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[dragonfly.git] / sys / kern / kern_fork.c
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1/*
2 * Copyright (c) 1982, 1986, 1989, 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 * 3. 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_fork.c 8.6 (Berkeley) 4/8/94
35 * $FreeBSD: src/sys/kern/kern_fork.c,v 1.72.2.14 2003/06/26 04:15:10 silby Exp $
36 */
37
38#include "opt_ktrace.h"
39
40#include <sys/param.h>
41#include <sys/systm.h>
42#include <sys/sysproto.h>
43#include <sys/filedesc.h>
44#include <sys/kernel.h>
45#include <sys/sysctl.h>
46#include <sys/malloc.h>
47#include <sys/proc.h>
48#include <sys/resourcevar.h>
49#include <sys/vnode.h>
50#include <sys/acct.h>
51#include <sys/ktrace.h>
52#include <sys/unistd.h>
53#include <sys/jail.h>
54#include <sys/lwp.h>
55
56#include <vm/vm.h>
57#include <sys/lock.h>
58#include <vm/pmap.h>
59#include <vm/vm_map.h>
60#include <vm/vm_extern.h>
61
62#include <sys/vmmeter.h>
63#include <sys/refcount.h>
64#include <sys/thread2.h>
65#include <sys/signal2.h>
66#include <sys/spinlock2.h>
67
68#include <sys/dsched.h>
69
70static MALLOC_DEFINE(M_ATFORK, "atfork", "atfork callback");
71static MALLOC_DEFINE(M_REAPER, "reaper", "process reapers");
72
73/*
74 * These are the stuctures used to create a callout list for things to do
75 * when forking a process
76 */
77struct forklist {
78 forklist_fn function;
79 TAILQ_ENTRY(forklist) next;
80};
81
82TAILQ_HEAD(forklist_head, forklist);
83static struct forklist_head fork_list = TAILQ_HEAD_INITIALIZER(fork_list);
84
85static struct lwp *lwp_fork(struct lwp *, struct proc *, int flags,
86 const cpumask_t *mask);
87static int lwp_create1(struct lwp_params *params,
88 const cpumask_t *mask);
89static struct lock reaper_lock = LOCK_INITIALIZER("reapgl", 0, 0);
90
91int forksleep; /* Place for fork1() to sleep on. */
92
93/*
94 * Red-Black tree support for LWPs
95 */
96
97static int
98rb_lwp_compare(struct lwp *lp1, struct lwp *lp2)
99{
100 if (lp1->lwp_tid < lp2->lwp_tid)
101 return(-1);
102 if (lp1->lwp_tid > lp2->lwp_tid)
103 return(1);
104 return(0);
105}
106
107RB_GENERATE2(lwp_rb_tree, lwp, u.lwp_rbnode, rb_lwp_compare, lwpid_t, lwp_tid);
108
109/*
110 * When forking, memory underpinning umtx-supported mutexes may be set
111 * COW causing the physical address to change. We must wakeup any threads
112 * blocked on the physical address to allow them to re-resolve their VM.
113 *
114 * (caller is holding p->p_token)
115 */
116static void
117wake_umtx_threads(struct proc *p1)
118{
119 struct lwp *lp;
120 struct thread *td;
121
122 RB_FOREACH(lp, lwp_rb_tree, &p1->p_lwp_tree) {
123 td = lp->lwp_thread;
124 if (td && (td->td_flags & TDF_TSLEEPQ) &&
125 (td->td_wdomain & PDOMAIN_MASK) == PDOMAIN_UMTX) {
126 wakeup_domain(td->td_wchan, PDOMAIN_UMTX);
127 }
128 }
129}
130
131/*
132 * fork() system call
133 */
134int
135sys_fork(struct fork_args *uap)
136{
137 struct lwp *lp = curthread->td_lwp;
138 struct proc *p2;
139 int error;
140
141 error = fork1(lp, RFFDG | RFPROC | RFPGLOCK, &p2);
142 if (error == 0) {
143 PHOLD(p2);
144 start_forked_proc(lp, p2);
145 uap->sysmsg_fds[0] = p2->p_pid;
146 uap->sysmsg_fds[1] = 0;
147 PRELE(p2);
148 }
149 return error;
150}
151
152/*
153 * vfork() system call
154 */
155int
156sys_vfork(struct vfork_args *uap)
157{
158 struct lwp *lp = curthread->td_lwp;
159 struct proc *p2;
160 int error;
161
162 error = fork1(lp, RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK, &p2);
163 if (error == 0) {
164 PHOLD(p2);
165 start_forked_proc(lp, p2);
166 uap->sysmsg_fds[0] = p2->p_pid;
167 uap->sysmsg_fds[1] = 0;
168 PRELE(p2);
169 }
170 return error;
171}
172
173/*
174 * Handle rforks. An rfork may (1) operate on the current process without
175 * creating a new, (2) create a new process that shared the current process's
176 * vmspace, signals, and/or descriptors, or (3) create a new process that does
177 * not share these things (normal fork).
178 *
179 * Note that we only call start_forked_proc() if a new process is actually
180 * created.
181 *
182 * rfork { int flags }
183 */
184int
185sys_rfork(struct rfork_args *uap)
186{
187 struct lwp *lp = curthread->td_lwp;
188 struct proc *p2;
189 int error;
190
191 if ((uap->flags & RFKERNELONLY) != 0)
192 return (EINVAL);
193
194 error = fork1(lp, uap->flags | RFPGLOCK, &p2);
195 if (error == 0) {
196 if (p2) {
197 PHOLD(p2);
198 start_forked_proc(lp, p2);
199 uap->sysmsg_fds[0] = p2->p_pid;
200 uap->sysmsg_fds[1] = 0;
201 PRELE(p2);
202 } else {
203 uap->sysmsg_fds[0] = 0;
204 uap->sysmsg_fds[1] = 0;
205 }
206 }
207 return error;
208}
209
210static int
211lwp_create1(struct lwp_params *uprm, const cpumask_t *umask)
212{
213 struct proc *p = curproc;
214 struct lwp *lp;
215 struct lwp_params params;
216 cpumask_t *mask = NULL, mask0;
217 int error;
218
219 error = copyin(uprm, &params, sizeof(params));
220 if (error)
221 goto fail2;
222
223 if (umask != NULL) {
224 error = copyin(umask, &mask0, sizeof(mask0));
225 if (error)
226 goto fail2;
227 CPUMASK_ANDMASK(mask0, smp_active_mask);
228 if (CPUMASK_TESTNZERO(mask0))
229 mask = &mask0;
230 }
231
232 lwkt_gettoken(&p->p_token);
233 plimit_lwp_fork(p); /* force exclusive access */
234 lp = lwp_fork(curthread->td_lwp, p, RFPROC | RFMEM, mask);
235 error = cpu_prepare_lwp(lp, &params);
236 if (error)
237 goto fail;
238 if (params.lwp_tid1 != NULL &&
239 (error = copyout(&lp->lwp_tid, params.lwp_tid1, sizeof(lp->lwp_tid))))
240 goto fail;
241 if (params.lwp_tid2 != NULL &&
242 (error = copyout(&lp->lwp_tid, params.lwp_tid2, sizeof(lp->lwp_tid))))
243 goto fail;
244
245 /*
246 * Now schedule the new lwp.
247 */
248 p->p_usched->resetpriority(lp);
249 crit_enter();
250 lp->lwp_stat = LSRUN;
251 p->p_usched->setrunqueue(lp);
252 crit_exit();
253 lwkt_reltoken(&p->p_token);
254
255 return (0);
256
257fail:
258 /*
259 * Make sure no one is using this lwp, before it is removed from
260 * the tree. If we didn't wait it here, lwp tree iteration with
261 * blocking operation would be broken.
262 */
263 while (lp->lwp_lock > 0)
264 tsleep(lp, 0, "lwpfail", 1);
265 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp);
266 --p->p_nthreads;
267 /* lwp_dispose expects an exited lwp, and a held proc */
268 atomic_set_int(&lp->lwp_mpflags, LWP_MP_WEXIT);
269 lp->lwp_thread->td_flags |= TDF_EXITING;
270 lwkt_remove_tdallq(lp->lwp_thread);
271 PHOLD(p);
272 biosched_done(lp->lwp_thread);
273 dsched_exit_thread(lp->lwp_thread);
274 lwp_dispose(lp);
275 lwkt_reltoken(&p->p_token);
276fail2:
277 return (error);
278}
279
280/*
281 * Low level thread create used by pthreads.
282 */
283int
284sys_lwp_create(struct lwp_create_args *uap)
285{
286
287 return (lwp_create1(uap->params, NULL));
288}
289
290int
291sys_lwp_create2(struct lwp_create2_args *uap)
292{
293
294 return (lwp_create1(uap->params, uap->mask));
295}
296
297int nprocs = 1; /* process 0 */
298
299int
300fork1(struct lwp *lp1, int flags, struct proc **procp)
301{
302 struct proc *p1 = lp1->lwp_proc;
303 struct proc *p2;
304 struct proc *pptr;
305 struct pgrp *p1grp;
306 struct pgrp *plkgrp;
307 struct sysreaper *reap;
308 uid_t uid;
309 int ok, error;
310 static int curfail = 0;
311 static struct timeval lastfail;
312 struct forklist *ep;
313 struct filedesc_to_leader *fdtol;
314
315 if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG))
316 return (EINVAL);
317
318 lwkt_gettoken(&p1->p_token);
319 plkgrp = NULL;
320 p2 = NULL;
321
322 /*
323 * Here we don't create a new process, but we divorce
324 * certain parts of a process from itself.
325 */
326 if ((flags & RFPROC) == 0) {
327 /*
328 * This kind of stunt does not work anymore if
329 * there are native threads (lwps) running
330 */
331 if (p1->p_nthreads != 1) {
332 error = EINVAL;
333 goto done;
334 }
335
336 vm_fork(p1, 0, flags);
337 if ((flags & RFMEM) == 0)
338 wake_umtx_threads(p1);
339
340 /*
341 * Close all file descriptors.
342 */
343 if (flags & RFCFDG) {
344 struct filedesc *fdtmp;
345 fdtmp = fdinit(p1);
346 fdfree(p1, fdtmp);
347 }
348
349 /*
350 * Unshare file descriptors (from parent.)
351 */
352 if (flags & RFFDG) {
353 if (p1->p_fd->fd_refcnt > 1) {
354 struct filedesc *newfd;
355 error = fdcopy(p1, &newfd);
356 if (error != 0) {
357 error = ENOMEM;
358 goto done;
359 }
360 fdfree(p1, newfd);
361 }
362 }
363 *procp = NULL;
364 error = 0;
365 goto done;
366 }
367
368 /*
369 * Interlock against process group signal delivery. If signals
370 * are pending after the interlock is obtained we have to restart
371 * the system call to process the signals. If we don't the child
372 * can miss a pgsignal (such as ^C) sent during the fork.
373 *
374 * We can't use CURSIG() here because it will process any STOPs
375 * and cause the process group lock to be held indefinitely. If
376 * a STOP occurs, the fork will be restarted after the CONT.
377 */
378 p1grp = p1->p_pgrp;
379 if ((flags & RFPGLOCK) && (plkgrp = p1->p_pgrp) != NULL) {
380 pgref(plkgrp);
381 lockmgr(&plkgrp->pg_lock, LK_SHARED);
382 if (CURSIG_NOBLOCK(lp1)) {
383 error = ERESTART;
384 goto done;
385 }
386 }
387
388 /*
389 * Although process entries are dynamically created, we still keep
390 * a global limit on the maximum number we will create. Don't allow
391 * a nonprivileged user to use the last ten processes; don't let root
392 * exceed the limit. The variable nprocs is the current number of
393 * processes, maxproc is the limit.
394 */
395 uid = lp1->lwp_thread->td_ucred->cr_ruid;
396 if ((nprocs >= maxproc - 10 && uid != 0) || nprocs >= maxproc) {
397 if (ppsratecheck(&lastfail, &curfail, 1))
398 kprintf("maxproc limit exceeded by uid %d, please "
399 "see tuning(7) and login.conf(5).\n", uid);
400 tsleep(&forksleep, 0, "fork", hz / 2);
401 error = EAGAIN;
402 goto done;
403 }
404
405 /*
406 * Increment the nprocs resource before blocking can occur. There
407 * are hard-limits as to the number of processes that can run.
408 */
409 atomic_add_int(&nprocs, 1);
410
411 /*
412 * Increment the count of procs running with this uid. This also
413 * applies to root.
414 */
415 ok = chgproccnt(lp1->lwp_thread->td_ucred->cr_ruidinfo, 1,
416 plimit_getadjvalue(RLIMIT_NPROC));
417 if (!ok) {
418 /*
419 * Back out the process count
420 */
421 atomic_add_int(&nprocs, -1);
422 if (ppsratecheck(&lastfail, &curfail, 1)) {
423 kprintf("maxproc limit of %jd "
424 "exceeded by \"%s\" uid %d, "
425 "please see tuning(7) and login.conf(5).\n",
426 plimit_getadjvalue(RLIMIT_NPROC),
427 p1->p_comm,
428 uid);
429 }
430 tsleep(&forksleep, 0, "fork", hz / 2);
431 error = EAGAIN;
432 goto done;
433 }
434
435 /*
436 * Allocate a new process, don't get fancy: zero the structure.
437 */
438 p2 = kmalloc(sizeof(struct proc), M_PROC, M_WAITOK|M_ZERO);
439
440 /*
441 * Core initialization. SIDL is a safety state that protects the
442 * partially initialized process once it starts getting hooked
443 * into system structures and becomes addressable.
444 *
445 * We must be sure to acquire p2->p_token as well, we must hold it
446 * once the process is on the allproc list to avoid things such
447 * as competing modifications to p_flags.
448 */
449 mycpu->gd_forkid += ncpus;
450 p2->p_forkid = mycpu->gd_forkid + mycpu->gd_cpuid;
451 p2->p_lasttid = 0; /* first tid will be 1 */
452 p2->p_stat = SIDL;
453
454 /*
455 * NOTE: Process 0 will not have a reaper, but process 1 (init) and
456 * all other processes always will.
457 */
458 if ((reap = p1->p_reaper) != NULL) {
459 reaper_hold(reap);
460 p2->p_reaper = reap;
461 } else {
462 p2->p_reaper = NULL;
463 }
464
465 RB_INIT(&p2->p_lwp_tree);
466 spin_init(&p2->p_spin, "procfork1");
467 lwkt_token_init(&p2->p_token, "proc");
468 lwkt_gettoken(&p2->p_token);
469 p2->p_uidpcpu = kmalloc(sizeof(*p2->p_uidpcpu) * ncpus,
470 M_SUBPROC, M_WAITOK | M_ZERO);
471
472 /*
473 * Setup linkage for kernel based threading XXX lwp. Also add the
474 * process to the allproclist.
475 *
476 * The process structure is addressable after this point.
477 */
478 if (flags & RFTHREAD) {
479 p2->p_peers = p1->p_peers;
480 p1->p_peers = p2;
481 p2->p_leader = p1->p_leader;
482 } else {
483 p2->p_leader = p2;
484 }
485 proc_add_allproc(p2);
486
487 /*
488 * Initialize the section which is copied verbatim from the parent.
489 */
490 bcopy(&p1->p_startcopy, &p2->p_startcopy,
491 ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy));
492
493 /*
494 * Duplicate sub-structures as needed. Increase reference counts
495 * on shared objects.
496 *
497 * NOTE: because we are now on the allproc list it is possible for
498 * other consumers to gain temporary references to p2
499 * (p2->p_lock can change).
500 */
501 if (p1->p_flags & P_PROFIL)
502 startprofclock(p2);
503 p2->p_ucred = crhold(lp1->lwp_thread->td_ucred);
504
505 if (jailed(p2->p_ucred))
506 p2->p_flags |= P_JAILED;
507
508 if (p2->p_args)
509 refcount_acquire(&p2->p_args->ar_ref);
510
511 p2->p_usched = p1->p_usched;
512 /* XXX: verify copy of the secondary iosched stuff */
513 dsched_enter_proc(p2);
514
515 if (flags & RFSIGSHARE) {
516 p2->p_sigacts = p1->p_sigacts;
517 refcount_acquire(&p2->p_sigacts->ps_refcnt);
518 } else {
519 p2->p_sigacts = kmalloc(sizeof(*p2->p_sigacts),
520 M_SUBPROC, M_WAITOK);
521 bcopy(p1->p_sigacts, p2->p_sigacts, sizeof(*p2->p_sigacts));
522 refcount_init(&p2->p_sigacts->ps_refcnt, 1);
523 }
524 if (flags & RFLINUXTHPN)
525 p2->p_sigparent = SIGUSR1;
526 else
527 p2->p_sigparent = SIGCHLD;
528
529 /* bump references to the text vnode (for procfs) */
530 p2->p_textvp = p1->p_textvp;
531 if (p2->p_textvp)
532 vref(p2->p_textvp);
533
534 /* copy namecache handle to the text file */
535 if (p1->p_textnch.mount)
536 cache_copy(&p1->p_textnch, &p2->p_textnch);
537
538 /*
539 * Handle file descriptors
540 */
541 if (flags & RFCFDG) {
542 p2->p_fd = fdinit(p1);
543 fdtol = NULL;
544 } else if (flags & RFFDG) {
545 error = fdcopy(p1, &p2->p_fd);
546 if (error != 0) {
547 error = ENOMEM;
548 goto done;
549 }
550 fdtol = NULL;
551 } else {
552 p2->p_fd = fdshare(p1);
553 if (p1->p_fdtol == NULL) {
554 p1->p_fdtol = filedesc_to_leader_alloc(NULL,
555 p1->p_leader);
556 }
557 if ((flags & RFTHREAD) != 0) {
558 /*
559 * Shared file descriptor table and
560 * shared process leaders.
561 */
562 fdtol = p1->p_fdtol;
563 fdtol->fdl_refcount++;
564 } else {
565 /*
566 * Shared file descriptor table, and
567 * different process leaders
568 */
569 fdtol = filedesc_to_leader_alloc(p1->p_fdtol, p2);
570 }
571 }
572 p2->p_fdtol = fdtol;
573 p2->p_limit = plimit_fork(p1);
574
575 /*
576 * Adjust depth for resource downscaling
577 */
578 if ((p2->p_depth & 31) != 31)
579 ++p2->p_depth;
580
581 /*
582 * Preserve some more flags in subprocess. P_PROFIL has already
583 * been preserved.
584 */
585 p2->p_flags |= p1->p_flags & P_SUGID;
586 if (p1->p_session->s_ttyvp != NULL && (p1->p_flags & P_CONTROLT))
587 p2->p_flags |= P_CONTROLT;
588 if (flags & RFPPWAIT) {
589 p2->p_flags |= P_PPWAIT;
590 if (p1->p_upmap)
591 atomic_add_int(&p1->p_upmap->invfork, 1);
592 }
593
594 /*
595 * Inherit the virtual kernel structure (allows a virtual kernel
596 * to fork to simulate multiple cpus).
597 */
598 if (p1->p_vkernel)
599 vkernel_inherit(p1, p2);
600
601 /*
602 * Once we are on a pglist we may receive signals. XXX we might
603 * race a ^C being sent to the process group by not receiving it
604 * at all prior to this line.
605 */
606 pgref(p1grp);
607 lwkt_gettoken(&p1grp->pg_token);
608 LIST_INSERT_AFTER(p1, p2, p_pglist);
609 lwkt_reltoken(&p1grp->pg_token);
610
611 /*
612 * Attach the new process to its parent.
613 *
614 * If RFNOWAIT is set, the newly created process becomes a child
615 * of the reaper (typically init). This effectively disassociates
616 * the child from the parent.
617 *
618 * Temporarily hold pptr for the RFNOWAIT case to avoid ripouts.
619 */
620 if (flags & RFNOWAIT) {
621 pptr = reaper_get(reap);
622 if (pptr == NULL) {
623 pptr = initproc;
624 PHOLD(pptr);
625 }
626 } else {
627 pptr = p1;
628 }
629 p2->p_pptr = pptr;
630 p2->p_ppid = pptr->p_pid;
631 LIST_INIT(&p2->p_children);
632
633 lwkt_gettoken(&pptr->p_token);
634 LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling);
635 lwkt_reltoken(&pptr->p_token);
636
637 if (flags & RFNOWAIT)
638 PRELE(pptr);
639
640 varsymset_init(&p2->p_varsymset, &p1->p_varsymset);
641 callout_init_mp(&p2->p_ithandle);
642
643#ifdef KTRACE
644 /*
645 * Copy traceflag and tracefile if enabled. If not inherited,
646 * these were zeroed above but we still could have a trace race
647 * so make sure p2's p_tracenode is NULL.
648 */
649 if ((p1->p_traceflag & KTRFAC_INHERIT) && p2->p_tracenode == NULL) {
650 p2->p_traceflag = p1->p_traceflag;
651 p2->p_tracenode = ktrinherit(p1->p_tracenode);
652 }
653#endif
654
655 /*
656 * This begins the section where we must prevent the parent
657 * from being swapped.
658 *
659 * Gets PRELE'd in the caller in start_forked_proc().
660 */
661 PHOLD(p1);
662
663 vm_fork(p1, p2, flags);
664 if ((flags & RFMEM) == 0)
665 wake_umtx_threads(p1);
666
667 /*
668 * Create the first lwp associated with the new proc.
669 * It will return via a different execution path later, directly
670 * into userland, after it was put on the runq by
671 * start_forked_proc().
672 */
673 lwp_fork(lp1, p2, flags, NULL);
674
675 if (flags == (RFFDG | RFPROC | RFPGLOCK)) {
676 mycpu->gd_cnt.v_forks++;
677 mycpu->gd_cnt.v_forkpages += btoc(p2->p_vmspace->vm_dsize) +
678 btoc(p2->p_vmspace->vm_ssize);
679 } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK)) {
680 mycpu->gd_cnt.v_vforks++;
681 mycpu->gd_cnt.v_vforkpages += btoc(p2->p_vmspace->vm_dsize) +
682 btoc(p2->p_vmspace->vm_ssize);
683 } else if (p1 == &proc0) {
684 mycpu->gd_cnt.v_kthreads++;
685 mycpu->gd_cnt.v_kthreadpages += btoc(p2->p_vmspace->vm_dsize) +
686 btoc(p2->p_vmspace->vm_ssize);
687 } else {
688 mycpu->gd_cnt.v_rforks++;
689 mycpu->gd_cnt.v_rforkpages += btoc(p2->p_vmspace->vm_dsize) +
690 btoc(p2->p_vmspace->vm_ssize);
691 }
692
693 /*
694 * Both processes are set up, now check if any loadable modules want
695 * to adjust anything.
696 * What if they have an error? XXX
697 */
698 TAILQ_FOREACH(ep, &fork_list, next) {
699 (*ep->function)(p1, p2, flags);
700 }
701
702 /*
703 * Set the start time. Note that the process is not runnable. The
704 * caller is responsible for making it runnable.
705 */
706 microtime(&p2->p_start);
707 p2->p_acflag = AFORK;
708
709 /*
710 * tell any interested parties about the new process
711 */
712 KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid);
713
714 /*
715 * Return child proc pointer to parent.
716 */
717 *procp = p2;
718 error = 0;
719done:
720 if (p2)
721 lwkt_reltoken(&p2->p_token);
722 lwkt_reltoken(&p1->p_token);
723 if (plkgrp) {
724 lockmgr(&plkgrp->pg_lock, LK_RELEASE);
725 pgrel(plkgrp);
726 }
727 return (error);
728}
729
730static struct lwp *
731lwp_fork(struct lwp *origlp, struct proc *destproc, int flags,
732 const cpumask_t *mask)
733{
734 globaldata_t gd = mycpu;
735 struct lwp *lp;
736 struct thread *td;
737
738 lp = kmalloc(sizeof(struct lwp), M_LWP, M_WAITOK|M_ZERO);
739
740 lp->lwp_proc = destproc;
741 lp->lwp_vmspace = destproc->p_vmspace;
742 lp->lwp_stat = LSRUN;
743 bcopy(&origlp->lwp_startcopy, &lp->lwp_startcopy,
744 (unsigned) ((caddr_t)&lp->lwp_endcopy -
745 (caddr_t)&lp->lwp_startcopy));
746 if (mask != NULL)
747 lp->lwp_cpumask = *mask;
748
749 /*
750 * Reset the sigaltstack if memory is shared, otherwise inherit
751 * it.
752 */
753 if (flags & RFMEM) {
754 lp->lwp_sigstk.ss_flags = SS_DISABLE;
755 lp->lwp_sigstk.ss_size = 0;
756 lp->lwp_sigstk.ss_sp = NULL;
757 lp->lwp_flags &= ~LWP_ALTSTACK;
758 } else {
759 lp->lwp_flags |= origlp->lwp_flags & LWP_ALTSTACK;
760 }
761
762 /*
763 * Set cpbase to the last timeout that occured (not the upcoming
764 * timeout).
765 *
766 * A critical section is required since a timer IPI can update
767 * scheduler specific data.
768 */
769 crit_enter();
770 lp->lwp_cpbase = gd->gd_schedclock.time - gd->gd_schedclock.periodic;
771 destproc->p_usched->heuristic_forking(origlp, lp);
772 crit_exit();
773 CPUMASK_ANDMASK(lp->lwp_cpumask, usched_mastermask);
774 lwkt_token_init(&lp->lwp_token, "lwp_token");
775 spin_init(&lp->lwp_spin, "lwptoken");
776
777 /*
778 * Assign the thread to the current cpu to begin with so we
779 * can manipulate it.
780 */
781 td = lwkt_alloc_thread(NULL, LWKT_THREAD_STACK, gd->gd_cpuid, 0);
782 lp->lwp_thread = td;
783 td->td_wakefromcpu = gd->gd_cpuid;
784 td->td_ucred = crhold(destproc->p_ucred);
785 td->td_proc = destproc;
786 td->td_lwp = lp;
787 td->td_switch = cpu_heavy_switch;
788#ifdef NO_LWKT_SPLIT_USERPRI
789 lwkt_setpri(td, TDPRI_USER_NORM);
790#else
791 lwkt_setpri(td, TDPRI_KERN_USER);
792#endif
793 lwkt_set_comm(td, "%s", destproc->p_comm);
794
795 /*
796 * cpu_fork will copy and update the pcb, set up the kernel stack,
797 * and make the child ready to run.
798 */
799 cpu_fork(origlp, lp, flags);
800 kqueue_init(&lp->lwp_kqueue, destproc->p_fd);
801
802 /*
803 * Assign a TID to the lp. Loop until the insert succeeds (returns
804 * NULL).
805 *
806 * If we are in a vfork assign the same TID as the lwp that did the
807 * vfork(). This way if the user program messes around with
808 * pthread calls inside the vfork(), it will operate like an
809 * extension of the (blocked) parent. Also note that since the
810 * address space is being shared, insofar as pthreads is concerned,
811 * the code running in the vfork() is part of the original process.
812 */
813 if (flags & RFPPWAIT) {
814 lp->lwp_tid = origlp->lwp_tid - 1;
815 } else {
816 lp->lwp_tid = destproc->p_lasttid;
817 }
818
819 /*
820 * Leave 2 bits open so the pthreads library can optimize locks
821 * by combining the TID with a few LOck-related flags.
822 */
823 do {
824 if (lp->lwp_tid == 0 || lp->lwp_tid == 0x3FFFFFFF)
825 lp->lwp_tid = 1;
826 else
827 ++lp->lwp_tid;
828 } while (lwp_rb_tree_RB_INSERT(&destproc->p_lwp_tree, lp) != NULL);
829
830 destproc->p_lasttid = lp->lwp_tid;
831 destproc->p_nthreads++;
832
833 /*
834 * This flag is set and never cleared. It means that the process
835 * was threaded at some point. Used to improve exit performance.
836 */
837 pmap_maybethreaded(&destproc->p_vmspace->vm_pmap);
838 destproc->p_flags |= P_MAYBETHREADED;
839
840 return (lp);
841}
842
843/*
844 * The next two functionms are general routines to handle adding/deleting
845 * items on the fork callout list.
846 *
847 * at_fork():
848 * Take the arguments given and put them onto the fork callout list,
849 * However first make sure that it's not already there.
850 * Returns 0 on success or a standard error number.
851 */
852int
853at_fork(forklist_fn function)
854{
855 struct forklist *ep;
856
857#ifdef INVARIANTS
858 /* let the programmer know if he's been stupid */
859 if (rm_at_fork(function)) {
860 kprintf("WARNING: fork callout entry (%p) already present\n",
861 function);
862 }
863#endif
864 ep = kmalloc(sizeof(*ep), M_ATFORK, M_WAITOK|M_ZERO);
865 ep->function = function;
866 TAILQ_INSERT_TAIL(&fork_list, ep, next);
867 return (0);
868}
869
870/*
871 * Scan the exit callout list for the given item and remove it..
872 * Returns the number of items removed (0 or 1)
873 */
874int
875rm_at_fork(forklist_fn function)
876{
877 struct forklist *ep;
878
879 TAILQ_FOREACH(ep, &fork_list, next) {
880 if (ep->function == function) {
881 TAILQ_REMOVE(&fork_list, ep, next);
882 kfree(ep, M_ATFORK);
883 return(1);
884 }
885 }
886 return (0);
887}
888
889/*
890 * Add a forked process to the run queue after any remaining setup, such
891 * as setting the fork handler, has been completed.
892 *
893 * p2 is held by the caller.
894 */
895void
896start_forked_proc(struct lwp *lp1, struct proc *p2)
897{
898 struct lwp *lp2 = ONLY_LWP_IN_PROC(p2);
899 int pflags;
900
901 /*
902 * Move from SIDL to RUN queue, and activate the process's thread.
903 * Activation of the thread effectively makes the process "a"
904 * current process, so we do not setrunqueue().
905 *
906 * YYY setrunqueue works here but we should clean up the trampoline
907 * code so we just schedule the LWKT thread and let the trampoline
908 * deal with the userland scheduler on return to userland.
909 */
910 KASSERT(p2->p_stat == SIDL,
911 ("cannot start forked process, bad status: %p", p2));
912 p2->p_usched->resetpriority(lp2);
913 crit_enter();
914 p2->p_stat = SACTIVE;
915 lp2->lwp_stat = LSRUN;
916 p2->p_usched->setrunqueue(lp2);
917 crit_exit();
918
919 /*
920 * Now can be swapped.
921 */
922 PRELE(lp1->lwp_proc);
923
924 /*
925 * Preserve synchronization semantics of vfork. P_PPWAIT is set in
926 * the child until it has retired the parent's resources. The parent
927 * must wait for the flag to be cleared by the child.
928 *
929 * Interlock the flag/tsleep with atomic ops to avoid unnecessary
930 * p_token conflicts.
931 *
932 * XXX Is this use of an atomic op on a field that is not normally
933 * manipulated with atomic ops ok?
934 */
935 while ((pflags = p2->p_flags) & P_PPWAIT) {
936 cpu_ccfence();
937 tsleep_interlock(lp1->lwp_proc, 0);
938 if (atomic_cmpset_int(&p2->p_flags, pflags, pflags))
939 tsleep(lp1->lwp_proc, PINTERLOCKED, "ppwait", 0);
940 }
941}
942
943/*
944 * procctl (idtype_t idtype, id_t id, int cmd, void *arg)
945 */
946int
947sys_procctl(struct procctl_args *uap)
948{
949 struct proc *p = curproc;
950 struct proc *p2;
951 struct sysreaper *reap;
952 union reaper_info udata;
953 int error;
954
955 if (uap->idtype != P_PID || uap->id != (id_t)p->p_pid)
956 return EINVAL;
957
958 switch(uap->cmd) {
959 case PROC_REAP_ACQUIRE:
960 lwkt_gettoken(&p->p_token);
961 reap = kmalloc(sizeof(*reap), M_REAPER, M_WAITOK|M_ZERO);
962 if (p->p_reaper == NULL || p->p_reaper->p != p) {
963 reaper_init(p, reap);
964 error = 0;
965 } else {
966 kfree(reap, M_REAPER);
967 error = EALREADY;
968 }
969 lwkt_reltoken(&p->p_token);
970 break;
971 case PROC_REAP_RELEASE:
972 lwkt_gettoken(&p->p_token);
973release_again:
974 reap = p->p_reaper;
975 KKASSERT(reap != NULL);
976 if (reap->p == p) {
977 reaper_hold(reap); /* in case of thread race */
978 lockmgr(&reap->lock, LK_EXCLUSIVE);
979 if (reap->p != p) {
980 lockmgr(&reap->lock, LK_RELEASE);
981 reaper_drop(reap);
982 goto release_again;
983 }
984 reap->p = NULL;
985 p->p_reaper = reap->parent;
986 if (p->p_reaper)
987 reaper_hold(p->p_reaper);
988 lockmgr(&reap->lock, LK_RELEASE);
989 reaper_drop(reap); /* our ref */
990 reaper_drop(reap); /* old p_reaper ref */
991 error = 0;
992 } else {
993 error = ENOTCONN;
994 }
995 lwkt_reltoken(&p->p_token);
996 break;
997 case PROC_REAP_STATUS:
998 bzero(&udata, sizeof(udata));
999 lwkt_gettoken_shared(&p->p_token);
1000 if ((reap = p->p_reaper) != NULL && reap->p == p) {
1001 udata.status.flags = reap->flags;
1002 udata.status.refs = reap->refs - 1; /* minus ours */
1003 }
1004 p2 = LIST_FIRST(&p->p_children);
1005 udata.status.pid_head = p2 ? p2->p_pid : -1;
1006 lwkt_reltoken(&p->p_token);
1007
1008 if (uap->data) {
1009 error = copyout(&udata, uap->data,
1010 sizeof(udata.status));
1011 } else {
1012 error = 0;
1013 }
1014 break;
1015 default:
1016 error = EINVAL;
1017 break;
1018 }
1019 return error;
1020}
1021
1022/*
1023 * Bump ref on reaper, preventing destruction
1024 */
1025void
1026reaper_hold(struct sysreaper *reap)
1027{
1028 KKASSERT(reap->refs > 0);
1029 refcount_acquire(&reap->refs);
1030}
1031
1032/*
1033 * Drop ref on reaper, destroy the structure on the 1->0
1034 * transition and loop on the parent.
1035 */
1036void
1037reaper_drop(struct sysreaper *next)
1038{
1039 struct sysreaper *reap;
1040
1041 while ((reap = next) != NULL) {
1042 if (refcount_release(&reap->refs)) {
1043 next = reap->parent;
1044 KKASSERT(reap->p == NULL);
1045 lockmgr(&reaper_lock, LK_EXCLUSIVE);
1046 reap->parent = NULL;
1047 kfree(reap, M_REAPER);
1048 lockmgr(&reaper_lock, LK_RELEASE);
1049 } else {
1050 next = NULL;
1051 }
1052 }
1053}
1054
1055/*
1056 * Initialize a static or newly allocated reaper structure
1057 */
1058void
1059reaper_init(struct proc *p, struct sysreaper *reap)
1060{
1061 reap->parent = p->p_reaper;
1062 reap->p = p;
1063 if (p == initproc) {
1064 reap->flags = REAPER_STAT_OWNED | REAPER_STAT_REALINIT;
1065 reap->refs = 2;
1066 } else {
1067 reap->flags = REAPER_STAT_OWNED;
1068 reap->refs = 1;
1069 }
1070 lockinit(&reap->lock, "subrp", 0, 0);
1071 cpu_sfence();
1072 p->p_reaper = reap;
1073}
1074
1075/*
1076 * Called with p->p_token held during exit.
1077 *
1078 * This is a bit simpler than RELEASE because there are no threads remaining
1079 * to race. We only release if we own the reaper, the exit code will handle
1080 * the final p_reaper release.
1081 */
1082struct sysreaper *
1083reaper_exit(struct proc *p)
1084{
1085 struct sysreaper *reap;
1086
1087 /*
1088 * Release acquired reaper
1089 */
1090 if ((reap = p->p_reaper) != NULL && reap->p == p) {
1091 lockmgr(&reap->lock, LK_EXCLUSIVE);
1092 p->p_reaper = reap->parent;
1093 if (p->p_reaper)
1094 reaper_hold(p->p_reaper);
1095 reap->p = NULL;
1096 lockmgr(&reap->lock, LK_RELEASE);
1097 reaper_drop(reap);
1098 }
1099
1100 /*
1101 * Return and clear reaper (caller is holding p_token for us)
1102 * (reap->p does not equal p). Caller must drop it.
1103 */
1104 if ((reap = p->p_reaper) != NULL) {
1105 p->p_reaper = NULL;
1106 }
1107 return reap;
1108}
1109
1110/*
1111 * Return a held (PHOLD) process representing the reaper for process (p).
1112 * NULL should not normally be returned. Caller should PRELE() the returned
1113 * reaper process when finished.
1114 *
1115 * Remove dead internal nodes while we are at it.
1116 *
1117 * Process (p)'s token must be held on call.
1118 * The returned process's token is NOT acquired by this routine.
1119 */
1120struct proc *
1121reaper_get(struct sysreaper *reap)
1122{
1123 struct sysreaper *next;
1124 struct proc *reproc;
1125
1126 if (reap == NULL)
1127 return NULL;
1128
1129 /*
1130 * Extra hold for loop
1131 */
1132 reaper_hold(reap);
1133
1134 while (reap) {
1135 lockmgr(&reap->lock, LK_SHARED);
1136 if (reap->p) {
1137 /*
1138 * Probable reaper
1139 */
1140 if (reap->p) {
1141 reproc = reap->p;
1142 PHOLD(reproc);
1143 lockmgr(&reap->lock, LK_RELEASE);
1144 reaper_drop(reap);
1145 return reproc;
1146 }
1147
1148 /*
1149 * Raced, try again
1150 */
1151 lockmgr(&reap->lock, LK_RELEASE);
1152 continue;
1153 }
1154
1155 /*
1156 * Traverse upwards in the reaper topology, destroy
1157 * dead internal nodes when possible.
1158 *
1159 * NOTE: Our ref on next means that a dead node should
1160 * have 2 (ours and reap->parent's).
1161 */
1162 next = reap->parent;
1163 while (next) {
1164 reaper_hold(next);
1165 if (next->refs == 2 && next->p == NULL) {
1166 lockmgr(&reap->lock, LK_RELEASE);
1167 lockmgr(&reap->lock, LK_EXCLUSIVE);
1168 if (next->refs == 2 &&
1169 reap->parent == next &&
1170 next->p == NULL) {
1171 /*
1172 * reap->parent inherits ref from next.
1173 */
1174 reap->parent = next->parent;
1175 next->parent = NULL;
1176 reaper_drop(next); /* ours */
1177 reaper_drop(next); /* old parent */
1178 next = reap->parent;
1179 continue; /* possible chain */
1180 }
1181 }
1182 break;
1183 }
1184 lockmgr(&reap->lock, LK_RELEASE);
1185 reaper_drop(reap);
1186 reap = next;
1187 }
1188 return NULL;
1189}
1190
1191/*
1192 * Test that the sender is allowed to send a signal to the target.
1193 * The sender process is assumed to have a stable reaper. The
1194 * target can be e.g. from a scan callback.
1195 *
1196 * Target cannot be the reaper process itself unless reaper_ok is specified,
1197 * or sender == target.
1198 */
1199int
1200reaper_sigtest(struct proc *sender, struct proc *target, int reaper_ok)
1201{
1202 struct sysreaper *sreap;
1203 struct sysreaper *reap;
1204 int r;
1205
1206 sreap = sender->p_reaper;
1207 if (sreap == NULL)
1208 return 1;
1209
1210 if (sreap == target->p_reaper) {
1211 if (sreap->p == target && sreap->p != sender && reaper_ok == 0)
1212 return 0;
1213 return 1;
1214 }
1215 lockmgr(&reaper_lock, LK_SHARED);
1216 r = 0;
1217 for (reap = target->p_reaper; reap; reap = reap->parent) {
1218 if (sreap == reap) {
1219 if (sreap->p != target || reaper_ok)
1220 r = 1;
1221 break;
1222 }
1223 }
1224 lockmgr(&reaper_lock, LK_RELEASE);
1225
1226 return r;
1227}