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 1.23 2007/05/09 00:53:34 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 #include <sys/sysref2.h> 50 51 #include <vfs/devfs/devfs.h> 52 53 54 static void cdev_terminate(struct cdev *dev); 55 56 MALLOC_DEFINE(M_DEVT, "cdev_t", "dev_t storage"); 57 58 /* 59 * SYSREF Integration - reference counting, allocation, 60 * sysid and syslink integration. 61 */ 62 static struct sysref_class cdev_sysref_class = { 63 .name = "cdev", 64 .mtype = M_DEVT, 65 .proto = SYSREF_PROTO_DEV, 66 .offset = offsetof(struct cdev, si_sysref), 67 .objsize = sizeof(struct cdev), 68 .mag_capacity = 32, 69 .flags = 0, 70 .ops = { 71 .terminate = (sysref_terminate_func_t)cdev_terminate 72 } 73 }; 74 75 /* 76 * This is the number of hash-buckets. Experiements with 'real-life' 77 * udev_t's show that a prime halfway between two powers of two works 78 * best. 79 */ 80 #define DEVT_HASH 128 /* must be power of 2 */ 81 static LIST_HEAD(, cdev) dev_hash[DEVT_HASH]; 82 83 static int free_devt; 84 SYSCTL_INT(_debug, OID_AUTO, free_devt, CTLFLAG_RW, &free_devt, 0, ""); 85 int dev_ref_debug = 0; 86 SYSCTL_INT(_debug, OID_AUTO, dev_refs, CTLFLAG_RW, &dev_ref_debug, 0, ""); 87 88 /* 89 * cdev_t and u_dev_t primitives. Note that the major number is always 90 * extracted from si_umajor, not from si_devsw, because si_devsw is replaced 91 * when a device is destroyed. 92 */ 93 int 94 major(cdev_t dev) 95 { 96 if (dev == NULL) 97 return NOUDEV; 98 return(dev->si_umajor); 99 } 100 101 int 102 minor(cdev_t dev) 103 { 104 if (dev == NULL) 105 return NOUDEV; 106 return(dev->si_uminor); 107 } 108 109 /* 110 * Compatibility function with old udev_t format to convert the 111 * non-consecutive minor space into a consecutive minor space. 112 */ 113 int 114 lminor(cdev_t dev) 115 { 116 int y; 117 118 if (dev == NULL) 119 return NOUDEV; 120 y = dev->si_uminor; 121 if (y & 0x0000ff00) 122 return NOUDEV; 123 return ((y & 0xff) | (y >> 8)); 124 } 125 126 /* 127 * This is a bit complex because devices are always created relative to 128 * a particular cdevsw, including 'hidden' cdevsw's (such as the raw device 129 * backing a disk subsystem overlay), so we have to compare both the 130 * devsw and udev fields to locate the correct device. 131 * 132 * The device is created if it does not already exist. If SI_ADHOC is not 133 * set the device will be referenced (once) and SI_ADHOC will be set. 134 * The caller must explicitly add additional references to the device if 135 * the caller wishes to track additional references. 136 * 137 * NOTE: The passed ops vector must normally match the device. This is 138 * because the kernel may create shadow devices that are INVISIBLE TO 139 * USERLAND. For example, the block device backing a disk is created 140 * as a shadow underneath the user-visible disklabel management device. 141 * Sometimes a device ops vector can be overridden, such as by /dev/console. 142 * In this case and this case only we allow a match when the ops vector 143 * otherwise would not match. 144 */ 145 static 146 int 147 __devthash(int x, int y) 148 { 149 return(((x << 2) ^ y) & (DEVT_HASH - 1)); 150 } 151 152 static 153 cdev_t 154 hashdev(struct dev_ops *ops, int x, int y, int allow_intercept) 155 { 156 struct cdev *si; 157 int hash; 158 159 hash = __devthash(x, y); 160 LIST_FOREACH(si, &dev_hash[hash], si_hash) { 161 if (si->si_umajor == x && si->si_uminor == y) { 162 if (si->si_ops == ops) 163 return (si); 164 if (allow_intercept && (si->si_flags & SI_INTERCEPTED)) 165 return (si); 166 } 167 } 168 si = sysref_alloc(&cdev_sysref_class); 169 si->si_ops = ops; 170 si->si_flags |= SI_HASHED | SI_ADHOC; 171 si->si_umajor = x; 172 si->si_uminor = y; 173 si->si_inode = 0; 174 LIST_INSERT_HEAD(&dev_hash[hash], si, si_hash); 175 sysref_activate(&si->si_sysref); 176 177 dev_dclone(si); 178 if (ops != &dead_dev_ops) 179 ++ops->head.refs; 180 if (dev_ref_debug) { 181 kprintf("create dev %p %s(minor=%08x) refs=%d\n", 182 si, devtoname(si), y, 183 si->si_sysref.refcnt); 184 } 185 return (si); 186 } 187 188 /* 189 * Convert a device pointer to an old style device number. Return NOUDEV 190 * if the device is invalid or if the device (maj,min) cannot be converted 191 * to an old style udev_t. 192 */ 193 udev_t 194 dev2udev(cdev_t dev) 195 { 196 if (dev == NULL) 197 return NOUDEV; 198 199 return (udev_t)dev->si_inode; 200 } 201 202 /* 203 * Convert a device number to a device pointer. The device is referenced 204 * ad-hoc, meaning that the caller should call reference_dev() if it wishes 205 * to keep ahold of the returned structure long term. 206 * 207 * The returned device is associated with the currently installed cdevsw 208 * for the requested major number. NULL is returned if the major number 209 * has not been registered. 210 */ 211 cdev_t 212 udev2dev(udev_t x, int b) 213 { 214 if (x == NOUDEV || b != 0) 215 return(NULL); 216 217 return devfs_find_device_by_udev(x); 218 } 219 220 int 221 dev_is_good(cdev_t dev) 222 { 223 if (dev != NULL && dev->si_ops != &dead_dev_ops) 224 return(1); 225 return(0); 226 } 227 228 /* 229 * Various user device number extraction and conversion routines 230 */ 231 int 232 uminor(udev_t dev) 233 { 234 if (dev == NOUDEV) 235 return(-1); 236 return(dev & 0xffff00ff); 237 } 238 239 int 240 umajor(udev_t dev) 241 { 242 if (dev == NOUDEV) 243 return(-1); 244 return((dev & 0xff00) >> 8); 245 } 246 247 udev_t 248 makeudev(int x, int y) 249 { 250 if ((x & 0xffffff00) || (y & 0x0000ff00)) 251 return NOUDEV; 252 return ((x << 8) | y); 253 } 254 255 /* 256 * Create an internal or external device. 257 * 258 * Device majors can be overloaded and used directly by the kernel without 259 * conflict, but userland will only see the particular device major that 260 * has been installed with dev_ops_add(). 261 * 262 * This routine creates and returns an unreferenced ad-hoc entry for the 263 * device which will remain intact until the device is destroyed. If the 264 * caller intends to store the device pointer it must call reference_dev() 265 * to retain a real reference to the device. 266 * 267 * If an entry already exists, this function will set (or override) 268 * its cred requirements and name (XXX DEVFS interface). 269 */ 270 cdev_t 271 make_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid, 272 int perms, const char *fmt, ...) 273 { 274 cdev_t devfs_dev; 275 __va_list ap; 276 int i; 277 char dev_name[PATH_MAX+1]; 278 279 /* 280 * compile the cdevsw and install the device 281 */ 282 compile_dev_ops(ops); 283 284 /* 285 * Set additional fields (XXX DEVFS interface goes here) 286 */ 287 __va_start(ap, fmt); 288 i = kvcprintf(fmt, NULL, dev_name, 32, ap); 289 dev_name[i] = '\0'; 290 __va_end(ap); 291 292 /* 293 if ((devfs_dev = devfs_find_device_by_name(dev_name)) != NULL) { 294 kprintf("make_dev: Device %s already exists, returning old dev without creating new node\n", dev_name); 295 return devfs_dev; 296 } 297 */ 298 299 devfs_dev = devfs_new_cdev(ops, minor); 300 memcpy(devfs_dev->si_name, dev_name, i+1); 301 302 devfs_debug(DEVFS_DEBUG_INFO, "make_dev called for %s\n", devfs_dev->si_name); 303 devfs_create_dev(devfs_dev, uid, gid, perms); 304 305 return (devfs_dev); 306 } 307 308 309 cdev_t 310 make_only_devfs_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid, 311 int perms, const char *fmt, ...) 312 { 313 cdev_t devfs_dev; 314 __va_list ap; 315 int i; 316 //char *dev_name; 317 318 /* 319 * compile the cdevsw and install the device 320 */ 321 compile_dev_ops(ops); 322 devfs_dev = devfs_new_cdev(ops, minor); 323 324 /* 325 * Set additional fields (XXX DEVFS interface goes here) 326 */ 327 __va_start(ap, fmt); 328 i = kvcprintf(fmt, NULL, devfs_dev->si_name, 32, ap); 329 devfs_dev->si_name[i] = '\0'; 330 __va_end(ap); 331 332 333 devfs_create_dev(devfs_dev, uid, gid, perms); 334 335 return (devfs_dev); 336 } 337 338 339 cdev_t 340 make_only_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid, 341 int perms, const char *fmt, ...) 342 { 343 cdev_t devfs_dev; 344 __va_list ap; 345 int i; 346 //char *dev_name; 347 348 /* 349 * compile the cdevsw and install the device 350 */ 351 compile_dev_ops(ops); 352 devfs_dev = devfs_new_cdev(ops, minor); 353 devfs_dev->si_perms = perms; 354 devfs_dev->si_uid = uid; 355 devfs_dev->si_gid = gid; 356 357 /* 358 * Set additional fields (XXX DEVFS interface goes here) 359 */ 360 __va_start(ap, fmt); 361 i = kvcprintf(fmt, NULL, devfs_dev->si_name, 32, ap); 362 devfs_dev->si_name[i] = '\0'; 363 __va_end(ap); 364 365 reference_dev(devfs_dev); 366 367 return (devfs_dev); 368 } 369 370 void 371 destroy_only_dev(cdev_t dev) 372 { 373 devfs_destroy_cdev(dev); 374 } 375 376 377 /* 378 * This function is similar to make_dev() but no cred information or name 379 * need be specified. 380 */ 381 cdev_t 382 make_adhoc_dev(struct dev_ops *ops, int minor) 383 { 384 cdev_t dev; 385 386 dev = hashdev(ops, ops->head.maj, minor, FALSE); 387 return(dev); 388 } 389 390 /* 391 * This function is similar to make_dev() except the new device is created 392 * using an old device as a template. 393 */ 394 cdev_t 395 make_sub_dev(cdev_t odev, int minor) 396 { 397 cdev_t dev; 398 399 dev = hashdev(odev->si_ops, odev->si_umajor, minor, FALSE); 400 401 /* 402 * Copy cred requirements and name info XXX DEVFS. 403 */ 404 if (dev->si_name[0] == 0 && odev->si_name[0]) 405 bcopy(odev->si_name, dev->si_name, sizeof(dev->si_name)); 406 return (dev); 407 } 408 409 cdev_t 410 get_dev(int x, int y) 411 { 412 cdev_t dev; 413 struct dev_ops *ops; 414 415 if (x == NOUDEV) 416 return(NULL); 417 ops = dev_ops_get(x, y); 418 if (ops == NULL) 419 return(NULL); 420 dev = hashdev(ops, x, y, TRUE); 421 return(dev); 422 } 423 424 /* 425 * destroy_dev() removes the adhoc association for a device and revectors 426 * its ops to &dead_dev_ops. 427 * 428 * This routine releases the reference count associated with the ADHOC 429 * entry, plus releases the reference count held by the caller. What this 430 * means is that you should not call destroy_dev(make_dev(...)), because 431 * make_dev() does not bump the reference count (beyond what it needs to 432 * create the ad-hoc association). Any procedure that intends to destroy 433 * a device must have its own reference to it first. 434 */ 435 void 436 destroy_dev(cdev_t dev) 437 { 438 int hash; 439 440 if (dev == NULL) 441 return; 442 443 devfs_debug(DEVFS_DEBUG_DEBUG, "destroy_dev called for %s\n", dev->si_name); 444 devfs_destroy_dev(dev); 445 446 return; 447 448 if ((dev->si_flags & SI_ADHOC) == 0) { 449 release_dev(dev); 450 return; 451 } 452 if (dev_ref_debug) { 453 kprintf("destroy dev %p %s(minor=%08x) refs=%d\n", 454 dev, devtoname(dev), dev->si_uminor, 455 dev->si_sysref.refcnt); 456 } 457 if (dev->si_sysref.refcnt < 2) { 458 kprintf("destroy_dev(): too few references on device! " 459 "%p %s(minor=%08x) refs=%d\n", 460 dev, devtoname(dev), dev->si_uminor, 461 dev->si_sysref.refcnt); 462 } 463 dev->si_flags &= ~SI_ADHOC; 464 if (dev->si_flags & SI_HASHED) { 465 hash = __devthash(dev->si_umajor, dev->si_uminor); 466 LIST_REMOVE(dev, si_hash); 467 dev->si_flags &= ~SI_HASHED; 468 } 469 470 /* 471 * We have to release the ops reference before we replace the 472 * device switch with dead_dev_ops. 473 */ 474 475 476 if (dead_dev_ops.d_strategy == NULL) 477 compile_dev_ops(&dead_dev_ops); 478 if (dev->si_ops && dev->si_ops != &dead_dev_ops) 479 dev_ops_release(dev->si_ops); 480 dev->si_drv1 = NULL; 481 dev->si_drv2 = NULL; 482 dev->si_ops = &dead_dev_ops; 483 sysref_put(&dev->si_sysref); /* release adhoc association */ 484 485 release_dev(dev); /* release callers reference */ 486 } 487 488 /* 489 * Destroy all ad-hoc device associations associated with a domain within a 490 * device switch. Only the minor numbers are included in the mask/match 491 * values. 492 * 493 * Unlike the ops functions whos link structures do not contain 494 * any major bits, this function scans through the dev list via 495 * si_umajor/si_uminor. 496 * 497 * The caller must not include any major bits in the match value. 498 */ 499 void 500 destroy_all_devs(struct dev_ops *ops, u_int mask, u_int match) 501 { 502 int i; 503 cdev_t dev; 504 cdev_t ndev; 505 506 for (i = 0; i < DEVT_HASH; ++i) { 507 ndev = LIST_FIRST(&dev_hash[i]); 508 while ((dev = ndev) != NULL) { 509 ndev = LIST_NEXT(dev, si_hash); 510 if (dev->si_ops == ops && 511 ((u_int)dev->si_uminor & mask) == match 512 ) { 513 KKASSERT(dev->si_flags & SI_ADHOC); 514 reference_dev(dev); 515 destroy_dev(dev); 516 } 517 } 518 } 519 } 520 521 522 int 523 make_dev_alias(cdev_t target, const char *fmt, ...) 524 { 525 char name[PATH_MAX + 1]; 526 __va_list ap; 527 int i; 528 529 __va_start(ap, fmt); 530 i = kvcprintf(fmt, NULL, name, 32, ap); 531 name[i] = '\0'; 532 __va_end(ap); 533 534 devfs_make_alias(name, target); 535 536 return 0; 537 } 538 539 540 /* 541 * Add a reference to a device. Callers generally add their own references 542 * when they are going to store a device node in a variable for long periods 543 * of time, to prevent a disassociation from free()ing the node. 544 * 545 * Also note that a caller that intends to call destroy_dev() must first 546 * obtain a reference on the device. The ad-hoc reference you get with 547 * make_dev() and friends is NOT sufficient to be able to call destroy_dev(). 548 */ 549 cdev_t 550 reference_dev(cdev_t dev) 551 { 552 //kprintf("reference_dev\n"); 553 554 if (dev != NULL) { 555 sysref_get(&dev->si_sysref); 556 if (dev_ref_debug) { 557 kprintf("reference dev %p %s(minor=%08x) refs=%d\n", 558 dev, devtoname(dev), dev->si_uminor, 559 dev->si_sysref.refcnt); 560 } 561 } 562 return(dev); 563 } 564 565 /* 566 * release a reference on a device. The device will be terminated when the 567 * last reference has been released. 568 * 569 * NOTE: we must use si_umajor to figure out the original major number, 570 * because si_ops could already be pointing at dead_dev_ops. 571 */ 572 void 573 release_dev(cdev_t dev) 574 { 575 //kprintf("release_dev\n"); 576 577 if (dev == NULL) 578 return; 579 sysref_put(&dev->si_sysref); 580 } 581 582 static 583 void 584 cdev_terminate(struct cdev *dev) 585 { 586 int messedup = 0; 587 588 if (dev_ref_debug) { 589 kprintf("release dev %p %s(minor=%08x) refs=%d\n", 590 dev, devtoname(dev), dev->si_uminor, 591 dev->si_sysref.refcnt); 592 } 593 if (dev->si_flags & SI_ADHOC) { 594 kprintf("Warning: illegal final release on ADHOC" 595 " device %p(%s), the device was never" 596 " destroyed!\n", 597 dev, devtoname(dev)); 598 messedup = 1; 599 } 600 if (dev->si_flags & SI_HASHED) { 601 kprintf("Warning: last release on device, no call" 602 " to destroy_dev() was made! dev %p(%s)\n", 603 dev, devtoname(dev)); 604 reference_dev(dev); 605 destroy_dev(dev); 606 messedup = 1; 607 } 608 if (SLIST_FIRST(&dev->si_hlist) != NULL) { 609 kprintf("Warning: last release on device, vnode" 610 " associations still exist! dev %p(%s)\n", 611 dev, devtoname(dev)); 612 messedup = 1; 613 } 614 if (dev->si_ops && dev->si_ops != &dead_dev_ops) { 615 dev_ops_release(dev->si_ops); 616 dev->si_ops = NULL; 617 } 618 if (messedup == 0) 619 sysref_put(&dev->si_sysref); 620 } 621 622 const char * 623 devtoname(cdev_t dev) 624 { 625 int mynor; 626 int len; 627 char *p; 628 const char *dname; 629 630 if (dev == NULL) 631 return("#nodev"); 632 if (dev->si_name[0] == '#' || dev->si_name[0] == '\0') { 633 p = dev->si_name; 634 len = sizeof(dev->si_name); 635 if ((dname = dev_dname(dev)) != NULL) 636 ksnprintf(p, len, "#%s/", dname); 637 else 638 ksnprintf(p, len, "#%d/", major(dev)); 639 len -= strlen(p); 640 p += strlen(p); 641 mynor = minor(dev); 642 if (mynor < 0 || mynor > 255) 643 ksnprintf(p, len, "%#x", (u_int)mynor); 644 else 645 ksnprintf(p, len, "%d", mynor); 646 } 647 return (dev->si_name); 648 } 649 650