1 /*-
2 * Copyright (c) 1997, 1998, 1999 Kenneth D. Merry.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD: releng/9.2/sys/kern/subr_devstat.c 248085 2013-03-09 02:36:32Z marius $");
31
32 #include "opt_kdtrace.h"
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/sysctl.h>
40 #include <sys/malloc.h>
41 #include <sys/lock.h>
42 #include <sys/mutex.h>
43 #include <sys/conf.h>
44 #include <vm/vm.h>
45 #include <vm/pmap.h>
46
47 #include <machine/atomic.h>
48
49 #ifdef KDTRACE_HOOKS
50 #include <sys/dtrace_bsd.h>
51
52 dtrace_io_start_probe_func_t dtrace_io_start_probe;
53 dtrace_io_done_probe_func_t dtrace_io_done_probe;
54 dtrace_io_wait_start_probe_func_t dtrace_io_wait_start_probe;
55 dtrace_io_wait_done_probe_func_t dtrace_io_wait_done_probe;
56
57 uint32_t dtio_start_id;
58 uint32_t dtio_done_id;
59 uint32_t dtio_wait_start_id;
60 uint32_t dtio_wait_done_id;
61
62 #define DTRACE_DEVSTAT_START() \
63 if (dtrace_io_start_probe != NULL) \
64 (*dtrace_io_start_probe)(dtio_start_id, NULL, ds);
65
66 #define DTRACE_DEVSTAT_BIO_START() \
67 if (dtrace_io_start_probe != NULL) \
68 (*dtrace_io_start_probe)(dtio_start_id, bp, ds);
69
70 #define DTRACE_DEVSTAT_DONE() \
71 if (dtrace_io_done_probe != NULL) \
72 (*dtrace_io_done_probe)(dtio_done_id, NULL, ds);
73
74 #define DTRACE_DEVSTAT_BIO_DONE() \
75 if (dtrace_io_done_probe != NULL) \
76 (*dtrace_io_done_probe)(dtio_done_id, bp, ds);
77
78 #define DTRACE_DEVSTAT_WAIT_START() \
79 if (dtrace_io_wait_start_probe != NULL) \
80 (*dtrace_io_wait_start_probe)(dtio_wait_start_id, NULL, ds);
81
82 #define DTRACE_DEVSTAT_WAIT_DONE() \
83 if (dtrace_io_wait_done_probe != NULL) \
84 (*dtrace_io_wait_done_probe)(dtio_wait_done_id, NULL, ds);
85
86 #else /* ! KDTRACE_HOOKS */
87
88 #define DTRACE_DEVSTAT_START()
89
90 #define DTRACE_DEVSTAT_BIO_START()
91
92 #define DTRACE_DEVSTAT_DONE()
93
94 #define DTRACE_DEVSTAT_BIO_DONE()
95
96 #define DTRACE_DEVSTAT_WAIT_START()
97
98 #define DTRACE_DEVSTAT_WAIT_DONE()
99 #endif /* KDTRACE_HOOKS */
100
101 static int devstat_num_devs;
102 static long devstat_generation = 1;
103 static int devstat_version = DEVSTAT_VERSION;
104 static int devstat_current_devnumber;
105 static struct mtx devstat_mutex;
106 MTX_SYSINIT(devstat_mutex, &devstat_mutex, "devstat", MTX_DEF);
107
108 static struct devstatlist device_statq = STAILQ_HEAD_INITIALIZER(device_statq);
109 static struct devstat *devstat_alloc(void);
110 static void devstat_free(struct devstat *);
111 static void devstat_add_entry(struct devstat *ds, const void *dev_name,
112 int unit_number, uint32_t block_size,
113 devstat_support_flags flags,
114 devstat_type_flags device_type,
115 devstat_priority priority);
116
117 /*
118 * Allocate a devstat and initialize it
119 */
120 struct devstat *
121 devstat_new_entry(const void *dev_name,
122 int unit_number, uint32_t block_size,
123 devstat_support_flags flags,
124 devstat_type_flags device_type,
125 devstat_priority priority)
126 {
127 struct devstat *ds;
128
129 mtx_assert(&devstat_mutex, MA_NOTOWNED);
130
131 ds = devstat_alloc();
132 mtx_lock(&devstat_mutex);
133 if (unit_number == -1) {
134 ds->id = dev_name;
135 binuptime(&ds->creation_time);
136 devstat_generation++;
137 } else {
138 devstat_add_entry(ds, dev_name, unit_number, block_size,
139 flags, device_type, priority);
140 }
141 mtx_unlock(&devstat_mutex);
142 return (ds);
143 }
144
145 /*
146 * Take a malloced and zeroed devstat structure given to us, fill it in
147 * and add it to the queue of devices.
148 */
149 static void
150 devstat_add_entry(struct devstat *ds, const void *dev_name,
151 int unit_number, uint32_t block_size,
152 devstat_support_flags flags,
153 devstat_type_flags device_type,
154 devstat_priority priority)
155 {
156 struct devstatlist *devstat_head;
157 struct devstat *ds_tmp;
158
159 mtx_assert(&devstat_mutex, MA_OWNED);
160 devstat_num_devs++;
161
162 devstat_head = &device_statq;
163
164 /*
165 * Priority sort. Each driver passes in its priority when it adds
166 * its devstat entry. Drivers are sorted first by priority, and
167 * then by probe order.
168 *
169 * For the first device, we just insert it, since the priority
170 * doesn't really matter yet. Subsequent devices are inserted into
171 * the list using the order outlined above.
172 */
173 if (devstat_num_devs == 1)
174 STAILQ_INSERT_TAIL(devstat_head, ds, dev_links);
175 else {
176 STAILQ_FOREACH(ds_tmp, devstat_head, dev_links) {
177 struct devstat *ds_next;
178
179 ds_next = STAILQ_NEXT(ds_tmp, dev_links);
180
181 /*
182 * If we find a break between higher and lower
183 * priority items, and if this item fits in the
184 * break, insert it. This also applies if the
185 * "lower priority item" is the end of the list.
186 */
187 if ((priority <= ds_tmp->priority)
188 && ((ds_next == NULL)
189 || (priority > ds_next->priority))) {
190 STAILQ_INSERT_AFTER(devstat_head, ds_tmp, ds,
191 dev_links);
192 break;
193 } else if (priority > ds_tmp->priority) {
194 /*
195 * If this is the case, we should be able
196 * to insert ourselves at the head of the
197 * list. If we can't, something is wrong.
198 */
199 if (ds_tmp == STAILQ_FIRST(devstat_head)) {
200 STAILQ_INSERT_HEAD(devstat_head,
201 ds, dev_links);
202 break;
203 } else {
204 STAILQ_INSERT_TAIL(devstat_head,
205 ds, dev_links);
206 printf("devstat_add_entry: HELP! "
207 "sorting problem detected "
208 "for name %p unit %d\n",
209 dev_name, unit_number);
210 break;
211 }
212 }
213 }
214 }
215
216 ds->device_number = devstat_current_devnumber++;
217 ds->unit_number = unit_number;
218 strlcpy(ds->device_name, dev_name, DEVSTAT_NAME_LEN);
219 ds->block_size = block_size;
220 ds->flags = flags;
221 ds->device_type = device_type;
222 ds->priority = priority;
223 binuptime(&ds->creation_time);
224 devstat_generation++;
225 }
226
227 /*
228 * Remove a devstat structure from the list of devices.
229 */
230 void
231 devstat_remove_entry(struct devstat *ds)
232 {
233 struct devstatlist *devstat_head;
234
235 mtx_assert(&devstat_mutex, MA_NOTOWNED);
236 if (ds == NULL)
237 return;
238
239 mtx_lock(&devstat_mutex);
240
241 devstat_head = &device_statq;
242
243 /* Remove this entry from the devstat queue */
244 atomic_add_acq_int(&ds->sequence1, 1);
245 if (ds->id == NULL) {
246 devstat_num_devs--;
247 STAILQ_REMOVE(devstat_head, ds, devstat, dev_links);
248 }
249 devstat_free(ds);
250 devstat_generation++;
251 mtx_unlock(&devstat_mutex);
252 }
253
254 /*
255 * Record a transaction start.
256 *
257 * See comments for devstat_end_transaction(). Ordering is very important
258 * here.
259 */
260 void
261 devstat_start_transaction(struct devstat *ds, struct bintime *now)
262 {
263
264 mtx_assert(&devstat_mutex, MA_NOTOWNED);
265
266 /* sanity check */
267 if (ds == NULL)
268 return;
269
270 atomic_add_acq_int(&ds->sequence1, 1);
271 /*
272 * We only want to set the start time when we are going from idle
273 * to busy. The start time is really the start of the latest busy
274 * period.
275 */
276 if (ds->start_count == ds->end_count) {
277 if (now != NULL)
278 ds->busy_from = *now;
279 else
280 binuptime(&ds->busy_from);
281 }
282 ds->start_count++;
283 atomic_add_rel_int(&ds->sequence0, 1);
284 DTRACE_DEVSTAT_START();
285 }
286
287 void
288 devstat_start_transaction_bio(struct devstat *ds, struct bio *bp)
289 {
290
291 mtx_assert(&devstat_mutex, MA_NOTOWNED);
292
293 /* sanity check */
294 if (ds == NULL)
295 return;
296
297 binuptime(&bp->bio_t0);
298 devstat_start_transaction(ds, &bp->bio_t0);
299 DTRACE_DEVSTAT_BIO_START();
300 }
301
302 /*
303 * Record the ending of a transaction, and incrment the various counters.
304 *
305 * Ordering in this function, and in devstat_start_transaction() is VERY
306 * important. The idea here is to run without locks, so we are very
307 * careful to only modify some fields on the way "down" (i.e. at
308 * transaction start) and some fields on the way "up" (i.e. at transaction
309 * completion). One exception is busy_from, which we only modify in
310 * devstat_start_transaction() when there are no outstanding transactions,
311 * and thus it can't be modified in devstat_end_transaction()
312 * simultaneously.
313 *
314 * The sequence0 and sequence1 fields are provided to enable an application
315 * spying on the structures with mmap(2) to tell when a structure is in a
316 * consistent state or not.
317 *
318 * For this to work 100% reliably, it is important that the two fields
319 * are at opposite ends of the structure and that they are incremented
320 * in the opposite order of how a memcpy(3) in userland would copy them.
321 * We assume that the copying happens front to back, but there is actually
322 * no way short of writing your own memcpy(3) replacement to guarantee
323 * this will be the case.
324 *
325 * In addition to this, being a kind of locks, they must be updated with
326 * atomic instructions using appropriate memory barriers.
327 */
328 void
329 devstat_end_transaction(struct devstat *ds, uint32_t bytes,
330 devstat_tag_type tag_type, devstat_trans_flags flags,
331 struct bintime *now, struct bintime *then)
332 {
333 struct bintime dt, lnow;
334
335 /* sanity check */
336 if (ds == NULL)
337 return;
338
339 if (now == NULL) {
340 now = &lnow;
341 binuptime(now);
342 }
343
344 atomic_add_acq_int(&ds->sequence1, 1);
345 /* Update byte and operations counts */
346 ds->bytes[flags] += bytes;
347 ds->operations[flags]++;
348
349 /*
350 * Keep a count of the various tag types sent.
351 */
352 if ((ds->flags & DEVSTAT_NO_ORDERED_TAGS) == 0 &&
353 tag_type != DEVSTAT_TAG_NONE)
354 ds->tag_types[tag_type]++;
355
356 if (then != NULL) {
357 /* Update duration of operations */
358 dt = *now;
359 bintime_sub(&dt, then);
360 bintime_add(&ds->duration[flags], &dt);
361 }
362
363 /* Accumulate busy time */
364 dt = *now;
365 bintime_sub(&dt, &ds->busy_from);
366 bintime_add(&ds->busy_time, &dt);
367 ds->busy_from = *now;
368
369 ds->end_count++;
370 atomic_add_rel_int(&ds->sequence0, 1);
371 DTRACE_DEVSTAT_DONE();
372 }
373
374 void
375 devstat_end_transaction_bio(struct devstat *ds, struct bio *bp)
376 {
377 devstat_trans_flags flg;
378
379 /* sanity check */
380 if (ds == NULL)
381 return;
382
383 if (bp->bio_cmd == BIO_DELETE)
384 flg = DEVSTAT_FREE;
385 else if (bp->bio_cmd == BIO_READ)
386 flg = DEVSTAT_READ;
387 else if (bp->bio_cmd == BIO_WRITE)
388 flg = DEVSTAT_WRITE;
389 else
390 flg = DEVSTAT_NO_DATA;
391
392 devstat_end_transaction(ds, bp->bio_bcount - bp->bio_resid,
393 DEVSTAT_TAG_SIMPLE, flg, NULL, &bp->bio_t0);
394 DTRACE_DEVSTAT_BIO_DONE();
395 }
396
397 /*
398 * This is the sysctl handler for the devstat package. The data pushed out
399 * on the kern.devstat.all sysctl variable consists of the current devstat
400 * generation number, and then an array of devstat structures, one for each
401 * device in the system.
402 *
403 * This is more cryptic that obvious, but basically we neither can nor
404 * want to hold the devstat_mutex for any amount of time, so we grab it
405 * only when we need to and keep an eye on devstat_generation all the time.
406 */
407 static int
408 sysctl_devstat(SYSCTL_HANDLER_ARGS)
409 {
410 int error;
411 long mygen;
412 struct devstat *nds;
413
414 mtx_assert(&devstat_mutex, MA_NOTOWNED);
415
416 /*
417 * XXX devstat_generation should really be "volatile" but that
418 * XXX freaks out the sysctl macro below. The places where we
419 * XXX change it and inspect it are bracketed in the mutex which
420 * XXX guarantees us proper write barriers. I don't belive the
421 * XXX compiler is allowed to optimize mygen away across calls
422 * XXX to other functions, so the following is belived to be safe.
423 */
424 mygen = devstat_generation;
425
426 error = SYSCTL_OUT(req, &mygen, sizeof(mygen));
427
428 if (devstat_num_devs == 0)
429 return(0);
430
431 if (error != 0)
432 return (error);
433
434 mtx_lock(&devstat_mutex);
435 nds = STAILQ_FIRST(&device_statq);
436 if (mygen != devstat_generation)
437 error = EBUSY;
438 mtx_unlock(&devstat_mutex);
439
440 if (error != 0)
441 return (error);
442
443 for (;nds != NULL;) {
444 error = SYSCTL_OUT(req, nds, sizeof(struct devstat));
445 if (error != 0)
446 return (error);
447 mtx_lock(&devstat_mutex);
448 if (mygen != devstat_generation)
449 error = EBUSY;
450 else
451 nds = STAILQ_NEXT(nds, dev_links);
452 mtx_unlock(&devstat_mutex);
453 if (error != 0)
454 return (error);
455 }
456 return(error);
457 }
458
459 /*
460 * Sysctl entries for devstat. The first one is a node that all the rest
461 * hang off of.
462 */
463 static SYSCTL_NODE(_kern, OID_AUTO, devstat, CTLFLAG_RD, NULL,
464 "Device Statistics");
465
466 SYSCTL_PROC(_kern_devstat, OID_AUTO, all, CTLFLAG_RD|CTLTYPE_OPAQUE,
467 NULL, 0, sysctl_devstat, "S,devstat", "All devices in the devstat list");
468 /*
469 * Export the number of devices in the system so that userland utilities
470 * can determine how much memory to allocate to hold all the devices.
471 */
472 SYSCTL_INT(_kern_devstat, OID_AUTO, numdevs, CTLFLAG_RD,
473 &devstat_num_devs, 0, "Number of devices in the devstat list");
474 SYSCTL_LONG(_kern_devstat, OID_AUTO, generation, CTLFLAG_RD,
475 &devstat_generation, 0, "Devstat list generation");
476 SYSCTL_INT(_kern_devstat, OID_AUTO, version, CTLFLAG_RD,
477 &devstat_version, 0, "Devstat list version number");
478
479 /*
480 * Allocator for struct devstat structures. We sub-allocate these from pages
481 * which we get from malloc. These pages are exported for mmap(2)'ing through
482 * a miniature device driver
483 */
484
485 #define statsperpage (PAGE_SIZE / sizeof(struct devstat))
486
487 static d_mmap_t devstat_mmap;
488
489 static struct cdevsw devstat_cdevsw = {
490 .d_version = D_VERSION,
491 .d_flags = D_NEEDGIANT,
492 .d_mmap = devstat_mmap,
493 .d_name = "devstat",
494 };
495
496 struct statspage {
497 TAILQ_ENTRY(statspage) list;
498 struct devstat *stat;
499 u_int nfree;
500 };
501
502 static TAILQ_HEAD(, statspage) pagelist = TAILQ_HEAD_INITIALIZER(pagelist);
503 static MALLOC_DEFINE(M_DEVSTAT, "devstat", "Device statistics");
504
505 static int
506 devstat_mmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
507 int nprot, vm_memattr_t *memattr)
508 {
509 struct statspage *spp;
510
511 if (nprot != VM_PROT_READ)
512 return (-1);
513 TAILQ_FOREACH(spp, &pagelist, list) {
514 if (offset == 0) {
515 *paddr = vtophys(spp->stat);
516 return (0);
517 }
518 offset -= PAGE_SIZE;
519 }
520 return (-1);
521 }
522
523 static struct devstat *
524 devstat_alloc(void)
525 {
526 struct devstat *dsp;
527 struct statspage *spp, *spp2;
528 u_int u;
529 static int once;
530
531 mtx_assert(&devstat_mutex, MA_NOTOWNED);
532 if (!once) {
533 make_dev_credf(MAKEDEV_ETERNAL | MAKEDEV_CHECKNAME,
534 &devstat_cdevsw, 0, NULL, UID_ROOT, GID_WHEEL, 0400,
535 DEVSTAT_DEVICE_NAME);
536 once = 1;
537 }
538 spp2 = NULL;
539 mtx_lock(&devstat_mutex);
540 for (;;) {
541 TAILQ_FOREACH(spp, &pagelist, list) {
542 if (spp->nfree > 0)
543 break;
544 }
545 if (spp != NULL)
546 break;
547 mtx_unlock(&devstat_mutex);
548 spp2 = malloc(sizeof *spp, M_DEVSTAT, M_ZERO | M_WAITOK);
549 spp2->stat = malloc(PAGE_SIZE, M_DEVSTAT, M_ZERO | M_WAITOK);
550 spp2->nfree = statsperpage;
551
552 /*
553 * If free statspages were added while the lock was released
554 * just reuse them.
555 */
556 mtx_lock(&devstat_mutex);
557 TAILQ_FOREACH(spp, &pagelist, list)
558 if (spp->nfree > 0)
559 break;
560 if (spp == NULL) {
561 spp = spp2;
562
563 /*
564 * It would make more sense to add the new page at the
565 * head but the order on the list determine the
566 * sequence of the mapping so we can't do that.
567 */
568 TAILQ_INSERT_TAIL(&pagelist, spp, list);
569 } else
570 break;
571 }
572 dsp = spp->stat;
573 for (u = 0; u < statsperpage; u++) {
574 if (dsp->allocated == 0)
575 break;
576 dsp++;
577 }
578 spp->nfree--;
579 dsp->allocated = 1;
580 mtx_unlock(&devstat_mutex);
581 if (spp2 != NULL && spp2 != spp) {
582 free(spp2->stat, M_DEVSTAT);
583 free(spp2, M_DEVSTAT);
584 }
585 return (dsp);
586 }
587
588 static void
589 devstat_free(struct devstat *dsp)
590 {
591 struct statspage *spp;
592
593 mtx_assert(&devstat_mutex, MA_OWNED);
594 bzero(dsp, sizeof *dsp);
595 TAILQ_FOREACH(spp, &pagelist, list) {
596 if (dsp >= spp->stat && dsp < (spp->stat + statsperpage)) {
597 spp->nfree++;
598 return;
599 }
600 }
601 }
602
603 SYSCTL_INT(_debug_sizeof, OID_AUTO, devstat, CTLFLAG_RD,
604 NULL, sizeof(struct devstat), "sizeof(struct devstat)");
Cache object: 5805603a8627b7477d81beff82a80fb8
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