1 /* $NetBSD: kern_exit.c,v 1.168 2007/02/22 06:34:43 thorpej Exp $ */ 2 3 /*- 4 * Copyright (c) 1998, 1999, 2006, 2007 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, 9 * NASA Ames Research Center, and by Andrew Doran. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the NetBSD 22 * Foundation, Inc. and its contributors. 23 * 4. Neither the name of The NetBSD Foundation nor the names of its 24 * contributors may be used to endorse or promote products derived 25 * from this software without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 28 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 29 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 30 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 31 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 32 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 33 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 34 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 35 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 36 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 37 * POSSIBILITY OF SUCH DAMAGE. 38 */ 39 40 /* 41 * Copyright (c) 1982, 1986, 1989, 1991, 1993 42 * The Regents of the University of California. All rights reserved. 43 * (c) UNIX System Laboratories, Inc. 44 * All or some portions of this file are derived from material licensed 45 * to the University of California by American Telephone and Telegraph 46 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 47 * the permission of UNIX System Laboratories, Inc. 48 * 49 * Redistribution and use in source and binary forms, with or without 50 * modification, are permitted provided that the following conditions 51 * are met: 52 * 1. Redistributions of source code must retain the above copyright 53 * notice, this list of conditions and the following disclaimer. 54 * 2. Redistributions in binary form must reproduce the above copyright 55 * notice, this list of conditions and the following disclaimer in the 56 * documentation and/or other materials provided with the distribution. 57 * 3. Neither the name of the University nor the names of its contributors 58 * may be used to endorse or promote products derived from this software 59 * without specific prior written permission. 60 * 61 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 62 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 63 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 64 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 65 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 66 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 67 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 68 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 69 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 70 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 71 * SUCH DAMAGE. 72 * 73 * @(#)kern_exit.c 8.10 (Berkeley) 2/23/95 74 */ 75 76 #include <sys/cdefs.h> 77 __KERNEL_RCSID(0, "$NetBSD: kern_exit.c,v 1.168 2007/02/22 06:34:43 thorpej Exp $"); 78 79 #include "opt_ktrace.h" 80 #include "opt_perfctrs.h" 81 #include "opt_systrace.h" 82 #include "opt_sysv.h" 83 84 #include <sys/param.h> 85 #include <sys/systm.h> 86 #include <sys/ioctl.h> 87 #include <sys/tty.h> 88 #include <sys/time.h> 89 #include <sys/resource.h> 90 #include <sys/kernel.h> 91 #include <sys/proc.h> 92 #include <sys/buf.h> 93 #include <sys/wait.h> 94 #include <sys/file.h> 95 #include <sys/vnode.h> 96 #include <sys/syslog.h> 97 #include <sys/malloc.h> 98 #include <sys/pool.h> 99 #include <sys/resourcevar.h> 100 #if defined(PERFCTRS) 101 #include <sys/pmc.h> 102 #endif 103 #include <sys/ptrace.h> 104 #include <sys/acct.h> 105 #include <sys/filedesc.h> 106 #include <sys/ras.h> 107 #include <sys/signalvar.h> 108 #include <sys/sched.h> 109 #include <sys/mount.h> 110 #include <sys/syscallargs.h> 111 #include <sys/systrace.h> 112 #include <sys/kauth.h> 113 #include <sys/sleepq.h> 114 #include <sys/lockdebug.h> 115 #include <sys/ktrace.h> 116 117 #include <machine/cpu.h> 118 119 #include <uvm/uvm_extern.h> 120 121 #define DEBUG_EXIT 122 123 #ifdef DEBUG_EXIT 124 int debug_exit = 0; 125 #define DPRINTF(x) if (debug_exit) printf x 126 #else 127 #define DPRINTF(x) 128 #endif 129 130 /* 131 * Fill in the appropriate signal information, and signal the parent. 132 */ 133 static void 134 exit_psignal(struct proc *p, struct proc *pp, ksiginfo_t *ksi) 135 { 136 137 KSI_INIT(ksi); 138 if ((ksi->ksi_signo = P_EXITSIG(p)) == SIGCHLD) { 139 if (WIFSIGNALED(p->p_xstat)) { 140 if (WCOREDUMP(p->p_xstat)) 141 ksi->ksi_code = CLD_DUMPED; 142 else 143 ksi->ksi_code = CLD_KILLED; 144 } else { 145 ksi->ksi_code = CLD_EXITED; 146 } 147 } 148 /* 149 * We fill those in, even for non-SIGCHLD. 150 * It's safe to access p->p_cred unlocked here. 151 */ 152 ksi->ksi_pid = p->p_pid; 153 ksi->ksi_uid = kauth_cred_geteuid(p->p_cred); 154 ksi->ksi_status = p->p_xstat; 155 /* XXX: is this still valid? */ 156 ksi->ksi_utime = p->p_ru->ru_utime.tv_sec; 157 ksi->ksi_stime = p->p_ru->ru_stime.tv_sec; 158 } 159 160 /* 161 * exit -- 162 * Death of process. 163 */ 164 int 165 sys_exit(struct lwp *l, void *v, register_t *retval) 166 { 167 struct sys_exit_args /* { 168 syscallarg(int) rval; 169 } */ *uap = v; 170 struct proc *p = l->l_proc; 171 172 /* Don't call exit1() multiple times in the same process. */ 173 mutex_enter(&p->p_smutex); 174 if (p->p_sflag & PS_WEXIT) { 175 mutex_exit(&p->p_smutex); 176 lwp_exit(l); 177 } 178 179 /* exit1() will release the mutex. */ 180 exit1(l, W_EXITCODE(SCARG(uap, rval), 0)); 181 /* NOTREACHED */ 182 return (0); 183 } 184 185 /* 186 * Exit: deallocate address space and other resources, change proc state 187 * to zombie, and unlink proc from allproc and parent's lists. Save exit 188 * status and rusage for wait(). Check for child processes and orphan them. 189 * 190 * Must be called with p->p_smutex held. Does not return. 191 */ 192 void 193 exit1(struct lwp *l, int rv) 194 { 195 struct proc *p, *q, *nq; 196 int s; 197 ksiginfo_t ksi; 198 ksiginfoq_t kq; 199 int wakeinit; 200 201 p = l->l_proc; 202 203 LOCK_ASSERT(mutex_owned(&p->p_smutex)); 204 205 if (__predict_false(p == initproc)) 206 panic("init died (signal %d, exit %d)", 207 WTERMSIG(rv), WEXITSTATUS(rv)); 208 209 p->p_sflag |= PS_WEXIT; 210 211 /* 212 * Force all other LWPs to exit before we do. Only then can we 213 * begin to tear down the rest of the process state. 214 */ 215 if (p->p_nlwps > 1) 216 exit_lwps(l); 217 218 ksiginfo_queue_init(&kq); 219 220 /* 221 * If we have been asked to stop on exit, do so now. 222 */ 223 if (p->p_sflag & PS_STOPEXIT) { 224 KERNEL_UNLOCK_ALL(l, &l->l_biglocks); 225 sigclearall(p, &contsigmask, &kq); 226 p->p_waited = 0; 227 mb_write(); 228 p->p_stat = SSTOP; 229 lwp_lock(l); 230 p->p_nrlwps--; 231 l->l_stat = LSSTOP; 232 mutex_exit(&p->p_smutex); 233 mi_switch(l, NULL); 234 KERNEL_LOCK(l->l_biglocks, l); 235 } else 236 mutex_exit(&p->p_smutex); 237 238 /* 239 * Drain all remaining references that procfs, ptrace and others may 240 * have on the process. 241 */ 242 mutex_enter(&p->p_mutex); 243 proc_drainrefs(p); 244 mutex_exit(&p->p_mutex); 245 246 /* 247 * Bin any remaining signals and mark the process as dying so it will 248 * not be found for, e.g. signals. 249 */ 250 mutex_enter(&p->p_smutex); 251 sigfillset(&p->p_sigctx.ps_sigignore); 252 sigclearall(p, NULL, &kq); 253 p->p_stat = SDYING; 254 mutex_exit(&p->p_smutex); 255 ksiginfo_queue_drain(&kq); 256 257 DPRINTF(("exit1: %d.%d exiting.\n", p->p_pid, l->l_lid)); 258 259 #ifdef PGINPROF 260 vmsizmon(); 261 #endif 262 p->p_ru = pool_get(&rusage_pool, PR_WAITOK); 263 timers_free(p, TIMERS_ALL); 264 #if defined(__HAVE_RAS) 265 ras_purgeall(p); 266 #endif 267 268 /* 269 * Close open files, release open-file table and free signal 270 * actions. This may block! 271 */ 272 fdfree(l); 273 cwdfree(p->p_cwdi); 274 p->p_cwdi = NULL; 275 doexithooks(p); 276 sigactsfree(p->p_sigacts); 277 278 /* 279 * Write out accounting data. 280 */ 281 (void)acct_process(l); 282 283 #ifdef KTRACE 284 /* 285 * Release trace file. 286 */ 287 if (p->p_tracep != NULL) { 288 mutex_enter(&ktrace_mutex); 289 ktrderef(p); 290 mutex_exit(&ktrace_mutex); 291 } 292 #endif 293 #ifdef SYSTRACE 294 systrace_sys_exit(p); 295 #endif 296 297 /* 298 * If emulation has process exit hook, call it now. 299 * Set the exit status now so that the exit hook has 300 * an opportunity to tweak it (COMPAT_LINUX requires 301 * this for thread group emulation) 302 */ 303 p->p_xstat = rv; 304 if (p->p_emul->e_proc_exit) 305 (*p->p_emul->e_proc_exit)(p); 306 307 /* 308 * Finalize the last LWP's specificdata, as well as the 309 * specificdata for the proc itself. 310 */ 311 lwp_finispecific(l); 312 proc_finispecific(p); 313 314 /* Collect child u-areas. */ 315 uvm_uarea_drain(false); 316 317 /* 318 * Free the VM resources we're still holding on to. 319 * We must do this from a valid thread because doing 320 * so may block. This frees vmspace, which we don't 321 * need anymore. The only remaining lwp is the one 322 * we run at this moment, nothing runs in userland 323 * anymore. 324 */ 325 uvm_proc_exit(p); 326 327 /* 328 * Stop profiling. 329 */ 330 if ((p->p_stflag & PST_PROFIL) != 0) { 331 mutex_spin_enter(&p->p_stmutex); 332 stopprofclock(p); 333 mutex_spin_exit(&p->p_stmutex); 334 } 335 336 /* 337 * If parent is waiting for us to exit or exec, P_PPWAIT is set; we 338 * wake up the parent early to avoid deadlock. We can do this once 339 * the VM resources are released. 340 */ 341 rw_enter(&proclist_lock, RW_WRITER); 342 343 mutex_enter(&p->p_smutex); 344 if (p->p_sflag & PS_PPWAIT) { 345 p->p_sflag &= ~PS_PPWAIT; 346 cv_wakeup(&p->p_pptr->p_waitcv); /* XXXSMP */ 347 } 348 mutex_exit(&p->p_smutex); 349 350 if (SESS_LEADER(p)) { 351 struct vnode *vprele = NULL, *vprevoke = NULL; 352 struct session *sp = p->p_session; 353 struct tty *tp; 354 355 if (sp->s_ttyvp) { 356 /* 357 * Controlling process. 358 * Signal foreground pgrp, 359 * drain controlling terminal 360 * and revoke access to controlling terminal. 361 */ 362 tp = sp->s_ttyp; 363 s = spltty(); 364 TTY_LOCK(tp); 365 if (tp->t_session == sp) { 366 if (tp->t_pgrp) { 367 mutex_enter(&proclist_mutex); 368 pgsignal(tp->t_pgrp, SIGHUP, 1); 369 mutex_exit(&proclist_mutex); 370 } 371 /* we can't guarantee the revoke will do this */ 372 tp->t_pgrp = NULL; 373 tp->t_session = NULL; 374 TTY_UNLOCK(tp); 375 splx(s); 376 SESSRELE(sp); 377 rw_exit(&proclist_lock); 378 (void) ttywait(tp); 379 rw_enter(&proclist_lock, RW_WRITER); 380 381 /* 382 * The tty could have been revoked 383 * if we blocked. 384 */ 385 vprevoke = sp->s_ttyvp; 386 } else { 387 TTY_UNLOCK(tp); 388 splx(s); 389 } 390 vprele = sp->s_ttyvp; 391 sp->s_ttyvp = NULL; 392 /* 393 * s_ttyp is not zero'd; we use this to indicate 394 * that the session once had a controlling terminal. 395 * (for logging and informational purposes) 396 */ 397 } 398 sp->s_leader = NULL; 399 400 if (vprevoke != NULL || vprele != NULL) { 401 rw_exit(&proclist_lock); 402 if (vprevoke != NULL) 403 VOP_REVOKE(vprevoke, REVOKEALL); 404 if (vprele != NULL) 405 vrele(vprele); 406 rw_enter(&proclist_lock, RW_WRITER); 407 } 408 } 409 mutex_enter(&proclist_mutex); 410 fixjobc(p, p->p_pgrp, 0); 411 mutex_exit(&proclist_mutex); 412 413 /* 414 * Notify interested parties of our demise. 415 */ 416 KNOTE(&p->p_klist, NOTE_EXIT); 417 418 #if PERFCTRS 419 /* 420 * Save final PMC information in parent process & clean up. 421 */ 422 if (PMC_ENABLED(p)) { 423 pmc_save_context(p); 424 pmc_accumulate(p->p_pptr, p); 425 pmc_process_exit(p); 426 } 427 #endif 428 429 /* 430 * Reset p_opptr pointer of all former children which got 431 * traced by another process and were reparented. We reset 432 * it to NULL here; the trace detach code then reparents 433 * the child to initproc. We only check allproc list, since 434 * eventual former children on zombproc list won't reference 435 * p_opptr anymore. 436 */ 437 if (p->p_slflag & PSL_CHTRACED) { 438 PROCLIST_FOREACH(q, &allproc) { 439 if (q->p_opptr == p) 440 q->p_opptr = NULL; 441 } 442 } 443 444 /* 445 * Give orphaned children to init(8). 446 */ 447 q = LIST_FIRST(&p->p_children); 448 wakeinit = (q != NULL); 449 for (; q != NULL; q = nq) { 450 nq = LIST_NEXT(q, p_sibling); 451 452 /* 453 * Traced processes are killed since their existence 454 * means someone is screwing up. Since we reset the 455 * trace flags, the logic in sys_wait4() would not be 456 * triggered to reparent the process to its 457 * original parent, so we must do this here. 458 */ 459 if (q->p_slflag & PSL_TRACED) { 460 mutex_enter(&p->p_smutex); 461 q->p_slflag &= ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL); 462 mutex_exit(&p->p_smutex); 463 if (q->p_opptr != q->p_pptr) { 464 struct proc *t = q->p_opptr; 465 proc_reparent(q, t ? t : initproc); 466 q->p_opptr = NULL; 467 } else 468 proc_reparent(q, initproc); 469 killproc(q, "orphaned traced process"); 470 } else 471 proc_reparent(q, initproc); 472 } 473 474 /* 475 * Move proc from allproc to zombproc, it's now nearly ready to be 476 * collected by parent. 477 */ 478 mutex_enter(&proclist_mutex); 479 LIST_REMOVE(l, l_list); 480 LIST_REMOVE(p, p_list); 481 LIST_INSERT_HEAD(&zombproc, p, p_list); 482 483 /* 484 * Mark the process as dead. We must do this before we signal 485 * the parent. 486 */ 487 p->p_stat = SDEAD; 488 489 /* Put in front of parent's sibling list for parent to collect it */ 490 q = p->p_pptr; 491 q->p_nstopchild++; 492 if (LIST_FIRST(&q->p_children) != p) { 493 /* Put child where it can be found quickly */ 494 LIST_REMOVE(p, p_sibling); 495 LIST_INSERT_HEAD(&q->p_children, p, p_sibling); 496 } 497 mutex_exit(&proclist_mutex); 498 499 /* 500 * Notify parent that we're gone. If parent has the P_NOCLDWAIT 501 * flag set, notify init instead (and hope it will handle 502 * this situation). 503 */ 504 mutex_enter(&q->p_mutex); 505 if (q->p_flag & (PK_NOCLDWAIT|PK_CLDSIGIGN)) { 506 proc_reparent(p, initproc); 507 wakeinit = 1; 508 509 /* 510 * If this was the last child of our parent, notify 511 * parent, so in case he was wait(2)ing, he will 512 * continue. 513 */ 514 if (LIST_FIRST(&q->p_children) == NULL) 515 cv_wakeup(&q->p_waitcv); /* XXXSMP */ 516 } 517 mutex_exit(&q->p_mutex); 518 519 /* Reload parent pointer, since p may have been reparented above */ 520 q = p->p_pptr; 521 522 if ((p->p_slflag & PSL_FSTRACE) == 0 && p->p_exitsig != 0) { 523 exit_psignal(p, q, &ksi); 524 mutex_enter(&proclist_mutex); 525 kpsignal(q, &ksi, NULL); 526 mutex_exit(&proclist_mutex); 527 } 528 529 /* 530 * Save final rusage info, adding in child rusage info and self 531 * times. It's OK to call caclru() unlocked here. 532 */ 533 *p->p_ru = p->p_stats->p_ru; 534 calcru(p, &p->p_ru->ru_utime, &p->p_ru->ru_stime, NULL, NULL); 535 ruadd(p->p_ru, &p->p_stats->p_cru); 536 537 if (wakeinit) 538 cv_wakeup(&initproc->p_waitcv); /* XXXSMP */ 539 540 /* 541 * Remaining lwp resources will be freed in lwp_exit2() once we've 542 * switch to idle context; at that point, we will be marked as a 543 * full blown zombie. 544 * 545 * XXXSMP disable preemption. 546 */ 547 mutex_enter(&p->p_smutex); 548 lwp_drainrefs(l); 549 lwp_lock(l); 550 l->l_prflag &= ~LPR_DETACHED; 551 l->l_stat = LSZOMB; 552 lwp_unlock(l); 553 KASSERT(curlwp == l); 554 KASSERT(p->p_nrlwps == 1); 555 KASSERT(p->p_nlwps == 1); 556 p->p_stat = SZOMB; 557 p->p_nrlwps--; 558 p->p_nzlwps++; 559 p->p_ndlwps = 0; 560 mutex_exit(&p->p_smutex); 561 562 /* 563 * Signal the parent to collect us, and drop the proclist lock. 564 */ 565 rw_exit(&proclist_lock); 566 567 /* Verify that we hold no locks other than the kernel lock. */ 568 #ifdef MULTIPROCESSOR 569 LOCKDEBUG_BARRIER(&kernel_lock, 0); 570 #else 571 LOCKDEBUG_BARRIER(NULL, 0); 572 #endif 573 574 /* 575 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 576 */ 577 578 /* 579 * Give machine-dependent code a chance to free any MD LWP 580 * resources. This must be done before uvm_lwp_exit(), in 581 * case these resources are in the PCB. 582 */ 583 #ifndef __NO_CPU_LWP_FREE 584 cpu_lwp_free(l, 1); 585 #endif 586 pmap_deactivate(l); 587 588 /* This process no longer needs to hold the kernel lock. */ 589 #ifdef notyet 590 /* XXXSMP hold in lwp_userret() */ 591 KERNEL_UNLOCK_LAST(l); 592 #else 593 KERNEL_UNLOCK_ALL(l, NULL); 594 #endif 595 596 /* 597 * Finally, call machine-dependent code to switch to a new 598 * context (possibly the idle context). Once we are no longer 599 * using the dead lwp's stack, lwp_exit2() will be called. 600 * 601 * Note that cpu_exit() will end with a call equivalent to 602 * cpu_switch(), finishing our execution (pun intended). 603 */ 604 uvmexp.swtch++; /* XXXSMP unlocked */ 605 cv_wakeup(&p->p_pptr->p_waitcv); /* XXXSMP */ 606 cpu_exit(l); 607 } 608 609 void 610 exit_lwps(struct lwp *l) 611 { 612 struct proc *p; 613 struct lwp *l2; 614 int error; 615 lwpid_t waited; 616 #if defined(MULTIPROCESSOR) 617 int nlocks; 618 #endif 619 620 KERNEL_UNLOCK_ALL(l, &nlocks); 621 622 p = l->l_proc; 623 624 retry: 625 /* 626 * Interrupt LWPs in interruptable sleep, unsuspend suspended 627 * LWPs and then wait for everyone else to finish. 628 */ 629 LIST_FOREACH(l2, &p->p_lwps, l_sibling) { 630 if (l2 == l) 631 continue; 632 lwp_lock(l2); 633 l2->l_flag |= LW_WEXIT; 634 if ((l2->l_stat == LSSLEEP && (l2->l_flag & LW_SINTR)) || 635 l2->l_stat == LSSUSPENDED || l2->l_stat == LSSTOP) { 636 /* setrunnable() will release the lock. */ 637 setrunnable(l2); 638 DPRINTF(("exit_lwps: Made %d.%d runnable\n", 639 p->p_pid, l2->l_lid)); 640 continue; 641 } 642 lwp_unlock(l2); 643 } 644 while (p->p_nlwps > 1) { 645 DPRINTF(("exit_lwps: waiting for %d LWPs (%d zombies)\n", 646 p->p_nlwps, p->p_nzlwps)); 647 error = lwp_wait1(l, 0, &waited, LWPWAIT_EXITCONTROL); 648 if (p->p_nlwps == 1) 649 break; 650 if (error == EDEADLK) { 651 /* 652 * LWPs can get suspended/slept behind us. 653 * (eg. sa_setwoken) 654 * kick them again and retry. 655 */ 656 goto retry; 657 } 658 if (error) 659 panic("exit_lwps: lwp_wait1 failed with error %d", 660 error); 661 DPRINTF(("exit_lwps: Got LWP %d from lwp_wait1()\n", waited)); 662 } 663 664 KERNEL_LOCK(nlocks, l); 665 } 666 667 int 668 sys_wait4(struct lwp *l, void *v, register_t *retval) 669 { 670 struct sys_wait4_args /* { 671 syscallarg(int) pid; 672 syscallarg(int *) status; 673 syscallarg(int) options; 674 syscallarg(struct rusage *) rusage; 675 } */ *uap = v; 676 struct proc *child, *parent; 677 int status, error; 678 struct rusage ru; 679 680 parent = l->l_proc; 681 682 if (SCARG(uap, pid) == 0) 683 SCARG(uap, pid) = -parent->p_pgid; 684 if (SCARG(uap, options) & ~(WUNTRACED|WNOHANG|WALTSIG|WALLSIG)) 685 return (EINVAL); 686 687 rw_enter(&proclist_lock, RW_WRITER); 688 689 error = find_stopped_child(parent, SCARG(uap,pid), SCARG(uap,options), 690 &child, &status); 691 if (error != 0) { 692 rw_exit(&proclist_lock); 693 return error; 694 } 695 if (child == NULL) { 696 rw_exit(&proclist_lock); 697 *retval = 0; 698 return 0; 699 } 700 701 retval[0] = child->p_pid; 702 703 if (P_ZOMBIE(child)) { 704 KERNEL_LOCK(1, l); /* XXXSMP */ 705 /* proc_free() will release the proclist_lock. */ 706 proc_free(child, (SCARG(uap, rusage) == NULL ? NULL : &ru)); 707 KERNEL_UNLOCK_ONE(l); /* XXXSMP */ 708 709 if (SCARG(uap, rusage)) 710 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru)); 711 if (error == 0 && SCARG(uap, status)) 712 error = copyout(&status, SCARG(uap, status), 713 sizeof(status)); 714 715 return error; 716 } 717 718 rw_exit(&proclist_lock); 719 720 /* Child state must have been SSTOP. */ 721 if (SCARG(uap, status)) { 722 status = W_STOPCODE(status); 723 return copyout(&status, SCARG(uap, status), sizeof(status)); 724 } 725 726 return 0; 727 } 728 729 /* 730 * Scan list of child processes for a child process that has stopped or 731 * exited. Used by sys_wait4 and 'compat' equivalents. 732 * 733 * Must be called with the proclist_lock write held, and may release 734 * while waiting. 735 */ 736 int 737 find_stopped_child(struct proc *parent, pid_t pid, int options, 738 struct proc **child_p, int *status_p) 739 { 740 struct proc *child, *dead; 741 int error; 742 743 LOCK_ASSERT(rw_write_held(&proclist_lock)); 744 745 for (;;) { 746 error = ECHILD; 747 dead = NULL; 748 749 mutex_enter(&proclist_mutex); 750 LIST_FOREACH(child, &parent->p_children, p_sibling) { 751 if (pid >= 0) { 752 if (child->p_pid != pid) { 753 child = p_find(pid, PFIND_ZOMBIE | 754 PFIND_LOCKED); 755 if (child == NULL || 756 child->p_pptr != parent) { 757 child = NULL; 758 break; 759 } 760 } 761 } else if (pid != WAIT_ANY && child->p_pgid != -pid) { 762 /* Child not in correct pgrp */ 763 continue; 764 } 765 766 /* 767 * Wait for processes with p_exitsig != SIGCHLD 768 * processes only if WALTSIG is set; wait for 769 * processes with p_exitsig == SIGCHLD only 770 * if WALTSIG is clear. 771 */ 772 if (((options & WALLSIG) == 0) && 773 (options & WALTSIG ? child->p_exitsig == SIGCHLD 774 : P_EXITSIG(child) != SIGCHLD)){ 775 if (child->p_pid == pid) { 776 child = NULL; 777 break; 778 } 779 continue; 780 } 781 782 error = 0; 783 if ((options & WNOZOMBIE) == 0) { 784 if (child->p_stat == SZOMB) 785 break; 786 if (child->p_stat == SDEAD) { 787 /* 788 * We may occasionally arrive here 789 * after receiving a signal, but 790 * immediatley before the child 791 * process is zombified. The wait 792 * will be short, so avoid returning 793 * to userspace. 794 */ 795 dead = child; 796 } 797 } 798 799 if (child->p_stat == SSTOP && 800 child->p_waited == 0 && 801 (child->p_slflag & PSL_TRACED || 802 options & WUNTRACED)) { 803 if ((options & WNOWAIT) == 0) { 804 child->p_waited = 1; 805 parent->p_nstopchild--; 806 } 807 break; 808 } 809 if (parent->p_nstopchild == 0 || child->p_pid == pid) { 810 child = NULL; 811 break; 812 } 813 } 814 815 if (child != NULL || error != 0 || 816 ((options & WNOHANG) != 0 && dead == NULL)) { 817 if (child != NULL) 818 *status_p = child->p_xstat; 819 mutex_exit(&proclist_mutex); 820 *child_p = child; 821 return error; 822 } 823 824 /* 825 * Wait for another child process to stop. 826 */ 827 rw_exit(&proclist_lock); 828 error = cv_wait_sig(&parent->p_waitcv, &proclist_mutex); 829 mutex_exit(&proclist_mutex); 830 rw_enter(&proclist_lock, RW_WRITER); 831 832 if (error != 0) 833 return error; 834 } 835 } 836 837 /* 838 * Free a process after parent has taken all the state info. Must be called 839 * with the proclist lock write held, and will release before returning. 840 * 841 * *ru is returned to the caller, and must be freed by the caller. 842 */ 843 void 844 proc_free(struct proc *p, struct rusage *caller_ru) 845 { 846 struct plimit *plim; 847 struct pstats *pstats; 848 struct rusage *ru; 849 struct proc *parent; 850 struct lwp *l; 851 ksiginfo_t ksi; 852 kauth_cred_t cred; 853 struct vnode *vp; 854 uid_t uid; 855 856 LOCK_ASSERT(rw_write_held(&proclist_lock)); 857 858 KASSERT(p->p_nlwps == 1); 859 KASSERT(p->p_nzlwps == 1); 860 KASSERT(p->p_nrlwps == 0); 861 KASSERT(p->p_stat == SZOMB); 862 863 if (caller_ru != NULL) 864 memcpy(caller_ru, p->p_ru, sizeof(*caller_ru)); 865 866 /* 867 * If we got the child via ptrace(2) or procfs, and 868 * the parent is different (meaning the process was 869 * attached, rather than run as a child), then we need 870 * to give it back to the old parent, and send the 871 * parent the exit signal. The rest of the cleanup 872 * will be done when the old parent waits on the child. 873 */ 874 if ((p->p_slflag & PSL_TRACED) != 0) { 875 parent = p->p_pptr; 876 if (p->p_opptr != parent){ 877 mutex_enter(&p->p_smutex); 878 p->p_slflag &= ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL); 879 mutex_exit(&p->p_smutex); 880 parent = p->p_opptr; 881 if (parent == NULL) 882 parent = initproc; 883 proc_reparent(p, parent); 884 p->p_opptr = NULL; 885 if (p->p_exitsig != 0) { 886 exit_psignal(p, parent, &ksi); 887 mutex_enter(&proclist_mutex); 888 kpsignal(parent, &ksi, NULL); 889 mutex_exit(&proclist_mutex); 890 } 891 cv_wakeup(&parent->p_waitcv); /* XXXSMP */ 892 rw_exit(&proclist_lock); 893 return; 894 } 895 } 896 897 /* 898 * Finally finished with old proc entry. Unlink it from its process 899 * group. 900 */ 901 leavepgrp(p); 902 903 parent = p->p_pptr; 904 scheduler_wait_hook(parent, p); 905 ruadd(&parent->p_stats->p_cru, p->p_ru); 906 p->p_xstat = 0; 907 908 /* 909 * At this point we are going to start freeing the final resources. 910 * If anyone tries to access the proc structure after here they will 911 * get a shock - bits are missing. Attempt to make it hard! We 912 * don't bother with any further locking past this point. 913 */ 914 mutex_enter(&proclist_mutex); 915 p->p_stat = SIDL; /* not even a zombie any more */ 916 LIST_REMOVE(p, p_list); /* off zombproc */ 917 parent = p->p_pptr; 918 p->p_pptr->p_nstopchild--; 919 mutex_exit(&proclist_mutex); 920 LIST_REMOVE(p, p_sibling); 921 922 uid = kauth_cred_getuid(p->p_cred); 923 vp = p->p_textvp; 924 cred = p->p_cred; 925 ru = p->p_ru; 926 927 l = LIST_FIRST(&p->p_lwps); 928 929 #ifdef MULTIPROCESSOR 930 /* 931 * If the last remaining LWP is still on the CPU (unlikely), then 932 * spin until it has switched away. We need to release all locks 933 * to avoid deadlock against interrupt handlers on the target CPU. 934 */ 935 if (l->l_cpu->ci_curlwp == l) { 936 int count; 937 rw_exit(&proclist_lock); 938 KERNEL_UNLOCK_ALL(l, &count); 939 while (l->l_cpu->ci_curlwp == l) 940 SPINLOCK_BACKOFF_HOOK; 941 KERNEL_LOCK(count, l); 942 rw_enter(&proclist_lock, RW_WRITER); 943 } 944 #endif 945 946 mutex_destroy(&p->p_rasmutex); 947 mutex_destroy(&p->p_mutex); 948 mutex_destroy(&p->p_stmutex); 949 mutex_destroy(&p->p_smutex); 950 cv_destroy(&p->p_waitcv); 951 cv_destroy(&p->p_lwpcv); 952 cv_destroy(&p->p_refcv); 953 954 /* 955 * Delay release until after dropping the proclist lock. 956 */ 957 plim = p->p_limit; 958 pstats = p->p_stats; 959 960 /* 961 * Free the proc structure and let pid be reallocated. This will 962 * release the proclist_lock. 963 */ 964 proc_free_mem(p); 965 966 /* 967 * Decrement the count of procs running with this uid. 968 */ 969 (void)chgproccnt(uid, -1); 970 971 /* 972 * Release substructures. 973 */ 974 limfree(plim); 975 pstatsfree(pstats); 976 kauth_cred_free(cred); 977 kauth_cred_free(l->l_cred); 978 979 /* 980 * Release reference to text vnode 981 */ 982 if (vp) 983 vrele(vp); 984 985 /* 986 * Free the last LWP's resources. 987 */ 988 lwp_free(l, 0, 1); 989 990 /* 991 * Collect child u-areas. 992 */ 993 uvm_uarea_drain(false); 994 pool_put(&rusage_pool, ru); 995 } 996 997 /* 998 * make process 'parent' the new parent of process 'child'. 999 * 1000 * Must be called with proclist_lock write locked held. 1001 */ 1002 void 1003 proc_reparent(struct proc *child, struct proc *parent) 1004 { 1005 1006 LOCK_ASSERT(rw_write_held(&proclist_lock)); 1007 1008 if (child->p_pptr == parent) 1009 return; 1010 1011 mutex_enter(&proclist_mutex); 1012 if (child->p_stat == SZOMB || 1013 (child->p_stat == SSTOP && !child->p_waited)) { 1014 child->p_pptr->p_nstopchild--; 1015 parent->p_nstopchild++; 1016 } 1017 mutex_exit(&proclist_mutex); 1018 if (parent == initproc) 1019 child->p_exitsig = SIGCHLD; 1020 1021 LIST_REMOVE(child, p_sibling); 1022 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); 1023 child->p_pptr = parent; 1024 } 1025