/* $OpenBSD: kern_lkm.c,v 1.26 2000/01/02 06:28:06 assar Exp $ */ /* $NetBSD: kern_lkm.c,v 1.31 1996/03/31 21:40:27 christos Exp $ */ /* * Copyright (c) 1994 Christopher G. Demetriou * Copyright (c) 1992 Terrence R. Lambert. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by Terrence R. Lambert. * 4. The name Terrence R. Lambert may not be used to endorse or promote * products derived from this software without specific prior written * permission. * * THIS SOFTWARE IS PROVIDED BY TERRENCE R. LAMBERT ``AS IS'' AND ANY * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE TERRENCE R. LAMBERT BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* * XXX it's not really safe to unload *any* of the types which are * currently loadable; e.g. you could unload a syscall which was being * blocked in, etc. In the long term, a solution should be come up * with, but "not right now." -- cgd */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef DDB #include #include #endif #define LKM_ALLOC 0x01 #define LKM_WANT 0x02 #define LKMS_IDLE 0x00 #define LKMS_RESERVED 0x01 #define LKMS_LOADING 0x02 #define LKMS_LOADING_SYMS 0x03 #define LKMS_LOADED 0x04 #define LKMS_UNLOADING 0x08 static int lkm_v = 0; static int lkm_state = LKMS_IDLE; static TAILQ_HEAD(, lkm_table) lkmods; /* table of loaded modules */ static struct lkm_table *curp; /* global for in-progress ops */ static size_t nlkms = 0; /* number of loaded lkms */ static struct lkm_table *lkmalloc __P((void)); /* allocate new lkm table entry */ static void lkmfree __P((struct lkm_table *)); /* free it */ static struct lkm_table *lkmlookup __P((int, char *, int *)); static void lkmunreserve __P((void)); static int _lkm_syscall __P((struct lkm_table *, int)); static int _lkm_vfs __P((struct lkm_table *, int)); static int _lkm_dev __P((struct lkm_table *, int)); #ifdef STREAMS static int _lkm_strmod __P((struct lkm_table *, int)); #endif static int _lkm_exec __P((struct lkm_table *, int)); void lkminit __P((void)); int lkmexists __P((struct lkm_table *)); void lkminit() { TAILQ_INIT(&lkmods); } /*ARGSUSED*/ int lkmopen(dev, flag, devtype, p) dev_t dev; int flag; int devtype; struct proc *p; { int error; if (minor(dev) != 0) return (ENXIO); /* bad minor # */ /* * Use of the loadable kernel module device must be exclusive; we * may try to remove this restriction later, but it's really no * hardship. */ while (lkm_v & LKM_ALLOC) { if (flag & FNONBLOCK) /* don't hang */ return (EBUSY); lkm_v |= LKM_WANT; /* * Sleep pending unlock; we use tsleep() to allow * an alarm out of the open. */ error = tsleep((caddr_t)&lkm_v, TTIPRI|PCATCH, "lkmopn", 0); if (error) return (error); /* leave LKM_WANT set -- no problem */ } lkm_v |= LKM_ALLOC; if (nlkms == 0) lkminit(); /* XXX */ return (0); /* pseudo-device open */ } /* * Alocates new LKM table entry, fills module id, inserts in the list. * Returns NULL on failure. * */ static struct lkm_table * lkmalloc() { struct lkm_table *ret = NULL; MALLOC(ret, struct lkm_table *, sizeof(*ret), M_DEVBUF, M_WAITOK); if (ret != NULL) { ret->refcnt = ret->depcnt = 0; ret->id = nlkms++; ret->sym_id = -1; TAILQ_INSERT_TAIL(&lkmods, ret, list); } return ret; } /* * Frees the slot, decreases the number of modules. */ static void lkmfree(p) struct lkm_table *p; { #ifdef PARANOIA if (p == NULL) panic("lkmfree: freeing NULL"); #endif TAILQ_REMOVE(&lkmods, p, list); free(p, M_DEVBUF); nlkms--; } struct lkm_table * lkm_list(p) struct lkm_table *p; { if (p == NULL) p = lkmods.tqh_first; else p = p->list.tqe_next; return p; } static struct lkm_table * lkmlookup(i, name, error) int i; char *name; int *error; { register struct lkm_table *p = NULL; char istr[MAXLKMNAME]; if (i < 0) { /* unload by name */ /* * Copy name and lookup id from all loaded * modules. May fail. */ *error = copyinstr(name, istr, MAXLKMNAME-1, NULL); if (*error) return NULL; istr[MAXLKMNAME-1] = '\0'; for (p = lkmods.tqh_first; p != NULL; p = p->list.tqe_next) if (!strcmp(istr, p->private.lkm_any->lkm_name)) break; } else if (i >= nlkms) { *error = EINVAL; return NULL; } else for (p = lkmods.tqh_first; p != NULL && i--; p = p->list.tqe_next) ; if (p == NULL) *error = ENOENT; return p; } /* * Unreserve the memory associated with the current loaded module; done on * a coerced close of the lkm device (close on premature exit of modload) * or explicitly by modload as a result of a link failure. */ static void lkmunreserve() { if (lkm_state == LKMS_IDLE) return; #ifdef DDB if (curp && curp->private.lkm_any && curp->private.lkm_any->lkm_name && curp->sym_id != -1) db_del_symbol_table(curp->private.lkm_any->lkm_name); #endif /* * Actually unreserve the memory */ if (curp && curp->area) { #if defined(UVM) uvm_km_free(kmem_map, curp->area, curp->size); #else kmem_free(kmem_map, curp->area, curp->size);/**/ #endif curp->area = 0; } lkm_state = LKMS_IDLE; } int lkmclose(dev, flag, mode, p) dev_t dev; int flag; int mode; struct proc *p; { if (!(lkm_v & LKM_ALLOC)) { #ifdef LKM_DEBUG printf("LKM: close before open!\n"); #endif /* LKM_DEBUG */ return (EBADF); } /* do this before waking the herd... */ if (curp != NULL) { /* * If we close before setting used, we have aborted * by way of error or by way of close-on-exit from * a premature exit of "modload". */ lkmunreserve(); /* coerce state to LKM_IDLE */ } lkm_v &= ~LKM_ALLOC; wakeup((caddr_t)&lkm_v); /* thundering herd "problem" here */ return (0); /* pseudo-device closed */ } /*ARGSUSED*/ int lkmioctl(dev, cmd, data, flag, p) dev_t dev; u_long cmd; caddr_t data; int flag; struct proc *p; { int error = 0, i; struct lmc_resrv *resrvp; struct lmc_loadbuf *loadbufp; struct lmc_unload *unloadp; struct lmc_stat *statp; switch(cmd) { case LMRESERV: /* reserve pages for a module */ case LMRESERV_O: /* reserve pages for a module */ if (securelevel > 0) return EPERM; if ((flag & FWRITE) == 0) /* only allow this if writing */ return EPERM; resrvp = (struct lmc_resrv *)data; if ((curp = lkmalloc()) == NULL) { error = ENOMEM; /* no slots available */ break; } curp->ver = (cmd == LMRESERV) ? LKM_VERSION : LKM_OLDVERSION; resrvp->slot = curp->id; /* return slot */ /* * Get memory for module */ curp->size = resrvp->size; #if defined(UVM) curp->area = uvm_km_zalloc(kmem_map, curp->size); #else curp->area = kmem_alloc(kmem_map, curp->size);/**/ #endif curp->offset = 0; /* load offset */ resrvp->addr = curp->area; /* ret kernel addr */ if (cmd == LMRESERV && resrvp->sym_size) { curp->sym_size = resrvp->sym_size; curp->sym_symsize = resrvp->sym_symsize; #if defined(UVM) curp->syms = (caddr_t)uvm_km_zalloc(kmem_map, curp->sym_size); #else curp->syms = (caddr_t)kmem_alloc(kmem_map, curp->sym_size); #endif curp->sym_offset = 0; resrvp->sym_addr = curp->syms; /* ret symbol addr */ } else { curp->sym_size = 0; curp->syms = 0; curp->sym_offset = 0; if (cmd == LMRESERV) resrvp->sym_addr = 0; } #ifdef LKM_DEBUG printf("LKM: LMRESERV (actual = 0x%08lx)\n", curp->area); printf("LKM: LMRESERV (syms = 0x%08x)\n", curp->syms); printf("LKM: LMRESERV (adjusted = 0x%08lx)\n", trunc_page(curp->area)); #endif /* LKM_DEBUG */ lkm_state = LKMS_RESERVED; break; case LMLOADBUF: /* Copy in; stateful, follows LMRESERV */ if (securelevel > 0) return EPERM; if ((flag & FWRITE) == 0) /* only allow this if writing */ return EPERM; loadbufp = (struct lmc_loadbuf *)data; if ((lkm_state != LKMS_RESERVED && lkm_state != LKMS_LOADING) || loadbufp->cnt < 0 || loadbufp->cnt > MODIOBUF || loadbufp->cnt > curp->size - curp->offset) { error = ENOMEM; break; } /* copy in buffer full of data */ error = copyin(loadbufp->data, (caddr_t)curp->area + curp->offset, loadbufp->cnt); if (error) break; if ((curp->offset + loadbufp->cnt) < curp->size) { lkm_state = LKMS_LOADING; #ifdef LKM_DEBUG printf("LKM: LMLOADBUF (loading @ %ld of %ld, i = %d)\n", curp->offset, curp->size, loadbufp->cnt); #endif /* LKM_DEBUG */ } else { lkm_state = LKMS_LOADING_SYMS; #ifdef LKM_DEBUG printf("LKM: LMLOADBUF (loaded)\n"); #endif /* LKM_DEBUG */ } curp->offset += loadbufp->cnt; break; case LMLOADSYMS: /* Copy in; stateful, follows LMRESERV*/ if ((flag & FWRITE) == 0) /* only allow this if writing */ return EPERM; loadbufp = (struct lmc_loadbuf *)data; i = loadbufp->cnt; if ((lkm_state != LKMS_LOADING && lkm_state != LKMS_LOADING_SYMS) || i < 0 || i > MODIOBUF || i > curp->sym_size - curp->sym_offset) { error = ENOMEM; break; } /* copy in buffer full of data*/ error = copyin(loadbufp->data, curp->syms + curp->sym_offset, i); if (error) break; if ((curp->sym_offset + i) < curp->sym_size) { lkm_state = LKMS_LOADING_SYMS; #ifdef LKM_DEBUG printf( "LKM: LMLOADSYMS (loading @ %d of %d, i = %d)\n", curp->sym_offset, curp->sym_size, i); #endif /* LKM_DEBUG*/ } else { lkm_state = LKMS_LOADED; #ifdef LKM_DEBUG printf( "LKM: LMLOADSYMS (loaded)\n"); #endif /* LKM_DEBUG*/ } curp->sym_offset += i; break; case LMUNRESRV: /* discard reserved pages for a module */ if (securelevel > 0) return EPERM; if ((flag & FWRITE) == 0) /* only allow this if writing */ return EPERM; lkmunreserve(); /* coerce state to LKM_IDLE */ #ifdef LKM_DEBUG printf("LKM: LMUNRESERV\n"); #endif /* LKM_DEBUG */ break; case LMREADY: /* module loaded: call entry */ if (securelevel > 0) return EPERM; if ((flag & FWRITE) == 0) /* only allow this if writing */ return EPERM; switch (lkm_state) { case LKMS_LOADED: break; case LKMS_LOADING: case LKMS_LOADING_SYMS: if (curp->size - curp->offset > 0) /* The remainder must be bss, so we clear it */ bzero((caddr_t)curp->area + curp->offset, curp->size - curp->offset); break; default: #ifdef LKM_DEBUG printf("lkm_state is %02x\n", lkm_state); #endif /* LKM_DEBUG */ return ENXIO; } curp->entry = (int (*) __P((struct lkm_table *, int, int))) (*((long *) (data))); #ifdef LKM_DEBUG printf("LKM: call entrypoint %x\n", curp->entry); #endif /* LKM_DEBUG */ /* call entry(load)... (assigns "private" portion) */ error = (*(curp->entry))(curp, LKM_E_LOAD, curp->ver); if (error) { /* * Module may refuse loading or may have a * version mismatch... */ lkm_state = LKMS_UNLOADING; /* for lkmunreserve */ lkmunreserve(); /* free memory */ lkmfree(curp); /* free slot */ break; } #ifdef LKM_DEBUG printf("LKM: LMREADY, id=%d, dev=%d\n", curp->id, curp->private.lkm_any->lkm_offset); #endif /* LKM_DEBUG */ #ifdef DDB if (curp->syms && curp->sym_offset >= curp->sym_size) { curp->sym_id = db_add_symbol_table(curp->syms, curp->syms + curp->sym_symsize, curp->private.lkm_any->lkm_name, curp->syms, curp->syms + curp->sym_size); printf("DDB symbols added: %ld bytes\n", curp->sym_symsize); } #endif /* DDB */ curp->refcnt++; lkm_state = LKMS_IDLE; break; case LMUNLOAD: /* unload a module */ if (securelevel > 0) return EPERM; if ((flag & FWRITE) == 0) /* only allow this if writing */ return EPERM; unloadp = (struct lmc_unload *)data; if ((curp = lkmlookup(unloadp->id, unloadp->name, &error)) == NULL) break; /* error set in lkmlookup */ /* call entry(unload) */ if ((*(curp->entry))(curp, LKM_E_UNLOAD, curp->ver)) { error = EBUSY; break; } lkm_state = LKMS_UNLOADING; /* non-idle for lkmunreserve */ lkmunreserve(); /* free memory */ lkmfree(curp); /* free slot */ break; case LMSTAT: /* stat a module by id/name */ /* allow readers and writers to stat */ statp = (struct lmc_stat *)data; if ((curp = lkmlookup(statp->id, statp->name, &error)) == NULL) break; /* error set in lkmlookup */ /* * Copy out stat information for this module... */ statp->id = curp->id; statp->offset = curp->private.lkm_any->lkm_offset; statp->type = curp->private.lkm_any->lkm_type; statp->area = curp->area; statp->size = curp->size / CLBYTES; statp->private = (unsigned long)curp->private.lkm_any; statp->ver = curp->private.lkm_any->lkm_ver; copyoutstr(curp->private.lkm_any->lkm_name, statp->name, MAXLKMNAME, NULL); break; default: /* bad ioctl()... */ error = ENOTTY; break; } return (error); } /* * Acts like "nosys" but can be identified in sysent for dynamic call * number assignment for a limited number of calls. * * Place holder for system call slots reserved for loadable modules. */ int sys_lkmnosys(p, v, retval) struct proc *p; void *v; register_t *retval; { return (sys_nosys(p, v, retval)); } /* * Acts like "enodev", but can be identified in cdevsw and bdevsw for * dynamic driver major number assignment for a limited number of * drivers. * * Place holder for device switch slots reserved for loadable modules. */ int lkmenodev() { return (enodev()); } /* * A placeholder function for load/unload/stat calls; simply returns zero. * Used where people don't wnat tp specify a special function. */ int lkm_nofunc(lkmtp, cmd) struct lkm_table *lkmtp; int cmd; { return (0); } int lkmexists(lkmtp) struct lkm_table *lkmtp; { register struct lkm_table *p; /* * see if name exists... */ for (p = lkmods.tqh_first; p != NULL ; p = p->list.tqe_next) if (!strcmp(lkmtp->private.lkm_any->lkm_name, p->private.lkm_any->lkm_name) && p->refcnt) return (1); /* already loaded... */ return (0); /* module not loaded... */ } /* * For the loadable system call described by the structure pointed to * by lkmtp, load/unload/stat it depending on the cmd requested. */ static int _lkm_syscall(lkmtp, cmd) struct lkm_table *lkmtp; int cmd; { struct lkm_syscall *args = lkmtp->private.lkm_syscall; int i; int error = 0; switch(cmd) { case LKM_E_LOAD: /* don't load twice! */ if (lkmexists(lkmtp)) return (EEXIST); if ((i = args->lkm_offset) == -1) { /* auto */ /* * Search the table looking for a slot... */ for (i = 0; i < SYS_MAXSYSCALL; i++) if (sysent[i].sy_call == sys_lkmnosys) break; /* found it! */ /* out of allocable slots? */ if (i == SYS_MAXSYSCALL) { error = ENFILE; break; } } else { /* assign */ if (i < 0 || i >= SYS_MAXSYSCALL) { error = EINVAL; break; } } /* save old */ bcopy(&sysent[i], &args->lkm_oldent, sizeof(struct sysent)); /* replace with new */ bcopy(args->lkm_sysent, &sysent[i], sizeof(struct sysent)); /* done! */ args->lkm_offset = i; /* slot in sysent[] */ break; case LKM_E_UNLOAD: /* current slot... */ i = args->lkm_offset; /* replace current slot contents with old contents */ bcopy(&args->lkm_oldent, &sysent[i], sizeof(struct sysent)); break; case LKM_E_STAT: /* no special handling... */ break; } return (error); } /* * For the loadable virtual file system described by the structure pointed * to by lkmtp, load/unload/stat it depending on the cmd requested. */ static int _lkm_vfs(lkmtp, cmd) struct lkm_table *lkmtp; int cmd; { int error = 0; struct vfsconf *vfs = lkmtp->private.lkm_vfs->lkm_vfsconf; switch(cmd) { case LKM_E_LOAD: /* don't load twice! */ if (lkmexists(lkmtp)) return (EEXIST); error = vfs_register(vfs); break; case LKM_E_UNLOAD: error = vfs_unregister(vfs); break; case LKM_E_STAT: /* no special handling... */ break; } return (error); } /* * For the loadable device driver described by the structure pointed to * by lkmtp, load/unload/stat it depending on the cmd requested. */ static int _lkm_dev(lkmtp, cmd) struct lkm_table *lkmtp; int cmd; { struct lkm_dev *args = lkmtp->private.lkm_dev; int i; int error = 0; extern int nblkdev, nchrdev; /* from conf.c */ switch(cmd) { case LKM_E_LOAD: /* don't load twice! */ if (lkmexists(lkmtp)) return (EEXIST); switch(args->lkm_devtype) { case LM_DT_BLOCK: if ((i = args->lkm_offset) == -1) { /* auto */ /* * Search the table looking for a slot... */ for (i = 0; i < nblkdev; i++) if (bdevsw[i].d_open == (dev_type_open((*))) lkmenodev) break; /* found it! */ /* out of allocable slots? */ if (i == nblkdev) { error = ENFILE; break; } } else { /* assign */ if (i < 0 || i >= nblkdev) { error = EINVAL; break; } } /* save old */ bcopy(&bdevsw[i], &args->lkm_olddev.bdev, sizeof(struct bdevsw)); /* replace with new */ bcopy(args->lkm_dev.bdev, &bdevsw[i], sizeof(struct bdevsw)); /* done! */ args->lkm_offset = i; /* slot in bdevsw[] */ break; case LM_DT_CHAR: if ((i = args->lkm_offset) == -1) { /* auto */ /* * Search the table looking for a slot... */ for (i = 0; i < nchrdev; i++) if (cdevsw[i].d_open == (dev_type_open((*))) lkmenodev) break; /* found it! */ /* out of allocable slots? */ if (i == nchrdev) { error = ENFILE; break; } } else { /* assign */ if (i < 0 || i >= nchrdev) { error = EINVAL; break; } } /* save old */ bcopy(&cdevsw[i], &args->lkm_olddev.cdev, sizeof(struct cdevsw)); /* replace with new */ bcopy(args->lkm_dev.cdev, &cdevsw[i], sizeof(struct cdevsw)); /* done! */ args->lkm_offset = i; /* slot in cdevsw[] */ break; default: error = ENODEV; break; } break; case LKM_E_UNLOAD: /* current slot... */ i = args->lkm_offset; switch(args->lkm_devtype) { case LM_DT_BLOCK: /* replace current slot contents with old contents */ bcopy(&args->lkm_olddev.bdev, &bdevsw[i], sizeof(struct bdevsw)); break; case LM_DT_CHAR: /* replace current slot contents with old contents */ bcopy(&args->lkm_olddev.cdev, &cdevsw[i], sizeof(struct cdevsw)); break; default: error = ENODEV; break; } break; case LKM_E_STAT: /* no special handling... */ break; } return (error); } #ifdef STREAMS /* * For the loadable streams module described by the structure pointed to * by lkmtp, load/unload/stat it depending on the cmd requested. */ static int _lkm_strmod(lkmtp, cmd) struct lkm_table *lkmtp; int cmd; { struct lkm_strmod *args = lkmtp->private.lkm_strmod; int i; int error = 0; switch(cmd) { case LKM_E_LOAD: /* don't load twice! */ if (lkmexists(lkmtp)) return (EEXIST); break; case LKM_E_UNLOAD: break; case LKM_E_STAT: /* no special handling... */ break; } return (error); } #endif /* STREAMS */ /* * For the loadable execution class described by the structure pointed to * by lkmtp, load/unload/stat it depending on the cmd requested. */ static int _lkm_exec(lkmtp, cmd) struct lkm_table *lkmtp; int cmd; { struct lkm_exec *args = lkmtp->private.lkm_exec; int i; int error = 0; switch(cmd) { case LKM_E_LOAD: /* don't load twice! */ if (lkmexists(lkmtp)) return (EEXIST); if ((i = args->lkm_offset) == -1) { /* auto */ /* * Search the table looking for a slot... */ for (i = 0; i < nexecs; i++) if (execsw[i].es_check == NULL) break; /* found it! */ /* out of allocable slots? */ if (i == nexecs) { error = ENFILE; break; } } else { /* assign */ if (i < 0 || i >= nexecs) { error = EINVAL; break; } } /* save old */ bcopy(&execsw[i], &args->lkm_oldexec, sizeof(struct execsw)); /* replace with new */ bcopy(args->lkm_exec, &execsw[i], sizeof(struct execsw)); /* realize need to recompute max header size */ exec_maxhdrsz = 0; /* done! */ args->lkm_offset = i; /* slot in execsw[] */ break; case LKM_E_UNLOAD: /* current slot... */ i = args->lkm_offset; /* replace current slot contents with old contents */ bcopy(&args->lkm_oldexec, &execsw[i], sizeof(struct execsw)); /* realize need to recompute max header size */ exec_maxhdrsz = 0; break; case LKM_E_STAT: /* no special handling... */ break; } return (error); } /* * This code handles the per-module type "wiring-in" of loadable modules * into existing kernel tables. For "LM_MISC" modules, wiring and unwiring * is assumed to be done in their entry routines internal to the module * itself. */ int lkmdispatch(lkmtp, cmd) struct lkm_table *lkmtp; int cmd; { int error = 0; /* default = success */ #ifdef LKM_DEBUG printf("lkmdispatch: %x %d\n", lkmtp, cmd); #endif /* LKM_DEBUG */ switch(lkmtp->private.lkm_any->lkm_type) { case LM_SYSCALL: error = _lkm_syscall(lkmtp, cmd); break; case LM_VFS: error = _lkm_vfs(lkmtp, cmd); break; case LM_DEV: error = _lkm_dev(lkmtp, cmd); break; #ifdef STREAMS case LM_STRMOD: { struct lkm_strmod *args = lkmtp->private.lkm_strmod; } break; #endif /* STREAMS */ case LM_EXEC: error = _lkm_exec(lkmtp, cmd); break; case LM_MISC: /* ignore content -- no "misc-specific" procedure */ break; default: error = ENXIO; /* unknown type */ break; } return (error); }