1 /* $OpenBSD: kern_exit.c,v 1.122 2013/04/06 03:44:34 tedu 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 74 #include <uvm/uvm_extern.h> 75 76 /* 77 * exit -- 78 * Death of process. 79 */ 80 int 81 sys_exit(struct proc *p, void *v, register_t *retval) 82 { 83 struct sys_exit_args /* { 84 syscallarg(int) rval; 85 } */ *uap = v; 86 87 exit1(p, W_EXITCODE(SCARG(uap, rval), 0), EXIT_NORMAL); 88 /* NOTREACHED */ 89 return (0); 90 } 91 92 int 93 sys___threxit(struct proc *p, void *v, register_t *retval) 94 { 95 struct sys___threxit_args /* { 96 syscallarg(pid_t *) notdead; 97 } */ *uap = v; 98 99 if (SCARG(uap, notdead) != NULL) { 100 pid_t zero = 0; 101 if (copyout(&zero, SCARG(uap, notdead), sizeof(zero))) { 102 psignal(p, SIGSEGV); 103 } 104 } 105 exit1(p, 0, EXIT_THREAD); 106 107 return (0); 108 } 109 110 /* 111 * Exit: deallocate address space and other resources, change proc state 112 * to zombie, and unlink proc from allproc and parent's lists. Save exit 113 * status and rusage for wait(). Check for child processes and orphan them. 114 */ 115 void 116 exit1(struct proc *p, int rv, int flags) 117 { 118 struct process *pr, *qr, *nqr; 119 struct rusage *rup; 120 struct vnode *ovp; 121 122 if (p->p_pid == 1) 123 panic("init died (signal %d, exit %d)", 124 WTERMSIG(rv), WEXITSTATUS(rv)); 125 126 atomic_setbits_int(&p->p_flag, P_WEXIT); 127 128 pr = p->p_p; 129 130 /* single-threaded? */ 131 if (TAILQ_FIRST(&pr->ps_threads) == p && 132 TAILQ_NEXT(p, p_thr_link) == NULL) 133 flags = EXIT_NORMAL; 134 else { 135 /* nope, multi-threaded */ 136 if (flags == EXIT_NORMAL) 137 single_thread_set(p, SINGLE_EXIT, 0); 138 else if (flags == EXIT_THREAD) 139 single_thread_check(p, 0); 140 } 141 142 if (flags == EXIT_NORMAL) { 143 atomic_setbits_int(&pr->ps_flags, PS_EXITING); 144 pr->ps_mainproc->p_xstat = rv; 145 146 /* 147 * If parent is waiting for us to exit or exec, PS_PPWAIT 148 * is set; we wake up the parent early to avoid deadlock. 149 */ 150 if (pr->ps_flags & PS_PPWAIT) { 151 atomic_clearbits_int(&pr->ps_flags, PS_PPWAIT); 152 atomic_clearbits_int(&pr->ps_pptr->ps_flags, 153 PS_ISPWAIT); 154 wakeup(pr->ps_pptr); 155 } 156 } 157 158 /* unlink ourselves from the active threads */ 159 TAILQ_REMOVE(&pr->ps_threads, p, p_thr_link); 160 if ((p->p_flag & P_THREAD) == 0) { 161 /* main thread gotta wait because it has the pid, et al */ 162 while (! TAILQ_EMPTY(&pr->ps_threads)) 163 tsleep(&pr->ps_threads, PUSER, "thrdeath", 0); 164 if (pr->ps_flags & PS_PROFIL) 165 stopprofclock(pr); 166 } else if (TAILQ_EMPTY(&pr->ps_threads)) 167 wakeup(&pr->ps_threads); 168 169 rup = pr->ps_ru; 170 if (rup == NULL) { 171 rup = pool_get(&rusage_pool, PR_WAITOK | PR_ZERO); 172 173 if (pr->ps_ru == NULL) 174 pr->ps_ru = rup; 175 else { 176 pool_put(&rusage_pool, rup); 177 rup = pr->ps_ru; 178 } 179 } 180 p->p_siglist = 0; 181 182 /* 183 * Close open files and release open-file table. 184 */ 185 fdfree(p); 186 187 if ((p->p_flag & P_THREAD) == 0) { 188 timeout_del(&pr->ps_realit_to); 189 timeout_del(&pr->ps_virt_to); 190 timeout_del(&pr->ps_prof_to); 191 #ifdef SYSVSEM 192 semexit(pr); 193 #endif 194 if (SESS_LEADER(pr)) { 195 struct session *sp = pr->ps_session; 196 197 if (sp->s_ttyvp) { 198 /* 199 * Controlling process. 200 * Signal foreground pgrp, 201 * drain controlling terminal 202 * and revoke access to controlling terminal. 203 */ 204 if (sp->s_ttyp->t_session == sp) { 205 if (sp->s_ttyp->t_pgrp) 206 pgsignal(sp->s_ttyp->t_pgrp, 207 SIGHUP, 1); 208 (void) ttywait(sp->s_ttyp); 209 /* 210 * The tty could have been revoked 211 * if we blocked. 212 */ 213 if (sp->s_ttyvp) 214 VOP_REVOKE(sp->s_ttyvp, 215 REVOKEALL); 216 } 217 ovp = sp->s_ttyvp; 218 sp->s_ttyvp = NULL; 219 if (ovp) 220 vrele(ovp); 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 /* 249 * If emulation has process exit hook, call it now. 250 */ 251 if (p->p_emul->e_proc_exit) 252 (*p->p_emul->e_proc_exit)(p); 253 254 /* 255 * Remove proc from pidhash chain so looking it up won't 256 * work. Move it from allproc to zombproc, but do not yet 257 * wake up the reaper. We will put the proc on the 258 * deadproc list later (using the p_hash member), and 259 * wake up the reaper when we do. 260 */ 261 /* 262 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 263 */ 264 p->p_stat = SDEAD; 265 266 LIST_REMOVE(p, p_hash); 267 LIST_REMOVE(p, p_list); 268 LIST_INSERT_HEAD(&zombproc, p, p_list); 269 270 /* 271 * Give orphaned children to init(8). 272 */ 273 if ((p->p_flag & P_THREAD) == 0) { 274 qr = LIST_FIRST(&pr->ps_children); 275 if (qr) /* only need this if any child is S_ZOMB */ 276 wakeup(initproc->p_p); 277 for (; qr != 0; qr = nqr) { 278 nqr = LIST_NEXT(qr, ps_sibling); 279 proc_reparent(qr, initproc->p_p); 280 /* 281 * Traced processes are killed since their 282 * existence means someone is screwing up. 283 */ 284 if (qr->ps_flags & PS_TRACED && 285 !(qr->ps_flags & PS_EXITING)) { 286 atomic_clearbits_int(&qr->ps_flags, PS_TRACED); 287 /* 288 * If single threading is active, 289 * direct the signal to the active 290 * thread to avoid deadlock. 291 */ 292 if (qr->ps_single) 293 ptsignal(qr->ps_single, SIGKILL, 294 STHREAD); 295 else 296 prsignal(qr, SIGKILL); 297 } 298 } 299 } 300 301 302 /* add thread's accumulated rusage into the process's total */ 303 ruadd(rup, &p->p_ru); 304 305 /* 306 * clear %cpu usage during swap 307 */ 308 p->p_pctcpu = 0; 309 310 if ((p->p_flag & P_THREAD) == 0) { 311 /* 312 * Final thread has died, so add on our children's rusage 313 * and calculate the total times 314 */ 315 calcru(&pr->ps_tu, &rup->ru_utime, &rup->ru_stime, NULL); 316 ruadd(rup, &pr->ps_cru); 317 318 /* notify interested parties of our demise and clean up */ 319 knote_processexit(pr); 320 321 /* 322 * Notify parent that we're gone. If we have P_NOZOMBIE 323 * or parent has the SAS_NOCLDWAIT flag set, notify process 1 324 * instead (and hope it will handle this situation). 325 */ 326 if ((p->p_flag & P_NOZOMBIE) || 327 (pr->ps_pptr->ps_mainproc->p_sigacts->ps_flags & 328 SAS_NOCLDWAIT)) { 329 struct process *ppr = pr->ps_pptr; 330 proc_reparent(pr, initproc->p_p); 331 /* 332 * If this was the last child of our parent, notify 333 * parent, so in case he was wait(2)ing, he will 334 * continue. 335 */ 336 if (LIST_EMPTY(&ppr->ps_children)) 337 wakeup(ppr); 338 } 339 } 340 341 /* 342 * Release the process's signal state. 343 */ 344 sigactsfree(p); 345 346 /* 347 * Other substructures are freed from reaper and wait(). 348 */ 349 350 /* 351 * Finally, call machine-dependent code to switch to a new 352 * context (possibly the idle context). Once we are no longer 353 * using the dead process's vmspace and stack, exit2() will be 354 * called to schedule those resources to be released by the 355 * reaper thread. 356 * 357 * Note that cpu_exit() will end with a call equivalent to 358 * cpu_switch(), finishing our execution (pun intended). 359 */ 360 uvmexp.swtch++; 361 cpu_exit(p); 362 panic("cpu_exit returned"); 363 } 364 365 /* 366 * Locking of this proclist is special; it's accessed in a 367 * critical section of process exit, and thus locking it can't 368 * modify interrupt state. We use a simple spin lock for this 369 * proclist. Processes on this proclist are also on zombproc; 370 * we use the p_hash member to linkup to deadproc. 371 */ 372 struct mutex deadproc_mutex = MUTEX_INITIALIZER(IPL_NONE); 373 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 374 375 /* 376 * We are called from cpu_exit() once it is safe to schedule the 377 * dead process's resources to be freed. 378 * 379 * NOTE: One must be careful with locking in this routine. It's 380 * called from a critical section in machine-dependent code, so 381 * we should refrain from changing any interrupt state. 382 * 383 * We lock the deadproc list, place the proc on that list (using 384 * the p_hash member), and wake up the reaper. 385 */ 386 void 387 exit2(struct proc *p) 388 { 389 mtx_enter(&deadproc_mutex); 390 LIST_INSERT_HEAD(&deadproc, p, p_hash); 391 mtx_leave(&deadproc_mutex); 392 393 wakeup(&deadproc); 394 } 395 396 /* 397 * Process reaper. This is run by a kernel thread to free the resources 398 * of a dead process. Once the resources are free, the process becomes 399 * a zombie, and the parent is allowed to read the undead's status. 400 */ 401 void 402 reaper(void) 403 { 404 struct proc *p; 405 406 KERNEL_UNLOCK(); 407 408 SCHED_ASSERT_UNLOCKED(); 409 410 for (;;) { 411 mtx_enter(&deadproc_mutex); 412 while ((p = LIST_FIRST(&deadproc)) == NULL) 413 msleep(&deadproc, &deadproc_mutex, PVM, "reaper", 0); 414 415 /* Remove us from the deadproc list. */ 416 LIST_REMOVE(p, p_hash); 417 mtx_leave(&deadproc_mutex); 418 419 KERNEL_LOCK(); 420 421 /* 422 * Free the VM resources we're still holding on to. 423 * We must do this from a valid thread because doing 424 * so may block. 425 */ 426 uvm_exit(p); 427 428 /* Process is now a true zombie. */ 429 if ((p->p_flag & P_NOZOMBIE) == 0) { 430 p->p_stat = SZOMB; 431 432 if (P_EXITSIG(p) != 0) 433 prsignal(p->p_p->ps_pptr, P_EXITSIG(p)); 434 /* Wake up the parent so it can get exit status. */ 435 wakeup(p->p_p->ps_pptr); 436 } else { 437 /* Noone will wait for us. Just zap the process now */ 438 proc_zap(p); 439 } 440 441 KERNEL_UNLOCK(); 442 } 443 } 444 445 int 446 sys_wait4(struct proc *q, void *v, register_t *retval) 447 { 448 struct sys_wait4_args /* { 449 syscallarg(pid_t) pid; 450 syscallarg(int *) status; 451 syscallarg(int) options; 452 syscallarg(struct rusage *) rusage; 453 } */ *uap = v; 454 int nfound; 455 struct process *pr; 456 struct proc *p; 457 int status, error; 458 459 if (SCARG(uap, pid) == 0) 460 SCARG(uap, pid) = -q->p_p->ps_pgid; 461 if (SCARG(uap, options) &~ (WUNTRACED|WNOHANG|WALTSIG|WCONTINUED)) 462 return (EINVAL); 463 464 loop: 465 nfound = 0; 466 LIST_FOREACH(pr, &q->p_p->ps_children, ps_sibling) { 467 p = pr->ps_mainproc; 468 if ((p->p_flag & P_NOZOMBIE) || 469 (SCARG(uap, pid) != WAIT_ANY && 470 p->p_pid != SCARG(uap, pid) && 471 pr->ps_pgid != -SCARG(uap, pid))) 472 continue; 473 474 /* 475 * Wait for processes with p_exitsig != SIGCHLD processes only 476 * if WALTSIG is set; wait for processes with pexitsig == 477 * SIGCHLD only if WALTSIG is clear. 478 */ 479 if ((SCARG(uap, options) & WALTSIG) ? 480 (p->p_exitsig == SIGCHLD) : (P_EXITSIG(p) != SIGCHLD)) 481 continue; 482 483 nfound++; 484 if (p->p_stat == SZOMB) { 485 retval[0] = p->p_pid; 486 487 if (SCARG(uap, status)) { 488 status = p->p_xstat; /* convert to int */ 489 error = copyout(&status, 490 SCARG(uap, status), sizeof(status)); 491 if (error) 492 return (error); 493 } 494 if (SCARG(uap, rusage) && 495 (error = copyout(pr->ps_ru, 496 SCARG(uap, rusage), sizeof(struct rusage)))) 497 return (error); 498 proc_finish_wait(q, p); 499 return (0); 500 } 501 if (pr->ps_flags & PS_TRACED && 502 (pr->ps_flags & PS_WAITED) == 0 && pr->ps_single && 503 pr->ps_single->p_stat == SSTOP && 504 (pr->ps_single->p_flag & P_SUSPSINGLE) == 0) { 505 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 506 retval[0] = p->p_pid; 507 508 if (SCARG(uap, status)) { 509 status = W_STOPCODE(pr->ps_single->p_xstat); 510 error = copyout(&status, SCARG(uap, status), 511 sizeof(status)); 512 } else 513 error = 0; 514 return (error); 515 } 516 if (p->p_stat == SSTOP && 517 (pr->ps_flags & PS_WAITED) == 0 && 518 (p->p_flag & P_SUSPSINGLE) == 0 && 519 (pr->ps_flags & PS_TRACED || 520 SCARG(uap, options) & WUNTRACED)) { 521 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 522 retval[0] = p->p_pid; 523 524 if (SCARG(uap, status)) { 525 status = W_STOPCODE(p->p_xstat); 526 error = copyout(&status, SCARG(uap, status), 527 sizeof(status)); 528 } else 529 error = 0; 530 return (error); 531 } 532 if ((SCARG(uap, options) & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 533 atomic_clearbits_int(&p->p_flag, P_CONTINUED); 534 retval[0] = p->p_pid; 535 536 if (SCARG(uap, status)) { 537 status = _WCONTINUED; 538 error = copyout(&status, SCARG(uap, status), 539 sizeof(status)); 540 } else 541 error = 0; 542 return (error); 543 } 544 } 545 if (nfound == 0) 546 return (ECHILD); 547 if (SCARG(uap, options) & WNOHANG) { 548 retval[0] = 0; 549 return (0); 550 } 551 if ((error = tsleep(q->p_p, PWAIT | PCATCH, "wait", 0)) != 0) 552 return (error); 553 goto loop; 554 } 555 556 void 557 proc_finish_wait(struct proc *waiter, struct proc *p) 558 { 559 struct process *pr, *tr; 560 struct rusage *rup; 561 562 /* 563 * If we got the child via a ptrace 'attach', 564 * we need to give it back to the old parent. 565 */ 566 pr = p->p_p; 567 if ((p->p_flag & P_THREAD) == 0 && pr->ps_oppid && 568 (tr = prfind(pr->ps_oppid))) { 569 atomic_clearbits_int(&pr->ps_flags, PS_TRACED); 570 pr->ps_oppid = 0; 571 proc_reparent(pr, tr); 572 if (p->p_exitsig != 0) 573 prsignal(tr, p->p_exitsig); 574 wakeup(tr); 575 } else { 576 scheduler_wait_hook(waiter, p); 577 p->p_xstat = 0; 578 rup = &waiter->p_p->ps_cru; 579 ruadd(rup, pr->ps_ru); 580 proc_zap(p); 581 } 582 } 583 584 /* 585 * make process 'parent' the new parent of process 'child'. 586 */ 587 void 588 proc_reparent(struct process *child, struct process *parent) 589 { 590 591 if (child->ps_pptr == parent) 592 return; 593 594 if (parent == initproc->p_p) 595 child->ps_mainproc->p_exitsig = SIGCHLD; 596 597 LIST_REMOVE(child, ps_sibling); 598 LIST_INSERT_HEAD(&parent->ps_children, child, ps_sibling); 599 child->ps_pptr = parent; 600 } 601 602 void 603 proc_zap(struct proc *p) 604 { 605 struct process *pr = p->p_p; 606 struct vnode *otvp; 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 otvp = p->p_textvp; 628 p->p_textvp = NULL; 629 if (otvp) 630 vrele(otvp); 631 632 /* 633 * Remove us from our process list, possibly killing the process 634 * in the process (pun intended). 635 */ 636 if (--pr->ps_refcnt == 0) { 637 if (pr->ps_ptstat != NULL) 638 free(pr->ps_ptstat, M_SUBPROC); 639 pool_put(&rusage_pool, pr->ps_ru); 640 KASSERT(TAILQ_EMPTY(&pr->ps_threads)); 641 limfree(pr->ps_limit); 642 crfree(pr->ps_cred->pc_ucred); 643 pool_put(&pcred_pool, pr->ps_cred); 644 pool_put(&process_pool, pr); 645 nprocesses--; 646 } 647 648 pool_put(&proc_pool, p); 649 nthreads--; 650 } 651