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 * $FreeBSD$ 40 */ 41 42 #include "opt_ktrace.h" 43 #include "opt_mac.h" 44 45 #include <sys/param.h> 46 #include <sys/systm.h> 47 #include <sys/sysproto.h> 48 #include <sys/eventhandler.h> 49 #include <sys/filedesc.h> 50 #include <sys/kernel.h> 51 #include <sys/sysctl.h> 52 #include <sys/lock.h> 53 #include <sys/malloc.h> 54 #include <sys/mutex.h> 55 #include <sys/proc.h> 56 #include <sys/pioctl.h> 57 #include <sys/resourcevar.h> 58 #include <sys/sched.h> 59 #include <sys/syscall.h> 60 #include <sys/vnode.h> 61 #include <sys/acct.h> 62 #include <sys/mac.h> 63 #include <sys/ktr.h> 64 #include <sys/ktrace.h> 65 #include <sys/kthread.h> 66 #include <sys/unistd.h> 67 #include <sys/jail.h> 68 #include <sys/sx.h> 69 70 #include <vm/vm.h> 71 #include <vm/pmap.h> 72 #include <vm/vm_map.h> 73 #include <vm/vm_extern.h> 74 #include <vm/uma.h> 75 76 #include <sys/vmmeter.h> 77 #include <sys/user.h> 78 #include <machine/critical.h> 79 80 #ifndef _SYS_SYSPROTO_H_ 81 struct fork_args { 82 int dummy; 83 }; 84 #endif 85 86 int forksleep; /* Place for fork1() to sleep on. */ 87 88 /* 89 * MPSAFE 90 */ 91 /* ARGSUSED */ 92 int 93 fork(td, uap) 94 struct thread *td; 95 struct fork_args *uap; 96 { 97 int error; 98 struct proc *p2; 99 100 mtx_lock(&Giant); 101 error = fork1(td, RFFDG | RFPROC, 0, &p2); 102 if (error == 0) { 103 td->td_retval[0] = p2->p_pid; 104 td->td_retval[1] = 0; 105 } 106 mtx_unlock(&Giant); 107 return error; 108 } 109 110 /* 111 * MPSAFE 112 */ 113 /* ARGSUSED */ 114 int 115 vfork(td, uap) 116 struct thread *td; 117 struct vfork_args *uap; 118 { 119 int error; 120 struct proc *p2; 121 122 mtx_lock(&Giant); 123 error = fork1(td, RFFDG | RFPROC | RFPPWAIT | RFMEM, 0, &p2); 124 if (error == 0) { 125 td->td_retval[0] = p2->p_pid; 126 td->td_retval[1] = 0; 127 } 128 mtx_unlock(&Giant); 129 return error; 130 } 131 132 /* 133 * MPSAFE 134 */ 135 int 136 rfork(td, uap) 137 struct thread *td; 138 struct rfork_args *uap; 139 { 140 int error; 141 struct proc *p2; 142 143 /* Don't allow kernel only flags. */ 144 if ((uap->flags & RFKERNELONLY) != 0) 145 return (EINVAL); 146 /* 147 * Don't allow sharing of file descriptor table unless 148 * RFTHREAD flag is supplied 149 */ 150 if ((uap->flags & (RFPROC | RFTHREAD | RFFDG | RFCFDG)) == 151 RFPROC) 152 return(EINVAL); 153 mtx_lock(&Giant); 154 error = fork1(td, uap->flags, 0, &p2); 155 if (error == 0) { 156 td->td_retval[0] = p2 ? p2->p_pid : 0; 157 td->td_retval[1] = 0; 158 } 159 mtx_unlock(&Giant); 160 return error; 161 } 162 163 164 int nprocs = 1; /* process 0 */ 165 int lastpid = 0; 166 SYSCTL_INT(_kern, OID_AUTO, lastpid, CTLFLAG_RD, &lastpid, 0, 167 "Last used PID"); 168 169 /* 170 * Random component to lastpid generation. We mix in a random factor to make 171 * it a little harder to predict. We sanity check the modulus value to avoid 172 * doing it in critical paths. Don't let it be too small or we pointlessly 173 * waste randomness entropy, and don't let it be impossibly large. Using a 174 * modulus that is too big causes a LOT more process table scans and slows 175 * down fork processing as the pidchecked caching is defeated. 176 */ 177 static int randompid = 0; 178 179 static int 180 sysctl_kern_randompid(SYSCTL_HANDLER_ARGS) 181 { 182 int error, pid; 183 184 sysctl_wire_old_buffer(req, sizeof(int)); 185 sx_xlock(&allproc_lock); 186 pid = randompid; 187 error = sysctl_handle_int(oidp, &pid, 0, req); 188 if (error == 0 && req->newptr != NULL) { 189 if (pid < 0 || pid > PID_MAX - 100) /* out of range */ 190 pid = PID_MAX - 100; 191 else if (pid < 2) /* NOP */ 192 pid = 0; 193 else if (pid < 100) /* Make it reasonable */ 194 pid = 100; 195 randompid = pid; 196 } 197 sx_xunlock(&allproc_lock); 198 return (error); 199 } 200 201 SYSCTL_PROC(_kern, OID_AUTO, randompid, CTLTYPE_INT|CTLFLAG_RW, 202 0, 0, sysctl_kern_randompid, "I", "Random PID modulus"); 203 204 int 205 fork1(td, flags, pages, procp) 206 struct thread *td; /* parent proc */ 207 int flags; 208 int pages; 209 struct proc **procp; /* child proc */ 210 { 211 struct proc *p2, *pptr; 212 uid_t uid; 213 struct proc *newproc; 214 int trypid; 215 int ok; 216 static int pidchecked = 0; 217 struct filedesc *fd; 218 struct proc *p1 = td->td_proc; 219 struct thread *td2; 220 struct kse *ke2; 221 struct ksegrp *kg2; 222 struct sigacts *newsigacts; 223 struct procsig *newprocsig; 224 int error; 225 226 GIANT_REQUIRED; 227 228 /* Can't copy and clear */ 229 if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG)) 230 return (EINVAL); 231 232 /* 233 * Here we don't create a new process, but we divorce 234 * certain parts of a process from itself. 235 */ 236 if ((flags & RFPROC) == 0) { 237 vm_forkproc(td, NULL, NULL, flags); 238 239 /* 240 * Close all file descriptors. 241 */ 242 if (flags & RFCFDG) { 243 struct filedesc *fdtmp; 244 fdtmp = fdinit(td->td_proc->p_fd); 245 fdfree(td); 246 p1->p_fd = fdtmp; 247 } 248 249 /* 250 * Unshare file descriptors (from parent.) 251 */ 252 if (flags & RFFDG) { 253 FILEDESC_LOCK(p1->p_fd); 254 if (p1->p_fd->fd_refcnt > 1) { 255 struct filedesc *newfd; 256 257 newfd = fdcopy(td->td_proc->p_fd); 258 FILEDESC_UNLOCK(p1->p_fd); 259 fdfree(td); 260 p1->p_fd = newfd; 261 } else 262 FILEDESC_UNLOCK(p1->p_fd); 263 } 264 *procp = NULL; 265 return (0); 266 } 267 268 if (p1->p_flag & P_THREADED) { 269 /* 270 * Idle the other threads for a second. 271 * Since the user space is copied, it must remain stable. 272 * In addition, all threads (from the user perspective) 273 * need to either be suspended or in the kernel, 274 * where they will try restart in the parent and will 275 * be aborted in the child. 276 */ 277 PROC_LOCK(p1); 278 if (thread_single(SINGLE_NO_EXIT)) { 279 /* Abort.. someone else is single threading before us */ 280 PROC_UNLOCK(p1); 281 return (ERESTART); 282 } 283 PROC_UNLOCK(p1); 284 /* 285 * All other activity in this process 286 * is now suspended at the user boundary, 287 * (or other safe places if we think of any). 288 */ 289 } 290 291 /* Allocate new proc. */ 292 newproc = uma_zalloc(proc_zone, M_WAITOK); 293 #ifdef MAC 294 mac_init_proc(newproc); 295 #endif 296 297 /* 298 * Although process entries are dynamically created, we still keep 299 * a global limit on the maximum number we will create. Don't allow 300 * a nonprivileged user to use the last ten processes; don't let root 301 * exceed the limit. The variable nprocs is the current number of 302 * processes, maxproc is the limit. 303 */ 304 sx_xlock(&allproc_lock); 305 uid = td->td_ucred->cr_ruid; 306 if ((nprocs >= maxproc - 10 && uid != 0) || nprocs >= maxproc) { 307 error = EAGAIN; 308 goto fail; 309 } 310 311 /* 312 * Increment the count of procs running with this uid. Don't allow 313 * a nonprivileged user to exceed their current limit. 314 */ 315 PROC_LOCK(p1); 316 ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1, 317 (uid != 0) ? p1->p_rlimit[RLIMIT_NPROC].rlim_cur : 0); 318 PROC_UNLOCK(p1); 319 if (!ok) { 320 error = EAGAIN; 321 goto fail; 322 } 323 324 /* 325 * Increment the nprocs resource before blocking can occur. There 326 * are hard-limits as to the number of processes that can run. 327 */ 328 nprocs++; 329 330 /* 331 * Find an unused process ID. We remember a range of unused IDs 332 * ready to use (from lastpid+1 through pidchecked-1). 333 * 334 * If RFHIGHPID is set (used during system boot), do not allocate 335 * low-numbered pids. 336 */ 337 trypid = lastpid + 1; 338 if (flags & RFHIGHPID) { 339 if (trypid < 10) { 340 trypid = 10; 341 } 342 } else { 343 if (randompid) 344 trypid += arc4random() % randompid; 345 } 346 retry: 347 /* 348 * If the process ID prototype has wrapped around, 349 * restart somewhat above 0, as the low-numbered procs 350 * tend to include daemons that don't exit. 351 */ 352 if (trypid >= PID_MAX) { 353 trypid = trypid % PID_MAX; 354 if (trypid < 100) 355 trypid += 100; 356 pidchecked = 0; 357 } 358 if (trypid >= pidchecked) { 359 int doingzomb = 0; 360 361 pidchecked = PID_MAX; 362 /* 363 * Scan the active and zombie procs to check whether this pid 364 * is in use. Remember the lowest pid that's greater 365 * than trypid, so we can avoid checking for a while. 366 */ 367 p2 = LIST_FIRST(&allproc); 368 again: 369 for (; p2 != NULL; p2 = LIST_NEXT(p2, p_list)) { 370 PROC_LOCK(p2); 371 while (p2->p_pid == trypid || 372 p2->p_pgrp->pg_id == trypid || 373 p2->p_session->s_sid == trypid) { 374 trypid++; 375 if (trypid >= pidchecked) { 376 PROC_UNLOCK(p2); 377 goto retry; 378 } 379 } 380 if (p2->p_pid > trypid && pidchecked > p2->p_pid) 381 pidchecked = p2->p_pid; 382 if (p2->p_pgrp->pg_id > trypid && 383 pidchecked > p2->p_pgrp->pg_id) 384 pidchecked = p2->p_pgrp->pg_id; 385 if (p2->p_session->s_sid > trypid && 386 pidchecked > p2->p_session->s_sid) 387 pidchecked = p2->p_session->s_sid; 388 PROC_UNLOCK(p2); 389 } 390 if (!doingzomb) { 391 doingzomb = 1; 392 p2 = LIST_FIRST(&zombproc); 393 goto again; 394 } 395 } 396 397 /* 398 * RFHIGHPID does not mess with the lastpid counter during boot. 399 */ 400 if (flags & RFHIGHPID) 401 pidchecked = 0; 402 else 403 lastpid = trypid; 404 405 p2 = newproc; 406 p2->p_state = PRS_NEW; /* protect against others */ 407 p2->p_pid = trypid; 408 LIST_INSERT_HEAD(&allproc, p2, p_list); 409 LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash); 410 sx_xunlock(&allproc_lock); 411 412 /* 413 * Malloc things while we don't hold any locks. 414 */ 415 if (flags & RFSIGSHARE) { 416 MALLOC(newsigacts, struct sigacts *, 417 sizeof(struct sigacts), M_SUBPROC, M_WAITOK); 418 newprocsig = NULL; 419 } else { 420 newsigacts = NULL; 421 MALLOC(newprocsig, struct procsig *, sizeof(struct procsig), 422 M_SUBPROC, M_WAITOK); 423 } 424 425 /* 426 * Copy filedesc. 427 * XXX: This is busted. fd*() need to not take proc 428 * arguments or something. 429 */ 430 if (flags & RFCFDG) 431 fd = fdinit(td->td_proc->p_fd); 432 else if (flags & RFFDG) { 433 FILEDESC_LOCK(p1->p_fd); 434 fd = fdcopy(td->td_proc->p_fd); 435 FILEDESC_UNLOCK(p1->p_fd); 436 } else 437 fd = fdshare(p1->p_fd); 438 439 /* 440 * Make a proc table entry for the new process. 441 * Start by zeroing the section of proc that is zero-initialized, 442 * then copy the section that is copied directly from the parent. 443 */ 444 td2 = FIRST_THREAD_IN_PROC(p2); 445 kg2 = FIRST_KSEGRP_IN_PROC(p2); 446 ke2 = FIRST_KSE_IN_KSEGRP(kg2); 447 448 /* Allocate and switch to an alternate kstack if specified */ 449 if (pages != 0) 450 pmap_new_altkstack(td2, pages); 451 452 #define RANGEOF(type, start, end) (offsetof(type, end) - offsetof(type, start)) 453 454 bzero(&p2->p_startzero, 455 (unsigned) RANGEOF(struct proc, p_startzero, p_endzero)); 456 bzero(&ke2->ke_startzero, 457 (unsigned) RANGEOF(struct kse, ke_startzero, ke_endzero)); 458 bzero(&td2->td_startzero, 459 (unsigned) RANGEOF(struct thread, td_startzero, td_endzero)); 460 bzero(&kg2->kg_startzero, 461 (unsigned) RANGEOF(struct ksegrp, kg_startzero, kg_endzero)); 462 463 mtx_init(&p2->p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); 464 PROC_LOCK(p2); 465 PROC_LOCK(p1); 466 467 bcopy(&p1->p_startcopy, &p2->p_startcopy, 468 (unsigned) RANGEOF(struct proc, p_startcopy, p_endcopy)); 469 bcopy(&td->td_startcopy, &td2->td_startcopy, 470 (unsigned) RANGEOF(struct thread, td_startcopy, td_endcopy)); 471 bcopy(&td->td_ksegrp->kg_startcopy, &kg2->kg_startcopy, 472 (unsigned) RANGEOF(struct ksegrp, kg_startcopy, kg_endcopy)); 473 #undef RANGEOF 474 475 /* Set up the thread as an active thread (as if runnable). */ 476 ke2->ke_state = KES_THREAD; 477 ke2->ke_thread = td2; 478 td2->td_kse = ke2; 479 480 /* 481 * Duplicate sub-structures as needed. 482 * Increase reference counts on shared objects. 483 * The p_stats and p_sigacts substructs are set in vm_forkproc. 484 */ 485 p2->p_flag = 0; 486 mtx_lock_spin(&sched_lock); 487 p2->p_sflag = PS_INMEM; 488 if (p1->p_sflag & PS_PROFIL) 489 startprofclock(p2); 490 /* 491 * Allow the scheduler to adjust the priority of the child and 492 * parent while we hold the sched_lock. 493 */ 494 sched_fork(td->td_ksegrp, kg2); 495 496 mtx_unlock_spin(&sched_lock); 497 p2->p_ucred = crhold(td->td_ucred); 498 td2->td_ucred = crhold(p2->p_ucred); /* XXXKSE */ 499 500 pargs_hold(p2->p_args); 501 502 if (flags & RFSIGSHARE) { 503 p2->p_procsig = p1->p_procsig; 504 p2->p_procsig->ps_refcnt++; 505 if (p1->p_sigacts == &p1->p_uarea->u_sigacts) { 506 /* 507 * Set p_sigacts to the new shared structure. 508 * Note that this is updating p1->p_sigacts at the 509 * same time, since p_sigacts is just a pointer to 510 * the shared p_procsig->ps_sigacts. 511 */ 512 p2->p_sigacts = newsigacts; 513 newsigacts = NULL; 514 *p2->p_sigacts = p1->p_uarea->u_sigacts; 515 } 516 } else { 517 p2->p_procsig = newprocsig; 518 newprocsig = NULL; 519 bcopy(p1->p_procsig, p2->p_procsig, sizeof(*p2->p_procsig)); 520 p2->p_procsig->ps_refcnt = 1; 521 p2->p_sigacts = NULL; /* finished in vm_forkproc() */ 522 } 523 if (flags & RFLINUXTHPN) 524 p2->p_sigparent = SIGUSR1; 525 else 526 p2->p_sigparent = SIGCHLD; 527 528 /* Bump references to the text vnode (for procfs) */ 529 p2->p_textvp = p1->p_textvp; 530 if (p2->p_textvp) 531 VREF(p2->p_textvp); 532 p2->p_fd = fd; 533 PROC_UNLOCK(p1); 534 PROC_UNLOCK(p2); 535 536 /* 537 * p_limit is copy-on-write, bump refcnt, 538 */ 539 p2->p_limit = p1->p_limit; 540 p2->p_limit->p_refcnt++; 541 542 /* 543 * Setup linkage for kernel based threading 544 */ 545 if((flags & RFTHREAD) != 0) { 546 mtx_lock(&ppeers_lock); 547 p2->p_peers = p1->p_peers; 548 p1->p_peers = p2; 549 p2->p_leader = p1->p_leader; 550 mtx_unlock(&ppeers_lock); 551 PROC_LOCK(p1->p_leader); 552 if ((p1->p_leader->p_flag & P_WEXIT) != 0) { 553 PROC_UNLOCK(p1->p_leader); 554 /* 555 * The task leader is exiting, so process p1 is 556 * going to be killed shortly. Since p1 obviously 557 * isn't dead yet, we know that the leader is either 558 * sending SIGKILL's to all the processes in this 559 * task or is sleeping waiting for all the peers to 560 * exit. We let p1 complete the fork, but we need 561 * to go ahead and kill the new process p2 since 562 * the task leader may not get a chance to send 563 * SIGKILL to it. We leave it on the list so that 564 * the task leader will wait for this new process 565 * to commit suicide. 566 */ 567 PROC_LOCK(p2); 568 psignal(p2, SIGKILL); 569 PROC_UNLOCK(p2); 570 } else 571 PROC_UNLOCK(p1->p_leader); 572 } else { 573 p2->p_peers = NULL; 574 p2->p_leader = p2; 575 } 576 577 sx_xlock(&proctree_lock); 578 PGRP_LOCK(p1->p_pgrp); 579 PROC_LOCK(p2); 580 PROC_LOCK(p1); 581 582 /* 583 * Preserve some more flags in subprocess. PS_PROFIL has already 584 * been preserved. 585 */ 586 p2->p_flag |= p1->p_flag & (P_SUGID | P_ALTSTACK); 587 SESS_LOCK(p1->p_session); 588 if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT) 589 p2->p_flag |= P_CONTROLT; 590 SESS_UNLOCK(p1->p_session); 591 if (flags & RFPPWAIT) 592 p2->p_flag |= P_PPWAIT; 593 594 LIST_INSERT_AFTER(p1, p2, p_pglist); 595 PGRP_UNLOCK(p1->p_pgrp); 596 LIST_INIT(&p2->p_children); 597 598 callout_init(&p2->p_itcallout, 0); 599 600 #ifdef KTRACE 601 /* 602 * Copy traceflag and tracefile if enabled. 603 */ 604 mtx_lock(&ktrace_mtx); 605 KASSERT(p2->p_tracevp == NULL, ("new process has a ktrace vnode")); 606 if (p1->p_traceflag & KTRFAC_INHERIT) { 607 p2->p_traceflag = p1->p_traceflag; 608 if ((p2->p_tracevp = p1->p_tracevp) != NULL) { 609 VREF(p2->p_tracevp); 610 KASSERT(p1->p_tracecred != NULL, 611 ("ktrace vnode with no cred")); 612 p2->p_tracecred = crhold(p1->p_tracecred); 613 } 614 } 615 mtx_unlock(&ktrace_mtx); 616 #endif 617 618 /* 619 * If PF_FORK is set, the child process inherits the 620 * procfs ioctl flags from its parent. 621 */ 622 if (p1->p_pfsflags & PF_FORK) { 623 p2->p_stops = p1->p_stops; 624 p2->p_pfsflags = p1->p_pfsflags; 625 } 626 627 /* 628 * This begins the section where we must prevent the parent 629 * from being swapped. 630 */ 631 _PHOLD(p1); 632 PROC_UNLOCK(p1); 633 634 /* 635 * Attach the new process to its parent. 636 * 637 * If RFNOWAIT is set, the newly created process becomes a child 638 * of init. This effectively disassociates the child from the 639 * parent. 640 */ 641 if (flags & RFNOWAIT) 642 pptr = initproc; 643 else 644 pptr = p1; 645 p2->p_pptr = pptr; 646 LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling); 647 PROC_UNLOCK(p2); 648 sx_xunlock(&proctree_lock); 649 650 KASSERT(newprocsig == NULL, ("unused newprocsig")); 651 if (newsigacts != NULL) 652 FREE(newsigacts, M_SUBPROC); 653 /* 654 * Finish creating the child process. It will return via a different 655 * execution path later. (ie: directly into user mode) 656 */ 657 vm_forkproc(td, p2, td2, flags); 658 659 if (flags == (RFFDG | RFPROC)) { 660 cnt.v_forks++; 661 cnt.v_forkpages += p2->p_vmspace->vm_dsize + 662 p2->p_vmspace->vm_ssize; 663 } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM)) { 664 cnt.v_vforks++; 665 cnt.v_vforkpages += p2->p_vmspace->vm_dsize + 666 p2->p_vmspace->vm_ssize; 667 } else if (p1 == &proc0) { 668 cnt.v_kthreads++; 669 cnt.v_kthreadpages += p2->p_vmspace->vm_dsize + 670 p2->p_vmspace->vm_ssize; 671 } else { 672 cnt.v_rforks++; 673 cnt.v_rforkpages += p2->p_vmspace->vm_dsize + 674 p2->p_vmspace->vm_ssize; 675 } 676 677 /* 678 * Both processes are set up, now check if any loadable modules want 679 * to adjust anything. 680 * What if they have an error? XXX 681 */ 682 EVENTHANDLER_INVOKE(process_fork, p1, p2, flags); 683 684 /* 685 * If RFSTOPPED not requested, make child runnable and add to 686 * run queue. 687 */ 688 microtime(&(p2->p_stats->p_start)); 689 p2->p_acflag = AFORK; 690 if ((flags & RFSTOPPED) == 0) { 691 mtx_lock_spin(&sched_lock); 692 p2->p_state = PRS_NORMAL; 693 TD_SET_CAN_RUN(td2); 694 setrunqueue(td2); 695 mtx_unlock_spin(&sched_lock); 696 } 697 698 /* 699 * Now can be swapped. 700 */ 701 PROC_LOCK(p1); 702 _PRELE(p1); 703 704 /* 705 * tell any interested parties about the new process 706 */ 707 KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid); 708 PROC_UNLOCK(p1); 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 PROC_LOCK(p2); 716 while (p2->p_flag & P_PPWAIT) 717 msleep(p1, &p2->p_mtx, PWAIT, "ppwait", 0); 718 PROC_UNLOCK(p2); 719 720 /* 721 * If other threads are waiting, let them continue now 722 */ 723 if (p1->p_flag & P_THREADED) { 724 PROC_LOCK(p1); 725 thread_single_end(); 726 PROC_UNLOCK(p1); 727 } 728 729 /* 730 * Return child proc pointer to parent. 731 */ 732 *procp = p2; 733 return (0); 734 fail: 735 sx_xunlock(&allproc_lock); 736 uma_zfree(proc_zone, newproc); 737 if (p1->p_flag & P_THREADED) { 738 PROC_LOCK(p1); 739 thread_single_end(); 740 PROC_UNLOCK(p1); 741 } 742 tsleep(&forksleep, PUSER, "fork", hz / 2); 743 return (error); 744 } 745 746 /* 747 * Handle the return of a child process from fork1(). This function 748 * is called from the MD fork_trampoline() entry point. 749 */ 750 void 751 fork_exit(callout, arg, frame) 752 void (*callout)(void *, struct trapframe *); 753 void *arg; 754 struct trapframe *frame; 755 { 756 struct thread *td; 757 struct proc *p; 758 759 if ((td = PCPU_GET(deadthread))) { 760 PCPU_SET(deadthread, NULL); 761 thread_stash(td); 762 } 763 td = curthread; 764 p = td->td_proc; 765 td->td_kse->ke_oncpu = PCPU_GET(cpuid); 766 p->p_state = PRS_NORMAL; 767 /* 768 * Finish setting up thread glue. We need to initialize 769 * the thread into a td_critnest=1 state. Some platforms 770 * may have already partially or fully initialized td_critnest 771 * and/or td_md.md_savecrit (when applciable). 772 * 773 * see <arch>/<arch>/critical.c 774 */ 775 sched_lock.mtx_lock = (uintptr_t)td; 776 sched_lock.mtx_recurse = 0; 777 cpu_critical_fork_exit(); 778 CTR3(KTR_PROC, "fork_exit: new thread %p (pid %d, %s)", td, p->p_pid, 779 p->p_comm); 780 if (PCPU_GET(switchtime.sec) == 0) 781 binuptime(PCPU_PTR(switchtime)); 782 PCPU_SET(switchticks, ticks); 783 mtx_unlock_spin(&sched_lock); 784 785 /* 786 * cpu_set_fork_handler intercepts this function call to 787 * have this call a non-return function to stay in kernel mode. 788 * initproc has its own fork handler, but it does return. 789 */ 790 KASSERT(callout != NULL, ("NULL callout in fork_exit")); 791 callout(arg, frame); 792 793 /* 794 * Check if a kernel thread misbehaved and returned from its main 795 * function. 796 */ 797 PROC_LOCK(p); 798 if (p->p_flag & P_KTHREAD) { 799 PROC_UNLOCK(p); 800 mtx_lock(&Giant); 801 printf("Kernel thread \"%s\" (pid %d) exited prematurely.\n", 802 p->p_comm, p->p_pid); 803 kthread_exit(0); 804 } 805 PROC_UNLOCK(p); 806 #ifdef DIAGNOSTIC 807 cred_free_thread(td); 808 #endif 809 mtx_assert(&Giant, MA_NOTOWNED); 810 } 811 812 /* 813 * Simplified back end of syscall(), used when returning from fork() 814 * directly into user mode. Giant is not held on entry, and must not 815 * be held on return. This function is passed in to fork_exit() as the 816 * first parameter and is called when returning to a new userland process. 817 */ 818 void 819 fork_return(td, frame) 820 struct thread *td; 821 struct trapframe *frame; 822 { 823 824 userret(td, frame, 0); 825 #ifdef KTRACE 826 if (KTRPOINT(td, KTR_SYSRET)) 827 ktrsysret(SYS_fork, 0, 0); 828 #endif 829 mtx_assert(&Giant, MA_NOTOWNED); 830 } 831