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 #include <sys/mplock2.h> 72 73 static MALLOC_DEFINE(M_ATFORK, "atfork", "atfork callback"); 74 75 /* 76 * These are the stuctures used to create a callout list for things to do 77 * when forking a process 78 */ 79 struct forklist { 80 forklist_fn function; 81 TAILQ_ENTRY(forklist) next; 82 }; 83 84 TAILQ_HEAD(forklist_head, forklist); 85 static struct forklist_head fork_list = TAILQ_HEAD_INITIALIZER(fork_list); 86 87 static struct lwp *lwp_fork(struct lwp *, struct proc *, int flags); 88 89 int forksleep; /* Place for fork1() to sleep on. */ 90 91 /* 92 * Red-Black tree support for LWPs 93 */ 94 95 static int 96 rb_lwp_compare(struct lwp *lp1, struct lwp *lp2) 97 { 98 if (lp1->lwp_tid < lp2->lwp_tid) 99 return(-1); 100 if (lp1->lwp_tid > lp2->lwp_tid) 101 return(1); 102 return(0); 103 } 104 105 RB_GENERATE2(lwp_rb_tree, lwp, u.lwp_rbnode, rb_lwp_compare, lwpid_t, lwp_tid); 106 107 /* 108 * Fork system call 109 * 110 * MPALMOSTSAFE 111 */ 112 int 113 sys_fork(struct fork_args *uap) 114 { 115 struct lwp *lp = curthread->td_lwp; 116 struct proc *p2; 117 int error; 118 119 get_mplock(); 120 error = fork1(lp, RFFDG | RFPROC | RFPGLOCK, &p2); 121 if (error == 0) { 122 start_forked_proc(lp, p2); 123 uap->sysmsg_fds[0] = p2->p_pid; 124 uap->sysmsg_fds[1] = 0; 125 } 126 rel_mplock(); 127 return error; 128 } 129 130 /* 131 * MPALMOSTSAFE 132 */ 133 int 134 sys_vfork(struct vfork_args *uap) 135 { 136 struct lwp *lp = curthread->td_lwp; 137 struct proc *p2; 138 int error; 139 140 get_mplock(); 141 error = fork1(lp, RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK, &p2); 142 if (error == 0) { 143 start_forked_proc(lp, p2); 144 uap->sysmsg_fds[0] = p2->p_pid; 145 uap->sysmsg_fds[1] = 0; 146 } 147 rel_mplock(); 148 return error; 149 } 150 151 /* 152 * Handle rforks. An rfork may (1) operate on the current process without 153 * creating a new, (2) create a new process that shared the current process's 154 * vmspace, signals, and/or descriptors, or (3) create a new process that does 155 * not share these things (normal fork). 156 * 157 * Note that we only call start_forked_proc() if a new process is actually 158 * created. 159 * 160 * rfork { int flags } 161 * 162 * MPALMOSTSAFE 163 */ 164 int 165 sys_rfork(struct rfork_args *uap) 166 { 167 struct lwp *lp = curthread->td_lwp; 168 struct proc *p2; 169 int error; 170 171 if ((uap->flags & RFKERNELONLY) != 0) 172 return (EINVAL); 173 174 get_mplock(); 175 error = fork1(lp, uap->flags | RFPGLOCK, &p2); 176 if (error == 0) { 177 if (p2) 178 start_forked_proc(lp, p2); 179 uap->sysmsg_fds[0] = p2 ? p2->p_pid : 0; 180 uap->sysmsg_fds[1] = 0; 181 } 182 rel_mplock(); 183 return error; 184 } 185 186 /* 187 * MPALMOSTSAFE 188 */ 189 int 190 sys_lwp_create(struct lwp_create_args *uap) 191 { 192 struct proc *p = curproc; 193 struct lwp *lp; 194 struct lwp_params params; 195 int error; 196 197 error = copyin(uap->params, ¶ms, sizeof(params)); 198 if (error) 199 goto fail2; 200 201 get_mplock(); 202 plimit_lwp_fork(p); /* force exclusive access */ 203 lp = lwp_fork(curthread->td_lwp, p, RFPROC); 204 error = cpu_prepare_lwp(lp, ¶ms); 205 if (params.tid1 != NULL && 206 (error = copyout(&lp->lwp_tid, params.tid1, sizeof(lp->lwp_tid)))) 207 goto fail; 208 if (params.tid2 != NULL && 209 (error = copyout(&lp->lwp_tid, params.tid2, sizeof(lp->lwp_tid)))) 210 goto fail; 211 212 /* 213 * Now schedule the new lwp. 214 */ 215 p->p_usched->resetpriority(lp); 216 crit_enter(); 217 lp->lwp_stat = LSRUN; 218 p->p_usched->setrunqueue(lp); 219 crit_exit(); 220 rel_mplock(); 221 222 return (0); 223 224 fail: 225 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp); 226 --p->p_nthreads; 227 /* lwp_dispose expects an exited lwp, and a held proc */ 228 lp->lwp_flag |= LWP_WEXIT; 229 lp->lwp_thread->td_flags |= TDF_EXITING; 230 PHOLD(p); 231 lwp_dispose(lp); 232 rel_mplock(); 233 fail2: 234 return (error); 235 } 236 237 int nprocs = 1; /* process 0 */ 238 239 int 240 fork1(struct lwp *lp1, int flags, struct proc **procp) 241 { 242 struct proc *p1 = lp1->lwp_proc; 243 struct proc *p2, *pptr; 244 struct pgrp *pgrp; 245 uid_t uid; 246 int ok, error; 247 static int curfail = 0; 248 static struct timeval lastfail; 249 struct forklist *ep; 250 struct filedesc_to_leader *fdtol; 251 252 if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG)) 253 return (EINVAL); 254 255 /* 256 * Here we don't create a new process, but we divorce 257 * certain parts of a process from itself. 258 */ 259 if ((flags & RFPROC) == 0) { 260 /* 261 * This kind of stunt does not work anymore if 262 * there are native threads (lwps) running 263 */ 264 if (p1->p_nthreads != 1) 265 return (EINVAL); 266 267 vm_fork(p1, 0, flags); 268 269 /* 270 * Close all file descriptors. 271 */ 272 if (flags & RFCFDG) { 273 struct filedesc *fdtmp; 274 fdtmp = fdinit(p1); 275 fdfree(p1, fdtmp); 276 } 277 278 /* 279 * Unshare file descriptors (from parent.) 280 */ 281 if (flags & RFFDG) { 282 if (p1->p_fd->fd_refcnt > 1) { 283 struct filedesc *newfd; 284 newfd = fdcopy(p1); 285 fdfree(p1, newfd); 286 } 287 } 288 *procp = NULL; 289 return (0); 290 } 291 292 /* 293 * Interlock against process group signal delivery. If signals 294 * are pending after the interlock is obtained we have to restart 295 * the system call to process the signals. If we don't the child 296 * can miss a pgsignal (such as ^C) sent during the fork. 297 * 298 * We can't use CURSIG() here because it will process any STOPs 299 * and cause the process group lock to be held indefinitely. If 300 * a STOP occurs, the fork will be restarted after the CONT. 301 */ 302 error = 0; 303 pgrp = NULL; 304 if ((flags & RFPGLOCK) && (pgrp = p1->p_pgrp) != NULL) { 305 lockmgr(&pgrp->pg_lock, LK_SHARED); 306 if (CURSIG_NOBLOCK(lp1)) { 307 error = ERESTART; 308 goto done; 309 } 310 } 311 312 /* 313 * Although process entries are dynamically created, we still keep 314 * a global limit on the maximum number we will create. Don't allow 315 * a nonprivileged user to use the last ten processes; don't let root 316 * exceed the limit. The variable nprocs is the current number of 317 * processes, maxproc is the limit. 318 */ 319 uid = lp1->lwp_thread->td_ucred->cr_ruid; 320 if ((nprocs >= maxproc - 10 && uid != 0) || nprocs >= maxproc) { 321 if (ppsratecheck(&lastfail, &curfail, 1)) 322 kprintf("maxproc limit exceeded by uid %d, please " 323 "see tuning(7) and login.conf(5).\n", uid); 324 tsleep(&forksleep, 0, "fork", hz / 2); 325 error = EAGAIN; 326 goto done; 327 } 328 /* 329 * Increment the nprocs resource before blocking can occur. There 330 * are hard-limits as to the number of processes that can run. 331 */ 332 nprocs++; 333 334 /* 335 * Increment the count of procs running with this uid. Don't allow 336 * a nonprivileged user to exceed their current limit. 337 */ 338 ok = chgproccnt(lp1->lwp_thread->td_ucred->cr_ruidinfo, 1, 339 (uid != 0) ? p1->p_rlimit[RLIMIT_NPROC].rlim_cur : 0); 340 if (!ok) { 341 /* 342 * Back out the process count 343 */ 344 nprocs--; 345 if (ppsratecheck(&lastfail, &curfail, 1)) 346 kprintf("maxproc limit exceeded by uid %d, please " 347 "see tuning(7) and login.conf(5).\n", uid); 348 tsleep(&forksleep, 0, "fork", hz / 2); 349 error = EAGAIN; 350 goto done; 351 } 352 353 /* Allocate new proc. */ 354 p2 = kmalloc(sizeof(struct proc), M_PROC, M_WAITOK|M_ZERO); 355 356 /* 357 * Setup linkage for kernel based threading XXX lwp 358 */ 359 if (flags & RFTHREAD) { 360 p2->p_peers = p1->p_peers; 361 p1->p_peers = p2; 362 p2->p_leader = p1->p_leader; 363 } else { 364 p2->p_leader = p2; 365 } 366 367 RB_INIT(&p2->p_lwp_tree); 368 spin_init(&p2->p_spin); 369 p2->p_lasttid = -1; /* first tid will be 0 */ 370 371 /* 372 * Setting the state to SIDL protects the partially initialized 373 * process once it starts getting hooked into the rest of the system. 374 */ 375 p2->p_stat = SIDL; 376 proc_add_allproc(p2); 377 378 /* 379 * Make a proc table entry for the new process. 380 * The whole structure was zeroed above, so copy the section that is 381 * copied directly from the parent. 382 */ 383 bcopy(&p1->p_startcopy, &p2->p_startcopy, 384 (unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy)); 385 386 /* 387 * Duplicate sub-structures as needed. 388 * Increase reference counts on shared objects. 389 */ 390 if (p1->p_flag & P_PROFIL) 391 startprofclock(p2); 392 p2->p_ucred = crhold(lp1->lwp_thread->td_ucred); 393 KKASSERT(p2->p_lock == 0); 394 395 if (jailed(p2->p_ucred)) 396 p2->p_flag |= P_JAILED; 397 398 if (p2->p_args) 399 p2->p_args->ar_ref++; 400 401 p2->p_usched = p1->p_usched; 402 403 if (flags & RFSIGSHARE) { 404 p2->p_sigacts = p1->p_sigacts; 405 p2->p_sigacts->ps_refcnt++; 406 } else { 407 p2->p_sigacts = (struct sigacts *)kmalloc(sizeof(*p2->p_sigacts), 408 M_SUBPROC, M_WAITOK); 409 bcopy(p1->p_sigacts, p2->p_sigacts, sizeof(*p2->p_sigacts)); 410 p2->p_sigacts->ps_refcnt = 1; 411 } 412 if (flags & RFLINUXTHPN) 413 p2->p_sigparent = SIGUSR1; 414 else 415 p2->p_sigparent = SIGCHLD; 416 417 /* bump references to the text vnode (for procfs) */ 418 p2->p_textvp = p1->p_textvp; 419 if (p2->p_textvp) 420 vref(p2->p_textvp); 421 422 /* copy namecache handle to the text file */ 423 if (p1->p_textnch.mount) 424 cache_copy(&p1->p_textnch, &p2->p_textnch); 425 426 /* 427 * Handle file descriptors 428 */ 429 if (flags & RFCFDG) { 430 p2->p_fd = fdinit(p1); 431 fdtol = NULL; 432 } else if (flags & RFFDG) { 433 p2->p_fd = fdcopy(p1); 434 fdtol = NULL; 435 } else { 436 p2->p_fd = fdshare(p1); 437 if (p1->p_fdtol == NULL) 438 p1->p_fdtol = 439 filedesc_to_leader_alloc(NULL, 440 p1->p_leader); 441 if ((flags & RFTHREAD) != 0) { 442 /* 443 * Shared file descriptor table and 444 * shared process leaders. 445 */ 446 fdtol = p1->p_fdtol; 447 fdtol->fdl_refcount++; 448 } else { 449 /* 450 * Shared file descriptor table, and 451 * different process leaders 452 */ 453 fdtol = filedesc_to_leader_alloc(p1->p_fdtol, p2); 454 } 455 } 456 p2->p_fdtol = fdtol; 457 p2->p_limit = plimit_fork(p1); 458 459 /* 460 * Preserve some more flags in subprocess. P_PROFIL has already 461 * been preserved. 462 */ 463 p2->p_flag |= p1->p_flag & P_SUGID; 464 if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT) 465 p2->p_flag |= P_CONTROLT; 466 if (flags & RFPPWAIT) 467 p2->p_flag |= P_PPWAIT; 468 469 /* 470 * Inherit the virtual kernel structure (allows a virtual kernel 471 * to fork to simulate multiple cpus). 472 */ 473 if (p1->p_vkernel) 474 vkernel_inherit(p1, p2); 475 476 /* 477 * Once we are on a pglist we may receive signals. XXX we might 478 * race a ^C being sent to the process group by not receiving it 479 * at all prior to this line. 480 */ 481 LIST_INSERT_AFTER(p1, p2, p_pglist); 482 483 /* 484 * Attach the new process to its parent. 485 * 486 * If RFNOWAIT is set, the newly created process becomes a child 487 * of init. This effectively disassociates the child from the 488 * parent. 489 */ 490 if (flags & RFNOWAIT) 491 pptr = initproc; 492 else 493 pptr = p1; 494 p2->p_pptr = pptr; 495 LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling); 496 LIST_INIT(&p2->p_children); 497 varsymset_init(&p2->p_varsymset, &p1->p_varsymset); 498 callout_init(&p2->p_ithandle); 499 500 #ifdef KTRACE 501 /* 502 * Copy traceflag and tracefile if enabled. If not inherited, 503 * these were zeroed above but we still could have a trace race 504 * so make sure p2's p_tracenode is NULL. 505 */ 506 if ((p1->p_traceflag & KTRFAC_INHERIT) && p2->p_tracenode == NULL) { 507 p2->p_traceflag = p1->p_traceflag; 508 p2->p_tracenode = ktrinherit(p1->p_tracenode); 509 } 510 #endif 511 512 /* 513 * This begins the section where we must prevent the parent 514 * from being swapped. 515 * 516 * Gets PRELE'd in the caller in start_forked_proc(). 517 */ 518 PHOLD(p1); 519 520 vm_fork(p1, p2, flags); 521 522 /* 523 * Create the first lwp associated with the new proc. 524 * It will return via a different execution path later, directly 525 * into userland, after it was put on the runq by 526 * start_forked_proc(). 527 */ 528 lwp_fork(lp1, p2, flags); 529 530 if (flags == (RFFDG | RFPROC | RFPGLOCK)) { 531 mycpu->gd_cnt.v_forks++; 532 mycpu->gd_cnt.v_forkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 533 } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK)) { 534 mycpu->gd_cnt.v_vforks++; 535 mycpu->gd_cnt.v_vforkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 536 } else if (p1 == &proc0) { 537 mycpu->gd_cnt.v_kthreads++; 538 mycpu->gd_cnt.v_kthreadpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 539 } else { 540 mycpu->gd_cnt.v_rforks++; 541 mycpu->gd_cnt.v_rforkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 542 } 543 544 /* 545 * Both processes are set up, now check if any loadable modules want 546 * to adjust anything. 547 * What if they have an error? XXX 548 */ 549 TAILQ_FOREACH(ep, &fork_list, next) { 550 (*ep->function)(p1, p2, flags); 551 } 552 553 /* 554 * Set the start time. Note that the process is not runnable. The 555 * caller is responsible for making it runnable. 556 */ 557 microtime(&p2->p_start); 558 p2->p_acflag = AFORK; 559 560 /* 561 * tell any interested parties about the new process 562 */ 563 KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid); 564 565 /* 566 * Return child proc pointer to parent. 567 */ 568 *procp = p2; 569 done: 570 if (pgrp) 571 lockmgr(&pgrp->pg_lock, LK_RELEASE); 572 return (error); 573 } 574 575 static struct lwp * 576 lwp_fork(struct lwp *origlp, struct proc *destproc, int flags) 577 { 578 struct lwp *lp; 579 struct thread *td; 580 581 lp = kmalloc(sizeof(struct lwp), M_LWP, M_WAITOK|M_ZERO); 582 583 lp->lwp_proc = destproc; 584 lp->lwp_vmspace = destproc->p_vmspace; 585 lp->lwp_stat = LSRUN; 586 bcopy(&origlp->lwp_startcopy, &lp->lwp_startcopy, 587 (unsigned) ((caddr_t)&lp->lwp_endcopy - 588 (caddr_t)&lp->lwp_startcopy)); 589 lp->lwp_flag |= origlp->lwp_flag & LWP_ALTSTACK; 590 /* 591 * Set cpbase to the last timeout that occured (not the upcoming 592 * timeout). 593 * 594 * A critical section is required since a timer IPI can update 595 * scheduler specific data. 596 */ 597 crit_enter(); 598 lp->lwp_cpbase = mycpu->gd_schedclock.time - 599 mycpu->gd_schedclock.periodic; 600 destproc->p_usched->heuristic_forking(origlp, lp); 601 crit_exit(); 602 lp->lwp_cpumask &= usched_mastermask; 603 604 /* 605 * Assign a TID to the lp. Loop until the insert succeeds (returns 606 * NULL). 607 */ 608 lp->lwp_tid = destproc->p_lasttid; 609 do { 610 if (++lp->lwp_tid < 0) 611 lp->lwp_tid = 1; 612 } while (lwp_rb_tree_RB_INSERT(&destproc->p_lwp_tree, lp) != NULL); 613 destproc->p_lasttid = lp->lwp_tid; 614 destproc->p_nthreads++; 615 616 td = lwkt_alloc_thread(NULL, LWKT_THREAD_STACK, -1, 0); 617 lp->lwp_thread = td; 618 td->td_proc = destproc; 619 td->td_lwp = lp; 620 td->td_switch = cpu_heavy_switch; 621 #ifdef SMP 622 KKASSERT(td->td_mpcount == 1); 623 #endif 624 lwkt_setpri(td, TDPRI_KERN_USER); 625 lwkt_set_comm(td, "%s", destproc->p_comm); 626 627 /* 628 * cpu_fork will copy and update the pcb, set up the kernel stack, 629 * and make the child ready to run. 630 */ 631 cpu_fork(origlp, lp, flags); 632 caps_fork(origlp->lwp_thread, lp->lwp_thread); 633 kqueue_init(&lp->lwp_kqueue, destproc->p_fd); 634 635 return (lp); 636 } 637 638 /* 639 * The next two functionms are general routines to handle adding/deleting 640 * items on the fork callout list. 641 * 642 * at_fork(): 643 * Take the arguments given and put them onto the fork callout list, 644 * However first make sure that it's not already there. 645 * Returns 0 on success or a standard error number. 646 */ 647 int 648 at_fork(forklist_fn function) 649 { 650 struct forklist *ep; 651 652 #ifdef INVARIANTS 653 /* let the programmer know if he's been stupid */ 654 if (rm_at_fork(function)) { 655 kprintf("WARNING: fork callout entry (%p) already present\n", 656 function); 657 } 658 #endif 659 ep = kmalloc(sizeof(*ep), M_ATFORK, M_WAITOK|M_ZERO); 660 ep->function = function; 661 TAILQ_INSERT_TAIL(&fork_list, ep, next); 662 return (0); 663 } 664 665 /* 666 * Scan the exit callout list for the given item and remove it.. 667 * Returns the number of items removed (0 or 1) 668 */ 669 int 670 rm_at_fork(forklist_fn function) 671 { 672 struct forklist *ep; 673 674 TAILQ_FOREACH(ep, &fork_list, next) { 675 if (ep->function == function) { 676 TAILQ_REMOVE(&fork_list, ep, next); 677 kfree(ep, M_ATFORK); 678 return(1); 679 } 680 } 681 return (0); 682 } 683 684 /* 685 * Add a forked process to the run queue after any remaining setup, such 686 * as setting the fork handler, has been completed. 687 */ 688 void 689 start_forked_proc(struct lwp *lp1, struct proc *p2) 690 { 691 struct lwp *lp2 = ONLY_LWP_IN_PROC(p2); 692 693 /* 694 * Move from SIDL to RUN queue, and activate the process's thread. 695 * Activation of the thread effectively makes the process "a" 696 * current process, so we do not setrunqueue(). 697 * 698 * YYY setrunqueue works here but we should clean up the trampoline 699 * code so we just schedule the LWKT thread and let the trampoline 700 * deal with the userland scheduler on return to userland. 701 */ 702 KASSERT(p2->p_stat == SIDL, 703 ("cannot start forked process, bad status: %p", p2)); 704 p2->p_usched->resetpriority(lp2); 705 crit_enter(); 706 p2->p_stat = SACTIVE; 707 lp2->lwp_stat = LSRUN; 708 p2->p_usched->setrunqueue(lp2); 709 crit_exit(); 710 711 /* 712 * Now can be swapped. 713 */ 714 PRELE(lp1->lwp_proc); 715 716 /* 717 * Preserve synchronization semantics of vfork. If waiting for 718 * child to exec or exit, set P_PPWAIT on child, and sleep on our 719 * proc (in case of exit). 720 */ 721 while (p2->p_flag & P_PPWAIT) 722 tsleep(lp1->lwp_proc, 0, "ppwait", 0); 723 } 724