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 39 * $FreeBSD$ 40 */ 41 42 #include "opt_ktrace.h" 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/sysproto.h> 47 #include <sys/filedesc.h> 48 #include <sys/kernel.h> 49 #include <sys/sysctl.h> 50 #include <sys/malloc.h> 51 #include <sys/mutex.h> 52 #include <sys/proc.h> 53 #include <sys/resourcevar.h> 54 #include <sys/syscall.h> 55 #include <sys/vnode.h> 56 #include <sys/acct.h> 57 #include <sys/ktr.h> 58 #include <sys/ktrace.h> 59 #include <sys/kthread.h> 60 #include <sys/unistd.h> 61 #include <sys/jail.h> 62 63 #include <vm/vm.h> 64 #include <sys/lock.h> 65 #include <vm/pmap.h> 66 #include <vm/vm_map.h> 67 #include <vm/vm_extern.h> 68 #include <vm/vm_zone.h> 69 70 #include <sys/vmmeter.h> 71 #include <sys/user.h> 72 73 static MALLOC_DEFINE(M_ATFORK, "atfork", "atfork callback"); 74 75 static int fast_vfork = 1; 76 SYSCTL_INT(_kern, OID_AUTO, fast_vfork, CTLFLAG_RW, &fast_vfork, 0, 77 "flag to indicate whether we have a fast vfork()"); 78 79 /* 80 * These are the stuctures used to create a callout list for things to do 81 * when forking a process 82 */ 83 struct forklist { 84 forklist_fn function; 85 TAILQ_ENTRY(forklist) next; 86 }; 87 88 TAILQ_HEAD(forklist_head, forklist); 89 static struct forklist_head fork_list = TAILQ_HEAD_INITIALIZER(fork_list); 90 91 #ifndef _SYS_SYSPROTO_H_ 92 struct fork_args { 93 int dummy; 94 }; 95 #endif 96 97 /* ARGSUSED */ 98 int 99 fork(p, uap) 100 struct proc *p; 101 struct fork_args *uap; 102 { 103 int error; 104 struct proc *p2; 105 106 error = fork1(p, RFFDG | RFPROC, &p2); 107 if (error == 0) { 108 p->p_retval[0] = p2->p_pid; 109 p->p_retval[1] = 0; 110 } 111 return error; 112 } 113 114 /* ARGSUSED */ 115 int 116 vfork(p, uap) 117 struct proc *p; 118 struct vfork_args *uap; 119 { 120 int error; 121 struct proc *p2; 122 123 error = fork1(p, RFFDG | RFPROC | RFPPWAIT | RFMEM, &p2); 124 if (error == 0) { 125 p->p_retval[0] = p2->p_pid; 126 p->p_retval[1] = 0; 127 } 128 return error; 129 } 130 131 int 132 rfork(p, uap) 133 struct proc *p; 134 struct rfork_args *uap; 135 { 136 int error; 137 struct proc *p2; 138 139 /* mask kernel only flags out of the user flags */ 140 error = fork1(p, uap->flags & ~RFKERNELONLY, &p2); 141 if (error == 0) { 142 p->p_retval[0] = p2 ? p2->p_pid : 0; 143 p->p_retval[1] = 0; 144 } 145 return error; 146 } 147 148 149 int nprocs = 1; /* process 0 */ 150 static int nextpid = 0; 151 152 /* 153 * Random component to nextpid generation. We mix in a random factor to make 154 * it a little harder to predict. We sanity check the modulus value to avoid 155 * doing it in critical paths. Don't let it be too small or we pointlessly 156 * waste randomness entropy, and don't let it be impossibly large. Using a 157 * modulus that is too big causes a LOT more process table scans and slows 158 * down fork processing as the pidchecked caching is defeated. 159 */ 160 static int randompid = 0; 161 162 static int 163 sysctl_kern_randompid(SYSCTL_HANDLER_ARGS) 164 { 165 int error, pid; 166 167 pid = randompid; 168 error = sysctl_handle_int(oidp, &pid, 0, req); 169 if (error || !req->newptr) 170 return (error); 171 if (pid < 0 || pid > PID_MAX - 100) /* out of range */ 172 pid = PID_MAX - 100; 173 else if (pid < 2) /* NOP */ 174 pid = 0; 175 else if (pid < 100) /* Make it reasonable */ 176 pid = 100; 177 randompid = pid; 178 return (error); 179 } 180 181 SYSCTL_PROC(_kern, OID_AUTO, randompid, CTLTYPE_INT|CTLFLAG_RW, 182 0, 0, sysctl_kern_randompid, "I", "Random PID modulus"); 183 184 int 185 fork1(p1, flags, procp) 186 struct proc *p1; /* parent proc */ 187 int flags; 188 struct proc **procp; /* child proc */ 189 { 190 struct proc *p2, *pptr; 191 uid_t uid; 192 struct proc *newproc; 193 int trypid; 194 int ok; 195 static int pidchecked = 0; 196 struct forklist *ep; 197 198 /* Can't copy and clear */ 199 if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG)) 200 return (EINVAL); 201 202 /* 203 * Here we don't create a new process, but we divorce 204 * certain parts of a process from itself. 205 */ 206 if ((flags & RFPROC) == 0) { 207 208 vm_fork(p1, 0, flags); 209 210 /* 211 * Close all file descriptors. 212 */ 213 if (flags & RFCFDG) { 214 struct filedesc *fdtmp; 215 fdtmp = fdinit(p1); 216 fdfree(p1); 217 p1->p_fd = fdtmp; 218 } 219 220 /* 221 * Unshare file descriptors (from parent.) 222 */ 223 if (flags & RFFDG) { 224 if (p1->p_fd->fd_refcnt > 1) { 225 struct filedesc *newfd; 226 newfd = fdcopy(p1); 227 fdfree(p1); 228 p1->p_fd = newfd; 229 } 230 } 231 *procp = NULL; 232 return (0); 233 } 234 235 /* 236 * Although process entries are dynamically created, we still keep 237 * a global limit on the maximum number we will create. Don't allow 238 * a nonprivileged user to use the last process; don't let root 239 * exceed the limit. The variable nprocs is the current number of 240 * processes, maxproc is the limit. 241 */ 242 uid = p1->p_cred->p_ruid; 243 if ((nprocs >= maxproc - 1 && uid != 0) || nprocs >= maxproc) { 244 tablefull("proc"); 245 return (EAGAIN); 246 } 247 /* 248 * Increment the nprocs resource before blocking can occur. There 249 * are hard-limits as to the number of processes that can run. 250 */ 251 nprocs++; 252 253 /* 254 * Increment the count of procs running with this uid. Don't allow 255 * a nonprivileged user to exceed their current limit. 256 */ 257 ok = chgproccnt(p1->p_cred->p_uidinfo, 1, 258 (uid != 0) ? p1->p_rlimit[RLIMIT_NPROC].rlim_cur : 0); 259 if (!ok) { 260 /* 261 * Back out the process count 262 */ 263 nprocs--; 264 return (EAGAIN); 265 } 266 267 /* Allocate new proc. */ 268 newproc = zalloc(proc_zone); 269 270 /* 271 * Setup linkage for kernel based threading 272 */ 273 if((flags & RFTHREAD) != 0) { 274 newproc->p_peers = p1->p_peers; 275 p1->p_peers = newproc; 276 newproc->p_leader = p1->p_leader; 277 } else { 278 newproc->p_peers = NULL; 279 newproc->p_leader = newproc; 280 } 281 282 newproc->p_vmspace = NULL; 283 284 /* 285 * Find an unused process ID. We remember a range of unused IDs 286 * ready to use (from nextpid+1 through pidchecked-1). 287 * 288 * If RFHIGHPID is set (used during system boot), do not allocate 289 * low-numbered pids. 290 */ 291 ALLPROC_LOCK(AP_EXCLUSIVE); 292 trypid = nextpid + 1; 293 if (flags & RFHIGHPID) { 294 if (trypid < 10) { 295 trypid = 10; 296 } 297 } else { 298 if (randompid) 299 trypid += arc4random() % randompid; 300 } 301 retry: 302 /* 303 * If the process ID prototype has wrapped around, 304 * restart somewhat above 0, as the low-numbered procs 305 * tend to include daemons that don't exit. 306 */ 307 if (trypid >= PID_MAX) { 308 trypid = trypid % PID_MAX; 309 if (trypid < 100) 310 trypid += 100; 311 pidchecked = 0; 312 } 313 if (trypid >= pidchecked) { 314 int doingzomb = 0; 315 316 pidchecked = PID_MAX; 317 /* 318 * Scan the active and zombie procs to check whether this pid 319 * is in use. Remember the lowest pid that's greater 320 * than trypid, so we can avoid checking for a while. 321 */ 322 p2 = LIST_FIRST(&allproc); 323 again: 324 for (; p2 != NULL; p2 = LIST_NEXT(p2, p_list)) { 325 while (p2->p_pid == trypid || 326 p2->p_pgrp->pg_id == trypid || 327 p2->p_session->s_sid == trypid) { 328 trypid++; 329 if (trypid >= pidchecked) 330 goto retry; 331 } 332 if (p2->p_pid > trypid && pidchecked > p2->p_pid) 333 pidchecked = p2->p_pid; 334 if (p2->p_pgrp->pg_id > trypid && 335 pidchecked > p2->p_pgrp->pg_id) 336 pidchecked = p2->p_pgrp->pg_id; 337 if (p2->p_session->s_sid > trypid && 338 pidchecked > p2->p_session->s_sid) 339 pidchecked = p2->p_session->s_sid; 340 } 341 if (!doingzomb) { 342 doingzomb = 1; 343 p2 = LIST_FIRST(&zombproc); 344 goto again; 345 } 346 } 347 348 /* 349 * RFHIGHPID does not mess with the nextpid counter during boot. 350 */ 351 if (flags & RFHIGHPID) 352 pidchecked = 0; 353 else 354 nextpid = trypid; 355 356 p2 = newproc; 357 p2->p_intr_nesting_level = 0; 358 p2->p_stat = SIDL; /* protect against others */ 359 p2->p_pid = trypid; 360 LIST_INSERT_HEAD(&allproc, p2, p_list); 361 LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash); 362 ALLPROC_LOCK(AP_RELEASE); 363 364 /* 365 * Make a proc table entry for the new process. 366 * Start by zeroing the section of proc that is zero-initialized, 367 * then copy the section that is copied directly from the parent. 368 */ 369 bzero(&p2->p_startzero, 370 (unsigned) ((caddr_t)&p2->p_endzero - (caddr_t)&p2->p_startzero)); 371 bcopy(&p1->p_startcopy, &p2->p_startcopy, 372 (unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy)); 373 374 mtx_init(&p2->p_mtx, "process lock", MTX_DEF); 375 p2->p_aioinfo = NULL; 376 377 /* 378 * Duplicate sub-structures as needed. 379 * Increase reference counts on shared objects. 380 * The p_stats and p_sigacts substructs are set in vm_fork. 381 */ 382 p2->p_flag = 0; 383 mtx_enter(&sched_lock, MTX_SPIN); 384 p2->p_sflag = PS_INMEM; 385 if (p1->p_sflag & PS_PROFIL) 386 startprofclock(p2); 387 mtx_exit(&sched_lock, MTX_SPIN); 388 MALLOC(p2->p_cred, struct pcred *, sizeof(struct pcred), 389 M_SUBPROC, M_WAITOK); 390 bcopy(p1->p_cred, p2->p_cred, sizeof(*p2->p_cred)); 391 p2->p_cred->p_refcnt = 1; 392 crhold(p1->p_ucred); 393 uihold(p1->p_cred->p_uidinfo); 394 395 if (p2->p_prison) { 396 p2->p_prison->pr_ref++; 397 p2->p_flag |= P_JAILED; 398 } 399 400 if (p2->p_args) 401 p2->p_args->ar_ref++; 402 403 if (flags & RFSIGSHARE) { 404 p2->p_procsig = p1->p_procsig; 405 p2->p_procsig->ps_refcnt++; 406 if (p1->p_sigacts == &p1->p_addr->u_sigacts) { 407 struct sigacts *newsigacts; 408 int s; 409 410 /* Create the shared sigacts structure */ 411 MALLOC(newsigacts, struct sigacts *, 412 sizeof(struct sigacts), M_SUBPROC, M_WAITOK); 413 s = splhigh(); 414 /* 415 * Set p_sigacts to the new shared structure. 416 * Note that this is updating p1->p_sigacts at the 417 * same time, since p_sigacts is just a pointer to 418 * the shared p_procsig->ps_sigacts. 419 */ 420 p2->p_sigacts = newsigacts; 421 bcopy(&p1->p_addr->u_sigacts, p2->p_sigacts, 422 sizeof(*p2->p_sigacts)); 423 *p2->p_sigacts = p1->p_addr->u_sigacts; 424 splx(s); 425 } 426 } else { 427 MALLOC(p2->p_procsig, struct procsig *, sizeof(struct procsig), 428 M_SUBPROC, M_WAITOK); 429 bcopy(p1->p_procsig, p2->p_procsig, sizeof(*p2->p_procsig)); 430 p2->p_procsig->ps_refcnt = 1; 431 p2->p_sigacts = NULL; /* finished in vm_fork() */ 432 } 433 if (flags & RFLINUXTHPN) 434 p2->p_sigparent = SIGUSR1; 435 else 436 p2->p_sigparent = SIGCHLD; 437 438 /* bump references to the text vnode (for procfs) */ 439 p2->p_textvp = p1->p_textvp; 440 if (p2->p_textvp) 441 VREF(p2->p_textvp); 442 443 if (flags & RFCFDG) 444 p2->p_fd = fdinit(p1); 445 else if (flags & RFFDG) 446 p2->p_fd = fdcopy(p1); 447 else 448 p2->p_fd = fdshare(p1); 449 450 /* 451 * If p_limit is still copy-on-write, bump refcnt, 452 * otherwise get a copy that won't be modified. 453 * (If PL_SHAREMOD is clear, the structure is shared 454 * copy-on-write.) 455 */ 456 if (p1->p_limit->p_lflags & PL_SHAREMOD) 457 p2->p_limit = limcopy(p1->p_limit); 458 else { 459 p2->p_limit = p1->p_limit; 460 p2->p_limit->p_refcnt++; 461 } 462 463 /* 464 * Preserve some more flags in subprocess. P_PROFIL has already 465 * been preserved. 466 */ 467 p2->p_flag |= p1->p_flag & P_SUGID; 468 if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT) 469 p2->p_flag |= P_CONTROLT; 470 if (flags & RFPPWAIT) 471 p2->p_flag |= P_PPWAIT; 472 473 LIST_INSERT_AFTER(p1, p2, p_pglist); 474 475 /* 476 * Attach the new process to its parent. 477 * 478 * If RFNOWAIT is set, the newly created process becomes a child 479 * of init. This effectively disassociates the child from the 480 * parent. 481 */ 482 if (flags & RFNOWAIT) 483 pptr = initproc; 484 else 485 pptr = p1; 486 PROCTREE_LOCK(PT_EXCLUSIVE); 487 p2->p_pptr = pptr; 488 LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling); 489 PROCTREE_LOCK(PT_RELEASE); 490 LIST_INIT(&p2->p_children); 491 LIST_INIT(&p2->p_heldmtx); 492 LIST_INIT(&p2->p_contested); 493 494 callout_init(&p2->p_itcallout, 0); 495 callout_init(&p2->p_slpcallout, 1); 496 497 #ifdef KTRACE 498 /* 499 * Copy traceflag and tracefile if enabled. 500 * If not inherited, these were zeroed above. 501 */ 502 if (p1->p_traceflag&KTRFAC_INHERIT) { 503 p2->p_traceflag = p1->p_traceflag; 504 if ((p2->p_tracep = p1->p_tracep) != NULL) 505 VREF(p2->p_tracep); 506 } 507 #endif 508 509 /* 510 * set priority of child to be that of parent 511 */ 512 p2->p_estcpu = p1->p_estcpu; 513 514 /* 515 * This begins the section where we must prevent the parent 516 * from being swapped. 517 */ 518 PHOLD(p1); 519 520 /* 521 * Finish creating the child process. It will return via a different 522 * execution path later. (ie: directly into user mode) 523 */ 524 vm_fork(p1, p2, flags); 525 526 if (flags == (RFFDG | RFPROC)) { 527 cnt.v_forks++; 528 cnt.v_forkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 529 } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM)) { 530 cnt.v_vforks++; 531 cnt.v_vforkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 532 } else if (p1 == &proc0) { 533 cnt.v_kthreads++; 534 cnt.v_kthreadpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 535 } else { 536 cnt.v_rforks++; 537 cnt.v_rforkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 538 } 539 540 /* 541 * Both processes are set up, now check if any loadable modules want 542 * to adjust anything. 543 * What if they have an error? XXX 544 */ 545 TAILQ_FOREACH(ep, &fork_list, next) { 546 (*ep->function)(p1, p2, flags); 547 } 548 549 /* 550 * If RFSTOPPED not requested, make child runnable and add to 551 * run queue. 552 */ 553 microtime(&(p2->p_stats->p_start)); 554 p2->p_acflag = AFORK; 555 if ((flags & RFSTOPPED) == 0) { 556 splhigh(); 557 mtx_enter(&sched_lock, MTX_SPIN); 558 p2->p_stat = SRUN; 559 setrunqueue(p2); 560 mtx_exit(&sched_lock, MTX_SPIN); 561 spl0(); 562 } 563 564 /* 565 * Now can be swapped. 566 */ 567 PRELE(p1); 568 569 /* 570 * tell any interested parties about the new process 571 */ 572 KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid); 573 574 /* 575 * Preserve synchronization semantics of vfork. If waiting for 576 * child to exec or exit, set P_PPWAIT on child, and sleep on our 577 * proc (in case of exit). 578 */ 579 while (p2->p_flag & P_PPWAIT) 580 tsleep(p1, PWAIT, "ppwait", 0); 581 582 /* 583 * Return child proc pointer to parent. 584 */ 585 *procp = p2; 586 return (0); 587 } 588 589 /* 590 * The next two functionms are general routines to handle adding/deleting 591 * items on the fork callout list. 592 * 593 * at_fork(): 594 * Take the arguments given and put them onto the fork callout list, 595 * However first make sure that it's not already there. 596 * Returns 0 on success or a standard error number. 597 */ 598 599 int 600 at_fork(function) 601 forklist_fn function; 602 { 603 struct forklist *ep; 604 605 #ifdef INVARIANTS 606 /* let the programmer know if he's been stupid */ 607 if (rm_at_fork(function)) 608 printf("WARNING: fork callout entry (%p) already present\n", 609 function); 610 #endif 611 ep = malloc(sizeof(*ep), M_ATFORK, M_NOWAIT); 612 if (ep == NULL) 613 return (ENOMEM); 614 ep->function = function; 615 TAILQ_INSERT_TAIL(&fork_list, ep, next); 616 return (0); 617 } 618 619 /* 620 * Scan the exit callout list for the given item and remove it.. 621 * Returns the number of items removed (0 or 1) 622 */ 623 624 int 625 rm_at_fork(function) 626 forklist_fn function; 627 { 628 struct forklist *ep; 629 630 TAILQ_FOREACH(ep, &fork_list, next) { 631 if (ep->function == function) { 632 TAILQ_REMOVE(&fork_list, ep, next); 633 free(ep, M_ATFORK); 634 return(1); 635 } 636 } 637 return (0); 638 } 639 640 /* 641 * Handle the return of a child process from fork1(). This function 642 * is called from the MD fork_trampoline() entry point. 643 */ 644 void 645 fork_exit(callout, arg, frame) 646 void (*callout)(void *, struct trapframe *); 647 void *arg; 648 struct trapframe *frame; 649 { 650 struct proc *p; 651 652 mtx_exit(&sched_lock, MTX_SPIN); 653 /* 654 * XXX: We really shouldn't have to do this. 655 */ 656 enable_intr(); 657 658 #ifdef SMP 659 if (PCPU_GET(switchtime.tv_sec) == 0) 660 microuptime(PCPU_PTR(switchtime)); 661 PCPU_SET(switchticks, ticks); 662 #endif 663 664 /* 665 * cpu_set_fork_handler intercepts this function call to 666 * have this call a non-return function to stay in kernel mode. 667 * initproc has its own fork handler, but it does return. 668 */ 669 callout(arg, frame); 670 671 /* 672 * Check if a kernel thread misbehaved and returned from its main 673 * function. 674 */ 675 p = CURPROC; 676 if (p->p_flag & P_KTHREAD) { 677 mtx_enter(&Giant, MTX_DEF); 678 printf("Kernel thread \"%s\" (pid %d) exited prematurely.\n", 679 p->p_comm, p->p_pid); 680 kthread_exit(0); 681 } 682 mtx_assert(&Giant, MA_NOTOWNED); 683 } 684 685 /* 686 * Simplified back end of syscall(), used when returning from fork() 687 * directly into user mode. Giant is not held on entry, and must not 688 * be held on return. This function is passed in to fork_exit() as the 689 * first parameter and is called when returning to a new userland process. 690 */ 691 void 692 fork_return(p, frame) 693 struct proc *p; 694 struct trapframe *frame; 695 { 696 697 userret(p, frame, 0); 698 #ifdef KTRACE 699 if (KTRPOINT(p, KTR_SYSRET)) { 700 if (!mtx_owned(&Giant)) 701 mtx_enter(&Giant, MTX_DEF); 702 ktrsysret(p->p_tracep, SYS_fork, 0, 0); 703 } 704 #endif 705 if (mtx_owned(&Giant)) 706 mtx_exit(&Giant, MTX_DEF); 707 mtx_assert(&Giant, MA_NOTOWNED); 708 } 709