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 #include <sys/dsched.h> 74 75 static MALLOC_DEFINE(M_ATFORK, "atfork", "atfork callback"); 76 77 /* 78 * These are the stuctures used to create a callout list for things to do 79 * when forking a process 80 */ 81 struct forklist { 82 forklist_fn function; 83 TAILQ_ENTRY(forklist) next; 84 }; 85 86 TAILQ_HEAD(forklist_head, forklist); 87 static struct forklist_head fork_list = TAILQ_HEAD_INITIALIZER(fork_list); 88 89 static struct lwp *lwp_fork(struct lwp *, struct proc *, int flags); 90 91 int forksleep; /* Place for fork1() to sleep on. */ 92 93 /* 94 * Red-Black tree support for LWPs 95 */ 96 97 static int 98 rb_lwp_compare(struct lwp *lp1, struct lwp *lp2) 99 { 100 if (lp1->lwp_tid < lp2->lwp_tid) 101 return(-1); 102 if (lp1->lwp_tid > lp2->lwp_tid) 103 return(1); 104 return(0); 105 } 106 107 RB_GENERATE2(lwp_rb_tree, lwp, u.lwp_rbnode, rb_lwp_compare, lwpid_t, lwp_tid); 108 109 /* 110 * Fork system call 111 * 112 * MPALMOSTSAFE 113 */ 114 int 115 sys_fork(struct fork_args *uap) 116 { 117 struct lwp *lp = curthread->td_lwp; 118 struct proc *p2; 119 int error; 120 121 get_mplock(); 122 error = fork1(lp, RFFDG | RFPROC | RFPGLOCK, &p2); 123 if (error == 0) { 124 start_forked_proc(lp, p2); 125 uap->sysmsg_fds[0] = p2->p_pid; 126 uap->sysmsg_fds[1] = 0; 127 } 128 rel_mplock(); 129 return error; 130 } 131 132 /* 133 * MPALMOSTSAFE 134 */ 135 int 136 sys_vfork(struct vfork_args *uap) 137 { 138 struct lwp *lp = curthread->td_lwp; 139 struct proc *p2; 140 int error; 141 142 get_mplock(); 143 error = fork1(lp, RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK, &p2); 144 if (error == 0) { 145 start_forked_proc(lp, p2); 146 uap->sysmsg_fds[0] = p2->p_pid; 147 uap->sysmsg_fds[1] = 0; 148 } 149 rel_mplock(); 150 return error; 151 } 152 153 /* 154 * Handle rforks. An rfork may (1) operate on the current process without 155 * creating a new, (2) create a new process that shared the current process's 156 * vmspace, signals, and/or descriptors, or (3) create a new process that does 157 * not share these things (normal fork). 158 * 159 * Note that we only call start_forked_proc() if a new process is actually 160 * created. 161 * 162 * rfork { int flags } 163 * 164 * MPALMOSTSAFE 165 */ 166 int 167 sys_rfork(struct rfork_args *uap) 168 { 169 struct lwp *lp = curthread->td_lwp; 170 struct proc *p2; 171 int error; 172 173 if ((uap->flags & RFKERNELONLY) != 0) 174 return (EINVAL); 175 176 get_mplock(); 177 error = fork1(lp, uap->flags | RFPGLOCK, &p2); 178 if (error == 0) { 179 if (p2) 180 start_forked_proc(lp, p2); 181 uap->sysmsg_fds[0] = p2 ? p2->p_pid : 0; 182 uap->sysmsg_fds[1] = 0; 183 } 184 rel_mplock(); 185 return error; 186 } 187 188 /* 189 * MPALMOSTSAFE 190 */ 191 int 192 sys_lwp_create(struct lwp_create_args *uap) 193 { 194 struct proc *p = curproc; 195 struct lwp *lp; 196 struct lwp_params params; 197 int error; 198 199 error = copyin(uap->params, ¶ms, sizeof(params)); 200 if (error) 201 goto fail2; 202 203 get_mplock(); 204 plimit_lwp_fork(p); /* force exclusive access */ 205 lp = lwp_fork(curthread->td_lwp, p, RFPROC); 206 error = cpu_prepare_lwp(lp, ¶ms); 207 if (params.tid1 != NULL && 208 (error = copyout(&lp->lwp_tid, params.tid1, sizeof(lp->lwp_tid)))) 209 goto fail; 210 if (params.tid2 != NULL && 211 (error = copyout(&lp->lwp_tid, params.tid2, sizeof(lp->lwp_tid)))) 212 goto fail; 213 214 /* 215 * Now schedule the new lwp. 216 */ 217 p->p_usched->resetpriority(lp); 218 crit_enter(); 219 lp->lwp_stat = LSRUN; 220 p->p_usched->setrunqueue(lp); 221 crit_exit(); 222 rel_mplock(); 223 224 return (0); 225 226 fail: 227 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp); 228 --p->p_nthreads; 229 /* lwp_dispose expects an exited lwp, and a held proc */ 230 lp->lwp_flag |= LWP_WEXIT; 231 lp->lwp_thread->td_flags |= TDF_EXITING; 232 PHOLD(p); 233 lwp_dispose(lp); 234 rel_mplock(); 235 fail2: 236 return (error); 237 } 238 239 int nprocs = 1; /* process 0 */ 240 241 int 242 fork1(struct lwp *lp1, int flags, struct proc **procp) 243 { 244 struct proc *p1 = lp1->lwp_proc; 245 struct proc *p2, *pptr; 246 struct pgrp *pgrp; 247 uid_t uid; 248 int ok, error; 249 static int curfail = 0; 250 static struct timeval lastfail; 251 struct forklist *ep; 252 struct filedesc_to_leader *fdtol; 253 254 if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG)) 255 return (EINVAL); 256 257 /* 258 * Here we don't create a new process, but we divorce 259 * certain parts of a process from itself. 260 */ 261 if ((flags & RFPROC) == 0) { 262 /* 263 * This kind of stunt does not work anymore if 264 * there are native threads (lwps) running 265 */ 266 if (p1->p_nthreads != 1) 267 return (EINVAL); 268 269 vm_fork(p1, 0, flags); 270 271 /* 272 * Close all file descriptors. 273 */ 274 if (flags & RFCFDG) { 275 struct filedesc *fdtmp; 276 fdtmp = fdinit(p1); 277 fdfree(p1, fdtmp); 278 } 279 280 /* 281 * Unshare file descriptors (from parent.) 282 */ 283 if (flags & RFFDG) { 284 if (p1->p_fd->fd_refcnt > 1) { 285 struct filedesc *newfd; 286 newfd = fdcopy(p1); 287 fdfree(p1, newfd); 288 } 289 } 290 *procp = NULL; 291 return (0); 292 } 293 294 /* 295 * Interlock against process group signal delivery. If signals 296 * are pending after the interlock is obtained we have to restart 297 * the system call to process the signals. If we don't the child 298 * can miss a pgsignal (such as ^C) sent during the fork. 299 * 300 * We can't use CURSIG() here because it will process any STOPs 301 * and cause the process group lock to be held indefinitely. If 302 * a STOP occurs, the fork will be restarted after the CONT. 303 */ 304 error = 0; 305 pgrp = NULL; 306 if ((flags & RFPGLOCK) && (pgrp = p1->p_pgrp) != NULL) { 307 lockmgr(&pgrp->pg_lock, LK_SHARED); 308 if (CURSIG_NOBLOCK(lp1)) { 309 error = ERESTART; 310 goto done; 311 } 312 } 313 314 /* 315 * Although process entries are dynamically created, we still keep 316 * a global limit on the maximum number we will create. Don't allow 317 * a nonprivileged user to use the last ten processes; don't let root 318 * exceed the limit. The variable nprocs is the current number of 319 * processes, maxproc is the limit. 320 */ 321 uid = lp1->lwp_thread->td_ucred->cr_ruid; 322 if ((nprocs >= maxproc - 10 && uid != 0) || nprocs >= maxproc) { 323 if (ppsratecheck(&lastfail, &curfail, 1)) 324 kprintf("maxproc limit exceeded by uid %d, please " 325 "see tuning(7) and login.conf(5).\n", uid); 326 tsleep(&forksleep, 0, "fork", hz / 2); 327 error = EAGAIN; 328 goto done; 329 } 330 /* 331 * Increment the nprocs resource before blocking can occur. There 332 * are hard-limits as to the number of processes that can run. 333 */ 334 nprocs++; 335 336 /* 337 * Increment the count of procs running with this uid. Don't allow 338 * a nonprivileged user to exceed their current limit. 339 */ 340 ok = chgproccnt(lp1->lwp_thread->td_ucred->cr_ruidinfo, 1, 341 (uid != 0) ? p1->p_rlimit[RLIMIT_NPROC].rlim_cur : 0); 342 if (!ok) { 343 /* 344 * Back out the process count 345 */ 346 nprocs--; 347 if (ppsratecheck(&lastfail, &curfail, 1)) 348 kprintf("maxproc limit exceeded by uid %d, please " 349 "see tuning(7) and login.conf(5).\n", uid); 350 tsleep(&forksleep, 0, "fork", hz / 2); 351 error = EAGAIN; 352 goto done; 353 } 354 355 /* Allocate new proc. */ 356 p2 = kmalloc(sizeof(struct proc), M_PROC, M_WAITOK|M_ZERO); 357 358 /* 359 * Setup linkage for kernel based threading XXX lwp 360 */ 361 if (flags & RFTHREAD) { 362 p2->p_peers = p1->p_peers; 363 p1->p_peers = p2; 364 p2->p_leader = p1->p_leader; 365 } else { 366 p2->p_leader = p2; 367 } 368 369 RB_INIT(&p2->p_lwp_tree); 370 spin_init(&p2->p_spin); 371 lwkt_token_init(&p2->p_token, "iproc"); 372 p2->p_lasttid = -1; /* first tid will be 0 */ 373 374 /* 375 * Setting the state to SIDL protects the partially initialized 376 * process once it starts getting hooked into the rest of the system. 377 */ 378 p2->p_stat = SIDL; 379 proc_add_allproc(p2); 380 381 /* 382 * Make a proc table entry for the new process. 383 * The whole structure was zeroed above, so copy the section that is 384 * copied directly from the parent. 385 */ 386 bcopy(&p1->p_startcopy, &p2->p_startcopy, 387 (unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy)); 388 389 /* 390 * Duplicate sub-structures as needed. 391 * Increase reference counts on shared objects. 392 */ 393 if (p1->p_flag & P_PROFIL) 394 startprofclock(p2); 395 p2->p_ucred = crhold(lp1->lwp_thread->td_ucred); 396 KKASSERT(p2->p_lock == 0); 397 398 if (jailed(p2->p_ucred)) 399 p2->p_flag |= P_JAILED; 400 401 if (p2->p_args) 402 p2->p_args->ar_ref++; 403 404 p2->p_usched = p1->p_usched; 405 /* XXX: verify copy of the secondary iosched stuff */ 406 dsched_new_proc(p2); 407 408 if (flags & RFSIGSHARE) { 409 p2->p_sigacts = p1->p_sigacts; 410 p2->p_sigacts->ps_refcnt++; 411 } else { 412 p2->p_sigacts = (struct sigacts *)kmalloc(sizeof(*p2->p_sigacts), 413 M_SUBPROC, M_WAITOK); 414 bcopy(p1->p_sigacts, p2->p_sigacts, sizeof(*p2->p_sigacts)); 415 p2->p_sigacts->ps_refcnt = 1; 416 } 417 if (flags & RFLINUXTHPN) 418 p2->p_sigparent = SIGUSR1; 419 else 420 p2->p_sigparent = SIGCHLD; 421 422 /* bump references to the text vnode (for procfs) */ 423 p2->p_textvp = p1->p_textvp; 424 if (p2->p_textvp) 425 vref(p2->p_textvp); 426 427 /* copy namecache handle to the text file */ 428 if (p1->p_textnch.mount) 429 cache_copy(&p1->p_textnch, &p2->p_textnch); 430 431 /* 432 * Handle file descriptors 433 */ 434 if (flags & RFCFDG) { 435 p2->p_fd = fdinit(p1); 436 fdtol = NULL; 437 } else if (flags & RFFDG) { 438 p2->p_fd = fdcopy(p1); 439 fdtol = NULL; 440 } else { 441 p2->p_fd = fdshare(p1); 442 if (p1->p_fdtol == NULL) 443 p1->p_fdtol = 444 filedesc_to_leader_alloc(NULL, 445 p1->p_leader); 446 if ((flags & RFTHREAD) != 0) { 447 /* 448 * Shared file descriptor table and 449 * shared process leaders. 450 */ 451 fdtol = p1->p_fdtol; 452 fdtol->fdl_refcount++; 453 } else { 454 /* 455 * Shared file descriptor table, and 456 * different process leaders 457 */ 458 fdtol = filedesc_to_leader_alloc(p1->p_fdtol, p2); 459 } 460 } 461 p2->p_fdtol = fdtol; 462 p2->p_limit = plimit_fork(p1); 463 464 /* 465 * Preserve some more flags in subprocess. P_PROFIL has already 466 * been preserved. 467 */ 468 p2->p_flag |= p1->p_flag & P_SUGID; 469 if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT) 470 p2->p_flag |= P_CONTROLT; 471 if (flags & RFPPWAIT) 472 p2->p_flag |= P_PPWAIT; 473 474 /* 475 * Inherit the virtual kernel structure (allows a virtual kernel 476 * to fork to simulate multiple cpus). 477 */ 478 if (p1->p_vkernel) 479 vkernel_inherit(p1, p2); 480 481 /* 482 * Once we are on a pglist we may receive signals. XXX we might 483 * race a ^C being sent to the process group by not receiving it 484 * at all prior to this line. 485 */ 486 LIST_INSERT_AFTER(p1, p2, p_pglist); 487 488 /* 489 * Attach the new process to its parent. 490 * 491 * If RFNOWAIT is set, the newly created process becomes a child 492 * of init. This effectively disassociates the child from the 493 * parent. 494 */ 495 if (flags & RFNOWAIT) 496 pptr = initproc; 497 else 498 pptr = p1; 499 p2->p_pptr = pptr; 500 LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling); 501 LIST_INIT(&p2->p_children); 502 varsymset_init(&p2->p_varsymset, &p1->p_varsymset); 503 callout_init(&p2->p_ithandle); 504 505 #ifdef KTRACE 506 /* 507 * Copy traceflag and tracefile if enabled. If not inherited, 508 * these were zeroed above but we still could have a trace race 509 * so make sure p2's p_tracenode is NULL. 510 */ 511 if ((p1->p_traceflag & KTRFAC_INHERIT) && p2->p_tracenode == NULL) { 512 p2->p_traceflag = p1->p_traceflag; 513 p2->p_tracenode = ktrinherit(p1->p_tracenode); 514 } 515 #endif 516 517 /* 518 * This begins the section where we must prevent the parent 519 * from being swapped. 520 * 521 * Gets PRELE'd in the caller in start_forked_proc(). 522 */ 523 PHOLD(p1); 524 525 vm_fork(p1, p2, flags); 526 527 /* 528 * Create the first lwp associated with the new proc. 529 * It will return via a different execution path later, directly 530 * into userland, after it was put on the runq by 531 * start_forked_proc(). 532 */ 533 lwp_fork(lp1, p2, flags); 534 535 if (flags == (RFFDG | RFPROC | RFPGLOCK)) { 536 mycpu->gd_cnt.v_forks++; 537 mycpu->gd_cnt.v_forkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 538 } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK)) { 539 mycpu->gd_cnt.v_vforks++; 540 mycpu->gd_cnt.v_vforkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 541 } else if (p1 == &proc0) { 542 mycpu->gd_cnt.v_kthreads++; 543 mycpu->gd_cnt.v_kthreadpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 544 } else { 545 mycpu->gd_cnt.v_rforks++; 546 mycpu->gd_cnt.v_rforkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 547 } 548 549 /* 550 * Both processes are set up, now check if any loadable modules want 551 * to adjust anything. 552 * What if they have an error? XXX 553 */ 554 TAILQ_FOREACH(ep, &fork_list, next) { 555 (*ep->function)(p1, p2, flags); 556 } 557 558 /* 559 * Set the start time. Note that the process is not runnable. The 560 * caller is responsible for making it runnable. 561 */ 562 microtime(&p2->p_start); 563 p2->p_acflag = AFORK; 564 565 /* 566 * tell any interested parties about the new process 567 */ 568 KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid); 569 570 /* 571 * Return child proc pointer to parent. 572 */ 573 *procp = p2; 574 done: 575 if (pgrp) 576 lockmgr(&pgrp->pg_lock, LK_RELEASE); 577 return (error); 578 } 579 580 static struct lwp * 581 lwp_fork(struct lwp *origlp, struct proc *destproc, int flags) 582 { 583 struct lwp *lp; 584 struct thread *td; 585 586 lp = kmalloc(sizeof(struct lwp), M_LWP, M_WAITOK|M_ZERO); 587 588 lp->lwp_proc = destproc; 589 lp->lwp_vmspace = destproc->p_vmspace; 590 lp->lwp_stat = LSRUN; 591 bcopy(&origlp->lwp_startcopy, &lp->lwp_startcopy, 592 (unsigned) ((caddr_t)&lp->lwp_endcopy - 593 (caddr_t)&lp->lwp_startcopy)); 594 lp->lwp_flag |= origlp->lwp_flag & LWP_ALTSTACK; 595 /* 596 * Set cpbase to the last timeout that occured (not the upcoming 597 * timeout). 598 * 599 * A critical section is required since a timer IPI can update 600 * scheduler specific data. 601 */ 602 crit_enter(); 603 lp->lwp_cpbase = mycpu->gd_schedclock.time - 604 mycpu->gd_schedclock.periodic; 605 destproc->p_usched->heuristic_forking(origlp, lp); 606 crit_exit(); 607 lp->lwp_cpumask &= usched_mastermask; 608 609 /* 610 * Assign a TID to the lp. Loop until the insert succeeds (returns 611 * NULL). 612 */ 613 lp->lwp_tid = destproc->p_lasttid; 614 do { 615 if (++lp->lwp_tid < 0) 616 lp->lwp_tid = 1; 617 } while (lwp_rb_tree_RB_INSERT(&destproc->p_lwp_tree, lp) != NULL); 618 destproc->p_lasttid = lp->lwp_tid; 619 destproc->p_nthreads++; 620 621 td = lwkt_alloc_thread(NULL, LWKT_THREAD_STACK, -1, 0); 622 lp->lwp_thread = td; 623 td->td_proc = destproc; 624 td->td_lwp = lp; 625 td->td_switch = cpu_heavy_switch; 626 lwkt_setpri(td, TDPRI_KERN_USER); 627 lwkt_set_comm(td, "%s", destproc->p_comm); 628 629 /* 630 * cpu_fork will copy and update the pcb, set up the kernel stack, 631 * and make the child ready to run. 632 */ 633 cpu_fork(origlp, lp, flags); 634 caps_fork(origlp->lwp_thread, lp->lwp_thread); 635 kqueue_init(&lp->lwp_kqueue, destproc->p_fd); 636 637 return (lp); 638 } 639 640 /* 641 * The next two functionms are general routines to handle adding/deleting 642 * items on the fork callout list. 643 * 644 * at_fork(): 645 * Take the arguments given and put them onto the fork callout list, 646 * However first make sure that it's not already there. 647 * Returns 0 on success or a standard error number. 648 */ 649 int 650 at_fork(forklist_fn function) 651 { 652 struct forklist *ep; 653 654 #ifdef INVARIANTS 655 /* let the programmer know if he's been stupid */ 656 if (rm_at_fork(function)) { 657 kprintf("WARNING: fork callout entry (%p) already present\n", 658 function); 659 } 660 #endif 661 ep = kmalloc(sizeof(*ep), M_ATFORK, M_WAITOK|M_ZERO); 662 ep->function = function; 663 TAILQ_INSERT_TAIL(&fork_list, ep, next); 664 return (0); 665 } 666 667 /* 668 * Scan the exit callout list for the given item and remove it.. 669 * Returns the number of items removed (0 or 1) 670 */ 671 int 672 rm_at_fork(forklist_fn function) 673 { 674 struct forklist *ep; 675 676 TAILQ_FOREACH(ep, &fork_list, next) { 677 if (ep->function == function) { 678 TAILQ_REMOVE(&fork_list, ep, next); 679 kfree(ep, M_ATFORK); 680 return(1); 681 } 682 } 683 return (0); 684 } 685 686 /* 687 * Add a forked process to the run queue after any remaining setup, such 688 * as setting the fork handler, has been completed. 689 */ 690 void 691 start_forked_proc(struct lwp *lp1, struct proc *p2) 692 { 693 struct lwp *lp2 = ONLY_LWP_IN_PROC(p2); 694 695 /* 696 * Move from SIDL to RUN queue, and activate the process's thread. 697 * Activation of the thread effectively makes the process "a" 698 * current process, so we do not setrunqueue(). 699 * 700 * YYY setrunqueue works here but we should clean up the trampoline 701 * code so we just schedule the LWKT thread and let the trampoline 702 * deal with the userland scheduler on return to userland. 703 */ 704 KASSERT(p2->p_stat == SIDL, 705 ("cannot start forked process, bad status: %p", p2)); 706 p2->p_usched->resetpriority(lp2); 707 crit_enter(); 708 p2->p_stat = SACTIVE; 709 lp2->lwp_stat = LSRUN; 710 p2->p_usched->setrunqueue(lp2); 711 crit_exit(); 712 713 /* 714 * Now can be swapped. 715 */ 716 PRELE(lp1->lwp_proc); 717 718 /* 719 * Preserve synchronization semantics of vfork. If waiting for 720 * child to exec or exit, set P_PPWAIT on child, and sleep on our 721 * proc (in case of exit). 722 */ 723 while (p2->p_flag & P_PPWAIT) 724 tsleep(lp1->lwp_proc, 0, "ppwait", 0); 725 } 726