1 /* $OpenBSD: kern_exit.c,v 1.108 2012/03/10 05:54:28 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; 123 124 if (p->p_pid == 1) 125 panic("init died (signal %d, exit %d)", 126 WTERMSIG(rv), WEXITSTATUS(rv)); 127 128 atomic_setbits_int(&p->p_flag, P_WEXIT); 129 130 pr = p->p_p; 131 132 /* single-threaded? */ 133 if (TAILQ_FIRST(&pr->ps_threads) == p && 134 TAILQ_NEXT(p, p_thr_link) == NULL) 135 flags = EXIT_NORMAL; 136 else { 137 /* nope, multi-threaded */ 138 if (flags == EXIT_NORMAL) 139 single_thread_set(p, SINGLE_EXIT, 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 } else if (TAILQ_EMPTY(&pr->ps_threads)) 165 wakeup(&pr->ps_threads); 166 167 if (p->p_flag & P_PROFIL) 168 stopprofclock(p); 169 p->p_ru = pool_get(&rusage_pool, PR_WAITOK); 170 p->p_siglist = 0; 171 timeout_del(&p->p_realit_to); 172 timeout_del(&p->p_stats->p_virt_to); 173 timeout_del(&p->p_stats->p_prof_to); 174 175 /* 176 * Close open files and release open-file table. 177 */ 178 fdfree(p); 179 180 if ((p->p_flag & P_THREAD) == 0) { 181 #ifdef SYSVSEM 182 semexit(pr); 183 #endif 184 if (SESS_LEADER(pr)) { 185 struct session *sp = pr->ps_session; 186 187 if (sp->s_ttyvp) { 188 /* 189 * Controlling process. 190 * Signal foreground pgrp, 191 * drain controlling terminal 192 * and revoke access to controlling terminal. 193 */ 194 if (sp->s_ttyp->t_session == sp) { 195 if (sp->s_ttyp->t_pgrp) 196 pgsignal(sp->s_ttyp->t_pgrp, 197 SIGHUP, 1); 198 (void) ttywait(sp->s_ttyp); 199 /* 200 * The tty could have been revoked 201 * if we blocked. 202 */ 203 if (sp->s_ttyvp) 204 VOP_REVOKE(sp->s_ttyvp, 205 REVOKEALL); 206 } 207 if (sp->s_ttyvp) 208 vrele(sp->s_ttyvp); 209 sp->s_ttyvp = NULL; 210 /* 211 * s_ttyp is not zero'd; we use this to 212 * indicate that the session once had a 213 * controlling terminal. (for logging and 214 * informational purposes) 215 */ 216 } 217 sp->s_leader = NULL; 218 } 219 fixjobc(pr, pr->ps_pgrp, 0); 220 221 #ifdef ACCOUNTING 222 (void)acct_process(p); 223 #endif 224 225 #ifdef KTRACE 226 /* release trace file */ 227 if (pr->ps_tracevp) 228 ktrcleartrace(pr); 229 #endif 230 } 231 232 #if NSYSTRACE > 0 233 if (ISSET(p->p_flag, P_SYSTRACE)) 234 systrace_exit(p); 235 #endif 236 /* 237 * Remove proc from pidhash chain so looking it up won't 238 * work. Move it from allproc to zombproc, but do not yet 239 * wake up the reaper. We will put the proc on the 240 * deadproc list later (using the p_hash member), and 241 * wake up the reaper when we do. 242 */ 243 /* 244 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 245 */ 246 p->p_stat = SDEAD; 247 248 LIST_REMOVE(p, p_hash); 249 LIST_REMOVE(p, p_list); 250 LIST_INSERT_HEAD(&zombproc, p, p_list); 251 252 /* 253 * Give orphaned children to init(8). 254 */ 255 if ((p->p_flag & P_THREAD) == 0) { 256 qr = LIST_FIRST(&pr->ps_children); 257 if (qr) /* only need this if any child is S_ZOMB */ 258 wakeup(initproc->p_p); 259 for (; qr != 0; qr = nqr) { 260 nqr = LIST_NEXT(qr, ps_sibling); 261 proc_reparent(qr, initproc->p_p); 262 /* 263 * Traced processes are killed 264 * since their existence means someone is screwing up. 265 */ 266 if (qr->ps_flags & PS_TRACED) { 267 atomic_clearbits_int(&qr->ps_flags, PS_TRACED); 268 prsignal(qr, SIGKILL); 269 } 270 } 271 } 272 273 274 /* 275 * Save exit status and final rusage info, adding in child rusage 276 * info and self times. 277 */ 278 *p->p_ru = p->p_stats->p_ru; 279 calcru(p, &p->p_ru->ru_utime, &p->p_ru->ru_stime, NULL); 280 ruadd(p->p_ru, &p->p_stats->p_cru); 281 282 /* 283 * clear %cpu usage during swap 284 */ 285 p->p_pctcpu = 0; 286 287 if ((p->p_flag & P_THREAD) == 0) { 288 /* notify interested parties of our demise and clean up */ 289 knote_processexit(pr); 290 291 /* 292 * Notify parent that we're gone. If we have P_NOZOMBIE 293 * or parent has the SAS_NOCLDWAIT flag set, notify process 1 294 * instead (and hope it will handle this situation). 295 */ 296 if ((p->p_flag & P_NOZOMBIE) || 297 (pr->ps_pptr->ps_mainproc->p_sigacts->ps_flags & 298 SAS_NOCLDWAIT)) { 299 struct process *ppr = pr->ps_pptr; 300 proc_reparent(pr, initproc->p_p); 301 /* 302 * If this was the last child of our parent, notify 303 * parent, so in case he was wait(2)ing, he will 304 * continue. 305 */ 306 if (LIST_EMPTY(&ppr->ps_children)) 307 wakeup(ppr); 308 } 309 } 310 311 /* 312 * Release the process's signal state. 313 */ 314 sigactsfree(p); 315 316 /* 317 * Other substructures are freed from reaper and wait(). 318 */ 319 320 /* 321 * If emulation has process exit hook, call it now. 322 */ 323 if (p->p_emul->e_proc_exit) 324 (*p->p_emul->e_proc_exit)(p); 325 326 /* 327 * Finally, call machine-dependent code to switch to a new 328 * context (possibly the idle context). Once we are no longer 329 * using the dead process's vmspace and stack, exit2() will be 330 * called to schedule those resources to be released by the 331 * reaper thread. 332 * 333 * Note that cpu_exit() will end with a call equivalent to 334 * cpu_switch(), finishing our execution (pun intended). 335 */ 336 uvmexp.swtch++; 337 cpu_exit(p); 338 panic("cpu_exit returned"); 339 } 340 341 /* 342 * Locking of this proclist is special; it's accessed in a 343 * critical section of process exit, and thus locking it can't 344 * modify interrupt state. We use a simple spin lock for this 345 * proclist. Processes on this proclist are also on zombproc; 346 * we use the p_hash member to linkup to deadproc. 347 */ 348 struct mutex deadproc_mutex = MUTEX_INITIALIZER(IPL_NONE); 349 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 350 351 /* 352 * We are called from cpu_exit() once it is safe to schedule the 353 * dead process's resources to be freed. 354 * 355 * NOTE: One must be careful with locking in this routine. It's 356 * called from a critical section in machine-dependent code, so 357 * we should refrain from changing any interrupt state. 358 * 359 * We lock the deadproc list, place the proc on that list (using 360 * the p_hash member), and wake up the reaper. 361 */ 362 void 363 exit2(struct proc *p) 364 { 365 mtx_enter(&deadproc_mutex); 366 LIST_INSERT_HEAD(&deadproc, p, p_hash); 367 mtx_leave(&deadproc_mutex); 368 369 wakeup(&deadproc); 370 } 371 372 /* 373 * Process reaper. This is run by a kernel thread to free the resources 374 * of a dead process. Once the resources are free, the process becomes 375 * a zombie, and the parent is allowed to read the undead's status. 376 */ 377 void 378 reaper(void) 379 { 380 struct proc *p; 381 382 KERNEL_UNLOCK(); 383 384 SCHED_ASSERT_UNLOCKED(); 385 386 for (;;) { 387 mtx_enter(&deadproc_mutex); 388 while ((p = LIST_FIRST(&deadproc)) == NULL) 389 msleep(&deadproc, &deadproc_mutex, PVM, "reaper", 0); 390 391 /* Remove us from the deadproc list. */ 392 LIST_REMOVE(p, p_hash); 393 mtx_leave(&deadproc_mutex); 394 395 KERNEL_LOCK(); 396 397 /* 398 * Free the VM resources we're still holding on to. 399 * We must do this from a valid thread because doing 400 * so may block. 401 */ 402 uvm_exit(p); 403 404 /* Process is now a true zombie. */ 405 if ((p->p_flag & P_NOZOMBIE) == 0) { 406 p->p_stat = SZOMB; 407 408 if (P_EXITSIG(p) != 0) 409 prsignal(p->p_p->ps_pptr, P_EXITSIG(p)); 410 /* Wake up the parent so it can get exit status. */ 411 wakeup(p->p_p->ps_pptr); 412 } else { 413 /* Noone will wait for us. Just zap the process now */ 414 proc_zap(p); 415 } 416 417 KERNEL_UNLOCK(); 418 } 419 } 420 421 int 422 sys_wait4(struct proc *q, void *v, register_t *retval) 423 { 424 struct sys_wait4_args /* { 425 syscallarg(pid_t) pid; 426 syscallarg(int *) status; 427 syscallarg(int) options; 428 syscallarg(struct rusage *) rusage; 429 } */ *uap = v; 430 int nfound; 431 struct process *pr; 432 struct proc *p; 433 int status, error; 434 435 if (SCARG(uap, pid) == 0) 436 SCARG(uap, pid) = -q->p_p->ps_pgid; 437 if (SCARG(uap, options) &~ (WUNTRACED|WNOHANG|WALTSIG|WCONTINUED)) 438 return (EINVAL); 439 440 loop: 441 nfound = 0; 442 LIST_FOREACH(pr, &q->p_p->ps_children, ps_sibling) { 443 p = pr->ps_mainproc; 444 if ((p->p_flag & P_NOZOMBIE) || 445 (SCARG(uap, pid) != WAIT_ANY && 446 p->p_pid != SCARG(uap, pid) && 447 pr->ps_pgid != -SCARG(uap, pid))) 448 continue; 449 450 /* 451 * Wait for processes with p_exitsig != SIGCHLD processes only 452 * if WALTSIG is set; wait for processes with pexitsig == 453 * SIGCHLD only if WALTSIG is clear. 454 */ 455 if ((SCARG(uap, options) & WALTSIG) ? 456 (p->p_exitsig == SIGCHLD) : (P_EXITSIG(p) != SIGCHLD)) 457 continue; 458 459 nfound++; 460 if (p->p_stat == SZOMB) { 461 retval[0] = p->p_pid; 462 463 if (SCARG(uap, status)) { 464 status = p->p_xstat; /* convert to int */ 465 error = copyout(&status, 466 SCARG(uap, status), sizeof(status)); 467 if (error) 468 return (error); 469 } 470 if (SCARG(uap, rusage) && 471 (error = copyout(p->p_ru, 472 SCARG(uap, rusage), sizeof(struct rusage)))) 473 return (error); 474 proc_finish_wait(q, p); 475 return (0); 476 } 477 if (p->p_stat == SSTOP && 478 (p->p_flag & (P_WAITED|P_SUSPSINGLE)) == 0 && 479 (pr->ps_flags & PS_TRACED || 480 SCARG(uap, options) & WUNTRACED)) { 481 atomic_setbits_int(&p->p_flag, P_WAITED); 482 retval[0] = p->p_pid; 483 484 if (SCARG(uap, status)) { 485 status = W_STOPCODE(p->p_xstat); 486 error = copyout(&status, SCARG(uap, status), 487 sizeof(status)); 488 } else 489 error = 0; 490 return (error); 491 } 492 if ((SCARG(uap, options) & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 493 atomic_clearbits_int(&p->p_flag, P_CONTINUED); 494 retval[0] = p->p_pid; 495 496 if (SCARG(uap, status)) { 497 status = _WCONTINUED; 498 error = copyout(&status, SCARG(uap, status), 499 sizeof(status)); 500 } else 501 error = 0; 502 return (error); 503 } 504 } 505 if (nfound == 0) 506 return (ECHILD); 507 if (SCARG(uap, options) & WNOHANG) { 508 retval[0] = 0; 509 return (0); 510 } 511 if ((error = tsleep(q->p_p, PWAIT | PCATCH, "wait", 0)) != 0) 512 return (error); 513 goto loop; 514 } 515 516 void 517 proc_finish_wait(struct proc *waiter, struct proc *p) 518 { 519 struct process *pr, *tr; 520 521 /* 522 * If we got the child via a ptrace 'attach', 523 * we need to give it back to the old parent. 524 */ 525 pr = p->p_p; 526 if ((p->p_flag & P_THREAD) == 0 && pr->ps_oppid && 527 (tr = prfind(pr->ps_oppid))) { 528 atomic_clearbits_int(&pr->ps_flags, PS_TRACED); 529 pr->ps_oppid = 0; 530 proc_reparent(pr, tr); 531 if (p->p_exitsig != 0) 532 prsignal(tr, p->p_exitsig); 533 wakeup(tr); 534 } else { 535 scheduler_wait_hook(waiter, p); 536 p->p_xstat = 0; 537 ruadd(&waiter->p_stats->p_cru, p->p_ru); 538 proc_zap(p); 539 } 540 } 541 542 /* 543 * make process 'parent' the new parent of process 'child'. 544 */ 545 void 546 proc_reparent(struct process *child, struct process *parent) 547 { 548 549 if (child->ps_pptr == parent) 550 return; 551 552 if (parent == initproc->p_p) 553 child->ps_mainproc->p_exitsig = SIGCHLD; 554 555 LIST_REMOVE(child, ps_sibling); 556 LIST_INSERT_HEAD(&parent->ps_children, child, ps_sibling); 557 child->ps_pptr = parent; 558 } 559 560 void 561 proc_zap(struct proc *p) 562 { 563 struct process *pr = p->p_p; 564 565 pool_put(&rusage_pool, p->p_ru); 566 if ((p->p_flag & P_THREAD) == 0 && pr->ps_ptstat) 567 free(pr->ps_ptstat, M_SUBPROC); 568 569 /* 570 * Finally finished with old proc entry. 571 * Unlink it from its process group and free it. 572 */ 573 if ((p->p_flag & P_THREAD) == 0) 574 leavepgrp(pr); 575 LIST_REMOVE(p, p_list); /* off zombproc */ 576 if ((p->p_flag & P_THREAD) == 0) 577 LIST_REMOVE(pr, ps_sibling); 578 579 /* 580 * Decrement the count of procs running with this uid. 581 */ 582 (void)chgproccnt(p->p_cred->p_ruid, -1); 583 584 /* 585 * Release reference to text vnode 586 */ 587 if (p->p_textvp) 588 vrele(p->p_textvp); 589 590 /* 591 * Remove us from our process list, possibly killing the process 592 * in the process (pun intended). 593 */ 594 if (--pr->ps_refcnt == 0) { 595 KASSERT(TAILQ_EMPTY(&pr->ps_threads)); 596 limfree(pr->ps_limit); 597 crfree(pr->ps_cred->pc_ucred); 598 pool_put(&pcred_pool, pr->ps_cred); 599 pool_put(&process_pool, pr); 600 } 601 602 pool_put(&proc_pool, p); 603 nprocs--; 604 } 605