kernel - use new td_ucred in numerous places
[dragonfly.git] / sys / kern / kern_fork.c
CommitLineData
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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. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the University of
21 * California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * @(#)kern_fork.c 8.6 (Berkeley) 4/8/94
5bc7cd8d 39 * $FreeBSD: src/sys/kern/kern_fork.c,v 1.72.2.14 2003/06/26 04:15:10 silby Exp $
f6c36234 40 * $DragonFly: src/sys/kern/kern_fork.c,v 1.77 2008/05/18 20:02:02 nth Exp $
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41 */
42
43#include "opt_ktrace.h"
44
45#include <sys/param.h>
46#include <sys/systm.h>
47#include <sys/sysproto.h>
48#include <sys/filedesc.h>
49#include <sys/kernel.h>
50#include <sys/sysctl.h>
51#include <sys/malloc.h>
52#include <sys/proc.h>
53#include <sys/resourcevar.h>
54#include <sys/vnode.h>
55#include <sys/acct.h>
56#include <sys/ktrace.h>
dfc1fc13
EN
57#include <sys/unistd.h>
58#include <sys/jail.h>
59#include <sys/caps.h>
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60
61#include <vm/vm.h>
62#include <sys/lock.h>
63#include <vm/pmap.h>
64#include <vm/vm_map.h>
65#include <vm/vm_extern.h>
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66
67#include <sys/vmmeter.h>
e43a034f 68#include <sys/thread2.h>
b1b4e5a6 69#include <sys/signal2.h>
8f1f6170 70#include <sys/spinlock2.h>
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71
72static MALLOC_DEFINE(M_ATFORK, "atfork", "atfork callback");
73
74/*
75 * These are the stuctures used to create a callout list for things to do
76 * when forking a process
77 */
78struct forklist {
79 forklist_fn function;
80 TAILQ_ENTRY(forklist) next;
81};
82
83TAILQ_HEAD(forklist_head, forklist);
84static struct forklist_head fork_list = TAILQ_HEAD_INITIALIZER(fork_list);
85
13d13d89
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86static struct lwp *lwp_fork(struct lwp *, struct proc *, int flags);
87
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88int forksleep; /* Place for fork1() to sleep on. */
89
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90/*
91 * Red-Black tree support for LWPs
92 */
93
94static int
95rb_lwp_compare(struct lwp *lp1, struct lwp *lp2)
96{
97 if (lp1->lwp_tid < lp2->lwp_tid)
98 return(-1);
99 if (lp1->lwp_tid > lp2->lwp_tid)
100 return(1);
101 return(0);
102}
103
104RB_GENERATE2(lwp_rb_tree, lwp, u.lwp_rbnode, rb_lwp_compare, lwpid_t, lwp_tid);
105
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106/*
107 * Fork system call
108 *
109 * MPALMOSTSAFE
110 */
984263bc 111int
753fd850 112sys_fork(struct fork_args *uap)
984263bc 113{
553ea3c8 114 struct lwp *lp = curthread->td_lwp;
984263bc 115 struct proc *p2;
41c20dac 116 int error;
984263bc 117
3919ced0 118 get_mplock();
167e6ecb 119 error = fork1(lp, RFFDG | RFPROC | RFPGLOCK, &p2);
984263bc 120 if (error == 0) {
553ea3c8 121 start_forked_proc(lp, p2);
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122 uap->sysmsg_fds[0] = p2->p_pid;
123 uap->sysmsg_fds[1] = 0;
984263bc 124 }
3919ced0 125 rel_mplock();
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126 return error;
127}
128
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129/*
130 * MPALMOSTSAFE
131 */
984263bc 132int
753fd850 133sys_vfork(struct vfork_args *uap)
984263bc 134{
553ea3c8 135 struct lwp *lp = curthread->td_lwp;
984263bc 136 struct proc *p2;
41c20dac 137 int error;
984263bc 138
3919ced0 139 get_mplock();
167e6ecb 140 error = fork1(lp, RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK, &p2);
984263bc 141 if (error == 0) {
553ea3c8 142 start_forked_proc(lp, p2);
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143 uap->sysmsg_fds[0] = p2->p_pid;
144 uap->sysmsg_fds[1] = 0;
984263bc 145 }
3919ced0 146 rel_mplock();
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147 return error;
148}
149
f61c1ff1
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150/*
151 * Handle rforks. An rfork may (1) operate on the current process without
152 * creating a new, (2) create a new process that shared the current process's
153 * vmspace, signals, and/or descriptors, or (3) create a new process that does
154 * not share these things (normal fork).
155 *
156 * Note that we only call start_forked_proc() if a new process is actually
157 * created.
158 *
159 * rfork { int flags }
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160 *
161 * MPALMOSTSAFE
f61c1ff1 162 */
984263bc 163int
753fd850 164sys_rfork(struct rfork_args *uap)
984263bc 165{
553ea3c8 166 struct lwp *lp = curthread->td_lwp;
984263bc 167 struct proc *p2;
41c20dac 168 int error;
984263bc 169
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170 if ((uap->flags & RFKERNELONLY) != 0)
171 return (EINVAL);
172
3919ced0 173 get_mplock();
167e6ecb 174 error = fork1(lp, uap->flags | RFPGLOCK, &p2);
984263bc 175 if (error == 0) {
f61c1ff1 176 if (p2)
553ea3c8 177 start_forked_proc(lp, p2);
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178 uap->sysmsg_fds[0] = p2 ? p2->p_pid : 0;
179 uap->sysmsg_fds[1] = 0;
984263bc 180 }
3919ced0 181 rel_mplock();
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182 return error;
183}
184
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185/*
186 * MPALMOSTSAFE
187 */
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188int
189sys_lwp_create(struct lwp_create_args *uap)
190{
191 struct proc *p = curproc;
192 struct lwp *lp;
193 struct lwp_params params;
194 int error;
195
196 error = copyin(uap->params, &params, sizeof(params));
197 if (error)
198 goto fail2;
199
3919ced0 200 get_mplock();
8f1f6170 201 plimit_lwp_fork(p); /* force exclusive access */
91bd9c1e
SS
202 lp = lwp_fork(curthread->td_lwp, p, RFPROC);
203 error = cpu_prepare_lwp(lp, &params);
204 if (params.tid1 != NULL &&
205 (error = copyout(&lp->lwp_tid, params.tid1, sizeof(lp->lwp_tid))))
206 goto fail;
207 if (params.tid2 != NULL &&
208 (error = copyout(&lp->lwp_tid, params.tid2, sizeof(lp->lwp_tid))))
209 goto fail;
210
211 /*
8f1f6170 212 * Now schedule the new lwp.
91bd9c1e
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213 */
214 p->p_usched->resetpriority(lp);
215 crit_enter();
216 lp->lwp_stat = LSRUN;
217 p->p_usched->setrunqueue(lp);
218 crit_exit();
3919ced0 219 rel_mplock();
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220
221 return (0);
222
223fail:
3e291793 224 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp);
0b26dde3 225 --p->p_nthreads;
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226 /* lwp_dispose expects an exited lwp, and a held proc */
227 lp->lwp_flag |= LWP_WEXIT;
228 lp->lwp_thread->td_flags |= TDF_EXITING;
229 PHOLD(p);
91bd9c1e 230 lwp_dispose(lp);
3919ced0 231 rel_mplock();
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232fail2:
233 return (error);
234}
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235
236int nprocs = 1; /* process 0 */
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237
238int
553ea3c8 239fork1(struct lwp *lp1, int flags, struct proc **procp)
984263bc 240{
553ea3c8 241 struct proc *p1 = lp1->lwp_proc;
984263bc 242 struct proc *p2, *pptr;
167e6ecb 243 struct pgrp *pgrp;
984263bc 244 uid_t uid;
167e6ecb 245 int ok, error;
51e64ff2 246 static int curfail = 0;
5bc7cd8d 247 static struct timeval lastfail;
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248 struct forklist *ep;
249 struct filedesc_to_leader *fdtol;
250
251 if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG))
252 return (EINVAL);
253
254 /*
255 * Here we don't create a new process, but we divorce
256 * certain parts of a process from itself.
257 */
258 if ((flags & RFPROC) == 0) {
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259 /*
260 * This kind of stunt does not work anymore if
261 * there are native threads (lwps) running
262 */
263 if (p1->p_nthreads != 1)
264 return (EINVAL);
265
266 vm_fork(p1, 0, flags);
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267
268 /*
269 * Close all file descriptors.
270 */
271 if (flags & RFCFDG) {
272 struct filedesc *fdtmp;
273 fdtmp = fdinit(p1);
0a4a9c77 274 fdfree(p1, fdtmp);
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275 }
276
277 /*
278 * Unshare file descriptors (from parent.)
279 */
280 if (flags & RFFDG) {
281 if (p1->p_fd->fd_refcnt > 1) {
282 struct filedesc *newfd;
283 newfd = fdcopy(p1);
0a4a9c77 284 fdfree(p1, newfd);
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285 }
286 }
287 *procp = NULL;
288 return (0);
289 }
290
291 /*
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292 * Interlock against process group signal delivery. If signals
293 * are pending after the interlock is obtained we have to restart
294 * the system call to process the signals. If we don't the child
295 * can miss a pgsignal (such as ^C) sent during the fork.
296 *
297 * We can't use CURSIG() here because it will process any STOPs
298 * and cause the process group lock to be held indefinitely. If
299 * a STOP occurs, the fork will be restarted after the CONT.
300 */
301 error = 0;
302 pgrp = NULL;
303 if ((flags & RFPGLOCK) && (pgrp = p1->p_pgrp) != NULL) {
304 lockmgr(&pgrp->pg_lock, LK_SHARED);
f6e73860 305 if (CURSIG_NOBLOCK(lp1)) {
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306 error = ERESTART;
307 goto done;
308 }
309 }
310
311 /*
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312 * Although process entries are dynamically created, we still keep
313 * a global limit on the maximum number we will create. Don't allow
314 * a nonprivileged user to use the last ten processes; don't let root
315 * exceed the limit. The variable nprocs is the current number of
316 * processes, maxproc is the limit.
317 */
9910d07b 318 uid = lp1->lwp_thread->td_ucred->cr_ruid;
984263bc 319 if ((nprocs >= maxproc - 10 && uid != 0) || nprocs >= maxproc) {
5bc7cd8d 320 if (ppsratecheck(&lastfail, &curfail, 1))
6ea70f76 321 kprintf("maxproc limit exceeded by uid %d, please "
5bc7cd8d 322 "see tuning(7) and login.conf(5).\n", uid);
377d4740 323 tsleep(&forksleep, 0, "fork", hz / 2);
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324 error = EAGAIN;
325 goto done;
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326 }
327 /*
328 * Increment the nprocs resource before blocking can occur. There
329 * are hard-limits as to the number of processes that can run.
330 */
331 nprocs++;
332
333 /*
334 * Increment the count of procs running with this uid. Don't allow
335 * a nonprivileged user to exceed their current limit.
336 */
9910d07b 337 ok = chgproccnt(lp1->lwp_thread->td_ucred->cr_ruidinfo, 1,
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338 (uid != 0) ? p1->p_rlimit[RLIMIT_NPROC].rlim_cur : 0);
339 if (!ok) {
340 /*
341 * Back out the process count
342 */
343 nprocs--;
5bc7cd8d 344 if (ppsratecheck(&lastfail, &curfail, 1))
6ea70f76 345 kprintf("maxproc limit exceeded by uid %d, please "
5bc7cd8d 346 "see tuning(7) and login.conf(5).\n", uid);
377d4740 347 tsleep(&forksleep, 0, "fork", hz / 2);
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348 error = EAGAIN;
349 goto done;
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MD
350 }
351
352 /* Allocate new proc. */
37733243 353 p2 = kmalloc(sizeof(struct proc), M_PROC, M_WAITOK|M_ZERO);
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354
355 /*
ef09c3ed 356 * Setup linkage for kernel based threading XXX lwp
984263bc 357 */
cb74210d 358 if (flags & RFTHREAD) {
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359 p2->p_peers = p1->p_peers;
360 p1->p_peers = p2;
361 p2->p_leader = p1->p_leader;
984263bc 362 } else {
51e64ff2 363 p2->p_leader = p2;
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MD
364 }
365
3e291793 366 RB_INIT(&p2->p_lwp_tree);
8f1f6170 367 spin_init(&p2->p_spin);
3e291793 368 p2->p_lasttid = -1; /* first tid will be 0 */
ef09c3ed 369
984263bc 370 /*
51e64ff2
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371 * Setting the state to SIDL protects the partially initialized
372 * process once it starts getting hooked into the rest of the system.
984263bc 373 */
51e64ff2
MD
374 p2->p_stat = SIDL;
375 proc_add_allproc(p2);
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376
377 /*
378 * Make a proc table entry for the new process.
f9fe34b6
SS
379 * The whole structure was zeroed above, so copy the section that is
380 * copied directly from the parent.
984263bc 381 */
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MD
382 bcopy(&p1->p_startcopy, &p2->p_startcopy,
383 (unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy));
384
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385 /*
386 * Duplicate sub-structures as needed.
387 * Increase reference counts on shared objects.
984263bc 388 */
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MD
389 if (p1->p_flag & P_PROFIL)
390 startprofclock(p2);
9910d07b 391 p2->p_ucred = crhold(lp1->lwp_thread->td_ucred);
0d355d3b 392 KKASSERT(p2->p_lock == 0);
984263bc 393
b40e316c 394 if (jailed(p2->p_ucred))
984263bc 395 p2->p_flag |= P_JAILED;
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MD
396
397 if (p2->p_args)
398 p2->p_args->ar_ref++;
399
13d13d89
SS
400 p2->p_usched = p1->p_usched;
401
984263bc 402 if (flags & RFSIGSHARE) {
b1b4e5a6
SS
403 p2->p_sigacts = p1->p_sigacts;
404 p2->p_sigacts->ps_refcnt++;
984263bc 405 } else {
b1b4e5a6 406 p2->p_sigacts = (struct sigacts *)kmalloc(sizeof(*p2->p_sigacts),
984263bc 407 M_SUBPROC, M_WAITOK);
b1b4e5a6
SS
408 bcopy(p1->p_sigacts, p2->p_sigacts, sizeof(*p2->p_sigacts));
409 p2->p_sigacts->ps_refcnt = 1;
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MD
410 }
411 if (flags & RFLINUXTHPN)
412 p2->p_sigparent = SIGUSR1;
413 else
414 p2->p_sigparent = SIGCHLD;
415
416 /* bump references to the text vnode (for procfs) */
417 p2->p_textvp = p1->p_textvp;
418 if (p2->p_textvp)
597aea93 419 vref(p2->p_textvp);
984263bc 420
0daa37a5
MD
421 /*
422 * Handle file descriptors
423 */
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MD
424 if (flags & RFCFDG) {
425 p2->p_fd = fdinit(p1);
426 fdtol = NULL;
427 } else if (flags & RFFDG) {
428 p2->p_fd = fdcopy(p1);
429 fdtol = NULL;
430 } else {
431 p2->p_fd = fdshare(p1);
432 if (p1->p_fdtol == NULL)
433 p1->p_fdtol =
434 filedesc_to_leader_alloc(NULL,
435 p1->p_leader);
436 if ((flags & RFTHREAD) != 0) {
437 /*
438 * Shared file descriptor table and
439 * shared process leaders.
440 */
441 fdtol = p1->p_fdtol;
442 fdtol->fdl_refcount++;
443 } else {
444 /*
445 * Shared file descriptor table, and
446 * different process leaders
447 */
98a7f915 448 fdtol = filedesc_to_leader_alloc(p1->p_fdtol, p2);
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MD
449 }
450 }
451 p2->p_fdtol = fdtol;
8f1f6170 452 p2->p_limit = plimit_fork(p1);
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453
454 /*
455 * Preserve some more flags in subprocess. P_PROFIL has already
456 * been preserved.
457 */
08f2f1bb 458 p2->p_flag |= p1->p_flag & P_SUGID;
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459 if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT)
460 p2->p_flag |= P_CONTROLT;
461 if (flags & RFPPWAIT)
462 p2->p_flag |= P_PPWAIT;
463
5fd012e0 464 /*
0daa37a5
MD
465 * Inherit the virtual kernel structure (allows a virtual kernel
466 * to fork to simulate multiple cpus).
467 */
4a22e893
MD
468 if (p1->p_vkernel)
469 vkernel_inherit(p1, p2);
0daa37a5
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470
471 /*
5fd012e0
MD
472 * Once we are on a pglist we may receive signals. XXX we might
473 * race a ^C being sent to the process group by not receiving it
474 * at all prior to this line.
475 */
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476 LIST_INSERT_AFTER(p1, p2, p_pglist);
477
478 /*
479 * Attach the new process to its parent.
480 *
481 * If RFNOWAIT is set, the newly created process becomes a child
482 * of init. This effectively disassociates the child from the
483 * parent.
484 */
485 if (flags & RFNOWAIT)
486 pptr = initproc;
487 else
488 pptr = p1;
489 p2->p_pptr = pptr;
490 LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling);
491 LIST_INIT(&p2->p_children);
98a7f915 492 varsymset_init(&p2->p_varsymset, &p1->p_varsymset);
8fbf9130 493 callout_init(&p2->p_ithandle);
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494
495#ifdef KTRACE
496 /*
497 * Copy traceflag and tracefile if enabled. If not inherited,
498 * these were zeroed above but we still could have a trace race
29f58392 499 * so make sure p2's p_tracenode is NULL.
984263bc 500 */
29f58392 501 if ((p1->p_traceflag & KTRFAC_INHERIT) && p2->p_tracenode == NULL) {
984263bc 502 p2->p_traceflag = p1->p_traceflag;
29f58392 503 p2->p_tracenode = ktrinherit(p1->p_tracenode);
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MD
504 }
505#endif
506
507 /*
984263bc
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508 * This begins the section where we must prevent the parent
509 * from being swapped.
13d13d89
SS
510 *
511 * Gets PRELE'd in the caller in start_forked_proc().
984263bc
MD
512 */
513 PHOLD(p1);
514
13d13d89
SS
515 vm_fork(p1, p2, flags);
516
984263bc 517 /*
13d13d89
SS
518 * Create the first lwp associated with the new proc.
519 * It will return via a different execution path later, directly
520 * into userland, after it was put on the runq by
521 * start_forked_proc().
984263bc 522 */
13d13d89 523 lwp_fork(lp1, p2, flags);
984263bc 524
6b72a0c2 525 if (flags == (RFFDG | RFPROC | RFPGLOCK)) {
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526 mycpu->gd_cnt.v_forks++;
527 mycpu->gd_cnt.v_forkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize;
6b72a0c2 528 } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK)) {
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529 mycpu->gd_cnt.v_vforks++;
530 mycpu->gd_cnt.v_vforkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize;
984263bc 531 } else if (p1 == &proc0) {
12e4aaff
MD
532 mycpu->gd_cnt.v_kthreads++;
533 mycpu->gd_cnt.v_kthreadpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize;
984263bc 534 } else {
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MD
535 mycpu->gd_cnt.v_rforks++;
536 mycpu->gd_cnt.v_rforkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize;
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MD
537 }
538
539 /*
540 * Both processes are set up, now check if any loadable modules want
541 * to adjust anything.
542 * What if they have an error? XXX
543 */
544 TAILQ_FOREACH(ep, &fork_list, next) {
545 (*ep->function)(p1, p2, flags);
546 }
547
548 /*
a77ac49d
MD
549 * Set the start time. Note that the process is not runnable. The
550 * caller is responsible for making it runnable.
984263bc 551 */
d9fa5f67 552 microtime(&p2->p_start);
984263bc 553 p2->p_acflag = AFORK;
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554
555 /*
556 * tell any interested parties about the new process
557 */
558 KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid);
559
560 /*
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561 * Return child proc pointer to parent.
562 */
563 *procp = p2;
167e6ecb
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564done:
565 if (pgrp)
566 lockmgr(&pgrp->pg_lock, LK_RELEASE);
567 return (error);
984263bc
MD
568}
569
13d13d89
SS
570static struct lwp *
571lwp_fork(struct lwp *origlp, struct proc *destproc, int flags)
572{
573 struct lwp *lp;
574 struct thread *td;
13d13d89 575
f6c36234 576 lp = kmalloc(sizeof(struct lwp), M_LWP, M_WAITOK|M_ZERO);
3e291793 577
13d13d89 578 lp->lwp_proc = destproc;
287ebb09 579 lp->lwp_vmspace = destproc->p_vmspace;
13d13d89 580 lp->lwp_stat = LSRUN;
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581 bcopy(&origlp->lwp_startcopy, &lp->lwp_startcopy,
582 (unsigned) ((caddr_t)&lp->lwp_endcopy -
583 (caddr_t)&lp->lwp_startcopy));
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584 lp->lwp_flag |= origlp->lwp_flag & LWP_ALTSTACK;
585 /*
586 * Set cpbase to the last timeout that occured (not the upcoming
587 * timeout).
588 *
589 * A critical section is required since a timer IPI can update
590 * scheduler specific data.
591 */
592 crit_enter();
593 lp->lwp_cpbase = mycpu->gd_schedclock.time -
594 mycpu->gd_schedclock.periodic;
595 destproc->p_usched->heuristic_forking(origlp, lp);
596 crit_exit();
a5ae2446 597 lp->lwp_cpumask &= usched_mastermask;
13d13d89 598
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599 /*
600 * Assign a TID to the lp. Loop until the insert succeeds (returns
601 * NULL).
602 */
603 lp->lwp_tid = destproc->p_lasttid;
604 do {
605 if (++lp->lwp_tid < 0)
606 lp->lwp_tid = 1;
607 } while (lwp_rb_tree_RB_INSERT(&destproc->p_lwp_tree, lp) != NULL);
608 destproc->p_lasttid = lp->lwp_tid;
609 destproc->p_nthreads++;
610
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611 td = lwkt_alloc_thread(NULL, LWKT_THREAD_STACK, -1, 0);
612 lp->lwp_thread = td;
613 td->td_proc = destproc;
614 td->td_lwp = lp;
615 td->td_switch = cpu_heavy_switch;
616#ifdef SMP
617 KKASSERT(td->td_mpcount == 1);
618#endif
619 lwkt_setpri(td, TDPRI_KERN_USER);
620 lwkt_set_comm(td, "%s", destproc->p_comm);
621
622 /*
623 * cpu_fork will copy and update the pcb, set up the kernel stack,
624 * and make the child ready to run.
625 */
626 cpu_fork(origlp, lp, flags);
627 caps_fork(origlp->lwp_thread, lp->lwp_thread);
628
629 return (lp);
630}
631
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632/*
633 * The next two functionms are general routines to handle adding/deleting
634 * items on the fork callout list.
635 *
636 * at_fork():
637 * Take the arguments given and put them onto the fork callout list,
638 * However first make sure that it's not already there.
639 * Returns 0 on success or a standard error number.
640 */
984263bc 641int
303c76d5 642at_fork(forklist_fn function)
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643{
644 struct forklist *ep;
645
646#ifdef INVARIANTS
647 /* let the programmer know if he's been stupid */
303c76d5 648 if (rm_at_fork(function)) {
6ea70f76 649 kprintf("WARNING: fork callout entry (%p) already present\n",
984263bc 650 function);
303c76d5 651 }
984263bc 652#endif
efda3bd0 653 ep = kmalloc(sizeof(*ep), M_ATFORK, M_WAITOK|M_ZERO);
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654 ep->function = function;
655 TAILQ_INSERT_TAIL(&fork_list, ep, next);
656 return (0);
657}
658
659/*
660 * Scan the exit callout list for the given item and remove it..
661 * Returns the number of items removed (0 or 1)
662 */
984263bc 663int
303c76d5 664rm_at_fork(forklist_fn function)
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665{
666 struct forklist *ep;
667
668 TAILQ_FOREACH(ep, &fork_list, next) {
669 if (ep->function == function) {
670 TAILQ_REMOVE(&fork_list, ep, next);
efda3bd0 671 kfree(ep, M_ATFORK);
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672 return(1);
673 }
674 }
675 return (0);
676}
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677
678/*
679 * Add a forked process to the run queue after any remaining setup, such
680 * as setting the fork handler, has been completed.
681 */
7d0bac62 682void
553ea3c8 683start_forked_proc(struct lwp *lp1, struct proc *p2)
7d0bac62 684{
08f2f1bb 685 struct lwp *lp2 = ONLY_LWP_IN_PROC(p2);
553ea3c8 686
7d0bac62 687 /*
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688 * Move from SIDL to RUN queue, and activate the process's thread.
689 * Activation of the thread effectively makes the process "a"
690 * current process, so we do not setrunqueue().
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691 *
692 * YYY setrunqueue works here but we should clean up the trampoline
693 * code so we just schedule the LWKT thread and let the trampoline
694 * deal with the userland scheduler on return to userland.
7d0bac62 695 */
553ea3c8 696 KASSERT(p2->p_stat == SIDL,
7d0bac62 697 ("cannot start forked process, bad status: %p", p2));
553ea3c8 698 p2->p_usched->resetpriority(lp2);
e43a034f 699 crit_enter();
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700 p2->p_stat = SACTIVE;
701 lp2->lwp_stat = LSRUN;
553ea3c8 702 p2->p_usched->setrunqueue(lp2);
e43a034f 703 crit_exit();
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704
705 /*
706 * Now can be swapped.
707 */
553ea3c8 708 PRELE(lp1->lwp_proc);
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709
710 /*
711 * Preserve synchronization semantics of vfork. If waiting for
712 * child to exec or exit, set P_PPWAIT on child, and sleep on our
713 * proc (in case of exit).
714 */
715 while (p2->p_flag & P_PPWAIT)
553ea3c8 716 tsleep(lp1->lwp_proc, 0, "ppwait", 0);
7d0bac62 717}