from_timer(sl, t, keepalive_timer);
1413
1414         spin_lock(&sl->lock);
1415
1416         if (sl->tty == NULL)
1417                 goto out;
1418
1419         if (sl->keepalive) {
1420                 if (test_bit(SLF_KEEPTEST, &sl->flags)) {
1421                         /* keepalive still high :(, we must hangup */
1422                         if (sl->outfill)
1423                                 /* outfill timer must be deleted too */
1424                                 (void)del_timer(&sl->outfill_timer);
1425                         printk(KERN_DEBUG "%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name);
1426                         /* this must hangup tty & close slip */
1427                         tty_hangup(sl->tty);
1428                         /* I think we need not something else */
1429                         goto out;
1430                 } else
1431                         set_bit(SLF_KEEPTEST, &sl->flags);
1432
1433                 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
1434         }
1435 out:
1436         spin_unlock(&sl->lock);
1437 }
1438
1439 #endif
1440 MODULE_LICENSE("GPL");
1441 MODULE_ALIAS_LDISC(N_SLIP);