1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1997, 1998, 1999 Kenneth D. Merry. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. The name of the author may not be used to endorse or promote products 16 * derived from this software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #include <sys/cdefs.h> 32 __FBSDID("$FreeBSD$"); 33 34 #include <sys/param.h> 35 #include <sys/kernel.h> 36 #include <sys/systm.h> 37 #include <sys/bio.h> 38 #include <sys/devicestat.h> 39 #include <sys/sdt.h> 40 #include <sys/sysctl.h> 41 #include <sys/malloc.h> 42 #include <sys/lock.h> 43 #include <sys/mutex.h> 44 #include <sys/conf.h> 45 #include <vm/vm.h> 46 #include <vm/pmap.h> 47 48 #include <machine/atomic.h> 49 50 SDT_PROVIDER_DEFINE(io); 51 52 SDT_PROBE_DEFINE2(io, , , start, "struct bio *", "struct devstat *"); 53 SDT_PROBE_DEFINE2(io, , , done, "struct bio *", "struct devstat *"); 54 SDT_PROBE_DEFINE2(io, , , wait__start, "struct bio *", 55 "struct devstat *"); 56 SDT_PROBE_DEFINE2(io, , , wait__done, "struct bio *", 57 "struct devstat *"); 58 59 #define DTRACE_DEVSTAT_START() SDT_PROBE2(io, , , start, NULL, ds) 60 #define DTRACE_DEVSTAT_BIO_START() SDT_PROBE2(io, , , start, bp, ds) 61 #define DTRACE_DEVSTAT_DONE() SDT_PROBE2(io, , , done, NULL, ds) 62 #define DTRACE_DEVSTAT_BIO_DONE() SDT_PROBE2(io, , , done, bp, ds) 63 #define DTRACE_DEVSTAT_WAIT_START() SDT_PROBE2(io, , , wait__start, NULL, ds) 64 #define DTRACE_DEVSTAT_WAIT_DONE() SDT_PROBE2(io, , , wait__done, NULL, ds) 65 66 static int devstat_num_devs; 67 static long devstat_generation = 1; 68 static int devstat_version = DEVSTAT_VERSION; 69 static int devstat_current_devnumber; 70 static struct mtx devstat_mutex; 71 MTX_SYSINIT(devstat_mutex, &devstat_mutex, "devstat", MTX_DEF); 72 73 static struct devstatlist device_statq = STAILQ_HEAD_INITIALIZER(device_statq); 74 static struct devstat *devstat_alloc(void); 75 static void devstat_free(struct devstat *); 76 static void devstat_add_entry(struct devstat *ds, const void *dev_name, 77 int unit_number, uint32_t block_size, 78 devstat_support_flags flags, 79 devstat_type_flags device_type, 80 devstat_priority priority); 81 82 /* 83 * Allocate a devstat and initialize it 84 */ 85 struct devstat * 86 devstat_new_entry(const void *dev_name, 87 int unit_number, uint32_t block_size, 88 devstat_support_flags flags, 89 devstat_type_flags device_type, 90 devstat_priority priority) 91 { 92 struct devstat *ds; 93 94 mtx_assert(&devstat_mutex, MA_NOTOWNED); 95 96 ds = devstat_alloc(); 97 mtx_lock(&devstat_mutex); 98 if (unit_number == -1) { 99 ds->unit_number = unit_number; 100 ds->id = dev_name; 101 binuptime(&ds->creation_time); 102 devstat_generation++; 103 } else { 104 devstat_add_entry(ds, dev_name, unit_number, block_size, 105 flags, device_type, priority); 106 } 107 mtx_unlock(&devstat_mutex); 108 return (ds); 109 } 110 111 /* 112 * Take a malloced and zeroed devstat structure given to us, fill it in 113 * and add it to the queue of devices. 114 */ 115 static void 116 devstat_add_entry(struct devstat *ds, const void *dev_name, 117 int unit_number, uint32_t block_size, 118 devstat_support_flags flags, 119 devstat_type_flags device_type, 120 devstat_priority priority) 121 { 122 struct devstatlist *devstat_head; 123 struct devstat *ds_tmp; 124 125 mtx_assert(&devstat_mutex, MA_OWNED); 126 devstat_num_devs++; 127 128 devstat_head = &device_statq; 129 130 /* 131 * Priority sort. Each driver passes in its priority when it adds 132 * its devstat entry. Drivers are sorted first by priority, and 133 * then by probe order. 134 * 135 * For the first device, we just insert it, since the priority 136 * doesn't really matter yet. Subsequent devices are inserted into 137 * the list using the order outlined above. 138 */ 139 if (devstat_num_devs == 1) 140 STAILQ_INSERT_TAIL(devstat_head, ds, dev_links); 141 else { 142 STAILQ_FOREACH(ds_tmp, devstat_head, dev_links) { 143 struct devstat *ds_next; 144 145 ds_next = STAILQ_NEXT(ds_tmp, dev_links); 146 147 /* 148 * If we find a break between higher and lower 149 * priority items, and if this item fits in the 150 * break, insert it. This also applies if the 151 * "lower priority item" is the end of the list. 152 */ 153 if ((priority <= ds_tmp->priority) 154 && ((ds_next == NULL) 155 || (priority > ds_next->priority))) { 156 STAILQ_INSERT_AFTER(devstat_head, ds_tmp, ds, 157 dev_links); 158 break; 159 } else if (priority > ds_tmp->priority) { 160 /* 161 * If this is the case, we should be able 162 * to insert ourselves at the head of the 163 * list. If we can't, something is wrong. 164 */ 165 if (ds_tmp == STAILQ_FIRST(devstat_head)) { 166 STAILQ_INSERT_HEAD(devstat_head, 167 ds, dev_links); 168 break; 169 } else { 170 STAILQ_INSERT_TAIL(devstat_head, 171 ds, dev_links); 172 printf("devstat_add_entry: HELP! " 173 "sorting problem detected " 174 "for name %p unit %d\n", 175 dev_name, unit_number); 176 break; 177 } 178 } 179 } 180 } 181 182 ds->device_number = devstat_current_devnumber++; 183 ds->unit_number = unit_number; 184 strlcpy(ds->device_name, dev_name, DEVSTAT_NAME_LEN); 185 ds->block_size = block_size; 186 ds->flags = flags; 187 ds->device_type = device_type; 188 ds->priority = priority; 189 binuptime(&ds->creation_time); 190 devstat_generation++; 191 } 192 193 /* 194 * Remove a devstat structure from the list of devices. 195 */ 196 void 197 devstat_remove_entry(struct devstat *ds) 198 { 199 struct devstatlist *devstat_head; 200 201 mtx_assert(&devstat_mutex, MA_NOTOWNED); 202 if (ds == NULL) 203 return; 204 205 mtx_lock(&devstat_mutex); 206 207 devstat_head = &device_statq; 208 209 /* Remove this entry from the devstat queue */ 210 atomic_add_acq_int(&ds->sequence1, 1); 211 if (ds->unit_number != -1) { 212 devstat_num_devs--; 213 STAILQ_REMOVE(devstat_head, ds, devstat, dev_links); 214 } 215 devstat_free(ds); 216 devstat_generation++; 217 mtx_unlock(&devstat_mutex); 218 } 219 220 /* 221 * Record a transaction start. 222 * 223 * See comments for devstat_end_transaction(). Ordering is very important 224 * here. 225 */ 226 void 227 devstat_start_transaction(struct devstat *ds, const struct bintime *now) 228 { 229 230 mtx_assert(&devstat_mutex, MA_NOTOWNED); 231 232 /* sanity check */ 233 if (ds == NULL) 234 return; 235 236 atomic_add_acq_int(&ds->sequence1, 1); 237 /* 238 * We only want to set the start time when we are going from idle 239 * to busy. The start time is really the start of the latest busy 240 * period. 241 */ 242 if (ds->start_count == ds->end_count) { 243 if (now != NULL) 244 ds->busy_from = *now; 245 else 246 binuptime(&ds->busy_from); 247 } 248 ds->start_count++; 249 atomic_add_rel_int(&ds->sequence0, 1); 250 DTRACE_DEVSTAT_START(); 251 } 252 253 void 254 devstat_start_transaction_bio(struct devstat *ds, struct bio *bp) 255 { 256 257 mtx_assert(&devstat_mutex, MA_NOTOWNED); 258 259 /* sanity check */ 260 if (ds == NULL) 261 return; 262 263 binuptime(&bp->bio_t0); 264 devstat_start_transaction(ds, &bp->bio_t0); 265 DTRACE_DEVSTAT_BIO_START(); 266 } 267 268 /* 269 * Record the ending of a transaction, and incrment the various counters. 270 * 271 * Ordering in this function, and in devstat_start_transaction() is VERY 272 * important. The idea here is to run without locks, so we are very 273 * careful to only modify some fields on the way "down" (i.e. at 274 * transaction start) and some fields on the way "up" (i.e. at transaction 275 * completion). One exception is busy_from, which we only modify in 276 * devstat_start_transaction() when there are no outstanding transactions, 277 * and thus it can't be modified in devstat_end_transaction() 278 * simultaneously. 279 * 280 * The sequence0 and sequence1 fields are provided to enable an application 281 * spying on the structures with mmap(2) to tell when a structure is in a 282 * consistent state or not. 283 * 284 * For this to work 100% reliably, it is important that the two fields 285 * are at opposite ends of the structure and that they are incremented 286 * in the opposite order of how a memcpy(3) in userland would copy them. 287 * We assume that the copying happens front to back, but there is actually 288 * no way short of writing your own memcpy(3) replacement to guarantee 289 * this will be the case. 290 * 291 * In addition to this, being a kind of locks, they must be updated with 292 * atomic instructions using appropriate memory barriers. 293 */ 294 void 295 devstat_end_transaction(struct devstat *ds, uint32_t bytes, 296 devstat_tag_type tag_type, devstat_trans_flags flags, 297 const struct bintime *now, const struct bintime *then) 298 { 299 struct bintime dt, lnow; 300 301 /* sanity check */ 302 if (ds == NULL) 303 return; 304 305 if (now == NULL) { 306 binuptime(&lnow); 307 now = &lnow; 308 } 309 310 atomic_add_acq_int(&ds->sequence1, 1); 311 /* Update byte and operations counts */ 312 ds->bytes[flags] += bytes; 313 ds->operations[flags]++; 314 315 /* 316 * Keep a count of the various tag types sent. 317 */ 318 if ((ds->flags & DEVSTAT_NO_ORDERED_TAGS) == 0 && 319 tag_type != DEVSTAT_TAG_NONE) 320 ds->tag_types[tag_type]++; 321 322 if (then != NULL) { 323 /* Update duration of operations */ 324 dt = *now; 325 bintime_sub(&dt, then); 326 bintime_add(&ds->duration[flags], &dt); 327 } 328 329 /* Accumulate busy time */ 330 dt = *now; 331 bintime_sub(&dt, &ds->busy_from); 332 bintime_add(&ds->busy_time, &dt); 333 ds->busy_from = *now; 334 335 ds->end_count++; 336 atomic_add_rel_int(&ds->sequence0, 1); 337 DTRACE_DEVSTAT_DONE(); 338 } 339 340 void 341 devstat_end_transaction_bio(struct devstat *ds, const struct bio *bp) 342 { 343 344 devstat_end_transaction_bio_bt(ds, bp, NULL); 345 } 346 347 void 348 devstat_end_transaction_bio_bt(struct devstat *ds, const struct bio *bp, 349 const struct bintime *now) 350 { 351 devstat_trans_flags flg; 352 353 /* sanity check */ 354 if (ds == NULL) 355 return; 356 357 if (bp->bio_cmd == BIO_DELETE) 358 flg = DEVSTAT_FREE; 359 else if ((bp->bio_cmd == BIO_READ) 360 || ((bp->bio_cmd == BIO_ZONE) 361 && (bp->bio_zone.zone_cmd == DISK_ZONE_REPORT_ZONES))) 362 flg = DEVSTAT_READ; 363 else if (bp->bio_cmd == BIO_WRITE) 364 flg = DEVSTAT_WRITE; 365 else 366 flg = DEVSTAT_NO_DATA; 367 368 devstat_end_transaction(ds, bp->bio_bcount - bp->bio_resid, 369 DEVSTAT_TAG_SIMPLE, flg, now, &bp->bio_t0); 370 DTRACE_DEVSTAT_BIO_DONE(); 371 } 372 373 /* 374 * This is the sysctl handler for the devstat package. The data pushed out 375 * on the kern.devstat.all sysctl variable consists of the current devstat 376 * generation number, and then an array of devstat structures, one for each 377 * device in the system. 378 * 379 * This is more cryptic that obvious, but basically we neither can nor 380 * want to hold the devstat_mutex for any amount of time, so we grab it 381 * only when we need to and keep an eye on devstat_generation all the time. 382 */ 383 static int 384 sysctl_devstat(SYSCTL_HANDLER_ARGS) 385 { 386 int error; 387 long mygen; 388 struct devstat *nds; 389 390 mtx_assert(&devstat_mutex, MA_NOTOWNED); 391 392 /* 393 * XXX devstat_generation should really be "volatile" but that 394 * XXX freaks out the sysctl macro below. The places where we 395 * XXX change it and inspect it are bracketed in the mutex which 396 * XXX guarantees us proper write barriers. I don't believe the 397 * XXX compiler is allowed to optimize mygen away across calls 398 * XXX to other functions, so the following is belived to be safe. 399 */ 400 mygen = devstat_generation; 401 402 error = SYSCTL_OUT(req, &mygen, sizeof(mygen)); 403 404 if (devstat_num_devs == 0) 405 return(0); 406 407 if (error != 0) 408 return (error); 409 410 mtx_lock(&devstat_mutex); 411 nds = STAILQ_FIRST(&device_statq); 412 if (mygen != devstat_generation) 413 error = EBUSY; 414 mtx_unlock(&devstat_mutex); 415 416 if (error != 0) 417 return (error); 418 419 for (;nds != NULL;) { 420 error = SYSCTL_OUT(req, nds, sizeof(struct devstat)); 421 if (error != 0) 422 return (error); 423 mtx_lock(&devstat_mutex); 424 if (mygen != devstat_generation) 425 error = EBUSY; 426 else 427 nds = STAILQ_NEXT(nds, dev_links); 428 mtx_unlock(&devstat_mutex); 429 if (error != 0) 430 return (error); 431 } 432 return(error); 433 } 434 435 /* 436 * Sysctl entries for devstat. The first one is a node that all the rest 437 * hang off of. 438 */ 439 static SYSCTL_NODE(_kern, OID_AUTO, devstat, CTLFLAG_RD, NULL, 440 "Device Statistics"); 441 442 SYSCTL_PROC(_kern_devstat, OID_AUTO, all, CTLFLAG_RD|CTLTYPE_OPAQUE, 443 NULL, 0, sysctl_devstat, "S,devstat", "All devices in the devstat list"); 444 /* 445 * Export the number of devices in the system so that userland utilities 446 * can determine how much memory to allocate to hold all the devices. 447 */ 448 SYSCTL_INT(_kern_devstat, OID_AUTO, numdevs, CTLFLAG_RD, 449 &devstat_num_devs, 0, "Number of devices in the devstat list"); 450 SYSCTL_LONG(_kern_devstat, OID_AUTO, generation, CTLFLAG_RD, 451 &devstat_generation, 0, "Devstat list generation"); 452 SYSCTL_INT(_kern_devstat, OID_AUTO, version, CTLFLAG_RD, 453 &devstat_version, 0, "Devstat list version number"); 454 455 /* 456 * Allocator for struct devstat structures. We sub-allocate these from pages 457 * which we get from malloc. These pages are exported for mmap(2)'ing through 458 * a miniature device driver 459 */ 460 461 #define statsperpage (PAGE_SIZE / sizeof(struct devstat)) 462 463 static d_mmap_t devstat_mmap; 464 465 static struct cdevsw devstat_cdevsw = { 466 .d_version = D_VERSION, 467 .d_mmap = devstat_mmap, 468 .d_name = "devstat", 469 }; 470 471 struct statspage { 472 TAILQ_ENTRY(statspage) list; 473 struct devstat *stat; 474 u_int nfree; 475 }; 476 477 static TAILQ_HEAD(, statspage) pagelist = TAILQ_HEAD_INITIALIZER(pagelist); 478 static MALLOC_DEFINE(M_DEVSTAT, "devstat", "Device statistics"); 479 480 static int 481 devstat_mmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr, 482 int nprot, vm_memattr_t *memattr) 483 { 484 struct statspage *spp; 485 486 if (nprot != VM_PROT_READ) 487 return (-1); 488 mtx_lock(&devstat_mutex); 489 TAILQ_FOREACH(spp, &pagelist, list) { 490 if (offset == 0) { 491 *paddr = vtophys(spp->stat); 492 mtx_unlock(&devstat_mutex); 493 return (0); 494 } 495 offset -= PAGE_SIZE; 496 } 497 mtx_unlock(&devstat_mutex); 498 return (-1); 499 } 500 501 static struct devstat * 502 devstat_alloc(void) 503 { 504 struct devstat *dsp; 505 struct statspage *spp, *spp2; 506 u_int u; 507 static int once; 508 509 mtx_assert(&devstat_mutex, MA_NOTOWNED); 510 if (!once) { 511 make_dev_credf(MAKEDEV_ETERNAL | MAKEDEV_CHECKNAME, 512 &devstat_cdevsw, 0, NULL, UID_ROOT, GID_WHEEL, 0444, 513 DEVSTAT_DEVICE_NAME); 514 once = 1; 515 } 516 spp2 = NULL; 517 mtx_lock(&devstat_mutex); 518 for (;;) { 519 TAILQ_FOREACH(spp, &pagelist, list) { 520 if (spp->nfree > 0) 521 break; 522 } 523 if (spp != NULL) 524 break; 525 mtx_unlock(&devstat_mutex); 526 spp2 = malloc(sizeof *spp, M_DEVSTAT, M_ZERO | M_WAITOK); 527 spp2->stat = malloc(PAGE_SIZE, M_DEVSTAT, M_ZERO | M_WAITOK); 528 spp2->nfree = statsperpage; 529 530 /* 531 * If free statspages were added while the lock was released 532 * just reuse them. 533 */ 534 mtx_lock(&devstat_mutex); 535 TAILQ_FOREACH(spp, &pagelist, list) 536 if (spp->nfree > 0) 537 break; 538 if (spp == NULL) { 539 spp = spp2; 540 541 /* 542 * It would make more sense to add the new page at the 543 * head but the order on the list determine the 544 * sequence of the mapping so we can't do that. 545 */ 546 TAILQ_INSERT_TAIL(&pagelist, spp, list); 547 } else 548 break; 549 } 550 dsp = spp->stat; 551 for (u = 0; u < statsperpage; u++) { 552 if (dsp->allocated == 0) 553 break; 554 dsp++; 555 } 556 spp->nfree--; 557 dsp->allocated = 1; 558 mtx_unlock(&devstat_mutex); 559 if (spp2 != NULL && spp2 != spp) { 560 free(spp2->stat, M_DEVSTAT); 561 free(spp2, M_DEVSTAT); 562 } 563 return (dsp); 564 } 565 566 static void 567 devstat_free(struct devstat *dsp) 568 { 569 struct statspage *spp; 570 571 mtx_assert(&devstat_mutex, MA_OWNED); 572 bzero(dsp, sizeof *dsp); 573 TAILQ_FOREACH(spp, &pagelist, list) { 574 if (dsp >= spp->stat && dsp < (spp->stat + statsperpage)) { 575 spp->nfree++; 576 return; 577 } 578 } 579 } 580 581 SYSCTL_INT(_debug_sizeof, OID_AUTO, devstat, CTLFLAG_RD, 582 SYSCTL_NULL_INT_PTR, sizeof(struct devstat), "sizeof(struct devstat)"); 583