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/refcount.h> 69 #include <sys/thread2.h> 70 #include <sys/signal2.h> 71 #include <sys/spinlock2.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 error = fork1(lp, RFFDG | RFPROC | RFPGLOCK, &p2); 122 if (error == 0) { 123 PHOLD(p2); 124 start_forked_proc(lp, p2); 125 uap->sysmsg_fds[0] = p2->p_pid; 126 uap->sysmsg_fds[1] = 0; 127 PRELE(p2); 128 } 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 error = fork1(lp, RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK, &p2); 143 if (error == 0) { 144 PHOLD(p2); 145 start_forked_proc(lp, p2); 146 uap->sysmsg_fds[0] = p2->p_pid; 147 uap->sysmsg_fds[1] = 0; 148 PRELE(p2); 149 } 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 error = fork1(lp, uap->flags | RFPGLOCK, &p2); 177 if (error == 0) { 178 if (p2) { 179 PHOLD(p2); 180 start_forked_proc(lp, p2); 181 uap->sysmsg_fds[0] = p2->p_pid; 182 uap->sysmsg_fds[1] = 0; 183 PRELE(p2); 184 } else { 185 uap->sysmsg_fds[0] = 0; 186 uap->sysmsg_fds[1] = 0; 187 } 188 } 189 return error; 190 } 191 192 /* 193 * MPALMOSTSAFE 194 */ 195 int 196 sys_lwp_create(struct lwp_create_args *uap) 197 { 198 struct proc *p = curproc; 199 struct lwp *lp; 200 struct lwp_params params; 201 int error; 202 203 error = copyin(uap->params, ¶ms, sizeof(params)); 204 if (error) 205 goto fail2; 206 207 lwkt_gettoken(&p->p_token); 208 plimit_lwp_fork(p); /* force exclusive access */ 209 lp = lwp_fork(curthread->td_lwp, p, RFPROC); 210 error = cpu_prepare_lwp(lp, ¶ms); 211 if (error) 212 goto fail; 213 if (params.tid1 != NULL && 214 (error = copyout(&lp->lwp_tid, params.tid1, sizeof(lp->lwp_tid)))) 215 goto fail; 216 if (params.tid2 != NULL && 217 (error = copyout(&lp->lwp_tid, params.tid2, sizeof(lp->lwp_tid)))) 218 goto fail; 219 220 /* 221 * Now schedule the new lwp. 222 */ 223 p->p_usched->resetpriority(lp); 224 crit_enter(); 225 lp->lwp_stat = LSRUN; 226 p->p_usched->setrunqueue(lp); 227 crit_exit(); 228 lwkt_reltoken(&p->p_token); 229 230 return (0); 231 232 fail: 233 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp); 234 --p->p_nthreads; 235 /* lwp_dispose expects an exited lwp, and a held proc */ 236 atomic_set_int(&lp->lwp_mpflags, LWP_MP_WEXIT); 237 lp->lwp_thread->td_flags |= TDF_EXITING; 238 lwkt_remove_tdallq(lp->lwp_thread); 239 PHOLD(p); 240 biosched_done(lp->lwp_thread); 241 dsched_exit_thread(lp->lwp_thread); 242 lwp_dispose(lp); 243 lwkt_reltoken(&p->p_token); 244 fail2: 245 return (error); 246 } 247 248 int nprocs = 1; /* process 0 */ 249 250 int 251 fork1(struct lwp *lp1, int flags, struct proc **procp) 252 { 253 struct proc *p1 = lp1->lwp_proc; 254 struct proc *p2; 255 struct proc *pptr; 256 struct pgrp *p1grp; 257 struct pgrp *plkgrp; 258 uid_t uid; 259 int ok, error; 260 static int curfail = 0; 261 static struct timeval lastfail; 262 struct forklist *ep; 263 struct filedesc_to_leader *fdtol; 264 265 if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG)) 266 return (EINVAL); 267 268 lwkt_gettoken(&p1->p_token); 269 plkgrp = NULL; 270 p2 = NULL; 271 272 /* 273 * Here we don't create a new process, but we divorce 274 * certain parts of a process from itself. 275 */ 276 if ((flags & RFPROC) == 0) { 277 /* 278 * This kind of stunt does not work anymore if 279 * there are native threads (lwps) running 280 */ 281 if (p1->p_nthreads != 1) { 282 error = EINVAL; 283 goto done; 284 } 285 286 vm_fork(p1, 0, flags); 287 288 /* 289 * Close all file descriptors. 290 */ 291 if (flags & RFCFDG) { 292 struct filedesc *fdtmp; 293 fdtmp = fdinit(p1); 294 fdfree(p1, fdtmp); 295 } 296 297 /* 298 * Unshare file descriptors (from parent.) 299 */ 300 if (flags & RFFDG) { 301 if (p1->p_fd->fd_refcnt > 1) { 302 struct filedesc *newfd; 303 error = fdcopy(p1, &newfd); 304 if (error != 0) { 305 error = ENOMEM; 306 goto done; 307 } 308 fdfree(p1, newfd); 309 } 310 } 311 *procp = NULL; 312 error = 0; 313 goto done; 314 } 315 316 /* 317 * Interlock against process group signal delivery. If signals 318 * are pending after the interlock is obtained we have to restart 319 * the system call to process the signals. If we don't the child 320 * can miss a pgsignal (such as ^C) sent during the fork. 321 * 322 * We can't use CURSIG() here because it will process any STOPs 323 * and cause the process group lock to be held indefinitely. If 324 * a STOP occurs, the fork will be restarted after the CONT. 325 */ 326 p1grp = p1->p_pgrp; 327 if ((flags & RFPGLOCK) && (plkgrp = p1->p_pgrp) != NULL) { 328 pgref(plkgrp); 329 lockmgr(&plkgrp->pg_lock, LK_SHARED); 330 if (CURSIG_NOBLOCK(lp1)) { 331 error = ERESTART; 332 goto done; 333 } 334 } 335 336 /* 337 * Although process entries are dynamically created, we still keep 338 * a global limit on the maximum number we will create. Don't allow 339 * a nonprivileged user to use the last ten processes; don't let root 340 * exceed the limit. The variable nprocs is the current number of 341 * processes, maxproc is the limit. 342 */ 343 uid = lp1->lwp_thread->td_ucred->cr_ruid; 344 if ((nprocs >= maxproc - 10 && uid != 0) || nprocs >= maxproc) { 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 /* 354 * Increment the nprocs resource before blocking can occur. There 355 * are hard-limits as to the number of processes that can run. 356 */ 357 atomic_add_int(&nprocs, 1); 358 359 /* 360 * Increment the count of procs running with this uid. Don't allow 361 * a nonprivileged user to exceed their current limit. 362 */ 363 ok = chgproccnt(lp1->lwp_thread->td_ucred->cr_ruidinfo, 1, 364 (uid != 0) ? p1->p_rlimit[RLIMIT_NPROC].rlim_cur : 0); 365 if (!ok) { 366 /* 367 * Back out the process count 368 */ 369 atomic_add_int(&nprocs, -1); 370 if (ppsratecheck(&lastfail, &curfail, 1)) 371 kprintf("maxproc limit exceeded by uid %d, please " 372 "see tuning(7) and login.conf(5).\n", uid); 373 tsleep(&forksleep, 0, "fork", hz / 2); 374 error = EAGAIN; 375 goto done; 376 } 377 378 /* 379 * Allocate a new process, don't get fancy: zero the structure. 380 */ 381 p2 = kmalloc(sizeof(struct proc), M_PROC, M_WAITOK|M_ZERO); 382 383 /* 384 * Core initialization. SIDL is a safety state that protects the 385 * partially initialized process once it starts getting hooked 386 * into system structures and becomes addressable. 387 * 388 * We must be sure to acquire p2->p_token as well, we must hold it 389 * once the process is on the allproc list to avoid things such 390 * as competing modifications to p_flags. 391 */ 392 p2->p_lasttid = -1; /* first tid will be 0 */ 393 p2->p_stat = SIDL; 394 395 RB_INIT(&p2->p_lwp_tree); 396 spin_init(&p2->p_spin); 397 lwkt_token_init(&p2->p_token, "proc"); 398 lwkt_gettoken(&p2->p_token); 399 400 /* 401 * Setup linkage for kernel based threading XXX lwp. Also add the 402 * process to the allproclist. 403 * 404 * The process structure is addressable after this point. 405 */ 406 if (flags & RFTHREAD) { 407 p2->p_peers = p1->p_peers; 408 p1->p_peers = p2; 409 p2->p_leader = p1->p_leader; 410 } else { 411 p2->p_leader = p2; 412 } 413 proc_add_allproc(p2); 414 415 /* 416 * Initialize the section which is copied verbatim from the parent. 417 */ 418 bcopy(&p1->p_startcopy, &p2->p_startcopy, 419 ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy)); 420 421 /* 422 * Duplicate sub-structures as needed. Increase reference counts 423 * on shared objects. 424 * 425 * NOTE: because we are now on the allproc list it is possible for 426 * other consumers to gain temporary references to p2 427 * (p2->p_lock can change). 428 */ 429 if (p1->p_flags & P_PROFIL) 430 startprofclock(p2); 431 p2->p_ucred = crhold(lp1->lwp_thread->td_ucred); 432 433 if (jailed(p2->p_ucred)) 434 p2->p_flags |= P_JAILED; 435 436 if (p2->p_args) 437 refcount_acquire(&p2->p_args->ar_ref); 438 439 p2->p_usched = p1->p_usched; 440 /* XXX: verify copy of the secondary iosched stuff */ 441 dsched_new_proc(p2); 442 443 if (flags & RFSIGSHARE) { 444 p2->p_sigacts = p1->p_sigacts; 445 refcount_acquire(&p2->p_sigacts->ps_refcnt); 446 } else { 447 p2->p_sigacts = kmalloc(sizeof(*p2->p_sigacts), 448 M_SUBPROC, M_WAITOK); 449 bcopy(p1->p_sigacts, p2->p_sigacts, sizeof(*p2->p_sigacts)); 450 refcount_init(&p2->p_sigacts->ps_refcnt, 1); 451 } 452 if (flags & RFLINUXTHPN) 453 p2->p_sigparent = SIGUSR1; 454 else 455 p2->p_sigparent = SIGCHLD; 456 457 /* bump references to the text vnode (for procfs) */ 458 p2->p_textvp = p1->p_textvp; 459 if (p2->p_textvp) 460 vref(p2->p_textvp); 461 462 /* copy namecache handle to the text file */ 463 if (p1->p_textnch.mount) 464 cache_copy(&p1->p_textnch, &p2->p_textnch); 465 466 /* 467 * Handle file descriptors 468 */ 469 if (flags & RFCFDG) { 470 p2->p_fd = fdinit(p1); 471 fdtol = NULL; 472 } else if (flags & RFFDG) { 473 error = fdcopy(p1, &p2->p_fd); 474 if (error != 0) { 475 error = ENOMEM; 476 goto done; 477 } 478 fdtol = NULL; 479 } else { 480 p2->p_fd = fdshare(p1); 481 if (p1->p_fdtol == NULL) { 482 p1->p_fdtol = filedesc_to_leader_alloc(NULL, 483 p1->p_leader); 484 } 485 if ((flags & RFTHREAD) != 0) { 486 /* 487 * Shared file descriptor table and 488 * shared process leaders. 489 */ 490 fdtol = p1->p_fdtol; 491 fdtol->fdl_refcount++; 492 } else { 493 /* 494 * Shared file descriptor table, and 495 * different process leaders 496 */ 497 fdtol = filedesc_to_leader_alloc(p1->p_fdtol, p2); 498 } 499 } 500 p2->p_fdtol = fdtol; 501 p2->p_limit = plimit_fork(p1); 502 503 /* 504 * Preserve some more flags in subprocess. P_PROFIL has already 505 * been preserved. 506 */ 507 p2->p_flags |= p1->p_flags & P_SUGID; 508 if (p1->p_session->s_ttyvp != NULL && (p1->p_flags & P_CONTROLT)) 509 p2->p_flags |= P_CONTROLT; 510 if (flags & RFPPWAIT) 511 p2->p_flags |= P_PPWAIT; 512 513 /* 514 * Inherit the virtual kernel structure (allows a virtual kernel 515 * to fork to simulate multiple cpus). 516 */ 517 if (p1->p_vkernel) 518 vkernel_inherit(p1, p2); 519 520 /* 521 * Once we are on a pglist we may receive signals. XXX we might 522 * race a ^C being sent to the process group by not receiving it 523 * at all prior to this line. 524 */ 525 pgref(p1grp); 526 lwkt_gettoken(&p1grp->pg_token); 527 LIST_INSERT_AFTER(p1, p2, p_pglist); 528 lwkt_reltoken(&p1grp->pg_token); 529 530 /* 531 * Attach the new process to its parent. 532 * 533 * If RFNOWAIT is set, the newly created process becomes a child 534 * of init. This effectively disassociates the child from the 535 * parent. 536 */ 537 if (flags & RFNOWAIT) 538 pptr = initproc; 539 else 540 pptr = p1; 541 p2->p_pptr = pptr; 542 LIST_INIT(&p2->p_children); 543 544 lwkt_gettoken(&pptr->p_token); 545 LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling); 546 lwkt_reltoken(&pptr->p_token); 547 548 varsymset_init(&p2->p_varsymset, &p1->p_varsymset); 549 callout_init_mp(&p2->p_ithandle); 550 551 #ifdef KTRACE 552 /* 553 * Copy traceflag and tracefile if enabled. If not inherited, 554 * these were zeroed above but we still could have a trace race 555 * so make sure p2's p_tracenode is NULL. 556 */ 557 if ((p1->p_traceflag & KTRFAC_INHERIT) && p2->p_tracenode == NULL) { 558 p2->p_traceflag = p1->p_traceflag; 559 p2->p_tracenode = ktrinherit(p1->p_tracenode); 560 } 561 #endif 562 563 /* 564 * This begins the section where we must prevent the parent 565 * from being swapped. 566 * 567 * Gets PRELE'd in the caller in start_forked_proc(). 568 */ 569 PHOLD(p1); 570 571 vm_fork(p1, p2, flags); 572 573 /* 574 * Create the first lwp associated with the new proc. 575 * It will return via a different execution path later, directly 576 * into userland, after it was put on the runq by 577 * start_forked_proc(). 578 */ 579 lwp_fork(lp1, p2, flags); 580 581 if (flags == (RFFDG | RFPROC | RFPGLOCK)) { 582 mycpu->gd_cnt.v_forks++; 583 mycpu->gd_cnt.v_forkpages += p2->p_vmspace->vm_dsize + 584 p2->p_vmspace->vm_ssize; 585 } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK)) { 586 mycpu->gd_cnt.v_vforks++; 587 mycpu->gd_cnt.v_vforkpages += p2->p_vmspace->vm_dsize + 588 p2->p_vmspace->vm_ssize; 589 } else if (p1 == &proc0) { 590 mycpu->gd_cnt.v_kthreads++; 591 mycpu->gd_cnt.v_kthreadpages += p2->p_vmspace->vm_dsize + 592 p2->p_vmspace->vm_ssize; 593 } else { 594 mycpu->gd_cnt.v_rforks++; 595 mycpu->gd_cnt.v_rforkpages += p2->p_vmspace->vm_dsize + 596 p2->p_vmspace->vm_ssize; 597 } 598 599 /* 600 * Both processes are set up, now check if any loadable modules want 601 * to adjust anything. 602 * What if they have an error? XXX 603 */ 604 TAILQ_FOREACH(ep, &fork_list, next) { 605 (*ep->function)(p1, p2, flags); 606 } 607 608 /* 609 * Set the start time. Note that the process is not runnable. The 610 * caller is responsible for making it runnable. 611 */ 612 microtime(&p2->p_start); 613 p2->p_acflag = AFORK; 614 615 /* 616 * tell any interested parties about the new process 617 */ 618 KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid); 619 620 /* 621 * Return child proc pointer to parent. 622 */ 623 *procp = p2; 624 error = 0; 625 done: 626 if (p2) 627 lwkt_reltoken(&p2->p_token); 628 lwkt_reltoken(&p1->p_token); 629 if (plkgrp) { 630 lockmgr(&plkgrp->pg_lock, LK_RELEASE); 631 pgrel(plkgrp); 632 } 633 return (error); 634 } 635 636 static struct lwp * 637 lwp_fork(struct lwp *origlp, struct proc *destproc, int flags) 638 { 639 globaldata_t gd = mycpu; 640 struct lwp *lp; 641 struct thread *td; 642 643 lp = kmalloc(sizeof(struct lwp), M_LWP, M_WAITOK|M_ZERO); 644 645 lp->lwp_proc = destproc; 646 lp->lwp_vmspace = destproc->p_vmspace; 647 lp->lwp_stat = LSRUN; 648 bcopy(&origlp->lwp_startcopy, &lp->lwp_startcopy, 649 (unsigned) ((caddr_t)&lp->lwp_endcopy - 650 (caddr_t)&lp->lwp_startcopy)); 651 lp->lwp_flags |= origlp->lwp_flags & LWP_ALTSTACK; 652 /* 653 * Set cpbase to the last timeout that occured (not the upcoming 654 * timeout). 655 * 656 * A critical section is required since a timer IPI can update 657 * scheduler specific data. 658 */ 659 crit_enter(); 660 lp->lwp_cpbase = gd->gd_schedclock.time - gd->gd_schedclock.periodic; 661 destproc->p_usched->heuristic_forking(origlp, lp); 662 crit_exit(); 663 lp->lwp_cpumask &= usched_mastermask; 664 lwkt_token_init(&lp->lwp_token, "lwp_token"); 665 spin_init(&lp->lwp_spin); 666 667 /* 668 * Assign the thread to the current cpu to begin with so we 669 * can manipulate it. 670 */ 671 td = lwkt_alloc_thread(NULL, LWKT_THREAD_STACK, gd->gd_cpuid, 0); 672 lp->lwp_thread = td; 673 td->td_proc = destproc; 674 td->td_lwp = lp; 675 td->td_switch = cpu_heavy_switch; 676 lwkt_setpri(td, TDPRI_KERN_USER); 677 lwkt_set_comm(td, "%s", destproc->p_comm); 678 679 /* 680 * cpu_fork will copy and update the pcb, set up the kernel stack, 681 * and make the child ready to run. 682 */ 683 cpu_fork(origlp, lp, flags); 684 caps_fork(origlp->lwp_thread, lp->lwp_thread); 685 kqueue_init(&lp->lwp_kqueue, destproc->p_fd); 686 687 /* 688 * Assign a TID to the lp. Loop until the insert succeeds (returns 689 * NULL). 690 */ 691 lp->lwp_tid = destproc->p_lasttid; 692 do { 693 if (++lp->lwp_tid < 0) 694 lp->lwp_tid = 1; 695 } while (lwp_rb_tree_RB_INSERT(&destproc->p_lwp_tree, lp) != NULL); 696 destproc->p_lasttid = lp->lwp_tid; 697 destproc->p_nthreads++; 698 699 return (lp); 700 } 701 702 /* 703 * The next two functionms are general routines to handle adding/deleting 704 * items on the fork callout list. 705 * 706 * at_fork(): 707 * Take the arguments given and put them onto the fork callout list, 708 * However first make sure that it's not already there. 709 * Returns 0 on success or a standard error number. 710 */ 711 int 712 at_fork(forklist_fn function) 713 { 714 struct forklist *ep; 715 716 #ifdef INVARIANTS 717 /* let the programmer know if he's been stupid */ 718 if (rm_at_fork(function)) { 719 kprintf("WARNING: fork callout entry (%p) already present\n", 720 function); 721 } 722 #endif 723 ep = kmalloc(sizeof(*ep), M_ATFORK, M_WAITOK|M_ZERO); 724 ep->function = function; 725 TAILQ_INSERT_TAIL(&fork_list, ep, next); 726 return (0); 727 } 728 729 /* 730 * Scan the exit callout list for the given item and remove it.. 731 * Returns the number of items removed (0 or 1) 732 */ 733 int 734 rm_at_fork(forklist_fn function) 735 { 736 struct forklist *ep; 737 738 TAILQ_FOREACH(ep, &fork_list, next) { 739 if (ep->function == function) { 740 TAILQ_REMOVE(&fork_list, ep, next); 741 kfree(ep, M_ATFORK); 742 return(1); 743 } 744 } 745 return (0); 746 } 747 748 /* 749 * Add a forked process to the run queue after any remaining setup, such 750 * as setting the fork handler, has been completed. 751 * 752 * p2 is held by the caller. 753 */ 754 void 755 start_forked_proc(struct lwp *lp1, struct proc *p2) 756 { 757 struct lwp *lp2 = ONLY_LWP_IN_PROC(p2); 758 759 /* 760 * Move from SIDL to RUN queue, and activate the process's thread. 761 * Activation of the thread effectively makes the process "a" 762 * current process, so we do not setrunqueue(). 763 * 764 * YYY setrunqueue works here but we should clean up the trampoline 765 * code so we just schedule the LWKT thread and let the trampoline 766 * deal with the userland scheduler on return to userland. 767 */ 768 KASSERT(p2->p_stat == SIDL, 769 ("cannot start forked process, bad status: %p", p2)); 770 p2->p_usched->resetpriority(lp2); 771 crit_enter(); 772 p2->p_stat = SACTIVE; 773 lp2->lwp_stat = LSRUN; 774 p2->p_usched->setrunqueue(lp2); 775 crit_exit(); 776 777 /* 778 * Now can be swapped. 779 */ 780 PRELE(lp1->lwp_proc); 781 782 /* 783 * Preserve synchronization semantics of vfork. If waiting for 784 * child to exec or exit, set P_PPWAIT on child, and sleep on our 785 * proc (in case of exec or exit). 786 * 787 * We must hold our p_token to interlock the flag/tsleep 788 */ 789 lwkt_gettoken(&p2->p_token); 790 while (p2->p_flags & P_PPWAIT) 791 tsleep(lp1->lwp_proc, 0, "ppwait", 0); 792 lwkt_reltoken(&p2->p_token); 793 } 794