kern_exit.c revision 220526
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 * 4. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)kern_exit.c 8.7 (Berkeley) 2/12/94 35 */ 36 37#include <sys/cdefs.h> 38__FBSDID("$FreeBSD: head/sys/kern/kern_exit.c 220526 2011-04-10 17:07:02Z kib $"); 39 40#include "opt_compat.h" 41#include "opt_kdtrace.h" 42#include "opt_ktrace.h" 43 44#include <sys/param.h> 45#include <sys/systm.h> 46#include <sys/sysproto.h> 47#include <sys/eventhandler.h> 48#include <sys/kernel.h> 49#include <sys/malloc.h> 50#include <sys/lock.h> 51#include <sys/mutex.h> 52#include <sys/proc.h> 53#include <sys/pioctl.h> 54#include <sys/jail.h> 55#include <sys/tty.h> 56#include <sys/wait.h> 57#include <sys/vmmeter.h> 58#include <sys/vnode.h> 59#include <sys/racct.h> 60#include <sys/resourcevar.h> 61#include <sys/sbuf.h> 62#include <sys/signalvar.h> 63#include <sys/sched.h> 64#include <sys/sx.h> 65#include <sys/syscallsubr.h> 66#include <sys/syslog.h> 67#include <sys/ptrace.h> 68#include <sys/acct.h> /* for acct_process() function prototype */ 69#include <sys/filedesc.h> 70#include <sys/sdt.h> 71#include <sys/shm.h> 72#include <sys/sem.h> 73#ifdef KTRACE 74#include <sys/ktrace.h> 75#endif 76 77#include <security/audit/audit.h> 78#include <security/mac/mac_framework.h> 79 80#include <vm/vm.h> 81#include <vm/vm_extern.h> 82#include <vm/vm_param.h> 83#include <vm/pmap.h> 84#include <vm/vm_map.h> 85#include <vm/vm_page.h> 86#include <vm/uma.h> 87 88#ifdef KDTRACE_HOOKS 89#include <sys/dtrace_bsd.h> 90dtrace_execexit_func_t dtrace_fasttrap_exit; 91#endif 92 93SDT_PROVIDER_DECLARE(proc); 94SDT_PROBE_DEFINE(proc, kernel, , exit, exit); 95SDT_PROBE_ARGTYPE(proc, kernel, , exit, 0, "int"); 96 97/* Required to be non-static for SysVR4 emulator */ 98MALLOC_DEFINE(M_ZOMBIE, "zombie", "zombie proc status"); 99 100/* Hook for NFS teardown procedure. */ 101void (*nlminfo_release_p)(struct proc *p); 102 103/* 104 * exit -- death of process. 105 */ 106void 107sys_exit(struct thread *td, struct sys_exit_args *uap) 108{ 109 110 exit1(td, W_EXITCODE(uap->rval, 0)); 111 /* NOTREACHED */ 112} 113 114/* 115 * Exit: deallocate address space and other resources, change proc state to 116 * zombie, and unlink proc from allproc and parent's lists. Save exit status 117 * and rusage for wait(). Check for child processes and orphan them. 118 */ 119void 120exit1(struct thread *td, int rv) 121{ 122 struct proc *p, *nq, *q; 123 struct vnode *vtmp; 124 struct vnode *ttyvp = NULL; 125 struct plimit *plim; 126 int locked; 127 128 mtx_assert(&Giant, MA_NOTOWNED); 129 130 p = td->td_proc; 131 /* 132 * XXX in case we're rebooting we just let init die in order to 133 * work around an unsolved stack overflow seen very late during 134 * shutdown on sparc64 when the gmirror worker process exists. 135 */ 136 if (p == initproc && rebooting == 0) { 137 printf("init died (signal %d, exit %d)\n", 138 WTERMSIG(rv), WEXITSTATUS(rv)); 139 panic("Going nowhere without my init!"); 140 } 141 142 /* 143 * MUST abort all other threads before proceeding past here. 144 */ 145 PROC_LOCK(p); 146 while (p->p_flag & P_HADTHREADS) { 147 /* 148 * First check if some other thread got here before us.. 149 * if so, act apropriatly, (exit or suspend); 150 */ 151 thread_suspend_check(0); 152 153 /* 154 * Kill off the other threads. This requires 155 * some co-operation from other parts of the kernel 156 * so it may not be instantaneous. With this state set 157 * any thread entering the kernel from userspace will 158 * thread_exit() in trap(). Any thread attempting to 159 * sleep will return immediately with EINTR or EWOULDBLOCK 160 * which will hopefully force them to back out to userland 161 * freeing resources as they go. Any thread attempting 162 * to return to userland will thread_exit() from userret(). 163 * thread_exit() will unsuspend us when the last of the 164 * other threads exits. 165 * If there is already a thread singler after resumption, 166 * calling thread_single will fail; in that case, we just 167 * re-check all suspension request, the thread should 168 * either be suspended there or exit. 169 */ 170 if (! thread_single(SINGLE_EXIT)) 171 break; 172 173 /* 174 * All other activity in this process is now stopped. 175 * Threading support has been turned off. 176 */ 177 } 178 KASSERT(p->p_numthreads == 1, 179 ("exit1: proc %p exiting with %d threads", p, p->p_numthreads)); 180 racct_sub(p, RACCT_NTHR, 1); 181 /* 182 * Wakeup anyone in procfs' PIOCWAIT. They should have a hold 183 * on our vmspace, so we should block below until they have 184 * released their reference to us. Note that if they have 185 * requested S_EXIT stops we will block here until they ack 186 * via PIOCCONT. 187 */ 188 _STOPEVENT(p, S_EXIT, rv); 189 190 /* 191 * Note that we are exiting and do another wakeup of anyone in 192 * PIOCWAIT in case they aren't listening for S_EXIT stops or 193 * decided to wait again after we told them we are exiting. 194 */ 195 p->p_flag |= P_WEXIT; 196 wakeup(&p->p_stype); 197 198 /* 199 * Wait for any processes that have a hold on our vmspace to 200 * release their reference. 201 */ 202 while (p->p_lock > 0) 203 msleep(&p->p_lock, &p->p_mtx, PWAIT, "exithold", 0); 204 205 p->p_xstat = rv; /* Let event handler change exit status */ 206 PROC_UNLOCK(p); 207 /* Drain the limit callout while we don't have the proc locked */ 208 callout_drain(&p->p_limco); 209 210#ifdef AUDIT 211 /* 212 * The Sun BSM exit token contains two components: an exit status as 213 * passed to exit(), and a return value to indicate what sort of exit 214 * it was. The exit status is WEXITSTATUS(rv), but it's not clear 215 * what the return value is. 216 */ 217 AUDIT_ARG_EXIT(WEXITSTATUS(rv), 0); 218 AUDIT_SYSCALL_EXIT(0, td); 219#endif 220 221 /* Are we a task leader? */ 222 if (p == p->p_leader) { 223 mtx_lock(&ppeers_lock); 224 q = p->p_peers; 225 while (q != NULL) { 226 PROC_LOCK(q); 227 psignal(q, SIGKILL); 228 PROC_UNLOCK(q); 229 q = q->p_peers; 230 } 231 while (p->p_peers != NULL) 232 msleep(p, &ppeers_lock, PWAIT, "exit1", 0); 233 mtx_unlock(&ppeers_lock); 234 } 235 236 /* 237 * Check if any loadable modules need anything done at process exit. 238 * E.g. SYSV IPC stuff 239 * XXX what if one of these generates an error? 240 */ 241 EVENTHANDLER_INVOKE(process_exit, p); 242 243 /* 244 * If parent is waiting for us to exit or exec, 245 * P_PPWAIT is set; we will wakeup the parent below. 246 */ 247 PROC_LOCK(p); 248 rv = p->p_xstat; /* Event handler could change exit status */ 249 stopprofclock(p); 250 p->p_flag &= ~(P_TRACED | P_PPWAIT); 251 252 /* 253 * Stop the real interval timer. If the handler is currently 254 * executing, prevent it from rearming itself and let it finish. 255 */ 256 if (timevalisset(&p->p_realtimer.it_value) && 257 callout_stop(&p->p_itcallout) == 0) { 258 timevalclear(&p->p_realtimer.it_interval); 259 msleep(&p->p_itcallout, &p->p_mtx, PWAIT, "ritwait", 0); 260 KASSERT(!timevalisset(&p->p_realtimer.it_value), 261 ("realtime timer is still armed")); 262 } 263 PROC_UNLOCK(p); 264 265 /* 266 * Reset any sigio structures pointing to us as a result of 267 * F_SETOWN with our pid. 268 */ 269 funsetownlst(&p->p_sigiolst); 270 271 /* 272 * If this process has an nlminfo data area (for lockd), release it 273 */ 274 if (nlminfo_release_p != NULL && p->p_nlminfo != NULL) 275 (*nlminfo_release_p)(p); 276 277 /* 278 * Close open files and release open-file table. 279 * This may block! 280 */ 281 fdfree(td); 282 283 /* 284 * If this thread tickled GEOM, we need to wait for the giggling to 285 * stop before we return to userland 286 */ 287 if (td->td_pflags & TDP_GEOM) 288 g_waitidle(); 289 290 /* 291 * Remove ourself from our leader's peer list and wake our leader. 292 */ 293 mtx_lock(&ppeers_lock); 294 if (p->p_leader->p_peers) { 295 q = p->p_leader; 296 while (q->p_peers != p) 297 q = q->p_peers; 298 q->p_peers = p->p_peers; 299 wakeup(p->p_leader); 300 } 301 mtx_unlock(&ppeers_lock); 302 303 vmspace_exit(td); 304 305 sx_xlock(&proctree_lock); 306 if (SESS_LEADER(p)) { 307 struct session *sp = p->p_session; 308 struct tty *tp; 309 310 /* 311 * s_ttyp is not zero'd; we use this to indicate that 312 * the session once had a controlling terminal. (for 313 * logging and informational purposes) 314 */ 315 SESS_LOCK(sp); 316 ttyvp = sp->s_ttyvp; 317 tp = sp->s_ttyp; 318 sp->s_ttyvp = NULL; 319 sp->s_ttydp = NULL; 320 sp->s_leader = NULL; 321 SESS_UNLOCK(sp); 322 323 /* 324 * Signal foreground pgrp and revoke access to 325 * controlling terminal if it has not been revoked 326 * already. 327 * 328 * Because the TTY may have been revoked in the mean 329 * time and could already have a new session associated 330 * with it, make sure we don't send a SIGHUP to a 331 * foreground process group that does not belong to this 332 * session. 333 */ 334 335 if (tp != NULL) { 336 tty_lock(tp); 337 if (tp->t_session == sp) 338 tty_signal_pgrp(tp, SIGHUP); 339 tty_unlock(tp); 340 } 341 342 if (ttyvp != NULL) { 343 sx_xunlock(&proctree_lock); 344 if (vn_lock(ttyvp, LK_EXCLUSIVE) == 0) { 345 VOP_REVOKE(ttyvp, REVOKEALL); 346 VOP_UNLOCK(ttyvp, 0); 347 } 348 sx_xlock(&proctree_lock); 349 } 350 } 351 fixjobc(p, p->p_pgrp, 0); 352 sx_xunlock(&proctree_lock); 353 (void)acct_process(td); 354 355 /* Release the TTY now we've unlocked everything. */ 356 if (ttyvp != NULL) 357 vrele(ttyvp); 358#ifdef KTRACE 359 ktrprocexit(td); 360#endif 361 /* 362 * Release reference to text vnode 363 */ 364 if ((vtmp = p->p_textvp) != NULL) { 365 p->p_textvp = NULL; 366 locked = VFS_LOCK_GIANT(vtmp->v_mount); 367 vrele(vtmp); 368 VFS_UNLOCK_GIANT(locked); 369 } 370 371 /* 372 * Release our limits structure. 373 */ 374 PROC_LOCK(p); 375 plim = p->p_limit; 376 p->p_limit = NULL; 377 PROC_UNLOCK(p); 378 lim_free(plim); 379 380 tidhash_remove(td); 381 382 /* 383 * Remove proc from allproc queue and pidhash chain. 384 * Place onto zombproc. Unlink from parent's child list. 385 */ 386 sx_xlock(&allproc_lock); 387 LIST_REMOVE(p, p_list); 388 LIST_INSERT_HEAD(&zombproc, p, p_list); 389 LIST_REMOVE(p, p_hash); 390 sx_xunlock(&allproc_lock); 391 392 /* 393 * Call machine-dependent code to release any 394 * machine-dependent resources other than the address space. 395 * The address space is released by "vmspace_exitfree(p)" in 396 * vm_waitproc(). 397 */ 398 cpu_exit(td); 399 400 WITNESS_WARN(WARN_PANIC, NULL, "process (pid %d) exiting", p->p_pid); 401 402 /* 403 * Reparent all of our children to init. 404 */ 405 sx_xlock(&proctree_lock); 406 q = LIST_FIRST(&p->p_children); 407 if (q != NULL) /* only need this if any child is S_ZOMB */ 408 wakeup(initproc); 409 for (; q != NULL; q = nq) { 410 nq = LIST_NEXT(q, p_sibling); 411 PROC_LOCK(q); 412 proc_reparent(q, initproc); 413 q->p_sigparent = SIGCHLD; 414 /* 415 * Traced processes are killed 416 * since their existence means someone is screwing up. 417 */ 418 if (q->p_flag & P_TRACED) { 419 struct thread *temp; 420 421 q->p_flag &= ~(P_TRACED | P_STOPPED_TRACE); 422 FOREACH_THREAD_IN_PROC(q, temp) 423 temp->td_dbgflags &= ~TDB_SUSPEND; 424 psignal(q, SIGKILL); 425 } 426 PROC_UNLOCK(q); 427 } 428 429 /* Save exit status. */ 430 PROC_LOCK(p); 431 p->p_xthread = td; 432 433 /* Tell the prison that we are gone. */ 434 prison_proc_free(p->p_ucred->cr_prison); 435 436#ifdef KDTRACE_HOOKS 437 /* 438 * Tell the DTrace fasttrap provider about the exit if it 439 * has declared an interest. 440 */ 441 if (dtrace_fasttrap_exit) 442 dtrace_fasttrap_exit(p); 443#endif 444 445 /* 446 * Notify interested parties of our demise. 447 */ 448 KNOTE_LOCKED(&p->p_klist, NOTE_EXIT); 449 450#ifdef KDTRACE_HOOKS 451 int reason = CLD_EXITED; 452 if (WCOREDUMP(rv)) 453 reason = CLD_DUMPED; 454 else if (WIFSIGNALED(rv)) 455 reason = CLD_KILLED; 456 SDT_PROBE(proc, kernel, , exit, reason, 0, 0, 0, 0); 457#endif 458 459 /* 460 * Just delete all entries in the p_klist. At this point we won't 461 * report any more events, and there are nasty race conditions that 462 * can beat us if we don't. 463 */ 464 knlist_clear(&p->p_klist, 1); 465 466 /* 467 * Notify parent that we're gone. If parent has the PS_NOCLDWAIT 468 * flag set, or if the handler is set to SIG_IGN, notify process 469 * 1 instead (and hope it will handle this situation). 470 */ 471 PROC_LOCK(p->p_pptr); 472 mtx_lock(&p->p_pptr->p_sigacts->ps_mtx); 473 if (p->p_pptr->p_sigacts->ps_flag & (PS_NOCLDWAIT | PS_CLDSIGIGN)) { 474 struct proc *pp; 475 476 mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx); 477 pp = p->p_pptr; 478 PROC_UNLOCK(pp); 479 proc_reparent(p, initproc); 480 p->p_sigparent = SIGCHLD; 481 PROC_LOCK(p->p_pptr); 482 483 /* 484 * Notify parent, so in case he was wait(2)ing or 485 * executing waitpid(2) with our pid, he will 486 * continue. 487 */ 488 wakeup(pp); 489 } else 490 mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx); 491 492 if (p->p_pptr == initproc) 493 psignal(p->p_pptr, SIGCHLD); 494 else if (p->p_sigparent != 0) { 495 if (p->p_sigparent == SIGCHLD) 496 childproc_exited(p); 497 else /* LINUX thread */ 498 psignal(p->p_pptr, p->p_sigparent); 499 } 500 sx_xunlock(&proctree_lock); 501 502 /* 503 * The state PRS_ZOMBIE prevents other proesses from sending 504 * signal to the process, to avoid memory leak, we free memory 505 * for signal queue at the time when the state is set. 506 */ 507 sigqueue_flush(&p->p_sigqueue); 508 sigqueue_flush(&td->td_sigqueue); 509 510 /* 511 * We have to wait until after acquiring all locks before 512 * changing p_state. We need to avoid all possible context 513 * switches (including ones from blocking on a mutex) while 514 * marked as a zombie. We also have to set the zombie state 515 * before we release the parent process' proc lock to avoid 516 * a lost wakeup. So, we first call wakeup, then we grab the 517 * sched lock, update the state, and release the parent process' 518 * proc lock. 519 */ 520 wakeup(p->p_pptr); 521 cv_broadcast(&p->p_pwait); 522 sched_exit(p->p_pptr, td); 523 PROC_SLOCK(p); 524 p->p_state = PRS_ZOMBIE; 525 PROC_UNLOCK(p->p_pptr); 526 527 /* 528 * Hopefully no one will try to deliver a signal to the process this 529 * late in the game. 530 */ 531 knlist_destroy(&p->p_klist); 532 533 /* 534 * Save our children's rusage information in our exit rusage. 535 */ 536 ruadd(&p->p_ru, &p->p_rux, &p->p_stats->p_cru, &p->p_crux); 537 538 /* 539 * Make sure the scheduler takes this thread out of its tables etc. 540 * This will also release this thread's reference to the ucred. 541 * Other thread parts to release include pcb bits and such. 542 */ 543 thread_exit(); 544} 545 546 547#ifndef _SYS_SYSPROTO_H_ 548struct abort2_args { 549 char *why; 550 int nargs; 551 void **args; 552}; 553#endif 554 555int 556abort2(struct thread *td, struct abort2_args *uap) 557{ 558 struct proc *p = td->td_proc; 559 struct sbuf *sb; 560 void *uargs[16]; 561 int error, i, sig; 562 563 /* 564 * Do it right now so we can log either proper call of abort2(), or 565 * note, that invalid argument was passed. 512 is big enough to 566 * handle 16 arguments' descriptions with additional comments. 567 */ 568 sb = sbuf_new(NULL, NULL, 512, SBUF_FIXEDLEN); 569 sbuf_clear(sb); 570 sbuf_printf(sb, "%s(pid %d uid %d) aborted: ", 571 p->p_comm, p->p_pid, td->td_ucred->cr_uid); 572 /* 573 * Since we can't return from abort2(), send SIGKILL in cases, where 574 * abort2() was called improperly 575 */ 576 sig = SIGKILL; 577 /* Prevent from DoSes from user-space. */ 578 if (uap->nargs < 0 || uap->nargs > 16) 579 goto out; 580 if (uap->nargs > 0) { 581 if (uap->args == NULL) 582 goto out; 583 error = copyin(uap->args, uargs, uap->nargs * sizeof(void *)); 584 if (error != 0) 585 goto out; 586 } 587 /* 588 * Limit size of 'reason' string to 128. Will fit even when 589 * maximal number of arguments was chosen to be logged. 590 */ 591 if (uap->why != NULL) { 592 error = sbuf_copyin(sb, uap->why, 128); 593 if (error < 0) 594 goto out; 595 } else { 596 sbuf_printf(sb, "(null)"); 597 } 598 if (uap->nargs > 0) { 599 sbuf_printf(sb, "("); 600 for (i = 0;i < uap->nargs; i++) 601 sbuf_printf(sb, "%s%p", i == 0 ? "" : ", ", uargs[i]); 602 sbuf_printf(sb, ")"); 603 } 604 /* 605 * Final stage: arguments were proper, string has been 606 * successfully copied from userspace, and copying pointers 607 * from user-space succeed. 608 */ 609 sig = SIGABRT; 610out: 611 if (sig == SIGKILL) { 612 sbuf_trim(sb); 613 sbuf_printf(sb, " (Reason text inaccessible)"); 614 } 615 sbuf_cat(sb, "\n"); 616 sbuf_finish(sb); 617 log(LOG_INFO, "%s", sbuf_data(sb)); 618 sbuf_delete(sb); 619 exit1(td, W_EXITCODE(0, sig)); 620 return (0); 621} 622 623 624#ifdef COMPAT_43 625/* 626 * The dirty work is handled by kern_wait(). 627 */ 628int 629owait(struct thread *td, struct owait_args *uap __unused) 630{ 631 int error, status; 632 633 error = kern_wait(td, WAIT_ANY, &status, 0, NULL); 634 if (error == 0) 635 td->td_retval[1] = status; 636 return (error); 637} 638#endif /* COMPAT_43 */ 639 640/* 641 * The dirty work is handled by kern_wait(). 642 */ 643int 644wait4(struct thread *td, struct wait_args *uap) 645{ 646 struct rusage ru, *rup; 647 int error, status; 648 649 if (uap->rusage != NULL) 650 rup = &ru; 651 else 652 rup = NULL; 653 error = kern_wait(td, uap->pid, &status, uap->options, rup); 654 if (uap->status != NULL && error == 0) 655 error = copyout(&status, uap->status, sizeof(status)); 656 if (uap->rusage != NULL && error == 0) 657 error = copyout(&ru, uap->rusage, sizeof(struct rusage)); 658 return (error); 659} 660 661/* 662 * Reap the remains of a zombie process and optionally return status and 663 * rusage. Asserts and will release both the proctree_lock and the process 664 * lock as part of its work. 665 */ 666static void 667proc_reap(struct thread *td, struct proc *p, int *status, int options, 668 struct rusage *rusage) 669{ 670 struct proc *q, *t; 671 672 sx_assert(&proctree_lock, SA_XLOCKED); 673 PROC_LOCK_ASSERT(p, MA_OWNED); 674 PROC_SLOCK_ASSERT(p, MA_OWNED); 675 KASSERT(p->p_state == PRS_ZOMBIE, ("proc_reap: !PRS_ZOMBIE")); 676 677 q = td->td_proc; 678 if (rusage) { 679 *rusage = p->p_ru; 680 calcru(p, &rusage->ru_utime, &rusage->ru_stime); 681 } 682 PROC_SUNLOCK(p); 683 td->td_retval[0] = p->p_pid; 684 if (status) 685 *status = p->p_xstat; /* convert to int */ 686 if (options & WNOWAIT) { 687 /* 688 * Only poll, returning the status. Caller does not wish to 689 * release the proc struct just yet. 690 */ 691 PROC_UNLOCK(p); 692 sx_xunlock(&proctree_lock); 693 return; 694 } 695 696 PROC_LOCK(q); 697 sigqueue_take(p->p_ksi); 698 PROC_UNLOCK(q); 699 PROC_UNLOCK(p); 700 701 /* 702 * If we got the child via a ptrace 'attach', we need to give it back 703 * to the old parent. 704 */ 705 if (p->p_oppid && (t = pfind(p->p_oppid)) != NULL) { 706 PROC_LOCK(p); 707 p->p_oppid = 0; 708 proc_reparent(p, t); 709 PROC_UNLOCK(p); 710 pksignal(t, SIGCHLD, p->p_ksi); 711 wakeup(t); 712 cv_broadcast(&p->p_pwait); 713 PROC_UNLOCK(t); 714 sx_xunlock(&proctree_lock); 715 return; 716 } 717 718 /* 719 * Remove other references to this process to ensure we have an 720 * exclusive reference. 721 */ 722 sx_xlock(&allproc_lock); 723 LIST_REMOVE(p, p_list); /* off zombproc */ 724 sx_xunlock(&allproc_lock); 725 LIST_REMOVE(p, p_sibling); 726 leavepgrp(p); 727 sx_xunlock(&proctree_lock); 728 729 /* 730 * As a side effect of this lock, we know that all other writes to 731 * this proc are visible now, so no more locking is needed for p. 732 */ 733 PROC_LOCK(p); 734 p->p_xstat = 0; /* XXX: why? */ 735 PROC_UNLOCK(p); 736 PROC_LOCK(q); 737 ruadd(&q->p_stats->p_cru, &q->p_crux, &p->p_ru, &p->p_rux); 738 PROC_UNLOCK(q); 739 740 /* 741 * Decrement the count of procs running with this uid. 742 */ 743 (void)chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0); 744 745 /* 746 * Destroy resource accounting information associated with the process. 747 */ 748 racct_proc_exit(p); 749 PROC_LOCK(p->p_pptr); 750 racct_sub(p->p_pptr, RACCT_NPROC, 1); 751 PROC_UNLOCK(p->p_pptr); 752 753 /* 754 * Free credentials, arguments, and sigacts. 755 */ 756 crfree(p->p_ucred); 757 p->p_ucred = NULL; 758 pargs_drop(p->p_args); 759 p->p_args = NULL; 760 sigacts_free(p->p_sigacts); 761 p->p_sigacts = NULL; 762 763 /* 764 * Do any thread-system specific cleanups. 765 */ 766 thread_wait(p); 767 768 /* 769 * Give vm and machine-dependent layer a chance to free anything that 770 * cpu_exit couldn't release while still running in process context. 771 */ 772 vm_waitproc(p); 773#ifdef MAC 774 mac_proc_destroy(p); 775#endif 776 KASSERT(FIRST_THREAD_IN_PROC(p), 777 ("proc_reap: no residual thread!")); 778 uma_zfree(proc_zone, p); 779 sx_xlock(&allproc_lock); 780 nprocs--; 781 sx_xunlock(&allproc_lock); 782} 783 784int 785kern_wait(struct thread *td, pid_t pid, int *status, int options, 786 struct rusage *rusage) 787{ 788 struct proc *p, *q; 789 int error, nfound; 790 791 AUDIT_ARG_PID(pid); 792 AUDIT_ARG_VALUE(options); 793 794 q = td->td_proc; 795 if (pid == 0) { 796 PROC_LOCK(q); 797 pid = -q->p_pgid; 798 PROC_UNLOCK(q); 799 } 800 if (options &~ (WUNTRACED|WNOHANG|WCONTINUED|WNOWAIT|WLINUXCLONE)) 801 return (EINVAL); 802loop: 803 if (q->p_flag & P_STATCHILD) { 804 PROC_LOCK(q); 805 q->p_flag &= ~P_STATCHILD; 806 PROC_UNLOCK(q); 807 } 808 nfound = 0; 809 sx_xlock(&proctree_lock); 810 LIST_FOREACH(p, &q->p_children, p_sibling) { 811 PROC_LOCK(p); 812 if (pid != WAIT_ANY && 813 p->p_pid != pid && p->p_pgid != -pid) { 814 PROC_UNLOCK(p); 815 continue; 816 } 817 if (p_canwait(td, p)) { 818 PROC_UNLOCK(p); 819 continue; 820 } 821 822 /* 823 * This special case handles a kthread spawned by linux_clone 824 * (see linux_misc.c). The linux_wait4 and linux_waitpid 825 * functions need to be able to distinguish between waiting 826 * on a process and waiting on a thread. It is a thread if 827 * p_sigparent is not SIGCHLD, and the WLINUXCLONE option 828 * signifies we want to wait for threads and not processes. 829 */ 830 if ((p->p_sigparent != SIGCHLD) ^ 831 ((options & WLINUXCLONE) != 0)) { 832 PROC_UNLOCK(p); 833 continue; 834 } 835 836 nfound++; 837 PROC_SLOCK(p); 838 if (p->p_state == PRS_ZOMBIE) { 839 proc_reap(td, p, status, options, rusage); 840 return (0); 841 } 842 if ((p->p_flag & P_STOPPED_SIG) && 843 (p->p_suspcount == p->p_numthreads) && 844 (p->p_flag & P_WAITED) == 0 && 845 (p->p_flag & P_TRACED || options & WUNTRACED)) { 846 PROC_SUNLOCK(p); 847 p->p_flag |= P_WAITED; 848 sx_xunlock(&proctree_lock); 849 td->td_retval[0] = p->p_pid; 850 if (status) 851 *status = W_STOPCODE(p->p_xstat); 852 853 PROC_LOCK(q); 854 sigqueue_take(p->p_ksi); 855 PROC_UNLOCK(q); 856 PROC_UNLOCK(p); 857 858 return (0); 859 } 860 PROC_SUNLOCK(p); 861 if (options & WCONTINUED && (p->p_flag & P_CONTINUED)) { 862 sx_xunlock(&proctree_lock); 863 td->td_retval[0] = p->p_pid; 864 p->p_flag &= ~P_CONTINUED; 865 866 PROC_LOCK(q); 867 sigqueue_take(p->p_ksi); 868 PROC_UNLOCK(q); 869 PROC_UNLOCK(p); 870 871 if (status) 872 *status = SIGCONT; 873 return (0); 874 } 875 PROC_UNLOCK(p); 876 } 877 if (nfound == 0) { 878 sx_xunlock(&proctree_lock); 879 return (ECHILD); 880 } 881 if (options & WNOHANG) { 882 sx_xunlock(&proctree_lock); 883 td->td_retval[0] = 0; 884 return (0); 885 } 886 PROC_LOCK(q); 887 sx_xunlock(&proctree_lock); 888 if (q->p_flag & P_STATCHILD) { 889 q->p_flag &= ~P_STATCHILD; 890 error = 0; 891 } else 892 error = msleep(q, &q->p_mtx, PWAIT | PCATCH, "wait", 0); 893 PROC_UNLOCK(q); 894 if (error) 895 return (error); 896 goto loop; 897} 898 899/* 900 * Make process 'parent' the new parent of process 'child'. 901 * Must be called with an exclusive hold of proctree lock. 902 */ 903void 904proc_reparent(struct proc *child, struct proc *parent) 905{ 906 int locked; 907 908 sx_assert(&proctree_lock, SX_XLOCKED); 909 PROC_LOCK_ASSERT(child, MA_OWNED); 910 if (child->p_pptr == parent) 911 return; 912 913 locked = PROC_LOCKED(parent); 914 if (!locked) 915 PROC_LOCK(parent); 916 racct_add_force(parent, RACCT_NPROC, 1); 917 if (!locked) 918 PROC_UNLOCK(parent); 919 PROC_LOCK(child->p_pptr); 920 racct_sub(child->p_pptr, RACCT_NPROC, 1); 921 sigqueue_take(child->p_ksi); 922 PROC_UNLOCK(child->p_pptr); 923 LIST_REMOVE(child, p_sibling); 924 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); 925 child->p_pptr = parent; 926} 927