1 /* $OpenBSD: kern_exit.c,v 1.109 2012/03/23 15:51:26 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 } 142 143 if (flags == EXIT_NORMAL) { 144 atomic_setbits_int(&pr->ps_flags, PS_EXITING); 145 pr->ps_mainproc->p_xstat = rv; 146 147 /* 148 * If parent is waiting for us to exit or exec, PS_PPWAIT 149 * is set; we wake up the parent early to avoid deadlock. 150 */ 151 if (pr->ps_flags & PS_PPWAIT) { 152 atomic_clearbits_int(&pr->ps_flags, PS_PPWAIT); 153 atomic_clearbits_int(&pr->ps_pptr->ps_flags, 154 PS_ISPWAIT); 155 wakeup(pr->ps_pptr); 156 } 157 } 158 159 /* unlink ourselves from the active threads */ 160 TAILQ_REMOVE(&pr->ps_threads, p, p_thr_link); 161 if ((p->p_flag & P_THREAD) == 0) { 162 /* main thread gotta wait because it has the pid, et al */ 163 while (! TAILQ_EMPTY(&pr->ps_threads)) 164 tsleep(&pr->ps_threads, PUSER, "thrdeath", 0); 165 } else if (TAILQ_EMPTY(&pr->ps_threads)) 166 wakeup(&pr->ps_threads); 167 168 if (p->p_flag & P_PROFIL) 169 stopprofclock(p); 170 rup = pr->ps_ru; 171 if (rup == NULL) { 172 rup = pool_get(&rusage_pool, PR_WAITOK | PR_ZERO); 173 174 if (pr->ps_ru == NULL) 175 pr->ps_ru = rup; 176 else { 177 pool_put(&rusage_pool, rup); 178 rup = pr->ps_ru; 179 } 180 } 181 p->p_siglist = 0; 182 183 /* 184 * Close open files and release open-file table. 185 */ 186 fdfree(p); 187 188 if ((p->p_flag & P_THREAD) == 0) { 189 timeout_del(&pr->ps_realit_to); 190 timeout_del(&pr->ps_virt_to); 191 timeout_del(&pr->ps_prof_to); 192 #ifdef SYSVSEM 193 semexit(pr); 194 #endif 195 if (SESS_LEADER(pr)) { 196 struct session *sp = pr->ps_session; 197 198 if (sp->s_ttyvp) { 199 /* 200 * Controlling process. 201 * Signal foreground pgrp, 202 * drain controlling terminal 203 * and revoke access to controlling terminal. 204 */ 205 if (sp->s_ttyp->t_session == sp) { 206 if (sp->s_ttyp->t_pgrp) 207 pgsignal(sp->s_ttyp->t_pgrp, 208 SIGHUP, 1); 209 (void) ttywait(sp->s_ttyp); 210 /* 211 * The tty could have been revoked 212 * if we blocked. 213 */ 214 if (sp->s_ttyvp) 215 VOP_REVOKE(sp->s_ttyvp, 216 REVOKEALL); 217 } 218 if (sp->s_ttyvp) 219 vrele(sp->s_ttyvp); 220 sp->s_ttyvp = NULL; 221 /* 222 * s_ttyp is not zero'd; we use this to 223 * indicate that the session once had a 224 * controlling terminal. (for logging and 225 * informational purposes) 226 */ 227 } 228 sp->s_leader = NULL; 229 } 230 fixjobc(pr, pr->ps_pgrp, 0); 231 232 #ifdef ACCOUNTING 233 (void)acct_process(p); 234 #endif 235 236 #ifdef KTRACE 237 /* release trace file */ 238 if (pr->ps_tracevp) 239 ktrcleartrace(pr); 240 #endif 241 } 242 243 #if NSYSTRACE > 0 244 if (ISSET(p->p_flag, P_SYSTRACE)) 245 systrace_exit(p); 246 #endif 247 /* 248 * Remove proc from pidhash chain so looking it up won't 249 * work. Move it from allproc to zombproc, but do not yet 250 * wake up the reaper. We will put the proc on the 251 * deadproc list later (using the p_hash member), and 252 * wake up the reaper when we do. 253 */ 254 /* 255 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 256 */ 257 p->p_stat = SDEAD; 258 259 LIST_REMOVE(p, p_hash); 260 LIST_REMOVE(p, p_list); 261 LIST_INSERT_HEAD(&zombproc, p, p_list); 262 263 /* 264 * Give orphaned children to init(8). 265 */ 266 if ((p->p_flag & P_THREAD) == 0) { 267 qr = LIST_FIRST(&pr->ps_children); 268 if (qr) /* only need this if any child is S_ZOMB */ 269 wakeup(initproc->p_p); 270 for (; qr != 0; qr = nqr) { 271 nqr = LIST_NEXT(qr, ps_sibling); 272 proc_reparent(qr, initproc->p_p); 273 /* 274 * Traced processes are killed 275 * since their existence means someone is screwing up. 276 */ 277 if (qr->ps_flags & PS_TRACED) { 278 atomic_clearbits_int(&qr->ps_flags, PS_TRACED); 279 prsignal(qr, SIGKILL); 280 } 281 } 282 } 283 284 285 /* add thread's accumulated rusage into the process's total */ 286 ruadd(rup, &p->p_ru); 287 288 /* 289 * clear %cpu usage during swap 290 */ 291 p->p_pctcpu = 0; 292 293 if ((p->p_flag & P_THREAD) == 0) { 294 /* 295 * Final thread has died, so add on our children's rusage 296 * and calculate the total times 297 */ 298 calcru(&pr->ps_tu, &rup->ru_utime, &rup->ru_stime, NULL); 299 ruadd(rup, &pr->ps_cru); 300 timeradd(&rup->ru_utime, &pr->ps_cru.ru_utime, &rup->ru_utime); 301 timeradd(&rup->ru_stime, &pr->ps_cru.ru_stime, &rup->ru_stime); 302 303 /* notify interested parties of our demise and clean up */ 304 knote_processexit(pr); 305 306 /* 307 * Notify parent that we're gone. If we have P_NOZOMBIE 308 * or parent has the SAS_NOCLDWAIT flag set, notify process 1 309 * instead (and hope it will handle this situation). 310 */ 311 if ((p->p_flag & P_NOZOMBIE) || 312 (pr->ps_pptr->ps_mainproc->p_sigacts->ps_flags & 313 SAS_NOCLDWAIT)) { 314 struct process *ppr = pr->ps_pptr; 315 proc_reparent(pr, initproc->p_p); 316 /* 317 * If this was the last child of our parent, notify 318 * parent, so in case he was wait(2)ing, he will 319 * continue. 320 */ 321 if (LIST_EMPTY(&ppr->ps_children)) 322 wakeup(ppr); 323 } 324 } 325 326 /* 327 * Release the process's signal state. 328 */ 329 sigactsfree(p); 330 331 /* 332 * Other substructures are freed from reaper and wait(). 333 */ 334 335 /* 336 * If emulation has process exit hook, call it now. 337 */ 338 if (p->p_emul->e_proc_exit) 339 (*p->p_emul->e_proc_exit)(p); 340 341 /* 342 * Finally, call machine-dependent code to switch to a new 343 * context (possibly the idle context). Once we are no longer 344 * using the dead process's vmspace and stack, exit2() will be 345 * called to schedule those resources to be released by the 346 * reaper thread. 347 * 348 * Note that cpu_exit() will end with a call equivalent to 349 * cpu_switch(), finishing our execution (pun intended). 350 */ 351 uvmexp.swtch++; 352 cpu_exit(p); 353 panic("cpu_exit returned"); 354 } 355 356 /* 357 * Locking of this proclist is special; it's accessed in a 358 * critical section of process exit, and thus locking it can't 359 * modify interrupt state. We use a simple spin lock for this 360 * proclist. Processes on this proclist are also on zombproc; 361 * we use the p_hash member to linkup to deadproc. 362 */ 363 struct mutex deadproc_mutex = MUTEX_INITIALIZER(IPL_NONE); 364 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 365 366 /* 367 * We are called from cpu_exit() once it is safe to schedule the 368 * dead process's resources to be freed. 369 * 370 * NOTE: One must be careful with locking in this routine. It's 371 * called from a critical section in machine-dependent code, so 372 * we should refrain from changing any interrupt state. 373 * 374 * We lock the deadproc list, place the proc on that list (using 375 * the p_hash member), and wake up the reaper. 376 */ 377 void 378 exit2(struct proc *p) 379 { 380 mtx_enter(&deadproc_mutex); 381 LIST_INSERT_HEAD(&deadproc, p, p_hash); 382 mtx_leave(&deadproc_mutex); 383 384 wakeup(&deadproc); 385 } 386 387 /* 388 * Process reaper. This is run by a kernel thread to free the resources 389 * of a dead process. Once the resources are free, the process becomes 390 * a zombie, and the parent is allowed to read the undead's status. 391 */ 392 void 393 reaper(void) 394 { 395 struct proc *p; 396 397 KERNEL_UNLOCK(); 398 399 SCHED_ASSERT_UNLOCKED(); 400 401 for (;;) { 402 mtx_enter(&deadproc_mutex); 403 while ((p = LIST_FIRST(&deadproc)) == NULL) 404 msleep(&deadproc, &deadproc_mutex, PVM, "reaper", 0); 405 406 /* Remove us from the deadproc list. */ 407 LIST_REMOVE(p, p_hash); 408 mtx_leave(&deadproc_mutex); 409 410 KERNEL_LOCK(); 411 412 /* 413 * Free the VM resources we're still holding on to. 414 * We must do this from a valid thread because doing 415 * so may block. 416 */ 417 uvm_exit(p); 418 419 /* Process is now a true zombie. */ 420 if ((p->p_flag & P_NOZOMBIE) == 0) { 421 p->p_stat = SZOMB; 422 423 if (P_EXITSIG(p) != 0) 424 prsignal(p->p_p->ps_pptr, P_EXITSIG(p)); 425 /* Wake up the parent so it can get exit status. */ 426 wakeup(p->p_p->ps_pptr); 427 } else { 428 /* Noone will wait for us. Just zap the process now */ 429 proc_zap(p); 430 } 431 432 KERNEL_UNLOCK(); 433 } 434 } 435 436 int 437 sys_wait4(struct proc *q, void *v, register_t *retval) 438 { 439 struct sys_wait4_args /* { 440 syscallarg(pid_t) pid; 441 syscallarg(int *) status; 442 syscallarg(int) options; 443 syscallarg(struct rusage *) rusage; 444 } */ *uap = v; 445 int nfound; 446 struct process *pr; 447 struct proc *p; 448 int status, error; 449 450 if (SCARG(uap, pid) == 0) 451 SCARG(uap, pid) = -q->p_p->ps_pgid; 452 if (SCARG(uap, options) &~ (WUNTRACED|WNOHANG|WALTSIG|WCONTINUED)) 453 return (EINVAL); 454 455 loop: 456 nfound = 0; 457 LIST_FOREACH(pr, &q->p_p->ps_children, ps_sibling) { 458 p = pr->ps_mainproc; 459 if ((p->p_flag & P_NOZOMBIE) || 460 (SCARG(uap, pid) != WAIT_ANY && 461 p->p_pid != SCARG(uap, pid) && 462 pr->ps_pgid != -SCARG(uap, pid))) 463 continue; 464 465 /* 466 * Wait for processes with p_exitsig != SIGCHLD processes only 467 * if WALTSIG is set; wait for processes with pexitsig == 468 * SIGCHLD only if WALTSIG is clear. 469 */ 470 if ((SCARG(uap, options) & WALTSIG) ? 471 (p->p_exitsig == SIGCHLD) : (P_EXITSIG(p) != SIGCHLD)) 472 continue; 473 474 nfound++; 475 if (p->p_stat == SZOMB) { 476 retval[0] = p->p_pid; 477 478 if (SCARG(uap, status)) { 479 status = p->p_xstat; /* convert to int */ 480 error = copyout(&status, 481 SCARG(uap, status), sizeof(status)); 482 if (error) 483 return (error); 484 } 485 if (SCARG(uap, rusage) && 486 (error = copyout(pr->ps_ru, 487 SCARG(uap, rusage), sizeof(struct rusage)))) 488 return (error); 489 proc_finish_wait(q, p); 490 return (0); 491 } 492 if (p->p_stat == SSTOP && 493 (p->p_flag & (P_WAITED|P_SUSPSINGLE)) == 0 && 494 (pr->ps_flags & PS_TRACED || 495 SCARG(uap, options) & WUNTRACED)) { 496 atomic_setbits_int(&p->p_flag, P_WAITED); 497 retval[0] = p->p_pid; 498 499 if (SCARG(uap, status)) { 500 status = W_STOPCODE(p->p_xstat); 501 error = copyout(&status, SCARG(uap, status), 502 sizeof(status)); 503 } else 504 error = 0; 505 return (error); 506 } 507 if ((SCARG(uap, options) & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 508 atomic_clearbits_int(&p->p_flag, P_CONTINUED); 509 retval[0] = p->p_pid; 510 511 if (SCARG(uap, status)) { 512 status = _WCONTINUED; 513 error = copyout(&status, SCARG(uap, status), 514 sizeof(status)); 515 } else 516 error = 0; 517 return (error); 518 } 519 } 520 if (nfound == 0) 521 return (ECHILD); 522 if (SCARG(uap, options) & WNOHANG) { 523 retval[0] = 0; 524 return (0); 525 } 526 if ((error = tsleep(q->p_p, PWAIT | PCATCH, "wait", 0)) != 0) 527 return (error); 528 goto loop; 529 } 530 531 void 532 proc_finish_wait(struct proc *waiter, struct proc *p) 533 { 534 struct process *pr, *tr; 535 struct rusage *rup; 536 537 /* 538 * If we got the child via a ptrace 'attach', 539 * we need to give it back to the old parent. 540 */ 541 pr = p->p_p; 542 if ((p->p_flag & P_THREAD) == 0 && pr->ps_oppid && 543 (tr = prfind(pr->ps_oppid))) { 544 atomic_clearbits_int(&pr->ps_flags, PS_TRACED); 545 pr->ps_oppid = 0; 546 proc_reparent(pr, tr); 547 if (p->p_exitsig != 0) 548 prsignal(tr, p->p_exitsig); 549 wakeup(tr); 550 } else { 551 scheduler_wait_hook(waiter, p); 552 p->p_xstat = 0; 553 rup = &waiter->p_p->ps_cru; 554 ruadd(rup, pr->ps_ru); 555 timeradd(&rup->ru_utime, &pr->ps_ru->ru_utime, &rup->ru_utime); 556 timeradd(&rup->ru_stime, &pr->ps_ru->ru_stime, &rup->ru_stime); 557 proc_zap(p); 558 } 559 } 560 561 /* 562 * make process 'parent' the new parent of process 'child'. 563 */ 564 void 565 proc_reparent(struct process *child, struct process *parent) 566 { 567 568 if (child->ps_pptr == parent) 569 return; 570 571 if (parent == initproc->p_p) 572 child->ps_mainproc->p_exitsig = SIGCHLD; 573 574 LIST_REMOVE(child, ps_sibling); 575 LIST_INSERT_HEAD(&parent->ps_children, child, ps_sibling); 576 child->ps_pptr = parent; 577 } 578 579 void 580 proc_zap(struct proc *p) 581 { 582 struct process *pr = p->p_p; 583 584 /* 585 * Finally finished with old proc entry. 586 * Unlink it from its process group and free it. 587 */ 588 if ((p->p_flag & P_THREAD) == 0) 589 leavepgrp(pr); 590 LIST_REMOVE(p, p_list); /* off zombproc */ 591 if ((p->p_flag & P_THREAD) == 0) 592 LIST_REMOVE(pr, ps_sibling); 593 594 /* 595 * Decrement the count of procs running with this uid. 596 */ 597 (void)chgproccnt(p->p_cred->p_ruid, -1); 598 599 /* 600 * Release reference to text vnode 601 */ 602 if (p->p_textvp) 603 vrele(p->p_textvp); 604 605 /* 606 * Remove us from our process list, possibly killing the process 607 * in the process (pun intended). 608 */ 609 if (--pr->ps_refcnt == 0) { 610 if (pr->ps_ptstat != NULL) 611 free(pr->ps_ptstat, M_SUBPROC); 612 pool_put(&rusage_pool, pr->ps_ru); 613 KASSERT(TAILQ_EMPTY(&pr->ps_threads)); 614 limfree(pr->ps_limit); 615 crfree(pr->ps_cred->pc_ucred); 616 pool_put(&pcred_pool, pr->ps_cred); 617 pool_put(&process_pool, pr); 618 } 619 620 pool_put(&proc_pool, p); 621 nprocs--; 622 } 623