net, compat_ioctl: handle socket ioctl abuses in tty drivers
[linux-2.6.git] / drivers / net / slip.c
1 /*
2  * slip.c       This module implements the SLIP protocol for kernel-based
3  *              devices like TTY.  It interfaces between a raw TTY, and the
4  *              kernel's INET protocol layers.
5  *
6  * Version:     @(#)slip.c      0.8.3   12/24/94
7  *
8  * Authors:     Laurence Culhane, <loz@holmes.demon.co.uk>
9  *              Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
10  *
11  * Fixes:
12  *              Alan Cox        :       Sanity checks and avoid tx overruns.
13  *                                      Has a new sl->mtu field.
14  *              Alan Cox        :       Found cause of overrun. ifconfig sl0
15  *                                      mtu upwards. Driver now spots this
16  *                                      and grows/shrinks its buffers(hack!).
17  *                                      Memory leak if you run out of memory
18  *                                      setting up a slip driver fixed.
19  *              Matt Dillon     :       Printable slip (borrowed from NET2E)
20  *      Pauline Middelink       :       Slip driver fixes.
21  *              Alan Cox        :       Honours the old SL_COMPRESSED flag
22  *              Alan Cox        :       KISS AX.25 and AXUI IP support
23  *              Michael Riepe   :       Automatic CSLIP recognition added
24  *              Charles Hedrick :       CSLIP header length problem fix.
25  *              Alan Cox        :       Corrected non-IP cases of the above.
26  *              Alan Cox        :       Now uses hardware type as per FvK.
27  *              Alan Cox        :       Default to 192.168.0.0 (RFC 1597)
28  *              A.N.Kuznetsov   :       dev_tint() recursion fix.
29  *      Dmitry Gorodchanin      :       SLIP memory leaks
30  *      Dmitry Gorodchanin      :       Code cleanup. Reduce tty driver
31  *                                      buffering from 4096 to 256 bytes.
32  *                                      Improving SLIP response time.
33  *                                      CONFIG_SLIP_MODE_SLIP6.
34  *                                      ifconfig sl? up & down now works
35  *                                      correctly.
36  *                                      Modularization.
37  *              Alan Cox        :       Oops - fix AX.25 buffer lengths
38  *      Dmitry Gorodchanin      :       Even more cleanups. Preserve CSLIP
39  *                                      statistics. Include CSLIP code only
40  *                                      if it really needed.
41  *              Alan Cox        :       Free slhc buffers in the right place.
42  *              Alan Cox        :       Allow for digipeated IP over AX.25
43  *              Matti Aarnio    :       Dynamic SLIP devices, with ideas taken
44  *                                      from Jim Freeman's <jfree@caldera.com>
45  *                                      dynamic PPP devices.  We do NOT kfree()
46  *                                      device entries, just reg./unreg. them
47  *                                      as they are needed.  We kfree() them
48  *                                      at module cleanup.
49  *                                      With MODULE-loading ``insmod'', user
50  *                                      can issue parameter:  slip_maxdev=1024
51  *                                      (Or how much he/she wants.. Default
52  *                                      is 256)
53  *      Stanislav Voronyi       :       Slip line checking, with ideas taken
54  *                                      from multislip BSDI driver which was
55  *                                      written by Igor Chechik, RELCOM Corp.
56  *                                      Only algorithms have been ported to
57  *                                      Linux SLIP driver.
58  *      Vitaly E. Lavrov        :       Sane behaviour on tty hangup.
59  *      Alexey Kuznetsov        :       Cleanup interfaces to tty & netdevice
60  *                                      modules.
61  */
62
63 #define SL_CHECK_TRANSMIT
64 #include <linux/module.h>
65 #include <linux/moduleparam.h>
66
67 #include <asm/system.h>
68 #include <asm/uaccess.h>
69 #include <linux/bitops.h>
70 #include <linux/string.h>
71 #include <linux/mm.h>
72 #include <linux/interrupt.h>
73 #include <linux/in.h>
74 #include <linux/tty.h>
75 #include <linux/errno.h>
76 #include <linux/netdevice.h>
77 #include <linux/etherdevice.h>
78 #include <linux/skbuff.h>
79 #include <linux/rtnetlink.h>
80 #include <linux/if_arp.h>
81 #include <linux/if_slip.h>
82 #include <linux/compat.h>
83 #include <linux/delay.h>
84 #include <linux/init.h>
85 #include "slip.h"
86 #ifdef CONFIG_INET
87 #include <linux/ip.h>
88 #include <linux/tcp.h>
89 #include <net/slhc_vj.h>
90 #endif
91
92 #define SLIP_VERSION    "0.8.4-NET3.019-NEWTTY"
93
94 static struct net_device **slip_devs;
95
96 static int slip_maxdev = SL_NRUNIT;
97 module_param(slip_maxdev, int, 0);
98 MODULE_PARM_DESC(slip_maxdev, "Maximum number of slip devices");
99
100 static int slip_esc(unsigned char *p, unsigned char *d, int len);
101 static void slip_unesc(struct slip *sl, unsigned char c);
102 #ifdef CONFIG_SLIP_MODE_SLIP6
103 static int slip_esc6(unsigned char *p, unsigned char *d, int len);
104 static void slip_unesc6(struct slip *sl, unsigned char c);
105 #endif
106 #ifdef CONFIG_SLIP_SMART
107 static void sl_keepalive(unsigned long sls);
108 static void sl_outfill(unsigned long sls);
109 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
110 #endif
111
112 /********************************
113 *  Buffer administration routines:
114 *       sl_alloc_bufs()
115 *       sl_free_bufs()
116 *       sl_realloc_bufs()
117 *
118 * NOTE: sl_realloc_bufs != sl_free_bufs + sl_alloc_bufs, because
119 *       sl_realloc_bufs provides strong atomicity and reallocation
120 *       on actively running device.
121 *********************************/
122
123 /*
124    Allocate channel buffers.
125  */
126
127 static int sl_alloc_bufs(struct slip *sl, int mtu)
128 {
129         int err = -ENOBUFS;
130         unsigned long len;
131         char *rbuff = NULL;
132         char *xbuff = NULL;
133 #ifdef SL_INCLUDE_CSLIP
134         char *cbuff = NULL;
135         struct slcompress *slcomp = NULL;
136 #endif
137
138         /*
139          * Allocate the SLIP frame buffers:
140          *
141          * rbuff        Receive buffer.
142          * xbuff        Transmit buffer.
143          * cbuff        Temporary compression buffer.
144          */
145         len = mtu * 2;
146
147         /*
148          * allow for arrival of larger UDP packets, even if we say not to
149          * also fixes a bug in which SunOS sends 512-byte packets even with
150          * an MSS of 128
151          */
152         if (len < 576 * 2)
153                 len = 576 * 2;
154         rbuff = kmalloc(len + 4, GFP_KERNEL);
155         if (rbuff == NULL)
156                 goto err_exit;
157         xbuff = kmalloc(len + 4, GFP_KERNEL);
158         if (xbuff == NULL)
159                 goto err_exit;
160 #ifdef SL_INCLUDE_CSLIP
161         cbuff = kmalloc(len + 4, GFP_KERNEL);
162         if (cbuff == NULL)
163                 goto err_exit;
164         slcomp = slhc_init(16, 16);
165         if (slcomp == NULL)
166                 goto err_exit;
167 #endif
168         spin_lock_bh(&sl->lock);
169         if (sl->tty == NULL) {
170                 spin_unlock_bh(&sl->lock);
171                 err = -ENODEV;
172                 goto err_exit;
173         }
174         sl->mtu      = mtu;
175         sl->buffsize = len;
176         sl->rcount   = 0;
177         sl->xleft    = 0;
178         rbuff = xchg(&sl->rbuff, rbuff);
179         xbuff = xchg(&sl->xbuff, xbuff);
180 #ifdef SL_INCLUDE_CSLIP
181         cbuff = xchg(&sl->cbuff, cbuff);
182         slcomp = xchg(&sl->slcomp, slcomp);
183 #ifdef CONFIG_SLIP_MODE_SLIP6
184         sl->xdata    = 0;
185         sl->xbits    = 0;
186 #endif
187 #endif
188         spin_unlock_bh(&sl->lock);
189         err = 0;
190
191         /* Cleanup */
192 err_exit:
193 #ifdef SL_INCLUDE_CSLIP
194         kfree(cbuff);
195         if (slcomp)
196                 slhc_free(slcomp);
197 #endif
198         kfree(xbuff);
199         kfree(rbuff);
200         return err;
201 }
202
203 /* Free a SLIP channel buffers. */
204 static void sl_free_bufs(struct slip *sl)
205 {
206         /* Free all SLIP frame buffers. */
207         kfree(xchg(&sl->rbuff, NULL));
208         kfree(xchg(&sl->xbuff, NULL));
209 #ifdef SL_INCLUDE_CSLIP
210         kfree(xchg(&sl->cbuff, NULL));
211         slhc_free(xchg(&sl->slcomp, NULL));
212 #endif
213 }
214
215 /*
216    Reallocate slip channel buffers.
217  */
218
219 static int sl_realloc_bufs(struct slip *sl, int mtu)
220 {
221         int err = 0;
222         struct net_device *dev = sl->dev;
223         unsigned char *xbuff, *rbuff;
224 #ifdef SL_INCLUDE_CSLIP
225         unsigned char *cbuff;
226 #endif
227         int len = mtu * 2;
228
229 /*
230  * allow for arrival of larger UDP packets, even if we say not to
231  * also fixes a bug in which SunOS sends 512-byte packets even with
232  * an MSS of 128
233  */
234         if (len < 576 * 2)
235                 len = 576 * 2;
236
237         xbuff = kmalloc(len + 4, GFP_ATOMIC);
238         rbuff = kmalloc(len + 4, GFP_ATOMIC);
239 #ifdef SL_INCLUDE_CSLIP
240         cbuff = kmalloc(len + 4, GFP_ATOMIC);
241 #endif
242
243
244 #ifdef SL_INCLUDE_CSLIP
245         if (xbuff == NULL || rbuff == NULL || cbuff == NULL)  {
246 #else
247         if (xbuff == NULL || rbuff == NULL)  {
248 #endif
249                 if (mtu >= sl->mtu) {
250                         printk(KERN_WARNING "%s: unable to grow slip buffers, MTU change cancelled.\n",
251                                dev->name);
252                         err = -ENOBUFS;
253                 }
254                 goto done;
255         }
256         spin_lock_bh(&sl->lock);
257
258         err = -ENODEV;
259         if (sl->tty == NULL)
260                 goto done_on_bh;
261
262         xbuff    = xchg(&sl->xbuff, xbuff);
263         rbuff    = xchg(&sl->rbuff, rbuff);
264 #ifdef SL_INCLUDE_CSLIP
265         cbuff    = xchg(&sl->cbuff, cbuff);
266 #endif
267         if (sl->xleft)  {
268                 if (sl->xleft <= len)  {
269                         memcpy(sl->xbuff, sl->xhead, sl->xleft);
270                 } else  {
271                         sl->xleft = 0;
272                         sl->tx_dropped++;
273                 }
274         }
275         sl->xhead = sl->xbuff;
276
277         if (sl->rcount)  {
278                 if (sl->rcount <= len) {
279                         memcpy(sl->rbuff, rbuff, sl->rcount);
280                 } else  {
281                         sl->rcount = 0;
282                         sl->rx_over_errors++;
283                         set_bit(SLF_ERROR, &sl->flags);
284                 }
285         }
286         sl->mtu      = mtu;
287         dev->mtu      = mtu;
288         sl->buffsize = len;
289         err = 0;
290
291 done_on_bh:
292         spin_unlock_bh(&sl->lock);
293
294 done:
295         kfree(xbuff);
296         kfree(rbuff);
297 #ifdef SL_INCLUDE_CSLIP
298         kfree(cbuff);
299 #endif
300         return err;
301 }
302
303
304 /* Set the "sending" flag.  This must be atomic hence the set_bit. */
305 static inline void sl_lock(struct slip *sl)
306 {
307         netif_stop_queue(sl->dev);
308 }
309
310
311 /* Clear the "sending" flag.  This must be atomic, hence the ASM. */
312 static inline void sl_unlock(struct slip *sl)
313 {
314         netif_wake_queue(sl->dev);
315 }
316
317 /* Send one completely decapsulated IP datagram to the IP layer. */
318 static void sl_bump(struct slip *sl)
319 {
320         struct sk_buff *skb;
321         int count;
322
323         count = sl->rcount;
324 #ifdef SL_INCLUDE_CSLIP
325         if (sl->mode & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) {
326                 unsigned char c = sl->rbuff[0];
327                 if (c & SL_TYPE_COMPRESSED_TCP) {
328                         /* ignore compressed packets when CSLIP is off */
329                         if (!(sl->mode & SL_MODE_CSLIP)) {
330                                 printk(KERN_WARNING "%s: compressed packet ignored\n", sl->dev->name);
331                                 return;
332                         }
333                         /* make sure we've reserved enough space for uncompress
334                            to use */
335                         if (count + 80 > sl->buffsize) {
336                                 sl->rx_over_errors++;
337                                 return;
338                         }
339                         count = slhc_uncompress(sl->slcomp, sl->rbuff, count);
340                         if (count <= 0)
341                                 return;
342                 } else if (c >= SL_TYPE_UNCOMPRESSED_TCP) {
343                         if (!(sl->mode & SL_MODE_CSLIP)) {
344                                 /* turn on header compression */
345                                 sl->mode |= SL_MODE_CSLIP;
346                                 sl->mode &= ~SL_MODE_ADAPTIVE;
347                                 printk(KERN_INFO "%s: header compression turned on\n", sl->dev->name);
348                         }
349                         sl->rbuff[0] &= 0x4f;
350                         if (slhc_remember(sl->slcomp, sl->rbuff, count) <= 0)
351                                 return;
352                 }
353         }
354 #endif  /* SL_INCLUDE_CSLIP */
355
356         sl->rx_bytes += count;
357
358         skb = dev_alloc_skb(count);
359         if (skb == NULL) {
360                 printk(KERN_WARNING "%s: memory squeeze, dropping packet.\n", sl->dev->name);
361                 sl->rx_dropped++;
362                 return;
363         }
364         skb->dev = sl->dev;
365         memcpy(skb_put(skb, count), sl->rbuff, count);
366         skb_reset_mac_header(skb);
367         skb->protocol = htons(ETH_P_IP);
368         netif_rx(skb);
369         sl->rx_packets++;
370 }
371
372 /* Encapsulate one IP datagram and stuff into a TTY queue. */
373 static void sl_encaps(struct slip *sl, unsigned char *icp, int len)
374 {
375         unsigned char *p;
376         int actual, count;
377
378         if (len > sl->mtu) {            /* Sigh, shouldn't occur BUT ... */
379                 printk(KERN_WARNING "%s: truncating oversized transmit packet!\n", sl->dev->name);
380                 sl->tx_dropped++;
381                 sl_unlock(sl);
382                 return;
383         }
384
385         p = icp;
386 #ifdef SL_INCLUDE_CSLIP
387         if (sl->mode & SL_MODE_CSLIP)
388                 len = slhc_compress(sl->slcomp, p, len, sl->cbuff, &p, 1);
389 #endif
390 #ifdef CONFIG_SLIP_MODE_SLIP6
391         if (sl->mode & SL_MODE_SLIP6)
392                 count = slip_esc6(p, (unsigned char *) sl->xbuff, len);
393         else
394 #endif
395                 count = slip_esc(p, (unsigned char *) sl->xbuff, len);
396
397         /* Order of next two lines is *very* important.
398          * When we are sending a little amount of data,
399          * the transfer may be completed inside the ops->write()
400          * routine, because it's running with interrupts enabled.
401          * In this case we *never* got WRITE_WAKEUP event,
402          * if we did not request it before write operation.
403          *       14 Oct 1994  Dmitry Gorodchanin.
404          */
405         set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
406         actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
407 #ifdef SL_CHECK_TRANSMIT
408         sl->dev->trans_start = jiffies;
409 #endif
410         sl->xleft = count - actual;
411         sl->xhead = sl->xbuff + actual;
412 #ifdef CONFIG_SLIP_SMART
413         /* VSV */
414         clear_bit(SLF_OUTWAIT, &sl->flags);     /* reset outfill flag */
415 #endif
416 }
417
418 /*
419  * Called by the driver when there's room for more data.  If we have
420  * more packets to send, we send them here.
421  */
422 static void slip_write_wakeup(struct tty_struct *tty)
423 {
424         int actual;
425         struct slip *sl = tty->disc_data;
426
427         /* First make sure we're connected. */
428         if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
429                 return;
430
431         if (sl->xleft <= 0)  {
432                 /* Now serial buffer is almost free & we can start
433                  * transmission of another packet */
434                 sl->tx_packets++;
435                 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
436                 sl_unlock(sl);
437                 return;
438         }
439
440         actual = tty->ops->write(tty, sl->xhead, sl->xleft);
441         sl->xleft -= actual;
442         sl->xhead += actual;
443 }
444
445 static void sl_tx_timeout(struct net_device *dev)
446 {
447         struct slip *sl = netdev_priv(dev);
448
449         spin_lock(&sl->lock);
450
451         if (netif_queue_stopped(dev)) {
452                 if (!netif_running(dev))
453                         goto out;
454
455                 /* May be we must check transmitter timeout here ?
456                  *      14 Oct 1994 Dmitry Gorodchanin.
457                  */
458 #ifdef SL_CHECK_TRANSMIT
459                 if (time_before(jiffies, dev->trans_start + 20 * HZ))  {
460                         /* 20 sec timeout not reached */
461                         goto out;
462                 }
463                 printk(KERN_WARNING "%s: transmit timed out, %s?\n",
464                         dev->name,
465                         (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
466                                 "bad line quality" : "driver error");
467                 sl->xleft = 0;
468                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
469                 sl_unlock(sl);
470 #endif
471         }
472 out:
473         spin_unlock(&sl->lock);
474 }
475
476
477 /* Encapsulate an IP datagram and kick it into a TTY queue. */
478 static netdev_tx_t
479 sl_xmit(struct sk_buff *skb, struct net_device *dev)
480 {
481         struct slip *sl = netdev_priv(dev);
482
483         spin_lock(&sl->lock);
484         if (!netif_running(dev)) {
485                 spin_unlock(&sl->lock);
486                 printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name);
487                 dev_kfree_skb(skb);
488                 return NETDEV_TX_OK;
489         }
490         if (sl->tty == NULL) {
491                 spin_unlock(&sl->lock);
492                 dev_kfree_skb(skb);
493                 return NETDEV_TX_OK;
494         }
495
496         sl_lock(sl);
497         sl->tx_bytes += skb->len;
498         sl_encaps(sl, skb->data, skb->len);
499         spin_unlock(&sl->lock);
500
501         dev_kfree_skb(skb);
502         return NETDEV_TX_OK;
503 }
504
505
506 /******************************************
507  *   Routines looking at netdevice side.
508  ******************************************/
509
510 /* Netdevice UP -> DOWN routine */
511
512 static int
513 sl_close(struct net_device *dev)
514 {
515         struct slip *sl = netdev_priv(dev);
516
517         spin_lock_bh(&sl->lock);
518         if (sl->tty)
519                 /* TTY discipline is running. */
520                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
521         netif_stop_queue(dev);
522         sl->rcount   = 0;
523         sl->xleft    = 0;
524         spin_unlock_bh(&sl->lock);
525
526         return 0;
527 }
528
529 /* Netdevice DOWN -> UP routine */
530
531 static int sl_open(struct net_device *dev)
532 {
533         struct slip *sl = netdev_priv(dev);
534
535         if (sl->tty == NULL)
536                 return -ENODEV;
537
538         sl->flags &= (1 << SLF_INUSE);
539         netif_start_queue(dev);
540         return 0;
541 }
542
543 /* Netdevice change MTU request */
544
545 static int sl_change_mtu(struct net_device *dev, int new_mtu)
546 {
547         struct slip *sl = netdev_priv(dev);
548
549         if (new_mtu < 68 || new_mtu > 65534)
550                 return -EINVAL;
551
552         if (new_mtu != dev->mtu)
553                 return sl_realloc_bufs(sl, new_mtu);
554         return 0;
555 }
556
557 /* Netdevice get statistics request */
558
559 static struct net_device_stats *
560 sl_get_stats(struct net_device *dev)
561 {
562         static struct net_device_stats stats;
563         struct slip *sl = netdev_priv(dev);
564 #ifdef SL_INCLUDE_CSLIP
565         struct slcompress *comp;
566 #endif
567
568         memset(&stats, 0, sizeof(struct net_device_stats));
569
570         stats.rx_packets     = sl->rx_packets;
571         stats.tx_packets     = sl->tx_packets;
572         stats.rx_bytes       = sl->rx_bytes;
573         stats.tx_bytes       = sl->tx_bytes;
574         stats.rx_dropped     = sl->rx_dropped;
575         stats.tx_dropped     = sl->tx_dropped;
576         stats.tx_errors      = sl->tx_errors;
577         stats.rx_errors      = sl->rx_errors;
578         stats.rx_over_errors = sl->rx_over_errors;
579 #ifdef SL_INCLUDE_CSLIP
580         stats.rx_fifo_errors = sl->rx_compressed;
581         stats.tx_fifo_errors = sl->tx_compressed;
582         stats.collisions     = sl->tx_misses;
583         comp = sl->slcomp;
584         if (comp) {
585                 stats.rx_fifo_errors += comp->sls_i_compressed;
586                 stats.rx_dropped     += comp->sls_i_tossed;
587                 stats.tx_fifo_errors += comp->sls_o_compressed;
588                 stats.collisions     += comp->sls_o_misses;
589         }
590 #endif /* CONFIG_INET */
591         return (&stats);
592 }
593
594 /* Netdevice register callback */
595
596 static int sl_init(struct net_device *dev)
597 {
598         struct slip *sl = netdev_priv(dev);
599
600         /*
601          *      Finish setting up the DEVICE info.
602          */
603
604         dev->mtu                = sl->mtu;
605         dev->type               = ARPHRD_SLIP + sl->mode;
606 #ifdef SL_CHECK_TRANSMIT
607         dev->watchdog_timeo     = 20*HZ;
608 #endif
609         return 0;
610 }
611
612
613 static void sl_uninit(struct net_device *dev)
614 {
615         struct slip *sl = netdev_priv(dev);
616
617         sl_free_bufs(sl);
618 }
619
620 /* Hook the destructor so we can free slip devices at the right point in time */
621 static void sl_free_netdev(struct net_device *dev)
622 {
623         int i = dev->base_addr;
624         free_netdev(dev);
625         slip_devs[i] = NULL;
626 }
627
628 static const struct net_device_ops sl_netdev_ops = {
629         .ndo_init               = sl_init,
630         .ndo_uninit             = sl_uninit,
631         .ndo_open               = sl_open,
632         .ndo_stop               = sl_close,
633         .ndo_start_xmit         = sl_xmit,
634         .ndo_get_stats          = sl_get_stats,
635         .ndo_change_mtu         = sl_change_mtu,
636         .ndo_tx_timeout         = sl_tx_timeout,
637 #ifdef CONFIG_SLIP_SMART
638         .ndo_do_ioctl           = sl_ioctl,
639 #endif
640 };
641
642
643 static void sl_setup(struct net_device *dev)
644 {
645         dev->netdev_ops         = &sl_netdev_ops;
646         dev->destructor         = sl_free_netdev;
647
648         dev->hard_header_len    = 0;
649         dev->addr_len           = 0;
650         dev->tx_queue_len       = 10;
651
652         /* New-style flags. */
653         dev->flags              = IFF_NOARP|IFF_POINTOPOINT|IFF_MULTICAST;
654 }
655
656 /******************************************
657   Routines looking at TTY side.
658  ******************************************/
659
660
661 /*
662  * Handle the 'receiver data ready' interrupt.
663  * This function is called by the 'tty_io' module in the kernel when
664  * a block of SLIP data has been received, which can now be decapsulated
665  * and sent on to some IP layer for further processing. This will not
666  * be re-entered while running but other ldisc functions may be called
667  * in parallel
668  */
669
670 static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp,
671                                                         char *fp, int count)
672 {
673         struct slip *sl = tty->disc_data;
674
675         if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
676                 return;
677
678         /* Read the characters out of the buffer */
679         while (count--) {
680                 if (fp && *fp++) {
681                         if (!test_and_set_bit(SLF_ERROR, &sl->flags))
682                                 sl->rx_errors++;
683                         cp++;
684                         continue;
685                 }
686 #ifdef CONFIG_SLIP_MODE_SLIP6
687                 if (sl->mode & SL_MODE_SLIP6)
688                         slip_unesc6(sl, *cp++);
689                 else
690 #endif
691                         slip_unesc(sl, *cp++);
692         }
693 }
694
695 /************************************
696  *  slip_open helper routines.
697  ************************************/
698
699 /* Collect hanged up channels */
700 static void sl_sync(void)
701 {
702         int i;
703         struct net_device *dev;
704         struct slip       *sl;
705
706         for (i = 0; i < slip_maxdev; i++) {
707                 dev = slip_devs[i];
708                 if (dev == NULL)
709                         break;
710
711                 sl = netdev_priv(dev);
712                 if (sl->tty || sl->leased)
713                         continue;
714                 if (dev->flags & IFF_UP)
715                         dev_close(dev);
716         }
717 }
718
719
720 /* Find a free SLIP channel, and link in this `tty' line. */
721 static struct slip *sl_alloc(dev_t line)
722 {
723         int i;
724         struct net_device *dev = NULL;
725         struct slip       *sl;
726
727         if (slip_devs == NULL)
728                 return NULL;    /* Master array missing ! */
729
730         for (i = 0; i < slip_maxdev; i++) {
731                 dev = slip_devs[i];
732                 if (dev == NULL)
733                         break;
734         }
735         /* Sorry, too many, all slots in use */
736         if (i >= slip_maxdev)
737                 return NULL;
738
739         if (dev) {
740                 sl = netdev_priv(dev);
741                 if (test_bit(SLF_INUSE, &sl->flags)) {
742                         unregister_netdevice(dev);
743                         dev = NULL;
744                         slip_devs[i] = NULL;
745                 }
746         }
747
748         if (!dev) {
749                 char name[IFNAMSIZ];
750                 sprintf(name, "sl%d", i);
751
752                 dev = alloc_netdev(sizeof(*sl), name, sl_setup);
753                 if (!dev)
754                         return NULL;
755                 dev->base_addr  = i;
756         }
757
758         sl = netdev_priv(dev);
759
760         /* Initialize channel control data */
761         sl->magic       = SLIP_MAGIC;
762         sl->dev         = dev;
763         spin_lock_init(&sl->lock);
764         sl->mode        = SL_MODE_DEFAULT;
765 #ifdef CONFIG_SLIP_SMART
766         /* initialize timer_list struct */
767         init_timer(&sl->keepalive_timer);
768         sl->keepalive_timer.data = (unsigned long)sl;
769         sl->keepalive_timer.function = sl_keepalive;
770         init_timer(&sl->outfill_timer);
771         sl->outfill_timer.data = (unsigned long)sl;
772         sl->outfill_timer.function = sl_outfill;
773 #endif
774         slip_devs[i] = dev;
775         return sl;
776 }
777
778 /*
779  * Open the high-level part of the SLIP channel.
780  * This function is called by the TTY module when the
781  * SLIP line discipline is called for.  Because we are
782  * sure the tty line exists, we only have to link it to
783  * a free SLIP channel...
784  *
785  * Called in process context serialized from other ldisc calls.
786  */
787
788 static int slip_open(struct tty_struct *tty)
789 {
790         struct slip *sl;
791         int err;
792
793         if (!capable(CAP_NET_ADMIN))
794                 return -EPERM;
795
796         if (tty->ops->write == NULL)
797                 return -EOPNOTSUPP;
798
799         /* RTnetlink lock is misused here to serialize concurrent
800            opens of slip channels. There are better ways, but it is
801            the simplest one.
802          */
803         rtnl_lock();
804
805         /* Collect hanged up channels. */
806         sl_sync();
807
808         sl = tty->disc_data;
809
810         err = -EEXIST;
811         /* First make sure we're not already connected. */
812         if (sl && sl->magic == SLIP_MAGIC)
813                 goto err_exit;
814
815         /* OK.  Find a free SLIP channel to use. */
816         err = -ENFILE;
817         sl = sl_alloc(tty_devnum(tty));
818         if (sl == NULL)
819                 goto err_exit;
820
821         sl->tty = tty;
822         tty->disc_data = sl;
823         sl->line = tty_devnum(tty);
824         sl->pid = current->pid;
825
826         if (!test_bit(SLF_INUSE, &sl->flags)) {
827                 /* Perform the low-level SLIP initialization. */
828                 err = sl_alloc_bufs(sl, SL_MTU);
829                 if (err)
830                         goto err_free_chan;
831
832                 set_bit(SLF_INUSE, &sl->flags);
833
834                 err = register_netdevice(sl->dev);
835                 if (err)
836                         goto err_free_bufs;
837         }
838
839 #ifdef CONFIG_SLIP_SMART
840         if (sl->keepalive) {
841                 sl->keepalive_timer.expires = jiffies + sl->keepalive * HZ;
842                 add_timer(&sl->keepalive_timer);
843         }
844         if (sl->outfill) {
845                 sl->outfill_timer.expires = jiffies + sl->outfill * HZ;
846                 add_timer(&sl->outfill_timer);
847         }
848 #endif
849
850         /* Done.  We have linked the TTY line to a channel. */
851         rtnl_unlock();
852         tty->receive_room = 65536;      /* We don't flow control */
853         return sl->dev->base_addr;
854
855 err_free_bufs:
856         sl_free_bufs(sl);
857
858 err_free_chan:
859         sl->tty = NULL;
860         tty->disc_data = NULL;
861         clear_bit(SLF_INUSE, &sl->flags);
862
863 err_exit:
864         rtnl_unlock();
865
866         /* Count references from TTY module */
867         return err;
868 }
869
870 /*
871  * Close down a SLIP channel.
872  * This means flushing out any pending queues, and then returning. This
873  * call is serialized against other ldisc functions.
874  *
875  * We also use this method fo a hangup event
876  */
877
878 static void slip_close(struct tty_struct *tty)
879 {
880         struct slip *sl = tty->disc_data;
881
882         /* First make sure we're connected. */
883         if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty)
884                 return;
885
886         tty->disc_data = NULL;
887         sl->tty = NULL;
888         if (!sl->leased)
889                 sl->line = 0;
890
891         /* VSV = very important to remove timers */
892 #ifdef CONFIG_SLIP_SMART
893         del_timer_sync(&sl->keepalive_timer);
894         del_timer_sync(&sl->outfill_timer);
895 #endif
896         /* Flush network side */
897         unregister_netdev(sl->dev);
898         /* This will complete via sl_free_netdev */
899 }
900
901 static int slip_hangup(struct tty_struct *tty)
902 {
903         slip_close(tty);
904         return 0;
905 }
906  /************************************************************************
907   *                     STANDARD SLIP ENCAPSULATION                      *
908   ************************************************************************/
909
910 static int slip_esc(unsigned char *s, unsigned char *d, int len)
911 {
912         unsigned char *ptr = d;
913         unsigned char c;
914
915         /*
916          * Send an initial END character to flush out any
917          * data that may have accumulated in the receiver
918          * due to line noise.
919          */
920
921         *ptr++ = END;
922
923         /*
924          * For each byte in the packet, send the appropriate
925          * character sequence, according to the SLIP protocol.
926          */
927
928         while (len-- > 0) {
929                 switch (c = *s++) {
930                 case END:
931                         *ptr++ = ESC;
932                         *ptr++ = ESC_END;
933                         break;
934                 case ESC:
935                         *ptr++ = ESC;
936                         *ptr++ = ESC_ESC;
937                         break;
938                 default:
939                         *ptr++ = c;
940                         break;
941                 }
942         }
943         *ptr++ = END;
944         return (ptr - d);
945 }
946
947 static void slip_unesc(struct slip *sl, unsigned char s)
948 {
949
950         switch (s) {
951         case END:
952 #ifdef CONFIG_SLIP_SMART
953                 /* drop keeptest bit = VSV */
954                 if (test_bit(SLF_KEEPTEST, &sl->flags))
955                         clear_bit(SLF_KEEPTEST, &sl->flags);
956 #endif
957
958                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags)
959                                                         && (sl->rcount > 2))
960                         sl_bump(sl);
961                 clear_bit(SLF_ESCAPE, &sl->flags);
962                 sl->rcount = 0;
963                 return;
964
965         case ESC:
966                 set_bit(SLF_ESCAPE, &sl->flags);
967                 return;
968         case ESC_ESC:
969                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
970                         s = ESC;
971                 break;
972         case ESC_END:
973                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
974                         s = END;
975                 break;
976         }
977         if (!test_bit(SLF_ERROR, &sl->flags))  {
978                 if (sl->rcount < sl->buffsize)  {
979                         sl->rbuff[sl->rcount++] = s;
980                         return;
981                 }
982                 sl->rx_over_errors++;
983                 set_bit(SLF_ERROR, &sl->flags);
984         }
985 }
986
987
988 #ifdef CONFIG_SLIP_MODE_SLIP6
989 /************************************************************************
990  *                       6 BIT SLIP ENCAPSULATION                       *
991  ************************************************************************/
992
993 static int slip_esc6(unsigned char *s, unsigned char *d, int len)
994 {
995         unsigned char *ptr = d;
996         unsigned char c;
997         int i;
998         unsigned short v = 0;
999         short bits = 0;
1000
1001         /*
1002          * Send an initial END character to flush out any
1003          * data that may have accumulated in the receiver
1004          * due to line noise.
1005          */
1006
1007         *ptr++ = 0x70;
1008
1009         /*
1010          * Encode the packet into printable ascii characters
1011          */
1012
1013         for (i = 0; i < len; ++i) {
1014                 v = (v << 8) | s[i];
1015                 bits += 8;
1016                 while (bits >= 6) {
1017                         bits -= 6;
1018                         c = 0x30 + ((v >> bits) & 0x3F);
1019                         *ptr++ = c;
1020                 }
1021         }
1022         if (bits) {
1023                 c = 0x30 + ((v << (6 - bits)) & 0x3F);
1024                 *ptr++ = c;
1025         }
1026         *ptr++ = 0x70;
1027         return ptr - d;
1028 }
1029
1030 static void slip_unesc6(struct slip *sl, unsigned char s)
1031 {
1032         unsigned char c;
1033
1034         if (s == 0x70) {
1035 #ifdef CONFIG_SLIP_SMART
1036                 /* drop keeptest bit = VSV */
1037                 if (test_bit(SLF_KEEPTEST, &sl->flags))
1038                         clear_bit(SLF_KEEPTEST, &sl->flags);
1039 #endif
1040
1041                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags)
1042                                                         && (sl->rcount > 2))
1043                         sl_bump(sl);
1044                 sl->rcount = 0;
1045                 sl->xbits = 0;
1046                 sl->xdata = 0;
1047         } else if (s >= 0x30 && s < 0x70) {
1048                 sl->xdata = (sl->xdata << 6) | ((s - 0x30) & 0x3F);
1049                 sl->xbits += 6;
1050                 if (sl->xbits >= 8) {
1051                         sl->xbits -= 8;
1052                         c = (unsigned char)(sl->xdata >> sl->xbits);
1053                         if (!test_bit(SLF_ERROR, &sl->flags))  {
1054                                 if (sl->rcount < sl->buffsize)  {
1055                                         sl->rbuff[sl->rcount++] = c;
1056                                         return;
1057                                 }
1058                                 sl->rx_over_errors++;
1059                                 set_bit(SLF_ERROR, &sl->flags);
1060                         }
1061                 }
1062         }
1063 }
1064 #endif /* CONFIG_SLIP_MODE_SLIP6 */
1065
1066 /* Perform I/O control on an active SLIP channel. */
1067 static int slip_ioctl(struct tty_struct *tty, struct file *file,
1068                                         unsigned int cmd, unsigned long arg)
1069 {
1070         struct slip *sl = tty->disc_data;
1071         unsigned int tmp;
1072         int __user *p = (int __user *)arg;
1073
1074         /* First make sure we're connected. */
1075         if (!sl || sl->magic != SLIP_MAGIC)
1076                 return -EINVAL;
1077
1078         switch (cmd) {
1079         case SIOCGIFNAME:
1080                 tmp = strlen(sl->dev->name) + 1;
1081                 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
1082                         return -EFAULT;
1083                 return 0;
1084
1085         case SIOCGIFENCAP:
1086                 if (put_user(sl->mode, p))
1087                         return -EFAULT;
1088                 return 0;
1089
1090         case SIOCSIFENCAP:
1091                 if (get_user(tmp, p))
1092                         return -EFAULT;
1093 #ifndef SL_INCLUDE_CSLIP
1094                 if (tmp & (SL_MODE_CSLIP|SL_MODE_ADAPTIVE))
1095                         return -EINVAL;
1096 #else
1097                 if ((tmp & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) ==
1098                     (SL_MODE_ADAPTIVE | SL_MODE_CSLIP))
1099                         /* return -EINVAL; */
1100                         tmp &= ~SL_MODE_ADAPTIVE;
1101 #endif
1102 #ifndef CONFIG_SLIP_MODE_SLIP6
1103                 if (tmp & SL_MODE_SLIP6)
1104                         return -EINVAL;
1105 #endif
1106                 sl->mode = tmp;
1107                 sl->dev->type = ARPHRD_SLIP + sl->mode;
1108                 return 0;
1109
1110         case SIOCSIFHWADDR:
1111                 return -EINVAL;
1112
1113 #ifdef CONFIG_SLIP_SMART
1114         /* VSV changes start here */
1115         case SIOCSKEEPALIVE:
1116                 if (get_user(tmp, p))
1117                         return -EFAULT;
1118                 if (tmp > 255) /* max for unchar */
1119                         return -EINVAL;
1120
1121                 spin_lock_bh(&sl->lock);
1122                 if (!sl->tty) {
1123                         spin_unlock_bh(&sl->lock);
1124                         return -ENODEV;
1125                 }
1126                 sl->keepalive = (u8)tmp;
1127                 if (sl->keepalive != 0) {
1128                         mod_timer(&sl->keepalive_timer,
1129                                         jiffies + sl->keepalive * HZ);
1130                         set_bit(SLF_KEEPTEST, &sl->flags);
1131                 } else
1132                         del_timer(&sl->keepalive_timer);
1133                 spin_unlock_bh(&sl->lock);
1134                 return 0;
1135
1136         case SIOCGKEEPALIVE:
1137                 if (put_user(sl->keepalive, p))
1138                         return -EFAULT;
1139                 return 0;
1140
1141         case SIOCSOUTFILL:
1142                 if (get_user(tmp, p))
1143                         return -EFAULT;
1144                 if (tmp > 255) /* max for unchar */
1145                         return -EINVAL;
1146                 spin_lock_bh(&sl->lock);
1147                 if (!sl->tty) {
1148                         spin_unlock_bh(&sl->lock);
1149                         return -ENODEV;
1150                 }
1151                 sl->outfill = (u8)tmp;
1152                 if (sl->outfill != 0) {
1153                         mod_timer(&sl->outfill_timer,
1154                                                 jiffies + sl->outfill * HZ);
1155                         set_bit(SLF_OUTWAIT, &sl->flags);
1156                 } else
1157                         del_timer(&sl->outfill_timer);
1158                 spin_unlock_bh(&sl->lock);
1159                 return 0;
1160
1161         case SIOCGOUTFILL:
1162                 if (put_user(sl->outfill, p))
1163                         return -EFAULT;
1164                 return 0;
1165         /* VSV changes end */
1166 #endif
1167         default:
1168                 return tty_mode_ioctl(tty, file, cmd, arg);
1169         }
1170 }
1171
1172 #ifdef CONFIG_COMPAT
1173 static long slip_compat_ioctl(struct tty_struct *tty, struct file *file,
1174                                         unsigned int cmd, unsigned long arg)
1175 {
1176         switch (cmd) {
1177         case SIOCGIFNAME:
1178         case SIOCGIFENCAP:
1179         case SIOCSIFENCAP:
1180         case SIOCSIFHWADDR:
1181         case SIOCSKEEPALIVE:
1182         case SIOCGKEEPALIVE:
1183         case SIOCSOUTFILL:
1184         case SIOCGOUTFILL:
1185                 return slip_ioctl(tty, file, cmd,
1186                                   (unsigned long)compat_ptr(arg));
1187         }
1188
1189         return -ENOIOCTLCMD;
1190 }
1191 #endif
1192
1193 /* VSV changes start here */
1194 #ifdef CONFIG_SLIP_SMART
1195 /* function do_ioctl called from net/core/dev.c
1196    to allow get/set outfill/keepalive parameter
1197    by ifconfig                                 */
1198
1199 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
1200 {
1201         struct slip *sl = netdev_priv(dev);
1202         unsigned long *p = (unsigned long *)&rq->ifr_ifru;
1203
1204         if (sl == NULL)         /* Allocation failed ?? */
1205                 return -ENODEV;
1206
1207         spin_lock_bh(&sl->lock);
1208
1209         if (!sl->tty) {
1210                 spin_unlock_bh(&sl->lock);
1211                 return -ENODEV;
1212         }
1213
1214         switch (cmd) {
1215         case SIOCSKEEPALIVE:
1216                 /* max for unchar */
1217                 if ((unsigned)*p > 255) {
1218                         spin_unlock_bh(&sl->lock);
1219                         return -EINVAL;
1220                 }
1221                 sl->keepalive = (u8)*p;
1222                 if (sl->keepalive != 0) {
1223                         sl->keepalive_timer.expires =
1224                                                 jiffies + sl->keepalive * HZ;
1225                         mod_timer(&sl->keepalive_timer,
1226                                                 jiffies + sl->keepalive * HZ);
1227                         set_bit(SLF_KEEPTEST, &sl->flags);
1228                 } else
1229                         del_timer(&sl->keepalive_timer);
1230                 break;
1231
1232         case SIOCGKEEPALIVE:
1233                 *p = sl->keepalive;
1234                 break;
1235
1236         case SIOCSOUTFILL:
1237                 if ((unsigned)*p > 255) { /* max for unchar */
1238                         spin_unlock_bh(&sl->lock);
1239                         return -EINVAL;
1240                 }
1241                 sl->outfill = (u8)*p;
1242                 if (sl->outfill != 0) {
1243                         mod_timer(&sl->outfill_timer,
1244                                                 jiffies + sl->outfill * HZ);
1245                         set_bit(SLF_OUTWAIT, &sl->flags);
1246                 } else
1247                         del_timer(&sl->outfill_timer);
1248                 break;
1249
1250         case SIOCGOUTFILL:
1251                 *p = sl->outfill;
1252                 break;
1253
1254         case SIOCSLEASE:
1255                 /* Resolve race condition, when ioctl'ing hanged up
1256                    and opened by another process device.
1257                  */
1258                 if (sl->tty != current->signal->tty &&
1259                                                 sl->pid != current->pid) {
1260                         spin_unlock_bh(&sl->lock);
1261                         return -EPERM;
1262                 }
1263                 sl->leased = 0;
1264                 if (*p)
1265                         sl->leased = 1;
1266                 break;
1267
1268         case SIOCGLEASE:
1269                 *p = sl->leased;
1270         };
1271         spin_unlock_bh(&sl->lock);
1272         return 0;
1273 }
1274 #endif
1275 /* VSV changes end */
1276
1277 static struct tty_ldisc_ops sl_ldisc = {
1278         .owner          = THIS_MODULE,
1279         .magic          = TTY_LDISC_MAGIC,
1280         .name           = "slip",
1281         .open           = slip_open,
1282         .close          = slip_close,
1283         .hangup         = slip_hangup,
1284         .ioctl          = slip_ioctl,
1285 #ifdef CONFIG_COMPAT
1286         .compat_ioctl   = slip_compat_ioctl,
1287 #endif
1288         .receive_buf    = slip_receive_buf,
1289         .write_wakeup   = slip_write_wakeup,
1290 };
1291
1292 static int __init slip_init(void)
1293 {
1294         int status;
1295
1296         if (slip_maxdev < 4)
1297                 slip_maxdev = 4; /* Sanity */
1298
1299         printk(KERN_INFO "SLIP: version %s (dynamic channels, max=%d)"
1300 #ifdef CONFIG_SLIP_MODE_SLIP6
1301                " (6 bit encapsulation enabled)"
1302 #endif
1303                ".\n",
1304                SLIP_VERSION, slip_maxdev);
1305 #if defined(SL_INCLUDE_CSLIP)
1306         printk(KERN_INFO "CSLIP: code copyright 1989 Regents of the University of California.\n");
1307 #endif
1308 #ifdef CONFIG_SLIP_SMART
1309         printk(KERN_INFO "SLIP linefill/keepalive option.\n");
1310 #endif
1311
1312         slip_devs = kzalloc(sizeof(struct net_device *)*slip_maxdev,
1313                                                                 GFP_KERNEL);
1314         if (!slip_devs) {
1315                 printk(KERN_ERR "SLIP: Can't allocate slip devices array.\n");
1316                 return -ENOMEM;
1317         }
1318
1319         /* Fill in our line protocol discipline, and register it */
1320         status = tty_register_ldisc(N_SLIP, &sl_ldisc);
1321         if (status != 0) {
1322                 printk(KERN_ERR "SLIP: can't register line discipline (err = %d)\n", status);
1323                 kfree(slip_devs);
1324         }
1325         return status;
1326 }
1327
1328 static void __exit slip_exit(void)
1329 {
1330         int i;
1331         struct net_device *dev;
1332         struct slip *sl;
1333         unsigned long timeout = jiffies + HZ;
1334         int busy = 0;
1335
1336         if (slip_devs == NULL)
1337                 return;
1338
1339         /* First of all: check for active disciplines and hangup them.
1340          */
1341         do {
1342                 if (busy)
1343                         msleep_interruptible(100);
1344
1345                 busy = 0;
1346                 for (i = 0; i < slip_maxdev; i++) {
1347                         dev = slip_devs[i];
1348                         if (!dev)
1349                                 continue;
1350                         sl = netdev_priv(dev);
1351                         spin_lock_bh(&sl->lock);
1352                         if (sl->tty) {
1353                                 busy++;
1354                                 tty_hangup(sl->tty);
1355                         }
1356                         spin_unlock_bh(&sl->lock);
1357                 }
1358         } while (busy && time_before(jiffies, timeout));
1359
1360         /* FIXME: hangup is async so we should wait when doing this second
1361            phase */
1362
1363         for (i = 0; i < slip_maxdev; i++) {
1364                 dev = slip_devs[i];
1365                 if (!dev)
1366                         continue;
1367                 slip_devs[i] = NULL;
1368
1369                 sl = netdev_priv(dev);
1370                 if (sl->tty) {
1371                         printk(KERN_ERR "%s: tty discipline still running\n",
1372                                dev->name);
1373                         /* Intentionally leak the control block. */
1374                         dev->destructor = NULL;
1375                 }
1376
1377                 unregister_netdev(dev);
1378         }
1379
1380         kfree(slip_devs);
1381         slip_devs = NULL;
1382
1383         i = tty_unregister_ldisc(N_SLIP);
1384         if (i != 0)
1385                 printk(KERN_ERR "SLIP: can't unregister line discipline (err = %d)\n", i);
1386 }
1387
1388 module_init(slip_init);
1389 module_exit(slip_exit);
1390
1391 #ifdef CONFIG_SLIP_SMART
1392 /*
1393  * This is start of the code for multislip style line checking
1394  * added by Stanislav Voronyi. All changes before marked VSV
1395  */
1396
1397 static void sl_outfill(unsigned long sls)
1398 {
1399         struct slip *sl = (struct slip *)sls;
1400
1401         spin_lock(&sl->lock);
1402
1403         if (sl->tty == NULL)
1404                 goto out;
1405
1406         if (sl->outfill) {
1407                 if (test_bit(SLF_OUTWAIT, &sl->flags)) {
1408                         /* no packets were transmitted, do outfill */
1409 #ifdef CONFIG_SLIP_MODE_SLIP6
1410                         unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END;
1411 #else
1412                         unsigned char s = END;
1413 #endif
1414                         /* put END into tty queue. Is it right ??? */
1415                         if (!netif_queue_stopped(sl->dev)) {
1416                                 /* if device busy no outfill */
1417                                 sl->tty->ops->write(sl->tty, &s, 1);
1418                         }
1419                 } else
1420                         set_bit(SLF_OUTWAIT, &sl->flags);
1421
1422                 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
1423         }
1424 out:
1425         spin_unlock(&sl->lock);
1426 }
1427
1428 static void sl_keepalive(unsigned long sls)
1429 {
1430         struct slip *sl = (struct slip *)sls;
1431
1432         spin_lock(&sl->lock);
1433
1434         if (sl->tty == NULL)
1435                 goto out;
1436
1437         if (sl->keepalive) {
1438                 if (test_bit(SLF_KEEPTEST, &sl->flags)) {
1439                         /* keepalive still high :(, we must hangup */
1440                         if (sl->outfill)
1441                                 /* outfill timer must be deleted too */
1442                                 (void)del_timer(&sl->outfill_timer);
1443                         printk(KERN_DEBUG "%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name);
1444                         /* this must hangup tty & close slip */
1445                         tty_hangup(sl->tty);
1446                         /* I think we need not something else */
1447                         goto out;
1448                 } else
1449                         set_bit(SLF_KEEPTEST, &sl->flags);
1450
1451                 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
1452         }
1453 out:
1454         spin_unlock(&sl->lock);
1455 }
1456
1457 #endif
1458 MODULE_LICENSE("GPL");
1459 MODULE_ALIAS_LDISC(N_SLIP);