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, <[email protected]>
  10  *              Fred N. van Kempen, <[email protected]>
  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 <[email protected]>
  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/module.h>
  66 #include <linux/moduleparam.h>
  67
  68 #include <linux/uaccess.h>
  69 #include <linux/bitops.h>
  70 #include <linux/sched/signal.h>
  71 #include <linux/string.h>
  72 #include <linux/mm.h>
  73 #include <linux/interrupt.h>
  74 #include <linux/in.h>
  75 #include <linux/tty.h>
  76 #include <linux/errno.h>
  77 #include <linux/netdevice.h>
  78 #include <linux/etherdevice.h>
  79 #include <linux/skbuff.h>
  80 #include <linux/rtnetlink.h>
  81 #include <linux/if_arp.h>
  82 #include <linux/if_slip.h>
  83 #include <linux/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(struct timer_list *t);
 110 static void sl_outfill(struct timer_list *t);
 111 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
 112 #endif
 113
 114 /********************************
 115 *  Buffer administration routines:
 116 *       sl_alloc_bufs()
 117 *       sl_free_bufs()
 118 *       sl_realloc_bufs()
 119 *
 120 * NOTE: sl_realloc_bufs != sl_free_bufs + sl_alloc_bufs, because
 121 *       sl_realloc_bufs provides strong atomicity and reallocation
 122 *       on actively running device.
 123 *********************************/
 124
 125 /*
 126    Allocate channel buffers.
 127  */
 128
 129 static int sl_alloc_bufs(struct slip *sl, int mtu)
 130 {
 131         int err = -ENOBUFS;
 132         unsigned long len;
 133         char *rbuff = NULL;
 134         char *xbuff = NULL;
 135 #ifdef SL_INCLUDE_CSLIP
 136         char *cbuff = NULL;
 137         struct slcompress *slcomp = NULL;
 138 #endif
 139
 140         /*
 141          * Allocate the SLIP frame buffers:
 142          *
 143          * rbuff        Receive buffer.
 144          * xbuff        Transmit buffer.
 145          * cbuff        Temporary compression buffer.
 146          */
 147         len = mtu * 2;
 148
 149         /*
 150          * allow for arrival of larger UDP packets, even if we say not to
 151          * also fixes a bug in which SunOS sends 512-byte packets even with
 152          * an MSS of 128
 153          */
 154         if (len < 576 * 2)
 155                 len = 576 * 2;
 156         rbuff = kmalloc(len + 4, GFP_KERNEL);
 157         if (rbuff == NULL)
 158                 goto err_exit;
 159         xbuff = kmalloc(len + 4, GFP_KERNEL);
 160         if (xbuff == NULL)
 161                 goto err_exit;
 162 #ifdef SL_INCLUDE_CSLIP
 163         cbuff = kmalloc(len + 4, GFP_KERNEL);
 164         if (cbuff == NULL)
 165                 goto err_exit;
 166         slcomp = slhc_init(16, 16);
 167         if (IS_ERR(slcomp))
 168                 goto err_exit;
 169 #endif
 170         spin_lock_bh(&sl->lock);
 171         if (sl->tty == NULL) {
 172                 spin_unlock_bh(&sl->lock);
 173                 err = -ENODEV;
 174                 goto err_exit;
 175         }
 176         sl->mtu      = mtu;
 177         sl->buffsize = len;
 178         sl->rcount   = 0;
 179         sl->xleft    = 0;
 180         rbuff = xchg(&sl->rbuff, rbuff);
 181         xbuff = xchg(&sl->xbuff, xbuff);
 182 #ifdef SL_INCLUDE_CSLIP
 183         cbuff = xchg(&sl->cbuff, cbuff);
 184         slcomp = xchg(&sl->slcomp, slcomp);
 185 #endif
 186 #ifdef CONFIG_SLIP_MODE_SLIP6
 187         sl->xdata    = 0;
 188         sl->xbits    = 0;
 189 #endif
 190         spin_unlock_bh(&sl->lock);
 191         err = 0;
 192
 193         /* Cleanup */
 194 err_exit:
 195 #ifdef SL_INCLUDE_CSLIP
 196         kfree(cbuff);
 197         slhc_free(slcomp);
 198 #endif
 199         kfree(xbuff);
 200         kfree(rbuff);
 201         return err;
 202 }
 203
 204 /* Free a SLIP channel buffers. */
 205 static void sl_free_bufs(struct slip *sl)
 206 {
 207         /* Free all SLIP frame buffers. */
 208         kfree(xchg(&sl->rbuff, NULL));
 209         kfree(xchg(&sl->xbuff, NULL));
 210 #ifdef SL_INCLUDE_CSLIP
 211         kfree(xchg(&sl->cbuff, NULL));
 212         slhc_free(xchg(&sl->slcomp, NULL));
 213 #endif
 214 }
 215
 216 /*
 217    Reallocate slip channel buffers.
 218  */
 219
 220 static int sl_realloc_bufs(struct slip *sl, int mtu)
 221 {
 222         int err = 0;
 223         struct net_device *dev = sl->dev;
 224         unsigned char *xbuff, *rbuff;
 225 #ifdef SL_INCLUDE_CSLIP
 226         unsigned char *cbuff;
 227 #endif
 228         int len = mtu * 2;
 229
 230 /*
 231  * allow for arrival of larger UDP packets, even if we say not to
 232  * also fixes a bug in which SunOS sends 512-byte packets even with
 233  * an MSS of 128
 234  */
 235         if (len < 576 * 2)
 236                 len = 576 * 2;
 237
 238         xbuff = kmalloc(len + 4, GFP_ATOMIC);
 239         rbuff = kmalloc(len + 4, GFP_ATOMIC);
 240 #ifdef SL_INCLUDE_CSLIP
 241         cbuff = kmalloc(len + 4, GFP_ATOMIC);
 242 #endif
 243
 244
 245 #ifdef SL_INCLUDE_CSLIP
 246         if (xbuff == NULL || rbuff == NULL || cbuff == NULL)  {
 247 #else
 248         if (xbuff == NULL || rbuff == NULL)  {
 249 #endif
 250                 if (mtu > sl->mtu) {
 251                         printk(KERN_WARNING "%s: unable to grow slip buffers, MTU change cancelled.\n",
 252                                dev->name);
 253                         err = -ENOBUFS;
 254                 }
 255                 goto done;
 256         }
 257         spin_lock_bh(&sl->lock);
 258
 259         err = -ENODEV;
 260         if (sl->tty == NULL)
 261                 goto done_on_bh;
 262
 263         xbuff    = xchg(&sl->xbuff, xbuff);
 264         rbuff    = xchg(&sl->rbuff, rbuff);
 265 #ifdef SL_INCLUDE_CSLIP
 266         cbuff    = xchg(&sl->cbuff, cbuff);
 267 #endif
 268         if (sl->xleft)  {
 269                 if (sl->xleft <= len)  {
 270                         memcpy(sl->xbuff, sl->xhead, sl->xleft);
 271                 } else  {
 272                         sl->xleft = 0;
 273                         dev->stats.tx_dropped++;
 274                 }
 275         }
 276         sl->xhead = sl->xbuff;
 277
 278         if (sl->rcount)  {
 279                 if (sl->rcount <= len) {
 280                         memcpy(sl->rbuff, rbuff, sl->rcount);
 281                 } else  {
 282                         sl->rcount = 0;
 283                         dev->stats.rx_over_errors++;
 284                         set_bit(SLF_ERROR, &sl->flags);
 285                 }
 286         }
 287         sl->mtu      = mtu;
 288         dev->mtu      = mtu;
 289         sl->buffsize = len;
 290         err = 0;
 291
 292 done_on_bh:
 293         spin_unlock_bh(&sl->lock);
 294
 295 done:
 296         kfree(xbuff);
 297         kfree(rbuff);
 298 #ifdef SL_INCLUDE_CSLIP
 299         kfree(cbuff);
 300 #endif
 301         return err;
 302 }
 303
 304
 305 /* Set the "sending" flag.  This must be atomic hence the set_bit. */
 306 static inline void sl_lock(struct slip *sl)
 307 {
 308         netif_stop_queue(sl->dev);
 309 }
 310
 311
 312 /* Clear the "sending" flag.  This must be atomic, hence the ASM. */
 313 static inline void sl_unlock(struct slip *sl)
 314 {
 315         netif_wake_queue(sl->dev);
 316 }
 317
 318 /* Send one completely decapsulated IP datagram to the IP layer. */
 319 static void sl_bump(struct slip *sl)
 320 {
 321         struct net_device *dev = sl->dev;
 322         struct sk_buff *skb;
 323         int count;
 324
 325         count = sl->rcount;
 326 #ifdef SL_INCLUDE_CSLIP
 327         if (sl->mode & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) {
 328                 unsigned char c = sl->rbuff[0];
 329                 if (c & SL_TYPE_COMPRESSED_TCP) {
 330                         /* ignore compressed packets when CSLIP is off */
 331                         if (!(sl->mode & SL_MODE_CSLIP)) {
 332                                 printk(KERN_WARNING "%s: compressed packet ignored\n", dev->name);
 333                                 return;
 334                         }
 335                         /* make sure we've reserved enough space for uncompress
 336                            to use */
 337                         if (count + 80 > sl->buffsize) {
 338                                 dev->stats.rx_over_errors++;
 339                                 return;
 340                         }
 341                         count = slhc_uncompress(sl->slcomp, sl->rbuff, count);
 342                         if (count <= 0)
 343                                 return;
 344                 } else if (c >= SL_TYPE_UNCOMPRESSED_TCP) {
 345                         if (!(sl->mode & SL_MODE_CSLIP)) {
 346                                 /* turn on header compression */
 347                                 sl->mode |= SL_MODE_CSLIP;
 348                                 sl->mode &= ~SL_MODE_ADAPTIVE;
 349                                 printk(KERN_INFO "%s: header compression turned on\n", dev->name);
 350                         }
 351                         sl->rbuff[0] &= 0x4f;
 352                         if (slhc_remember(sl->slcomp, sl->rbuff, count) <= 0)
 353                                 return;
 354                 }
 355         }
 356 #endif  /* SL_INCLUDE_CSLIP */
 357
 358         dev->stats.rx_bytes += count;
 359
 360         skb = dev_alloc_skb(count);
 361         if (skb == NULL) {
 362                 printk(KERN_WARNING "%s: memory squeeze, dropping packet.\n", dev->name);
 363                 dev->stats.rx_dropped++;
 364                 return;
 365         }
 366         skb->dev = dev;
 367         skb_put_data(skb, sl->rbuff, count);
 368         skb_reset_mac_header(skb);
 369         skb->protocol = htons(ETH_P_IP);
 370         netif_rx_ni(skb);
 371         dev->stats.rx_packets++;
 372 }
 373
 374 /* Encapsulate one IP datagram and stuff into a TTY queue. */
 375 static void sl_encaps(struct slip *sl, unsigned char *icp, int len)
 376 {
 377         unsigned char *p;
 378         int actual, count;
 379
 380         if (len > sl->mtu) {            /* Sigh, shouldn't occur BUT ... */
 381                 printk(KERN_WARNING "%s: truncating oversized transmit packet!\n", sl->dev->name);
 382                 sl->dev->stats.tx_dropped++;
 383                 sl_unlock(sl);
 384                 return;
 385         }
 386
 387         p = icp;
 388 #ifdef SL_INCLUDE_CSLIP
 389         if (sl->mode & SL_MODE_CSLIP)
 390                 len = slhc_compress(sl->slcomp, p, len, sl->cbuff, &p, 1);
 391 #endif
 392 #ifdef CONFIG_SLIP_MODE_SLIP6
 393         if (sl->mode & SL_MODE_SLIP6)
 394                 count = slip_esc6(p, sl->xbuff, len);
 395         else
 396 #endif
 397                 count = slip_esc(p, sl->xbuff, len);
 398
 399         /* Order of next two lines is *very* important.
 400          * When we are sending a little amount of data,
 401          * the transfer may be completed inside the ops->write()
 402          * routine, because it's running with interrupts enabled.
 403          * In this case we *never* got WRITE_WAKEUP event,
 404          * if we did not request it before write operation.
 405          *       14 Oct 1994  Dmitry Gorodchanin.
 406          */
 407         set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 408         actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
 409 #ifdef SL_CHECK_TRANSMIT
 410         netif_trans_update(sl->dev);
 411 #endif
 412         sl->xleft = count - actual;
 413         sl->xhead = sl->xbuff + actual;
 414 #ifdef CONFIG_SLIP_SMART
 415         /* VSV */
 416         clear_bit(SLF_OUTWAIT, &sl->flags);     /* reset outfill flag */
 417 #endif
 418 }
 419
 420 /* Write out any remaining transmit buffer. Scheduled when tty is writable */
 421 static void slip_transmit(struct work_struct *work)
 422 {
 423         struct slip *sl = container_of(work, struct slip, tx_work);
 424         int actual;
 425
 426         spin_lock_bh(&sl->lock);
 427         /* First make sure we're connected. */
 428         if (!sl->tty || sl->magic != SLIP_MAGIC || !netif_running(sl->dev)) {
 429                 spin_unlock_bh(&sl->lock);
 430                 return;
 431         }
 432
 433         if (sl->xleft <= 0)  {
 434                 /* Now serial buffer is almost free & we can start
 435                  * transmission of another packet */
 436                 sl->dev->stats.tx_packets++;
 437                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 438                 spin_unlock_bh(&sl->lock);
 439                 sl_unlock(sl);
 440                 return;
 441         }
 442
 443         actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
 444         sl->xleft -= actual;
 445         sl->xhead += actual;
 446         spin_unlock_bh(&sl->lock);
 447 }
 448
 449 /*
 450  * Called by the driver when there's room for more data.
 451  * Schedule the transmit.
 452  */
 453 static void slip_write_wakeup(struct tty_struct *tty)
 454 {
 455         struct slip *sl;
 456
 457         rcu_read_lock();
 458         sl = rcu_dereference(tty->disc_data);
 459         if (sl)
 460                 schedule_work(&sl->tx_work);
 461         rcu_read_unlock();
 462 }
 463
 464 static void sl_tx_timeout(struct net_device *dev, unsigned int txqueue)
 465 {
 466         struct slip *sl = netdev_priv(dev);
 467
 468         spin_lock(&sl->lock);
 469
 470         if (netif_queue_stopped(dev)) {
 471                 if (!netif_running(dev))
 472                         goto out;
 473
 474                 /* May be we must check transmitter timeout here ?
 475                  *      14 Oct 1994 Dmitry Gorodchanin.
 476                  */
 477 #ifdef SL_CHECK_TRANSMIT
 478                 if (time_before(jiffies, dev_trans_start(dev) + 20 * HZ))  {
 479                         /* 20 sec timeout not reached */
 480                         goto out;
 481                 }
 482                 printk(KERN_WARNING "%s: transmit timed out, %s?\n",
 483                         dev->name,
 484                         (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
 485                                 "bad line quality" : "driver error");
 486                 sl->xleft = 0;
 487                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 488                 sl_unlock(sl);
 489 #endif
 490         }
 491 out:
 492         spin_unlock(&sl->lock);
 493 }
 494
 495
 496 /* Encapsulate an IP datagram and kick it into a TTY queue. */
 497 static netdev_tx_t
 498 sl_xmit(struct sk_buff *skb, struct net_device *dev)
 499 {
 500         struct slip *sl = netdev_priv(dev);
 501
 502         spin_lock(&sl->lock);
 503         if (!netif_running(dev)) {
 504                 spin_unlock(&sl->lock);
 505                 printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name);
 506                 dev_kfree_skb(skb);
 507                 return NETDEV_TX_OK;
 508         }
 509         if (sl->tty == NULL) {
 510                 spin_unlock(&sl->lock);
 511                 dev_kfree_skb(skb);
 512                 return NETDEV_TX_OK;
 513         }
 514
 515         sl_lock(sl);
 516         dev->stats.tx_bytes += skb->len;
 517         sl_encaps(sl, skb->data, skb->len);
 518         spin_unlock(&sl->lock);
 519
 520         dev_kfree_skb(skb);
 521         return NETDEV_TX_OK;
 522 }
 523
 524
 525 /******************************************
 526  *   Routines looking at netdevice side.
 527  ******************************************/
 528
 529 /* Netdevice UP -> DOWN routine */
 530
 531 static int
 532 sl_close(struct net_device *dev)
 533 {
 534         struct slip *sl = netdev_priv(dev);
 535
 536         spin_lock_bh(&sl->lock);
 537         if (sl->tty)
 538                 /* TTY discipline is running. */
 539                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 540         netif_stop_queue(dev);
 541         sl->rcount   = 0;
 542         sl->xleft    = 0;
 543         spin_unlock_bh(&sl->lock);
 544
 545         return 0;
 546 }
 547
 548 /* Netdevice DOWN -> UP routine */
 549
 550 static int sl_open(struct net_device *dev)
 551 {
 552         struct slip *sl = netdev_priv(dev);
 553
 554         if (sl->tty == NULL)
 555                 return -ENODEV;
 556
 557         sl->flags &= (1 << SLF_INUSE);
 558         netif_start_queue(dev);
 559         return 0;
 560 }
 561
 562 /* Netdevice change MTU request */
 563
 564 static int sl_change_mtu(struct net_device *dev, int new_mtu)
 565 {
 566         struct slip *sl = netdev_priv(dev);
 567
 568         return sl_realloc_bufs(sl, new_mtu);
 569 }
 570
 571 /* Netdevice get statistics request */
 572
 573 static void
 574 sl_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
 575 {
 576         struct net_device_stats *devstats = &dev->stats;
 577 #ifdef SL_INCLUDE_CSLIP
 578         struct slip *sl = netdev_priv(dev);
 579         struct slcompress *comp = sl->slcomp;
 580 #endif
 581         stats->rx_packets     = devstats->rx_packets;
 582         stats->tx_packets     = devstats->tx_packets;
 583         stats->rx_bytes       = devstats->rx_bytes;
 584         stats->tx_bytes       = devstats->tx_bytes;
 585         stats->rx_dropped     = devstats->rx_dropped;
 586         stats->tx_dropped     = devstats->tx_dropped;
 587         stats->tx_errors      = devstats->tx_errors;
 588         stats->rx_errors      = devstats->rx_errors;
 589         stats->rx_over_errors = devstats->rx_over_errors;
 590
 591 #ifdef SL_INCLUDE_CSLIP
 592         if (comp) {
 593                 /* Generic compressed statistics */
 594                 stats->rx_compressed   = comp->sls_i_compressed;
 595                 stats->tx_compressed   = comp->sls_o_compressed;
 596
 597                 /* Are we really still needs this? */
 598                 stats->rx_fifo_errors += comp->sls_i_compressed;
 599                 stats->rx_dropped     += comp->sls_i_tossed;
 600                 stats->tx_fifo_errors += comp->sls_o_compressed;
 601                 stats->collisions     += comp->sls_o_misses;
 602         }
 603 #endif
 604 }
 605
 606 /* Netdevice register callback */
 607
 608 static int sl_init(struct net_device *dev)
 609 {
 610         struct slip *sl = netdev_priv(dev);
 611
 612         /*
 613          *      Finish setting up the DEVICE info.
 614          */
 615
 616         dev->mtu                = sl->mtu;
 617         dev->type               = ARPHRD_SLIP + sl->mode;
 618 #ifdef SL_CHECK_TRANSMIT
 619         dev->watchdog_timeo     = 20*HZ;
 620 #endif
 621         return 0;
 622 }
 623
 624
 625 static void sl_uninit(struct net_device *dev)
 626 {
 627         struct slip *sl = netdev_priv(dev);
 628
 629         sl_free_bufs(sl);
 630 }
 631
 632 /* Hook the destructor so we can free slip devices at the right point in time */
 633 static void sl_free_netdev(struct net_device *dev)
 634 {
 635         int i = dev->base_addr;
 636
 637         slip_devs[i] = NULL;
 638 }
 639
 640 static const struct net_device_ops sl_netdev_ops = {
 641         .ndo_init               = sl_init,
 642         .ndo_uninit             = sl_uninit,
 643         .ndo_open               = sl_open,
 644         .ndo_stop               = sl_close,
 645         .ndo_start_xmit         = sl_xmit,
 646         .ndo_get_stats64        = sl_get_stats64,
 647         .ndo_change_mtu         = sl_change_mtu,
 648         .ndo_tx_timeout         = sl_tx_timeout,
 649 #ifdef CONFIG_SLIP_SMART
 650         .ndo_do_ioctl           = sl_ioctl,
 651 #endif
 652 };
 653
 654
 655 static void sl_setup(struct net_device *dev)
 656 {
 657         dev->netdev_ops         = &sl_netdev_ops;
 658         dev->needs_free_netdev  = true;
 659         dev->priv_destructor    = sl_free_netdev;
 660
 661         dev->hard_header_len    = 0;
 662         dev->addr_len           = 0;
 663         dev->tx_queue_len       = 10;
 664
 665         /* MTU range: 68 - 65534 */
 666         dev->min_mtu = 68;
 667         dev->max_mtu = 65534;
 668
 669         /* New-style flags. */
 670         dev->flags              = IFF_NOARP|IFF_POINTOPOINT|IFF_MULTICAST;
 671 }
 672
 673 /******************************************
 674   Routines looking at TTY side.
 675  ******************************************/
 676
 677
 678 /*
 679  * Handle the 'receiver data ready' interrupt.
 680  * This function is called by the 'tty_io' module in the kernel when
 681  * a block of SLIP data has been received, which can now be decapsulated
 682  * and sent on to some IP layer for further processing. This will not
 683  * be re-entered while running but other ldisc functions may be called
 684  * in parallel
 685  */
 686
 687 static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 688                                                         char *fp, int count)
 689 {
 690         struct slip *sl = tty->disc_data;
 691
 692         if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
 693                 return;
 694
 695         /* Read the characters out of the buffer */
 696         while (count--) {
 697                 if (fp && *fp++) {
 698                         if (!test_and_set_bit(SLF_ERROR, &sl->flags))
 699                                 sl->dev->stats.rx_errors++;
 700                         cp++;
 701                         continue;
 702                 }
 703 #ifdef CONFIG_SLIP_MODE_SLIP6
 704                 if (sl->mode & SL_MODE_SLIP6)
 705                         slip_unesc6(sl, *cp++);
 706                 else
 707 #endif
 708                         slip_unesc(sl, *cp++);
 709         }
 710 }
 711
 712 /************************************
 713  *  slip_open helper routines.
 714  ************************************/
 715
 716 /* Collect hanged up channels */
 717 static void sl_sync(void)
 718 {
 719         int i;
 720         struct net_device *dev;
 721         struct slip       *sl;
 722
 723         for (i = 0; i < slip_maxdev; i++) {
 724                 dev = slip_devs[i];
 725                 if (dev == NULL)
 726                         break;
 727
 728                 sl = netdev_priv(dev);
 729                 if (sl->tty || sl->leased)
 730                         continue;
 731                 if (dev->flags & IFF_UP)
 732                         dev_close(dev);
 733         }
 734 }
 735
 736
 737 /* Find a free SLIP channel, and link in this `tty' line. */
 738 static struct slip *sl_alloc(void)
 739 {
 740         int i;
 741         char name[IFNAMSIZ];
 742         struct net_device *dev = NULL;
 743         struct slip       *sl;
 744
 745         for (i = 0; i < slip_maxdev; i++) {
 746                 dev = slip_devs[i];
 747                 if (dev == NULL)
 748                         break;
 749         }
 750         /* Sorry, too many, all slots in use */
 751         if (i >= slip_maxdev)
 752                 return NULL;
 753
 754         sprintf(name, "sl%d", i);
 755         dev = alloc_netdev(sizeof(*sl), name, NET_NAME_UNKNOWN, sl_setup);
 756         if (!dev)
 757                 return NULL;
 758
 759         dev->base_addr  = i;
 760         sl = netdev_priv(dev);
 761
 762         /* Initialize channel control data */
 763         sl->magic       = SLIP_MAGIC;
 764         sl->dev         = dev;
 765         spin_lock_init(&sl->lock);
 766         INIT_WORK(&sl->tx_work, slip_transmit);
 767         sl->mode        = SL_MODE_DEFAULT;
 768 #ifdef CONFIG_SLIP_SMART
 769         /* initialize timer_list struct */
 770         timer_setup(&sl->keepalive_timer, sl_keepalive, 0);
 771         timer_setup(&sl->outfill_timer, sl_outfill, 0);
 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();
 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         sl_free_netdev(sl->dev);
 863         /* do not call free_netdev before rtnl_unlock */
 864         rtnl_unlock();
 865         free_netdev(sl->dev);
 866         return err;
 867
 868 err_exit:
 869         rtnl_unlock();
 870
 871         /* Count references from TTY module */
 872         return err;
 873 }
 874
 875 /*
 876  * Close down a SLIP channel.
 877  * This means flushing out any pending queues, and then returning. This
 878  * call is serialized against other ldisc functions.
 879  *
 880  * We also use this method fo a hangup event
 881  */
 882
 883 static void slip_close(struct tty_struct *tty)
 884 {
 885         struct slip *sl = tty->disc_data;
 886
 887         /* First make sure we're connected. */
 888         if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty)
 889                 return;
 890
 891         spin_lock_bh(&sl->lock);
 892         rcu_assign_pointer(tty->disc_data, NULL);
 893         sl->tty = NULL;
 894         spin_unlock_bh(&sl->lock);
 895
 896         synchronize_rcu();
 897         flush_work(&sl->tx_work);
 898
 899         /* VSV = very important to remove timers */
 900 #ifdef CONFIG_SLIP_SMART
 901         del_timer_sync(&sl->keepalive_timer);
 902         del_timer_sync(&sl->outfill_timer);
 903 #endif
 904         /* Flush network side */
 905         unregister_netdev(sl->dev);
 906         /* This will complete via sl_free_netdev */
 907 }
 908
 909 static int slip_hangup(struct tty_struct *tty)
 910 {
 911         slip_close(tty);
 912         return 0;
 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, struct file *file,
1076                                         unsigned int cmd, 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, file, cmd, arg);
1177         }
1178 }
1179
1180 /* VSV changes start here */
1181 #ifdef CONFIG_SLIP_SMART
1182 /* function do_ioctl called from net/core/dev.c
1183    to allow get/set outfill/keepalive parameter
1184    by ifconfig                                 */
1185
1186 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
1187 {
1188         struct slip *sl = netdev_priv(dev);
1189         unsigned long *p = (unsigned long *)&rq->ifr_ifru;
1190
1191         if (sl == NULL)         /* Allocation failed ?? */
1192                 return -ENODEV;
1193
1194         spin_lock_bh(&sl->lock);
1195
1196         if (!sl->tty) {
1197                 spin_unlock_bh(&sl->lock);
1198                 return -ENODEV;
1199         }
1200
1201         switch (cmd) {
1202         case SIOCSKEEPALIVE:
1203                 /* max for unchar */
1204                 if ((unsigned)*p > 255) {
1205                         spin_unlock_bh(&sl->lock);
1206                         return -EINVAL;
1207                 }
1208                 sl->keepalive = (u8)*p;
1209                 if (sl->keepalive != 0) {
1210                         sl->keepalive_timer.expires =
1211                                                 jiffies + sl->keepalive * HZ;
1212                         mod_timer(&sl->keepalive_timer,
1213                                                 jiffies + sl->keepalive * HZ);
1214                         set_bit(SLF_KEEPTEST, &sl->flags);
1215                 } else
1216                         del_timer(&sl->keepalive_timer);
1217                 break;
1218
1219         case SIOCGKEEPALIVE:
1220                 *p = sl->keepalive;
1221                 break;
1222
1223         case SIOCSOUTFILL:
1224                 if ((unsigned)*p > 255) { /* max for unchar */
1225                         spin_unlock_bh(&sl->lock);
1226                         return -EINVAL;
1227                 }
1228                 sl->outfill = (u8)*p;
1229                 if (sl->outfill != 0) {
1230                         mod_timer(&sl->outfill_timer,
1231                                                 jiffies + sl->outfill * HZ);
1232                         set_bit(SLF_OUTWAIT, &sl->flags);
1233                 } else
1234                         del_timer(&sl->outfill_timer);
1235                 break;
1236
1237         case SIOCGOUTFILL:
1238                 *p = sl->outfill;
1239                 break;
1240
1241         case SIOCSLEASE:
1242                 /* Resolve race condition, when ioctl'ing hanged up
1243                    and opened by another process device.
1244                  */
1245                 if (sl->tty != current->signal->tty &&
1246                                                 sl->pid != current->pid) {
1247                         spin_unlock_bh(&sl->lock);
1248                         return -EPERM;
1249                 }
1250                 sl->leased = 0;
1251                 if (*p)
1252                         sl->leased = 1;
1253                 break;
1254
1255         case SIOCGLEASE:
1256                 *p = sl->leased;
1257         }
1258         spin_unlock_bh(&sl->lock);
1259         return 0;
1260 }
1261 #endif
1262 /* VSV changes end */
1263
1264 static struct tty_ldisc_ops sl_ldisc = {
1265         .owner          = THIS_MODULE,
1266         .magic          = TTY_LDISC_MAGIC,
1267         .name           = "slip",
1268         .open           = slip_open,
1269         .close          = slip_close,
1270         .hangup         = slip_hangup,
1271         .ioctl          = slip_ioctl,
1272         .receive_buf    = slip_receive_buf,
1273         .write_wakeup   = slip_write_wakeup,
1274 };
1275
1276 static int __init slip_init(void)
1277 {
1278         int status;
1279
1280         if (slip_maxdev < 4)
1281                 slip_maxdev = 4; /* Sanity */
1282
1283         printk(KERN_INFO "SLIP: version %s (dynamic channels, max=%d)"
1284 #ifdef CONFIG_SLIP_MODE_SLIP6
1285                " (6 bit encapsulation enabled)"
1286 #endif
1287                ".\n",
1288                SLIP_VERSION, slip_maxdev);
1289 #if defined(SL_INCLUDE_CSLIP)
1290         printk(KERN_INFO "CSLIP: code copyright 1989 Regents of the University of California.\n");
1291 #endif
1292 #ifdef CONFIG_SLIP_SMART
1293         printk(KERN_INFO "SLIP linefill/keepalive option.\n");
1294 #endif
1295
1296         slip_devs = kcalloc(slip_maxdev, sizeof(struct net_device *),
1297                                                                 GFP_KERNEL);
1298         if (!slip_devs)
1299                 return -ENOMEM;
1300
1301         /* Fill in our line protocol discipline, and register it */
1302         status = tty_register_ldisc(N_SLIP, &sl_ldisc);
1303         if (status != 0) {
1304                 printk(KERN_ERR "SLIP: can't register line discipline (err = %d)\n", status);
1305                 kfree(slip_devs);
1306         }
1307         return status;
1308 }
1309
1310 static void __exit slip_exit(void)
1311 {
1312         int i;
1313         struct net_device *dev;
1314         struct slip *sl;
1315         unsigned long timeout = jiffies + HZ;
1316         int busy = 0;
1317
1318         if (slip_devs == NULL)
1319                 return;
1320
1321         /* First of all: check for active disciplines and hangup them.
1322          */
1323         do {
1324                 if (busy)
1325                         msleep_interruptible(100);
1326
1327                 busy = 0;
1328                 for (i = 0; i < slip_maxdev; i++) {
1329                         dev = slip_devs[i];
1330                         if (!dev)
1331                                 continue;
1332                         sl = netdev_priv(dev);
1333                         spin_lock_bh(&sl->lock);
1334                         if (sl->tty) {
1335                                 busy++;
1336                                 tty_hangup(sl->tty);
1337                         }
1338                         spin_unlock_bh(&sl->lock);
1339                 }
1340         } while (busy && time_before(jiffies, timeout));
1341
1342         /* FIXME: hangup is async so we should wait when doing this second
1343            phase */
1344
1345         for (i = 0; i < slip_maxdev; i++) {
1346                 dev = slip_devs[i];
1347                 if (!dev)
1348                         continue;
1349                 slip_devs[i] = NULL;
1350
1351                 sl = netdev_priv(dev);
1352                 if (sl->tty) {
1353                         printk(KERN_ERR "%s: tty discipline still running\n",
1354                                dev->name);
1355                 }
1356
1357                 unregister_netdev(dev);
1358         }
1359
1360         kfree(slip_devs);
1361         slip_devs = NULL;
1362
1363         i = tty_unregister_ldisc(N_SLIP);
1364         if (i != 0)
1365                 printk(KERN_ERR "SLIP: can't unregister line discipline (err = %d)\n", i);
1366 }
1367
1368 module_init(slip_init);
1369 module_exit(slip_exit);
1370
1371 #ifdef CONFIG_SLIP_SMART
1372 /*
1373  * This is start of the code for multislip style line checking
1374  * added by Stanislav Voronyi. All changes before marked VSV
1375  */
1376
1377 static void sl_outfill(struct timer_list *t)
1378 {
1379         struct slip *sl = from_timer(sl, t, outfill_timer);
1380
1381         spin_lock(&sl->lock);
1382
1383         if (sl->tty == NULL)
1384                 goto out;
1385
1386         if (sl->outfill) {
1387                 if (test_bit(SLF_OUTWAIT, &sl->flags)) {
1388                         /* no packets were transmitted, do outfill */
1389 #ifdef CONFIG_SLIP_MODE_SLIP6
1390                         unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END;
1391 #else
1392                         unsigned char s = END;
1393 #endif
1394                         /* put END into tty queue. Is it right ??? */
1395                         if (!netif_queue_stopped(sl->dev)) {
1396                                 /* if device busy no outfill */
1397                                 sl->tty->ops->write(sl->tty, &s, 1);
1398                         }
1399                 } else
1400                         set_bit(SLF_OUTWAIT, &sl->flags);
1401
1402                 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
1403         }
1404 out:
1405         spin_unlock(&sl->lock);
1406 }
1407
1408 static void sl_keepalive(struct timer_list *t)
1409 {
1410         struct slip *sl = from_timer(sl, t, keepalive_timer);
1411
1412         spin_lock(&sl->lock);
1413
1414         if (sl->tty == NULL)
1415                 goto out;
1416
1417         if (sl->keepalive) {
1418                 if (test_bit(SLF_KEEPTEST, &sl->flags)) {
1419                         /* keepalive still high :(, we must hangup */
1420                         if (sl->outfill)
1421                                 /* outfill timer must be deleted too */
1422                                 (void)del_timer(&sl->outfill_timer);
1423                         printk(KERN_DEBUG "%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name);
1424                         /* this must hangup tty & close slip */
1425                         tty_hangup(sl->tty);
1426                         /* I think we need not something else */
1427                         goto out;
1428                 } else
1429                         set_bit(SLF_KEEPTEST, &sl->flags);
1430
1431                 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
1432         }
1433 out:
1434         spin_unlock(&sl->lock);
1435 }
1436
1437 #endif
1438 MODULE_LICENSE("GPL");
1439 MODULE_ALIAS_LDISC(N_SLIP);