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 * Fork system call 108 * 109 * MPALMOSTSAFE 110 */ 111 int 112 sys_fork(struct fork_args *uap) 113 { 114 struct lwp *lp = curthread->td_lwp; 115 struct proc *p2; 116 int error; 117 118 get_mplock(); 119 error = fork1(lp, RFFDG | RFPROC | RFPGLOCK, &p2); 120 if (error == 0) { 121 start_forked_proc(lp, p2); 122 uap->sysmsg_fds[0] = p2->p_pid; 123 uap->sysmsg_fds[1] = 0; 124 } 125 rel_mplock(); 126 return error; 127 } 128 129 /* 130 * MPALMOSTSAFE 131 */ 132 int 133 sys_vfork(struct vfork_args *uap) 134 { 135 struct lwp *lp = curthread->td_lwp; 136 struct proc *p2; 137 int error; 138 139 get_mplock(); 140 error = fork1(lp, RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK, &p2); 141 if (error == 0) { 142 start_forked_proc(lp, p2); 143 uap->sysmsg_fds[0] = p2->p_pid; 144 uap->sysmsg_fds[1] = 0; 145 } 146 rel_mplock(); 147 return error; 148 } 149 150 /* 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 } 160 * 161 * MPALMOSTSAFE 162 */ 163 int 164 sys_rfork(struct rfork_args *uap) 165 { 166 struct lwp *lp = curthread->td_lwp; 167 struct proc *p2; 168 int error; 169 170 if ((uap->flags & RFKERNELONLY) != 0) 171 return (EINVAL); 172 173 get_mplock(); 174 error = fork1(lp, uap->flags | RFPGLOCK, &p2); 175 if (error == 0) { 176 if (p2) 177 start_forked_proc(lp, p2); 178 uap->sysmsg_fds[0] = p2 ? p2->p_pid : 0; 179 uap->sysmsg_fds[1] = 0; 180 } 181 rel_mplock(); 182 return error; 183 } 184 185 /* 186 * MPALMOSTSAFE 187 */ 188 int 189 sys_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, ¶ms, sizeof(params)); 197 if (error) 198 goto fail2; 199 200 get_mplock(); 201 plimit_lwp_fork(p); /* force exclusive access */ 202 lp = lwp_fork(curthread->td_lwp, p, RFPROC); 203 error = cpu_prepare_lwp(lp, ¶ms); 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 /* 212 * Now schedule the new lwp. 213 */ 214 p->p_usched->resetpriority(lp); 215 crit_enter(); 216 lp->lwp_stat = LSRUN; 217 p->p_usched->setrunqueue(lp); 218 crit_exit(); 219 rel_mplock(); 220 221 return (0); 222 223 fail: 224 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp); 225 --p->p_nthreads; 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); 230 lwp_dispose(lp); 231 rel_mplock(); 232 fail2: 233 return (error); 234 } 235 236 int nprocs = 1; /* process 0 */ 237 238 int 239 fork1(struct lwp *lp1, int flags, struct proc **procp) 240 { 241 struct proc *p1 = lp1->lwp_proc; 242 struct proc *p2, *pptr; 243 struct pgrp *pgrp; 244 uid_t uid; 245 int ok, error; 246 static int curfail = 0; 247 static struct timeval lastfail; 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) { 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); 267 268 /* 269 * Close all file descriptors. 270 */ 271 if (flags & RFCFDG) { 272 struct filedesc *fdtmp; 273 fdtmp = fdinit(p1); 274 fdfree(p1, fdtmp); 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); 284 fdfree(p1, newfd); 285 } 286 } 287 *procp = NULL; 288 return (0); 289 } 290 291 /* 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); 305 if (CURSIG_NOBLOCK(lp1)) { 306 error = ERESTART; 307 goto done; 308 } 309 } 310 311 /* 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 */ 318 uid = lp1->lwp_thread->td_ucred->cr_ruid; 319 if ((nprocs >= maxproc - 10 && uid != 0) || nprocs >= maxproc) { 320 if (ppsratecheck(&lastfail, &curfail, 1)) 321 kprintf("maxproc limit exceeded by uid %d, please " 322 "see tuning(7) and login.conf(5).\n", uid); 323 tsleep(&forksleep, 0, "fork", hz / 2); 324 error = EAGAIN; 325 goto done; 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 */ 337 ok = chgproccnt(lp1->lwp_thread->td_ucred->cr_ruidinfo, 1, 338 (uid != 0) ? p1->p_rlimit[RLIMIT_NPROC].rlim_cur : 0); 339 if (!ok) { 340 /* 341 * Back out the process count 342 */ 343 nprocs--; 344 if (ppsratecheck(&lastfail, &curfail, 1)) 345 kprintf("maxproc limit exceeded by uid %d, please " 346 "see tuning(7) and login.conf(5).\n", uid); 347 tsleep(&forksleep, 0, "fork", hz / 2); 348 error = EAGAIN; 349 goto done; 350 } 351 352 /* Allocate new proc. */ 353 p2 = kmalloc(sizeof(struct proc), M_PROC, M_WAITOK|M_ZERO); 354 355 /* 356 * Setup linkage for kernel based threading XXX lwp 357 */ 358 if (flags & RFTHREAD) { 359 p2->p_peers = p1->p_peers; 360 p1->p_peers = p2; 361 p2->p_leader = p1->p_leader; 362 } else { 363 p2->p_leader = p2; 364 } 365 366 RB_INIT(&p2->p_lwp_tree); 367 spin_init(&p2->p_spin); 368 p2->p_lasttid = -1; /* first tid will be 0 */ 369 370 /* 371 * Setting the state to SIDL protects the partially initialized 372 * process once it starts getting hooked into the rest of the system. 373 */ 374 p2->p_stat = SIDL; 375 proc_add_allproc(p2); 376 377 /* 378 * Make a proc table entry for the new process. 379 * The whole structure was zeroed above, so copy the section that is 380 * copied directly from the parent. 381 */ 382 bcopy(&p1->p_startcopy, &p2->p_startcopy, 383 (unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy)); 384 385 /* 386 * Duplicate sub-structures as needed. 387 * Increase reference counts on shared objects. 388 */ 389 if (p1->p_flag & P_PROFIL) 390 startprofclock(p2); 391 p2->p_ucred = crhold(lp1->lwp_thread->td_ucred); 392 KKASSERT(p2->p_lock == 0); 393 394 if (jailed(p2->p_ucred)) 395 p2->p_flag |= P_JAILED; 396 397 if (p2->p_args) 398 p2->p_args->ar_ref++; 399 400 p2->p_usched = p1->p_usched; 401 402 if (flags & RFSIGSHARE) { 403 p2->p_sigacts = p1->p_sigacts; 404 p2->p_sigacts->ps_refcnt++; 405 } else { 406 p2->p_sigacts = (struct sigacts *)kmalloc(sizeof(*p2->p_sigacts), 407 M_SUBPROC, M_WAITOK); 408 bcopy(p1->p_sigacts, p2->p_sigacts, sizeof(*p2->p_sigacts)); 409 p2->p_sigacts->ps_refcnt = 1; 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) 419 vref(p2->p_textvp); 420 421 /* 422 * Handle file descriptors 423 */ 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 */ 448 fdtol = filedesc_to_leader_alloc(p1->p_fdtol, p2); 449 } 450 } 451 p2->p_fdtol = fdtol; 452 p2->p_limit = plimit_fork(p1); 453 454 /* 455 * Preserve some more flags in subprocess. P_PROFIL has already 456 * been preserved. 457 */ 458 p2->p_flag |= p1->p_flag & P_SUGID; 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; 463 464 /* 465 * Inherit the virtual kernel structure (allows a virtual kernel 466 * to fork to simulate multiple cpus). 467 */ 468 if (p1->p_vkernel) 469 vkernel_inherit(p1, p2); 470 471 /* 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 */ 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); 492 varsymset_init(&p2->p_varsymset, &p1->p_varsymset); 493 callout_init(&p2->p_ithandle); 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 499 * so make sure p2's p_tracenode is NULL. 500 */ 501 if ((p1->p_traceflag & KTRFAC_INHERIT) && p2->p_tracenode == NULL) { 502 p2->p_traceflag = p1->p_traceflag; 503 p2->p_tracenode = ktrinherit(p1->p_tracenode); 504 } 505 #endif 506 507 /* 508 * This begins the section where we must prevent the parent 509 * from being swapped. 510 * 511 * Gets PRELE'd in the caller in start_forked_proc(). 512 */ 513 PHOLD(p1); 514 515 vm_fork(p1, p2, flags); 516 517 /* 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(). 522 */ 523 lwp_fork(lp1, p2, flags); 524 525 if (flags == (RFFDG | RFPROC | RFPGLOCK)) { 526 mycpu->gd_cnt.v_forks++; 527 mycpu->gd_cnt.v_forkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 528 } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK)) { 529 mycpu->gd_cnt.v_vforks++; 530 mycpu->gd_cnt.v_vforkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 531 } else if (p1 == &proc0) { 532 mycpu->gd_cnt.v_kthreads++; 533 mycpu->gd_cnt.v_kthreadpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 534 } else { 535 mycpu->gd_cnt.v_rforks++; 536 mycpu->gd_cnt.v_rforkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 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 /* 549 * Set the start time. Note that the process is not runnable. The 550 * caller is responsible for making it runnable. 551 */ 552 microtime(&p2->p_start); 553 p2->p_acflag = AFORK; 554 555 /* 556 * tell any interested parties about the new process 557 */ 558 KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid); 559 560 /* 561 * Return child proc pointer to parent. 562 */ 563 *procp = p2; 564 done: 565 if (pgrp) 566 lockmgr(&pgrp->pg_lock, LK_RELEASE); 567 return (error); 568 } 569 570 static struct lwp * 571 lwp_fork(struct lwp *origlp, struct proc *destproc, int flags) 572 { 573 struct lwp *lp; 574 struct thread *td; 575 576 lp = kmalloc(sizeof(struct lwp), M_LWP, M_WAITOK|M_ZERO); 577 578 lp->lwp_proc = destproc; 579 lp->lwp_vmspace = destproc->p_vmspace; 580 lp->lwp_stat = LSRUN; 581 bcopy(&origlp->lwp_startcopy, &lp->lwp_startcopy, 582 (unsigned) ((caddr_t)&lp->lwp_endcopy - 583 (caddr_t)&lp->lwp_startcopy)); 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(); 597 lp->lwp_cpumask &= usched_mastermask; 598 599 /* 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++; 610 611 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 } 631 632 /* 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 */ 641 int 642 at_fork(forklist_fn function) 643 { 644 struct forklist *ep; 645 646 #ifdef INVARIANTS 647 /* let the programmer know if he's been stupid */ 648 if (rm_at_fork(function)) { 649 kprintf("WARNING: fork callout entry (%p) already present\n", 650 function); 651 } 652 #endif 653 ep = kmalloc(sizeof(*ep), M_ATFORK, M_WAITOK|M_ZERO); 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 */ 663 int 664 rm_at_fork(forklist_fn function) 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); 671 kfree(ep, M_ATFORK); 672 return(1); 673 } 674 } 675 return (0); 676 } 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 */ 682 void 683 start_forked_proc(struct lwp *lp1, struct proc *p2) 684 { 685 struct lwp *lp2 = ONLY_LWP_IN_PROC(p2); 686 687 /* 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(). 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. 695 */ 696 KASSERT(p2->p_stat == SIDL, 697 ("cannot start forked process, bad status: %p", p2)); 698 p2->p_usched->resetpriority(lp2); 699 crit_enter(); 700 p2->p_stat = SACTIVE; 701 lp2->lwp_stat = LSRUN; 702 p2->p_usched->setrunqueue(lp2); 703 crit_exit(); 704 705 /* 706 * Now can be swapped. 707 */ 708 PRELE(lp1->lwp_proc); 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) 716 tsleep(lp1->lwp_proc, 0, "ppwait", 0); 717 } 718