ia64/linux-2.6.18-xen.hg

view drivers/net/slip.c @ 897:329ea0ccb344

balloon: try harder to balloon up under memory pressure.

Currently if the balloon driver is unable to increase the guest's
reservation it assumes the failure was due to reaching its full
allocation, gives up on the ballooning operation and records the limit
it reached as the "hard limit". The driver will not try again until
the target is set again (even to the same value).

However it is possible that ballooning has in fact failed due to
memory pressure in the host and therefore it is desirable to keep
attempting to reach the target in case memory becomes available. The
most likely scenario is that some guests are ballooning down while
others are ballooning up and therefore there is temporary memory
pressure while things stabilise. You would not expect a well behaved
toolstack to ask a domain to balloon to more than its allocation nor
would you expect it to deliberately over-commit memory by setting
balloon targets which exceed the total host memory.

This patch drops the concept of a hard limit and causes the balloon
driver to retry increasing the reservation on a timer in the same
manner as when decreasing the reservation.

Also if we partially succeed in increasing the reservation
(i.e. receive less pages than we asked for) then we may as well keep
those pages rather than returning them to Xen.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Fri Jun 05 14:01:20 2009 +0100 (2009-06-05)
parents 831230e53067
children
line source
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 mtu upwards.
15 * Driver now spots this and grows/shrinks its buffers(hack!).
16 * Memory leak if you run out of memory setting up a slip driver fixed.
17 * Matt Dillon : Printable slip (borrowed from NET2E)
18 * Pauline Middelink : Slip driver fixes.
19 * Alan Cox : Honours the old SL_COMPRESSED flag
20 * Alan Cox : KISS AX.25 and AXUI IP support
21 * Michael Riepe : Automatic CSLIP recognition added
22 * Charles Hedrick : CSLIP header length problem fix.
23 * Alan Cox : Corrected non-IP cases of the above.
24 * Alan Cox : Now uses hardware type as per FvK.
25 * Alan Cox : Default to 192.168.0.0 (RFC 1597)
26 * A.N.Kuznetsov : dev_tint() recursion fix.
27 * Dmitry Gorodchanin : SLIP memory leaks
28 * Dmitry Gorodchanin : Code cleanup. Reduce tty driver
29 * buffering from 4096 to 256 bytes.
30 * Improving SLIP response time.
31 * CONFIG_SLIP_MODE_SLIP6.
32 * ifconfig sl? up & down now works correctly.
33 * Modularization.
34 * Alan Cox : Oops - fix AX.25 buffer lengths
35 * Dmitry Gorodchanin : Even more cleanups. Preserve CSLIP
36 * statistics. Include CSLIP code only
37 * if it really needed.
38 * Alan Cox : Free slhc buffers in the right place.
39 * Alan Cox : Allow for digipeated IP over AX.25
40 * Matti Aarnio : Dynamic SLIP devices, with ideas taken
41 * from Jim Freeman's <jfree@caldera.com>
42 * dynamic PPP devices. We do NOT kfree()
43 * device entries, just reg./unreg. them
44 * as they are needed. We kfree() them
45 * at module cleanup.
46 * With MODULE-loading ``insmod'', user can
47 * issue parameter: slip_maxdev=1024
48 * (Or how much he/she wants.. Default is 256)
49 * * Stanislav Voronyi : Slip line checking, with ideas taken
50 * from multislip BSDI driver which was written
51 * by Igor Chechik, RELCOM Corp. Only algorithms
52 * have been ported to Linux SLIP driver.
53 * Vitaly E. Lavrov : Sane behaviour on tty hangup.
54 * Alexey Kuznetsov : Cleanup interfaces to tty&netdevice modules.
55 */
57 #define SL_CHECK_TRANSMIT
58 #include <linux/module.h>
59 #include <linux/moduleparam.h>
61 #include <asm/system.h>
62 #include <asm/uaccess.h>
63 #include <linux/bitops.h>
64 #include <linux/string.h>
65 #include <linux/mm.h>
66 #include <linux/interrupt.h>
67 #include <linux/in.h>
68 #include <linux/tty.h>
69 #include <linux/errno.h>
70 #include <linux/netdevice.h>
71 #include <linux/etherdevice.h>
72 #include <linux/skbuff.h>
73 #include <linux/rtnetlink.h>
74 #include <linux/if_arp.h>
75 #include <linux/if_slip.h>
76 #include <linux/delay.h>
77 #include <linux/init.h>
78 #include "slip.h"
79 #ifdef CONFIG_INET
80 #include <linux/ip.h>
81 #include <linux/tcp.h>
82 #include <net/slhc_vj.h>
83 #endif
85 #define SLIP_VERSION "0.8.4-NET3.019-NEWTTY"
87 static struct net_device **slip_devs;
89 static int slip_maxdev = SL_NRUNIT;
90 module_param(slip_maxdev, int, 0);
91 MODULE_PARM_DESC(slip_maxdev, "Maximum number of slip devices");
93 static int slip_esc(unsigned char *p, unsigned char *d, int len);
94 static void slip_unesc(struct slip *sl, unsigned char c);
95 #ifdef CONFIG_SLIP_MODE_SLIP6
96 static int slip_esc6(unsigned char *p, unsigned char *d, int len);
97 static void slip_unesc6(struct slip *sl, unsigned char c);
98 #endif
99 #ifdef CONFIG_SLIP_SMART
100 static void sl_keepalive(unsigned long sls);
101 static void sl_outfill(unsigned long sls);
102 static int sl_ioctl(struct net_device *dev,struct ifreq *rq,int cmd);
103 #endif
105 /********************************
106 * Buffer administration routines:
107 * sl_alloc_bufs()
108 * sl_free_bufs()
109 * sl_realloc_bufs()
110 *
111 * NOTE: sl_realloc_bufs != sl_free_bufs + sl_alloc_bufs, because
112 * sl_realloc_bufs provides strong atomicity and reallocation
113 * on actively running device.
114 *********************************/
116 /*
117 Allocate channel buffers.
118 */
120 static int
121 sl_alloc_bufs(struct slip *sl, int mtu)
122 {
123 int err = -ENOBUFS;
124 unsigned long len;
125 char * rbuff = NULL;
126 char * xbuff = NULL;
127 #ifdef SL_INCLUDE_CSLIP
128 char * cbuff = NULL;
129 struct slcompress *slcomp = NULL;
130 #endif
132 /*
133 * Allocate the SLIP frame buffers:
134 *
135 * rbuff Receive buffer.
136 * xbuff Transmit buffer.
137 * cbuff Temporary compression buffer.
138 */
139 len = mtu * 2;
141 /*
142 * allow for arrival of larger UDP packets, even if we say not to
143 * also fixes a bug in which SunOS sends 512-byte packets even with
144 * an MSS of 128
145 */
146 if (len < 576 * 2)
147 len = 576 * 2;
148 rbuff = kmalloc(len + 4, GFP_KERNEL);
149 if (rbuff == NULL)
150 goto err_exit;
151 xbuff = kmalloc(len + 4, GFP_KERNEL);
152 if (xbuff == NULL)
153 goto err_exit;
154 #ifdef SL_INCLUDE_CSLIP
155 cbuff = kmalloc(len + 4, GFP_KERNEL);
156 if (cbuff == NULL)
157 goto err_exit;
158 slcomp = slhc_init(16, 16);
159 if (slcomp == NULL)
160 goto err_exit;
161 #endif
162 spin_lock_bh(&sl->lock);
163 if (sl->tty == NULL) {
164 spin_unlock_bh(&sl->lock);
165 err = -ENODEV;
166 goto err_exit;
167 }
168 sl->mtu = mtu;
169 sl->buffsize = len;
170 sl->rcount = 0;
171 sl->xleft = 0;
172 rbuff = xchg(&sl->rbuff, rbuff);
173 xbuff = xchg(&sl->xbuff, xbuff);
174 #ifdef SL_INCLUDE_CSLIP
175 cbuff = xchg(&sl->cbuff, cbuff);
176 slcomp = xchg(&sl->slcomp, slcomp);
177 #ifdef CONFIG_SLIP_MODE_SLIP6
178 sl->xdata = 0;
179 sl->xbits = 0;
180 #endif
181 #endif
182 spin_unlock_bh(&sl->lock);
183 err = 0;
185 /* Cleanup */
186 err_exit:
187 #ifdef SL_INCLUDE_CSLIP
188 kfree(cbuff);
189 if (slcomp)
190 slhc_free(slcomp);
191 #endif
192 kfree(xbuff);
193 kfree(rbuff);
194 return err;
195 }
197 /* Free a SLIP channel buffers. */
198 static void
199 sl_free_bufs(struct slip *sl)
200 {
201 /* Free all SLIP frame buffers. */
202 kfree(xchg(&sl->rbuff, NULL));
203 kfree(xchg(&sl->xbuff, NULL));
204 #ifdef SL_INCLUDE_CSLIP
205 kfree(xchg(&sl->cbuff, NULL));
206 slhc_free(xchg(&sl->slcomp, NULL));
207 #endif
208 }
210 /*
211 Reallocate slip channel buffers.
212 */
214 static int sl_realloc_bufs(struct slip *sl, int mtu)
215 {
216 int err = 0;
217 struct net_device *dev = sl->dev;
218 unsigned char *xbuff, *rbuff;
219 #ifdef SL_INCLUDE_CSLIP
220 unsigned char *cbuff;
221 #endif
222 int len = mtu * 2;
224 /*
225 * allow for arrival of larger UDP packets, even if we say not to
226 * also fixes a bug in which SunOS sends 512-byte packets even with
227 * an MSS of 128
228 */
229 if (len < 576 * 2)
230 len = 576 * 2;
232 xbuff = (unsigned char *) kmalloc (len + 4, GFP_ATOMIC);
233 rbuff = (unsigned char *) kmalloc (len + 4, GFP_ATOMIC);
234 #ifdef SL_INCLUDE_CSLIP
235 cbuff = (unsigned char *) kmalloc (len + 4, GFP_ATOMIC);
236 #endif
239 #ifdef SL_INCLUDE_CSLIP
240 if (xbuff == NULL || rbuff == NULL || cbuff == NULL) {
241 #else
242 if (xbuff == NULL || rbuff == NULL) {
243 #endif
244 if (mtu >= sl->mtu) {
245 printk(KERN_WARNING "%s: unable to grow slip buffers, MTU change cancelled.\n",
246 dev->name);
247 err = -ENOBUFS;
248 }
249 goto done;
250 }
252 spin_lock_bh(&sl->lock);
254 err = -ENODEV;
255 if (sl->tty == NULL)
256 goto done_on_bh;
258 xbuff = xchg(&sl->xbuff, xbuff);
259 rbuff = xchg(&sl->rbuff, rbuff);
260 #ifdef SL_INCLUDE_CSLIP
261 cbuff = xchg(&sl->cbuff, cbuff);
262 #endif
263 if (sl->xleft) {
264 if (sl->xleft <= len) {
265 memcpy(sl->xbuff, sl->xhead, sl->xleft);
266 } else {
267 sl->xleft = 0;
268 sl->tx_dropped++;
269 }
270 }
271 sl->xhead = sl->xbuff;
273 if (sl->rcount) {
274 if (sl->rcount <= len) {
275 memcpy(sl->rbuff, rbuff, sl->rcount);
276 } else {
277 sl->rcount = 0;
278 sl->rx_over_errors++;
279 set_bit(SLF_ERROR, &sl->flags);
280 }
281 }
282 sl->mtu = mtu;
283 dev->mtu = mtu;
284 sl->buffsize = len;
285 err = 0;
287 done_on_bh:
288 spin_unlock_bh(&sl->lock);
290 done:
291 kfree(xbuff);
292 kfree(rbuff);
293 #ifdef SL_INCLUDE_CSLIP
294 kfree(cbuff);
295 #endif
296 return err;
297 }
300 /* Set the "sending" flag. This must be atomic hence the set_bit. */
301 static inline void
302 sl_lock(struct slip *sl)
303 {
304 netif_stop_queue(sl->dev);
305 }
308 /* Clear the "sending" flag. This must be atomic, hence the ASM. */
309 static inline void
310 sl_unlock(struct slip *sl)
311 {
312 netif_wake_queue(sl->dev);
313 }
315 /* Send one completely decapsulated IP datagram to the IP layer. */
316 static void
317 sl_bump(struct slip *sl)
318 {
319 struct sk_buff *skb;
320 int count;
322 count = sl->rcount;
323 #ifdef SL_INCLUDE_CSLIP
324 if (sl->mode & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) {
325 unsigned char c;
326 if ((c = sl->rbuff[0]) & SL_TYPE_COMPRESSED_TCP) {
327 /* ignore compressed packets when CSLIP is off */
328 if (!(sl->mode & SL_MODE_CSLIP)) {
329 printk(KERN_WARNING "%s: compressed packet ignored\n", sl->dev->name);
330 return;
331 }
332 /* make sure we've reserved enough space for uncompress to use */
333 if (count + 80 > sl->buffsize) {
334 sl->rx_over_errors++;
335 return;
336 }
337 count = slhc_uncompress(sl->slcomp, sl->rbuff, count);
338 if (count <= 0) {
339 return;
340 }
341 } else if (c >= SL_TYPE_UNCOMPRESSED_TCP) {
342 if (!(sl->mode & SL_MODE_CSLIP)) {
343 /* turn on header compression */
344 sl->mode |= SL_MODE_CSLIP;
345 sl->mode &= ~SL_MODE_ADAPTIVE;
346 printk(KERN_INFO "%s: header compression turned on\n", sl->dev->name);
347 }
348 sl->rbuff[0] &= 0x4f;
349 if (slhc_remember(sl->slcomp, sl->rbuff, count) <= 0) {
350 return;
351 }
352 }
353 }
354 #endif /* SL_INCLUDE_CSLIP */
356 sl->rx_bytes+=count;
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->mac.raw=skb->data;
367 skb->protocol=htons(ETH_P_IP);
368 netif_rx(skb);
369 sl->dev->last_rx = jiffies;
370 sl->rx_packets++;
371 }
373 /* Encapsulate one IP datagram and stuff into a TTY queue. */
374 static void
375 sl_encaps(struct slip *sl, unsigned char *icp, int len)
376 {
377 unsigned char *p;
378 int actual, count;
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->tx_dropped++;
383 sl_unlock(sl);
384 return;
385 }
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 }
392 #endif
393 #ifdef CONFIG_SLIP_MODE_SLIP6
394 if(sl->mode & SL_MODE_SLIP6)
395 count = slip_esc6(p, (unsigned char *) sl->xbuff, len);
396 else
397 #endif
398 count = slip_esc(p, (unsigned char *) sl->xbuff, len);
400 /* Order of next two lines is *very* important.
401 * When we are sending a little amount of data,
402 * the transfer may be completed inside driver.write()
403 * routine, because it's running with interrupts enabled.
404 * In this case we *never* got WRITE_WAKEUP event,
405 * if we did not request it before write operation.
406 * 14 Oct 1994 Dmitry Gorodchanin.
407 */
408 sl->tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
409 actual = sl->tty->driver->write(sl->tty, sl->xbuff, count);
410 #ifdef SL_CHECK_TRANSMIT
411 sl->dev->trans_start = jiffies;
412 #endif
413 sl->xleft = count - actual;
414 sl->xhead = sl->xbuff + actual;
415 #ifdef CONFIG_SLIP_SMART
416 /* VSV */
417 clear_bit(SLF_OUTWAIT, &sl->flags); /* reset outfill flag */
418 #endif
419 }
421 /*
422 * Called by the driver when there's room for more data. If we have
423 * more packets to send, we send them here.
424 */
425 static void slip_write_wakeup(struct tty_struct *tty)
426 {
427 int actual;
428 struct slip *sl = (struct slip *) tty->disc_data;
430 /* First make sure we're connected. */
431 if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev)) {
432 return;
433 }
434 if (sl->xleft <= 0) {
435 /* Now serial buffer is almost free & we can start
436 * transmission of another packet */
437 sl->tx_packets++;
438 tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
439 sl_unlock(sl);
440 return;
441 }
443 actual = tty->driver->write(tty, sl->xhead, sl->xleft);
444 sl->xleft -= actual;
445 sl->xhead += actual;
446 }
448 static void sl_tx_timeout(struct net_device *dev)
449 {
450 struct slip *sl = netdev_priv(dev);
452 spin_lock(&sl->lock);
454 if (netif_queue_stopped(dev)) {
455 if (!netif_running(dev))
456 goto out;
458 /* May be we must check transmitter timeout here ?
459 * 14 Oct 1994 Dmitry Gorodchanin.
460 */
461 #ifdef SL_CHECK_TRANSMIT
462 if (time_before(jiffies, dev->trans_start + 20 * HZ)) {
463 /* 20 sec timeout not reached */
464 goto out;
465 }
466 printk(KERN_WARNING "%s: transmit timed out, %s?\n", dev->name,
467 (sl->tty->driver->chars_in_buffer(sl->tty) || sl->xleft) ?
468 "bad line quality" : "driver error");
469 sl->xleft = 0;
470 sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
471 sl_unlock(sl);
472 #endif
473 }
475 out:
476 spin_unlock(&sl->lock);
477 }
480 /* Encapsulate an IP datagram and kick it into a TTY queue. */
481 static int
482 sl_xmit(struct sk_buff *skb, struct net_device *dev)
483 {
484 struct slip *sl = netdev_priv(dev);
486 spin_lock(&sl->lock);
487 if (!netif_running(dev)) {
488 spin_unlock(&sl->lock);
489 printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name);
490 dev_kfree_skb(skb);
491 return 0;
492 }
493 if (sl->tty == NULL) {
494 spin_unlock(&sl->lock);
495 dev_kfree_skb(skb);
496 return 0;
497 }
499 sl_lock(sl);
500 sl->tx_bytes+=skb->len;
501 sl_encaps(sl, skb->data, skb->len);
502 spin_unlock(&sl->lock);
504 dev_kfree_skb(skb);
505 return 0;
506 }
509 /******************************************
510 * Routines looking at netdevice side.
511 ******************************************/
513 /* Netdevice UP -> DOWN routine */
515 static int
516 sl_close(struct net_device *dev)
517 {
518 struct slip *sl = netdev_priv(dev);
520 spin_lock_bh(&sl->lock);
521 if (sl->tty) {
522 /* TTY discipline is running. */
523 sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
524 }
525 netif_stop_queue(dev);
526 sl->rcount = 0;
527 sl->xleft = 0;
528 spin_unlock_bh(&sl->lock);
530 return 0;
531 }
533 /* Netdevice DOWN -> UP routine */
535 static int sl_open(struct net_device *dev)
536 {
537 struct slip *sl = netdev_priv(dev);
539 if (sl->tty==NULL)
540 return -ENODEV;
542 sl->flags &= (1 << SLF_INUSE);
543 netif_start_queue(dev);
544 return 0;
545 }
547 /* Netdevice change MTU request */
549 static int sl_change_mtu(struct net_device *dev, int new_mtu)
550 {
551 struct slip *sl = netdev_priv(dev);
553 if (new_mtu < 68 || new_mtu > 65534)
554 return -EINVAL;
556 if (new_mtu != dev->mtu)
557 return sl_realloc_bufs(sl, new_mtu);
558 return 0;
559 }
561 /* Netdevice get statistics request */
563 static struct net_device_stats *
564 sl_get_stats(struct net_device *dev)
565 {
566 static struct net_device_stats stats;
567 struct slip *sl = netdev_priv(dev);
568 #ifdef SL_INCLUDE_CSLIP
569 struct slcompress *comp;
570 #endif
572 memset(&stats, 0, sizeof(struct net_device_stats));
574 stats.rx_packets = sl->rx_packets;
575 stats.tx_packets = sl->tx_packets;
576 stats.rx_bytes = sl->rx_bytes;
577 stats.tx_bytes = sl->tx_bytes;
578 stats.rx_dropped = sl->rx_dropped;
579 stats.tx_dropped = sl->tx_dropped;
580 stats.tx_errors = sl->tx_errors;
581 stats.rx_errors = sl->rx_errors;
582 stats.rx_over_errors = sl->rx_over_errors;
583 #ifdef SL_INCLUDE_CSLIP
584 stats.rx_fifo_errors = sl->rx_compressed;
585 stats.tx_fifo_errors = sl->tx_compressed;
586 stats.collisions = sl->tx_misses;
587 comp = sl->slcomp;
588 if (comp) {
589 stats.rx_fifo_errors += comp->sls_i_compressed;
590 stats.rx_dropped += comp->sls_i_tossed;
591 stats.tx_fifo_errors += comp->sls_o_compressed;
592 stats.collisions += comp->sls_o_misses;
593 }
594 #endif /* CONFIG_INET */
595 return (&stats);
596 }
598 /* Netdevice register callback */
600 static int sl_init(struct net_device *dev)
601 {
602 struct slip *sl = netdev_priv(dev);
604 /*
605 * Finish setting up the DEVICE info.
606 */
608 dev->mtu = sl->mtu;
609 dev->type = ARPHRD_SLIP + sl->mode;
610 #ifdef SL_CHECK_TRANSMIT
611 dev->tx_timeout = sl_tx_timeout;
612 dev->watchdog_timeo = 20*HZ;
613 #endif
614 return 0;
615 }
618 static void sl_uninit(struct net_device *dev)
619 {
620 struct slip *sl = netdev_priv(dev);
622 sl_free_bufs(sl);
623 }
625 static void sl_setup(struct net_device *dev)
626 {
627 dev->init = sl_init;
628 dev->uninit = sl_uninit;
629 dev->open = sl_open;
630 dev->destructor = free_netdev;
631 dev->stop = sl_close;
632 dev->get_stats = sl_get_stats;
633 dev->change_mtu = sl_change_mtu;
634 dev->hard_start_xmit = sl_xmit;
635 #ifdef CONFIG_SLIP_SMART
636 dev->do_ioctl = sl_ioctl;
637 #endif
638 dev->hard_header_len = 0;
639 dev->addr_len = 0;
640 dev->tx_queue_len = 10;
642 SET_MODULE_OWNER(dev);
644 /* New-style flags. */
645 dev->flags = IFF_NOARP|IFF_POINTOPOINT|IFF_MULTICAST;
646 }
648 /******************************************
649 Routines looking at TTY side.
650 ******************************************/
653 /*
654 * Handle the 'receiver data ready' interrupt.
655 * This function is called by the 'tty_io' module in the kernel when
656 * a block of SLIP data has been received, which can now be decapsulated
657 * and sent on to some IP layer for further processing. This will not
658 * be re-entered while running but other ldisc functions may be called
659 * in parallel
660 */
662 static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
663 {
664 struct slip *sl = (struct slip *) tty->disc_data;
666 if (!sl || sl->magic != SLIP_MAGIC ||
667 !netif_running(sl->dev))
668 return;
670 /* Read the characters out of the buffer */
671 while (count--) {
672 if (fp && *fp++) {
673 if (!test_and_set_bit(SLF_ERROR, &sl->flags)) {
674 sl->rx_errors++;
675 }
676 cp++;
677 continue;
678 }
679 #ifdef CONFIG_SLIP_MODE_SLIP6
680 if (sl->mode & SL_MODE_SLIP6)
681 slip_unesc6(sl, *cp++);
682 else
683 #endif
684 slip_unesc(sl, *cp++);
685 }
686 }
688 /************************************
689 * slip_open helper routines.
690 ************************************/
692 /* Collect hanged up channels */
694 static void sl_sync(void)
695 {
696 int i;
697 struct net_device *dev;
698 struct slip *sl;
700 for (i = 0; i < slip_maxdev; i++) {
701 if ((dev = slip_devs[i]) == NULL)
702 break;
704 sl = netdev_priv(dev);
705 if (sl->tty || sl->leased)
706 continue;
707 if (dev->flags&IFF_UP)
708 dev_close(dev);
709 }
710 }
713 /* Find a free SLIP channel, and link in this `tty' line. */
714 static struct slip *
715 sl_alloc(dev_t line)
716 {
717 int i;
718 int sel = -1;
719 int score = -1;
720 struct net_device *dev = NULL;
721 struct slip *sl;
723 if (slip_devs == NULL)
724 return NULL; /* Master array missing ! */
726 for (i = 0; i < slip_maxdev; i++) {
727 dev = slip_devs[i];
728 if (dev == NULL)
729 break;
731 sl = netdev_priv(dev);
732 if (sl->leased) {
733 if (sl->line != line)
734 continue;
735 if (sl->tty)
736 return NULL;
738 /* Clear ESCAPE & ERROR flags */
739 sl->flags &= (1 << SLF_INUSE);
740 return sl;
741 }
743 if (sl->tty)
744 continue;
746 if (current->pid == sl->pid) {
747 if (sl->line == line && score < 3) {
748 sel = i;
749 score = 3;
750 continue;
751 }
752 if (score < 2) {
753 sel = i;
754 score = 2;
755 }
756 continue;
757 }
758 if (sl->line == line && score < 1) {
759 sel = i;
760 score = 1;
761 continue;
762 }
763 if (score < 0) {
764 sel = i;
765 score = 0;
766 }
767 }
769 if (sel >= 0) {
770 i = sel;
771 dev = slip_devs[i];
772 if (score > 1) {
773 sl = netdev_priv(dev);
774 sl->flags &= (1 << SLF_INUSE);
775 return sl;
776 }
777 }
779 /* Sorry, too many, all slots in use */
780 if (i >= slip_maxdev)
781 return NULL;
783 if (dev) {
784 sl = netdev_priv(dev);
785 if (test_bit(SLF_INUSE, &sl->flags)) {
786 unregister_netdevice(dev);
787 dev = NULL;
788 slip_devs[i] = NULL;
789 }
790 }
792 if (!dev) {
793 char name[IFNAMSIZ];
794 sprintf(name, "sl%d", i);
796 dev = alloc_netdev(sizeof(*sl), name, sl_setup);
797 if (!dev)
798 return NULL;
799 dev->base_addr = i;
800 }
802 sl = netdev_priv(dev);
804 /* Initialize channel control data */
805 sl->magic = SLIP_MAGIC;
806 sl->dev = dev;
807 spin_lock_init(&sl->lock);
808 sl->mode = SL_MODE_DEFAULT;
809 #ifdef CONFIG_SLIP_SMART
810 init_timer(&sl->keepalive_timer); /* initialize timer_list struct */
811 sl->keepalive_timer.data=(unsigned long)sl;
812 sl->keepalive_timer.function=sl_keepalive;
813 init_timer(&sl->outfill_timer);
814 sl->outfill_timer.data=(unsigned long)sl;
815 sl->outfill_timer.function=sl_outfill;
816 #endif
817 slip_devs[i] = dev;
819 return sl;
820 }
822 /*
823 * Open the high-level part of the SLIP channel.
824 * This function is called by the TTY module when the
825 * SLIP line discipline is called for. Because we are
826 * sure the tty line exists, we only have to link it to
827 * a free SLIP channel...
828 *
829 * Called in process context serialized from other ldisc calls.
830 */
832 static int slip_open(struct tty_struct *tty)
833 {
834 struct slip *sl;
835 int err;
837 if(!capable(CAP_NET_ADMIN))
838 return -EPERM;
840 /* RTnetlink lock is misused here to serialize concurrent
841 opens of slip channels. There are better ways, but it is
842 the simplest one.
843 */
844 rtnl_lock();
846 /* Collect hanged up channels. */
847 sl_sync();
849 sl = (struct slip *) tty->disc_data;
851 err = -EEXIST;
852 /* First make sure we're not already connected. */
853 if (sl && sl->magic == SLIP_MAGIC)
854 goto err_exit;
856 /* OK. Find a free SLIP channel to use. */
857 err = -ENFILE;
858 if ((sl = sl_alloc(tty_devnum(tty))) == NULL)
859 goto err_exit;
861 sl->tty = tty;
862 tty->disc_data = sl;
863 sl->line = tty_devnum(tty);
864 sl->pid = current->pid;
866 if (!test_bit(SLF_INUSE, &sl->flags)) {
867 /* Perform the low-level SLIP initialization. */
868 if ((err = sl_alloc_bufs(sl, SL_MTU)) != 0)
869 goto err_free_chan;
871 set_bit(SLF_INUSE, &sl->flags);
873 if ((err = register_netdevice(sl->dev)))
874 goto err_free_bufs;
875 }
877 #ifdef CONFIG_SLIP_SMART
878 if (sl->keepalive) {
879 sl->keepalive_timer.expires=jiffies+sl->keepalive*HZ;
880 add_timer (&sl->keepalive_timer);
881 }
882 if (sl->outfill) {
883 sl->outfill_timer.expires=jiffies+sl->outfill*HZ;
884 add_timer (&sl->outfill_timer);
885 }
886 #endif
888 /* Done. We have linked the TTY line to a channel. */
889 rtnl_unlock();
890 tty->receive_room = 65536; /* We don't flow control */
891 return sl->dev->base_addr;
893 err_free_bufs:
894 sl_free_bufs(sl);
896 err_free_chan:
897 sl->tty = NULL;
898 tty->disc_data = NULL;
899 clear_bit(SLF_INUSE, &sl->flags);
901 err_exit:
902 rtnl_unlock();
904 /* Count references from TTY module */
905 return err;
906 }
908 /*
910 FIXME: 1,2 are fixed 3 was never true anyway.
912 Let me to blame a bit.
913 1. TTY module calls this funstion on soft interrupt.
914 2. TTY module calls this function WITH MASKED INTERRUPTS!
915 3. TTY module does not notify us about line discipline
916 shutdown,
918 Seems, now it is clean. The solution is to consider netdevice and
919 line discipline sides as two independent threads.
921 By-product (not desired): sl? does not feel hangups and remains open.
922 It is supposed, that user level program (dip, diald, slattach...)
923 will catch SIGHUP and make the rest of work.
925 I see no way to make more with current tty code. --ANK
926 */
928 /*
929 * Close down a SLIP channel.
930 * This means flushing out any pending queues, and then returning. This
931 * call is serialized against other ldisc functions.
932 */
933 static void
934 slip_close(struct tty_struct *tty)
935 {
936 struct slip *sl = (struct slip *) tty->disc_data;
938 /* First make sure we're connected. */
939 if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty)
940 return;
942 tty->disc_data = NULL;
943 sl->tty = NULL;
944 if (!sl->leased)
945 sl->line = 0;
947 /* VSV = very important to remove timers */
948 #ifdef CONFIG_SLIP_SMART
949 del_timer_sync(&sl->keepalive_timer);
950 del_timer_sync(&sl->outfill_timer);
951 #endif
953 /* Count references from TTY module */
954 }
956 /************************************************************************
957 * STANDARD SLIP ENCAPSULATION *
958 ************************************************************************/
960 int
961 slip_esc(unsigned char *s, unsigned char *d, int len)
962 {
963 unsigned char *ptr = d;
964 unsigned char c;
966 /*
967 * Send an initial END character to flush out any
968 * data that may have accumulated in the receiver
969 * due to line noise.
970 */
972 *ptr++ = END;
974 /*
975 * For each byte in the packet, send the appropriate
976 * character sequence, according to the SLIP protocol.
977 */
979 while (len-- > 0) {
980 switch(c = *s++) {
981 case END:
982 *ptr++ = ESC;
983 *ptr++ = ESC_END;
984 break;
985 case ESC:
986 *ptr++ = ESC;
987 *ptr++ = ESC_ESC;
988 break;
989 default:
990 *ptr++ = c;
991 break;
992 }
993 }
994 *ptr++ = END;
995 return (ptr - d);
996 }
998 static void slip_unesc(struct slip *sl, unsigned char s)
999 {
1001 switch(s) {
1002 case END:
1003 #ifdef CONFIG_SLIP_SMART
1004 /* drop keeptest bit = VSV */
1005 if (test_bit(SLF_KEEPTEST, &sl->flags))
1006 clear_bit(SLF_KEEPTEST, &sl->flags);
1007 #endif
1009 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) && (sl->rcount > 2)) {
1010 sl_bump(sl);
1012 clear_bit(SLF_ESCAPE, &sl->flags);
1013 sl->rcount = 0;
1014 return;
1016 case ESC:
1017 set_bit(SLF_ESCAPE, &sl->flags);
1018 return;
1019 case ESC_ESC:
1020 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags)) {
1021 s = ESC;
1023 break;
1024 case ESC_END:
1025 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags)) {
1026 s = END;
1028 break;
1030 if (!test_bit(SLF_ERROR, &sl->flags)) {
1031 if (sl->rcount < sl->buffsize) {
1032 sl->rbuff[sl->rcount++] = s;
1033 return;
1035 sl->rx_over_errors++;
1036 set_bit(SLF_ERROR, &sl->flags);
1041 #ifdef CONFIG_SLIP_MODE_SLIP6
1042 /************************************************************************
1043 * 6 BIT SLIP ENCAPSULATION *
1044 ************************************************************************/
1046 int
1047 slip_esc6(unsigned char *s, unsigned char *d, int len)
1049 unsigned char *ptr = d;
1050 unsigned char c;
1051 int i;
1052 unsigned short v = 0;
1053 short bits = 0;
1055 /*
1056 * Send an initial END character to flush out any
1057 * data that may have accumulated in the receiver
1058 * due to line noise.
1059 */
1061 *ptr++ = 0x70;
1063 /*
1064 * Encode the packet into printable ascii characters
1065 */
1067 for (i = 0; i < len; ++i) {
1068 v = (v << 8) | s[i];
1069 bits += 8;
1070 while (bits >= 6) {
1071 bits -= 6;
1072 c = 0x30 + ((v >> bits) & 0x3F);
1073 *ptr++ = c;
1076 if (bits) {
1077 c = 0x30 + ((v << (6 - bits)) & 0x3F);
1078 *ptr++ = c;
1080 *ptr++ = 0x70;
1081 return ptr - d;
1084 void
1085 slip_unesc6(struct slip *sl, unsigned char s)
1087 unsigned char c;
1089 if (s == 0x70) {
1090 #ifdef CONFIG_SLIP_SMART
1091 /* drop keeptest bit = VSV */
1092 if (test_bit(SLF_KEEPTEST, &sl->flags))
1093 clear_bit(SLF_KEEPTEST, &sl->flags);
1094 #endif
1096 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) && (sl->rcount > 2)) {
1097 sl_bump(sl);
1099 sl->rcount = 0;
1100 sl->xbits = 0;
1101 sl->xdata = 0;
1102 } else if (s >= 0x30 && s < 0x70) {
1103 sl->xdata = (sl->xdata << 6) | ((s - 0x30) & 0x3F);
1104 sl->xbits += 6;
1105 if (sl->xbits >= 8) {
1106 sl->xbits -= 8;
1107 c = (unsigned char)(sl->xdata >> sl->xbits);
1108 if (!test_bit(SLF_ERROR, &sl->flags)) {
1109 if (sl->rcount < sl->buffsize) {
1110 sl->rbuff[sl->rcount++] = c;
1111 return;
1113 sl->rx_over_errors++;
1114 set_bit(SLF_ERROR, &sl->flags);
1119 #endif /* CONFIG_SLIP_MODE_SLIP6 */
1121 /* Perform I/O control on an active SLIP channel. */
1122 static int slip_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg)
1124 struct slip *sl = (struct slip *) tty->disc_data;
1125 unsigned int tmp;
1126 int __user *p = (int __user *)arg;
1128 /* First make sure we're connected. */
1129 if (!sl || sl->magic != SLIP_MAGIC) {
1130 return -EINVAL;
1133 switch(cmd) {
1134 case SIOCGIFNAME:
1135 tmp = strlen(sl->dev->name) + 1;
1136 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
1137 return -EFAULT;
1138 return 0;
1140 case SIOCGIFENCAP:
1141 if (put_user(sl->mode, p))
1142 return -EFAULT;
1143 return 0;
1145 case SIOCSIFENCAP:
1146 if (get_user(tmp, p))
1147 return -EFAULT;
1148 #ifndef SL_INCLUDE_CSLIP
1149 if (tmp & (SL_MODE_CSLIP|SL_MODE_ADAPTIVE)) {
1150 return -EINVAL;
1152 #else
1153 if ((tmp & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) ==
1154 (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) {
1155 /* return -EINVAL; */
1156 tmp &= ~SL_MODE_ADAPTIVE;
1158 #endif
1159 #ifndef CONFIG_SLIP_MODE_SLIP6
1160 if (tmp & SL_MODE_SLIP6) {
1161 return -EINVAL;
1163 #endif
1164 sl->mode = tmp;
1165 sl->dev->type = ARPHRD_SLIP+sl->mode;
1166 return 0;
1168 case SIOCSIFHWADDR:
1169 return -EINVAL;
1171 #ifdef CONFIG_SLIP_SMART
1172 /* VSV changes start here */
1173 case SIOCSKEEPALIVE:
1174 if (get_user(tmp, p))
1175 return -EFAULT;
1176 if (tmp > 255) /* max for unchar */
1177 return -EINVAL;
1179 spin_lock_bh(&sl->lock);
1180 if (!sl->tty) {
1181 spin_unlock_bh(&sl->lock);
1182 return -ENODEV;
1184 if ((sl->keepalive = (unchar) tmp) != 0) {
1185 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
1186 set_bit(SLF_KEEPTEST, &sl->flags);
1187 } else {
1188 del_timer (&sl->keepalive_timer);
1190 spin_unlock_bh(&sl->lock);
1191 return 0;
1193 case SIOCGKEEPALIVE:
1194 if (put_user(sl->keepalive, p))
1195 return -EFAULT;
1196 return 0;
1198 case SIOCSOUTFILL:
1199 if (get_user(tmp, p))
1200 return -EFAULT;
1201 if (tmp > 255) /* max for unchar */
1202 return -EINVAL;
1203 spin_lock_bh(&sl->lock);
1204 if (!sl->tty) {
1205 spin_unlock_bh(&sl->lock);
1206 return -ENODEV;
1208 if ((sl->outfill = (unchar) tmp) != 0){
1209 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
1210 set_bit(SLF_OUTWAIT, &sl->flags);
1211 } else {
1212 del_timer (&sl->outfill_timer);
1214 spin_unlock_bh(&sl->lock);
1215 return 0;
1217 case SIOCGOUTFILL:
1218 if (put_user(sl->outfill, p))
1219 return -EFAULT;
1220 return 0;
1221 /* VSV changes end */
1222 #endif
1224 /* Allow stty to read, but not set, the serial port */
1225 case TCGETS:
1226 case TCGETA:
1227 return n_tty_ioctl(tty, file, cmd, arg);
1229 default:
1230 return -ENOIOCTLCMD;
1234 /* VSV changes start here */
1235 #ifdef CONFIG_SLIP_SMART
1236 /* function do_ioctl called from net/core/dev.c
1237 to allow get/set outfill/keepalive parameter
1238 by ifconfig */
1240 static int sl_ioctl(struct net_device *dev,struct ifreq *rq,int cmd)
1242 struct slip *sl = netdev_priv(dev);
1243 unsigned long *p = (unsigned long *)&rq->ifr_ifru;
1245 if (sl == NULL) /* Allocation failed ?? */
1246 return -ENODEV;
1248 spin_lock_bh(&sl->lock);
1250 if (!sl->tty) {
1251 spin_unlock_bh(&sl->lock);
1252 return -ENODEV;
1255 switch(cmd){
1256 case SIOCSKEEPALIVE:
1257 /* max for unchar */
1258 if ((unsigned)*p > 255) {
1259 spin_unlock_bh(&sl->lock);
1260 return -EINVAL;
1262 sl->keepalive = (unchar) *p;
1263 if (sl->keepalive != 0) {
1264 sl->keepalive_timer.expires=jiffies+sl->keepalive*HZ;
1265 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
1266 set_bit(SLF_KEEPTEST, &sl->flags);
1267 } else {
1268 del_timer(&sl->keepalive_timer);
1270 break;
1272 case SIOCGKEEPALIVE:
1273 *p = sl->keepalive;
1274 break;
1276 case SIOCSOUTFILL:
1277 if ((unsigned)*p > 255) { /* max for unchar */
1278 spin_unlock_bh(&sl->lock);
1279 return -EINVAL;
1281 if ((sl->outfill = (unchar)*p) != 0){
1282 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
1283 set_bit(SLF_OUTWAIT, &sl->flags);
1284 } else {
1285 del_timer (&sl->outfill_timer);
1287 break;
1289 case SIOCGOUTFILL:
1290 *p = sl->outfill;
1291 break;
1293 case SIOCSLEASE:
1294 /* Resolve race condition, when ioctl'ing hanged up
1295 and opened by another process device.
1296 */
1297 if (sl->tty != current->signal->tty && sl->pid != current->pid) {
1298 spin_unlock_bh(&sl->lock);
1299 return -EPERM;
1301 sl->leased = 0;
1302 if (*p)
1303 sl->leased = 1;
1304 break;
1306 case SIOCGLEASE:
1307 *p = sl->leased;
1308 };
1309 spin_unlock_bh(&sl->lock);
1310 return 0;
1312 #endif
1313 /* VSV changes end */
1315 static struct tty_ldisc sl_ldisc = {
1316 .owner = THIS_MODULE,
1317 .magic = TTY_LDISC_MAGIC,
1318 .name = "slip",
1319 .open = slip_open,
1320 .close = slip_close,
1321 .ioctl = slip_ioctl,
1322 .receive_buf = slip_receive_buf,
1323 .write_wakeup = slip_write_wakeup,
1324 };
1326 static int __init slip_init(void)
1328 int status;
1330 if (slip_maxdev < 4)
1331 slip_maxdev = 4; /* Sanity */
1333 printk(KERN_INFO "SLIP: version %s (dynamic channels, max=%d)"
1334 #ifdef CONFIG_SLIP_MODE_SLIP6
1335 " (6 bit encapsulation enabled)"
1336 #endif
1337 ".\n",
1338 SLIP_VERSION, slip_maxdev );
1339 #if defined(SL_INCLUDE_CSLIP)
1340 printk(KERN_INFO "CSLIP: code copyright 1989 Regents of the University of California.\n");
1341 #endif
1342 #ifdef CONFIG_SLIP_SMART
1343 printk(KERN_INFO "SLIP linefill/keepalive option.\n");
1344 #endif
1346 slip_devs = kmalloc(sizeof(struct net_device *)*slip_maxdev, GFP_KERNEL);
1347 if (!slip_devs) {
1348 printk(KERN_ERR "SLIP: Can't allocate slip devices array! Uaargh! (-> No SLIP available)\n");
1349 return -ENOMEM;
1352 /* Clear the pointer array, we allocate devices when we need them */
1353 memset(slip_devs, 0, sizeof(struct net_device *)*slip_maxdev);
1355 /* Fill in our line protocol discipline, and register it */
1356 if ((status = tty_register_ldisc(N_SLIP, &sl_ldisc)) != 0) {
1357 printk(KERN_ERR "SLIP: can't register line discipline (err = %d)\n", status);
1358 kfree(slip_devs);
1360 return status;
1363 static void __exit slip_exit(void)
1365 int i;
1366 struct net_device *dev;
1367 struct slip *sl;
1368 unsigned long timeout = jiffies + HZ;
1369 int busy = 0;
1371 if (slip_devs == NULL)
1372 return;
1374 /* First of all: check for active disciplines and hangup them.
1375 */
1376 do {
1377 if (busy)
1378 msleep_interruptible(100);
1380 busy = 0;
1381 for (i = 0; i < slip_maxdev; i++) {
1382 dev = slip_devs[i];
1383 if (!dev)
1384 continue;
1385 sl = netdev_priv(dev);
1386 spin_lock_bh(&sl->lock);
1387 if (sl->tty) {
1388 busy++;
1389 tty_hangup(sl->tty);
1391 spin_unlock_bh(&sl->lock);
1393 } while (busy && time_before(jiffies, timeout));
1396 for (i = 0; i < slip_maxdev; i++) {
1397 dev = slip_devs[i];
1398 if (!dev)
1399 continue;
1400 slip_devs[i] = NULL;
1402 sl = netdev_priv(dev);
1403 if (sl->tty) {
1404 printk(KERN_ERR "%s: tty discipline still running\n",
1405 dev->name);
1406 /* Intentionally leak the control block. */
1407 dev->destructor = NULL;
1410 unregister_netdev(dev);
1413 kfree(slip_devs);
1414 slip_devs = NULL;
1416 if ((i = tty_unregister_ldisc(N_SLIP)))
1418 printk(KERN_ERR "SLIP: can't unregister line discipline (err = %d)\n", i);
1422 module_init(slip_init);
1423 module_exit(slip_exit);
1425 #ifdef CONFIG_SLIP_SMART
1426 /*
1427 * This is start of the code for multislip style line checking
1428 * added by Stanislav Voronyi. All changes before marked VSV
1429 */
1431 static void sl_outfill(unsigned long sls)
1433 struct slip *sl=(struct slip *)sls;
1435 spin_lock(&sl->lock);
1437 if (sl->tty == NULL)
1438 goto out;
1440 if(sl->outfill)
1442 if( test_bit(SLF_OUTWAIT, &sl->flags) )
1444 /* no packets were transmitted, do outfill */
1445 #ifdef CONFIG_SLIP_MODE_SLIP6
1446 unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END;
1447 #else
1448 unsigned char s = END;
1449 #endif
1450 /* put END into tty queue. Is it right ??? */
1451 if (!netif_queue_stopped(sl->dev))
1453 /* if device busy no outfill */
1454 sl->tty->driver->write(sl->tty, &s, 1);
1457 else
1458 set_bit(SLF_OUTWAIT, &sl->flags);
1460 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
1462 out:
1463 spin_unlock(&sl->lock);
1466 static void sl_keepalive(unsigned long sls)
1468 struct slip *sl=(struct slip *)sls;
1470 spin_lock(&sl->lock);
1472 if (sl->tty == NULL)
1473 goto out;
1475 if( sl->keepalive)
1477 if(test_bit(SLF_KEEPTEST, &sl->flags))
1479 /* keepalive still high :(, we must hangup */
1480 if( sl->outfill ) /* outfill timer must be deleted too */
1481 (void)del_timer(&sl->outfill_timer);
1482 printk(KERN_DEBUG "%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name);
1483 tty_hangup(sl->tty); /* this must hangup tty & close slip */
1484 /* I think we need not something else */
1485 goto out;
1487 else
1488 set_bit(SLF_KEEPTEST, &sl->flags);
1490 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
1493 out:
1494 spin_unlock(&sl->lock);
1497 #endif
1498 MODULE_LICENSE("GPL");
1499 MODULE_ALIAS_LDISC(N_SLIP);