xref: /titanic_50/usr/src/uts/common/os/pid.c (revision 2020b2b6df0384feda1732f65486c4604fbf5bea)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright (c) 1989, 2010, Oracle and/or its affiliates. All rights reserved.
24  */
25 
26 /*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
27 /*	  All Rights Reserved  	*/
28 
29 #include <sys/types.h>
30 #include <sys/param.h>
31 #include <sys/sysmacros.h>
32 #include <sys/proc.h>
33 #include <sys/kmem.h>
34 #include <sys/tuneable.h>
35 #include <sys/var.h>
36 #include <sys/cred.h>
37 #include <sys/systm.h>
38 #include <sys/prsystm.h>
39 #include <sys/vnode.h>
40 #include <sys/session.h>
41 #include <sys/cpuvar.h>
42 #include <sys/cmn_err.h>
43 #include <sys/bitmap.h>
44 #include <sys/debug.h>
45 #include <c2/audit.h>
46 #include <sys/project.h>
47 #include <sys/task.h>
48 #include <sys/zone.h>
49 
50 /* directory entries for /proc */
51 union procent {
52 	proc_t *pe_proc;
53 	union procent *pe_next;
54 };
55 
56 struct pid pid0 = {
57 	0,		/* pid_prinactive */
58 	1,		/* pid_pgorphaned */
59 	0,		/* pid_padding	*/
60 	0,		/* pid_prslot	*/
61 	0,		/* pid_id	*/
62 	NULL,		/* pid_pglink	*/
63 	NULL,		/* pid_pgtail	*/
64 	NULL,		/* pid_link	*/
65 	3		/* pid_ref	*/
66 };
67 
68 static int pid_hashlen = 4;	/* desired average hash chain length */
69 static int pid_hashsz;		/* number of buckets in the hash table */
70 
71 #define	HASHPID(pid)	(pidhash[((pid)&(pid_hashsz-1))])
72 
73 extern uint_t nproc;
74 extern struct kmem_cache *process_cache;
75 static void	upcount_init(void);
76 
77 kmutex_t	pidlock;	/* global process lock */
78 kmutex_t	pr_pidlock;	/* /proc global process lock */
79 kcondvar_t	*pr_pid_cv;	/* for /proc, one per process slot */
80 struct plock	*proc_lock;	/* persistent array of p_lock's */
81 
82 /*
83  * See the comment above pid_getlockslot() for a detailed explanation of this
84  * constant.  Note that a PLOCK_SHIFT of 3 implies 64-byte coherence
85  * granularity; if the coherence granularity is ever changed, this constant
86  * should be modified to reflect the change to minimize proc_lock false
87  * sharing (correctness, however, is guaranteed regardless of the coherence
88  * granularity).
89  */
90 #define	PLOCK_SHIFT	3
91 
92 static kmutex_t	pidlinklock;
93 static struct pid **pidhash;
94 static pid_t minpid;
95 static pid_t mpid = FAMOUS_PIDS;	/* one more than the last famous pid */
96 static union procent *procdir;
97 static union procent *procentfree;
98 
99 static struct pid *
100 pid_lookup(pid_t pid)
101 {
102 	struct pid *pidp;
103 
104 	ASSERT(MUTEX_HELD(&pidlinklock));
105 
106 	for (pidp = HASHPID(pid); pidp; pidp = pidp->pid_link) {
107 		if (pidp->pid_id == pid) {
108 			ASSERT(pidp->pid_ref > 0);
109 			break;
110 		}
111 	}
112 	return (pidp);
113 }
114 
115 void
116 pid_setmin(void)
117 {
118 	if (jump_pid && jump_pid > mpid)
119 		minpid = mpid = jump_pid;
120 	else
121 		minpid = mpid;
122 }
123 
124 /*
125  * When prslots are simply used as an index to determine a process' p_lock,
126  * adjacent prslots share adjacent p_locks.  On machines where the size
127  * of a mutex is smaller than that of a cache line (which, as of this writing,
128  * is true for all machines on which Solaris runs), this can potentially
129  * induce false sharing.  The standard solution for false sharing is to pad
130  * out one's data structures (in this case, struct plock).  However,
131  * given the size and (generally) sparse use of the proc_lock array, this
132  * is suboptimal.  We therefore stride through the proc_lock array with
133  * a stride of PLOCK_SHIFT.  PLOCK_SHIFT should be defined as:
134  *
135  *   log_2 (coherence_granularity / sizeof (kmutex_t))
136  *
137  * Under this scheme, false sharing is still possible -- but only when
138  * the number of active processes is very large.  Note that the one-to-one
139  * mapping between prslots and lockslots is maintained.
140  */
141 static int
142 pid_getlockslot(int prslot)
143 {
144 	int even = (v.v_proc >> PLOCK_SHIFT) << PLOCK_SHIFT;
145 	int perlap = even >> PLOCK_SHIFT;
146 
147 	if (prslot >= even)
148 		return (prslot);
149 
150 	return (((prslot % perlap) << PLOCK_SHIFT) + (prslot / perlap));
151 }
152 
153 /*
154  * This function allocates a pid structure, a free pid, and optionally a
155  * slot in the proc table for it.
156  *
157  * pid_allocate() returns the new pid on success, -1 on failure.
158  */
159 pid_t
160 pid_allocate(proc_t *prp, pid_t pid, int flags)
161 {
162 	struct pid *pidp;
163 	union procent *pep;
164 	pid_t newpid, startpid;
165 
166 	pidp = kmem_zalloc(sizeof (struct pid), KM_SLEEP);
167 
168 	mutex_enter(&pidlinklock);
169 	if ((flags & PID_ALLOC_PROC) && (pep = procentfree) == NULL) {
170 		/*
171 		 * ran out of /proc directory entries
172 		 */
173 		goto failed;
174 	}
175 
176 	if (pid != 0) {
177 		VERIFY(minpid == 0);
178 		VERIFY3P(pid, <, mpid);
179 		VERIFY3P(pid_lookup(pid), ==, NULL);
180 		newpid = pid;
181 	} else {
182 		/*
183 		 * Allocate a pid
184 		 */
185 		ASSERT(minpid <= mpid && mpid < maxpid);
186 
187 		startpid = mpid;
188 		for (;;) {
189 			newpid = mpid;
190 			if (++mpid == maxpid)
191 				mpid = minpid;
192 
193 			if (pid_lookup(newpid) == NULL)
194 				break;
195 
196 			if (mpid == startpid)
197 				goto failed;
198 		}
199 	}
200 
201 	/*
202 	 * Put pid into the pid hash table.
203 	 */
204 	pidp->pid_link = HASHPID(newpid);
205 	HASHPID(newpid) = pidp;
206 	pidp->pid_ref = 1;
207 	pidp->pid_id = newpid;
208 
209 	if (flags & PID_ALLOC_PROC) {
210 		procentfree = pep->pe_next;
211 		pidp->pid_prslot = pep - procdir;
212 		pep->pe_proc = prp;
213 		prp->p_pidp = pidp;
214 		prp->p_lockp = &proc_lock[pid_getlockslot(pidp->pid_prslot)];
215 	} else {
216 		pidp->pid_prslot = 0;
217 	}
218 
219 	mutex_exit(&pidlinklock);
220 
221 	return (newpid);
222 
223 failed:
224 	mutex_exit(&pidlinklock);
225 	kmem_free(pidp, sizeof (struct pid));
226 	return (-1);
227 }
228 
229 /*
230  * decrement the reference count for pid
231  */
232 int
233 pid_rele(struct pid *pidp)
234 {
235 	struct pid **pidpp;
236 
237 	mutex_enter(&pidlinklock);
238 	ASSERT(pidp != &pid0);
239 
240 	pidpp = &HASHPID(pidp->pid_id);
241 	for (;;) {
242 		ASSERT(*pidpp != NULL);
243 		if (*pidpp == pidp)
244 			break;
245 		pidpp = &(*pidpp)->pid_link;
246 	}
247 
248 	*pidpp = pidp->pid_link;
249 	mutex_exit(&pidlinklock);
250 
251 	kmem_free(pidp, sizeof (*pidp));
252 	return (0);
253 }
254 
255 void
256 proc_entry_free(struct pid *pidp)
257 {
258 	mutex_enter(&pidlinklock);
259 	pidp->pid_prinactive = 1;
260 	procdir[pidp->pid_prslot].pe_next = procentfree;
261 	procentfree = &procdir[pidp->pid_prslot];
262 	mutex_exit(&pidlinklock);
263 }
264 
265 /*
266  * The original task needs to be passed in since the process has already been
267  * detached from the task at this point in time.
268  */
269 void
270 pid_exit(proc_t *prp, struct task *tk)
271 {
272 	struct pid *pidp;
273 	zone_t	*zone = prp->p_zone;
274 
275 	ASSERT(MUTEX_HELD(&pidlock));
276 
277 	/*
278 	 * Exit process group.  If it is NULL, it's because fork failed
279 	 * before calling pgjoin().
280 	 */
281 	ASSERT(prp->p_pgidp != NULL || prp->p_stat == SIDL);
282 	if (prp->p_pgidp != NULL)
283 		pgexit(prp);
284 
285 	sess_rele(prp->p_sessp, B_TRUE);
286 
287 	pidp = prp->p_pidp;
288 
289 	proc_entry_free(pidp);
290 
291 	if (audit_active)
292 		audit_pfree(prp);
293 
294 	if (practive == prp) {
295 		practive = prp->p_next;
296 	}
297 
298 	if (prp->p_next) {
299 		prp->p_next->p_prev = prp->p_prev;
300 	}
301 	if (prp->p_prev) {
302 		prp->p_prev->p_next = prp->p_next;
303 	}
304 
305 	PID_RELE(pidp);
306 
307 	mutex_destroy(&prp->p_crlock);
308 	kmem_cache_free(process_cache, prp);
309 	nproc--;
310 
311 	/*
312 	 * Decrement the process counts of the original task, project and zone.
313 	 */
314 	mutex_enter(&zone->zone_nlwps_lock);
315 	tk->tk_nprocs--;
316 	tk->tk_proj->kpj_nprocs--;
317 	zone->zone_nprocs--;
318 	mutex_exit(&zone->zone_nlwps_lock);
319 }
320 
321 /*
322  * Find a process visible from the specified zone given its process ID.
323  */
324 proc_t *
325 prfind_zone(pid_t pid, zoneid_t zoneid)
326 {
327 	struct pid *pidp;
328 	proc_t *p;
329 
330 	ASSERT(MUTEX_HELD(&pidlock));
331 
332 	mutex_enter(&pidlinklock);
333 	pidp = pid_lookup(pid);
334 	mutex_exit(&pidlinklock);
335 	if (pidp != NULL && pidp->pid_prinactive == 0) {
336 		p = procdir[pidp->pid_prslot].pe_proc;
337 		if (zoneid == ALL_ZONES || p->p_zone->zone_id == zoneid)
338 			return (p);
339 	}
340 	return (NULL);
341 }
342 
343 /*
344  * Find a process given its process ID.  This obeys zone restrictions,
345  * so if the caller is in a non-global zone it won't find processes
346  * associated with other zones.  Use prfind_zone(pid, ALL_ZONES) to
347  * bypass this restriction.
348  */
349 proc_t *
350 prfind(pid_t pid)
351 {
352 	zoneid_t zoneid;
353 
354 	if (INGLOBALZONE(curproc))
355 		zoneid = ALL_ZONES;
356 	else
357 		zoneid = getzoneid();
358 	return (prfind_zone(pid, zoneid));
359 }
360 
361 proc_t *
362 pgfind_zone(pid_t pgid, zoneid_t zoneid)
363 {
364 	struct pid *pidp;
365 
366 	ASSERT(MUTEX_HELD(&pidlock));
367 
368 	mutex_enter(&pidlinklock);
369 	pidp = pid_lookup(pgid);
370 	mutex_exit(&pidlinklock);
371 	if (pidp != NULL) {
372 		proc_t *p = pidp->pid_pglink;
373 
374 		if (zoneid == ALL_ZONES || pgid == 0 || p == NULL ||
375 		    p->p_zone->zone_id == zoneid)
376 			return (p);
377 	}
378 	return (NULL);
379 }
380 
381 /*
382  * return the head of the list of processes whose process group ID is 'pgid',
383  * or NULL, if no such process group
384  */
385 proc_t *
386 pgfind(pid_t pgid)
387 {
388 	zoneid_t zoneid;
389 
390 	if (INGLOBALZONE(curproc))
391 		zoneid = ALL_ZONES;
392 	else
393 		zoneid = getzoneid();
394 	return (pgfind_zone(pgid, zoneid));
395 }
396 
397 /*
398  * Sets P_PR_LOCK on a non-system process.  Process must be fully created
399  * and not exiting to succeed.
400  *
401  * Returns 0 on success.
402  * Returns 1 if P_PR_LOCK is set.
403  * Returns -1 if proc is in invalid state.
404  */
405 int
406 sprtrylock_proc(proc_t *p)
407 {
408 	ASSERT(MUTEX_HELD(&p->p_lock));
409 
410 	/* skip system and incomplete processes */
411 	if (p->p_stat == SIDL || p->p_stat == SZOMB ||
412 	    (p->p_flag & (SSYS | SEXITING | SEXITLWPS))) {
413 		return (-1);
414 	}
415 
416 	if (p->p_proc_flag & P_PR_LOCK)
417 		return (1);
418 
419 	p->p_proc_flag |= P_PR_LOCK;
420 	THREAD_KPRI_REQUEST();
421 
422 	return (0);
423 }
424 
425 /*
426  * Wait for P_PR_LOCK to become clear.  Returns with p_lock dropped,
427  * and the proc pointer no longer valid, as the proc may have exited.
428  */
429 void
430 sprwaitlock_proc(proc_t *p)
431 {
432 	kmutex_t *mp;
433 
434 	ASSERT(MUTEX_HELD(&p->p_lock));
435 	ASSERT(p->p_proc_flag & P_PR_LOCK);
436 
437 	/*
438 	 * p_lock is persistent, but p itself is not -- it could
439 	 * vanish during cv_wait().  Load p->p_lock now so we can
440 	 * drop it after cv_wait() without referencing p.
441 	 */
442 	mp = &p->p_lock;
443 	cv_wait(&pr_pid_cv[p->p_slot], mp);
444 	mutex_exit(mp);
445 }
446 
447 /*
448  * If pid exists, find its proc, acquire its p_lock and mark it P_PR_LOCK.
449  * Returns the proc pointer on success, NULL on failure.  sprlock() is
450  * really just a stripped-down version of pr_p_lock() to allow practive
451  * walkers like dofusers() and dumpsys() to synchronize with /proc.
452  */
453 proc_t *
454 sprlock_zone(pid_t pid, zoneid_t zoneid)
455 {
456 	proc_t *p;
457 	int ret;
458 
459 	for (;;) {
460 		mutex_enter(&pidlock);
461 		if ((p = prfind_zone(pid, zoneid)) == NULL) {
462 			mutex_exit(&pidlock);
463 			return (NULL);
464 		}
465 		mutex_enter(&p->p_lock);
466 		mutex_exit(&pidlock);
467 
468 		if (panicstr)
469 			return (p);
470 
471 		ret = sprtrylock_proc(p);
472 		if (ret == -1) {
473 			mutex_exit(&p->p_lock);
474 			return (NULL);
475 		} else if (ret == 0) {
476 			break;
477 		}
478 		sprwaitlock_proc(p);
479 	}
480 	return (p);
481 }
482 
483 proc_t *
484 sprlock(pid_t pid)
485 {
486 	zoneid_t zoneid;
487 
488 	if (INGLOBALZONE(curproc))
489 		zoneid = ALL_ZONES;
490 	else
491 		zoneid = getzoneid();
492 	return (sprlock_zone(pid, zoneid));
493 }
494 
495 void
496 sprlock_proc(proc_t *p)
497 {
498 	ASSERT(MUTEX_HELD(&p->p_lock));
499 
500 	while (p->p_proc_flag & P_PR_LOCK) {
501 		cv_wait(&pr_pid_cv[p->p_slot], &p->p_lock);
502 	}
503 
504 	p->p_proc_flag |= P_PR_LOCK;
505 	THREAD_KPRI_REQUEST();
506 }
507 
508 void
509 sprunlock(proc_t *p)
510 {
511 	if (panicstr) {
512 		mutex_exit(&p->p_lock);
513 		return;
514 	}
515 
516 	ASSERT(p->p_proc_flag & P_PR_LOCK);
517 	ASSERT(MUTEX_HELD(&p->p_lock));
518 
519 	cv_signal(&pr_pid_cv[p->p_slot]);
520 	p->p_proc_flag &= ~P_PR_LOCK;
521 	mutex_exit(&p->p_lock);
522 	THREAD_KPRI_RELEASE();
523 }
524 
525 void
526 pid_init(void)
527 {
528 	int i;
529 
530 	pid_hashsz = 1 << highbit(v.v_proc / pid_hashlen);
531 
532 	pidhash = kmem_zalloc(sizeof (struct pid *) * pid_hashsz, KM_SLEEP);
533 	procdir = kmem_alloc(sizeof (union procent) * v.v_proc, KM_SLEEP);
534 	pr_pid_cv = kmem_zalloc(sizeof (kcondvar_t) * v.v_proc, KM_SLEEP);
535 	proc_lock = kmem_zalloc(sizeof (struct plock) * v.v_proc, KM_SLEEP);
536 
537 	nproc = 1;
538 	practive = proc_sched;
539 	proc_sched->p_next = NULL;
540 	procdir[0].pe_proc = proc_sched;
541 
542 	procentfree = &procdir[1];
543 	for (i = 1; i < v.v_proc - 1; i++)
544 		procdir[i].pe_next = &procdir[i+1];
545 	procdir[i].pe_next = NULL;
546 
547 	HASHPID(0) = &pid0;
548 
549 	upcount_init();
550 }
551 
552 proc_t *
553 pid_entry(int slot)
554 {
555 	union procent *pep;
556 	proc_t *prp;
557 
558 	ASSERT(MUTEX_HELD(&pidlock));
559 	ASSERT(slot >= 0 && slot < v.v_proc);
560 
561 	pep = procdir[slot].pe_next;
562 	if (pep >= procdir && pep < &procdir[v.v_proc])
563 		return (NULL);
564 	prp = procdir[slot].pe_proc;
565 	if (prp != 0 && prp->p_stat == SIDL)
566 		return (NULL);
567 	return (prp);
568 }
569 
570 /*
571  * Send the specified signal to all processes whose process group ID is
572  * equal to 'pgid'
573  */
574 
575 void
576 signal(pid_t pgid, int sig)
577 {
578 	struct pid *pidp;
579 	proc_t *prp;
580 
581 	mutex_enter(&pidlock);
582 	mutex_enter(&pidlinklock);
583 	if (pgid == 0 || (pidp = pid_lookup(pgid)) == NULL) {
584 		mutex_exit(&pidlinklock);
585 		mutex_exit(&pidlock);
586 		return;
587 	}
588 	mutex_exit(&pidlinklock);
589 	for (prp = pidp->pid_pglink; prp; prp = prp->p_pglink) {
590 		mutex_enter(&prp->p_lock);
591 		sigtoproc(prp, NULL, sig);
592 		mutex_exit(&prp->p_lock);
593 	}
594 	mutex_exit(&pidlock);
595 }
596 
597 /*
598  * Send the specified signal to the specified process
599  */
600 
601 void
602 prsignal(struct pid *pidp, int sig)
603 {
604 	if (!(pidp->pid_prinactive))
605 		psignal(procdir[pidp->pid_prslot].pe_proc, sig);
606 }
607 
608 #include <sys/sunddi.h>
609 
610 /*
611  * DDI/DKI interfaces for drivers to send signals to processes
612  */
613 
614 /*
615  * obtain an opaque reference to a process for signaling
616  */
617 void *
618 proc_ref(void)
619 {
620 	struct pid *pidp;
621 
622 	mutex_enter(&pidlock);
623 	pidp = curproc->p_pidp;
624 	PID_HOLD(pidp);
625 	mutex_exit(&pidlock);
626 
627 	return (pidp);
628 }
629 
630 /*
631  * release a reference to a process
632  * - a process can exit even if a driver has a reference to it
633  * - one proc_unref for every proc_ref
634  */
635 void
636 proc_unref(void *pref)
637 {
638 	mutex_enter(&pidlock);
639 	PID_RELE((struct pid *)pref);
640 	mutex_exit(&pidlock);
641 }
642 
643 /*
644  * send a signal to a process
645  *
646  * - send the process the signal
647  * - if the process went away, return a -1
648  * - if the process is still there return 0
649  */
650 int
651 proc_signal(void *pref, int sig)
652 {
653 	struct pid *pidp = pref;
654 
655 	prsignal(pidp, sig);
656 	return (pidp->pid_prinactive ? -1 : 0);
657 }
658 
659 
660 static struct upcount	**upc_hash;	/* a boot time allocated array */
661 static ulong_t		upc_hashmask;
662 #define	UPC_HASH(x, y)	((ulong_t)(x ^ y) & upc_hashmask)
663 
664 /*
665  * Get us off the ground.  Called once at boot.
666  */
667 void
668 upcount_init(void)
669 {
670 	ulong_t	upc_hashsize;
671 
672 	/*
673 	 * An entry per MB of memory is our current guess
674 	 */
675 	/*
676 	 * 2^20 is a meg, so shifting right by 20 - PAGESHIFT
677 	 * converts pages to megs (without overflowing a u_int
678 	 * if you have more than 4G of memory, like ptob(physmem)/1M
679 	 * would).
680 	 */
681 	upc_hashsize = (1 << highbit(physmem >> (20 - PAGESHIFT)));
682 	upc_hashmask = upc_hashsize - 1;
683 	upc_hash = kmem_zalloc(upc_hashsize * sizeof (struct upcount *),
684 	    KM_SLEEP);
685 }
686 
687 /*
688  * Increment the number of processes associated with a given uid and zoneid.
689  */
690 void
691 upcount_inc(uid_t uid, zoneid_t zoneid)
692 {
693 	struct upcount	**upc, **hupc;
694 	struct upcount	*new;
695 
696 	ASSERT(MUTEX_HELD(&pidlock));
697 	new = NULL;
698 	hupc = &upc_hash[UPC_HASH(uid, zoneid)];
699 top:
700 	upc = hupc;
701 	while ((*upc) != NULL) {
702 		if ((*upc)->up_uid == uid && (*upc)->up_zoneid == zoneid) {
703 			(*upc)->up_count++;
704 			if (new) {
705 				/*
706 				 * did not need `new' afterall.
707 				 */
708 				kmem_free(new, sizeof (*new));
709 			}
710 			return;
711 		}
712 		upc = &(*upc)->up_next;
713 	}
714 
715 	/*
716 	 * There is no entry for this <uid,zoneid> pair.
717 	 * Allocate one.  If we have to drop pidlock, check
718 	 * again.
719 	 */
720 	if (new == NULL) {
721 		new = (struct upcount *)kmem_alloc(sizeof (*new), KM_NOSLEEP);
722 		if (new == NULL) {
723 			mutex_exit(&pidlock);
724 			new = (struct upcount *)kmem_alloc(sizeof (*new),
725 			    KM_SLEEP);
726 			mutex_enter(&pidlock);
727 			goto top;
728 		}
729 	}
730 
731 
732 	/*
733 	 * On the assumption that a new user is going to do some
734 	 * more forks, put the new upcount structure on the front.
735 	 */
736 	upc = hupc;
737 
738 	new->up_uid = uid;
739 	new->up_zoneid = zoneid;
740 	new->up_count = 1;
741 	new->up_next = *upc;
742 
743 	*upc = new;
744 }
745 
746 /*
747  * Decrement the number of processes a given uid and zoneid has.
748  */
749 void
750 upcount_dec(uid_t uid, zoneid_t zoneid)
751 {
752 	struct	upcount **upc;
753 	struct	upcount *done;
754 
755 	ASSERT(MUTEX_HELD(&pidlock));
756 
757 	upc = &upc_hash[UPC_HASH(uid, zoneid)];
758 	while ((*upc) != NULL) {
759 		if ((*upc)->up_uid == uid && (*upc)->up_zoneid == zoneid) {
760 			(*upc)->up_count--;
761 			if ((*upc)->up_count == 0) {
762 				done = *upc;
763 				*upc = (*upc)->up_next;
764 				kmem_free(done, sizeof (*done));
765 			}
766 			return;
767 		}
768 		upc = &(*upc)->up_next;
769 	}
770 	cmn_err(CE_PANIC, "decr_upcount-off the end");
771 }
772 
773 /*
774  * Returns the number of processes a uid has.
775  * Non-existent uid's are assumed to have no processes.
776  */
777 int
778 upcount_get(uid_t uid, zoneid_t zoneid)
779 {
780 	struct	upcount *upc;
781 
782 	ASSERT(MUTEX_HELD(&pidlock));
783 
784 	upc = upc_hash[UPC_HASH(uid, zoneid)];
785 	while (upc != NULL) {
786 		if (upc->up_uid == uid && upc->up_zoneid == zoneid) {
787 			return (upc->up_count);
788 		}
789 		upc = upc->up_next;
790 	}
791 	return (0);
792 }
793