1 | /* $NetBSD: kern_fork.c,v 1.196 2016/11/04 18:14:04 christos Exp $ */ |
2 | |
3 | /*- |
4 | * Copyright (c) 1999, 2001, 2004, 2006, 2007, 2008 The NetBSD Foundation, Inc. |
5 | * All rights reserved. |
6 | * |
7 | * This code is derived from software contributed to The NetBSD Foundation |
8 | * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, |
9 | * NASA Ames Research Center, by Charles M. Hannum, and by Andrew Doran. |
10 | * |
11 | * Redistribution and use in source and binary forms, with or without |
12 | * modification, are permitted provided that the following conditions |
13 | * are met: |
14 | * 1. Redistributions of source code must retain the above copyright |
15 | * notice, this list of conditions and the following disclaimer. |
16 | * 2. Redistributions in binary form must reproduce the above copyright |
17 | * notice, this list of conditions and the following disclaimer in the |
18 | * documentation and/or other materials provided with the distribution. |
19 | * |
20 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
21 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
22 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
23 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
24 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
25 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
26 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
27 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
28 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
29 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
30 | * POSSIBILITY OF SUCH DAMAGE. |
31 | */ |
32 | |
33 | /* |
34 | * Copyright (c) 1982, 1986, 1989, 1991, 1993 |
35 | * The Regents of the University of California. All rights reserved. |
36 | * (c) UNIX System Laboratories, Inc. |
37 | * All or some portions of this file are derived from material licensed |
38 | * to the University of California by American Telephone and Telegraph |
39 | * Co. or Unix System Laboratories, Inc. and are reproduced herein with |
40 | * the permission of UNIX System Laboratories, Inc. |
41 | * |
42 | * Redistribution and use in source and binary forms, with or without |
43 | * modification, are permitted provided that the following conditions |
44 | * are met: |
45 | * 1. Redistributions of source code must retain the above copyright |
46 | * notice, this list of conditions and the following disclaimer. |
47 | * 2. Redistributions in binary form must reproduce the above copyright |
48 | * notice, this list of conditions and the following disclaimer in the |
49 | * documentation and/or other materials provided with the distribution. |
50 | * 3. Neither the name of the University nor the names of its contributors |
51 | * may be used to endorse or promote products derived from this software |
52 | * without specific prior written permission. |
53 | * |
54 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
55 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
56 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
57 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
58 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
59 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
60 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
61 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
62 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
63 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
64 | * SUCH DAMAGE. |
65 | * |
66 | * @(#)kern_fork.c 8.8 (Berkeley) 2/14/95 |
67 | */ |
68 | |
69 | #include <sys/cdefs.h> |
70 | __KERNEL_RCSID(0, "$NetBSD: kern_fork.c,v 1.196 2016/11/04 18:14:04 christos Exp $" ); |
71 | |
72 | #include "opt_ktrace.h" |
73 | #include "opt_dtrace.h" |
74 | |
75 | #include <sys/param.h> |
76 | #include <sys/systm.h> |
77 | #include <sys/filedesc.h> |
78 | #include <sys/kernel.h> |
79 | #include <sys/pool.h> |
80 | #include <sys/mount.h> |
81 | #include <sys/proc.h> |
82 | #include <sys/ras.h> |
83 | #include <sys/resourcevar.h> |
84 | #include <sys/vnode.h> |
85 | #include <sys/file.h> |
86 | #include <sys/acct.h> |
87 | #include <sys/ktrace.h> |
88 | #include <sys/sched.h> |
89 | #include <sys/signalvar.h> |
90 | #include <sys/kauth.h> |
91 | #include <sys/atomic.h> |
92 | #include <sys/syscallargs.h> |
93 | #include <sys/uidinfo.h> |
94 | #include <sys/sdt.h> |
95 | #include <sys/ptrace.h> |
96 | |
97 | #include <uvm/uvm_extern.h> |
98 | |
99 | /* |
100 | * DTrace SDT provider definitions |
101 | */ |
102 | SDT_PROVIDER_DECLARE(proc); |
103 | SDT_PROBE_DEFINE3(proc, kernel, , create, |
104 | "struct proc *" , /* new process */ |
105 | "struct proc *" , /* parent process */ |
106 | "int" /* flags */); |
107 | |
108 | u_int nprocs __cacheline_aligned = 1; /* process 0 */ |
109 | |
110 | /* |
111 | * Number of ticks to sleep if fork() would fail due to process hitting |
112 | * limits. Exported in miliseconds to userland via sysctl. |
113 | */ |
114 | int forkfsleep = 0; |
115 | |
116 | int |
117 | sys_fork(struct lwp *l, const void *v, register_t *retval) |
118 | { |
119 | |
120 | return fork1(l, 0, SIGCHLD, NULL, 0, NULL, NULL, retval, NULL); |
121 | } |
122 | |
123 | /* |
124 | * vfork(2) system call compatible with 4.4BSD (i.e. BSD with Mach VM). |
125 | * Address space is not shared, but parent is blocked until child exit. |
126 | */ |
127 | int |
128 | sys_vfork(struct lwp *l, const void *v, register_t *retval) |
129 | { |
130 | |
131 | return fork1(l, FORK_PPWAIT, SIGCHLD, NULL, 0, NULL, NULL, |
132 | retval, NULL); |
133 | } |
134 | |
135 | /* |
136 | * New vfork(2) system call for NetBSD, which implements original 3BSD vfork(2) |
137 | * semantics. Address space is shared, and parent is blocked until child exit. |
138 | */ |
139 | int |
140 | sys___vfork14(struct lwp *l, const void *v, register_t *retval) |
141 | { |
142 | |
143 | return fork1(l, FORK_PPWAIT|FORK_SHAREVM, SIGCHLD, NULL, 0, |
144 | NULL, NULL, retval, NULL); |
145 | } |
146 | |
147 | /* |
148 | * Linux-compatible __clone(2) system call. |
149 | */ |
150 | int |
151 | sys___clone(struct lwp *l, const struct sys___clone_args *uap, |
152 | register_t *retval) |
153 | { |
154 | /* { |
155 | syscallarg(int) flags; |
156 | syscallarg(void *) stack; |
157 | } */ |
158 | int flags, sig; |
159 | |
160 | /* |
161 | * We don't support the CLONE_PID or CLONE_PTRACE flags. |
162 | */ |
163 | if (SCARG(uap, flags) & (CLONE_PID|CLONE_PTRACE)) |
164 | return EINVAL; |
165 | |
166 | /* |
167 | * Linux enforces CLONE_VM with CLONE_SIGHAND, do same. |
168 | */ |
169 | if (SCARG(uap, flags) & CLONE_SIGHAND |
170 | && (SCARG(uap, flags) & CLONE_VM) == 0) |
171 | return EINVAL; |
172 | |
173 | flags = 0; |
174 | |
175 | if (SCARG(uap, flags) & CLONE_VM) |
176 | flags |= FORK_SHAREVM; |
177 | if (SCARG(uap, flags) & CLONE_FS) |
178 | flags |= FORK_SHARECWD; |
179 | if (SCARG(uap, flags) & CLONE_FILES) |
180 | flags |= FORK_SHAREFILES; |
181 | if (SCARG(uap, flags) & CLONE_SIGHAND) |
182 | flags |= FORK_SHARESIGS; |
183 | if (SCARG(uap, flags) & CLONE_VFORK) |
184 | flags |= FORK_PPWAIT; |
185 | |
186 | sig = SCARG(uap, flags) & CLONE_CSIGNAL; |
187 | if (sig < 0 || sig >= _NSIG) |
188 | return EINVAL; |
189 | |
190 | /* |
191 | * Note that the Linux API does not provide a portable way of |
192 | * specifying the stack area; the caller must know if the stack |
193 | * grows up or down. So, we pass a stack size of 0, so that the |
194 | * code that makes this adjustment is a noop. |
195 | */ |
196 | return fork1(l, flags, sig, SCARG(uap, stack), 0, |
197 | NULL, NULL, retval, NULL); |
198 | } |
199 | |
200 | /* |
201 | * Print the 'table full' message once per 10 seconds. |
202 | */ |
203 | static struct timeval fork_tfmrate = { 10, 0 }; |
204 | |
205 | /* |
206 | * General fork call. Note that another LWP in the process may call exec() |
207 | * or exit() while we are forking. It's safe to continue here, because |
208 | * neither operation will complete until all LWPs have exited the process. |
209 | */ |
210 | int |
211 | fork1(struct lwp *l1, int flags, int exitsig, void *stack, size_t stacksize, |
212 | void (*func)(void *), void *arg, register_t *retval, |
213 | struct proc **rnewprocp) |
214 | { |
215 | struct proc *p1, *p2, *parent; |
216 | struct plimit *p1_lim; |
217 | uid_t uid; |
218 | struct lwp *l2; |
219 | int count; |
220 | vaddr_t uaddr; |
221 | int tnprocs; |
222 | int tracefork; |
223 | int error = 0; |
224 | |
225 | p1 = l1->l_proc; |
226 | uid = kauth_cred_getuid(l1->l_cred); |
227 | tnprocs = atomic_inc_uint_nv(&nprocs); |
228 | |
229 | /* |
230 | * Although process entries are dynamically created, we still keep |
231 | * a global limit on the maximum number we will create. |
232 | */ |
233 | if (__predict_false(tnprocs >= maxproc)) |
234 | error = -1; |
235 | else |
236 | error = kauth_authorize_process(l1->l_cred, |
237 | KAUTH_PROCESS_FORK, p1, KAUTH_ARG(tnprocs), NULL, NULL); |
238 | |
239 | if (error) { |
240 | static struct timeval lasttfm; |
241 | atomic_dec_uint(&nprocs); |
242 | if (ratecheck(&lasttfm, &fork_tfmrate)) |
243 | tablefull("proc" , "increase kern.maxproc or NPROC" ); |
244 | if (forkfsleep) |
245 | kpause("forkmx" , false, forkfsleep, NULL); |
246 | return EAGAIN; |
247 | } |
248 | |
249 | /* |
250 | * Enforce limits. |
251 | */ |
252 | count = chgproccnt(uid, 1); |
253 | if (__predict_false(count > p1->p_rlimit[RLIMIT_NPROC].rlim_cur)) { |
254 | if (kauth_authorize_process(l1->l_cred, KAUTH_PROCESS_RLIMIT, |
255 | p1, KAUTH_ARG(KAUTH_REQ_PROCESS_RLIMIT_BYPASS), |
256 | &p1->p_rlimit[RLIMIT_NPROC], KAUTH_ARG(RLIMIT_NPROC)) != 0) { |
257 | (void)chgproccnt(uid, -1); |
258 | atomic_dec_uint(&nprocs); |
259 | if (forkfsleep) |
260 | kpause("forkulim" , false, forkfsleep, NULL); |
261 | return EAGAIN; |
262 | } |
263 | } |
264 | |
265 | /* |
266 | * Allocate virtual address space for the U-area now, while it |
267 | * is still easy to abort the fork operation if we're out of |
268 | * kernel virtual address space. |
269 | */ |
270 | uaddr = uvm_uarea_alloc(); |
271 | if (__predict_false(uaddr == 0)) { |
272 | (void)chgproccnt(uid, -1); |
273 | atomic_dec_uint(&nprocs); |
274 | return ENOMEM; |
275 | } |
276 | |
277 | /* |
278 | * We are now committed to the fork. From here on, we may |
279 | * block on resources, but resource allocation may NOT fail. |
280 | */ |
281 | |
282 | /* Allocate new proc. */ |
283 | p2 = proc_alloc(); |
284 | |
285 | /* |
286 | * Make a proc table entry for the new process. |
287 | * Start by zeroing the section of proc that is zero-initialized, |
288 | * then copy the section that is copied directly from the parent. |
289 | */ |
290 | memset(&p2->p_startzero, 0, |
291 | (unsigned) ((char *)&p2->p_endzero - (char *)&p2->p_startzero)); |
292 | memcpy(&p2->p_startcopy, &p1->p_startcopy, |
293 | (unsigned) ((char *)&p2->p_endcopy - (char *)&p2->p_startcopy)); |
294 | |
295 | TAILQ_INIT(&p2->p_sigpend.sp_info); |
296 | |
297 | LIST_INIT(&p2->p_lwps); |
298 | LIST_INIT(&p2->p_sigwaiters); |
299 | |
300 | /* |
301 | * Duplicate sub-structures as needed. |
302 | * Increase reference counts on shared objects. |
303 | * Inherit flags we want to keep. The flags related to SIGCHLD |
304 | * handling are important in order to keep a consistent behaviour |
305 | * for the child after the fork. If we are a 32-bit process, the |
306 | * child will be too. |
307 | */ |
308 | p2->p_flag = |
309 | p1->p_flag & (PK_SUGID | PK_NOCLDWAIT | PK_CLDSIGIGN | PK_32); |
310 | p2->p_emul = p1->p_emul; |
311 | p2->p_execsw = p1->p_execsw; |
312 | |
313 | if (flags & FORK_SYSTEM) { |
314 | /* |
315 | * Mark it as a system process. Set P_NOCLDWAIT so that |
316 | * children are reparented to init(8) when they exit. |
317 | * init(8) can easily wait them out for us. |
318 | */ |
319 | p2->p_flag |= (PK_SYSTEM | PK_NOCLDWAIT); |
320 | } |
321 | |
322 | mutex_init(&p2->p_stmutex, MUTEX_DEFAULT, IPL_HIGH); |
323 | mutex_init(&p2->p_auxlock, MUTEX_DEFAULT, IPL_NONE); |
324 | rw_init(&p2->p_reflock); |
325 | cv_init(&p2->p_waitcv, "wait" ); |
326 | cv_init(&p2->p_lwpcv, "lwpwait" ); |
327 | |
328 | /* |
329 | * Share a lock between the processes if they are to share signal |
330 | * state: we must synchronize access to it. |
331 | */ |
332 | if (flags & FORK_SHARESIGS) { |
333 | p2->p_lock = p1->p_lock; |
334 | mutex_obj_hold(p1->p_lock); |
335 | } else |
336 | p2->p_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE); |
337 | |
338 | kauth_proc_fork(p1, p2); |
339 | |
340 | p2->p_raslist = NULL; |
341 | #if defined(__HAVE_RAS) |
342 | ras_fork(p1, p2); |
343 | #endif |
344 | |
345 | /* bump references to the text vnode (for procfs) */ |
346 | p2->p_textvp = p1->p_textvp; |
347 | if (p2->p_textvp) |
348 | vref(p2->p_textvp); |
349 | |
350 | if (flags & FORK_SHAREFILES) |
351 | fd_share(p2); |
352 | else if (flags & FORK_CLEANFILES) |
353 | p2->p_fd = fd_init(NULL); |
354 | else |
355 | p2->p_fd = fd_copy(); |
356 | |
357 | /* XXX racy */ |
358 | p2->p_mqueue_cnt = p1->p_mqueue_cnt; |
359 | |
360 | if (flags & FORK_SHARECWD) |
361 | cwdshare(p2); |
362 | else |
363 | p2->p_cwdi = cwdinit(); |
364 | |
365 | /* |
366 | * Note: p_limit (rlimit stuff) is copy-on-write, so normally |
367 | * we just need increase pl_refcnt. |
368 | */ |
369 | p1_lim = p1->p_limit; |
370 | if (!p1_lim->pl_writeable) { |
371 | lim_addref(p1_lim); |
372 | p2->p_limit = p1_lim; |
373 | } else { |
374 | p2->p_limit = lim_copy(p1_lim); |
375 | } |
376 | |
377 | if (flags & FORK_PPWAIT) { |
378 | /* Mark ourselves as waiting for a child. */ |
379 | l1->l_pflag |= LP_VFORKWAIT; |
380 | p2->p_lflag = PL_PPWAIT; |
381 | p2->p_vforklwp = l1; |
382 | } else { |
383 | p2->p_lflag = 0; |
384 | } |
385 | p2->p_sflag = 0; |
386 | p2->p_slflag = 0; |
387 | parent = (flags & FORK_NOWAIT) ? initproc : p1; |
388 | p2->p_pptr = parent; |
389 | p2->p_ppid = parent->p_pid; |
390 | LIST_INIT(&p2->p_children); |
391 | |
392 | p2->p_aio = NULL; |
393 | |
394 | #ifdef KTRACE |
395 | /* |
396 | * Copy traceflag and tracefile if enabled. |
397 | * If not inherited, these were zeroed above. |
398 | */ |
399 | if (p1->p_traceflag & KTRFAC_INHERIT) { |
400 | mutex_enter(&ktrace_lock); |
401 | p2->p_traceflag = p1->p_traceflag; |
402 | if ((p2->p_tracep = p1->p_tracep) != NULL) |
403 | ktradref(p2); |
404 | mutex_exit(&ktrace_lock); |
405 | } |
406 | #endif |
407 | |
408 | /* |
409 | * Create signal actions for the child process. |
410 | */ |
411 | p2->p_sigacts = sigactsinit(p1, flags & FORK_SHARESIGS); |
412 | mutex_enter(p1->p_lock); |
413 | p2->p_sflag |= |
414 | (p1->p_sflag & (PS_STOPFORK | PS_STOPEXEC | PS_NOCLDSTOP)); |
415 | sched_proc_fork(p1, p2); |
416 | mutex_exit(p1->p_lock); |
417 | |
418 | p2->p_stflag = p1->p_stflag; |
419 | |
420 | /* |
421 | * p_stats. |
422 | * Copy parts of p_stats, and zero out the rest. |
423 | */ |
424 | p2->p_stats = pstatscopy(p1->p_stats); |
425 | |
426 | /* |
427 | * Set up the new process address space. |
428 | */ |
429 | uvm_proc_fork(p1, p2, (flags & FORK_SHAREVM) ? true : false); |
430 | |
431 | /* |
432 | * Finish creating the child process. |
433 | * It will return through a different path later. |
434 | */ |
435 | lwp_create(l1, p2, uaddr, (flags & FORK_PPWAIT) ? LWP_VFORK : 0, |
436 | stack, stacksize, (func != NULL) ? func : child_return, arg, &l2, |
437 | l1->l_class); |
438 | |
439 | /* |
440 | * Inherit l_private from the parent. |
441 | * Note that we cannot use lwp_setprivate() here since that |
442 | * also sets the CPU TLS register, which is incorrect if the |
443 | * process has changed that without letting the kernel know. |
444 | */ |
445 | l2->l_private = l1->l_private; |
446 | |
447 | /* |
448 | * If emulation has a process fork hook, call it now. |
449 | */ |
450 | if (p2->p_emul->e_proc_fork) |
451 | (*p2->p_emul->e_proc_fork)(p2, l1, flags); |
452 | |
453 | /* |
454 | * ...and finally, any other random fork hooks that subsystems |
455 | * might have registered. |
456 | */ |
457 | doforkhooks(p2, p1); |
458 | |
459 | SDT_PROBE(proc, kernel, , create, p2, p1, flags, 0, 0); |
460 | |
461 | /* |
462 | * It's now safe for the scheduler and other processes to see the |
463 | * child process. |
464 | */ |
465 | mutex_enter(proc_lock); |
466 | |
467 | if (p1->p_session->s_ttyvp != NULL && p1->p_lflag & PL_CONTROLT) |
468 | p2->p_lflag |= PL_CONTROLT; |
469 | |
470 | LIST_INSERT_HEAD(&parent->p_children, p2, p_sibling); |
471 | p2->p_exitsig = exitsig; /* signal for parent on exit */ |
472 | |
473 | /* |
474 | * We don't want to tracefork vfork()ed processes because they |
475 | * will not receive the SIGTRAP until it is too late. |
476 | */ |
477 | tracefork = (p1->p_slflag & (PSL_TRACEFORK|PSL_TRACED)) == |
478 | (PSL_TRACEFORK|PSL_TRACED) && (flags && FORK_PPWAIT) == 0; |
479 | if (tracefork) { |
480 | proc_changeparent(p2, p1->p_pptr); |
481 | /* |
482 | * Set ptrace status. |
483 | */ |
484 | p1->p_fpid = p2->p_pid; |
485 | p2->p_fpid = p1->p_pid; |
486 | } |
487 | |
488 | LIST_INSERT_AFTER(p1, p2, p_pglist); |
489 | LIST_INSERT_HEAD(&allproc, p2, p_list); |
490 | |
491 | p2->p_trace_enabled = trace_is_enabled(p2); |
492 | #ifdef __HAVE_SYSCALL_INTERN |
493 | (*p2->p_emul->e_syscall_intern)(p2); |
494 | #endif |
495 | |
496 | /* |
497 | * Update stats now that we know the fork was successful. |
498 | */ |
499 | uvmexp.forks++; |
500 | if (flags & FORK_PPWAIT) |
501 | uvmexp.forks_ppwait++; |
502 | if (flags & FORK_SHAREVM) |
503 | uvmexp.forks_sharevm++; |
504 | |
505 | /* |
506 | * Pass a pointer to the new process to the caller. |
507 | */ |
508 | if (rnewprocp != NULL) |
509 | *rnewprocp = p2; |
510 | |
511 | if (ktrpoint(KTR_EMUL)) |
512 | p2->p_traceflag |= KTRFAC_TRC_EMUL; |
513 | |
514 | /* |
515 | * Notify any interested parties about the new process. |
516 | */ |
517 | if (!SLIST_EMPTY(&p1->p_klist)) { |
518 | mutex_exit(proc_lock); |
519 | KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid); |
520 | mutex_enter(proc_lock); |
521 | } |
522 | |
523 | /* |
524 | * Make child runnable, set start time, and add to run queue except |
525 | * if the parent requested the child to start in SSTOP state. |
526 | */ |
527 | mutex_enter(p2->p_lock); |
528 | |
529 | /* |
530 | * Start profiling. |
531 | */ |
532 | if ((p2->p_stflag & PST_PROFIL) != 0) { |
533 | mutex_spin_enter(&p2->p_stmutex); |
534 | startprofclock(p2); |
535 | mutex_spin_exit(&p2->p_stmutex); |
536 | } |
537 | |
538 | getmicrotime(&p2->p_stats->p_start); |
539 | p2->p_acflag = AFORK; |
540 | lwp_lock(l2); |
541 | KASSERT(p2->p_nrlwps == 1); |
542 | if (p2->p_sflag & PS_STOPFORK) { |
543 | struct schedstate_percpu *spc = &l2->l_cpu->ci_schedstate; |
544 | p2->p_nrlwps = 0; |
545 | p2->p_stat = SSTOP; |
546 | p2->p_waited = 0; |
547 | p1->p_nstopchild++; |
548 | l2->l_stat = LSSTOP; |
549 | KASSERT(l2->l_wchan == NULL); |
550 | lwp_unlock_to(l2, spc->spc_lwplock); |
551 | } else { |
552 | p2->p_nrlwps = 1; |
553 | p2->p_stat = SACTIVE; |
554 | l2->l_stat = LSRUN; |
555 | sched_enqueue(l2, false); |
556 | lwp_unlock(l2); |
557 | } |
558 | |
559 | /* |
560 | * Return child pid to parent process, |
561 | * marking us as parent via retval[1]. |
562 | */ |
563 | if (retval != NULL) { |
564 | retval[0] = p2->p_pid; |
565 | retval[1] = 0; |
566 | } |
567 | mutex_exit(p2->p_lock); |
568 | |
569 | /* |
570 | * Preserve synchronization semantics of vfork. If waiting for |
571 | * child to exec or exit, sleep until it clears LP_VFORKWAIT. |
572 | */ |
573 | #if 0 |
574 | while (l1->l_pflag & LP_VFORKWAIT) { |
575 | cv_wait(&l1->l_waitcv, proc_lock); |
576 | } |
577 | #else |
578 | while (p2->p_lflag & PL_PPWAIT) |
579 | cv_wait(&p1->p_waitcv, proc_lock); |
580 | #endif |
581 | |
582 | /* |
583 | * Let the parent know that we are tracing its child. |
584 | */ |
585 | if (tracefork) { |
586 | ksiginfo_t ksi; |
587 | |
588 | KSI_INIT_EMPTY(&ksi); |
589 | ksi.ksi_signo = SIGTRAP; |
590 | ksi.ksi_lid = l1->l_lid; |
591 | kpsignal(p1, &ksi, NULL); |
592 | } |
593 | mutex_exit(proc_lock); |
594 | |
595 | return 0; |
596 | } |
597 | |