1 /*- 2 * Parts Copyright (c) 1995 Terrence R. Lambert 3 * Copyright (c) 1995 Julian R. Elischer 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed by Terrence R. Lambert. 17 * 4. The name Terrence R. Lambert may not be used to endorse or promote 18 * products derived from this software without specific prior written 19 * permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY Julian R. Elischer ``AS IS'' AND ANY 22 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE TERRENCE R. LAMBERT BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * $FreeBSD: src/sys/kern/kern_conf.c,v 1.73.2.3 2003/03/10 02:18:25 imp Exp $ 34 * $DragonFly: src/sys/kern/kern_conf.c,v 1.9 2004/05/26 01:29:58 dillon Exp $ 35 */ 36 37 #include <sys/param.h> 38 #include <sys/kernel.h> 39 #include <sys/sysctl.h> 40 #include <sys/systm.h> 41 #include <sys/module.h> 42 #include <sys/malloc.h> 43 #include <sys/conf.h> 44 #include <sys/vnode.h> 45 #include <sys/queue.h> 46 #include <sys/device.h> 47 #include <machine/stdarg.h> 48 49 #define cdevsw_ALLOCSTART (NUMCDEVSW/2) 50 51 MALLOC_DEFINE(M_DEVT, "dev_t", "dev_t storage"); 52 53 /* 54 * This is the number of hash-buckets. Experiements with 'real-life' 55 * udev_t's show that a prime halfway between two powers of two works 56 * best. 57 */ 58 #define DEVT_HASH 83 59 60 /* The number of dev_t's we can create before malloc(9) kick in. */ 61 #define DEVT_STASH 50 62 63 static struct specinfo devt_stash[DEVT_STASH]; 64 static LIST_HEAD(, specinfo) dev_hash[DEVT_HASH]; 65 static LIST_HEAD(, specinfo) dev_free_list; 66 67 static int free_devt; 68 SYSCTL_INT(_debug, OID_AUTO, free_devt, CTLFLAG_RW, &free_devt, 0, ""); 69 int dev_ref_debug = 0; 70 SYSCTL_INT(_debug, OID_AUTO, dev_refs, CTLFLAG_RW, &dev_ref_debug, 0, ""); 71 72 /* 73 * dev_t and u_dev_t primitives. Note that the major number is always 74 * extracted from si_udev, not from si_devsw, because si_devsw is replaced 75 * when a device is destroyed. 76 */ 77 int 78 major(dev_t x) 79 { 80 if (x == NODEV) 81 return NOUDEV; 82 return((x->si_udev >> 8) & 0xff); 83 } 84 85 int 86 minor(dev_t x) 87 { 88 if (x == NODEV) 89 return NOUDEV; 90 return(x->si_udev & 0xffff00ff); 91 } 92 93 int 94 lminor(dev_t x) 95 { 96 int i; 97 98 if (x == NODEV) 99 return NOUDEV; 100 i = minor(x); 101 return ((i & 0xff) | (i >> 8)); 102 } 103 104 /* 105 * This is a bit complex because devices are always created relative to 106 * a particular cdevsw, including 'hidden' cdevsw's (such as the raw device 107 * backing a disk subsystem overlay), so we have to compare both the 108 * devsw and udev fields to locate the correct device. 109 * 110 * The device is created if it does not already exist. If SI_ADHOC is not 111 * set the device will be referenced (once) and SI_ADHOC will be set. 112 * The caller must explicitly add additional references to the device if 113 * the caller wishes to track additional references. 114 */ 115 static 116 dev_t 117 hashdev(struct cdevsw *devsw, int x, int y) 118 { 119 struct specinfo *si; 120 udev_t udev; 121 int hash; 122 static int stashed; 123 124 udev = makeudev(x, y); 125 hash = udev % DEVT_HASH; 126 LIST_FOREACH(si, &dev_hash[hash], si_hash) { 127 if (si->si_devsw == devsw && si->si_udev == udev) 128 return (si); 129 } 130 if (stashed >= DEVT_STASH) { 131 MALLOC(si, struct specinfo *, sizeof(*si), M_DEVT, 132 M_WAITOK|M_USE_RESERVE|M_ZERO); 133 } else if (LIST_FIRST(&dev_free_list)) { 134 si = LIST_FIRST(&dev_free_list); 135 LIST_REMOVE(si, si_hash); 136 } else { 137 si = devt_stash + stashed++; 138 si->si_flags |= SI_STASHED; 139 } 140 si->si_devsw = devsw; 141 si->si_flags |= SI_HASHED | SI_ADHOC; 142 si->si_udev = udev; 143 si->si_refs = 1; 144 LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash); 145 si->si_port = devsw->d_port; 146 devsw->d_clone(si); 147 if (devsw != &dead_cdevsw) 148 ++devsw->d_refs; 149 if (dev_ref_debug) { 150 printf("create dev %p %s(minor=%08x) refs=%d\n", 151 si, devtoname(si), uminor(si->si_udev), 152 si->si_refs); 153 } 154 return (si); 155 } 156 157 /* 158 * Convert a device pointer to a device number 159 */ 160 udev_t 161 dev2udev(dev_t x) 162 { 163 if (x == NODEV) 164 return NOUDEV; 165 return (x->si_udev); 166 } 167 168 /* 169 * Convert a device number to a device pointer. The device is referenced 170 * ad-hoc, meaning that the caller should call reference_dev() if it wishes 171 * to keep ahold of the returned structure long term. 172 * 173 * The returned device is associated with the currently installed cdevsw 174 * for the requested major number. NODEV is returned if the major number 175 * has not been registered. 176 */ 177 dev_t 178 udev2dev(udev_t x, int b) 179 { 180 dev_t dev; 181 struct cdevsw *devsw; 182 183 if (x == NOUDEV || b != 0) 184 return(NODEV); 185 devsw = cdevsw_get(umajor(x), uminor(x)); 186 if (devsw == NULL) 187 return(NODEV); 188 dev = hashdev(devsw, umajor(x), uminor(x)); 189 return(dev); 190 } 191 192 int 193 dev_is_good(dev_t dev) 194 { 195 if (dev != NODEV && dev->si_devsw != &dead_cdevsw) 196 return(1); 197 return(0); 198 } 199 200 /* 201 * Various user device number extraction and conversion routines 202 */ 203 int 204 uminor(udev_t dev) 205 { 206 return(dev & 0xffff00ff); 207 } 208 209 int 210 umajor(udev_t dev) 211 { 212 return((dev & 0xff00) >> 8); 213 } 214 215 udev_t 216 makeudev(int x, int y) 217 { 218 return ((x << 8) | y); 219 } 220 221 /* 222 * Create an internal or external device. 223 * 224 * Device majors can be overloaded and used directly by the kernel without 225 * conflict, but userland will only see the particular device major that 226 * has been installed with cdevsw_add(). 227 * 228 * This routine creates an ad-hoc entry for the device. The caller must 229 * call reference_dev() to track additional references beyond the ad-hoc 230 * entry. If an entry already exists, this function will set (or override) 231 * its cred requirements and name (XXX DEVFS interface). 232 */ 233 dev_t 234 make_dev(struct cdevsw *devsw, int minor, uid_t uid, gid_t gid, 235 int perms, const char *fmt, ...) 236 { 237 dev_t dev; 238 __va_list ap; 239 int i; 240 241 /* 242 * compile the cdevsw and install the device 243 */ 244 compile_devsw(devsw); 245 dev = hashdev(devsw, devsw->d_maj, minor); 246 247 /* 248 * Set additional fields (XXX DEVFS interface goes here) 249 */ 250 __va_start(ap, fmt); 251 i = kvprintf(fmt, NULL, dev->si_name, 32, ap); 252 dev->si_name[i] = '\0'; 253 __va_end(ap); 254 255 return (dev); 256 } 257 258 /* 259 * This function is similar to make_dev() but no cred information or name 260 * need be specified. 261 */ 262 dev_t 263 make_adhoc_dev(struct cdevsw *devsw, int minor) 264 { 265 dev_t dev; 266 267 dev = hashdev(devsw, devsw->d_maj, minor); 268 return(dev); 269 } 270 271 /* 272 * This function is similar to make_dev() except the new device is created 273 * using an old device as a template. 274 */ 275 dev_t 276 make_sub_dev(dev_t odev, int minor) 277 { 278 dev_t dev; 279 280 dev = hashdev(odev->si_devsw, umajor(odev->si_udev), minor); 281 282 /* 283 * Copy cred requirements and name info XXX DEVFS. 284 */ 285 if (dev->si_name[0] == 0 && odev->si_name[0]) 286 bcopy(odev->si_name, dev->si_name, sizeof(dev->si_name)); 287 return (dev); 288 } 289 290 /* 291 * destroy_dev() removes the adhoc association for a device and revectors 292 * its devsw to &dead_cdevsw. 293 * 294 * This routine releases the reference count associated with the ADHOC 295 * entry, plus releases the reference count held by the caller. What this 296 * means is that you should not call destroy_dev(make_dev(...)), because 297 * make_dev() does not bump the reference count (beyond what it needs to 298 * create the ad-hoc association). Any procedure that intends to destroy 299 * a device must have its own reference to it first. 300 */ 301 void 302 destroy_dev(dev_t dev) 303 { 304 int hash; 305 306 if (dev == NODEV) 307 return; 308 if ((dev->si_flags & SI_ADHOC) == 0) { 309 release_dev(dev); 310 return; 311 } 312 if (dev_ref_debug) { 313 printf("destroy dev %p %s(minor=%08x) refs=%d\n", 314 dev, devtoname(dev), uminor(dev->si_udev), 315 dev->si_refs); 316 } 317 if (dev->si_refs < 2) { 318 printf("destroy_dev(): too few references on device! " 319 "%p %s(minor=%08x) refs=%d\n", 320 dev, devtoname(dev), uminor(dev->si_udev), 321 dev->si_refs); 322 } 323 dev->si_flags &= ~SI_ADHOC; 324 if (dev->si_flags & SI_HASHED) { 325 hash = dev->si_udev % DEVT_HASH; 326 LIST_REMOVE(dev, si_hash); 327 dev->si_flags &= ~SI_HASHED; 328 } 329 if (dead_cdevsw.d_port == NULL) 330 compile_devsw(&dead_cdevsw); 331 if (dev->si_devsw && dev->si_devsw != &dead_cdevsw) 332 cdevsw_release(dev->si_devsw); 333 dev->si_drv1 = NULL; 334 dev->si_drv2 = NULL; 335 dev->si_devsw = &dead_cdevsw; 336 dev->si_port = dev->si_devsw->d_port; 337 --dev->si_refs; /* release adhoc association reference */ 338 release_dev(dev); /* release callers reference */ 339 } 340 341 /* 342 * Destroy all ad-hoc device associations associated with a domain within a 343 * device switch. 344 */ 345 void 346 destroy_all_dev(struct cdevsw *devsw, u_int mask, u_int match) 347 { 348 int i; 349 dev_t dev; 350 dev_t ndev; 351 352 for (i = 0; i < DEVT_HASH; ++i) { 353 ndev = LIST_FIRST(&dev_hash[i]); 354 while ((dev = ndev) != NULL) { 355 ndev = LIST_NEXT(dev, si_hash); 356 KKASSERT(dev->si_flags & SI_ADHOC); 357 if (dev->si_devsw == devsw && 358 (dev->si_udev & mask) == match 359 ) { 360 ++dev->si_refs; 361 destroy_dev(dev); 362 } 363 } 364 } 365 } 366 367 /* 368 * Add a reference to a device. Callers generally add their own references 369 * when they are going to store a device node in a variable for long periods 370 * of time, to prevent a disassociation from free()ing the node. 371 * 372 * Also note that a caller that intends to call destroy_dev() must first 373 * obtain a reference on the device. The ad-hoc reference you get with 374 * make_dev() and friends is NOT sufficient to be able to call destroy_dev(). 375 */ 376 dev_t 377 reference_dev(dev_t dev) 378 { 379 if (dev != NODEV) { 380 ++dev->si_refs; 381 if (dev_ref_debug) { 382 printf("reference dev %p %s(minor=%08x) refs=%d\n", 383 dev, devtoname(dev), uminor(dev->si_udev), 384 dev->si_refs); 385 } 386 } 387 return(dev); 388 } 389 390 /* 391 * release a reference on a device. The device will be freed when the last 392 * reference has been released. 393 * 394 * NOTE: we must use si_udev to figure out the original (major, minor), 395 * because si_devsw could already be pointing at dead_cdevsw. 396 */ 397 void 398 release_dev(dev_t dev) 399 { 400 if (dev == NODEV) 401 return; 402 if (free_devt) { 403 KKASSERT(dev->si_refs > 0); 404 } else { 405 if (dev->si_refs <= 0) { 406 printf("Warning: extra release of dev %p(%s)\n", 407 dev, devtoname(dev)); 408 free_devt = 0; /* prevent bad things from occuring */ 409 } 410 } 411 --dev->si_refs; 412 if (dev_ref_debug) { 413 printf("release dev %p %s(minor=%08x) refs=%d\n", 414 dev, devtoname(dev), uminor(dev->si_udev), 415 dev->si_refs); 416 } 417 if (dev->si_refs == 0) { 418 if (dev->si_flags & SI_ADHOC) { 419 printf("Warning: illegal final release on ADHOC" 420 " device %p(%s), the device was never" 421 " destroyed!\n", 422 dev, devtoname(dev)); 423 } 424 if (dev->si_flags & SI_HASHED) { 425 printf("Warning: last release on device, no call" 426 " to destroy_dev() was made! dev %p(%s)\n", 427 dev, devtoname(dev)); 428 dev->si_refs = 3; 429 destroy_dev(dev); 430 dev->si_refs = 0; 431 } 432 if (SLIST_FIRST(&dev->si_hlist) != NULL) { 433 printf("Warning: last release on device, vnode" 434 " associations still exist! dev %p(%s)\n", 435 dev, devtoname(dev)); 436 free_devt = 0; /* prevent bad things from occuring */ 437 } 438 if (dev->si_devsw && dev->si_devsw != &dead_cdevsw) { 439 cdevsw_release(dev->si_devsw); 440 dev->si_devsw = NULL; 441 } 442 if (free_devt) { 443 if (dev->si_flags & SI_STASHED) { 444 bzero(dev, sizeof(*dev)); 445 LIST_INSERT_HEAD(&dev_free_list, dev, si_hash); 446 } else { 447 FREE(dev, M_DEVT); 448 } 449 } 450 } 451 } 452 453 const char * 454 devtoname(dev_t dev) 455 { 456 int mynor; 457 int len; 458 char *p; 459 const char *dname; 460 461 if (dev == NODEV) 462 return("#nodev"); 463 if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') { 464 p = dev->si_name; 465 len = sizeof(dev->si_name); 466 if ((dname = dev_dname(dev)) != NULL) 467 snprintf(p, len, "#%s/", dname); 468 else 469 snprintf(p, len, "#%d/", major(dev)); 470 len -= strlen(p); 471 p += strlen(p); 472 mynor = minor(dev); 473 if (mynor < 0 || mynor > 255) 474 snprintf(p, len, "%#x", (u_int)mynor); 475 else 476 snprintf(p, len, "%d", mynor); 477 } 478 return (dev->si_name); 479 } 480 481