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/priv.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 181 ngt_open(struct cdev *dev, struct tty *tp) 182 { 183 struct thread *const td = curthread; /* XXX */ 184 char name[sizeof(NG_TTY_NODE_TYPE) + 8]; 185 sc_p sc; 186 int error; 187 188 /* Super-user only */ 189 error = priv_check(td, PRIV_NETGRAPH_TTY); 190 if (error) 191 return (error); 192 193 /* Initialize private struct */ 194 sc = kmalloc(sizeof(*sc), M_NETGRAPH, M_WAITOK | M_ZERO); 195 196 crit_enter(); 197 lwkt_gettoken(&tty_token); 198 sc->tp = tp; 199 sc->hotchar = NG_TTY_DFL_HOTCHAR; 200 sc->outq.ifq_maxlen = MAX_MBUFQ; 201 202 /* Setup netgraph node */ 203 error = ng_make_node_common(&typestruct, &sc->node); 204 if (error) { 205 kfree(sc, M_NETGRAPH); 206 lwkt_reltoken(&tty_token); 207 crit_exit(); 208 return (error); 209 } 210 211 atomic_add_int(&ngt_unit, 1); 212 ksnprintf(name, sizeof(name), "%s%d", typestruct.name, ngt_unit); 213 214 /* Assign node its name */ 215 if ((error = ng_name_node(sc->node, name))) { 216 sc->flags |= FLG_DIE; 217 NG_NODE_UNREF(sc->node); 218 log(LOG_ERR, "%s: node name exists?\n", name); 219 lwkt_reltoken(&tty_token); 220 crit_exit(); 221 return (error); 222 } 223 224 /* Set back pointers */ 225 NG_NODE_SET_PRIVATE(sc->node, sc); 226 tp->t_sc = sc; 227 228 callout_init_mp(&sc->chand); 229 230 /* 231 * Pre-allocate cblocks to the an appropriate amount. 232 * I'm not sure what is appropriate. 233 */ 234 ttyflush(tp, FREAD | FWRITE); 235 clist_alloc_cblocks(&tp->t_canq, 0, 0); 236 clist_alloc_cblocks(&tp->t_rawq, 0, 0); 237 clist_alloc_cblocks(&tp->t_outq, 238 MLEN + NGT_HIWATER, MLEN + NGT_HIWATER); 239 240 lwkt_reltoken(&tty_token); 241 crit_exit(); 242 return (error); 243 } 244 245 /* 246 * Line specific close routine, called from device close routine 247 * and from ttioctl. This causes the node to be destroyed as well. 248 */ 249 static int 250 ngt_close(struct tty *tp, int flag) 251 { 252 const sc_p sc = (sc_p) tp->t_sc; 253 254 crit_enter(); 255 lwkt_gettoken(&tty_token); 256 ttyflush(tp, FREAD | FWRITE); 257 clist_free_cblocks(&tp->t_outq); 258 if (sc != NULL) { 259 if (callout_pending(&sc->chand)) 260 ng_uncallout(&sc->chand, sc->node); 261 tp->t_sc = NULL; 262 sc->flags |= FLG_DIE; 263 ng_rmnode_self(sc->node); 264 } 265 lwkt_reltoken(&tty_token); 266 crit_exit(); 267 return (0); 268 } 269 270 /* 271 * Once the device has been turned into a node, we don't allow reading. 272 */ 273 static int 274 ngt_read(struct tty *tp, struct uio *uio, int flag) 275 { 276 return (EIO); 277 } 278 279 /* 280 * Once the device has been turned into a node, we don't allow writing. 281 */ 282 static int 283 ngt_write(struct tty *tp, struct uio *uio, int flag) 284 { 285 return (EIO); 286 } 287 288 /* 289 * We implement the NGIOCGINFO ioctl() defined in ng_message.h. 290 */ 291 static int 292 ngt_tioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct ucred *cred) 293 { 294 const sc_p sc = (sc_p) tp->t_sc; 295 296 if (sc == NULL) { 297 /* No node attached */ 298 return (0); 299 } 300 301 crit_enter(); 302 lwkt_gettoken(&tty_token); 303 switch (cmd) { 304 case NGIOCGINFO: 305 { 306 struct nodeinfo *const ni = (struct nodeinfo *) data; 307 const node_p node = sc->node; 308 309 bzero(ni, sizeof(*ni)); 310 if (NG_NODE_HAS_NAME(node)) 311 strncpy(ni->name, NG_NODE_NAME(node), sizeof(ni->name) - 1); 312 strncpy(ni->type, node->nd_type->name, sizeof(ni->type) - 1); 313 ni->id = (u_int32_t) ng_node2ID(node); 314 ni->hooks = NG_NODE_NUMHOOKS(node); 315 break; 316 } 317 default: 318 lwkt_reltoken(&tty_token); 319 crit_exit(); 320 return (ENOIOCTL); 321 } 322 323 lwkt_reltoken(&tty_token); 324 crit_exit(); 325 return (0); 326 } 327 328 /* 329 * Receive data coming from the device. We get one character at 330 * a time, which is kindof silly. 331 * 332 * Full locking of softc is not required, since we are the only 333 * user of sc->m. 334 */ 335 static int 336 ngt_input(int c, struct tty *tp) 337 { 338 sc_p sc; 339 node_p node; 340 struct mbuf *m; 341 int error = 0; 342 343 crit_enter(); 344 lwkt_gettoken(&tty_token); 345 sc = (sc_p) tp->t_sc; 346 if (sc == NULL) { 347 /* No node attached */ 348 lwkt_reltoken(&tty_token); 349 crit_exit(); 350 return (0); 351 } 352 353 node = sc->node; 354 355 if (tp != sc->tp) 356 panic("ngt_input"); 357 358 /* Check for error conditions */ 359 if ((tp->t_state & TS_CONNECTED) == 0) { 360 if (sc->flags & FLG_DEBUG) 361 log(LOG_DEBUG, "%s: no carrier\n", NG_NODE_NAME(node)); 362 lwkt_reltoken(&tty_token); 363 crit_exit(); 364 return (0); 365 } 366 if (c & TTY_ERRORMASK) { 367 /* framing error or overrun on this char */ 368 if (sc->flags & FLG_DEBUG) 369 log(LOG_DEBUG, "%s: line error %x\n", 370 NG_NODE_NAME(node), c & TTY_ERRORMASK); 371 lwkt_reltoken(&tty_token); 372 crit_exit(); 373 return (0); 374 } 375 c &= TTY_CHARMASK; 376 377 /* Get a new header mbuf if we need one */ 378 if (!(m = sc->m)) { 379 MGETHDR(m, M_NOWAIT, MT_DATA); 380 if (!m) { 381 if (sc->flags & FLG_DEBUG) 382 log(LOG_ERR, 383 "%s: can't get mbuf\n", NG_NODE_NAME(node)); 384 lwkt_reltoken(&tty_token); 385 crit_exit(); 386 return (ENOBUFS); 387 } 388 m->m_len = m->m_pkthdr.len = 0; 389 m->m_pkthdr.rcvif = NULL; 390 sc->m = m; 391 } 392 393 /* Add char to mbuf */ 394 *mtod(m, u_char *) = c; 395 m->m_data++; 396 m->m_len++; 397 m->m_pkthdr.len++; 398 399 /* Ship off mbuf if it's time */ 400 if (sc->hotchar == -1 || c == sc->hotchar || m->m_len >= MHLEN) { 401 m->m_data = m->m_pktdat; 402 sc->m = NULL; 403 404 /* 405 * We have built our mbuf without checking that we actually 406 * have a hook to send it. This was done to avoid 407 * acquiring mutex on each character. Check now. 408 * 409 */ 410 411 if (sc->hook == NULL) { 412 m_freem(m); 413 lwkt_reltoken(&tty_token); 414 crit_exit(); 415 return (0); /* XXX: original behavior */ 416 } 417 NG_SEND_DATA_ONLY(error, sc->hook, m); /* Will queue */ 418 } 419 420 lwkt_reltoken(&tty_token); 421 crit_exit(); 422 return (error); 423 } 424 425 /* 426 * This is called when the device driver is ready for more output. 427 * Also called from ngt_rcv_data() when a new mbuf is available for output. 428 */ 429 static int 430 ngt_start(struct tty *tp) 431 { 432 const sc_p sc = (sc_p) tp->t_sc; 433 434 crit_enter(); 435 lwkt_gettoken(&tty_token); 436 while (tp->t_outq.c_cc < NGT_HIWATER) { /* XXX 2.2 specific ? */ 437 struct mbuf *m; 438 439 /* Remove first mbuf from queue */ 440 IF_DEQUEUE(&sc->outq, m); 441 if (m == NULL) 442 break; 443 444 /* Send as much of it as possible */ 445 while (m != NULL) { 446 int sent; 447 448 sent = m->m_len 449 - b_to_q(mtod(m, u_char *), m->m_len, &tp->t_outq); 450 m->m_data += sent; 451 m->m_len -= sent; 452 if (m->m_len > 0) 453 break; /* device can't take no more */ 454 m = m_free(m); 455 } 456 457 /* Put remainder of mbuf chain (if any) back on queue */ 458 if (m != NULL) { 459 IF_PREPEND(&sc->outq, m); 460 break; 461 } 462 } 463 464 /* Call output process whether or not there is any output. We are 465 * being called in lieu of ttstart and must do what it would. */ 466 if (tp->t_oproc != NULL) 467 (*tp->t_oproc) (tp); 468 469 /* This timeout is needed for operation on a pseudo-tty, because the 470 * pty code doesn't call pppstart after it has drained the t_outq. */ 471 /* XXX: outq not locked */ 472 if (!IF_QEMPTY(&sc->outq) && !callout_pending(&sc->chand)) 473 ng_callout(&sc->chand, sc->node, NULL, 1, ngt_timeout, NULL, 0); 474 475 lwkt_reltoken(&tty_token); 476 crit_exit(); 477 return (0); 478 } 479 480 /* 481 * We still have data to output to the device, so try sending more. 482 */ 483 static void 484 ngt_timeout(node_p node, hook_p hook, void *arg1, int arg2) 485 { 486 const sc_p sc = NG_NODE_PRIVATE(node); 487 488 crit_enter(); 489 lwkt_gettoken(&tty_token); 490 ngt_start(sc->tp); 491 lwkt_reltoken(&tty_token); 492 crit_exit(); 493 } 494 495 /****************************************************************** 496 NETGRAPH NODE METHODS 497 ******************************************************************/ 498 499 /* 500 * Initialize a new node of this type. 501 * 502 * We only allow nodes to be created as a result of setting 503 * the line discipline on a tty, so always return an error if not. 504 */ 505 static int 506 ngt_constructor(node_p node) 507 { 508 return (EOPNOTSUPP); 509 } 510 511 /* 512 * Add a new hook. There can only be one. 513 */ 514 static int 515 ngt_newhook(node_p node, hook_p hook, const char *name) 516 { 517 const sc_p sc = NG_NODE_PRIVATE(node); 518 519 if (strcmp(name, NG_TTY_HOOK)) 520 return (EINVAL); 521 crit_enter(); 522 lwkt_gettoken(&tty_token); 523 if (sc->hook) { 524 lwkt_reltoken(&tty_token); 525 crit_exit(); 526 return (EISCONN); 527 } 528 sc->hook = hook; 529 lwkt_reltoken(&tty_token); 530 crit_exit(); 531 return (0); 532 } 533 534 /* 535 * Set the hook into queueing mode (for outgoing packets), 536 * so that we wont deliver mbuf thru the whole graph holding 537 * tty locks. 538 */ 539 static int 540 ngt_connect(hook_p hook) 541 { 542 NG_HOOK_FORCE_QUEUE(NG_HOOK_PEER(hook)); 543 /* 544 * XXX: While ngt_start() is Giant-locked, queue incoming 545 * packets, too. Otherwise we acquire Giant holding some 546 * IP stack locks, e.g. divinp, and this makes WITNESS scream. 547 */ 548 NG_HOOK_FORCE_QUEUE(hook); 549 return (0); 550 } 551 552 /* 553 * Disconnect the hook 554 */ 555 static int 556 ngt_disconnect(hook_p hook) 557 { 558 const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook)); 559 560 crit_enter(); 561 lwkt_gettoken(&tty_token); 562 if (hook != sc->hook) 563 panic(__func__); 564 sc->hook = NULL; 565 lwkt_reltoken(&tty_token); 566 crit_exit(); 567 return (0); 568 } 569 570 /* 571 * Remove this node. The does the netgraph portion of the shutdown. 572 * This should only be called indirectly from ngt_close(). 573 * 574 * tp->t_lsc is already NULL, so we should be protected from 575 * tty calls now. 576 */ 577 static int 578 ngt_shutdown(node_p node) 579 { 580 const sc_p sc = NG_NODE_PRIVATE(node); 581 582 crit_enter(); 583 lwkt_gettoken(&tty_token); 584 if (!(sc->flags & FLG_DIE)) { 585 lwkt_reltoken(&tty_token); 586 crit_exit(); 587 return (EOPNOTSUPP); 588 } 589 590 /* Free resources */ 591 IF_DRAIN(&sc->outq); 592 m_freem(sc->m); 593 kfree(sc, M_NETGRAPH); 594 lwkt_reltoken(&tty_token); 595 crit_exit(); 596 return (0); 597 } 598 599 /* 600 * Receive incoming data from netgraph system. Put it on our 601 * output queue and start output if necessary. 602 */ 603 static int 604 ngt_rcvdata(hook_p hook, item_p item) 605 { 606 const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook)); 607 struct mbuf *m; 608 int qlen; 609 610 if (hook != sc->hook) 611 panic(__func__); 612 613 NGI_GET_M(item, m); 614 NG_FREE_ITEM(item); 615 616 crit_enter(); 617 if (IF_QFULL(&sc->outq)) { 618 IF_DROP(&sc->outq); 619 crit_exit(); 620 NG_FREE_M(m); 621 return (ENOBUFS); 622 } 623 624 IF_ENQUEUE(&sc->outq, m); 625 qlen = sc->outq.ifq_len; 626 crit_exit(); 627 628 /* 629 * If qlen > 1, then we should already have a scheduled callout. 630 */ 631 if (qlen == 1) { 632 lwkt_gettoken(&tty_token); 633 ngt_start(sc->tp); 634 lwkt_reltoken(&tty_token); 635 } 636 637 return (0); 638 } 639 640 /* 641 * Receive control message 642 */ 643 static int 644 ngt_rcvmsg(node_p node, item_p item, hook_p lasthook) 645 { 646 const sc_p sc = NG_NODE_PRIVATE(node); 647 struct ng_mesg *msg, *resp = NULL; 648 int error = 0; 649 650 NGI_GET_MSG(item, msg); 651 switch (msg->header.typecookie) { 652 case NGM_TTY_COOKIE: 653 switch (msg->header.cmd) { 654 case NGM_TTY_SET_HOTCHAR: 655 { 656 int hotchar; 657 658 if (msg->header.arglen != sizeof(int)) 659 ERROUT(EINVAL); 660 hotchar = *((int *) msg->data); 661 if (hotchar != (u_char) hotchar && hotchar != -1) 662 ERROUT(EINVAL); 663 sc->hotchar = hotchar; /* race condition is OK */ 664 break; 665 } 666 case NGM_TTY_GET_HOTCHAR: 667 NG_MKRESPONSE(resp, msg, sizeof(int), M_WAITOK | M_NULLOK); 668 if (!resp) 669 ERROUT(ENOMEM); 670 /* Race condition here is OK */ 671 *((int *) resp->data) = sc->hotchar; 672 break; 673 default: 674 ERROUT(EINVAL); 675 } 676 break; 677 default: 678 ERROUT(EINVAL); 679 } 680 done: 681 NG_RESPOND_MSG(error, node, item, resp); 682 NG_FREE_MSG(msg); 683 return (error); 684 } 685 686 /****************************************************************** 687 INITIALIZATION 688 ******************************************************************/ 689 690 /* 691 * Handle loading and unloading for this node type 692 */ 693 static int 694 ngt_mod_event(module_t mod, int event, void *data) 695 { 696 int error = 0; 697 698 switch (event) { 699 case MOD_LOAD: 700 /* Register line discipline */ 701 crit_enter(); 702 if ((ngt_ldisc = ldisc_register(NETGRAPHDISC, &ngt_disc)) < 0) { 703 crit_exit(); 704 log(LOG_ERR, "%s: can't register line discipline", 705 __func__); 706 return (EIO); 707 } 708 crit_exit(); 709 break; 710 711 case MOD_UNLOAD: 712 713 /* Unregister line discipline */ 714 crit_enter(); 715 ldisc_deregister(ngt_ldisc); 716 crit_exit(); 717 break; 718 719 default: 720 error = EOPNOTSUPP; 721 break; 722 } 723 return (error); 724 } 725