1 /* $OpenBSD: kern_exit.c,v 1.104 2011/12/11 19:42:28 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 pr->ps_mainproc->p_xstat = rv; 144 145 /* 146 * If parent is waiting for us to exit or exec, PS_PPWAIT 147 * is set; we wake up the parent early to avoid deadlock. 148 */ 149 if (pr->ps_flags & PS_PPWAIT) { 150 atomic_clearbits_int(&pr->ps_flags, PS_PPWAIT); 151 atomic_clearbits_int(&pr->ps_pptr->ps_flags, 152 PS_ISPWAIT); 153 wakeup(pr->ps_pptr); 154 } 155 } 156 157 /* unlink ourselves from the active threads */ 158 TAILQ_REMOVE(&pr->ps_threads, p, p_thr_link); 159 if ((p->p_flag & P_THREAD) == 0) { 160 /* main thread gotta wait because it has the pid, et al */ 161 while (! TAILQ_EMPTY(&pr->ps_threads)) 162 tsleep(&pr->ps_threads, PUSER, "thrdeath", 0); 163 } else if (TAILQ_EMPTY(&pr->ps_threads)) 164 wakeup(&pr->ps_threads); 165 166 if (p->p_flag & P_PROFIL) 167 stopprofclock(p); 168 p->p_ru = pool_get(&rusage_pool, PR_WAITOK); 169 p->p_siglist = 0; 170 timeout_del(&p->p_realit_to); 171 timeout_del(&p->p_stats->p_virt_to); 172 timeout_del(&p->p_stats->p_prof_to); 173 174 /* 175 * Close open files and release open-file table. 176 */ 177 fdfree(p); 178 179 if ((p->p_flag & P_THREAD) == 0) { 180 #ifdef SYSVSEM 181 semexit(pr); 182 #endif 183 if (SESS_LEADER(pr)) { 184 struct session *sp = pr->ps_session; 185 186 if (sp->s_ttyvp) { 187 /* 188 * Controlling process. 189 * Signal foreground pgrp, 190 * drain controlling terminal 191 * and revoke access to controlling terminal. 192 */ 193 if (sp->s_ttyp->t_session == sp) { 194 if (sp->s_ttyp->t_pgrp) 195 pgsignal(sp->s_ttyp->t_pgrp, 196 SIGHUP, 1); 197 (void) ttywait(sp->s_ttyp); 198 /* 199 * The tty could have been revoked 200 * if we blocked. 201 */ 202 if (sp->s_ttyvp) 203 VOP_REVOKE(sp->s_ttyvp, 204 REVOKEALL); 205 } 206 if (sp->s_ttyvp) 207 vrele(sp->s_ttyvp); 208 sp->s_ttyvp = NULL; 209 /* 210 * s_ttyp is not zero'd; we use this to 211 * indicate that the session once had a 212 * controlling terminal. (for logging and 213 * informational purposes) 214 */ 215 } 216 sp->s_leader = NULL; 217 } 218 fixjobc(pr, pr->ps_pgrp, 0); 219 220 #ifdef ACCOUNTING 221 (void)acct_process(p); 222 #endif 223 } 224 225 #ifdef KTRACE 226 /* 227 * release trace file 228 */ 229 p->p_traceflag = 0; /* don't trace the vrele() */ 230 if (p->p_tracep) 231 ktrsettracevnode(p, NULL); 232 #endif 233 #if NSYSTRACE > 0 234 if (ISSET(p->p_flag, P_SYSTRACE)) 235 systrace_exit(p); 236 #endif 237 /* 238 * Remove proc from pidhash chain so looking it up won't 239 * work. Move it from allproc to zombproc, but do not yet 240 * wake up the reaper. We will put the proc on the 241 * deadproc list later (using the p_hash member), and 242 * wake up the reaper when we do. 243 */ 244 /* 245 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 246 */ 247 p->p_stat = SDEAD; 248 249 LIST_REMOVE(p, p_hash); 250 LIST_REMOVE(p, p_list); 251 LIST_INSERT_HEAD(&zombproc, p, p_list); 252 253 /* 254 * Give orphaned children to init(8). 255 */ 256 if ((p->p_flag & P_THREAD) == 0) { 257 qr = LIST_FIRST(&pr->ps_children); 258 if (qr) /* only need this if any child is S_ZOMB */ 259 wakeup(initproc->p_p); 260 for (; qr != 0; qr = nqr) { 261 nqr = LIST_NEXT(qr, ps_sibling); 262 proc_reparent(qr, initproc->p_p); 263 /* 264 * Traced processes are killed 265 * since their existence means someone is screwing up. 266 */ 267 if (qr->ps_mainproc->p_flag & P_TRACED) { 268 atomic_clearbits_int(&qr->ps_mainproc->p_flag, 269 P_TRACED); 270 prsignal(qr, SIGKILL); 271 } 272 } 273 } 274 275 276 /* 277 * Save exit status and final rusage info, adding in child rusage 278 * info and self times. 279 */ 280 *p->p_ru = p->p_stats->p_ru; 281 calcru(p, &p->p_ru->ru_utime, &p->p_ru->ru_stime, NULL); 282 ruadd(p->p_ru, &p->p_stats->p_cru); 283 284 /* 285 * clear %cpu usage during swap 286 */ 287 p->p_pctcpu = 0; 288 289 if ((p->p_flag & P_THREAD) == 0) { 290 /* notify interested parties of our demise and clean up */ 291 knote_processexit(pr); 292 293 /* 294 * Notify parent that we're gone. If we have P_NOZOMBIE 295 * or parent has the SAS_NOCLDWAIT flag set, notify process 1 296 * instead (and hope it will handle this situation). 297 */ 298 if ((p->p_flag & P_NOZOMBIE) || 299 (pr->ps_pptr->ps_mainproc->p_sigacts->ps_flags & 300 SAS_NOCLDWAIT)) { 301 struct process *ppr = pr->ps_pptr; 302 proc_reparent(pr, initproc->p_p); 303 /* 304 * If this was the last child of our parent, notify 305 * parent, so in case he was wait(2)ing, he will 306 * continue. 307 */ 308 if (LIST_EMPTY(&ppr->ps_children)) 309 wakeup(ppr); 310 } 311 } 312 313 /* 314 * Release the process's signal state. 315 */ 316 sigactsfree(p); 317 318 /* 319 * Other substructures are freed from reaper and wait(). 320 */ 321 322 /* 323 * If emulation has process exit hook, call it now. 324 */ 325 if (p->p_emul->e_proc_exit) 326 (*p->p_emul->e_proc_exit)(p); 327 328 /* 329 * Finally, call machine-dependent code to switch to a new 330 * context (possibly the idle context). Once we are no longer 331 * using the dead process's vmspace and stack, exit2() will be 332 * called to schedule those resources to be released by the 333 * reaper thread. 334 * 335 * Note that cpu_exit() will end with a call equivalent to 336 * cpu_switch(), finishing our execution (pun intended). 337 */ 338 uvmexp.swtch++; 339 cpu_exit(p); 340 panic("cpu_exit returned"); 341 } 342 343 /* 344 * Locking of this proclist is special; it's accessed in a 345 * critical section of process exit, and thus locking it can't 346 * modify interrupt state. We use a simple spin lock for this 347 * proclist. Processes on this proclist are also on zombproc; 348 * we use the p_hash member to linkup to deadproc. 349 */ 350 struct mutex deadproc_mutex = MUTEX_INITIALIZER(IPL_NONE); 351 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 352 353 /* 354 * We are called from cpu_exit() once it is safe to schedule the 355 * dead process's resources to be freed. 356 * 357 * NOTE: One must be careful with locking in this routine. It's 358 * called from a critical section in machine-dependent code, so 359 * we should refrain from changing any interrupt state. 360 * 361 * We lock the deadproc list, place the proc on that list (using 362 * the p_hash member), and wake up the reaper. 363 */ 364 void 365 exit2(struct proc *p) 366 { 367 mtx_enter(&deadproc_mutex); 368 LIST_INSERT_HEAD(&deadproc, p, p_hash); 369 mtx_leave(&deadproc_mutex); 370 371 wakeup(&deadproc); 372 } 373 374 /* 375 * Process reaper. This is run by a kernel thread to free the resources 376 * of a dead process. Once the resources are free, the process becomes 377 * a zombie, and the parent is allowed to read the undead's status. 378 */ 379 void 380 reaper(void) 381 { 382 struct proc *p; 383 384 KERNEL_UNLOCK(); 385 386 SCHED_ASSERT_UNLOCKED(); 387 388 for (;;) { 389 mtx_enter(&deadproc_mutex); 390 while ((p = LIST_FIRST(&deadproc)) == NULL) 391 msleep(&deadproc, &deadproc_mutex, PVM, "reaper", 0); 392 393 /* Remove us from the deadproc list. */ 394 LIST_REMOVE(p, p_hash); 395 mtx_leave(&deadproc_mutex); 396 397 KERNEL_LOCK(); 398 399 /* 400 * Free the VM resources we're still holding on to. 401 * We must do this from a valid thread because doing 402 * so may block. 403 */ 404 uvm_exit(p); 405 406 /* Process is now a true zombie. */ 407 if ((p->p_flag & P_NOZOMBIE) == 0) { 408 p->p_stat = SZOMB; 409 410 if (P_EXITSIG(p) != 0) 411 prsignal(p->p_p->ps_pptr, P_EXITSIG(p)); 412 /* Wake up the parent so it can get exit status. */ 413 wakeup(p->p_p->ps_pptr); 414 } else { 415 /* Noone will wait for us. Just zap the process now */ 416 proc_zap(p); 417 } 418 419 KERNEL_UNLOCK(); 420 } 421 } 422 423 int 424 sys_wait4(struct proc *q, void *v, register_t *retval) 425 { 426 struct sys_wait4_args /* { 427 syscallarg(pid_t) pid; 428 syscallarg(int *) status; 429 syscallarg(int) options; 430 syscallarg(struct rusage *) rusage; 431 } */ *uap = v; 432 int nfound; 433 struct process *pr; 434 struct proc *p; 435 int status, error; 436 437 if (SCARG(uap, pid) == 0) 438 SCARG(uap, pid) = -q->p_p->ps_pgid; 439 if (SCARG(uap, options) &~ (WUNTRACED|WNOHANG|WALTSIG|WCONTINUED)) 440 return (EINVAL); 441 442 loop: 443 nfound = 0; 444 LIST_FOREACH(pr, &q->p_p->ps_children, ps_sibling) { 445 p = pr->ps_mainproc; 446 if ((p->p_flag & P_NOZOMBIE) || 447 (SCARG(uap, pid) != WAIT_ANY && 448 p->p_pid != SCARG(uap, pid) && 449 pr->ps_pgid != -SCARG(uap, pid))) 450 continue; 451 452 /* 453 * Wait for processes with p_exitsig != SIGCHLD processes only 454 * if WALTSIG is set; wait for processes with pexitsig == 455 * SIGCHLD only if WALTSIG is clear. 456 */ 457 if ((SCARG(uap, options) & WALTSIG) ? 458 (p->p_exitsig == SIGCHLD) : (P_EXITSIG(p) != SIGCHLD)) 459 continue; 460 461 nfound++; 462 if (p->p_stat == SZOMB) { 463 retval[0] = p->p_pid; 464 465 if (SCARG(uap, status)) { 466 status = p->p_xstat; /* convert to int */ 467 error = copyout(&status, 468 SCARG(uap, status), sizeof(status)); 469 if (error) 470 return (error); 471 } 472 if (SCARG(uap, rusage) && 473 (error = copyout(p->p_ru, 474 SCARG(uap, rusage), sizeof(struct rusage)))) 475 return (error); 476 proc_finish_wait(q, p); 477 return (0); 478 } 479 if (p->p_stat == SSTOP && 480 (p->p_flag & (P_WAITED|P_SUSPSINGLE)) == 0 && 481 (p->p_flag & P_TRACED || SCARG(uap, options) & WUNTRACED)) { 482 atomic_setbits_int(&p->p_flag, P_WAITED); 483 retval[0] = p->p_pid; 484 485 if (SCARG(uap, status)) { 486 status = W_STOPCODE(p->p_xstat); 487 error = copyout(&status, SCARG(uap, status), 488 sizeof(status)); 489 } else 490 error = 0; 491 return (error); 492 } 493 if ((SCARG(uap, options) & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 494 atomic_clearbits_int(&p->p_flag, P_CONTINUED); 495 retval[0] = p->p_pid; 496 497 if (SCARG(uap, status)) { 498 status = _WCONTINUED; 499 error = copyout(&status, SCARG(uap, status), 500 sizeof(status)); 501 } else 502 error = 0; 503 return (error); 504 } 505 } 506 if (nfound == 0) 507 return (ECHILD); 508 if (SCARG(uap, options) & WNOHANG) { 509 retval[0] = 0; 510 return (0); 511 } 512 if ((error = tsleep(q->p_p, PWAIT | PCATCH, "wait", 0)) != 0) 513 return (error); 514 goto loop; 515 } 516 517 void 518 proc_finish_wait(struct proc *waiter, struct proc *p) 519 { 520 struct process *tr; 521 522 /* 523 * If we got the child via a ptrace 'attach', 524 * we need to give it back to the old parent. 525 */ 526 if (p->p_oppid && (tr = prfind(p->p_oppid))) { 527 atomic_clearbits_int(&p->p_flag, P_TRACED); 528 p->p_oppid = 0; 529 proc_reparent(p->p_p, tr); 530 if (p->p_exitsig != 0) 531 prsignal(tr, p->p_exitsig); 532 wakeup(tr); 533 } else { 534 scheduler_wait_hook(waiter, p); 535 p->p_xstat = 0; 536 ruadd(&waiter->p_stats->p_cru, p->p_ru); 537 proc_zap(p); 538 } 539 } 540 541 /* 542 * make process 'parent' the new parent of process 'child'. 543 */ 544 void 545 proc_reparent(struct process *child, struct process *parent) 546 { 547 548 if (child->ps_pptr == parent) 549 return; 550 551 if (parent == initproc->p_p) 552 child->ps_mainproc->p_exitsig = SIGCHLD; 553 554 LIST_REMOVE(child, ps_sibling); 555 LIST_INSERT_HEAD(&parent->ps_children, child, ps_sibling); 556 child->ps_pptr = parent; 557 } 558 559 void 560 proc_zap(struct proc *p) 561 { 562 struct process *pr = p->p_p; 563 564 pool_put(&rusage_pool, p->p_ru); 565 if (p->p_ptstat) 566 free(p->p_ptstat, M_SUBPROC); 567 568 /* 569 * Finally finished with old proc entry. 570 * Unlink it from its process group and free it. 571 */ 572 if ((p->p_flag & P_THREAD) == 0) 573 leavepgrp(pr); 574 LIST_REMOVE(p, p_list); /* off zombproc */ 575 if ((p->p_flag & P_THREAD) == 0) 576 LIST_REMOVE(pr, ps_sibling); 577 578 /* 579 * Decrement the count of procs running with this uid. 580 */ 581 (void)chgproccnt(p->p_cred->p_ruid, -1); 582 583 /* 584 * Release reference to text vnode 585 */ 586 if (p->p_textvp) 587 vrele(p->p_textvp); 588 589 /* 590 * Remove us from our process list, possibly killing the process 591 * in the process (pun intended). 592 */ 593 if (--pr->ps_refcnt == 0) { 594 KASSERT(TAILQ_EMPTY(&pr->ps_threads)); 595 limfree(pr->ps_limit); 596 crfree(pr->ps_cred->pc_ucred); 597 pool_put(&pcred_pool, pr->ps_cred); 598 pool_put(&process_pool, pr); 599 } 600 601 pool_put(&proc_pool, p); 602 nprocs--; 603 } 604