xref: /freebsd/lib/libthr/thread/thr_attr.c (revision f4b37ed0f8b307b1f3f0f630ca725d68f1dff30d)
1 /*
2  * Copyright (c) 2003 Craig Rodrigues <rodrigc@attbi.com>.
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. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by Craig Rodrigues.
16  * 4. Neither the name of the author nor the names of any co-contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY CRAIG RODRIGUES AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  *
32  */
33 
34 /*
35  * Copyright (c) 1998 Daniel Eischen <eischen@vigrid.com>.
36  * Copyright (C) 2001 Jason Evans <jasone@freebsd.org>.
37  * Copyright (c) 2002,2003 Alexey Zelkin <phantom@FreeBSD.org>
38  * All rights reserved.
39  *
40  * Redistribution and use in source and binary forms, with or without
41  * modification, are permitted provided that the following conditions
42  * are met:
43  * 1. Redistributions of source code must retain the above copyright
44  *    notice(s), this list of conditions and the following disclaimer
45  *    unmodified other than the allowable addition of one or more
46  *    copyright notices.
47  * 2. Redistributions in binary form must reproduce the above copyright
48  *    notice(s), this list of conditions and the following disclaimer in
49  *    the documentation and/or other materials provided with the
50  *    distribution.
51  *
52  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
53  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
54  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
55  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
56  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
57  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
58  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
59  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
60  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
61  * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
62  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
63  */
64 
65 /*
66  * Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>.
67  * All rights reserved.
68  *
69  * Redistribution and use in source and binary forms, with or without
70  * modification, are permitted provided that the following conditions
71  * are met:
72  * 1. Redistributions of source code must retain the above copyright
73  *    notice, this list of conditions and the following disclaimer.
74  * 2. Redistributions in binary form must reproduce the above copyright
75  *    notice, this list of conditions and the following disclaimer in the
76  *    documentation and/or other materials provided with the distribution.
77  * 3. Neither the name of the author nor the names of any co-contributors
78  *    may be used to endorse or promote products derived from this software
79  *    without specific prior written permission.
80  *
81  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
82  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
83  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
84  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
85  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
86  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
87  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
88  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
89  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
90  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
91  * SUCH DAMAGE.
92  *
93  * $FreeBSD$
94  */
95 
96 #include "namespace.h"
97 #include <errno.h>
98 #include <pthread.h>
99 #include <stdlib.h>
100 #include <string.h>
101 #include <pthread_np.h>
102 #include <sys/sysctl.h>
103 #include "un-namespace.h"
104 
105 #include "thr_private.h"
106 
107 static size_t	_get_kern_cpuset_size(void);
108 
109 __weak_reference(_pthread_attr_destroy, pthread_attr_destroy);
110 
111 int
112 _pthread_attr_destroy(pthread_attr_t *attr)
113 {
114 	int	ret;
115 
116 	/* Check for invalid arguments: */
117 	if (attr == NULL || *attr == NULL)
118 		/* Invalid argument: */
119 		ret = EINVAL;
120 	else {
121 		if ((*attr)->cpuset != NULL)
122 			free((*attr)->cpuset);
123 		/* Free the memory allocated to the attribute object: */
124 		free(*attr);
125 
126 		/*
127 		 * Leave the attribute pointer NULL now that the memory
128 		 * has been freed:
129 		 */
130 		*attr = NULL;
131 		ret = 0;
132 	}
133 	return(ret);
134 }
135 
136 __weak_reference(_pthread_attr_get_np, pthread_attr_get_np);
137 
138 int
139 _pthread_attr_get_np(pthread_t pthread, pthread_attr_t *dstattr)
140 {
141 	struct pthread *curthread;
142 	struct pthread_attr attr, *dst;
143 	int	ret;
144 	size_t	kern_size;
145 
146 	if (pthread == NULL || dstattr == NULL || (dst = *dstattr) == NULL)
147 		return (EINVAL);
148 	kern_size = _get_kern_cpuset_size();
149 	if (dst->cpuset == NULL) {
150 		dst->cpuset = calloc(1, kern_size);
151 		dst->cpusetsize = kern_size;
152 	}
153 	curthread = _get_curthread();
154 	if ((ret = _thr_find_thread(curthread, pthread, /*include dead*/0)) != 0)
155 		return (ret);
156 	attr = pthread->attr;
157 	if (pthread->flags & THR_FLAGS_DETACHED)
158 		attr.flags |= PTHREAD_DETACHED;
159 	ret = cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_TID, TID(pthread),
160 		dst->cpusetsize, dst->cpuset);
161 	if (ret == -1)
162 		ret = errno;
163 	THR_THREAD_UNLOCK(curthread, pthread);
164 	if (ret == 0) {
165 		memcpy(&dst->pthread_attr_start_copy,
166 			&attr.pthread_attr_start_copy,
167 			offsetof(struct pthread_attr, pthread_attr_end_copy) -
168 			offsetof(struct pthread_attr, pthread_attr_start_copy));
169 	}
170 	return (ret);
171 }
172 
173 __weak_reference(_pthread_attr_getdetachstate, pthread_attr_getdetachstate);
174 
175 int
176 _pthread_attr_getdetachstate(const pthread_attr_t *attr, int *detachstate)
177 {
178 	int	ret;
179 
180 	/* Check for invalid arguments: */
181 	if (attr == NULL || *attr == NULL || detachstate == NULL)
182 		ret = EINVAL;
183 	else {
184 		/* Check if the detached flag is set: */
185 		if ((*attr)->flags & PTHREAD_DETACHED)
186 			/* Return detached: */
187 			*detachstate = PTHREAD_CREATE_DETACHED;
188 		else
189 			/* Return joinable: */
190 			*detachstate = PTHREAD_CREATE_JOINABLE;
191 		ret = 0;
192 	}
193 	return(ret);
194 }
195 
196 __weak_reference(_pthread_attr_getguardsize, pthread_attr_getguardsize);
197 
198 int
199 _pthread_attr_getguardsize(const pthread_attr_t *attr, size_t *guardsize)
200 {
201 	int	ret;
202 
203 	/* Check for invalid arguments: */
204 	if (attr == NULL || *attr == NULL || guardsize == NULL)
205 		ret = EINVAL;
206 	else {
207 		/* Return the guard size: */
208 		*guardsize = (*attr)->guardsize_attr;
209 		ret = 0;
210 	}
211 	return(ret);
212 }
213 
214 __weak_reference(_pthread_attr_getinheritsched, pthread_attr_getinheritsched);
215 
216 int
217 _pthread_attr_getinheritsched(const pthread_attr_t *attr, int *sched_inherit)
218 {
219 	int ret = 0;
220 
221 	if ((attr == NULL) || (*attr == NULL))
222 		ret = EINVAL;
223 	else
224 		*sched_inherit = (*attr)->sched_inherit;
225 
226 	return(ret);
227 }
228 
229 __weak_reference(_pthread_attr_getschedparam, pthread_attr_getschedparam);
230 
231 int
232 _pthread_attr_getschedparam(const pthread_attr_t *attr, struct sched_param *param)
233 {
234 	int ret = 0;
235 
236 	if ((attr == NULL) || (*attr == NULL) || (param == NULL))
237 		ret = EINVAL;
238 	else
239 		param->sched_priority = (*attr)->prio;
240 
241 	return(ret);
242 }
243 
244 __weak_reference(_pthread_attr_getschedpolicy, pthread_attr_getschedpolicy);
245 
246 int
247 _pthread_attr_getschedpolicy(const pthread_attr_t *attr, int *policy)
248 {
249 	int ret = 0;
250 
251 	if ((attr == NULL) || (*attr == NULL) || (policy == NULL))
252 		ret = EINVAL;
253 	else
254 		*policy = (*attr)->sched_policy;
255 
256 	return(ret);
257 }
258 
259 __weak_reference(_pthread_attr_getscope, pthread_attr_getscope);
260 
261 int
262 _pthread_attr_getscope(const pthread_attr_t *attr, int *contentionscope)
263 {
264 	int ret = 0;
265 
266 	if ((attr == NULL) || (*attr == NULL) || (contentionscope == NULL))
267 		/* Return an invalid argument: */
268 		ret = EINVAL;
269 
270 	else
271 		*contentionscope = (*attr)->flags & PTHREAD_SCOPE_SYSTEM ?
272 		    PTHREAD_SCOPE_SYSTEM : PTHREAD_SCOPE_PROCESS;
273 
274 	return(ret);
275 }
276 
277 __weak_reference(_pthread_attr_getstack, pthread_attr_getstack);
278 
279 int
280 _pthread_attr_getstack(const pthread_attr_t * __restrict attr,
281                         void ** __restrict stackaddr,
282                         size_t * __restrict stacksize)
283 {
284 	int     ret;
285 
286 	/* Check for invalid arguments: */
287 	if (attr == NULL || *attr == NULL || stackaddr == NULL
288 	    || stacksize == NULL )
289 		ret = EINVAL;
290 	else {
291 		/* Return the stack address and size */
292 		*stackaddr = (*attr)->stackaddr_attr;
293 		*stacksize = (*attr)->stacksize_attr;
294 		ret = 0;
295 	}
296 	return(ret);
297 }
298 
299 __weak_reference(_pthread_attr_getstackaddr, pthread_attr_getstackaddr);
300 
301 int
302 _pthread_attr_getstackaddr(const pthread_attr_t *attr, void **stackaddr)
303 {
304 	int	ret;
305 
306 	/* Check for invalid arguments: */
307 	if (attr == NULL || *attr == NULL || stackaddr == NULL)
308 		ret = EINVAL;
309 	else {
310 		/* Return the stack address: */
311 		*stackaddr = (*attr)->stackaddr_attr;
312 		ret = 0;
313 	}
314 	return(ret);
315 }
316 
317 __weak_reference(_pthread_attr_getstacksize, pthread_attr_getstacksize);
318 
319 int
320 _pthread_attr_getstacksize(const pthread_attr_t *attr, size_t *stacksize)
321 {
322 	int	ret;
323 
324 	/* Check for invalid arguments: */
325 	if (attr == NULL || *attr == NULL || stacksize  == NULL)
326 		ret = EINVAL;
327 	else {
328 		/* Return the stack size: */
329 		*stacksize = (*attr)->stacksize_attr;
330 		ret = 0;
331 	}
332 	return(ret);
333 }
334 
335 __weak_reference(_pthread_attr_init, pthread_attr_init);
336 
337 int
338 _pthread_attr_init(pthread_attr_t *attr)
339 {
340 	int	ret;
341 	pthread_attr_t	pattr;
342 
343 	_thr_check_init();
344 
345 	/* Allocate memory for the attribute object: */
346 	if ((pattr = (pthread_attr_t) malloc(sizeof(struct pthread_attr))) == NULL)
347 		/* Insufficient memory: */
348 		ret = ENOMEM;
349 	else {
350 		/* Initialise the attribute object with the defaults: */
351 		memcpy(pattr, &_pthread_attr_default, sizeof(struct pthread_attr));
352 
353 		/* Return a pointer to the attribute object: */
354 		*attr = pattr;
355 		ret = 0;
356 	}
357 	return(ret);
358 }
359 
360 __weak_reference(_pthread_attr_setcreatesuspend_np, pthread_attr_setcreatesuspend_np);
361 
362 int
363 _pthread_attr_setcreatesuspend_np(pthread_attr_t *attr)
364 {
365 	int	ret;
366 
367 	if (attr == NULL || *attr == NULL) {
368 		ret = EINVAL;
369 	} else {
370 		(*attr)->suspend = THR_CREATE_SUSPENDED;
371 		ret = 0;
372 	}
373 	return(ret);
374 }
375 
376 __weak_reference(_pthread_attr_setdetachstate, pthread_attr_setdetachstate);
377 
378 int
379 _pthread_attr_setdetachstate(pthread_attr_t *attr, int detachstate)
380 {
381 	int	ret;
382 
383 	/* Check for invalid arguments: */
384 	if (attr == NULL || *attr == NULL ||
385 	    (detachstate != PTHREAD_CREATE_DETACHED &&
386 	    detachstate != PTHREAD_CREATE_JOINABLE))
387 		ret = EINVAL;
388 	else {
389 		/* Check if detached state: */
390 		if (detachstate == PTHREAD_CREATE_DETACHED)
391 			/* Set the detached flag: */
392 			(*attr)->flags |= PTHREAD_DETACHED;
393 		else
394 			/* Reset the detached flag: */
395 			(*attr)->flags &= ~PTHREAD_DETACHED;
396 		ret = 0;
397 	}
398 	return(ret);
399 }
400 
401 __weak_reference(_pthread_attr_setguardsize, pthread_attr_setguardsize);
402 
403 int
404 _pthread_attr_setguardsize(pthread_attr_t *attr, size_t guardsize)
405 {
406 	int	ret;
407 
408 	/* Check for invalid arguments. */
409 	if (attr == NULL || *attr == NULL)
410 		ret = EINVAL;
411 	else {
412 		/* Save the stack size. */
413 		(*attr)->guardsize_attr = guardsize;
414 		ret = 0;
415 	}
416 	return(ret);
417 }
418 
419 __weak_reference(_pthread_attr_setinheritsched, pthread_attr_setinheritsched);
420 
421 int
422 _pthread_attr_setinheritsched(pthread_attr_t *attr, int sched_inherit)
423 {
424 	int ret = 0;
425 
426 	if ((attr == NULL) || (*attr == NULL))
427 		ret = EINVAL;
428 	else if (sched_inherit != PTHREAD_INHERIT_SCHED &&
429 		 sched_inherit != PTHREAD_EXPLICIT_SCHED)
430 		ret = ENOTSUP;
431 	else
432 		(*attr)->sched_inherit = sched_inherit;
433 
434 	return(ret);
435 }
436 
437 __weak_reference(_pthread_attr_setschedparam, pthread_attr_setschedparam);
438 
439 int
440 _pthread_attr_setschedparam(pthread_attr_t *attr, const struct sched_param *param)
441 {
442 	int policy;
443 
444 	if ((attr == NULL) || (*attr == NULL))
445 		return (EINVAL);
446 
447 	if (param == NULL)
448 		return (ENOTSUP);
449 
450 	policy = (*attr)->sched_policy;
451 
452 	if (policy == SCHED_FIFO || policy == SCHED_RR) {
453 		if (param->sched_priority < _thr_priorities[policy-1].pri_min ||
454 		    param->sched_priority > _thr_priorities[policy-1].pri_max)
455 		return (ENOTSUP);
456 	} else {
457 		/*
458 		 * Ignore it for SCHED_OTHER now, patches for glib ports
459 		 * are wrongly using M:N thread library's internal macro
460 		 * THR_MIN_PRIORITY and THR_MAX_PRIORITY.
461 		 */
462 	}
463 
464 	(*attr)->prio = param->sched_priority;
465 
466 	return (0);
467 }
468 
469 __weak_reference(_pthread_attr_setschedpolicy, pthread_attr_setschedpolicy);
470 
471 int
472 _pthread_attr_setschedpolicy(pthread_attr_t *attr, int policy)
473 {
474 	int ret = 0;
475 
476 	if ((attr == NULL) || (*attr == NULL))
477 		ret = EINVAL;
478 	else if ((policy < SCHED_FIFO) || (policy > SCHED_RR)) {
479 		ret = ENOTSUP;
480 	} else {
481 		(*attr)->sched_policy = policy;
482 		(*attr)->prio = _thr_priorities[policy-1].pri_default;
483 	}
484 	return(ret);
485 }
486 
487 __weak_reference(_pthread_attr_setscope, pthread_attr_setscope);
488 
489 int
490 _pthread_attr_setscope(pthread_attr_t *attr, int contentionscope)
491 {
492 	int ret = 0;
493 
494 	if ((attr == NULL) || (*attr == NULL)) {
495 		/* Return an invalid argument: */
496 		ret = EINVAL;
497 	} else if ((contentionscope != PTHREAD_SCOPE_PROCESS) &&
498 	    (contentionscope != PTHREAD_SCOPE_SYSTEM)) {
499 		ret = EINVAL;
500 	} else if (contentionscope == PTHREAD_SCOPE_SYSTEM) {
501 		(*attr)->flags |= contentionscope;
502 	} else {
503 		(*attr)->flags &= ~PTHREAD_SCOPE_SYSTEM;
504 	}
505 	return (ret);
506 }
507 
508 __weak_reference(_pthread_attr_setstack, pthread_attr_setstack);
509 
510 int
511 _pthread_attr_setstack(pthread_attr_t *attr, void *stackaddr,
512                         size_t stacksize)
513 {
514 	int     ret;
515 
516 	/* Check for invalid arguments: */
517 	if (attr == NULL || *attr == NULL || stackaddr == NULL
518 	    || stacksize < PTHREAD_STACK_MIN)
519 		ret = EINVAL;
520 	else {
521 		/* Save the stack address and stack size */
522 		(*attr)->stackaddr_attr = stackaddr;
523 		(*attr)->stacksize_attr = stacksize;
524 		ret = 0;
525 	}
526 	return(ret);
527 }
528 
529 __weak_reference(_pthread_attr_setstackaddr, pthread_attr_setstackaddr);
530 
531 int
532 _pthread_attr_setstackaddr(pthread_attr_t *attr, void *stackaddr)
533 {
534 	int	ret;
535 
536 	/* Check for invalid arguments: */
537 	if (attr == NULL || *attr == NULL || stackaddr == NULL)
538 		ret = EINVAL;
539 	else {
540 		/* Save the stack address: */
541 		(*attr)->stackaddr_attr = stackaddr;
542 		ret = 0;
543 	}
544 	return(ret);
545 }
546 
547 __weak_reference(_pthread_attr_setstacksize, pthread_attr_setstacksize);
548 
549 int
550 _pthread_attr_setstacksize(pthread_attr_t *attr, size_t stacksize)
551 {
552 	int	ret;
553 
554 	/* Check for invalid arguments: */
555 	if (attr == NULL || *attr == NULL || stacksize < PTHREAD_STACK_MIN)
556 		ret = EINVAL;
557 	else {
558 		/* Save the stack size: */
559 		(*attr)->stacksize_attr = stacksize;
560 		ret = 0;
561 	}
562 	return(ret);
563 }
564 
565 static size_t
566 _get_kern_cpuset_size(void)
567 {
568 	static int kern_cpuset_size = 0;
569 
570 	if (kern_cpuset_size == 0) {
571 		size_t len;
572 
573 		len = sizeof(kern_cpuset_size);
574 		if (sysctlbyname("kern.sched.cpusetsize", &kern_cpuset_size,
575 		    &len, NULL, 0))
576 			PANIC("failed to get sysctl kern.sched.cpusetsize");
577 	}
578 
579 	return (kern_cpuset_size);
580 }
581 
582 __weak_reference(_pthread_attr_setaffinity_np, pthread_attr_setaffinity_np);
583 int
584 _pthread_attr_setaffinity_np(pthread_attr_t *pattr, size_t cpusetsize,
585 	const cpuset_t *cpusetp)
586 {
587 	pthread_attr_t attr;
588 	int ret;
589 
590 	if (pattr == NULL || (attr = (*pattr)) == NULL)
591 		ret = EINVAL;
592 	else {
593 		if (cpusetsize == 0 || cpusetp == NULL) {
594 			if (attr->cpuset != NULL) {
595 				free(attr->cpuset);
596 				attr->cpuset = NULL;
597 				attr->cpusetsize = 0;
598 			}
599 			return (0);
600 		}
601 		size_t kern_size = _get_kern_cpuset_size();
602 		/* Kernel rejects small set, we check it here too. */
603 		if (cpusetsize < kern_size)
604 			return (ERANGE);
605 		if (cpusetsize > kern_size) {
606 			/* Kernel checks invalid bits, we check it here too. */
607 			size_t i;
608 			for (i = kern_size; i < cpusetsize; ++i) {
609 				if (((char *)cpusetp)[i])
610 					return (EINVAL);
611 			}
612 		}
613 		if (attr->cpuset == NULL) {
614 			attr->cpuset = calloc(1, kern_size);
615 			if (attr->cpuset == NULL)
616 				return (errno);
617 			attr->cpusetsize = kern_size;
618 		}
619 		memcpy(attr->cpuset, cpusetp, kern_size);
620 		ret = 0;
621 	}
622 	return (ret);
623 }
624 
625 __weak_reference(_pthread_attr_getaffinity_np, pthread_attr_getaffinity_np);
626 int
627 _pthread_attr_getaffinity_np(const pthread_attr_t *pattr, size_t cpusetsize,
628 	cpuset_t *cpusetp)
629 {
630 	pthread_attr_t attr;
631 	int ret = 0;
632 
633 	if (pattr == NULL || (attr = (*pattr)) == NULL)
634 		ret = EINVAL;
635 	else {
636 		/* Kernel rejects small set, we check it here too. */
637 		size_t kern_size = _get_kern_cpuset_size();
638 		if (cpusetsize < kern_size)
639 			return (ERANGE);
640 		if (attr->cpuset != NULL)
641 			memcpy(cpusetp, attr->cpuset, MIN(cpusetsize,
642 			   attr->cpusetsize));
643 		else
644 			memset(cpusetp, -1, kern_size);
645 		if (cpusetsize > kern_size)
646 			memset(((char *)cpusetp) + kern_size, 0,
647 				cpusetsize - kern_size);
648 	}
649 	return (ret);
650 }
651