1 /* $OpenBSD: kern_exit.c,v 1.111 2012/04/10 15:50:52 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); 300 301 /* notify interested parties of our demise and clean up */ 302 knote_processexit(pr); 303 304 /* 305 * Notify parent that we're gone. If we have P_NOZOMBIE 306 * or parent has the SAS_NOCLDWAIT flag set, notify process 1 307 * instead (and hope it will handle this situation). 308 */ 309 if ((p->p_flag & P_NOZOMBIE) || 310 (pr->ps_pptr->ps_mainproc->p_sigacts->ps_flags & 311 SAS_NOCLDWAIT)) { 312 struct process *ppr = pr->ps_pptr; 313 proc_reparent(pr, initproc->p_p); 314 /* 315 * If this was the last child of our parent, notify 316 * parent, so in case he was wait(2)ing, he will 317 * continue. 318 */ 319 if (LIST_EMPTY(&ppr->ps_children)) 320 wakeup(ppr); 321 } 322 } 323 324 /* 325 * Release the process's signal state. 326 */ 327 sigactsfree(p); 328 329 /* 330 * Other substructures are freed from reaper and wait(). 331 */ 332 333 /* 334 * If emulation has process exit hook, call it now. 335 */ 336 if (p->p_emul->e_proc_exit) 337 (*p->p_emul->e_proc_exit)(p); 338 339 /* 340 * Finally, call machine-dependent code to switch to a new 341 * context (possibly the idle context). Once we are no longer 342 * using the dead process's vmspace and stack, exit2() will be 343 * called to schedule those resources to be released by the 344 * reaper thread. 345 * 346 * Note that cpu_exit() will end with a call equivalent to 347 * cpu_switch(), finishing our execution (pun intended). 348 */ 349 uvmexp.swtch++; 350 cpu_exit(p); 351 panic("cpu_exit returned"); 352 } 353 354 /* 355 * Locking of this proclist is special; it's accessed in a 356 * critical section of process exit, and thus locking it can't 357 * modify interrupt state. We use a simple spin lock for this 358 * proclist. Processes on this proclist are also on zombproc; 359 * we use the p_hash member to linkup to deadproc. 360 */ 361 struct mutex deadproc_mutex = MUTEX_INITIALIZER(IPL_NONE); 362 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 363 364 /* 365 * We are called from cpu_exit() once it is safe to schedule the 366 * dead process's resources to be freed. 367 * 368 * NOTE: One must be careful with locking in this routine. It's 369 * called from a critical section in machine-dependent code, so 370 * we should refrain from changing any interrupt state. 371 * 372 * We lock the deadproc list, place the proc on that list (using 373 * the p_hash member), and wake up the reaper. 374 */ 375 void 376 exit2(struct proc *p) 377 { 378 mtx_enter(&deadproc_mutex); 379 LIST_INSERT_HEAD(&deadproc, p, p_hash); 380 mtx_leave(&deadproc_mutex); 381 382 wakeup(&deadproc); 383 } 384 385 /* 386 * Process reaper. This is run by a kernel thread to free the resources 387 * of a dead process. Once the resources are free, the process becomes 388 * a zombie, and the parent is allowed to read the undead's status. 389 */ 390 void 391 reaper(void) 392 { 393 struct proc *p; 394 395 KERNEL_UNLOCK(); 396 397 SCHED_ASSERT_UNLOCKED(); 398 399 for (;;) { 400 mtx_enter(&deadproc_mutex); 401 while ((p = LIST_FIRST(&deadproc)) == NULL) 402 msleep(&deadproc, &deadproc_mutex, PVM, "reaper", 0); 403 404 /* Remove us from the deadproc list. */ 405 LIST_REMOVE(p, p_hash); 406 mtx_leave(&deadproc_mutex); 407 408 KERNEL_LOCK(); 409 410 /* 411 * Free the VM resources we're still holding on to. 412 * We must do this from a valid thread because doing 413 * so may block. 414 */ 415 uvm_exit(p); 416 417 /* Process is now a true zombie. */ 418 if ((p->p_flag & P_NOZOMBIE) == 0) { 419 p->p_stat = SZOMB; 420 421 if (P_EXITSIG(p) != 0) 422 prsignal(p->p_p->ps_pptr, P_EXITSIG(p)); 423 /* Wake up the parent so it can get exit status. */ 424 wakeup(p->p_p->ps_pptr); 425 } else { 426 /* Noone will wait for us. Just zap the process now */ 427 proc_zap(p); 428 } 429 430 KERNEL_UNLOCK(); 431 } 432 } 433 434 int 435 sys_wait4(struct proc *q, void *v, register_t *retval) 436 { 437 struct sys_wait4_args /* { 438 syscallarg(pid_t) pid; 439 syscallarg(int *) status; 440 syscallarg(int) options; 441 syscallarg(struct rusage *) rusage; 442 } */ *uap = v; 443 int nfound; 444 struct process *pr; 445 struct proc *p; 446 int status, error; 447 448 if (SCARG(uap, pid) == 0) 449 SCARG(uap, pid) = -q->p_p->ps_pgid; 450 if (SCARG(uap, options) &~ (WUNTRACED|WNOHANG|WALTSIG|WCONTINUED)) 451 return (EINVAL); 452 453 loop: 454 nfound = 0; 455 LIST_FOREACH(pr, &q->p_p->ps_children, ps_sibling) { 456 p = pr->ps_mainproc; 457 if ((p->p_flag & P_NOZOMBIE) || 458 (SCARG(uap, pid) != WAIT_ANY && 459 p->p_pid != SCARG(uap, pid) && 460 pr->ps_pgid != -SCARG(uap, pid))) 461 continue; 462 463 /* 464 * Wait for processes with p_exitsig != SIGCHLD processes only 465 * if WALTSIG is set; wait for processes with pexitsig == 466 * SIGCHLD only if WALTSIG is clear. 467 */ 468 if ((SCARG(uap, options) & WALTSIG) ? 469 (p->p_exitsig == SIGCHLD) : (P_EXITSIG(p) != SIGCHLD)) 470 continue; 471 472 nfound++; 473 if (p->p_stat == SZOMB) { 474 retval[0] = p->p_pid; 475 476 if (SCARG(uap, status)) { 477 status = p->p_xstat; /* convert to int */ 478 error = copyout(&status, 479 SCARG(uap, status), sizeof(status)); 480 if (error) 481 return (error); 482 } 483 if (SCARG(uap, rusage) && 484 (error = copyout(pr->ps_ru, 485 SCARG(uap, rusage), sizeof(struct rusage)))) 486 return (error); 487 proc_finish_wait(q, p); 488 return (0); 489 } 490 if (p->p_stat == SSTOP && 491 (p->p_flag & (P_WAITED|P_SUSPSINGLE)) == 0 && 492 (pr->ps_flags & PS_TRACED || 493 SCARG(uap, options) & WUNTRACED)) { 494 atomic_setbits_int(&p->p_flag, P_WAITED); 495 retval[0] = p->p_pid; 496 497 if (SCARG(uap, status)) { 498 status = W_STOPCODE(p->p_xstat); 499 error = copyout(&status, SCARG(uap, status), 500 sizeof(status)); 501 } else 502 error = 0; 503 return (error); 504 } 505 if ((SCARG(uap, options) & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 506 atomic_clearbits_int(&p->p_flag, P_CONTINUED); 507 retval[0] = p->p_pid; 508 509 if (SCARG(uap, status)) { 510 status = _WCONTINUED; 511 error = copyout(&status, SCARG(uap, status), 512 sizeof(status)); 513 } else 514 error = 0; 515 return (error); 516 } 517 } 518 if (nfound == 0) 519 return (ECHILD); 520 if (SCARG(uap, options) & WNOHANG) { 521 retval[0] = 0; 522 return (0); 523 } 524 if ((error = tsleep(q->p_p, PWAIT | PCATCH, "wait", 0)) != 0) 525 return (error); 526 goto loop; 527 } 528 529 void 530 proc_finish_wait(struct proc *waiter, struct proc *p) 531 { 532 struct process *pr, *tr; 533 struct rusage *rup; 534 535 /* 536 * If we got the child via a ptrace 'attach', 537 * we need to give it back to the old parent. 538 */ 539 pr = p->p_p; 540 if ((p->p_flag & P_THREAD) == 0 && pr->ps_oppid && 541 (tr = prfind(pr->ps_oppid))) { 542 atomic_clearbits_int(&pr->ps_flags, PS_TRACED); 543 pr->ps_oppid = 0; 544 proc_reparent(pr, tr); 545 if (p->p_exitsig != 0) 546 prsignal(tr, p->p_exitsig); 547 wakeup(tr); 548 } else { 549 scheduler_wait_hook(waiter, p); 550 p->p_xstat = 0; 551 rup = &waiter->p_p->ps_cru; 552 ruadd(rup, pr->ps_ru); 553 proc_zap(p); 554 } 555 } 556 557 /* 558 * make process 'parent' the new parent of process 'child'. 559 */ 560 void 561 proc_reparent(struct process *child, struct process *parent) 562 { 563 564 if (child->ps_pptr == parent) 565 return; 566 567 if (parent == initproc->p_p) 568 child->ps_mainproc->p_exitsig = SIGCHLD; 569 570 LIST_REMOVE(child, ps_sibling); 571 LIST_INSERT_HEAD(&parent->ps_children, child, ps_sibling); 572 child->ps_pptr = parent; 573 } 574 575 void 576 proc_zap(struct proc *p) 577 { 578 struct process *pr = p->p_p; 579 580 /* 581 * Finally finished with old proc entry. 582 * Unlink it from its process group and free it. 583 */ 584 if ((p->p_flag & P_THREAD) == 0) 585 leavepgrp(pr); 586 LIST_REMOVE(p, p_list); /* off zombproc */ 587 if ((p->p_flag & P_THREAD) == 0) { 588 LIST_REMOVE(pr, ps_sibling); 589 590 /* 591 * Decrement the count of procs running with this uid. 592 */ 593 (void)chgproccnt(p->p_cred->p_ruid, -1); 594 } 595 596 /* 597 * Release reference to text vnode 598 */ 599 if (p->p_textvp) 600 vrele(p->p_textvp); 601 602 /* 603 * Remove us from our process list, possibly killing the process 604 * in the process (pun intended). 605 */ 606 if (--pr->ps_refcnt == 0) { 607 if (pr->ps_ptstat != NULL) 608 free(pr->ps_ptstat, M_SUBPROC); 609 pool_put(&rusage_pool, pr->ps_ru); 610 KASSERT(TAILQ_EMPTY(&pr->ps_threads)); 611 limfree(pr->ps_limit); 612 crfree(pr->ps_cred->pc_ucred); 613 pool_put(&pcred_pool, pr->ps_cred); 614 pool_put(&process_pool, pr); 615 nprocesses--; 616 } 617 618 pool_put(&proc_pool, p); 619 nthreads--; 620 } 621