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 start_forked_proc(lp, p2); 124 uap->sysmsg_fds[0] = p2->p_pid; 125 uap->sysmsg_fds[1] = 0; 126 } 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 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 return error; 147 } 148 149 /* 150 * Handle rforks. An rfork may (1) operate on the current process without 151 * creating a new, (2) create a new process that shared the current process's 152 * vmspace, signals, and/or descriptors, or (3) create a new process that does 153 * not share these things (normal fork). 154 * 155 * Note that we only call start_forked_proc() if a new process is actually 156 * created. 157 * 158 * rfork { int flags } 159 * 160 * MPALMOSTSAFE 161 */ 162 int 163 sys_rfork(struct rfork_args *uap) 164 { 165 struct lwp *lp = curthread->td_lwp; 166 struct proc *p2; 167 int error; 168 169 if ((uap->flags & RFKERNELONLY) != 0) 170 return (EINVAL); 171 172 error = fork1(lp, uap->flags | RFPGLOCK, &p2); 173 if (error == 0) { 174 if (p2) 175 start_forked_proc(lp, p2); 176 uap->sysmsg_fds[0] = p2 ? p2->p_pid : 0; 177 uap->sysmsg_fds[1] = 0; 178 } 179 return error; 180 } 181 182 /* 183 * MPALMOSTSAFE 184 */ 185 int 186 sys_lwp_create(struct lwp_create_args *uap) 187 { 188 struct proc *p = curproc; 189 struct lwp *lp; 190 struct lwp_params params; 191 int error; 192 193 error = copyin(uap->params, ¶ms, sizeof(params)); 194 if (error) 195 goto fail2; 196 197 lwkt_gettoken(&p->p_token); 198 plimit_lwp_fork(p); /* force exclusive access */ 199 lp = lwp_fork(curthread->td_lwp, p, RFPROC); 200 error = cpu_prepare_lwp(lp, ¶ms); 201 if (error) 202 goto fail; 203 if (params.tid1 != NULL && 204 (error = copyout(&lp->lwp_tid, params.tid1, sizeof(lp->lwp_tid)))) 205 goto fail; 206 if (params.tid2 != NULL && 207 (error = copyout(&lp->lwp_tid, params.tid2, sizeof(lp->lwp_tid)))) 208 goto fail; 209 210 /* 211 * Now schedule the new lwp. 212 */ 213 p->p_usched->resetpriority(lp); 214 crit_enter(); 215 lp->lwp_stat = LSRUN; 216 p->p_usched->setrunqueue(lp); 217 crit_exit(); 218 lwkt_reltoken(&p->p_token); 219 220 return (0); 221 222 fail: 223 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp); 224 --p->p_nthreads; 225 /* lwp_dispose expects an exited lwp, and a held proc */ 226 atomic_set_int(&lp->lwp_mpflags, LWP_MP_WEXIT); 227 lp->lwp_thread->td_flags |= TDF_EXITING; 228 lwkt_remove_tdallq(lp->lwp_thread); 229 PHOLD(p); 230 biosched_done(lp->lwp_thread); 231 dsched_exit_thread(lp->lwp_thread); 232 lwp_dispose(lp); 233 lwkt_reltoken(&p->p_token); 234 fail2: 235 return (error); 236 } 237 238 int nprocs = 1; /* process 0 */ 239 240 int 241 fork1(struct lwp *lp1, int flags, struct proc **procp) 242 { 243 struct proc *p1 = lp1->lwp_proc; 244 struct proc *p2, *pptr; 245 struct pgrp *p1grp; 246 struct pgrp *plkgrp; 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 lwkt_gettoken(&p1->p_token); 258 plkgrp = NULL; 259 260 /* 261 * Here we don't create a new process, but we divorce 262 * certain parts of a process from itself. 263 */ 264 if ((flags & RFPROC) == 0) { 265 /* 266 * This kind of stunt does not work anymore if 267 * there are native threads (lwps) running 268 */ 269 if (p1->p_nthreads != 1) { 270 error = EINVAL; 271 goto done; 272 } 273 274 vm_fork(p1, 0, flags); 275 276 /* 277 * Close all file descriptors. 278 */ 279 if (flags & RFCFDG) { 280 struct filedesc *fdtmp; 281 fdtmp = fdinit(p1); 282 fdfree(p1, fdtmp); 283 } 284 285 /* 286 * Unshare file descriptors (from parent.) 287 */ 288 if (flags & RFFDG) { 289 if (p1->p_fd->fd_refcnt > 1) { 290 struct filedesc *newfd; 291 error = fdcopy(p1, &newfd); 292 if (error != 0) { 293 error = ENOMEM; 294 goto done; 295 } 296 fdfree(p1, newfd); 297 } 298 } 299 *procp = NULL; 300 error = 0; 301 goto done; 302 } 303 304 /* 305 * Interlock against process group signal delivery. If signals 306 * are pending after the interlock is obtained we have to restart 307 * the system call to process the signals. If we don't the child 308 * can miss a pgsignal (such as ^C) sent during the fork. 309 * 310 * We can't use CURSIG() here because it will process any STOPs 311 * and cause the process group lock to be held indefinitely. If 312 * a STOP occurs, the fork will be restarted after the CONT. 313 */ 314 p1grp = p1->p_pgrp; 315 if ((flags & RFPGLOCK) && (plkgrp = p1->p_pgrp) != NULL) { 316 pgref(plkgrp); 317 lockmgr(&plkgrp->pg_lock, LK_SHARED); 318 if (CURSIG_NOBLOCK(lp1)) { 319 error = ERESTART; 320 goto done; 321 } 322 } 323 324 /* 325 * Although process entries are dynamically created, we still keep 326 * a global limit on the maximum number we will create. Don't allow 327 * a nonprivileged user to use the last ten processes; don't let root 328 * exceed the limit. The variable nprocs is the current number of 329 * processes, maxproc is the limit. 330 */ 331 uid = lp1->lwp_thread->td_ucred->cr_ruid; 332 if ((nprocs >= maxproc - 10 && uid != 0) || nprocs >= maxproc) { 333 if (ppsratecheck(&lastfail, &curfail, 1)) 334 kprintf("maxproc limit exceeded by uid %d, please " 335 "see tuning(7) and login.conf(5).\n", uid); 336 tsleep(&forksleep, 0, "fork", hz / 2); 337 error = EAGAIN; 338 goto done; 339 } 340 341 /* 342 * Increment the nprocs resource before blocking can occur. There 343 * are hard-limits as to the number of processes that can run. 344 */ 345 atomic_add_int(&nprocs, 1); 346 347 /* 348 * Increment the count of procs running with this uid. Don't allow 349 * a nonprivileged user to exceed their current limit. 350 */ 351 ok = chgproccnt(lp1->lwp_thread->td_ucred->cr_ruidinfo, 1, 352 (uid != 0) ? p1->p_rlimit[RLIMIT_NPROC].rlim_cur : 0); 353 if (!ok) { 354 /* 355 * Back out the process count 356 */ 357 atomic_add_int(&nprocs, -1); 358 if (ppsratecheck(&lastfail, &curfail, 1)) 359 kprintf("maxproc limit exceeded by uid %d, please " 360 "see tuning(7) and login.conf(5).\n", uid); 361 tsleep(&forksleep, 0, "fork", hz / 2); 362 error = EAGAIN; 363 goto done; 364 } 365 366 /* Allocate new proc. */ 367 p2 = kmalloc(sizeof(struct proc), M_PROC, M_WAITOK|M_ZERO); 368 369 /* 370 * Setup linkage for kernel based threading XXX lwp 371 */ 372 if (flags & RFTHREAD) { 373 p2->p_peers = p1->p_peers; 374 p1->p_peers = p2; 375 p2->p_leader = p1->p_leader; 376 } else { 377 p2->p_leader = p2; 378 } 379 380 RB_INIT(&p2->p_lwp_tree); 381 spin_init(&p2->p_spin); 382 lwkt_token_init(&p2->p_token, "proc"); 383 p2->p_lasttid = -1; /* first tid will be 0 */ 384 385 /* 386 * Setting the state to SIDL protects the partially initialized 387 * process once it starts getting hooked into the rest of the system. 388 */ 389 p2->p_stat = SIDL; 390 proc_add_allproc(p2); 391 392 /* 393 * Make a proc table entry for the new process. 394 * The whole structure was zeroed above, so copy the section that is 395 * copied directly from the parent. 396 */ 397 bcopy(&p1->p_startcopy, &p2->p_startcopy, 398 (unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy)); 399 400 /* 401 * Duplicate sub-structures as needed. Increase reference counts 402 * on shared objects. 403 * 404 * NOTE: because we are now on the allproc list it is possible for 405 * other consumers to gain temporary references to p2 406 * (p2->p_lock can change). 407 */ 408 if (p1->p_flags & P_PROFIL) 409 startprofclock(p2); 410 p2->p_ucred = crhold(lp1->lwp_thread->td_ucred); 411 412 if (jailed(p2->p_ucred)) 413 p2->p_flags |= P_JAILED; 414 415 if (p2->p_args) 416 refcount_acquire(&p2->p_args->ar_ref); 417 418 p2->p_usched = p1->p_usched; 419 /* XXX: verify copy of the secondary iosched stuff */ 420 dsched_new_proc(p2); 421 422 if (flags & RFSIGSHARE) { 423 p2->p_sigacts = p1->p_sigacts; 424 refcount_acquire(&p2->p_sigacts->ps_refcnt); 425 } else { 426 p2->p_sigacts = kmalloc(sizeof(*p2->p_sigacts), 427 M_SUBPROC, M_WAITOK); 428 bcopy(p1->p_sigacts, p2->p_sigacts, sizeof(*p2->p_sigacts)); 429 refcount_init(&p2->p_sigacts->ps_refcnt, 1); 430 } 431 if (flags & RFLINUXTHPN) 432 p2->p_sigparent = SIGUSR1; 433 else 434 p2->p_sigparent = SIGCHLD; 435 436 /* bump references to the text vnode (for procfs) */ 437 p2->p_textvp = p1->p_textvp; 438 if (p2->p_textvp) 439 vref(p2->p_textvp); 440 441 /* copy namecache handle to the text file */ 442 if (p1->p_textnch.mount) 443 cache_copy(&p1->p_textnch, &p2->p_textnch); 444 445 /* 446 * Handle file descriptors 447 */ 448 if (flags & RFCFDG) { 449 p2->p_fd = fdinit(p1); 450 fdtol = NULL; 451 } else if (flags & RFFDG) { 452 error = fdcopy(p1, &p2->p_fd); 453 if (error != 0) { 454 error = ENOMEM; 455 goto done; 456 } 457 fdtol = NULL; 458 } else { 459 p2->p_fd = fdshare(p1); 460 if (p1->p_fdtol == NULL) { 461 lwkt_gettoken(&p1->p_token); 462 p1->p_fdtol = 463 filedesc_to_leader_alloc(NULL, 464 p1->p_leader); 465 lwkt_reltoken(&p1->p_token); 466 } 467 if ((flags & RFTHREAD) != 0) { 468 /* 469 * Shared file descriptor table and 470 * shared process leaders. 471 */ 472 fdtol = p1->p_fdtol; 473 fdtol->fdl_refcount++; 474 } else { 475 /* 476 * Shared file descriptor table, and 477 * different process leaders 478 */ 479 fdtol = filedesc_to_leader_alloc(p1->p_fdtol, p2); 480 } 481 } 482 p2->p_fdtol = fdtol; 483 p2->p_limit = plimit_fork(p1); 484 485 /* 486 * Preserve some more flags in subprocess. P_PROFIL has already 487 * been preserved. 488 */ 489 p2->p_flags |= p1->p_flags & P_SUGID; 490 if (p1->p_session->s_ttyvp != NULL && p1->p_flags & P_CONTROLT) 491 p2->p_flags |= P_CONTROLT; 492 if (flags & RFPPWAIT) 493 p2->p_flags |= P_PPWAIT; 494 495 /* 496 * Inherit the virtual kernel structure (allows a virtual kernel 497 * to fork to simulate multiple cpus). 498 */ 499 if (p1->p_vkernel) 500 vkernel_inherit(p1, p2); 501 502 /* 503 * Once we are on a pglist we may receive signals. XXX we might 504 * race a ^C being sent to the process group by not receiving it 505 * at all prior to this line. 506 */ 507 pgref(p1grp); 508 lwkt_gettoken(&p1grp->pg_token); 509 LIST_INSERT_AFTER(p1, p2, p_pglist); 510 lwkt_reltoken(&p1grp->pg_token); 511 512 /* 513 * Attach the new process to its parent. 514 * 515 * If RFNOWAIT is set, the newly created process becomes a child 516 * of init. This effectively disassociates the child from the 517 * parent. 518 */ 519 if (flags & RFNOWAIT) 520 pptr = initproc; 521 else 522 pptr = p1; 523 p2->p_pptr = pptr; 524 LIST_INIT(&p2->p_children); 525 526 lwkt_gettoken(&pptr->p_token); 527 LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling); 528 lwkt_reltoken(&pptr->p_token); 529 530 varsymset_init(&p2->p_varsymset, &p1->p_varsymset); 531 callout_init_mp(&p2->p_ithandle); 532 533 #ifdef KTRACE 534 /* 535 * Copy traceflag and tracefile if enabled. If not inherited, 536 * these were zeroed above but we still could have a trace race 537 * so make sure p2's p_tracenode is NULL. 538 */ 539 if ((p1->p_traceflag & KTRFAC_INHERIT) && p2->p_tracenode == NULL) { 540 p2->p_traceflag = p1->p_traceflag; 541 p2->p_tracenode = ktrinherit(p1->p_tracenode); 542 } 543 #endif 544 545 /* 546 * This begins the section where we must prevent the parent 547 * from being swapped. 548 * 549 * Gets PRELE'd in the caller in start_forked_proc(). 550 */ 551 PHOLD(p1); 552 553 vm_fork(p1, p2, flags); 554 555 /* 556 * Create the first lwp associated with the new proc. 557 * It will return via a different execution path later, directly 558 * into userland, after it was put on the runq by 559 * start_forked_proc(). 560 */ 561 lwp_fork(lp1, p2, flags); 562 563 if (flags == (RFFDG | RFPROC | RFPGLOCK)) { 564 mycpu->gd_cnt.v_forks++; 565 mycpu->gd_cnt.v_forkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 566 } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK)) { 567 mycpu->gd_cnt.v_vforks++; 568 mycpu->gd_cnt.v_vforkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 569 } else if (p1 == &proc0) { 570 mycpu->gd_cnt.v_kthreads++; 571 mycpu->gd_cnt.v_kthreadpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 572 } else { 573 mycpu->gd_cnt.v_rforks++; 574 mycpu->gd_cnt.v_rforkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; 575 } 576 577 /* 578 * Both processes are set up, now check if any loadable modules want 579 * to adjust anything. 580 * What if they have an error? XXX 581 */ 582 TAILQ_FOREACH(ep, &fork_list, next) { 583 (*ep->function)(p1, p2, flags); 584 } 585 586 /* 587 * Set the start time. Note that the process is not runnable. The 588 * caller is responsible for making it runnable. 589 */ 590 microtime(&p2->p_start); 591 p2->p_acflag = AFORK; 592 593 /* 594 * tell any interested parties about the new process 595 */ 596 KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid); 597 598 /* 599 * Return child proc pointer to parent. 600 */ 601 *procp = p2; 602 error = 0; 603 done: 604 lwkt_reltoken(&p1->p_token); 605 if (plkgrp) { 606 lockmgr(&plkgrp->pg_lock, LK_RELEASE); 607 pgrel(plkgrp); 608 } 609 return (error); 610 } 611 612 static struct lwp * 613 lwp_fork(struct lwp *origlp, struct proc *destproc, int flags) 614 { 615 globaldata_t gd = mycpu; 616 struct lwp *lp; 617 struct thread *td; 618 619 lp = kmalloc(sizeof(struct lwp), M_LWP, M_WAITOK|M_ZERO); 620 621 lp->lwp_proc = destproc; 622 lp->lwp_vmspace = destproc->p_vmspace; 623 lp->lwp_stat = LSRUN; 624 bcopy(&origlp->lwp_startcopy, &lp->lwp_startcopy, 625 (unsigned) ((caddr_t)&lp->lwp_endcopy - 626 (caddr_t)&lp->lwp_startcopy)); 627 lp->lwp_flags |= origlp->lwp_flags & LWP_ALTSTACK; 628 /* 629 * Set cpbase to the last timeout that occured (not the upcoming 630 * timeout). 631 * 632 * A critical section is required since a timer IPI can update 633 * scheduler specific data. 634 */ 635 crit_enter(); 636 lp->lwp_cpbase = gd->gd_schedclock.time - gd->gd_schedclock.periodic; 637 destproc->p_usched->heuristic_forking(origlp, lp); 638 crit_exit(); 639 lp->lwp_cpumask &= usched_mastermask; 640 lwkt_token_init(&lp->lwp_token, "lwp_token"); 641 spin_init(&lp->lwp_spin); 642 643 /* 644 * Assign the thread to the current cpu to begin with so we 645 * can manipulate it. 646 */ 647 td = lwkt_alloc_thread(NULL, LWKT_THREAD_STACK, gd->gd_cpuid, 0); 648 lp->lwp_thread = td; 649 td->td_proc = destproc; 650 td->td_lwp = lp; 651 td->td_switch = cpu_heavy_switch; 652 lwkt_setpri(td, TDPRI_KERN_USER); 653 lwkt_set_comm(td, "%s", destproc->p_comm); 654 655 /* 656 * cpu_fork will copy and update the pcb, set up the kernel stack, 657 * and make the child ready to run. 658 */ 659 cpu_fork(origlp, lp, flags); 660 caps_fork(origlp->lwp_thread, lp->lwp_thread); 661 kqueue_init(&lp->lwp_kqueue, destproc->p_fd); 662 663 /* 664 * Assign a TID to the lp. Loop until the insert succeeds (returns 665 * NULL). 666 */ 667 lp->lwp_tid = destproc->p_lasttid; 668 do { 669 if (++lp->lwp_tid < 0) 670 lp->lwp_tid = 1; 671 } while (lwp_rb_tree_RB_INSERT(&destproc->p_lwp_tree, lp) != NULL); 672 destproc->p_lasttid = lp->lwp_tid; 673 destproc->p_nthreads++; 674 675 return (lp); 676 } 677 678 /* 679 * The next two functionms are general routines to handle adding/deleting 680 * items on the fork callout list. 681 * 682 * at_fork(): 683 * Take the arguments given and put them onto the fork callout list, 684 * However first make sure that it's not already there. 685 * Returns 0 on success or a standard error number. 686 */ 687 int 688 at_fork(forklist_fn function) 689 { 690 struct forklist *ep; 691 692 #ifdef INVARIANTS 693 /* let the programmer know if he's been stupid */ 694 if (rm_at_fork(function)) { 695 kprintf("WARNING: fork callout entry (%p) already present\n", 696 function); 697 } 698 #endif 699 ep = kmalloc(sizeof(*ep), M_ATFORK, M_WAITOK|M_ZERO); 700 ep->function = function; 701 TAILQ_INSERT_TAIL(&fork_list, ep, next); 702 return (0); 703 } 704 705 /* 706 * Scan the exit callout list for the given item and remove it.. 707 * Returns the number of items removed (0 or 1) 708 */ 709 int 710 rm_at_fork(forklist_fn function) 711 { 712 struct forklist *ep; 713 714 TAILQ_FOREACH(ep, &fork_list, next) { 715 if (ep->function == function) { 716 TAILQ_REMOVE(&fork_list, ep, next); 717 kfree(ep, M_ATFORK); 718 return(1); 719 } 720 } 721 return (0); 722 } 723 724 /* 725 * Add a forked process to the run queue after any remaining setup, such 726 * as setting the fork handler, has been completed. 727 */ 728 void 729 start_forked_proc(struct lwp *lp1, struct proc *p2) 730 { 731 struct lwp *lp2 = ONLY_LWP_IN_PROC(p2); 732 733 /* 734 * Move from SIDL to RUN queue, and activate the process's thread. 735 * Activation of the thread effectively makes the process "a" 736 * current process, so we do not setrunqueue(). 737 * 738 * YYY setrunqueue works here but we should clean up the trampoline 739 * code so we just schedule the LWKT thread and let the trampoline 740 * deal with the userland scheduler on return to userland. 741 */ 742 KASSERT(p2->p_stat == SIDL, 743 ("cannot start forked process, bad status: %p", p2)); 744 p2->p_usched->resetpriority(lp2); 745 crit_enter(); 746 p2->p_stat = SACTIVE; 747 lp2->lwp_stat = LSRUN; 748 p2->p_usched->setrunqueue(lp2); 749 crit_exit(); 750 751 /* 752 * Now can be swapped. 753 */ 754 PRELE(lp1->lwp_proc); 755 756 /* 757 * Preserve synchronization semantics of vfork. If waiting for 758 * child to exec or exit, set P_PPWAIT on child, and sleep on our 759 * proc (in case of exec or exit). 760 * 761 * We must hold our p_token to interlock the flag/tsleep 762 */ 763 lwkt_gettoken(&p2->p_token); 764 while (p2->p_flags & P_PPWAIT) 765 tsleep(lp1->lwp_proc, 0, "ppwait", 0); 766 lwkt_reltoken(&p2->p_token); 767 } 768