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Oliver Hartkoppa1044e32010-12-02 10:57:59 +00001/*
2 * slcan.c - serial line CAN interface driver (using tty line discipline)
3 *
4 * This file is derived from linux/drivers/net/slip.c
5 *
6 * slip.c Authors : Laurence Culhane <loz@holmes.demon.co.uk>
7 * Fred N. van Kempen <waltje@uwalt.nl.mugnet.org>
8 * slcan.c Author : Oliver Hartkopp <socketcan@hartkopp.net>
9 *
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by the
12 * Free Software Foundation; either version 2 of the License, or (at your
13 * option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License along
21 * with this program; if not, write to the Free Software Foundation, Inc.,
22 * 59 Temple Place, Suite 330, Boston, MA 02111-1307. You can also get it
23 * at http://www.gnu.org/licenses/gpl.html
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
27 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
28 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
29 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
30 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
31 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
35 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
36 * DAMAGE.
37 *
38 * Send feedback to <socketcan-users@lists.berlios.de>
39 *
40 */
41
42#include <linux/module.h>
43#include <linux/moduleparam.h>
44
45#include <asm/system.h>
46#include <linux/uaccess.h>
47#include <linux/bitops.h>
48#include <linux/string.h>
49#include <linux/tty.h>
50#include <linux/errno.h>
51#include <linux/netdevice.h>
52#include <linux/skbuff.h>
53#include <linux/rtnetlink.h>
54#include <linux/if_arp.h>
55#include <linux/if_ether.h>
David S. Miller84b3cdc2010-12-08 18:41:03 -080056#include <linux/sched.h>
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000057#include <linux/delay.h>
58#include <linux/init.h>
59#include <linux/can.h>
60
61static __initdata const char banner[] =
62 KERN_INFO "slcan: serial line CAN interface driver\n";
63
64MODULE_ALIAS_LDISC(N_SLCAN);
65MODULE_DESCRIPTION("serial line CAN interface");
66MODULE_LICENSE("GPL");
67MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
68
69#define SLCAN_MAGIC 0x53CA
70
71static int maxdev = 10; /* MAX number of SLCAN channels;
72 This can be overridden with
73 insmod slcan.ko maxdev=nnn */
74module_param(maxdev, int, 0);
75MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
76
77/* maximum rx buffer len: extended CAN frame with timestamp */
78#define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
79
80struct slcan {
81 int magic;
82
83 /* Various fields. */
84 struct tty_struct *tty; /* ptr to TTY structure */
85 struct net_device *dev; /* easy for intr handling */
86 spinlock_t lock;
87
88 /* These are pointers to the malloc()ed frame buffers. */
89 unsigned char rbuff[SLC_MTU]; /* receiver buffer */
90 int rcount; /* received chars counter */
91 unsigned char xbuff[SLC_MTU]; /* transmitter buffer */
92 unsigned char *xhead; /* pointer to next XMIT byte */
93 int xleft; /* bytes left in XMIT queue */
94
95 unsigned long flags; /* Flag values/ mode etc */
96#define SLF_INUSE 0 /* Channel in use */
97#define SLF_ERROR 1 /* Parity, etc. error */
98
99 unsigned char leased;
100 dev_t line;
101 pid_t pid;
102};
103
104static struct net_device **slcan_devs;
105
106 /************************************************************************
107 * SLCAN ENCAPSULATION FORMAT *
108 ************************************************************************/
109
110/*
111 * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
112 * frame format) a data length code (can_dlc) which can be from 0 to 8
113 * and up to <can_dlc> data bytes as payload.
114 * Additionally a CAN frame may become a remote transmission frame if the
115 * RTR-bit is set. This causes another ECU to send a CAN frame with the
116 * given can_id.
117 *
118 * The SLCAN ASCII representation of these different frame types is:
119 * <type> <id> <dlc> <data>*
120 *
121 * Extended frames (29 bit) are defined by capital characters in the type.
122 * RTR frames are defined as 'r' types - normal frames have 't' type:
123 * t => 11 bit data frame
124 * r => 11 bit RTR frame
125 * T => 29 bit data frame
126 * R => 29 bit RTR frame
127 *
128 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
129 * The <dlc> is a one byte ASCII number ('0' - '8')
130 * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
131 *
132 * Examples:
133 *
134 * t1230 : can_id 0x123, can_dlc 0, no data
135 * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
136 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
137 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
138 *
139 */
140
141 /************************************************************************
142 * STANDARD SLCAN DECAPSULATION *
143 ************************************************************************/
144
145static int asc2nibble(char c)
146{
147
148 if ((c >= '0') && (c <= '9'))
149 return c - '0';
150
151 if ((c >= 'A') && (c <= 'F'))
152 return c - 'A' + 10;
153
154 if ((c >= 'a') && (c <= 'f'))
155 return c - 'a' + 10;
156
157 return 16; /* error */
158}
159
160/* Send one completely decapsulated can_frame to the network layer */
161static void slc_bump(struct slcan *sl)
162{
163 struct sk_buff *skb;
164 struct can_frame cf;
165 int i, dlc_pos, tmp;
166 unsigned long ultmp;
167 char cmd = sl->rbuff[0];
168
169 if ((cmd != 't') && (cmd != 'T') && (cmd != 'r') && (cmd != 'R'))
170 return;
171
172 if (cmd & 0x20) /* tiny chars 'r' 't' => standard frame format */
173 dlc_pos = 4; /* dlc position tiiid */
174 else
175 dlc_pos = 9; /* dlc position Tiiiiiiiid */
176
177 if (!((sl->rbuff[dlc_pos] >= '0') && (sl->rbuff[dlc_pos] < '9')))
178 return;
179
180 cf.can_dlc = sl->rbuff[dlc_pos] - '0'; /* get can_dlc from ASCII val */
181
182 sl->rbuff[dlc_pos] = 0; /* terminate can_id string */
183
184 if (strict_strtoul(sl->rbuff+1, 16, &ultmp))
185 return;
186
187 cf.can_id = ultmp;
188
189 if (!(cmd & 0x20)) /* NO tiny chars => extended frame format */
190 cf.can_id |= CAN_EFF_FLAG;
191
192 if ((cmd | 0x20) == 'r') /* RTR frame */
193 cf.can_id |= CAN_RTR_FLAG;
194
195 *(u64 *) (&cf.data) = 0; /* clear payload */
196
197 for (i = 0, dlc_pos++; i < cf.can_dlc; i++) {
198
199 tmp = asc2nibble(sl->rbuff[dlc_pos++]);
200 if (tmp > 0x0F)
201 return;
202 cf.data[i] = (tmp << 4);
203 tmp = asc2nibble(sl->rbuff[dlc_pos++]);
204 if (tmp > 0x0F)
205 return;
206 cf.data[i] |= tmp;
207 }
208
209
210 skb = dev_alloc_skb(sizeof(struct can_frame));
211 if (!skb)
212 return;
213
214 skb->dev = sl->dev;
215 skb->protocol = htons(ETH_P_CAN);
216 skb->pkt_type = PACKET_BROADCAST;
217 skb->ip_summed = CHECKSUM_UNNECESSARY;
218 memcpy(skb_put(skb, sizeof(struct can_frame)),
219 &cf, sizeof(struct can_frame));
220 netif_rx(skb);
221
222 sl->dev->stats.rx_packets++;
223 sl->dev->stats.rx_bytes += cf.can_dlc;
224}
225
226/* parse tty input stream */
227static void slcan_unesc(struct slcan *sl, unsigned char s)
228{
229
230 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
231 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
232 (sl->rcount > 4)) {
233 slc_bump(sl);
234 }
235 sl->rcount = 0;
236 } else {
237 if (!test_bit(SLF_ERROR, &sl->flags)) {
238 if (sl->rcount < SLC_MTU) {
239 sl->rbuff[sl->rcount++] = s;
240 return;
241 } else {
242 sl->dev->stats.rx_over_errors++;
243 set_bit(SLF_ERROR, &sl->flags);
244 }
245 }
246 }
247}
248
249 /************************************************************************
250 * STANDARD SLCAN ENCAPSULATION *
251 ************************************************************************/
252
253/* Encapsulate one can_frame and stuff into a TTY queue. */
254static void slc_encaps(struct slcan *sl, struct can_frame *cf)
255{
256 int actual, idx, i;
257 char cmd;
258
259 if (cf->can_id & CAN_RTR_FLAG)
260 cmd = 'R'; /* becomes 'r' in standard frame format */
261 else
262 cmd = 'T'; /* becomes 't' in standard frame format */
263
264 if (cf->can_id & CAN_EFF_FLAG)
265 sprintf(sl->xbuff, "%c%08X%d", cmd,
266 cf->can_id & CAN_EFF_MASK, cf->can_dlc);
267 else
268 sprintf(sl->xbuff, "%c%03X%d", cmd | 0x20,
269 cf->can_id & CAN_SFF_MASK, cf->can_dlc);
270
271 idx = strlen(sl->xbuff);
272
273 for (i = 0; i < cf->can_dlc; i++)
274 sprintf(&sl->xbuff[idx + 2*i], "%02X", cf->data[i]);
275
276 strcat(sl->xbuff, "\r"); /* add terminating character */
277
278 /* Order of next two lines is *very* important.
279 * When we are sending a little amount of data,
280 * the transfer may be completed inside the ops->write()
281 * routine, because it's running with interrupts enabled.
282 * In this case we *never* got WRITE_WAKEUP event,
283 * if we did not request it before write operation.
284 * 14 Oct 1994 Dmitry Gorodchanin.
285 */
286 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
287 actual = sl->tty->ops->write(sl->tty, sl->xbuff, strlen(sl->xbuff));
288 sl->xleft = strlen(sl->xbuff) - actual;
289 sl->xhead = sl->xbuff + actual;
290 sl->dev->stats.tx_bytes += cf->can_dlc;
291}
292
293/*
294 * Called by the driver when there's room for more data. If we have
295 * more packets to send, we send them here.
296 */
297static void slcan_write_wakeup(struct tty_struct *tty)
298{
299 int actual;
300 struct slcan *sl = (struct slcan *) tty->disc_data;
301
302 /* First make sure we're connected. */
303 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
304 return;
305
306 if (sl->xleft <= 0) {
307 /* Now serial buffer is almost free & we can start
308 * transmission of another packet */
309 sl->dev->stats.tx_packets++;
310 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
311 netif_wake_queue(sl->dev);
312 return;
313 }
314
315 actual = tty->ops->write(tty, sl->xhead, sl->xleft);
316 sl->xleft -= actual;
317 sl->xhead += actual;
318}
319
320/* Send a can_frame to a TTY queue. */
321static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
322{
323 struct slcan *sl = netdev_priv(dev);
324
325 if (skb->len != sizeof(struct can_frame))
326 goto out;
327
328 spin_lock(&sl->lock);
329 if (!netif_running(dev)) {
330 spin_unlock(&sl->lock);
331 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
332 goto out;
333 }
334 if (sl->tty == NULL) {
335 spin_unlock(&sl->lock);
336 goto out;
337 }
338
339 netif_stop_queue(sl->dev);
340 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
341 spin_unlock(&sl->lock);
342
343out:
344 kfree_skb(skb);
345 return NETDEV_TX_OK;
346}
347
348
349/******************************************
350 * Routines looking at netdevice side.
351 ******************************************/
352
353/* Netdevice UP -> DOWN routine */
354static int slc_close(struct net_device *dev)
355{
356 struct slcan *sl = netdev_priv(dev);
357
358 spin_lock_bh(&sl->lock);
359 if (sl->tty) {
360 /* TTY discipline is running. */
361 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
362 }
363 netif_stop_queue(dev);
364 sl->rcount = 0;
365 sl->xleft = 0;
366 spin_unlock_bh(&sl->lock);
367
368 return 0;
369}
370
371/* Netdevice DOWN -> UP routine */
372static int slc_open(struct net_device *dev)
373{
374 struct slcan *sl = netdev_priv(dev);
375
376 if (sl->tty == NULL)
377 return -ENODEV;
378
379 sl->flags &= (1 << SLF_INUSE);
380 netif_start_queue(dev);
381 return 0;
382}
383
384/* Hook the destructor so we can free slcan devs at the right point in time */
385static void slc_free_netdev(struct net_device *dev)
386{
387 int i = dev->base_addr;
388 free_netdev(dev);
389 slcan_devs[i] = NULL;
390}
391
392static const struct net_device_ops slc_netdev_ops = {
393 .ndo_open = slc_open,
394 .ndo_stop = slc_close,
395 .ndo_start_xmit = slc_xmit,
396};
397
398static void slc_setup(struct net_device *dev)
399{
400 dev->netdev_ops = &slc_netdev_ops;
401 dev->destructor = slc_free_netdev;
402
403 dev->hard_header_len = 0;
404 dev->addr_len = 0;
405 dev->tx_queue_len = 10;
406
407 dev->mtu = sizeof(struct can_frame);
408 dev->type = ARPHRD_CAN;
409
410 /* New-style flags. */
411 dev->flags = IFF_NOARP;
412 dev->features = NETIF_F_NO_CSUM;
413}
414
415/******************************************
416 Routines looking at TTY side.
417 ******************************************/
418
419/*
420 * Handle the 'receiver data ready' interrupt.
421 * This function is called by the 'tty_io' module in the kernel when
422 * a block of SLCAN data has been received, which can now be decapsulated
423 * and sent on to some IP layer for further processing. This will not
424 * be re-entered while running but other ldisc functions may be called
425 * in parallel
426 */
427
Linus Torvalds55db4c62011-06-04 06:33:24 +0900428static void slcan_receive_buf(struct tty_struct *tty,
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000429 const unsigned char *cp, char *fp, int count)
430{
431 struct slcan *sl = (struct slcan *) tty->disc_data;
432
433 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
Linus Torvalds55db4c62011-06-04 06:33:24 +0900434 return;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000435
436 /* Read the characters out of the buffer */
Linus Torvalds55db4c62011-06-04 06:33:24 +0900437 while (count--) {
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000438 if (fp && *fp++) {
439 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
440 sl->dev->stats.rx_errors++;
441 cp++;
442 continue;
443 }
444 slcan_unesc(sl, *cp++);
445 }
446}
447
448/************************************
449 * slcan_open helper routines.
450 ************************************/
451
452/* Collect hanged up channels */
453static void slc_sync(void)
454{
455 int i;
456 struct net_device *dev;
457 struct slcan *sl;
458
459 for (i = 0; i < maxdev; i++) {
460 dev = slcan_devs[i];
461 if (dev == NULL)
462 break;
463
464 sl = netdev_priv(dev);
465 if (sl->tty || sl->leased)
466 continue;
467 if (dev->flags & IFF_UP)
468 dev_close(dev);
469 }
470}
471
472/* Find a free SLCAN channel, and link in this `tty' line. */
473static struct slcan *slc_alloc(dev_t line)
474{
475 int i;
476 struct net_device *dev = NULL;
477 struct slcan *sl;
478
479 if (slcan_devs == NULL)
480 return NULL; /* Master array missing ! */
481
482 for (i = 0; i < maxdev; i++) {
483 dev = slcan_devs[i];
484 if (dev == NULL)
485 break;
486
487 }
488
489 /* Sorry, too many, all slots in use */
490 if (i >= maxdev)
491 return NULL;
492
493 if (dev) {
494 sl = netdev_priv(dev);
495 if (test_bit(SLF_INUSE, &sl->flags)) {
496 unregister_netdevice(dev);
497 dev = NULL;
498 slcan_devs[i] = NULL;
499 }
500 }
501
502 if (!dev) {
503 char name[IFNAMSIZ];
504 sprintf(name, "slcan%d", i);
505
506 dev = alloc_netdev(sizeof(*sl), name, slc_setup);
507 if (!dev)
508 return NULL;
509 dev->base_addr = i;
510 }
511
512 sl = netdev_priv(dev);
513
514 /* Initialize channel control data */
515 sl->magic = SLCAN_MAGIC;
516 sl->dev = dev;
517 spin_lock_init(&sl->lock);
518 slcan_devs[i] = dev;
519
520 return sl;
521}
522
523/*
524 * Open the high-level part of the SLCAN channel.
525 * This function is called by the TTY module when the
526 * SLCAN line discipline is called for. Because we are
527 * sure the tty line exists, we only have to link it to
528 * a free SLCAN channel...
529 *
530 * Called in process context serialized from other ldisc calls.
531 */
532
533static int slcan_open(struct tty_struct *tty)
534{
535 struct slcan *sl;
536 int err;
537
538 if (!capable(CAP_NET_ADMIN))
539 return -EPERM;
540
541 if (tty->ops->write == NULL)
542 return -EOPNOTSUPP;
543
544 /* RTnetlink lock is misused here to serialize concurrent
545 opens of slcan channels. There are better ways, but it is
546 the simplest one.
547 */
548 rtnl_lock();
549
550 /* Collect hanged up channels. */
551 slc_sync();
552
553 sl = tty->disc_data;
554
555 err = -EEXIST;
556 /* First make sure we're not already connected. */
557 if (sl && sl->magic == SLCAN_MAGIC)
558 goto err_exit;
559
560 /* OK. Find a free SLCAN channel to use. */
561 err = -ENFILE;
562 sl = slc_alloc(tty_devnum(tty));
563 if (sl == NULL)
564 goto err_exit;
565
566 sl->tty = tty;
567 tty->disc_data = sl;
568 sl->line = tty_devnum(tty);
569 sl->pid = current->pid;
570
571 if (!test_bit(SLF_INUSE, &sl->flags)) {
572 /* Perform the low-level SLCAN initialization. */
573 sl->rcount = 0;
574 sl->xleft = 0;
575
576 set_bit(SLF_INUSE, &sl->flags);
577
578 err = register_netdevice(sl->dev);
579 if (err)
580 goto err_free_chan;
581 }
582
583 /* Done. We have linked the TTY line to a channel. */
584 rtnl_unlock();
585 tty->receive_room = 65536; /* We don't flow control */
Oliver Hartkopp0d4420a2011-05-10 13:12:30 -0700586
587 /* TTY layer expects 0 on success */
588 return 0;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000589
590err_free_chan:
591 sl->tty = NULL;
592 tty->disc_data = NULL;
593 clear_bit(SLF_INUSE, &sl->flags);
594
595err_exit:
596 rtnl_unlock();
597
598 /* Count references from TTY module */
599 return err;
600}
601
602/*
603 * Close down a SLCAN channel.
604 * This means flushing out any pending queues, and then returning. This
605 * call is serialized against other ldisc functions.
606 *
607 * We also use this method for a hangup event.
608 */
609
610static void slcan_close(struct tty_struct *tty)
611{
612 struct slcan *sl = (struct slcan *) tty->disc_data;
613
614 /* First make sure we're connected. */
615 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
616 return;
617
618 tty->disc_data = NULL;
619 sl->tty = NULL;
620 if (!sl->leased)
621 sl->line = 0;
622
623 /* Flush network side */
624 unregister_netdev(sl->dev);
625 /* This will complete via sl_free_netdev */
626}
627
628static int slcan_hangup(struct tty_struct *tty)
629{
630 slcan_close(tty);
631 return 0;
632}
633
634/* Perform I/O control on an active SLCAN channel. */
635static int slcan_ioctl(struct tty_struct *tty, struct file *file,
636 unsigned int cmd, unsigned long arg)
637{
638 struct slcan *sl = (struct slcan *) tty->disc_data;
639 unsigned int tmp;
640
641 /* First make sure we're connected. */
642 if (!sl || sl->magic != SLCAN_MAGIC)
643 return -EINVAL;
644
645 switch (cmd) {
646 case SIOCGIFNAME:
647 tmp = strlen(sl->dev->name) + 1;
648 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
649 return -EFAULT;
650 return 0;
651
652 case SIOCSIFHWADDR:
653 return -EINVAL;
654
655 default:
656 return tty_mode_ioctl(tty, file, cmd, arg);
657 }
658}
659
660static struct tty_ldisc_ops slc_ldisc = {
661 .owner = THIS_MODULE,
662 .magic = TTY_LDISC_MAGIC,
663 .name = "slcan",
664 .open = slcan_open,
665 .close = slcan_close,
666 .hangup = slcan_hangup,
667 .ioctl = slcan_ioctl,
668 .receive_buf = slcan_receive_buf,
669 .write_wakeup = slcan_write_wakeup,
670};
671
672static int __init slcan_init(void)
673{
674 int status;
675
676 if (maxdev < 4)
677 maxdev = 4; /* Sanity */
678
679 printk(banner);
680 printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev);
681
682 slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
683 if (!slcan_devs) {
684 printk(KERN_ERR "slcan: can't allocate slcan device array!\n");
685 return -ENOMEM;
686 }
687
688 /* Fill in our line protocol discipline, and register it */
689 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
690 if (status) {
691 printk(KERN_ERR "slcan: can't register line discipline\n");
692 kfree(slcan_devs);
693 }
694 return status;
695}
696
697static void __exit slcan_exit(void)
698{
699 int i;
700 struct net_device *dev;
701 struct slcan *sl;
702 unsigned long timeout = jiffies + HZ;
703 int busy = 0;
704
705 if (slcan_devs == NULL)
706 return;
707
708 /* First of all: check for active disciplines and hangup them.
709 */
710 do {
711 if (busy)
712 msleep_interruptible(100);
713
714 busy = 0;
715 for (i = 0; i < maxdev; i++) {
716 dev = slcan_devs[i];
717 if (!dev)
718 continue;
719 sl = netdev_priv(dev);
720 spin_lock_bh(&sl->lock);
721 if (sl->tty) {
722 busy++;
723 tty_hangup(sl->tty);
724 }
725 spin_unlock_bh(&sl->lock);
726 }
727 } while (busy && time_before(jiffies, timeout));
728
729 /* FIXME: hangup is async so we should wait when doing this second
730 phase */
731
732 for (i = 0; i < maxdev; i++) {
733 dev = slcan_devs[i];
734 if (!dev)
735 continue;
736 slcan_devs[i] = NULL;
737
738 sl = netdev_priv(dev);
739 if (sl->tty) {
740 printk(KERN_ERR "%s: tty discipline still running\n",
741 dev->name);
742 /* Intentionally leak the control block. */
743 dev->destructor = NULL;
744 }
745
746 unregister_netdev(dev);
747 }
748
749 kfree(slcan_devs);
750 slcan_devs = NULL;
751
752 i = tty_unregister_ldisc(N_SLCAN);
753 if (i)
754 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
755}
756
757module_init(slcan_init);
758module_exit(slcan_exit);