1 /* $OpenBSD: kern_exit.c,v 1.118 2012/08/02 03:18:48 guenther Exp $ */ 2 /* $NetBSD: kern_exit.c,v 1.39 1996/04/22 01:38:25 christos Exp $ */ 3 4 /* 5 * Copyright (c) 1982, 1986, 1989, 1991, 1993 6 * The Regents of the University of California. All rights reserved. 7 * (c) UNIX System Laboratories, Inc. 8 * All or some portions of this file are derived from material licensed 9 * to the University of California by American Telephone and Telegraph 10 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 11 * the permission of UNIX System Laboratories, Inc. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * @(#)kern_exit.c 8.7 (Berkeley) 2/12/94 38 */ 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/ioctl.h> 43 #include <sys/proc.h> 44 #include <sys/tty.h> 45 #include <sys/time.h> 46 #include <sys/resource.h> 47 #include <sys/kernel.h> 48 #include <sys/buf.h> 49 #include <sys/wait.h> 50 #include <sys/file.h> 51 #include <sys/vnode.h> 52 #include <sys/syslog.h> 53 #include <sys/malloc.h> 54 #include <sys/resourcevar.h> 55 #include <sys/ptrace.h> 56 #include <sys/acct.h> 57 #include <sys/filedesc.h> 58 #include <sys/signalvar.h> 59 #include <sys/sched.h> 60 #include <sys/ktrace.h> 61 #include <sys/pool.h> 62 #include <sys/mutex.h> 63 #ifdef SYSVSEM 64 #include <sys/sem.h> 65 #endif 66 67 #include "systrace.h" 68 #include <dev/systrace.h> 69 70 #include <sys/mount.h> 71 #include <sys/syscallargs.h> 72 73 #include <machine/cpu.h> 74 75 #include <uvm/uvm_extern.h> 76 77 /* 78 * exit -- 79 * Death of process. 80 */ 81 int 82 sys_exit(struct proc *p, void *v, register_t *retval) 83 { 84 struct sys_exit_args /* { 85 syscallarg(int) rval; 86 } */ *uap = v; 87 88 exit1(p, W_EXITCODE(SCARG(uap, rval), 0), EXIT_NORMAL); 89 /* NOTREACHED */ 90 return (0); 91 } 92 93 int 94 sys___threxit(struct proc *p, void *v, register_t *retval) 95 { 96 struct sys___threxit_args /* { 97 syscallarg(pid_t *) notdead; 98 } */ *uap = v; 99 100 if (!rthreads_enabled) 101 return (EINVAL); 102 103 if (SCARG(uap, notdead) != NULL) { 104 pid_t zero = 0; 105 if (copyout(&zero, SCARG(uap, notdead), sizeof(zero))) { 106 psignal(p, SIGSEGV); 107 } 108 } 109 exit1(p, 0, EXIT_THREAD); 110 111 return (0); 112 } 113 114 /* 115 * Exit: deallocate address space and other resources, change proc state 116 * to zombie, and unlink proc from allproc and parent's lists. Save exit 117 * status and rusage for wait(). Check for child processes and orphan them. 118 */ 119 void 120 exit1(struct proc *p, int rv, int flags) 121 { 122 struct process *pr, *qr, *nqr; 123 struct rusage *rup; 124 125 if (p->p_pid == 1) 126 panic("init died (signal %d, exit %d)", 127 WTERMSIG(rv), WEXITSTATUS(rv)); 128 129 atomic_setbits_int(&p->p_flag, P_WEXIT); 130 131 pr = p->p_p; 132 133 /* single-threaded? */ 134 if (TAILQ_FIRST(&pr->ps_threads) == p && 135 TAILQ_NEXT(p, p_thr_link) == NULL) 136 flags = EXIT_NORMAL; 137 else { 138 /* nope, multi-threaded */ 139 if (flags == EXIT_NORMAL) 140 single_thread_set(p, SINGLE_EXIT, 0); 141 else if (flags == EXIT_THREAD) 142 single_thread_check(p, 0); 143 } 144 145 if (flags == EXIT_NORMAL) { 146 atomic_setbits_int(&pr->ps_flags, PS_EXITING); 147 pr->ps_mainproc->p_xstat = rv; 148 149 /* 150 * If parent is waiting for us to exit or exec, PS_PPWAIT 151 * is set; we wake up the parent early to avoid deadlock. 152 */ 153 if (pr->ps_flags & PS_PPWAIT) { 154 atomic_clearbits_int(&pr->ps_flags, PS_PPWAIT); 155 atomic_clearbits_int(&pr->ps_pptr->ps_flags, 156 PS_ISPWAIT); 157 wakeup(pr->ps_pptr); 158 } 159 } 160 161 /* unlink ourselves from the active threads */ 162 TAILQ_REMOVE(&pr->ps_threads, p, p_thr_link); 163 if ((p->p_flag & P_THREAD) == 0) { 164 /* main thread gotta wait because it has the pid, et al */ 165 while (! TAILQ_EMPTY(&pr->ps_threads)) 166 tsleep(&pr->ps_threads, PUSER, "thrdeath", 0); 167 if (pr->ps_flags & PS_PROFIL) 168 stopprofclock(pr); 169 } else if (TAILQ_EMPTY(&pr->ps_threads)) 170 wakeup(&pr->ps_threads); 171 172 rup = pr->ps_ru; 173 if (rup == NULL) { 174 rup = pool_get(&rusage_pool, PR_WAITOK | PR_ZERO); 175 176 if (pr->ps_ru == NULL) 177 pr->ps_ru = rup; 178 else { 179 pool_put(&rusage_pool, rup); 180 rup = pr->ps_ru; 181 } 182 } 183 p->p_siglist = 0; 184 185 /* 186 * Close open files and release open-file table. 187 */ 188 fdfree(p); 189 190 if ((p->p_flag & P_THREAD) == 0) { 191 timeout_del(&pr->ps_realit_to); 192 timeout_del(&pr->ps_virt_to); 193 timeout_del(&pr->ps_prof_to); 194 #ifdef SYSVSEM 195 semexit(pr); 196 #endif 197 if (SESS_LEADER(pr)) { 198 struct session *sp = pr->ps_session; 199 200 if (sp->s_ttyvp) { 201 /* 202 * Controlling process. 203 * Signal foreground pgrp, 204 * drain controlling terminal 205 * and revoke access to controlling terminal. 206 */ 207 if (sp->s_ttyp->t_session == sp) { 208 if (sp->s_ttyp->t_pgrp) 209 pgsignal(sp->s_ttyp->t_pgrp, 210 SIGHUP, 1); 211 (void) ttywait(sp->s_ttyp); 212 /* 213 * The tty could have been revoked 214 * if we blocked. 215 */ 216 if (sp->s_ttyvp) 217 VOP_REVOKE(sp->s_ttyvp, 218 REVOKEALL); 219 } 220 if (sp->s_ttyvp) 221 vrele(sp->s_ttyvp); 222 sp->s_ttyvp = NULL; 223 /* 224 * s_ttyp is not zero'd; we use this to 225 * indicate that the session once had a 226 * controlling terminal. (for logging and 227 * informational purposes) 228 */ 229 } 230 sp->s_leader = NULL; 231 } 232 fixjobc(pr, pr->ps_pgrp, 0); 233 234 #ifdef ACCOUNTING 235 (void)acct_process(p); 236 #endif 237 238 #ifdef KTRACE 239 /* release trace file */ 240 if (pr->ps_tracevp) 241 ktrcleartrace(pr); 242 #endif 243 } 244 245 #if NSYSTRACE > 0 246 if (ISSET(p->p_flag, P_SYSTRACE)) 247 systrace_exit(p); 248 #endif 249 250 /* 251 * If emulation has process exit hook, call it now. 252 */ 253 if (p->p_emul->e_proc_exit) 254 (*p->p_emul->e_proc_exit)(p); 255 256 /* 257 * Remove proc from pidhash chain so looking it up won't 258 * work. Move it from allproc to zombproc, but do not yet 259 * wake up the reaper. We will put the proc on the 260 * deadproc list later (using the p_hash member), and 261 * wake up the reaper when we do. 262 */ 263 /* 264 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 265 */ 266 p->p_stat = SDEAD; 267 268 LIST_REMOVE(p, p_hash); 269 LIST_REMOVE(p, p_list); 270 LIST_INSERT_HEAD(&zombproc, p, p_list); 271 272 /* 273 * Give orphaned children to init(8). 274 */ 275 if ((p->p_flag & P_THREAD) == 0) { 276 qr = LIST_FIRST(&pr->ps_children); 277 if (qr) /* only need this if any child is S_ZOMB */ 278 wakeup(initproc->p_p); 279 for (; qr != 0; qr = nqr) { 280 nqr = LIST_NEXT(qr, ps_sibling); 281 proc_reparent(qr, initproc->p_p); 282 /* 283 * Traced processes are killed 284 * since their existence means someone is screwing up. 285 */ 286 if (qr->ps_flags & PS_TRACED) { 287 atomic_clearbits_int(&qr->ps_flags, PS_TRACED); 288 /* 289 * If single threading is active, 290 * direct the signal to the active 291 * thread to avoid deadlock. 292 */ 293 if (qr->ps_single) 294 ptsignal(qr->ps_single, SIGKILL, 295 STHREAD); 296 else 297 prsignal(qr, SIGKILL); 298 } 299 } 300 } 301 302 303 /* add thread's accumulated rusage into the process's total */ 304 ruadd(rup, &p->p_ru); 305 306 /* 307 * clear %cpu usage during swap 308 */ 309 p->p_pctcpu = 0; 310 311 if ((p->p_flag & P_THREAD) == 0) { 312 /* 313 * Final thread has died, so add on our children's rusage 314 * and calculate the total times 315 */ 316 calcru(&pr->ps_tu, &rup->ru_utime, &rup->ru_stime, NULL); 317 ruadd(rup, &pr->ps_cru); 318 319 /* notify interested parties of our demise and clean up */ 320 knote_processexit(pr); 321 322 /* 323 * Notify parent that we're gone. If we have P_NOZOMBIE 324 * or parent has the SAS_NOCLDWAIT flag set, notify process 1 325 * instead (and hope it will handle this situation). 326 */ 327 if ((p->p_flag & P_NOZOMBIE) || 328 (pr->ps_pptr->ps_mainproc->p_sigacts->ps_flags & 329 SAS_NOCLDWAIT)) { 330 struct process *ppr = pr->ps_pptr; 331 proc_reparent(pr, initproc->p_p); 332 /* 333 * If this was the last child of our parent, notify 334 * parent, so in case he was wait(2)ing, he will 335 * continue. 336 */ 337 if (LIST_EMPTY(&ppr->ps_children)) 338 wakeup(ppr); 339 } 340 } 341 342 /* 343 * Release the process's signal state. 344 */ 345 sigactsfree(p); 346 347 /* 348 * Other substructures are freed from reaper and wait(). 349 */ 350 351 /* 352 * Finally, call machine-dependent code to switch to a new 353 * context (possibly the idle context). Once we are no longer 354 * using the dead process's vmspace and stack, exit2() will be 355 * called to schedule those resources to be released by the 356 * reaper thread. 357 * 358 * Note that cpu_exit() will end with a call equivalent to 359 * cpu_switch(), finishing our execution (pun intended). 360 */ 361 uvmexp.swtch++; 362 cpu_exit(p); 363 panic("cpu_exit returned"); 364 } 365 366 /* 367 * Locking of this proclist is special; it's accessed in a 368 * critical section of process exit, and thus locking it can't 369 * modify interrupt state. We use a simple spin lock for this 370 * proclist. Processes on this proclist are also on zombproc; 371 * we use the p_hash member to linkup to deadproc. 372 */ 373 struct mutex deadproc_mutex = MUTEX_INITIALIZER(IPL_NONE); 374 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 375 376 /* 377 * We are called from cpu_exit() once it is safe to schedule the 378 * dead process's resources to be freed. 379 * 380 * NOTE: One must be careful with locking in this routine. It's 381 * called from a critical section in machine-dependent code, so 382 * we should refrain from changing any interrupt state. 383 * 384 * We lock the deadproc list, place the proc on that list (using 385 * the p_hash member), and wake up the reaper. 386 */ 387 void 388 exit2(struct proc *p) 389 { 390 mtx_enter(&deadproc_mutex); 391 LIST_INSERT_HEAD(&deadproc, p, p_hash); 392 mtx_leave(&deadproc_mutex); 393 394 wakeup(&deadproc); 395 } 396 397 /* 398 * Process reaper. This is run by a kernel thread to free the resources 399 * of a dead process. Once the resources are free, the process becomes 400 * a zombie, and the parent is allowed to read the undead's status. 401 */ 402 void 403 reaper(void) 404 { 405 struct proc *p; 406 407 KERNEL_UNLOCK(); 408 409 SCHED_ASSERT_UNLOCKED(); 410 411 for (;;) { 412 mtx_enter(&deadproc_mutex); 413 while ((p = LIST_FIRST(&deadproc)) == NULL) 414 msleep(&deadproc, &deadproc_mutex, PVM, "reaper", 0); 415 416 /* Remove us from the deadproc list. */ 417 LIST_REMOVE(p, p_hash); 418 mtx_leave(&deadproc_mutex); 419 420 KERNEL_LOCK(); 421 422 /* 423 * Free the VM resources we're still holding on to. 424 * We must do this from a valid thread because doing 425 * so may block. 426 */ 427 uvm_exit(p); 428 429 /* Process is now a true zombie. */ 430 if ((p->p_flag & P_NOZOMBIE) == 0) { 431 p->p_stat = SZOMB; 432 433 if (P_EXITSIG(p) != 0) 434 prsignal(p->p_p->ps_pptr, P_EXITSIG(p)); 435 /* Wake up the parent so it can get exit status. */ 436 wakeup(p->p_p->ps_pptr); 437 } else { 438 /* Noone will wait for us. Just zap the process now */ 439 proc_zap(p); 440 } 441 442 KERNEL_UNLOCK(); 443 } 444 } 445 446 int 447 sys_wait4(struct proc *q, void *v, register_t *retval) 448 { 449 struct sys_wait4_args /* { 450 syscallarg(pid_t) pid; 451 syscallarg(int *) status; 452 syscallarg(int) options; 453 syscallarg(struct rusage *) rusage; 454 } */ *uap = v; 455 int nfound; 456 struct process *pr; 457 struct proc *p; 458 int status, error; 459 460 if (SCARG(uap, pid) == 0) 461 SCARG(uap, pid) = -q->p_p->ps_pgid; 462 if (SCARG(uap, options) &~ (WUNTRACED|WNOHANG|WALTSIG|WCONTINUED)) 463 return (EINVAL); 464 465 loop: 466 nfound = 0; 467 LIST_FOREACH(pr, &q->p_p->ps_children, ps_sibling) { 468 p = pr->ps_mainproc; 469 if ((p->p_flag & P_NOZOMBIE) || 470 (SCARG(uap, pid) != WAIT_ANY && 471 p->p_pid != SCARG(uap, pid) && 472 pr->ps_pgid != -SCARG(uap, pid))) 473 continue; 474 475 /* 476 * Wait for processes with p_exitsig != SIGCHLD processes only 477 * if WALTSIG is set; wait for processes with pexitsig == 478 * SIGCHLD only if WALTSIG is clear. 479 */ 480 if ((SCARG(uap, options) & WALTSIG) ? 481 (p->p_exitsig == SIGCHLD) : (P_EXITSIG(p) != SIGCHLD)) 482 continue; 483 484 nfound++; 485 if (p->p_stat == SZOMB) { 486 retval[0] = p->p_pid; 487 488 if (SCARG(uap, status)) { 489 status = p->p_xstat; /* convert to int */ 490 error = copyout(&status, 491 SCARG(uap, status), sizeof(status)); 492 if (error) 493 return (error); 494 } 495 if (SCARG(uap, rusage) && 496 (error = copyout(pr->ps_ru, 497 SCARG(uap, rusage), sizeof(struct rusage)))) 498 return (error); 499 proc_finish_wait(q, p); 500 return (0); 501 } 502 if (pr->ps_flags & PS_TRACED && 503 (pr->ps_flags & PS_WAITED) == 0 && pr->ps_single && 504 pr->ps_single->p_stat == SSTOP && 505 (pr->ps_single->p_flag & P_SUSPSINGLE) == 0) { 506 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 507 retval[0] = p->p_pid; 508 509 if (SCARG(uap, status)) { 510 status = W_STOPCODE(pr->ps_single->p_xstat); 511 error = copyout(&status, SCARG(uap, status), 512 sizeof(status)); 513 } else 514 error = 0; 515 return (error); 516 } 517 if (p->p_stat == SSTOP && 518 (pr->ps_flags & PS_WAITED) == 0 && 519 (p->p_flag & P_SUSPSINGLE) == 0 && 520 (pr->ps_flags & PS_TRACED || 521 SCARG(uap, options) & WUNTRACED)) { 522 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 523 retval[0] = p->p_pid; 524 525 if (SCARG(uap, status)) { 526 status = W_STOPCODE(p->p_xstat); 527 error = copyout(&status, SCARG(uap, status), 528 sizeof(status)); 529 } else 530 error = 0; 531 return (error); 532 } 533 if ((SCARG(uap, options) & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 534 atomic_clearbits_int(&p->p_flag, P_CONTINUED); 535 retval[0] = p->p_pid; 536 537 if (SCARG(uap, status)) { 538 status = _WCONTINUED; 539 error = copyout(&status, SCARG(uap, status), 540 sizeof(status)); 541 } else 542 error = 0; 543 return (error); 544 } 545 } 546 if (nfound == 0) 547 return (ECHILD); 548 if (SCARG(uap, options) & WNOHANG) { 549 retval[0] = 0; 550 return (0); 551 } 552 if ((error = tsleep(q->p_p, PWAIT | PCATCH, "wait", 0)) != 0) 553 return (error); 554 goto loop; 555 } 556 557 void 558 proc_finish_wait(struct proc *waiter, struct proc *p) 559 { 560 struct process *pr, *tr; 561 struct rusage *rup; 562 563 /* 564 * If we got the child via a ptrace 'attach', 565 * we need to give it back to the old parent. 566 */ 567 pr = p->p_p; 568 if ((p->p_flag & P_THREAD) == 0 && pr->ps_oppid && 569 (tr = prfind(pr->ps_oppid))) { 570 atomic_clearbits_int(&pr->ps_flags, PS_TRACED); 571 pr->ps_oppid = 0; 572 proc_reparent(pr, tr); 573 if (p->p_exitsig != 0) 574 prsignal(tr, p->p_exitsig); 575 wakeup(tr); 576 } else { 577 scheduler_wait_hook(waiter, p); 578 p->p_xstat = 0; 579 rup = &waiter->p_p->ps_cru; 580 ruadd(rup, pr->ps_ru); 581 proc_zap(p); 582 } 583 } 584 585 /* 586 * make process 'parent' the new parent of process 'child'. 587 */ 588 void 589 proc_reparent(struct process *child, struct process *parent) 590 { 591 592 if (child->ps_pptr == parent) 593 return; 594 595 if (parent == initproc->p_p) 596 child->ps_mainproc->p_exitsig = SIGCHLD; 597 598 LIST_REMOVE(child, ps_sibling); 599 LIST_INSERT_HEAD(&parent->ps_children, child, ps_sibling); 600 child->ps_pptr = parent; 601 } 602 603 void 604 proc_zap(struct proc *p) 605 { 606 struct process *pr = p->p_p; 607 608 /* 609 * Finally finished with old proc entry. 610 * Unlink it from its process group and free it. 611 */ 612 if ((p->p_flag & P_THREAD) == 0) 613 leavepgrp(pr); 614 LIST_REMOVE(p, p_list); /* off zombproc */ 615 if ((p->p_flag & P_THREAD) == 0) { 616 LIST_REMOVE(pr, ps_sibling); 617 618 /* 619 * Decrement the count of procs running with this uid. 620 */ 621 (void)chgproccnt(p->p_cred->p_ruid, -1); 622 } 623 624 /* 625 * Release reference to text vnode 626 */ 627 if (p->p_textvp) 628 vrele(p->p_textvp); 629 630 /* 631 * Remove us from our process list, possibly killing the process 632 * in the process (pun intended). 633 */ 634 if (--pr->ps_refcnt == 0) { 635 if (pr->ps_ptstat != NULL) 636 free(pr->ps_ptstat, M_SUBPROC); 637 pool_put(&rusage_pool, pr->ps_ru); 638 KASSERT(TAILQ_EMPTY(&pr->ps_threads)); 639 limfree(pr->ps_limit); 640 crfree(pr->ps_cred->pc_ucred); 641 pool_put(&pcred_pool, pr->ps_cred); 642 pool_put(&process_pool, pr); 643 nprocesses--; 644 } 645 646 pool_put(&proc_pool, p); 647 nthreads--; 648 } 649