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