1 /*-
2 * (MPSAFE)
3 *
4 * ng_tty.c
5 *
6 * Copyright (c) 1996-1999 Whistle Communications, Inc.
7 * All rights reserved.
8 *
9 * Subject to the following obligations and disclaimer of warranty, use and
10 * redistribution of this software, in source or object code forms, with or
11 * without modifications are expressly permitted by Whistle Communications;
12 * provided, however, that:
13 * 1. Any and all reproductions of the source or object code must include the
14 * copyright notice above and the following disclaimer of warranties; and
15 * 2. No rights are granted, in any manner or form, to use Whistle
16 * Communications, Inc. trademarks, including the mark "WHISTLE
17 * COMMUNICATIONS" on advertising, endorsements, or otherwise except as
18 * such appears in the above copyright notice or in the software.
19 *
20 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
21 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
22 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
23 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
24 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
25 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
26 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
27 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
28 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
29 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
30 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
31 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
32 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER 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 OF
35 * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
36 * OF SUCH DAMAGE.
37 *
38 * Author: Archie Cobbs <archie@freebsd.org>
39 *
40 * $FreeBSD: src/sys/netgraph/ng_tty.c,v 1.37 2006/11/06 13:42:03 rwatson Exp $
41 * $Whistle: ng_tty.c,v 1.21 1999/11/01 09:24:52 julian Exp $
42 */
43
44 /*
45 * This file implements a terminal line discipline that is also a
46 * netgraph node. Installing this line discipline on a terminal device
47 * instantiates a new netgraph node of this type, which allows access
48 * to the device via the "hook" hook of the node.
49 *
50 * Once the line discipline is installed, you can find out the name
51 * of the corresponding netgraph node via a NGIOCGINFO ioctl().
52 *
53 * Incoming characters are delievered to the hook one at a time, each
54 * in its own mbuf. You may optionally define a ``hotchar,'' which causes
55 * incoming characters to be buffered up until either the hotchar is
56 * seen or the mbuf is full (MHLEN bytes). Then all buffered characters
57 * are immediately delivered.
58 */
59
60 #include <sys/param.h>
61 #include <sys/systm.h>
62 #include <sys/conf.h>
63 #include <sys/errno.h>
64 #include <sys/fcntl.h>
65 #include <sys/kernel.h>
66 #include <sys/malloc.h>
67 #include <sys/mbuf.h>
68 #include <sys/caps.h>
69 #include <sys/socket.h>
70 #include <sys/syslog.h>
71 #include <sys/tty.h>
72 #include <sys/ttycom.h>
73
74 #include <net/if.h>
75 #include <net/if_var.h>
76
77 #include <netgraph7/netgraph.h>
78 #include <netgraph7/ng_message.h>
79 #include "ng_tty.h"
80
81 /* Misc defs */
82 #define MAX_MBUFQ 3 /* Max number of queued mbufs */
83 #define NGT_HIWATER 400 /* High water mark on output */
84
85 /* Per-node private info */
86 struct ngt_sc {
87 struct tty *tp; /* Terminal device */
88 node_p node; /* Netgraph node */
89 hook_p hook; /* Netgraph hook */
90 struct ifqueue outq; /* Queue of outgoing data */
91 struct mbuf *m; /* Incoming data buffer */
92 short hotchar; /* Hotchar, or -1 if none */
93 u_int flags; /* Flags */
94 struct callout chand; /* See man timeout(9) */
95 };
96 typedef struct ngt_sc *sc_p;
97
98 /* Flags */
99 #define FLG_DEBUG 0x0002
100 #define FLG_DIE 0x0004
101
102 /* Line discipline methods */
103 static int ngt_open(struct cdev *dev, struct tty *tp);
104 static int ngt_close(struct tty *tp, int flag);
105 static int ngt_read(struct tty *tp, struct uio *uio, int flag);
106 static int ngt_write(struct tty *tp, struct uio *uio, int flag);
107 static int ngt_tioctl(struct tty *tp,
108 u_long cmd, caddr_t data, int flag, struct ucred *cred);
109 static int ngt_input(int c, struct tty *tp);
110 static int ngt_start(struct tty *tp);
111
112 /* Netgraph methods */
113 static ng_constructor_t ngt_constructor;
114 static ng_rcvmsg_t ngt_rcvmsg;
115 static ng_shutdown_t ngt_shutdown;
116 static ng_newhook_t ngt_newhook;
117 static ng_connect_t ngt_connect;
118 static ng_rcvdata_t ngt_rcvdata;
119 static ng_disconnect_t ngt_disconnect;
120 static int ngt_mod_event(module_t mod, int event, void *data);
121
122 /* Other stuff */
123 static void ngt_timeout(node_p node, hook_p hook, void *arg1, int arg2);
124
125 #define ERROUT(x) do { error = (x); goto done; } while (0)
126
127 /* Line discipline descriptor */
128 static struct linesw ngt_disc = {
129 .l_open = ngt_open,
130 .l_close = ngt_close,
131 .l_read = ngt_read,
132 .l_write = ngt_write,
133 .l_ioctl = ngt_tioctl,
134 .l_rint = ngt_input,
135 .l_start = ngt_start,
136 .l_modem = ttymodem,
137 };
138
139 /* Netgraph node type descriptor */
140 static struct ng_type typestruct = {
141 .version = NG_ABI_VERSION,
142 .name = NG_TTY_NODE_TYPE,
143 .mod_event = ngt_mod_event,
144 .constructor = ngt_constructor,
145 .rcvmsg = ngt_rcvmsg,
146 .shutdown = ngt_shutdown,
147 .newhook = ngt_newhook,
148 .connect = ngt_connect,
149 .rcvdata = ngt_rcvdata,
150 .disconnect = ngt_disconnect,
151 };
152 NETGRAPH_INIT(tty, &typestruct);
153
154 /*
155 * Locking:
156 *
157 * - node private data and tp->t_lsc is protected by mutex in struct
158 * ifqueue, locking is done using IF_XXX() macros.
159 * - in all tty methods we should acquire node ifqueue mutex, when accessing
160 * private data.
161 * - in _rcvdata() we should use locked versions of IF_{EN,DE}QUEUE() since
162 * we may have multiple _rcvdata() threads.
163 * - when calling any of tty methods from netgraph methods, we should
164 * acquire tty locking (now Giant).
165 *
166 * - ngt_unit is incremented atomically.
167 */
168
169 static int ngt_unit;
170 static int ngt_ldisc;
171
172 /******************************************************************
173 LINE DISCIPLINE METHODS
174 ******************************************************************/
175
176 /*
177 * Set our line discipline on the tty.
178 * Called from device open routine or ttioctl()
179 */
180 static int
ngt_open(struct cdev * dev,struct tty * tp)181 ngt_open(struct cdev *dev, struct tty *tp)
182 {
183 char name[sizeof(NG_TTY_NODE_TYPE) + 8];
184 sc_p sc;
185 int error;
186
187 /* Super-user only */
188 error = caps_priv_check_self(SYSCAP_NONET_NETGRAPH);
189 if (error)
190 return (error);
191
192 /* Initialize private struct */
193 sc = kmalloc(sizeof(*sc), M_NETGRAPH, M_WAITOK | M_ZERO);
194
195 lwkt_gettoken(&tp->t_token);
196 sc->tp = tp;
197 sc->hotchar = NG_TTY_DFL_HOTCHAR;
198 sc->outq.ifq_maxlen = MAX_MBUFQ;
199
200 /* Setup netgraph node */
201 error = ng_make_node_common(&typestruct, &sc->node);
202 if (error) {
203 kfree(sc, M_NETGRAPH);
204 lwkt_reltoken(&tp->t_token);
205 return (error);
206 }
207
208 atomic_add_int(&ngt_unit, 1);
209 ksnprintf(name, sizeof(name), "%s%d", typestruct.name, ngt_unit);
210
211 /* Assign node its name */
212 if ((error = ng_name_node(sc->node, name))) {
213 sc->flags |= FLG_DIE;
214 NG_NODE_UNREF(sc->node);
215 log(LOG_ERR, "%s: node name exists?\n", name);
216 lwkt_reltoken(&tp->t_token);
217 return (error);
218 }
219
220 /* Set back pointers */
221 NG_NODE_SET_PRIVATE(sc->node, sc);
222 tp->t_sc = sc;
223
224 callout_init_mp(&sc->chand);
225
226 /*
227 * Pre-allocate cblocks to the an appropriate amount.
228 * I'm not sure what is appropriate.
229 */
230 ttyflush(tp, FREAD | FWRITE);
231 clist_alloc_cblocks(&tp->t_canq, 0);
232 clist_alloc_cblocks(&tp->t_rawq, 0);
233 clist_alloc_cblocks(&tp->t_outq, MLEN + NGT_HIWATER);
234
235 lwkt_reltoken(&tp->t_token);
236 return (error);
237 }
238
239 /*
240 * Line specific close routine, called from device close routine
241 * and from ttioctl. This causes the node to be destroyed as well.
242 */
243 static int
ngt_close(struct tty * tp,int flag)244 ngt_close(struct tty *tp, int flag)
245 {
246 const sc_p sc = (sc_p) tp->t_sc;
247
248 lwkt_gettoken(&tp->t_token);
249 ttyflush(tp, FREAD | FWRITE);
250 clist_free_cblocks(&tp->t_outq);
251 if (sc != NULL) {
252 if (callout_pending(&sc->chand))
253 ng_uncallout(&sc->chand, sc->node);
254 tp->t_sc = NULL;
255 sc->flags |= FLG_DIE;
256 ng_rmnode_self(sc->node);
257 }
258 lwkt_reltoken(&tp->t_token);
259 return (0);
260 }
261
262 /*
263 * Once the device has been turned into a node, we don't allow reading.
264 */
265 static int
ngt_read(struct tty * tp,struct uio * uio,int flag)266 ngt_read(struct tty *tp, struct uio *uio, int flag)
267 {
268 return (EIO);
269 }
270
271 /*
272 * Once the device has been turned into a node, we don't allow writing.
273 */
274 static int
ngt_write(struct tty * tp,struct uio * uio,int flag)275 ngt_write(struct tty *tp, struct uio *uio, int flag)
276 {
277 return (EIO);
278 }
279
280 /*
281 * We implement the NGIOCGINFO ioctl() defined in ng_message.h.
282 */
283 static int
ngt_tioctl(struct tty * tp,u_long cmd,caddr_t data,int flag,struct ucred * cred)284 ngt_tioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct ucred *cred)
285 {
286 const sc_p sc = (sc_p) tp->t_sc;
287
288 if (sc == NULL) {
289 /* No node attached */
290 return (0);
291 }
292
293 lwkt_gettoken(&tp->t_token);
294 switch (cmd) {
295 case NGIOCGINFO:
296 {
297 struct nodeinfo *const ni = (struct nodeinfo *) data;
298 const node_p node = sc->node;
299
300 bzero(ni, sizeof(*ni));
301 if (NG_NODE_HAS_NAME(node))
302 strncpy(ni->name, NG_NODE_NAME(node), sizeof(ni->name) - 1);
303 strncpy(ni->type, node->nd_type->name, sizeof(ni->type) - 1);
304 ni->id = (u_int32_t) ng_node2ID(node);
305 ni->hooks = NG_NODE_NUMHOOKS(node);
306 break;
307 }
308 default:
309 lwkt_reltoken(&tp->t_token);
310 return (ENOIOCTL);
311 }
312
313 lwkt_reltoken(&tp->t_token);
314 return (0);
315 }
316
317 /*
318 * Receive data coming from the device. We get one character at
319 * a time, which is kindof silly.
320 *
321 * Full locking of softc is not required, since we are the only
322 * user of sc->m.
323 */
324 static int
ngt_input(int c,struct tty * tp)325 ngt_input(int c, struct tty *tp)
326 {
327 sc_p sc;
328 node_p node;
329 struct mbuf *m;
330 int error = 0;
331
332 lwkt_gettoken(&tp->t_token);
333 sc = (sc_p) tp->t_sc;
334 if (sc == NULL) {
335 /* No node attached */
336 lwkt_reltoken(&tp->t_token);
337 return (0);
338 }
339
340 node = sc->node;
341
342 if (tp != sc->tp)
343 panic("ngt_input");
344
345 /* Check for error conditions */
346 if ((tp->t_state & TS_CONNECTED) == 0) {
347 if (sc->flags & FLG_DEBUG)
348 log(LOG_DEBUG, "%s: no carrier\n", NG_NODE_NAME(node));
349 lwkt_reltoken(&tp->t_token);
350 return (0);
351 }
352 if (c & TTY_ERRORMASK) {
353 /* framing error or overrun on this char */
354 if (sc->flags & FLG_DEBUG)
355 log(LOG_DEBUG, "%s: line error %x\n",
356 NG_NODE_NAME(node), c & TTY_ERRORMASK);
357 lwkt_reltoken(&tp->t_token);
358 return (0);
359 }
360 c &= TTY_CHARMASK;
361
362 /* Get a new header mbuf if we need one */
363 if (!(m = sc->m)) {
364 MGETHDR(m, M_NOWAIT, MT_DATA);
365 if (!m) {
366 if (sc->flags & FLG_DEBUG)
367 log(LOG_ERR,
368 "%s: can't get mbuf\n", NG_NODE_NAME(node));
369 lwkt_reltoken(&tp->t_token);
370 return (ENOBUFS);
371 }
372 m->m_len = m->m_pkthdr.len = 0;
373 m->m_pkthdr.rcvif = NULL;
374 sc->m = m;
375 }
376
377 /* Add char to mbuf */
378 *mtod(m, u_char *) = c;
379 m->m_data++;
380 m->m_len++;
381 m->m_pkthdr.len++;
382
383 /* Ship off mbuf if it's time */
384 if (sc->hotchar == -1 || c == sc->hotchar || m->m_len >= MHLEN) {
385 m->m_data = m->m_pktdat;
386 sc->m = NULL;
387
388 /*
389 * We have built our mbuf without checking that we actually
390 * have a hook to send it. This was done to avoid
391 * acquiring mutex on each character. Check now.
392 *
393 */
394
395 if (sc->hook == NULL) {
396 m_freem(m);
397 lwkt_reltoken(&tp->t_token);
398 return (0); /* XXX: original behavior */
399 }
400 NG_SEND_DATA_ONLY(error, sc->hook, m); /* Will queue */
401 }
402
403 lwkt_reltoken(&tp->t_token);
404 return (error);
405 }
406
407 /*
408 * This is called when the device driver is ready for more output.
409 * Also called from ngt_rcv_data() when a new mbuf is available for output.
410 */
411 static int
ngt_start(struct tty * tp)412 ngt_start(struct tty *tp)
413 {
414 const sc_p sc = (sc_p) tp->t_sc;
415
416 lwkt_gettoken(&tp->t_token);
417 while (tp->t_outq.c_cc < NGT_HIWATER) { /* XXX 2.2 specific ? */
418 struct mbuf *m;
419
420 /* Remove first mbuf from queue */
421 IF_DEQUEUE(&sc->outq, m);
422 if (m == NULL)
423 break;
424
425 /* Send as much of it as possible */
426 while (m != NULL) {
427 int sent;
428
429 sent = m->m_len - clist_btoq(mtod(m, u_char *),
430 m->m_len, &tp->t_outq);
431 m->m_data += sent;
432 m->m_len -= sent;
433 if (m->m_len > 0)
434 break; /* device can't take no more */
435 m = m_free(m);
436 }
437
438 /* Put remainder of mbuf chain (if any) back on queue */
439 if (m != NULL) {
440 IF_PREPEND(&sc->outq, m);
441 break;
442 }
443 }
444
445 /* Call output process whether or not there is any output. We are
446 * being called in lieu of ttstart and must do what it would. */
447 if (tp->t_oproc != NULL)
448 (*tp->t_oproc) (tp);
449
450 /* This timeout is needed for operation on a pseudo-tty, because the
451 * pty code doesn't call pppstart after it has drained the t_outq. */
452 /* XXX: outq not locked */
453 if (!IF_QEMPTY(&sc->outq) && !callout_pending(&sc->chand))
454 ng_callout(&sc->chand, sc->node, NULL, 1, ngt_timeout, NULL, 0);
455
456 lwkt_reltoken(&tp->t_token);
457 return (0);
458 }
459
460 /*
461 * We still have data to output to the device, so try sending more.
462 */
463 static void
ngt_timeout(node_p node,hook_p hook,void * arg1,int arg2)464 ngt_timeout(node_p node, hook_p hook, void *arg1, int arg2)
465 {
466 const sc_p sc = NG_NODE_PRIVATE(node);
467 struct tty *tp = sc->tp;
468
469 lwkt_gettoken(&tp->t_token);
470 ngt_start(sc->tp);
471 lwkt_reltoken(&tp->t_token);
472 }
473
474 /******************************************************************
475 NETGRAPH NODE METHODS
476 ******************************************************************/
477
478 /*
479 * Initialize a new node of this type.
480 *
481 * We only allow nodes to be created as a result of setting
482 * the line discipline on a tty, so always return an error if not.
483 */
484 static int
ngt_constructor(node_p node)485 ngt_constructor(node_p node)
486 {
487 return (EOPNOTSUPP);
488 }
489
490 /*
491 * Add a new hook. There can only be one.
492 */
493 static int
ngt_newhook(node_p node,hook_p hook,const char * name)494 ngt_newhook(node_p node, hook_p hook, const char *name)
495 {
496 const sc_p sc = NG_NODE_PRIVATE(node);
497 struct tty *tp = sc->tp;
498
499 if (strcmp(name, NG_TTY_HOOK))
500 return (EINVAL);
501 lwkt_gettoken(&tp->t_token);
502 if (sc->hook) {
503 lwkt_reltoken(&tp->t_token);
504 return (EISCONN);
505 }
506 sc->hook = hook;
507 lwkt_reltoken(&tp->t_token);
508 return (0);
509 }
510
511 /*
512 * Set the hook into queueing mode (for outgoing packets),
513 * so that we wont deliver mbuf thru the whole graph holding
514 * tty locks.
515 */
516 static int
ngt_connect(hook_p hook)517 ngt_connect(hook_p hook)
518 {
519 NG_HOOK_FORCE_QUEUE(NG_HOOK_PEER(hook));
520 /*
521 * XXX: While ngt_start() is Giant-locked, queue incoming
522 * packets, too. Otherwise we acquire Giant holding some
523 * IP stack locks, e.g. divinp, and this makes WITNESS scream.
524 */
525 NG_HOOK_FORCE_QUEUE(hook);
526 return (0);
527 }
528
529 /*
530 * Disconnect the hook
531 */
532 static int
ngt_disconnect(hook_p hook)533 ngt_disconnect(hook_p hook)
534 {
535 const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
536 struct tty *tp = sc->tp;
537
538 lwkt_gettoken(&tp->t_token);
539 if (hook != sc->hook)
540 panic(__func__);
541 sc->hook = NULL;
542 lwkt_reltoken(&tp->t_token);
543 return (0);
544 }
545
546 /*
547 * Remove this node. The does the netgraph portion of the shutdown.
548 * This should only be called indirectly from ngt_close().
549 *
550 * tp->t_lsc is already NULL, so we should be protected from
551 * tty calls now.
552 */
553 static int
ngt_shutdown(node_p node)554 ngt_shutdown(node_p node)
555 {
556 const sc_p sc = NG_NODE_PRIVATE(node);
557 struct tty *tp = sc->tp;
558
559 lwkt_gettoken(&tp->t_token);
560 if (!(sc->flags & FLG_DIE)) {
561 lwkt_reltoken(&tp->t_token);
562 return (EOPNOTSUPP);
563 }
564
565 /* Free resources */
566 IF_DRAIN(&sc->outq);
567 m_freem(sc->m);
568 kfree(sc, M_NETGRAPH);
569 lwkt_reltoken(&tp->t_token);
570 return (0);
571 }
572
573 /*
574 * Receive incoming data from netgraph system. Put it on our
575 * output queue and start output if necessary.
576 */
577 static int
ngt_rcvdata(hook_p hook,item_p item)578 ngt_rcvdata(hook_p hook, item_p item)
579 {
580 const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
581 struct tty *tp = sc->tp;
582 struct mbuf *m;
583 int qlen;
584
585 if (hook != sc->hook)
586 panic(__func__);
587
588 NGI_GET_M(item, m);
589 NG_FREE_ITEM(item);
590
591 if (IF_QFULL(&sc->outq)) {
592 IF_DROP(&sc->outq);
593 NG_FREE_M(m);
594 return (ENOBUFS);
595 }
596
597 IF_ENQUEUE(&sc->outq, m);
598 qlen = sc->outq.ifq_len;
599
600 /*
601 * If qlen > 1, then we should already have a scheduled callout.
602 */
603 if (qlen == 1) {
604 lwkt_gettoken(&tp->t_token);
605 ngt_start(sc->tp);
606 lwkt_reltoken(&tp->t_token);
607 }
608
609 return (0);
610 }
611
612 /*
613 * Receive control message
614 */
615 static int
ngt_rcvmsg(node_p node,item_p item,hook_p lasthook)616 ngt_rcvmsg(node_p node, item_p item, hook_p lasthook)
617 {
618 const sc_p sc = NG_NODE_PRIVATE(node);
619 struct ng_mesg *msg, *resp = NULL;
620 int error = 0;
621
622 NGI_GET_MSG(item, msg);
623 switch (msg->header.typecookie) {
624 case NGM_TTY_COOKIE:
625 switch (msg->header.cmd) {
626 case NGM_TTY_SET_HOTCHAR:
627 {
628 int hotchar;
629
630 if (msg->header.arglen != sizeof(int))
631 ERROUT(EINVAL);
632 hotchar = *((int *) msg->data);
633 if (hotchar != (u_char) hotchar && hotchar != -1)
634 ERROUT(EINVAL);
635 sc->hotchar = hotchar; /* race condition is OK */
636 break;
637 }
638 case NGM_TTY_GET_HOTCHAR:
639 NG_MKRESPONSE(resp, msg, sizeof(int), M_WAITOK | M_NULLOK);
640 if (!resp)
641 ERROUT(ENOMEM);
642 /* Race condition here is OK */
643 *((int *) resp->data) = sc->hotchar;
644 break;
645 default:
646 ERROUT(EINVAL);
647 }
648 break;
649 default:
650 ERROUT(EINVAL);
651 }
652 done:
653 NG_RESPOND_MSG(error, node, item, resp);
654 NG_FREE_MSG(msg);
655 return (error);
656 }
657
658 /******************************************************************
659 INITIALIZATION
660 ******************************************************************/
661
662 /*
663 * Handle loading and unloading for this node type
664 */
665 static int
ngt_mod_event(module_t mod,int event,void * data)666 ngt_mod_event(module_t mod, int event, void *data)
667 {
668 int error = 0;
669
670 switch (event) {
671 case MOD_LOAD:
672 /* Register line discipline */
673 if ((ngt_ldisc = ldisc_register(NETGRAPHDISC, &ngt_disc)) < 0) {
674 log(LOG_ERR, "%s: can't register line discipline",
675 __func__);
676 return (EIO);
677 }
678 break;
679
680 case MOD_UNLOAD:
681
682 /* Unregister line discipline */
683 ldisc_deregister(ngt_ldisc);
684 break;
685
686 default:
687 error = EOPNOTSUPP;
688 break;
689 }
690 return (error);
691 }
692