xref: /netbsd-src/sys/dev/tprof/tprof.c (revision 181254a7b1bdde6873432bffef2d2decc4b5c22f)
1 /*	$NetBSD: tprof.c,v 1.14 2018/07/13 07:56:29 maxv Exp $	*/
2 
3 /*-
4  * Copyright (c)2008,2009,2010 YAMAMOTO Takashi,
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  *
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 __KERNEL_RCSID(0, "$NetBSD: tprof.c,v 1.14 2018/07/13 07:56:29 maxv Exp $");
31 
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/kernel.h>
35 
36 #include <sys/cpu.h>
37 #include <sys/conf.h>
38 #include <sys/callout.h>
39 #include <sys/kmem.h>
40 #include <sys/module.h>
41 #include <sys/proc.h>
42 #include <sys/workqueue.h>
43 #include <sys/queue.h>
44 
45 #include <dev/tprof/tprof.h>
46 #include <dev/tprof/tprof_ioctl.h>
47 
48 #include "ioconf.h"
49 
50 /*
51  * locking order:
52  *	tprof_reader_lock -> tprof_lock
53  *	tprof_startstop_lock -> tprof_lock
54  */
55 
56 /*
57  * protected by:
58  *	L: tprof_lock
59  *	R: tprof_reader_lock
60  *	S: tprof_startstop_lock
61  *	s: writer should hold tprof_startstop_lock and tprof_lock
62  *	   reader should hold tprof_startstop_lock or tprof_lock
63  */
64 
65 typedef struct tprof_buf {
66 	u_int b_used;
67 	u_int b_size;
68 	u_int b_overflow;
69 	u_int b_unused;
70 	STAILQ_ENTRY(tprof_buf) b_list;
71 	tprof_sample_t b_data[];
72 } tprof_buf_t;
73 #define	TPROF_BUF_BYTESIZE(sz) \
74 	(sizeof(tprof_buf_t) + (sz) * sizeof(tprof_sample_t))
75 #define	TPROF_MAX_SAMPLES_PER_BUF	10000
76 
77 #define	TPROF_MAX_BUF			100
78 
79 typedef struct {
80 	tprof_buf_t *c_buf;
81 	uint32_t c_cpuid;
82 	struct work c_work;
83 	callout_t c_callout;
84 } __aligned(CACHE_LINE_SIZE) tprof_cpu_t;
85 
86 typedef struct tprof_backend {
87 	const char *tb_name;
88 	const tprof_backend_ops_t *tb_ops;
89 	LIST_ENTRY(tprof_backend) tb_list;
90 	int tb_usecount;	/* S: */
91 } tprof_backend_t;
92 
93 static kmutex_t tprof_lock;
94 static bool tprof_running;		/* s: */
95 static u_int tprof_nworker;		/* L: # of running worker LWPs */
96 static lwp_t *tprof_owner;
97 static STAILQ_HEAD(, tprof_buf) tprof_list; /* L: global buffer list */
98 static u_int tprof_nbuf_on_list;	/* L: # of buffers on tprof_list */
99 static struct workqueue *tprof_wq;
100 static tprof_cpu_t tprof_cpus[MAXCPUS] __aligned(CACHE_LINE_SIZE);
101 static u_int tprof_samples_per_buf;
102 
103 static tprof_backend_t *tprof_backend;	/* S: */
104 static LIST_HEAD(, tprof_backend) tprof_backends =
105     LIST_HEAD_INITIALIZER(tprof_backend); /* S: */
106 
107 static kmutex_t tprof_reader_lock;
108 static kcondvar_t tprof_reader_cv;	/* L: */
109 static off_t tprof_reader_offset;	/* R: */
110 
111 static kmutex_t tprof_startstop_lock;
112 static kcondvar_t tprof_cv;		/* L: */
113 
114 static struct tprof_stat tprof_stat;	/* L: */
115 
116 static tprof_cpu_t *
117 tprof_cpu(struct cpu_info *ci)
118 {
119 
120 	return &tprof_cpus[cpu_index(ci)];
121 }
122 
123 static tprof_cpu_t *
124 tprof_curcpu(void)
125 {
126 
127 	return tprof_cpu(curcpu());
128 }
129 
130 static tprof_buf_t *
131 tprof_buf_alloc(void)
132 {
133 	tprof_buf_t *new;
134 	u_int size = tprof_samples_per_buf;
135 
136 	new = kmem_alloc(TPROF_BUF_BYTESIZE(size), KM_SLEEP);
137 	new->b_used = 0;
138 	new->b_size = size;
139 	new->b_overflow = 0;
140 	return new;
141 }
142 
143 static void
144 tprof_buf_free(tprof_buf_t *buf)
145 {
146 
147 	kmem_free(buf, TPROF_BUF_BYTESIZE(buf->b_size));
148 }
149 
150 static tprof_buf_t *
151 tprof_buf_switch(tprof_cpu_t *c, tprof_buf_t *new)
152 {
153 	tprof_buf_t *old;
154 
155 	old = c->c_buf;
156 	c->c_buf = new;
157 	return old;
158 }
159 
160 static tprof_buf_t *
161 tprof_buf_refresh(void)
162 {
163 	tprof_cpu_t * const c = tprof_curcpu();
164 	tprof_buf_t *new;
165 
166 	new = tprof_buf_alloc();
167 	return tprof_buf_switch(c, new);
168 }
169 
170 static void
171 tprof_worker(struct work *wk, void *dummy)
172 {
173 	tprof_cpu_t * const c = tprof_curcpu();
174 	tprof_buf_t *buf;
175 	bool shouldstop;
176 
177 	KASSERT(wk == &c->c_work);
178 	KASSERT(dummy == NULL);
179 
180 	/*
181 	 * get a per cpu buffer.
182 	 */
183 	buf = tprof_buf_refresh();
184 
185 	/*
186 	 * and put it on the global list for read(2).
187 	 */
188 	mutex_enter(&tprof_lock);
189 	shouldstop = !tprof_running;
190 	if (shouldstop) {
191 		KASSERT(tprof_nworker > 0);
192 		tprof_nworker--;
193 		cv_broadcast(&tprof_cv);
194 		cv_broadcast(&tprof_reader_cv);
195 	}
196 	if (buf->b_used == 0) {
197 		tprof_stat.ts_emptybuf++;
198 	} else if (tprof_nbuf_on_list < TPROF_MAX_BUF) {
199 		tprof_stat.ts_sample += buf->b_used;
200 		tprof_stat.ts_overflow += buf->b_overflow;
201 		tprof_stat.ts_buf++;
202 		STAILQ_INSERT_TAIL(&tprof_list, buf, b_list);
203 		tprof_nbuf_on_list++;
204 		buf = NULL;
205 		cv_broadcast(&tprof_reader_cv);
206 	} else {
207 		tprof_stat.ts_dropbuf_sample += buf->b_used;
208 		tprof_stat.ts_dropbuf++;
209 	}
210 	mutex_exit(&tprof_lock);
211 	if (buf) {
212 		tprof_buf_free(buf);
213 	}
214 	if (!shouldstop) {
215 		callout_schedule(&c->c_callout, hz);
216 	}
217 }
218 
219 static void
220 tprof_kick(void *vp)
221 {
222 	struct cpu_info * const ci = vp;
223 	tprof_cpu_t * const c = tprof_cpu(ci);
224 
225 	workqueue_enqueue(tprof_wq, &c->c_work, ci);
226 }
227 
228 static void
229 tprof_stop1(void)
230 {
231 	CPU_INFO_ITERATOR cii;
232 	struct cpu_info *ci;
233 
234 	KASSERT(mutex_owned(&tprof_startstop_lock));
235 	KASSERT(tprof_nworker == 0);
236 
237 	for (CPU_INFO_FOREACH(cii, ci)) {
238 		tprof_cpu_t * const c = tprof_cpu(ci);
239 		tprof_buf_t *old;
240 
241 		old = tprof_buf_switch(c, NULL);
242 		if (old != NULL) {
243 			tprof_buf_free(old);
244 		}
245 		callout_destroy(&c->c_callout);
246 	}
247 	workqueue_destroy(tprof_wq);
248 }
249 
250 static void
251 tprof_getinfo(struct tprof_info *info)
252 {
253 	tprof_backend_t *tb;
254 
255 	KASSERT(mutex_owned(&tprof_startstop_lock));
256 
257 	memset(info, 0, sizeof(*info));
258 	info->ti_version = TPROF_VERSION;
259 	if ((tb = tprof_backend) != NULL) {
260 		info->ti_ident = tb->tb_ops->tbo_ident();
261 	}
262 }
263 
264 static int
265 tprof_start(const tprof_param_t *param)
266 {
267 	CPU_INFO_ITERATOR cii;
268 	struct cpu_info *ci;
269 	int error;
270 	uint64_t freq;
271 	tprof_backend_t *tb;
272 
273 	KASSERT(mutex_owned(&tprof_startstop_lock));
274 	if (tprof_running) {
275 		error = EBUSY;
276 		goto done;
277 	}
278 
279 	tb = tprof_backend;
280 	if (tb == NULL) {
281 		error = ENOENT;
282 		goto done;
283 	}
284 	if (tb->tb_usecount > 0) {
285 		error = EBUSY;
286 		goto done;
287 	}
288 
289 	tb->tb_usecount++;
290 	freq = tb->tb_ops->tbo_estimate_freq();
291 	tprof_samples_per_buf = MIN(freq * 2, TPROF_MAX_SAMPLES_PER_BUF);
292 
293 	error = workqueue_create(&tprof_wq, "tprofmv", tprof_worker, NULL,
294 	    PRI_NONE, IPL_SOFTCLOCK, WQ_MPSAFE | WQ_PERCPU);
295 	if (error != 0) {
296 		goto done;
297 	}
298 
299 	for (CPU_INFO_FOREACH(cii, ci)) {
300 		tprof_cpu_t * const c = tprof_cpu(ci);
301 		tprof_buf_t *new;
302 		tprof_buf_t *old;
303 
304 		new = tprof_buf_alloc();
305 		old = tprof_buf_switch(c, new);
306 		if (old != NULL) {
307 			tprof_buf_free(old);
308 		}
309 		callout_init(&c->c_callout, CALLOUT_MPSAFE);
310 		callout_setfunc(&c->c_callout, tprof_kick, ci);
311 	}
312 
313 	error = tb->tb_ops->tbo_start(param);
314 	if (error != 0) {
315 		KASSERT(tb->tb_usecount > 0);
316 		tb->tb_usecount--;
317 		tprof_stop1();
318 		goto done;
319 	}
320 
321 	mutex_enter(&tprof_lock);
322 	tprof_running = true;
323 	mutex_exit(&tprof_lock);
324 	for (CPU_INFO_FOREACH(cii, ci)) {
325 		tprof_cpu_t * const c = tprof_cpu(ci);
326 
327 		mutex_enter(&tprof_lock);
328 		tprof_nworker++;
329 		mutex_exit(&tprof_lock);
330 		workqueue_enqueue(tprof_wq, &c->c_work, ci);
331 	}
332 done:
333 	return error;
334 }
335 
336 static void
337 tprof_stop(void)
338 {
339 	tprof_backend_t *tb;
340 
341 	KASSERT(mutex_owned(&tprof_startstop_lock));
342 	if (!tprof_running) {
343 		goto done;
344 	}
345 
346 	tb = tprof_backend;
347 	KASSERT(tb->tb_usecount > 0);
348 	tb->tb_ops->tbo_stop(NULL);
349 	tb->tb_usecount--;
350 
351 	mutex_enter(&tprof_lock);
352 	tprof_running = false;
353 	cv_broadcast(&tprof_reader_cv);
354 	while (tprof_nworker > 0) {
355 		cv_wait(&tprof_cv, &tprof_lock);
356 	}
357 	mutex_exit(&tprof_lock);
358 
359 	tprof_stop1();
360 done:
361 	;
362 }
363 
364 /*
365  * tprof_clear: drain unread samples.
366  */
367 
368 static void
369 tprof_clear(void)
370 {
371 	tprof_buf_t *buf;
372 
373 	mutex_enter(&tprof_reader_lock);
374 	mutex_enter(&tprof_lock);
375 	while ((buf = STAILQ_FIRST(&tprof_list)) != NULL) {
376 		if (buf != NULL) {
377 			STAILQ_REMOVE_HEAD(&tprof_list, b_list);
378 			KASSERT(tprof_nbuf_on_list > 0);
379 			tprof_nbuf_on_list--;
380 			mutex_exit(&tprof_lock);
381 			tprof_buf_free(buf);
382 			mutex_enter(&tprof_lock);
383 		}
384 	}
385 	KASSERT(tprof_nbuf_on_list == 0);
386 	mutex_exit(&tprof_lock);
387 	tprof_reader_offset = 0;
388 	mutex_exit(&tprof_reader_lock);
389 
390 	memset(&tprof_stat, 0, sizeof(tprof_stat));
391 }
392 
393 static tprof_backend_t *
394 tprof_backend_lookup(const char *name)
395 {
396 	tprof_backend_t *tb;
397 
398 	KASSERT(mutex_owned(&tprof_startstop_lock));
399 
400 	LIST_FOREACH(tb, &tprof_backends, tb_list) {
401 		if (!strcmp(tb->tb_name, name)) {
402 			return tb;
403 		}
404 	}
405 	return NULL;
406 }
407 
408 /* -------------------- backend interfaces */
409 
410 /*
411  * tprof_sample: record a sample on the per-cpu buffer.
412  *
413  * be careful; can be called in NMI context.
414  * we are bluntly assuming the followings are safe.
415  *	curcpu()
416  *	curlwp->l_lid
417  *	curlwp->l_proc->p_pid
418  */
419 
420 void
421 tprof_sample(void *unused, const tprof_frame_info_t *tfi)
422 {
423 	tprof_cpu_t * const c = tprof_curcpu();
424 	tprof_buf_t * const buf = c->c_buf;
425 	tprof_sample_t *sp;
426 	const uintptr_t pc = tfi->tfi_pc;
427 	const lwp_t * const l = curlwp;
428 	u_int idx;
429 
430 	idx = buf->b_used;
431 	if (__predict_false(idx >= buf->b_size)) {
432 		buf->b_overflow++;
433 		return;
434 	}
435 	sp = &buf->b_data[idx];
436 	sp->s_pid = l->l_proc->p_pid;
437 	sp->s_lwpid = l->l_lid;
438 	sp->s_cpuid = c->c_cpuid;
439 	sp->s_flags = (tfi->tfi_inkernel) ? TPROF_SAMPLE_INKERNEL : 0;
440 	sp->s_pc = pc;
441 	buf->b_used = idx + 1;
442 }
443 
444 /*
445  * tprof_backend_register:
446  */
447 
448 int
449 tprof_backend_register(const char *name, const tprof_backend_ops_t *ops,
450     int vers)
451 {
452 	tprof_backend_t *tb;
453 
454 	if (vers != TPROF_BACKEND_VERSION) {
455 		return EINVAL;
456 	}
457 
458 	mutex_enter(&tprof_startstop_lock);
459 	tb = tprof_backend_lookup(name);
460 	if (tb != NULL) {
461 		mutex_exit(&tprof_startstop_lock);
462 		return EEXIST;
463 	}
464 #if 1 /* XXX for now */
465 	if (!LIST_EMPTY(&tprof_backends)) {
466 		mutex_exit(&tprof_startstop_lock);
467 		return ENOTSUP;
468 	}
469 #endif
470 	tb = kmem_alloc(sizeof(*tb), KM_SLEEP);
471 	tb->tb_name = name;
472 	tb->tb_ops = ops;
473 	tb->tb_usecount = 0;
474 	LIST_INSERT_HEAD(&tprof_backends, tb, tb_list);
475 #if 1 /* XXX for now */
476 	if (tprof_backend == NULL) {
477 		tprof_backend = tb;
478 	}
479 #endif
480 	mutex_exit(&tprof_startstop_lock);
481 
482 	return 0;
483 }
484 
485 /*
486  * tprof_backend_unregister:
487  */
488 
489 int
490 tprof_backend_unregister(const char *name)
491 {
492 	tprof_backend_t *tb;
493 
494 	mutex_enter(&tprof_startstop_lock);
495 	tb = tprof_backend_lookup(name);
496 #if defined(DIAGNOSTIC)
497 	if (tb == NULL) {
498 		mutex_exit(&tprof_startstop_lock);
499 		panic("%s: not found '%s'", __func__, name);
500 	}
501 #endif /* defined(DIAGNOSTIC) */
502 	if (tb->tb_usecount > 0) {
503 		mutex_exit(&tprof_startstop_lock);
504 		return EBUSY;
505 	}
506 #if 1 /* XXX for now */
507 	if (tprof_backend == tb) {
508 		tprof_backend = NULL;
509 	}
510 #endif
511 	LIST_REMOVE(tb, tb_list);
512 	mutex_exit(&tprof_startstop_lock);
513 
514 	kmem_free(tb, sizeof(*tb));
515 
516 	return 0;
517 }
518 
519 /* -------------------- cdevsw interfaces */
520 
521 static int
522 tprof_open(dev_t dev, int flags, int type, struct lwp *l)
523 {
524 
525 	if (minor(dev) != 0) {
526 		return EXDEV;
527 	}
528 	mutex_enter(&tprof_lock);
529 	if (tprof_owner != NULL) {
530 		mutex_exit(&tprof_lock);
531 		return  EBUSY;
532 	}
533 	tprof_owner = curlwp;
534 	mutex_exit(&tprof_lock);
535 
536 	return 0;
537 }
538 
539 static int
540 tprof_close(dev_t dev, int flags, int type, struct lwp *l)
541 {
542 
543 	KASSERT(minor(dev) == 0);
544 
545 	mutex_enter(&tprof_startstop_lock);
546 	mutex_enter(&tprof_lock);
547 	tprof_owner = NULL;
548 	mutex_exit(&tprof_lock);
549 	tprof_stop();
550 	tprof_clear();
551 	mutex_exit(&tprof_startstop_lock);
552 
553 	return 0;
554 }
555 
556 static int
557 tprof_read(dev_t dev, struct uio *uio, int flags)
558 {
559 	tprof_buf_t *buf;
560 	size_t bytes;
561 	size_t resid;
562 	size_t done;
563 	int error = 0;
564 
565 	KASSERT(minor(dev) == 0);
566 	mutex_enter(&tprof_reader_lock);
567 	while (uio->uio_resid > 0 && error == 0) {
568 		/*
569 		 * take the first buffer from the list.
570 		 */
571 		mutex_enter(&tprof_lock);
572 		buf = STAILQ_FIRST(&tprof_list);
573 		if (buf == NULL) {
574 			if (tprof_nworker == 0) {
575 				mutex_exit(&tprof_lock);
576 				error = 0;
577 				break;
578 			}
579 			mutex_exit(&tprof_reader_lock);
580 			error = cv_wait_sig(&tprof_reader_cv, &tprof_lock);
581 			mutex_exit(&tprof_lock);
582 			mutex_enter(&tprof_reader_lock);
583 			continue;
584 		}
585 		STAILQ_REMOVE_HEAD(&tprof_list, b_list);
586 		KASSERT(tprof_nbuf_on_list > 0);
587 		tprof_nbuf_on_list--;
588 		mutex_exit(&tprof_lock);
589 
590 		/*
591 		 * copy it out.
592 		 */
593 		bytes = MIN(buf->b_used * sizeof(tprof_sample_t) -
594 		    tprof_reader_offset, uio->uio_resid);
595 		resid = uio->uio_resid;
596 		error = uiomove((char *)buf->b_data + tprof_reader_offset,
597 		    bytes, uio);
598 		done = resid - uio->uio_resid;
599 		tprof_reader_offset += done;
600 
601 		/*
602 		 * if we didn't consume the whole buffer,
603 		 * put it back to the list.
604 		 */
605 		if (tprof_reader_offset <
606 		    buf->b_used * sizeof(tprof_sample_t)) {
607 			mutex_enter(&tprof_lock);
608 			STAILQ_INSERT_HEAD(&tprof_list, buf, b_list);
609 			tprof_nbuf_on_list++;
610 			cv_broadcast(&tprof_reader_cv);
611 			mutex_exit(&tprof_lock);
612 		} else {
613 			tprof_buf_free(buf);
614 			tprof_reader_offset = 0;
615 		}
616 	}
617 	mutex_exit(&tprof_reader_lock);
618 
619 	return error;
620 }
621 
622 static int
623 tprof_ioctl(dev_t dev, u_long cmd, void *data, int flags, struct lwp *l)
624 {
625 	const tprof_param_t *param;
626 	int error = 0;
627 
628 	KASSERT(minor(dev) == 0);
629 
630 	switch (cmd) {
631 	case TPROF_IOC_GETINFO:
632 		mutex_enter(&tprof_startstop_lock);
633 		tprof_getinfo(data);
634 		mutex_exit(&tprof_startstop_lock);
635 		break;
636 	case TPROF_IOC_START:
637 		param = data;
638 		mutex_enter(&tprof_startstop_lock);
639 		error = tprof_start(param);
640 		mutex_exit(&tprof_startstop_lock);
641 		break;
642 	case TPROF_IOC_STOP:
643 		mutex_enter(&tprof_startstop_lock);
644 		tprof_stop();
645 		mutex_exit(&tprof_startstop_lock);
646 		break;
647 	case TPROF_IOC_GETSTAT:
648 		mutex_enter(&tprof_lock);
649 		memcpy(data, &tprof_stat, sizeof(tprof_stat));
650 		mutex_exit(&tprof_lock);
651 		break;
652 	default:
653 		error = EINVAL;
654 		break;
655 	}
656 
657 	return error;
658 }
659 
660 const struct cdevsw tprof_cdevsw = {
661 	.d_open = tprof_open,
662 	.d_close = tprof_close,
663 	.d_read = tprof_read,
664 	.d_write = nowrite,
665 	.d_ioctl = tprof_ioctl,
666 	.d_stop = nostop,
667 	.d_tty = notty,
668 	.d_poll = nopoll,
669 	.d_mmap = nommap,
670 	.d_kqfilter = nokqfilter,
671 	.d_discard = nodiscard,
672 	.d_flag = D_OTHER | D_MPSAFE
673 };
674 
675 void
676 tprofattach(int nunits)
677 {
678 
679 	/* nothing */
680 }
681 
682 MODULE(MODULE_CLASS_DRIVER, tprof, NULL);
683 
684 static void
685 tprof_driver_init(void)
686 {
687 	unsigned int i;
688 
689 	mutex_init(&tprof_lock, MUTEX_DEFAULT, IPL_NONE);
690 	mutex_init(&tprof_reader_lock, MUTEX_DEFAULT, IPL_NONE);
691 	mutex_init(&tprof_startstop_lock, MUTEX_DEFAULT, IPL_NONE);
692 	cv_init(&tprof_cv, "tprof");
693 	cv_init(&tprof_reader_cv, "tprof_rd");
694 	STAILQ_INIT(&tprof_list);
695 	for (i = 0; i < __arraycount(tprof_cpus); i++) {
696 		tprof_cpu_t * const c = &tprof_cpus[i];
697 
698 		c->c_buf = NULL;
699 		c->c_cpuid = i;
700 	}
701 }
702 
703 static void
704 tprof_driver_fini(void)
705 {
706 
707 	mutex_destroy(&tprof_lock);
708 	mutex_destroy(&tprof_reader_lock);
709 	mutex_destroy(&tprof_startstop_lock);
710 	cv_destroy(&tprof_cv);
711 	cv_destroy(&tprof_reader_cv);
712 }
713 
714 static int
715 tprof_modcmd(modcmd_t cmd, void *arg)
716 {
717 
718 	switch (cmd) {
719 	case MODULE_CMD_INIT:
720 		tprof_driver_init();
721 #if defined(_MODULE)
722 		{
723 			devmajor_t bmajor = NODEVMAJOR;
724 			devmajor_t cmajor = NODEVMAJOR;
725 			int error;
726 
727 			error = devsw_attach("tprof", NULL, &bmajor,
728 			    &tprof_cdevsw, &cmajor);
729 			if (error) {
730 				tprof_driver_fini();
731 				return error;
732 			}
733 		}
734 #endif /* defined(_MODULE) */
735 		return 0;
736 
737 	case MODULE_CMD_FINI:
738 #if defined(_MODULE)
739 		{
740 			int error;
741 			error = devsw_detach(NULL, &tprof_cdevsw);
742 			if (error) {
743 				return error;
744 			}
745 		}
746 #endif /* defined(_MODULE) */
747 		tprof_driver_fini();
748 		return 0;
749 
750 	default:
751 		return ENOTTY;
752 	}
753 }
754