xref: /dflybsd-src/sys/kern/kern_proc.c (revision a12ef770ba351628dde7e68bd7b722ae54dd554b)
1 /*
2  * Copyright (c) 1982, 1986, 1989, 1991, 1993
3  *	The Regents of the University of California.  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 the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  *	@(#)kern_proc.c	8.7 (Berkeley) 2/14/95
34  * $FreeBSD: src/sys/kern/kern_proc.c,v 1.63.2.9 2003/05/08 07:47:16 kbyanc Exp $
35  * $DragonFly: src/sys/kern/kern_proc.c,v 1.18 2005/02/01 02:25:45 joerg Exp $
36  */
37 
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/kernel.h>
41 #include <sys/sysctl.h>
42 #include <sys/malloc.h>
43 #include <sys/proc.h>
44 #include <sys/jail.h>
45 #include <sys/filedesc.h>
46 #include <sys/tty.h>
47 #include <sys/signalvar.h>
48 #include <vm/vm.h>
49 #include <sys/lock.h>
50 #include <vm/pmap.h>
51 #include <vm/vm_map.h>
52 #include <sys/user.h>
53 #include <vm/vm_zone.h>
54 #include <machine/smp.h>
55 
56 static MALLOC_DEFINE(M_PGRP, "pgrp", "process group header");
57 MALLOC_DEFINE(M_SESSION, "session", "session header");
58 static MALLOC_DEFINE(M_PROC, "proc", "Proc structures");
59 MALLOC_DEFINE(M_SUBPROC, "subproc", "Proc sub-structures");
60 
61 int ps_showallprocs = 1;
62 static int ps_showallthreads = 1;
63 SYSCTL_INT(_kern, OID_AUTO, ps_showallprocs, CTLFLAG_RW,
64     &ps_showallprocs, 0, "");
65 SYSCTL_INT(_kern, OID_AUTO, ps_showallthreads, CTLFLAG_RW,
66     &ps_showallthreads, 0, "");
67 
68 static void pgdelete	(struct pgrp *);
69 
70 static void	orphanpg (struct pgrp *pg);
71 
72 /*
73  * Other process lists
74  */
75 struct pidhashhead *pidhashtbl;
76 u_long pidhash;
77 struct pgrphashhead *pgrphashtbl;
78 u_long pgrphash;
79 struct proclist allproc;
80 struct proclist zombproc;
81 vm_zone_t proc_zone;
82 vm_zone_t thread_zone;
83 
84 /*
85  * Initialize global process hashing structures.
86  */
87 void
88 procinit()
89 {
90 
91 	LIST_INIT(&allproc);
92 	LIST_INIT(&zombproc);
93 	pidhashtbl = hashinit(maxproc / 4, M_PROC, &pidhash);
94 	pgrphashtbl = hashinit(maxproc / 4, M_PROC, &pgrphash);
95 	proc_zone = zinit("PROC", sizeof (struct proc), 0, 0, 5);
96 	thread_zone = zinit("THREAD", sizeof (struct thread), 0, 0, 5);
97 	uihashinit();
98 }
99 
100 /*
101  * Is p an inferior of the current process?
102  */
103 int
104 inferior(p)
105 	struct proc *p;
106 {
107 
108 	for (; p != curproc; p = p->p_pptr)
109 		if (p->p_pid == 0)
110 			return (0);
111 	return (1);
112 }
113 
114 /*
115  * Locate a process by number
116  */
117 struct proc *
118 pfind(pid)
119 	pid_t pid;
120 {
121 	struct proc *p;
122 
123 	LIST_FOREACH(p, PIDHASH(pid), p_hash)
124 		if (p->p_pid == pid)
125 			return (p);
126 	return (NULL);
127 }
128 
129 /*
130  * Locate a process group by number
131  */
132 struct pgrp *
133 pgfind(pgid)
134 	pid_t pgid;
135 {
136 	struct pgrp *pgrp;
137 
138 	LIST_FOREACH(pgrp, PGRPHASH(pgid), pg_hash)
139 		if (pgrp->pg_id == pgid)
140 			return (pgrp);
141 	return (NULL);
142 }
143 
144 /*
145  * Move p to a new or existing process group (and session)
146  */
147 int
148 enterpgrp(p, pgid, mksess)
149 	struct proc *p;
150 	pid_t pgid;
151 	int mksess;
152 {
153 	struct pgrp *pgrp = pgfind(pgid);
154 
155 	KASSERT(pgrp == NULL || !mksess,
156 	    ("enterpgrp: setsid into non-empty pgrp"));
157 	KASSERT(!SESS_LEADER(p),
158 	    ("enterpgrp: session leader attempted setpgrp"));
159 
160 	if (pgrp == NULL) {
161 		pid_t savepid = p->p_pid;
162 		struct proc *np;
163 		/*
164 		 * new process group
165 		 */
166 		KASSERT(p->p_pid == pgid,
167 		    ("enterpgrp: new pgrp and pid != pgid"));
168 		if ((np = pfind(savepid)) == NULL || np != p)
169 			return (ESRCH);
170 		MALLOC(pgrp, struct pgrp *, sizeof(struct pgrp), M_PGRP,
171 		    M_WAITOK);
172 		if (mksess) {
173 			struct session *sess;
174 
175 			/*
176 			 * new session
177 			 */
178 			MALLOC(sess, struct session *, sizeof(struct session),
179 			    M_SESSION, M_WAITOK);
180 			sess->s_leader = p;
181 			sess->s_sid = p->p_pid;
182 			sess->s_count = 1;
183 			sess->s_ttyvp = NULL;
184 			sess->s_ttyp = NULL;
185 			bcopy(p->p_session->s_login, sess->s_login,
186 			    sizeof(sess->s_login));
187 			p->p_flag &= ~P_CONTROLT;
188 			pgrp->pg_session = sess;
189 			KASSERT(p == curproc,
190 			    ("enterpgrp: mksession and p != curproc"));
191 		} else {
192 			pgrp->pg_session = p->p_session;
193 			sess_hold(pgrp->pg_session);
194 		}
195 		pgrp->pg_id = pgid;
196 		LIST_INIT(&pgrp->pg_members);
197 		LIST_INSERT_HEAD(PGRPHASH(pgid), pgrp, pg_hash);
198 		pgrp->pg_jobc = 0;
199 		SLIST_INIT(&pgrp->pg_sigiolst);
200 	} else if (pgrp == p->p_pgrp)
201 		return (0);
202 
203 	/*
204 	 * Adjust eligibility of affected pgrps to participate in job control.
205 	 * Increment eligibility counts before decrementing, otherwise we
206 	 * could reach 0 spuriously during the first call.
207 	 */
208 	fixjobc(p, pgrp, 1);
209 	fixjobc(p, p->p_pgrp, 0);
210 
211 	LIST_REMOVE(p, p_pglist);
212 	if (LIST_EMPTY(&p->p_pgrp->pg_members))
213 		pgdelete(p->p_pgrp);
214 	p->p_pgrp = pgrp;
215 	LIST_INSERT_HEAD(&pgrp->pg_members, p, p_pglist);
216 	return (0);
217 }
218 
219 /*
220  * remove process from process group
221  */
222 int
223 leavepgrp(p)
224 	struct proc *p;
225 {
226 
227 	LIST_REMOVE(p, p_pglist);
228 	if (LIST_EMPTY(&p->p_pgrp->pg_members))
229 		pgdelete(p->p_pgrp);
230 	p->p_pgrp = 0;
231 	return (0);
232 }
233 
234 /*
235  * delete a process group
236  */
237 static void
238 pgdelete(pgrp)
239 	struct pgrp *pgrp;
240 {
241 
242 	/*
243 	 * Reset any sigio structures pointing to us as a result of
244 	 * F_SETOWN with our pgid.
245 	 */
246 	funsetownlst(&pgrp->pg_sigiolst);
247 
248 	if (pgrp->pg_session->s_ttyp != NULL &&
249 	    pgrp->pg_session->s_ttyp->t_pgrp == pgrp)
250 		pgrp->pg_session->s_ttyp->t_pgrp = NULL;
251 	LIST_REMOVE(pgrp, pg_hash);
252 	sess_rele(pgrp->pg_session);
253 	free(pgrp, M_PGRP);
254 }
255 
256 /*
257  * Adjust the ref count on a session structure.  When the ref count falls to
258  * zero the tty is disassociated from the session and the session structure
259  * is freed.  Note that tty assocation is not itself ref-counted.
260  */
261 void
262 sess_hold(struct session *sp)
263 {
264 	++sp->s_count;
265 }
266 
267 void
268 sess_rele(struct session *sp)
269 {
270 	KKASSERT(sp->s_count > 0);
271 	if (--sp->s_count == 0) {
272 		if (sp->s_ttyp && sp->s_ttyp->t_session) {
273 #ifdef TTY_DO_FULL_CLOSE
274 			/* FULL CLOSE, see ttyclearsession() */
275 			KKASSERT(sp->s_ttyp->t_session == sp);
276 			sp->s_ttyp->t_session = NULL;
277 #else
278 			/* HALF CLOSE, see ttyclearsession() */
279 			if (sp->s_ttyp->t_session == sp)
280 				sp->s_ttyp->t_session = NULL;
281 #endif
282 		}
283 		free(sp, M_SESSION);
284 	}
285 }
286 
287 /*
288  * Adjust pgrp jobc counters when specified process changes process group.
289  * We count the number of processes in each process group that "qualify"
290  * the group for terminal job control (those with a parent in a different
291  * process group of the same session).  If that count reaches zero, the
292  * process group becomes orphaned.  Check both the specified process'
293  * process group and that of its children.
294  * entering == 0 => p is leaving specified group.
295  * entering == 1 => p is entering specified group.
296  */
297 void
298 fixjobc(p, pgrp, entering)
299 	struct proc *p;
300 	struct pgrp *pgrp;
301 	int entering;
302 {
303 	struct pgrp *hispgrp;
304 	struct session *mysession = pgrp->pg_session;
305 
306 	/*
307 	 * Check p's parent to see whether p qualifies its own process
308 	 * group; if so, adjust count for p's process group.
309 	 */
310 	if ((hispgrp = p->p_pptr->p_pgrp) != pgrp &&
311 	    hispgrp->pg_session == mysession) {
312 		if (entering)
313 			pgrp->pg_jobc++;
314 		else if (--pgrp->pg_jobc == 0)
315 			orphanpg(pgrp);
316 	}
317 
318 	/*
319 	 * Check this process' children to see whether they qualify
320 	 * their process groups; if so, adjust counts for children's
321 	 * process groups.
322 	 */
323 	LIST_FOREACH(p, &p->p_children, p_sibling)
324 		if ((hispgrp = p->p_pgrp) != pgrp &&
325 		    hispgrp->pg_session == mysession &&
326 		    p->p_stat != SZOMB) {
327 			if (entering)
328 				hispgrp->pg_jobc++;
329 			else if (--hispgrp->pg_jobc == 0)
330 				orphanpg(hispgrp);
331 		}
332 }
333 
334 /*
335  * A process group has become orphaned;
336  * if there are any stopped processes in the group,
337  * hang-up all process in that group.
338  */
339 static void
340 orphanpg(pg)
341 	struct pgrp *pg;
342 {
343 	struct proc *p;
344 
345 	LIST_FOREACH(p, &pg->pg_members, p_pglist) {
346 		if (p->p_stat == SSTOP) {
347 			LIST_FOREACH(p, &pg->pg_members, p_pglist) {
348 				psignal(p, SIGHUP);
349 				psignal(p, SIGCONT);
350 			}
351 			return;
352 		}
353 	}
354 }
355 
356 #include "opt_ddb.h"
357 #ifdef DDB
358 #include <ddb/ddb.h>
359 
360 DB_SHOW_COMMAND(pgrpdump, pgrpdump)
361 {
362 	struct pgrp *pgrp;
363 	struct proc *p;
364 	int i;
365 
366 	for (i = 0; i <= pgrphash; i++) {
367 		if (!LIST_EMPTY(&pgrphashtbl[i])) {
368 			printf("\tindx %d\n", i);
369 			LIST_FOREACH(pgrp, &pgrphashtbl[i], pg_hash) {
370 				printf(
371 			"\tpgrp %p, pgid %ld, sess %p, sesscnt %d, mem %p\n",
372 				    (void *)pgrp, (long)pgrp->pg_id,
373 				    (void *)pgrp->pg_session,
374 				    pgrp->pg_session->s_count,
375 				    (void *)LIST_FIRST(&pgrp->pg_members));
376 				LIST_FOREACH(p, &pgrp->pg_members, p_pglist) {
377 					printf("\t\tpid %ld addr %p pgrp %p\n",
378 					    (long)p->p_pid, (void *)p,
379 					    (void *)p->p_pgrp);
380 				}
381 			}
382 		}
383 	}
384 }
385 #endif /* DDB */
386 
387 /*
388  * Fill in an eproc structure for the specified thread.
389  */
390 void
391 fill_eproc_td(thread_t td, struct eproc *ep, struct proc *xp)
392 {
393 	bzero(ep, sizeof(*ep));
394 
395 	ep->e_uticks = td->td_uticks;
396 	ep->e_sticks = td->td_sticks;
397 	ep->e_iticks = td->td_iticks;
398 	ep->e_tdev = NOUDEV;
399 	ep->e_cpuid = td->td_gd->gd_cpuid;
400 	if (td->td_wmesg) {
401 		strncpy(ep->e_wmesg, td->td_wmesg, WMESGLEN);
402 		ep->e_wmesg[WMESGLEN] = 0;
403 	}
404 
405 	/*
406 	 * Fake up portions of the proc structure copied out by the sysctl
407 	 * to return useful information.  Note that using td_pri directly
408 	 * is messy because it includes critial section data so we fake
409 	 * up an rtprio.prio for threads.
410 	 */
411 	if (xp) {
412 		*xp = *initproc;
413 		xp->p_rtprio.type = RTP_PRIO_THREAD;
414 		xp->p_rtprio.prio = td->td_pri & TDPRI_MASK;
415 		xp->p_pid = -1;
416 	}
417 }
418 
419 /*
420  * Fill in an eproc structure for the specified process.
421  */
422 void
423 fill_eproc(struct proc *p, struct eproc *ep)
424 {
425 	struct tty *tp;
426 
427 	fill_eproc_td(p->p_thread, ep, NULL);
428 
429 	ep->e_paddr = p;
430 	if (p->p_ucred) {
431 		ep->e_ucred = *p->p_ucred;
432 	}
433 	if (p->p_procsig) {
434 		ep->e_procsig = *p->p_procsig;
435 	}
436 	if (p->p_stat != SIDL && p->p_stat != SZOMB && p->p_vmspace != NULL) {
437 		struct vmspace *vm = p->p_vmspace;
438 		ep->e_vm = *vm;
439 		ep->e_vm.vm_rssize = vmspace_resident_count(vm); /*XXX*/
440 	}
441 	if ((p->p_flag & P_INMEM) && p->p_stats)
442 		ep->e_stats = *p->p_stats;
443 	if (p->p_pptr)
444 		ep->e_ppid = p->p_pptr->p_pid;
445 	if (p->p_pgrp) {
446 		ep->e_pgid = p->p_pgrp->pg_id;
447 		ep->e_jobc = p->p_pgrp->pg_jobc;
448 		ep->e_sess = p->p_pgrp->pg_session;
449 
450 		if (ep->e_sess) {
451 			bcopy(ep->e_sess->s_login, ep->e_login, sizeof(ep->e_login));
452 			if (ep->e_sess->s_ttyvp)
453 				ep->e_flag = EPROC_CTTY;
454 			if (p->p_session && SESS_LEADER(p))
455 				ep->e_flag |= EPROC_SLEADER;
456 		}
457 	}
458 	if ((p->p_flag & P_CONTROLT) &&
459 	    (ep->e_sess != NULL) &&
460 	    ((tp = ep->e_sess->s_ttyp) != NULL)) {
461 		ep->e_tdev = dev2udev(tp->t_dev);
462 		ep->e_tpgid = tp->t_pgrp ? tp->t_pgrp->pg_id : NO_PID;
463 		ep->e_tsess = tp->t_session;
464 	} else {
465 		ep->e_tdev = NOUDEV;
466 	}
467 }
468 
469 struct proc *
470 zpfind(pid_t pid)
471 {
472 	struct proc *p;
473 
474 	LIST_FOREACH(p, &zombproc, p_list)
475 		if (p->p_pid == pid)
476 			return (p);
477 	return (NULL);
478 }
479 
480 static int
481 sysctl_out_proc(struct proc *p, struct thread *td, struct sysctl_req *req, int doingzomb)
482 {
483 	struct eproc eproc;
484 	struct proc xproc;
485 	int error;
486 #if 0
487 	pid_t pid = p->p_pid;
488 #endif
489 
490 	if (p) {
491 		td = p->p_thread;
492 		fill_eproc(p, &eproc);
493 		xproc = *p;
494 
495 		/*
496 		 * Fixup p_stat from SRUN to SSLEEP if the LWKT thread is
497 		 * in a thread-blocked state.
498 		 *
499 		 * XXX temporary fix which might become permanent (I'd rather
500 		 * not pollute the thread scheduler with knowlege about
501 		 * processes).
502 		 */
503 		if (p->p_stat == SRUN && td && (td->td_flags & TDF_BLOCKED)) {
504 			xproc.p_stat = SSLEEP;
505 		}
506 	} else if (td) {
507 		fill_eproc_td(td, &eproc, &xproc);
508 	}
509 	error = SYSCTL_OUT(req,(caddr_t)&xproc, sizeof(struct proc));
510 	if (error)
511 		return (error);
512 	error = SYSCTL_OUT(req,(caddr_t)&eproc, sizeof(eproc));
513 	if (error)
514 		return (error);
515 	error = SYSCTL_OUT(req,(caddr_t)td, sizeof(struct thread));
516 	if (error)
517 		return (error);
518 #if 0
519 	if (!doingzomb && pid && (pfind(pid) != p))
520 		return EAGAIN;
521 	if (doingzomb && zpfind(pid) != p)
522 		return EAGAIN;
523 #endif
524 	return (0);
525 }
526 
527 static int
528 sysctl_kern_proc(SYSCTL_HANDLER_ARGS)
529 {
530 	int *name = (int*) arg1;
531 	u_int namelen = arg2;
532 	struct proc *p;
533 	struct thread *td;
534 	int doingzomb;
535 	int error = 0;
536 	int n;
537 	int origcpu;
538 	struct ucred *cr1 = curproc->p_ucred;
539 
540 	if (oidp->oid_number == KERN_PROC_PID) {
541 		if (namelen != 1)
542 			return (EINVAL);
543 		p = pfind((pid_t)name[0]);
544 		if (!p)
545 			return (0);
546 		if (!PRISON_CHECK(cr1, p->p_ucred))
547 			return (0);
548 		error = sysctl_out_proc(p, NULL, req, 0);
549 		return (error);
550 	}
551 	if (oidp->oid_number == KERN_PROC_ALL && !namelen)
552 		;
553 	else if (oidp->oid_number != KERN_PROC_ALL && namelen == 1)
554 		;
555 	else
556 		return (EINVAL);
557 
558 	if (!req->oldptr) {
559 		/* overestimate by 5 procs */
560 		error = SYSCTL_OUT(req, 0, sizeof (struct kinfo_proc) * 5);
561 		if (error)
562 			return (error);
563 	}
564 	for (doingzomb=0 ; doingzomb < 2 ; doingzomb++) {
565 		if (!doingzomb)
566 			p = LIST_FIRST(&allproc);
567 		else
568 			p = LIST_FIRST(&zombproc);
569 		for (; p != 0; p = LIST_NEXT(p, p_list)) {
570 			/*
571 			 * Show a user only their processes.
572 			 */
573 			if ((!ps_showallprocs) && p_trespass(cr1, p->p_ucred))
574 				continue;
575 			/*
576 			 * Skip embryonic processes.
577 			 */
578 			if (p->p_stat == SIDL)
579 				continue;
580 			/*
581 			 * TODO - make more efficient (see notes below).
582 			 * do by session.
583 			 */
584 			switch (oidp->oid_number) {
585 			case KERN_PROC_PGRP:
586 				/* could do this by traversing pgrp */
587 				if (p->p_pgrp == NULL ||
588 				    p->p_pgrp->pg_id != (pid_t)name[0])
589 					continue;
590 				break;
591 
592 			case KERN_PROC_TTY:
593 				if ((p->p_flag & P_CONTROLT) == 0 ||
594 				    p->p_session == NULL ||
595 				    p->p_session->s_ttyp == NULL ||
596 				    dev2udev(p->p_session->s_ttyp->t_dev) !=
597 					(udev_t)name[0])
598 					continue;
599 				break;
600 
601 			case KERN_PROC_UID:
602 				if (p->p_ucred == NULL ||
603 				    p->p_ucred->cr_uid != (uid_t)name[0])
604 					continue;
605 				break;
606 
607 			case KERN_PROC_RUID:
608 				if (p->p_ucred == NULL ||
609 				    p->p_ucred->cr_ruid != (uid_t)name[0])
610 					continue;
611 				break;
612 			}
613 
614 			if (!PRISON_CHECK(cr1, p->p_ucred))
615 				continue;
616 			PHOLD(p);
617 			error = sysctl_out_proc(p, NULL, req, doingzomb);
618 			PRELE(p);
619 			if (error)
620 				return (error);
621 		}
622 	}
623 
624 	/*
625 	 * Iterate over all active cpus and scan their thread list.  Start
626 	 * with the next logical cpu and end with our original cpu.  We
627 	 * migrate our own thread to each target cpu in order to safely scan
628 	 * its thread list.  In the last loop we migrate back to our original
629 	 * cpu.
630 	 */
631 	origcpu = mycpu->gd_cpuid;
632 	if (!ps_showallthreads || jailed(cr1))
633 		goto post_threads;
634 	for (n = 1; n <= ncpus; ++n) {
635 		globaldata_t rgd;
636 		int nid;
637 
638 		nid = (origcpu + n) % ncpus;
639 		if ((smp_active_mask & (1 << nid)) == 0)
640 			continue;
641 		rgd = globaldata_find(nid);
642 		lwkt_setcpu_self(rgd);
643 		cpu_mb1();	/* CURRENT CPU HAS CHANGED */
644 
645 		TAILQ_FOREACH(td, &mycpu->gd_tdallq, td_allq) {
646 			if (td->td_proc)
647 				continue;
648 			switch (oidp->oid_number) {
649 			case KERN_PROC_PGRP:
650 			case KERN_PROC_TTY:
651 			case KERN_PROC_UID:
652 			case KERN_PROC_RUID:
653 				continue;
654 			default:
655 				break;
656 			}
657 			lwkt_hold(td);
658 			error = sysctl_out_proc(NULL, td, req, doingzomb);
659 			lwkt_rele(td);
660 			if (error)
661 				return (error);
662 		}
663 	}
664 post_threads:
665 	return (0);
666 }
667 
668 /*
669  * This sysctl allows a process to retrieve the argument list or process
670  * title for another process without groping around in the address space
671  * of the other process.  It also allow a process to set its own "process
672  * title to a string of its own choice.
673  */
674 static int
675 sysctl_kern_proc_args(SYSCTL_HANDLER_ARGS)
676 {
677 	int *name = (int*) arg1;
678 	u_int namelen = arg2;
679 	struct proc *p;
680 	struct pargs *pa;
681 	int error = 0;
682 	struct ucred *cr1 = curproc->p_ucred;
683 
684 	if (namelen != 1)
685 		return (EINVAL);
686 
687 	p = pfind((pid_t)name[0]);
688 	if (!p)
689 		return (0);
690 
691 	if ((!ps_argsopen) && p_trespass(cr1, p->p_ucred))
692 		return (0);
693 
694 	if (req->newptr && curproc != p)
695 		return (EPERM);
696 
697 	if (req->oldptr && p->p_args != NULL)
698 		error = SYSCTL_OUT(req, p->p_args->ar_args, p->p_args->ar_length);
699 	if (req->newptr == NULL)
700 		return (error);
701 
702 	if (p->p_args && --p->p_args->ar_ref == 0)
703 		FREE(p->p_args, M_PARGS);
704 	p->p_args = NULL;
705 
706 	if (req->newlen + sizeof(struct pargs) > ps_arg_cache_limit)
707 		return (error);
708 
709 	MALLOC(pa, struct pargs *, sizeof(struct pargs) + req->newlen,
710 	    M_PARGS, M_WAITOK);
711 	pa->ar_ref = 1;
712 	pa->ar_length = req->newlen;
713 	error = SYSCTL_IN(req, pa->ar_args, req->newlen);
714 	if (!error)
715 		p->p_args = pa;
716 	else
717 		FREE(pa, M_PARGS);
718 	return (error);
719 }
720 
721 SYSCTL_NODE(_kern, KERN_PROC, proc, CTLFLAG_RD,  0, "Process table");
722 
723 SYSCTL_PROC(_kern_proc, KERN_PROC_ALL, all, CTLFLAG_RD|CTLTYPE_STRUCT,
724 	0, 0, sysctl_kern_proc, "S,proc", "Return entire process table");
725 
726 SYSCTL_NODE(_kern_proc, KERN_PROC_PGRP, pgrp, CTLFLAG_RD,
727 	sysctl_kern_proc, "Process table");
728 
729 SYSCTL_NODE(_kern_proc, KERN_PROC_TTY, tty, CTLFLAG_RD,
730 	sysctl_kern_proc, "Process table");
731 
732 SYSCTL_NODE(_kern_proc, KERN_PROC_UID, uid, CTLFLAG_RD,
733 	sysctl_kern_proc, "Process table");
734 
735 SYSCTL_NODE(_kern_proc, KERN_PROC_RUID, ruid, CTLFLAG_RD,
736 	sysctl_kern_proc, "Process table");
737 
738 SYSCTL_NODE(_kern_proc, KERN_PROC_PID, pid, CTLFLAG_RD,
739 	sysctl_kern_proc, "Process table");
740 
741 SYSCTL_NODE(_kern_proc, KERN_PROC_ARGS, args, CTLFLAG_RW | CTLFLAG_ANYBODY,
742 	sysctl_kern_proc_args, "Process argument list");
743