drivers/net/slip/slip.c

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

DEFINITIONS
