xref: /freebsd/sys/kern/kern_resource.c (revision 884a2a699669ec61e2366e3e358342dbc94be24a)
1 /*-
2  * Copyright (c) 1982, 1986, 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  * (c) UNIX System Laboratories, Inc.
5  * All or some portions of this file are derived from material licensed
6  * to the University of California by American Telephone and Telegraph
7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8  * the permission of UNIX System Laboratories, Inc.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 4. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  *
34  *	@(#)kern_resource.c	8.5 (Berkeley) 1/21/94
35  */
36 
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
39 
40 #include "opt_compat.h"
41 
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/sysproto.h>
45 #include <sys/file.h>
46 #include <sys/kernel.h>
47 #include <sys/lock.h>
48 #include <sys/malloc.h>
49 #include <sys/mutex.h>
50 #include <sys/priv.h>
51 #include <sys/proc.h>
52 #include <sys/refcount.h>
53 #include <sys/racct.h>
54 #include <sys/resourcevar.h>
55 #include <sys/rwlock.h>
56 #include <sys/sched.h>
57 #include <sys/sx.h>
58 #include <sys/syscallsubr.h>
59 #include <sys/sysent.h>
60 #include <sys/time.h>
61 #include <sys/umtx.h>
62 
63 #include <vm/vm.h>
64 #include <vm/vm_param.h>
65 #include <vm/pmap.h>
66 #include <vm/vm_map.h>
67 
68 
69 static MALLOC_DEFINE(M_PLIMIT, "plimit", "plimit structures");
70 static MALLOC_DEFINE(M_UIDINFO, "uidinfo", "uidinfo structures");
71 #define	UIHASH(uid)	(&uihashtbl[(uid) & uihash])
72 static struct rwlock uihashtbl_lock;
73 static LIST_HEAD(uihashhead, uidinfo) *uihashtbl;
74 static u_long uihash;		/* size of hash table - 1 */
75 
76 static void	calcru1(struct proc *p, struct rusage_ext *ruxp,
77 		    struct timeval *up, struct timeval *sp);
78 static int	donice(struct thread *td, struct proc *chgp, int n);
79 static struct uidinfo *uilookup(uid_t uid);
80 static void	ruxagg_locked(struct rusage_ext *rux, struct thread *td);
81 
82 /*
83  * Resource controls and accounting.
84  */
85 #ifndef _SYS_SYSPROTO_H_
86 struct getpriority_args {
87 	int	which;
88 	int	who;
89 };
90 #endif
91 int
92 getpriority(td, uap)
93 	struct thread *td;
94 	register struct getpriority_args *uap;
95 {
96 	struct proc *p;
97 	struct pgrp *pg;
98 	int error, low;
99 
100 	error = 0;
101 	low = PRIO_MAX + 1;
102 	switch (uap->which) {
103 
104 	case PRIO_PROCESS:
105 		if (uap->who == 0)
106 			low = td->td_proc->p_nice;
107 		else {
108 			p = pfind(uap->who);
109 			if (p == NULL)
110 				break;
111 			if (p_cansee(td, p) == 0)
112 				low = p->p_nice;
113 			PROC_UNLOCK(p);
114 		}
115 		break;
116 
117 	case PRIO_PGRP:
118 		sx_slock(&proctree_lock);
119 		if (uap->who == 0) {
120 			pg = td->td_proc->p_pgrp;
121 			PGRP_LOCK(pg);
122 		} else {
123 			pg = pgfind(uap->who);
124 			if (pg == NULL) {
125 				sx_sunlock(&proctree_lock);
126 				break;
127 			}
128 		}
129 		sx_sunlock(&proctree_lock);
130 		LIST_FOREACH(p, &pg->pg_members, p_pglist) {
131 			PROC_LOCK(p);
132 			if (p->p_state == PRS_NORMAL &&
133 			    p_cansee(td, p) == 0) {
134 				if (p->p_nice < low)
135 					low = p->p_nice;
136 			}
137 			PROC_UNLOCK(p);
138 		}
139 		PGRP_UNLOCK(pg);
140 		break;
141 
142 	case PRIO_USER:
143 		if (uap->who == 0)
144 			uap->who = td->td_ucred->cr_uid;
145 		sx_slock(&allproc_lock);
146 		FOREACH_PROC_IN_SYSTEM(p) {
147 			PROC_LOCK(p);
148 			if (p->p_state == PRS_NORMAL &&
149 			    p_cansee(td, p) == 0 &&
150 			    p->p_ucred->cr_uid == uap->who) {
151 				if (p->p_nice < low)
152 					low = p->p_nice;
153 			}
154 			PROC_UNLOCK(p);
155 		}
156 		sx_sunlock(&allproc_lock);
157 		break;
158 
159 	default:
160 		error = EINVAL;
161 		break;
162 	}
163 	if (low == PRIO_MAX + 1 && error == 0)
164 		error = ESRCH;
165 	td->td_retval[0] = low;
166 	return (error);
167 }
168 
169 #ifndef _SYS_SYSPROTO_H_
170 struct setpriority_args {
171 	int	which;
172 	int	who;
173 	int	prio;
174 };
175 #endif
176 int
177 setpriority(td, uap)
178 	struct thread *td;
179 	struct setpriority_args *uap;
180 {
181 	struct proc *curp, *p;
182 	struct pgrp *pg;
183 	int found = 0, error = 0;
184 
185 	curp = td->td_proc;
186 	switch (uap->which) {
187 	case PRIO_PROCESS:
188 		if (uap->who == 0) {
189 			PROC_LOCK(curp);
190 			error = donice(td, curp, uap->prio);
191 			PROC_UNLOCK(curp);
192 		} else {
193 			p = pfind(uap->who);
194 			if (p == NULL)
195 				break;
196 			error = p_cansee(td, p);
197 			if (error == 0)
198 				error = donice(td, p, uap->prio);
199 			PROC_UNLOCK(p);
200 		}
201 		found++;
202 		break;
203 
204 	case PRIO_PGRP:
205 		sx_slock(&proctree_lock);
206 		if (uap->who == 0) {
207 			pg = curp->p_pgrp;
208 			PGRP_LOCK(pg);
209 		} else {
210 			pg = pgfind(uap->who);
211 			if (pg == NULL) {
212 				sx_sunlock(&proctree_lock);
213 				break;
214 			}
215 		}
216 		sx_sunlock(&proctree_lock);
217 		LIST_FOREACH(p, &pg->pg_members, p_pglist) {
218 			PROC_LOCK(p);
219 			if (p->p_state == PRS_NORMAL &&
220 			    p_cansee(td, p) == 0) {
221 				error = donice(td, p, uap->prio);
222 				found++;
223 			}
224 			PROC_UNLOCK(p);
225 		}
226 		PGRP_UNLOCK(pg);
227 		break;
228 
229 	case PRIO_USER:
230 		if (uap->who == 0)
231 			uap->who = td->td_ucred->cr_uid;
232 		sx_slock(&allproc_lock);
233 		FOREACH_PROC_IN_SYSTEM(p) {
234 			PROC_LOCK(p);
235 			if (p->p_state == PRS_NORMAL &&
236 			    p->p_ucred->cr_uid == uap->who &&
237 			    p_cansee(td, p) == 0) {
238 				error = donice(td, p, uap->prio);
239 				found++;
240 			}
241 			PROC_UNLOCK(p);
242 		}
243 		sx_sunlock(&allproc_lock);
244 		break;
245 
246 	default:
247 		error = EINVAL;
248 		break;
249 	}
250 	if (found == 0 && error == 0)
251 		error = ESRCH;
252 	return (error);
253 }
254 
255 /*
256  * Set "nice" for a (whole) process.
257  */
258 static int
259 donice(struct thread *td, struct proc *p, int n)
260 {
261 	int error;
262 
263 	PROC_LOCK_ASSERT(p, MA_OWNED);
264 	if ((error = p_cansched(td, p)))
265 		return (error);
266 	if (n > PRIO_MAX)
267 		n = PRIO_MAX;
268 	if (n < PRIO_MIN)
269 		n = PRIO_MIN;
270 	if (n < p->p_nice && priv_check(td, PRIV_SCHED_SETPRIORITY) != 0)
271 		return (EACCES);
272 	sched_nice(p, n);
273 	return (0);
274 }
275 
276 /*
277  * Set realtime priority for LWP.
278  */
279 #ifndef _SYS_SYSPROTO_H_
280 struct rtprio_thread_args {
281 	int		function;
282 	lwpid_t		lwpid;
283 	struct rtprio	*rtp;
284 };
285 #endif
286 int
287 rtprio_thread(struct thread *td, struct rtprio_thread_args *uap)
288 {
289 	struct proc *p;
290 	struct rtprio rtp;
291 	struct thread *td1;
292 	int cierror, error;
293 
294 	/* Perform copyin before acquiring locks if needed. */
295 	if (uap->function == RTP_SET)
296 		cierror = copyin(uap->rtp, &rtp, sizeof(struct rtprio));
297 	else
298 		cierror = 0;
299 
300 	if (uap->lwpid == 0 || uap->lwpid == td->td_tid) {
301 		p = td->td_proc;
302 		td1 = td;
303 		PROC_LOCK(p);
304 	} else {
305 		/* Only look up thread in current process */
306 		td1 = tdfind(uap->lwpid, curproc->p_pid);
307 		if (td1 == NULL)
308 			return (ESRCH);
309 		p = td1->td_proc;
310 	}
311 
312 	switch (uap->function) {
313 	case RTP_LOOKUP:
314 		if ((error = p_cansee(td, p)))
315 			break;
316 		pri_to_rtp(td1, &rtp);
317 		PROC_UNLOCK(p);
318 		return (copyout(&rtp, uap->rtp, sizeof(struct rtprio)));
319 	case RTP_SET:
320 		if ((error = p_cansched(td, p)) || (error = cierror))
321 			break;
322 
323 		/* Disallow setting rtprio in most cases if not superuser. */
324 /*
325  * Realtime priority has to be restricted for reasons which should be
326  * obvious.  However, for idle priority, there is a potential for
327  * system deadlock if an idleprio process gains a lock on a resource
328  * that other processes need (and the idleprio process can't run
329  * due to a CPU-bound normal process).  Fix me!  XXX
330  */
331 #if 0
332 		if (RTP_PRIO_IS_REALTIME(rtp.type)) {
333 #else
334 		if (rtp.type != RTP_PRIO_NORMAL) {
335 #endif
336 			error = priv_check(td, PRIV_SCHED_RTPRIO);
337 			if (error)
338 				break;
339 		}
340 		error = rtp_to_pri(&rtp, td1);
341 		break;
342 	default:
343 		error = EINVAL;
344 		break;
345 	}
346 	PROC_UNLOCK(p);
347 	return (error);
348 }
349 
350 /*
351  * Set realtime priority.
352  */
353 #ifndef _SYS_SYSPROTO_H_
354 struct rtprio_args {
355 	int		function;
356 	pid_t		pid;
357 	struct rtprio	*rtp;
358 };
359 #endif
360 int
361 rtprio(td, uap)
362 	struct thread *td;		/* curthread */
363 	register struct rtprio_args *uap;
364 {
365 	struct proc *p;
366 	struct thread *tdp;
367 	struct rtprio rtp;
368 	int cierror, error;
369 
370 	/* Perform copyin before acquiring locks if needed. */
371 	if (uap->function == RTP_SET)
372 		cierror = copyin(uap->rtp, &rtp, sizeof(struct rtprio));
373 	else
374 		cierror = 0;
375 
376 	if (uap->pid == 0) {
377 		p = td->td_proc;
378 		PROC_LOCK(p);
379 	} else {
380 		p = pfind(uap->pid);
381 		if (p == NULL)
382 			return (ESRCH);
383 	}
384 
385 	switch (uap->function) {
386 	case RTP_LOOKUP:
387 		if ((error = p_cansee(td, p)))
388 			break;
389 		/*
390 		 * Return OUR priority if no pid specified,
391 		 * or if one is, report the highest priority
392 		 * in the process.  There isn't much more you can do as
393 		 * there is only room to return a single priority.
394 		 * Note: specifying our own pid is not the same
395 		 * as leaving it zero.
396 		 */
397 		if (uap->pid == 0) {
398 			pri_to_rtp(td, &rtp);
399 		} else {
400 			struct rtprio rtp2;
401 
402 			rtp.type = RTP_PRIO_IDLE;
403 			rtp.prio = RTP_PRIO_MAX;
404 			FOREACH_THREAD_IN_PROC(p, tdp) {
405 				pri_to_rtp(tdp, &rtp2);
406 				if (rtp2.type <  rtp.type ||
407 				    (rtp2.type == rtp.type &&
408 				    rtp2.prio < rtp.prio)) {
409 					rtp.type = rtp2.type;
410 					rtp.prio = rtp2.prio;
411 				}
412 			}
413 		}
414 		PROC_UNLOCK(p);
415 		return (copyout(&rtp, uap->rtp, sizeof(struct rtprio)));
416 	case RTP_SET:
417 		if ((error = p_cansched(td, p)) || (error = cierror))
418 			break;
419 
420 		/* Disallow setting rtprio in most cases if not superuser. */
421 /*
422  * Realtime priority has to be restricted for reasons which should be
423  * obvious.  However, for idle priority, there is a potential for
424  * system deadlock if an idleprio process gains a lock on a resource
425  * that other processes need (and the idleprio process can't run
426  * due to a CPU-bound normal process).  Fix me!  XXX
427  */
428 #if 0
429 		if (RTP_PRIO_IS_REALTIME(rtp.type)) {
430 #else
431 		if (rtp.type != RTP_PRIO_NORMAL) {
432 #endif
433 			error = priv_check(td, PRIV_SCHED_RTPRIO);
434 			if (error)
435 				break;
436 		}
437 
438 		/*
439 		 * If we are setting our own priority, set just our
440 		 * thread but if we are doing another process,
441 		 * do all the threads on that process. If we
442 		 * specify our own pid we do the latter.
443 		 */
444 		if (uap->pid == 0) {
445 			error = rtp_to_pri(&rtp, td);
446 		} else {
447 			FOREACH_THREAD_IN_PROC(p, td) {
448 				if ((error = rtp_to_pri(&rtp, td)) != 0)
449 					break;
450 			}
451 		}
452 		break;
453 	default:
454 		error = EINVAL;
455 		break;
456 	}
457 	PROC_UNLOCK(p);
458 	return (error);
459 }
460 
461 int
462 rtp_to_pri(struct rtprio *rtp, struct thread *td)
463 {
464 	u_char	newpri;
465 	u_char	oldpri;
466 
467 	switch (RTP_PRIO_BASE(rtp->type)) {
468 	case RTP_PRIO_REALTIME:
469 		if (rtp->prio > RTP_PRIO_MAX)
470 			return (EINVAL);
471 		newpri = PRI_MIN_REALTIME + rtp->prio;
472 		break;
473 	case RTP_PRIO_NORMAL:
474 		if (rtp->prio > (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE))
475 			return (EINVAL);
476 		newpri = PRI_MIN_TIMESHARE + rtp->prio;
477 		break;
478 	case RTP_PRIO_IDLE:
479 		if (rtp->prio > RTP_PRIO_MAX)
480 			return (EINVAL);
481 		newpri = PRI_MIN_IDLE + rtp->prio;
482 		break;
483 	default:
484 		return (EINVAL);
485 	}
486 
487 	thread_lock(td);
488 	sched_class(td, rtp->type);	/* XXX fix */
489 	oldpri = td->td_user_pri;
490 	sched_user_prio(td, newpri);
491 	if (curthread == td)
492 		sched_prio(curthread, td->td_user_pri); /* XXX dubious */
493 	if (TD_ON_UPILOCK(td) && oldpri != newpri) {
494 		critical_enter();
495 		thread_unlock(td);
496 		umtx_pi_adjust(td, oldpri);
497 		critical_exit();
498 	} else
499 		thread_unlock(td);
500 	return (0);
501 }
502 
503 void
504 pri_to_rtp(struct thread *td, struct rtprio *rtp)
505 {
506 
507 	thread_lock(td);
508 	switch (PRI_BASE(td->td_pri_class)) {
509 	case PRI_REALTIME:
510 		rtp->prio = td->td_base_user_pri - PRI_MIN_REALTIME;
511 		break;
512 	case PRI_TIMESHARE:
513 		rtp->prio = td->td_base_user_pri - PRI_MIN_TIMESHARE;
514 		break;
515 	case PRI_IDLE:
516 		rtp->prio = td->td_base_user_pri - PRI_MIN_IDLE;
517 		break;
518 	default:
519 		break;
520 	}
521 	rtp->type = td->td_pri_class;
522 	thread_unlock(td);
523 }
524 
525 #if defined(COMPAT_43)
526 #ifndef _SYS_SYSPROTO_H_
527 struct osetrlimit_args {
528 	u_int	which;
529 	struct	orlimit *rlp;
530 };
531 #endif
532 int
533 osetrlimit(td, uap)
534 	struct thread *td;
535 	register struct osetrlimit_args *uap;
536 {
537 	struct orlimit olim;
538 	struct rlimit lim;
539 	int error;
540 
541 	if ((error = copyin(uap->rlp, &olim, sizeof(struct orlimit))))
542 		return (error);
543 	lim.rlim_cur = olim.rlim_cur;
544 	lim.rlim_max = olim.rlim_max;
545 	error = kern_setrlimit(td, uap->which, &lim);
546 	return (error);
547 }
548 
549 #ifndef _SYS_SYSPROTO_H_
550 struct ogetrlimit_args {
551 	u_int	which;
552 	struct	orlimit *rlp;
553 };
554 #endif
555 int
556 ogetrlimit(td, uap)
557 	struct thread *td;
558 	register struct ogetrlimit_args *uap;
559 {
560 	struct orlimit olim;
561 	struct rlimit rl;
562 	struct proc *p;
563 	int error;
564 
565 	if (uap->which >= RLIM_NLIMITS)
566 		return (EINVAL);
567 	p = td->td_proc;
568 	PROC_LOCK(p);
569 	lim_rlimit(p, uap->which, &rl);
570 	PROC_UNLOCK(p);
571 
572 	/*
573 	 * XXX would be more correct to convert only RLIM_INFINITY to the
574 	 * old RLIM_INFINITY and fail with EOVERFLOW for other larger
575 	 * values.  Most 64->32 and 32->16 conversions, including not
576 	 * unimportant ones of uids are even more broken than what we
577 	 * do here (they blindly truncate).  We don't do this correctly
578 	 * here since we have little experience with EOVERFLOW yet.
579 	 * Elsewhere, getuid() can't fail...
580 	 */
581 	olim.rlim_cur = rl.rlim_cur > 0x7fffffff ? 0x7fffffff : rl.rlim_cur;
582 	olim.rlim_max = rl.rlim_max > 0x7fffffff ? 0x7fffffff : rl.rlim_max;
583 	error = copyout(&olim, uap->rlp, sizeof(olim));
584 	return (error);
585 }
586 #endif /* COMPAT_43 */
587 
588 #ifndef _SYS_SYSPROTO_H_
589 struct __setrlimit_args {
590 	u_int	which;
591 	struct	rlimit *rlp;
592 };
593 #endif
594 int
595 setrlimit(td, uap)
596 	struct thread *td;
597 	register struct __setrlimit_args *uap;
598 {
599 	struct rlimit alim;
600 	int error;
601 
602 	if ((error = copyin(uap->rlp, &alim, sizeof(struct rlimit))))
603 		return (error);
604 	error = kern_setrlimit(td, uap->which, &alim);
605 	return (error);
606 }
607 
608 static void
609 lim_cb(void *arg)
610 {
611 	struct rlimit rlim;
612 	struct thread *td;
613 	struct proc *p;
614 
615 	p = arg;
616 	PROC_LOCK_ASSERT(p, MA_OWNED);
617 	/*
618 	 * Check if the process exceeds its cpu resource allocation.  If
619 	 * it reaches the max, arrange to kill the process in ast().
620 	 */
621 	if (p->p_cpulimit == RLIM_INFINITY)
622 		return;
623 	PROC_SLOCK(p);
624 	FOREACH_THREAD_IN_PROC(p, td) {
625 		ruxagg(p, td);
626 	}
627 	PROC_SUNLOCK(p);
628 	if (p->p_rux.rux_runtime > p->p_cpulimit * cpu_tickrate()) {
629 		lim_rlimit(p, RLIMIT_CPU, &rlim);
630 		if (p->p_rux.rux_runtime >= rlim.rlim_max * cpu_tickrate()) {
631 			killproc(p, "exceeded maximum CPU limit");
632 		} else {
633 			if (p->p_cpulimit < rlim.rlim_max)
634 				p->p_cpulimit += 5;
635 			psignal(p, SIGXCPU);
636 		}
637 	}
638 	if ((p->p_flag & P_WEXIT) == 0)
639 		callout_reset(&p->p_limco, hz, lim_cb, p);
640 }
641 
642 int
643 kern_setrlimit(td, which, limp)
644 	struct thread *td;
645 	u_int which;
646 	struct rlimit *limp;
647 {
648 	struct plimit *newlim, *oldlim;
649 	struct proc *p;
650 	register struct rlimit *alimp;
651 	struct rlimit oldssiz;
652 	int error;
653 
654 	if (which >= RLIM_NLIMITS)
655 		return (EINVAL);
656 
657 	/*
658 	 * Preserve historical bugs by treating negative limits as unsigned.
659 	 */
660 	if (limp->rlim_cur < 0)
661 		limp->rlim_cur = RLIM_INFINITY;
662 	if (limp->rlim_max < 0)
663 		limp->rlim_max = RLIM_INFINITY;
664 
665 	oldssiz.rlim_cur = 0;
666 	p = td->td_proc;
667 	newlim = lim_alloc();
668 	PROC_LOCK(p);
669 	oldlim = p->p_limit;
670 	alimp = &oldlim->pl_rlimit[which];
671 	if (limp->rlim_cur > alimp->rlim_max ||
672 	    limp->rlim_max > alimp->rlim_max)
673 		if ((error = priv_check(td, PRIV_PROC_SETRLIMIT))) {
674 			PROC_UNLOCK(p);
675 			lim_free(newlim);
676 			return (error);
677 		}
678 	if (limp->rlim_cur > limp->rlim_max)
679 		limp->rlim_cur = limp->rlim_max;
680 	lim_copy(newlim, oldlim);
681 	alimp = &newlim->pl_rlimit[which];
682 
683 	switch (which) {
684 
685 	case RLIMIT_CPU:
686 		if (limp->rlim_cur != RLIM_INFINITY &&
687 		    p->p_cpulimit == RLIM_INFINITY)
688 			callout_reset(&p->p_limco, hz, lim_cb, p);
689 		p->p_cpulimit = limp->rlim_cur;
690 		break;
691 	case RLIMIT_DATA:
692 		if (limp->rlim_cur > maxdsiz)
693 			limp->rlim_cur = maxdsiz;
694 		if (limp->rlim_max > maxdsiz)
695 			limp->rlim_max = maxdsiz;
696 		break;
697 
698 	case RLIMIT_STACK:
699 		if (limp->rlim_cur > maxssiz)
700 			limp->rlim_cur = maxssiz;
701 		if (limp->rlim_max > maxssiz)
702 			limp->rlim_max = maxssiz;
703 		oldssiz = *alimp;
704 		if (p->p_sysent->sv_fixlimit != NULL)
705 			p->p_sysent->sv_fixlimit(&oldssiz,
706 			    RLIMIT_STACK);
707 		break;
708 
709 	case RLIMIT_NOFILE:
710 		if (limp->rlim_cur > maxfilesperproc)
711 			limp->rlim_cur = maxfilesperproc;
712 		if (limp->rlim_max > maxfilesperproc)
713 			limp->rlim_max = maxfilesperproc;
714 		break;
715 
716 	case RLIMIT_NPROC:
717 		if (limp->rlim_cur > maxprocperuid)
718 			limp->rlim_cur = maxprocperuid;
719 		if (limp->rlim_max > maxprocperuid)
720 			limp->rlim_max = maxprocperuid;
721 		if (limp->rlim_cur < 1)
722 			limp->rlim_cur = 1;
723 		if (limp->rlim_max < 1)
724 			limp->rlim_max = 1;
725 		break;
726 	}
727 	if (p->p_sysent->sv_fixlimit != NULL)
728 		p->p_sysent->sv_fixlimit(limp, which);
729 	*alimp = *limp;
730 	p->p_limit = newlim;
731 	PROC_UNLOCK(p);
732 	lim_free(oldlim);
733 
734 	if (which == RLIMIT_STACK) {
735 		/*
736 		 * Stack is allocated to the max at exec time with only
737 		 * "rlim_cur" bytes accessible.  If stack limit is going
738 		 * up make more accessible, if going down make inaccessible.
739 		 */
740 		if (limp->rlim_cur != oldssiz.rlim_cur) {
741 			vm_offset_t addr;
742 			vm_size_t size;
743 			vm_prot_t prot;
744 
745 			if (limp->rlim_cur > oldssiz.rlim_cur) {
746 				prot = p->p_sysent->sv_stackprot;
747 				size = limp->rlim_cur - oldssiz.rlim_cur;
748 				addr = p->p_sysent->sv_usrstack -
749 				    limp->rlim_cur;
750 			} else {
751 				prot = VM_PROT_NONE;
752 				size = oldssiz.rlim_cur - limp->rlim_cur;
753 				addr = p->p_sysent->sv_usrstack -
754 				    oldssiz.rlim_cur;
755 			}
756 			addr = trunc_page(addr);
757 			size = round_page(size);
758 			(void)vm_map_protect(&p->p_vmspace->vm_map,
759 			    addr, addr + size, prot, FALSE);
760 		}
761 	}
762 
763 	return (0);
764 }
765 
766 #ifndef _SYS_SYSPROTO_H_
767 struct __getrlimit_args {
768 	u_int	which;
769 	struct	rlimit *rlp;
770 };
771 #endif
772 /* ARGSUSED */
773 int
774 getrlimit(td, uap)
775 	struct thread *td;
776 	register struct __getrlimit_args *uap;
777 {
778 	struct rlimit rlim;
779 	struct proc *p;
780 	int error;
781 
782 	if (uap->which >= RLIM_NLIMITS)
783 		return (EINVAL);
784 	p = td->td_proc;
785 	PROC_LOCK(p);
786 	lim_rlimit(p, uap->which, &rlim);
787 	PROC_UNLOCK(p);
788 	error = copyout(&rlim, uap->rlp, sizeof(struct rlimit));
789 	return (error);
790 }
791 
792 /*
793  * Transform the running time and tick information for children of proc p
794  * into user and system time usage.
795  */
796 void
797 calccru(p, up, sp)
798 	struct proc *p;
799 	struct timeval *up;
800 	struct timeval *sp;
801 {
802 
803 	PROC_LOCK_ASSERT(p, MA_OWNED);
804 	calcru1(p, &p->p_crux, up, sp);
805 }
806 
807 /*
808  * Transform the running time and tick information in proc p into user
809  * and system time usage.  If appropriate, include the current time slice
810  * on this CPU.
811  */
812 void
813 calcru(struct proc *p, struct timeval *up, struct timeval *sp)
814 {
815 	struct thread *td;
816 	uint64_t u;
817 
818 	PROC_LOCK_ASSERT(p, MA_OWNED);
819 	PROC_SLOCK_ASSERT(p, MA_OWNED);
820 	/*
821 	 * If we are getting stats for the current process, then add in the
822 	 * stats that this thread has accumulated in its current time slice.
823 	 * We reset the thread and CPU state as if we had performed a context
824 	 * switch right here.
825 	 */
826 	td = curthread;
827 	if (td->td_proc == p) {
828 		u = cpu_ticks();
829 		p->p_rux.rux_runtime += u - PCPU_GET(switchtime);
830 		PCPU_SET(switchtime, u);
831 	}
832 	/* Make sure the per-thread stats are current. */
833 	FOREACH_THREAD_IN_PROC(p, td) {
834 		if (td->td_incruntime == 0)
835 			continue;
836 		ruxagg(p, td);
837 	}
838 	calcru1(p, &p->p_rux, up, sp);
839 }
840 
841 static void
842 calcru1(struct proc *p, struct rusage_ext *ruxp, struct timeval *up,
843     struct timeval *sp)
844 {
845 	/* {user, system, interrupt, total} {ticks, usec}: */
846 	uint64_t ut, uu, st, su, it, tt, tu;
847 
848 	ut = ruxp->rux_uticks;
849 	st = ruxp->rux_sticks;
850 	it = ruxp->rux_iticks;
851 	tt = ut + st + it;
852 	if (tt == 0) {
853 		/* Avoid divide by zero */
854 		st = 1;
855 		tt = 1;
856 	}
857 	tu = cputick2usec(ruxp->rux_runtime);
858 	if ((int64_t)tu < 0) {
859 		/* XXX: this should be an assert /phk */
860 		printf("calcru: negative runtime of %jd usec for pid %d (%s)\n",
861 		    (intmax_t)tu, p->p_pid, p->p_comm);
862 		tu = ruxp->rux_tu;
863 	}
864 
865 	if (tu >= ruxp->rux_tu) {
866 		/*
867 		 * The normal case, time increased.
868 		 * Enforce monotonicity of bucketed numbers.
869 		 */
870 		uu = (tu * ut) / tt;
871 		if (uu < ruxp->rux_uu)
872 			uu = ruxp->rux_uu;
873 		su = (tu * st) / tt;
874 		if (su < ruxp->rux_su)
875 			su = ruxp->rux_su;
876 	} else if (tu + 3 > ruxp->rux_tu || 101 * tu > 100 * ruxp->rux_tu) {
877 		/*
878 		 * When we calibrate the cputicker, it is not uncommon to
879 		 * see the presumably fixed frequency increase slightly over
880 		 * time as a result of thermal stabilization and NTP
881 		 * discipline (of the reference clock).  We therefore ignore
882 		 * a bit of backwards slop because we  expect to catch up
883 		 * shortly.  We use a 3 microsecond limit to catch low
884 		 * counts and a 1% limit for high counts.
885 		 */
886 		uu = ruxp->rux_uu;
887 		su = ruxp->rux_su;
888 		tu = ruxp->rux_tu;
889 	} else { /* tu < ruxp->rux_tu */
890 		/*
891 		 * What happened here was likely that a laptop, which ran at
892 		 * a reduced clock frequency at boot, kicked into high gear.
893 		 * The wisdom of spamming this message in that case is
894 		 * dubious, but it might also be indicative of something
895 		 * serious, so lets keep it and hope laptops can be made
896 		 * more truthful about their CPU speed via ACPI.
897 		 */
898 		printf("calcru: runtime went backwards from %ju usec "
899 		    "to %ju usec for pid %d (%s)\n",
900 		    (uintmax_t)ruxp->rux_tu, (uintmax_t)tu,
901 		    p->p_pid, p->p_comm);
902 		uu = (tu * ut) / tt;
903 		su = (tu * st) / tt;
904 	}
905 
906 	ruxp->rux_uu = uu;
907 	ruxp->rux_su = su;
908 	ruxp->rux_tu = tu;
909 
910 	up->tv_sec = uu / 1000000;
911 	up->tv_usec = uu % 1000000;
912 	sp->tv_sec = su / 1000000;
913 	sp->tv_usec = su % 1000000;
914 }
915 
916 #ifndef _SYS_SYSPROTO_H_
917 struct getrusage_args {
918 	int	who;
919 	struct	rusage *rusage;
920 };
921 #endif
922 int
923 getrusage(td, uap)
924 	register struct thread *td;
925 	register struct getrusage_args *uap;
926 {
927 	struct rusage ru;
928 	int error;
929 
930 	error = kern_getrusage(td, uap->who, &ru);
931 	if (error == 0)
932 		error = copyout(&ru, uap->rusage, sizeof(struct rusage));
933 	return (error);
934 }
935 
936 int
937 kern_getrusage(struct thread *td, int who, struct rusage *rup)
938 {
939 	struct proc *p;
940 	int error;
941 
942 	error = 0;
943 	p = td->td_proc;
944 	PROC_LOCK(p);
945 	switch (who) {
946 	case RUSAGE_SELF:
947 		rufetchcalc(p, rup, &rup->ru_utime,
948 		    &rup->ru_stime);
949 		break;
950 
951 	case RUSAGE_CHILDREN:
952 		*rup = p->p_stats->p_cru;
953 		calccru(p, &rup->ru_utime, &rup->ru_stime);
954 		break;
955 
956 	case RUSAGE_THREAD:
957 		PROC_SLOCK(p);
958 		ruxagg(p, td);
959 		PROC_SUNLOCK(p);
960 		thread_lock(td);
961 		*rup = td->td_ru;
962 		calcru1(p, &td->td_rux, &rup->ru_utime, &rup->ru_stime);
963 		thread_unlock(td);
964 		break;
965 
966 	default:
967 		error = EINVAL;
968 	}
969 	PROC_UNLOCK(p);
970 	return (error);
971 }
972 
973 void
974 rucollect(struct rusage *ru, struct rusage *ru2)
975 {
976 	long *ip, *ip2;
977 	int i;
978 
979 	if (ru->ru_maxrss < ru2->ru_maxrss)
980 		ru->ru_maxrss = ru2->ru_maxrss;
981 	ip = &ru->ru_first;
982 	ip2 = &ru2->ru_first;
983 	for (i = &ru->ru_last - &ru->ru_first; i >= 0; i--)
984 		*ip++ += *ip2++;
985 }
986 
987 void
988 ruadd(struct rusage *ru, struct rusage_ext *rux, struct rusage *ru2,
989     struct rusage_ext *rux2)
990 {
991 
992 	rux->rux_runtime += rux2->rux_runtime;
993 	rux->rux_uticks += rux2->rux_uticks;
994 	rux->rux_sticks += rux2->rux_sticks;
995 	rux->rux_iticks += rux2->rux_iticks;
996 	rux->rux_uu += rux2->rux_uu;
997 	rux->rux_su += rux2->rux_su;
998 	rux->rux_tu += rux2->rux_tu;
999 	rucollect(ru, ru2);
1000 }
1001 
1002 /*
1003  * Aggregate tick counts into the proc's rusage_ext.
1004  */
1005 static void
1006 ruxagg_locked(struct rusage_ext *rux, struct thread *td)
1007 {
1008 
1009 	THREAD_LOCK_ASSERT(td, MA_OWNED);
1010 	PROC_SLOCK_ASSERT(td->td_proc, MA_OWNED);
1011 	rux->rux_runtime += td->td_incruntime;
1012 	rux->rux_uticks += td->td_uticks;
1013 	rux->rux_sticks += td->td_sticks;
1014 	rux->rux_iticks += td->td_iticks;
1015 }
1016 
1017 void
1018 ruxagg(struct proc *p, struct thread *td)
1019 {
1020 
1021 	thread_lock(td);
1022 	ruxagg_locked(&p->p_rux, td);
1023 	ruxagg_locked(&td->td_rux, td);
1024 	td->td_incruntime = 0;
1025 	td->td_uticks = 0;
1026 	td->td_iticks = 0;
1027 	td->td_sticks = 0;
1028 	thread_unlock(td);
1029 }
1030 
1031 /*
1032  * Update the rusage_ext structure and fetch a valid aggregate rusage
1033  * for proc p if storage for one is supplied.
1034  */
1035 void
1036 rufetch(struct proc *p, struct rusage *ru)
1037 {
1038 	struct thread *td;
1039 
1040 	PROC_SLOCK_ASSERT(p, MA_OWNED);
1041 
1042 	*ru = p->p_ru;
1043 	if (p->p_numthreads > 0)  {
1044 		FOREACH_THREAD_IN_PROC(p, td) {
1045 			ruxagg(p, td);
1046 			rucollect(ru, &td->td_ru);
1047 		}
1048 	}
1049 }
1050 
1051 /*
1052  * Atomically perform a rufetch and a calcru together.
1053  * Consumers, can safely assume the calcru is executed only once
1054  * rufetch is completed.
1055  */
1056 void
1057 rufetchcalc(struct proc *p, struct rusage *ru, struct timeval *up,
1058     struct timeval *sp)
1059 {
1060 
1061 	PROC_SLOCK(p);
1062 	rufetch(p, ru);
1063 	calcru(p, up, sp);
1064 	PROC_SUNLOCK(p);
1065 }
1066 
1067 /*
1068  * Allocate a new resource limits structure and initialize its
1069  * reference count and mutex pointer.
1070  */
1071 struct plimit *
1072 lim_alloc()
1073 {
1074 	struct plimit *limp;
1075 
1076 	limp = malloc(sizeof(struct plimit), M_PLIMIT, M_WAITOK);
1077 	refcount_init(&limp->pl_refcnt, 1);
1078 	return (limp);
1079 }
1080 
1081 struct plimit *
1082 lim_hold(limp)
1083 	struct plimit *limp;
1084 {
1085 
1086 	refcount_acquire(&limp->pl_refcnt);
1087 	return (limp);
1088 }
1089 
1090 void
1091 lim_fork(struct proc *p1, struct proc *p2)
1092 {
1093 	p2->p_limit = lim_hold(p1->p_limit);
1094 	callout_init_mtx(&p2->p_limco, &p2->p_mtx, 0);
1095 	if (p1->p_cpulimit != RLIM_INFINITY)
1096 		callout_reset(&p2->p_limco, hz, lim_cb, p2);
1097 }
1098 
1099 void
1100 lim_free(limp)
1101 	struct plimit *limp;
1102 {
1103 
1104 	KASSERT(limp->pl_refcnt > 0, ("plimit refcnt underflow"));
1105 	if (refcount_release(&limp->pl_refcnt))
1106 		free((void *)limp, M_PLIMIT);
1107 }
1108 
1109 /*
1110  * Make a copy of the plimit structure.
1111  * We share these structures copy-on-write after fork.
1112  */
1113 void
1114 lim_copy(dst, src)
1115 	struct plimit *dst, *src;
1116 {
1117 
1118 	KASSERT(dst->pl_refcnt == 1, ("lim_copy to shared limit"));
1119 	bcopy(src->pl_rlimit, dst->pl_rlimit, sizeof(src->pl_rlimit));
1120 }
1121 
1122 /*
1123  * Return the hard limit for a particular system resource.  The
1124  * which parameter specifies the index into the rlimit array.
1125  */
1126 rlim_t
1127 lim_max(struct proc *p, int which)
1128 {
1129 	struct rlimit rl;
1130 
1131 	lim_rlimit(p, which, &rl);
1132 	return (rl.rlim_max);
1133 }
1134 
1135 /*
1136  * Return the current (soft) limit for a particular system resource.
1137  * The which parameter which specifies the index into the rlimit array
1138  */
1139 rlim_t
1140 lim_cur(struct proc *p, int which)
1141 {
1142 	struct rlimit rl;
1143 
1144 	lim_rlimit(p, which, &rl);
1145 	return (rl.rlim_cur);
1146 }
1147 
1148 /*
1149  * Return a copy of the entire rlimit structure for the system limit
1150  * specified by 'which' in the rlimit structure pointed to by 'rlp'.
1151  */
1152 void
1153 lim_rlimit(struct proc *p, int which, struct rlimit *rlp)
1154 {
1155 
1156 	PROC_LOCK_ASSERT(p, MA_OWNED);
1157 	KASSERT(which >= 0 && which < RLIM_NLIMITS,
1158 	    ("request for invalid resource limit"));
1159 	*rlp = p->p_limit->pl_rlimit[which];
1160 	if (p->p_sysent->sv_fixlimit != NULL)
1161 		p->p_sysent->sv_fixlimit(rlp, which);
1162 }
1163 
1164 void
1165 uihashinit()
1166 {
1167 
1168 	uihashtbl = hashinit(maxproc / 16, M_UIDINFO, &uihash);
1169 	rw_init(&uihashtbl_lock, "uidinfo hash");
1170 }
1171 
1172 /*
1173  * Look up a uidinfo struct for the parameter uid.
1174  * uihashtbl_lock must be locked.
1175  */
1176 static struct uidinfo *
1177 uilookup(uid)
1178 	uid_t uid;
1179 {
1180 	struct uihashhead *uipp;
1181 	struct uidinfo *uip;
1182 
1183 	rw_assert(&uihashtbl_lock, RA_LOCKED);
1184 	uipp = UIHASH(uid);
1185 	LIST_FOREACH(uip, uipp, ui_hash)
1186 		if (uip->ui_uid == uid)
1187 			break;
1188 
1189 	return (uip);
1190 }
1191 
1192 /*
1193  * Find or allocate a struct uidinfo for a particular uid.
1194  * Increase refcount on uidinfo struct returned.
1195  * uifree() should be called on a struct uidinfo when released.
1196  */
1197 struct uidinfo *
1198 uifind(uid)
1199 	uid_t uid;
1200 {
1201 	struct uidinfo *old_uip, *uip;
1202 
1203 	rw_rlock(&uihashtbl_lock);
1204 	uip = uilookup(uid);
1205 	if (uip == NULL) {
1206 		rw_runlock(&uihashtbl_lock);
1207 		uip = malloc(sizeof(*uip), M_UIDINFO, M_WAITOK | M_ZERO);
1208 		racct_create(&uip->ui_racct);
1209 		rw_wlock(&uihashtbl_lock);
1210 		/*
1211 		 * There's a chance someone created our uidinfo while we
1212 		 * were in malloc and not holding the lock, so we have to
1213 		 * make sure we don't insert a duplicate uidinfo.
1214 		 */
1215 		if ((old_uip = uilookup(uid)) != NULL) {
1216 			/* Someone else beat us to it. */
1217 			racct_destroy(&uip->ui_racct);
1218 			free(uip, M_UIDINFO);
1219 			uip = old_uip;
1220 		} else {
1221 			refcount_init(&uip->ui_ref, 0);
1222 			uip->ui_uid = uid;
1223 			mtx_init(&uip->ui_vmsize_mtx, "ui_vmsize", NULL,
1224 			    MTX_DEF);
1225 			LIST_INSERT_HEAD(UIHASH(uid), uip, ui_hash);
1226 		}
1227 	}
1228 	uihold(uip);
1229 	rw_unlock(&uihashtbl_lock);
1230 	return (uip);
1231 }
1232 
1233 /*
1234  * Place another refcount on a uidinfo struct.
1235  */
1236 void
1237 uihold(uip)
1238 	struct uidinfo *uip;
1239 {
1240 
1241 	refcount_acquire(&uip->ui_ref);
1242 }
1243 
1244 /*-
1245  * Since uidinfo structs have a long lifetime, we use an
1246  * opportunistic refcounting scheme to avoid locking the lookup hash
1247  * for each release.
1248  *
1249  * If the refcount hits 0, we need to free the structure,
1250  * which means we need to lock the hash.
1251  * Optimal case:
1252  *   After locking the struct and lowering the refcount, if we find
1253  *   that we don't need to free, simply unlock and return.
1254  * Suboptimal case:
1255  *   If refcount lowering results in need to free, bump the count
1256  *   back up, lose the lock and acquire the locks in the proper
1257  *   order to try again.
1258  */
1259 void
1260 uifree(uip)
1261 	struct uidinfo *uip;
1262 {
1263 	int old;
1264 
1265 	/* Prepare for optimal case. */
1266 	old = uip->ui_ref;
1267 	if (old > 1 && atomic_cmpset_int(&uip->ui_ref, old, old - 1))
1268 		return;
1269 
1270 	/* Prepare for suboptimal case. */
1271 	rw_wlock(&uihashtbl_lock);
1272 	if (refcount_release(&uip->ui_ref)) {
1273 		racct_destroy(&uip->ui_racct);
1274 		LIST_REMOVE(uip, ui_hash);
1275 		rw_wunlock(&uihashtbl_lock);
1276 		if (uip->ui_sbsize != 0)
1277 			printf("freeing uidinfo: uid = %d, sbsize = %ld\n",
1278 			    uip->ui_uid, uip->ui_sbsize);
1279 		if (uip->ui_proccnt != 0)
1280 			printf("freeing uidinfo: uid = %d, proccnt = %ld\n",
1281 			    uip->ui_uid, uip->ui_proccnt);
1282 		if (uip->ui_vmsize != 0)
1283 			printf("freeing uidinfo: uid = %d, swapuse = %lld\n",
1284 			    uip->ui_uid, (unsigned long long)uip->ui_vmsize);
1285 		mtx_destroy(&uip->ui_vmsize_mtx);
1286 		free(uip, M_UIDINFO);
1287 		return;
1288 	}
1289 	/*
1290 	 * Someone added a reference between atomic_cmpset_int() and
1291 	 * rw_wlock(&uihashtbl_lock).
1292 	 */
1293 	rw_wunlock(&uihashtbl_lock);
1294 }
1295 
1296 void
1297 ui_racct_foreach(void (*callback)(struct racct *racct,
1298     void *arg2, void *arg3), void *arg2, void *arg3)
1299 {
1300 	struct uidinfo *uip;
1301 	struct uihashhead *uih;
1302 
1303 	rw_rlock(&uihashtbl_lock);
1304 	for (uih = &uihashtbl[uihash]; uih >= uihashtbl; uih--) {
1305 		LIST_FOREACH(uip, uih, ui_hash) {
1306 			(callback)(uip->ui_racct, arg2, arg3);
1307 		}
1308 	}
1309 	rw_runlock(&uihashtbl_lock);
1310 }
1311 
1312 /*
1313  * Change the count associated with number of processes
1314  * a given user is using.  When 'max' is 0, don't enforce a limit
1315  */
1316 int
1317 chgproccnt(uip, diff, max)
1318 	struct	uidinfo	*uip;
1319 	int	diff;
1320 	rlim_t	max;
1321 {
1322 
1323 	/* Don't allow them to exceed max, but allow subtraction. */
1324 	if (diff > 0 && max != 0) {
1325 		if (atomic_fetchadd_long(&uip->ui_proccnt, (long)diff) + diff > max) {
1326 			atomic_subtract_long(&uip->ui_proccnt, (long)diff);
1327 			return (0);
1328 		}
1329 	} else {
1330 		atomic_add_long(&uip->ui_proccnt, (long)diff);
1331 		if (uip->ui_proccnt < 0)
1332 			printf("negative proccnt for uid = %d\n", uip->ui_uid);
1333 	}
1334 	return (1);
1335 }
1336 
1337 /*
1338  * Change the total socket buffer size a user has used.
1339  */
1340 int
1341 chgsbsize(uip, hiwat, to, max)
1342 	struct	uidinfo	*uip;
1343 	u_int  *hiwat;
1344 	u_int	to;
1345 	rlim_t	max;
1346 {
1347 	int diff;
1348 
1349 	diff = to - *hiwat;
1350 	if (diff > 0) {
1351 		if (atomic_fetchadd_long(&uip->ui_sbsize, (long)diff) + diff > max) {
1352 			atomic_subtract_long(&uip->ui_sbsize, (long)diff);
1353 			return (0);
1354 		}
1355 	} else {
1356 		atomic_add_long(&uip->ui_sbsize, (long)diff);
1357 		if (uip->ui_sbsize < 0)
1358 			printf("negative sbsize for uid = %d\n", uip->ui_uid);
1359 	}
1360 	*hiwat = to;
1361 	return (1);
1362 }
1363 
1364 /*
1365  * Change the count associated with number of pseudo-terminals
1366  * a given user is using.  When 'max' is 0, don't enforce a limit
1367  */
1368 int
1369 chgptscnt(uip, diff, max)
1370 	struct	uidinfo	*uip;
1371 	int	diff;
1372 	rlim_t	max;
1373 {
1374 
1375 	/* Don't allow them to exceed max, but allow subtraction. */
1376 	if (diff > 0 && max != 0) {
1377 		if (atomic_fetchadd_long(&uip->ui_ptscnt, (long)diff) + diff > max) {
1378 			atomic_subtract_long(&uip->ui_ptscnt, (long)diff);
1379 			return (0);
1380 		}
1381 	} else {
1382 		atomic_add_long(&uip->ui_ptscnt, (long)diff);
1383 		if (uip->ui_ptscnt < 0)
1384 			printf("negative ptscnt for uid = %d\n", uip->ui_uid);
1385 	}
1386 	return (1);
1387 }
1388