Fix a minor bug in the last commit. lwp_cpumask has to be in the LWP copy
[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 $
a60ccb85 40 * $DragonFly: src/sys/kern/kern_fork.c,v 1.51 2006/06/05 00:32:37 davidxu 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
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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>
66#include <vm/vm_zone.h>
67
68#include <sys/vmmeter.h>
69#include <sys/user.h>
e43a034f 70#include <sys/thread2.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
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86int forksleep; /* Place for fork1() to sleep on. */
87
88/* ARGSUSED */
89int
41c20dac 90fork(struct fork_args *uap)
984263bc 91{
553ea3c8 92 struct lwp *lp = curthread->td_lwp;
984263bc 93 struct proc *p2;
41c20dac 94 int error;
984263bc 95
553ea3c8 96 error = fork1(lp, RFFDG | RFPROC, &p2);
984263bc 97 if (error == 0) {
553ea3c8 98 start_forked_proc(lp, p2);
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99 uap->sysmsg_fds[0] = p2->p_pid;
100 uap->sysmsg_fds[1] = 0;
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101 }
102 return error;
103}
104
105/* ARGSUSED */
106int
41c20dac 107vfork(struct vfork_args *uap)
984263bc 108{
553ea3c8 109 struct lwp *lp = curthread->td_lwp;
984263bc 110 struct proc *p2;
41c20dac 111 int error;
984263bc 112
553ea3c8 113 error = fork1(lp, RFFDG | RFPROC | RFPPWAIT | RFMEM, &p2);
984263bc 114 if (error == 0) {
553ea3c8 115 start_forked_proc(lp, p2);
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116 uap->sysmsg_fds[0] = p2->p_pid;
117 uap->sysmsg_fds[1] = 0;
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118 }
119 return error;
120}
121
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122/*
123 * Handle rforks. An rfork may (1) operate on the current process without
124 * creating a new, (2) create a new process that shared the current process's
125 * vmspace, signals, and/or descriptors, or (3) create a new process that does
126 * not share these things (normal fork).
127 *
128 * Note that we only call start_forked_proc() if a new process is actually
129 * created.
130 *
131 * rfork { int flags }
132 */
984263bc 133int
41c20dac 134rfork(struct rfork_args *uap)
984263bc 135{
553ea3c8 136 struct lwp *lp = curthread->td_lwp;
984263bc 137 struct proc *p2;
41c20dac 138 int error;
984263bc 139
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140 if ((uap->flags & RFKERNELONLY) != 0)
141 return (EINVAL);
142
553ea3c8 143 error = fork1(lp, uap->flags, &p2);
984263bc 144 if (error == 0) {
f61c1ff1 145 if (p2)
553ea3c8 146 start_forked_proc(lp, p2);
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147 uap->sysmsg_fds[0] = p2 ? p2->p_pid : 0;
148 uap->sysmsg_fds[1] = 0;
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149 }
150 return error;
151}
152
153
154int nprocs = 1; /* process 0 */
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155
156int
553ea3c8 157fork1(struct lwp *lp1, int flags, struct proc **procp)
984263bc 158{
553ea3c8 159 struct proc *p1 = lp1->lwp_proc;
984263bc 160 struct proc *p2, *pptr;
553ea3c8 161 struct lwp *lp2;
984263bc 162 uid_t uid;
984263bc 163 int ok;
51e64ff2 164 static int curfail = 0;
5bc7cd8d 165 static struct timeval lastfail;
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166 struct forklist *ep;
167 struct filedesc_to_leader *fdtol;
168
169 if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG))
170 return (EINVAL);
171
172 /*
173 * Here we don't create a new process, but we divorce
174 * certain parts of a process from itself.
175 */
176 if ((flags & RFPROC) == 0) {
177
178 vm_fork(p1, 0, flags);
179
180 /*
181 * Close all file descriptors.
182 */
183 if (flags & RFCFDG) {
184 struct filedesc *fdtmp;
185 fdtmp = fdinit(p1);
186 fdfree(p1);
187 p1->p_fd = fdtmp;
188 }
189
190 /*
191 * Unshare file descriptors (from parent.)
192 */
193 if (flags & RFFDG) {
194 if (p1->p_fd->fd_refcnt > 1) {
195 struct filedesc *newfd;
196 newfd = fdcopy(p1);
197 fdfree(p1);
198 p1->p_fd = newfd;
199 }
200 }
201 *procp = NULL;
202 return (0);
203 }
204
205 /*
206 * Although process entries are dynamically created, we still keep
207 * a global limit on the maximum number we will create. Don't allow
208 * a nonprivileged user to use the last ten processes; don't let root
209 * exceed the limit. The variable nprocs is the current number of
210 * processes, maxproc is the limit.
211 */
41c20dac 212 uid = p1->p_ucred->cr_ruid;
984263bc 213 if ((nprocs >= maxproc - 10 && uid != 0) || nprocs >= maxproc) {
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214 if (ppsratecheck(&lastfail, &curfail, 1))
215 printf("maxproc limit exceeded by uid %d, please "
216 "see tuning(7) and login.conf(5).\n", uid);
377d4740 217 tsleep(&forksleep, 0, "fork", hz / 2);
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218 return (EAGAIN);
219 }
220 /*
221 * Increment the nprocs resource before blocking can occur. There
222 * are hard-limits as to the number of processes that can run.
223 */
224 nprocs++;
225
226 /*
227 * Increment the count of procs running with this uid. Don't allow
228 * a nonprivileged user to exceed their current limit.
229 */
41c20dac 230 ok = chgproccnt(p1->p_ucred->cr_ruidinfo, 1,
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231 (uid != 0) ? p1->p_rlimit[RLIMIT_NPROC].rlim_cur : 0);
232 if (!ok) {
233 /*
234 * Back out the process count
235 */
236 nprocs--;
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237 if (ppsratecheck(&lastfail, &curfail, 1))
238 printf("maxproc limit exceeded by uid %d, please "
239 "see tuning(7) and login.conf(5).\n", uid);
377d4740 240 tsleep(&forksleep, 0, "fork", hz / 2);
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241 return (EAGAIN);
242 }
243
244 /* Allocate new proc. */
51e64ff2 245 p2 = zalloc(proc_zone);
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246
247 /*
ef09c3ed 248 * Setup linkage for kernel based threading XXX lwp
984263bc 249 */
cb74210d 250 if (flags & RFTHREAD) {
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251 p2->p_peers = p1->p_peers;
252 p1->p_peers = p2;
253 p2->p_leader = p1->p_leader;
984263bc 254 } else {
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255 p2->p_peers = NULL;
256 p2->p_leader = p2;
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257 }
258
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259 p2->p_wakeup = 0;
260 p2->p_vmspace = NULL;
261 p2->p_numposixlocks = 0;
262 p2->p_emuldata = NULL;
263 TAILQ_INIT(&p2->p_lwp.lwp_sysmsgq);
264 LIST_INIT(&p2->p_lwps);
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265
266 /* XXX lwp */
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267 lp2 = &p2->p_lwp;
268 lp2->lwp_proc = p2;
553ea3c8 269 lp2->lwp_tid = 0;
a60ccb85 270 lp2->lwp_cpumask = 0xFFFFFFFF; /* XXX inherit ? */
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271 LIST_INSERT_HEAD(&p2->p_lwps, lp2, lwp_list);
272 p2->p_nthreads = 1;
273 p2->p_nstopped = 0;
274 p2->p_lasttid = 0;
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275
276 /*
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277 * Setting the state to SIDL protects the partially initialized
278 * process once it starts getting hooked into the rest of the system.
984263bc 279 */
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280 p2->p_stat = SIDL;
281 proc_add_allproc(p2);
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282
283 /*
284 * Make a proc table entry for the new process.
285 * Start by zeroing the section of proc that is zero-initialized,
286 * then copy the section that is copied directly from the parent.
287 */
288 bzero(&p2->p_startzero,
289 (unsigned) ((caddr_t)&p2->p_endzero - (caddr_t)&p2->p_startzero));
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290 bzero(&lp2->lwp_startzero,
291 (unsigned) ((caddr_t)&lp2->lwp_endzero -
292 (caddr_t)&lp2->lwp_startzero));
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293 bcopy(&p1->p_startcopy, &p2->p_startcopy,
294 (unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy));
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295 bcopy(&p1->p_lwp.lwp_startcopy, &lp2->lwp_startcopy,
296 (unsigned) ((caddr_t)&lp2->lwp_endcopy -
297 (caddr_t)&lp2->lwp_startcopy));
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298
299 p2->p_aioinfo = NULL;
300
301 /*
302 * Duplicate sub-structures as needed.
303 * Increase reference counts on shared objects.
304 * The p_stats and p_sigacts substructs are set in vm_fork.
3a72e617 305 * p_lock is in the copy area and must be cleared.
984263bc 306 */
344ad853 307 p2->p_flag = 0;
3a72e617 308 p2->p_lock = 0;
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309 if (p1->p_flag & P_PROFIL)
310 startprofclock(p2);
dadab5e9 311 p2->p_ucred = crhold(p1->p_ucred);
984263bc 312
b40e316c 313 if (jailed(p2->p_ucred))
984263bc 314 p2->p_flag |= P_JAILED;
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315
316 if (p2->p_args)
317 p2->p_args->ar_ref++;
318
319 if (flags & RFSIGSHARE) {
320 p2->p_procsig = p1->p_procsig;
321 p2->p_procsig->ps_refcnt++;
322 if (p1->p_sigacts == &p1->p_addr->u_sigacts) {
323 struct sigacts *newsigacts;
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324
325 /* Create the shared sigacts structure */
326 MALLOC(newsigacts, struct sigacts *,
327 sizeof(struct sigacts), M_SUBPROC, M_WAITOK);
e43a034f 328 crit_enter();
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329 /*
330 * Set p_sigacts to the new shared structure.
331 * Note that this is updating p1->p_sigacts at the
332 * same time, since p_sigacts is just a pointer to
333 * the shared p_procsig->ps_sigacts.
334 */
335 p2->p_sigacts = newsigacts;
336 bcopy(&p1->p_addr->u_sigacts, p2->p_sigacts,
337 sizeof(*p2->p_sigacts));
338 *p2->p_sigacts = p1->p_addr->u_sigacts;
e43a034f 339 crit_exit();
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340 }
341 } else {
342 MALLOC(p2->p_procsig, struct procsig *, sizeof(struct procsig),
343 M_SUBPROC, M_WAITOK);
344 bcopy(p1->p_procsig, p2->p_procsig, sizeof(*p2->p_procsig));
345 p2->p_procsig->ps_refcnt = 1;
346 p2->p_sigacts = NULL; /* finished in vm_fork() */
347 }
348 if (flags & RFLINUXTHPN)
349 p2->p_sigparent = SIGUSR1;
350 else
351 p2->p_sigparent = SIGCHLD;
352
353 /* bump references to the text vnode (for procfs) */
354 p2->p_textvp = p1->p_textvp;
355 if (p2->p_textvp)
597aea93 356 vref(p2->p_textvp);
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357
358 if (flags & RFCFDG) {
359 p2->p_fd = fdinit(p1);
360 fdtol = NULL;
361 } else if (flags & RFFDG) {
362 p2->p_fd = fdcopy(p1);
363 fdtol = NULL;
364 } else {
365 p2->p_fd = fdshare(p1);
366 if (p1->p_fdtol == NULL)
367 p1->p_fdtol =
368 filedesc_to_leader_alloc(NULL,
369 p1->p_leader);
370 if ((flags & RFTHREAD) != 0) {
371 /*
372 * Shared file descriptor table and
373 * shared process leaders.
374 */
375 fdtol = p1->p_fdtol;
376 fdtol->fdl_refcount++;
377 } else {
378 /*
379 * Shared file descriptor table, and
380 * different process leaders
381 */
98a7f915 382 fdtol = filedesc_to_leader_alloc(p1->p_fdtol, p2);
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383 }
384 }
385 p2->p_fdtol = fdtol;
c0b8a06d 386 p2->p_limit = plimit_fork(p1->p_limit);
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387
388 /*
389 * Preserve some more flags in subprocess. P_PROFIL has already
390 * been preserved.
391 */
392 p2->p_flag |= p1->p_flag & (P_SUGID | P_ALTSTACK);
393 if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT)
394 p2->p_flag |= P_CONTROLT;
395 if (flags & RFPPWAIT)
396 p2->p_flag |= P_PPWAIT;
397
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398 /*
399 * Once we are on a pglist we may receive signals. XXX we might
400 * race a ^C being sent to the process group by not receiving it
401 * at all prior to this line.
402 */
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403 LIST_INSERT_AFTER(p1, p2, p_pglist);
404
405 /*
406 * Attach the new process to its parent.
407 *
408 * If RFNOWAIT is set, the newly created process becomes a child
409 * of init. This effectively disassociates the child from the
410 * parent.
411 */
412 if (flags & RFNOWAIT)
413 pptr = initproc;
414 else
415 pptr = p1;
416 p2->p_pptr = pptr;
417 LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling);
418 LIST_INIT(&p2->p_children);
98a7f915 419 varsymset_init(&p2->p_varsymset, &p1->p_varsymset);
8fbf9130 420 callout_init(&p2->p_ithandle);
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421
422#ifdef KTRACE
423 /*
424 * Copy traceflag and tracefile if enabled. If not inherited,
425 * these were zeroed above but we still could have a trace race
29f58392 426 * so make sure p2's p_tracenode is NULL.
984263bc 427 */
29f58392 428 if ((p1->p_traceflag & KTRFAC_INHERIT) && p2->p_tracenode == NULL) {
984263bc 429 p2->p_traceflag = p1->p_traceflag;
29f58392 430 p2->p_tracenode = ktrinherit(p1->p_tracenode);
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431 }
432#endif
433
434 /*
352f5709 435 * Inherit the scheduler and initialize scheduler-related fields.
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436 * Set cpbase to the last timeout that occured (not the upcoming
437 * timeout).
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438 *
439 * A critical section is required since a timer IPI can update
440 * scheduler specific data.
a77ac49d 441 */
50017724 442 crit_enter();
a77ac49d 443 p2->p_usched = p1->p_usched;
553ea3c8 444 lp2->lwp_cpbase = mycpu->gd_schedclock.time -
dcc99b62 445 mycpu->gd_schedclock.periodic;
553ea3c8 446 p2->p_usched->heuristic_forking(&p1->p_lwp, lp2);
50017724 447 crit_exit();
a77ac49d 448
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449 /*
450 * This begins the section where we must prevent the parent
451 * from being swapped.
452 */
453 PHOLD(p1);
454
455 /*
456 * Finish creating the child process. It will return via a different
457 * execution path later. (ie: directly into user mode)
458 */
459 vm_fork(p1, p2, flags);
e30f9e2c 460 caps_fork(p1, p2, flags);
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461
462 if (flags == (RFFDG | RFPROC)) {
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463 mycpu->gd_cnt.v_forks++;
464 mycpu->gd_cnt.v_forkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize;
984263bc 465 } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM)) {
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466 mycpu->gd_cnt.v_vforks++;
467 mycpu->gd_cnt.v_vforkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize;
984263bc 468 } else if (p1 == &proc0) {
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469 mycpu->gd_cnt.v_kthreads++;
470 mycpu->gd_cnt.v_kthreadpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize;
984263bc 471 } else {
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472 mycpu->gd_cnt.v_rforks++;
473 mycpu->gd_cnt.v_rforkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize;
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474 }
475
476 /*
477 * Both processes are set up, now check if any loadable modules want
478 * to adjust anything.
479 * What if they have an error? XXX
480 */
481 TAILQ_FOREACH(ep, &fork_list, next) {
482 (*ep->function)(p1, p2, flags);
483 }
484
485 /*
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486 * Set the start time. Note that the process is not runnable. The
487 * caller is responsible for making it runnable.
984263bc 488 */
d9fa5f67 489 microtime(&p2->p_start);
984263bc 490 p2->p_acflag = AFORK;
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491
492 /*
493 * tell any interested parties about the new process
494 */
495 KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid);
496
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497 /*
498 * Return child proc pointer to parent.
499 */
500 *procp = p2;
501 return (0);
502}
503
504/*
505 * The next two functionms are general routines to handle adding/deleting
506 * items on the fork callout list.
507 *
508 * at_fork():
509 * Take the arguments given and put them onto the fork callout list,
510 * However first make sure that it's not already there.
511 * Returns 0 on success or a standard error number.
512 */
984263bc 513int
303c76d5 514at_fork(forklist_fn function)
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515{
516 struct forklist *ep;
517
518#ifdef INVARIANTS
519 /* let the programmer know if he's been stupid */
303c76d5 520 if (rm_at_fork(function)) {
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521 printf("WARNING: fork callout entry (%p) already present\n",
522 function);
303c76d5 523 }
984263bc 524#endif
679246c3 525 ep = malloc(sizeof(*ep), M_ATFORK, M_WAITOK|M_ZERO);
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526 ep->function = function;
527 TAILQ_INSERT_TAIL(&fork_list, ep, next);
528 return (0);
529}
530
531/*
532 * Scan the exit callout list for the given item and remove it..
533 * Returns the number of items removed (0 or 1)
534 */
984263bc 535int
303c76d5 536rm_at_fork(forklist_fn function)
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537{
538 struct forklist *ep;
539
540 TAILQ_FOREACH(ep, &fork_list, next) {
541 if (ep->function == function) {
542 TAILQ_REMOVE(&fork_list, ep, next);
543 free(ep, M_ATFORK);
544 return(1);
545 }
546 }
547 return (0);
548}
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549
550/*
551 * Add a forked process to the run queue after any remaining setup, such
552 * as setting the fork handler, has been completed.
553 */
7d0bac62 554void
553ea3c8 555start_forked_proc(struct lwp *lp1, struct proc *p2)
7d0bac62 556{
553ea3c8
SS
557 struct lwp *lp2;
558
559 KKASSERT(p2 != NULL && p2->p_nthreads == 1);
560
561 lp2 = LIST_FIRST(&p2->p_lwps);
562
7d0bac62 563 /*
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564 * Move from SIDL to RUN queue, and activate the process's thread.
565 * Activation of the thread effectively makes the process "a"
566 * current process, so we do not setrunqueue().
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567 *
568 * YYY setrunqueue works here but we should clean up the trampoline
569 * code so we just schedule the LWKT thread and let the trampoline
570 * deal with the userland scheduler on return to userland.
7d0bac62 571 */
553ea3c8 572 KASSERT(p2->p_stat == SIDL,
7d0bac62 573 ("cannot start forked process, bad status: %p", p2));
553ea3c8 574 p2->p_usched->resetpriority(lp2);
e43a034f 575 crit_enter();
7d0bac62 576 p2->p_stat = SRUN;
553ea3c8 577 p2->p_usched->setrunqueue(lp2);
e43a034f 578 crit_exit();
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579
580 /*
581 * Now can be swapped.
582 */
553ea3c8 583 PRELE(lp1->lwp_proc);
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584
585 /*
586 * Preserve synchronization semantics of vfork. If waiting for
587 * child to exec or exit, set P_PPWAIT on child, and sleep on our
588 * proc (in case of exit).
589 */
590 while (p2->p_flag & P_PPWAIT)
553ea3c8 591 tsleep(lp1->lwp_proc, 0, "ppwait", 0);
7d0bac62 592}