1 /* $OpenBSD: kern_exit.c,v 1.63 2007/03/15 10:22:30 art 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 SYSVSHM 64 #include <sys/shm.h> 65 #endif 66 #ifdef SYSVSEM 67 #include <sys/sem.h> 68 #endif 69 70 #include "systrace.h" 71 #include <dev/systrace.h> 72 73 #include <sys/mount.h> 74 #include <sys/syscallargs.h> 75 76 #include <machine/cpu.h> 77 78 #include <uvm/uvm_extern.h> 79 80 /* 81 * exit -- 82 * Death of process. 83 */ 84 int 85 sys_exit(struct proc *p, void *v, register_t *retval) 86 { 87 struct sys_exit_args /* { 88 syscallarg(int) rval; 89 } */ *uap = v; 90 91 exit1(p, W_EXITCODE(SCARG(uap, rval), 0), EXIT_NORMAL); 92 /* NOTREACHED */ 93 return (0); 94 } 95 96 #ifdef RTHREADS 97 int 98 sys_threxit(struct proc *p, void *v, register_t *retval) 99 { 100 struct sys_threxit_args *uap = v; 101 102 exit1(p, W_EXITCODE(SCARG(uap, rval), 0), EXIT_THREAD); 103 104 return (0); 105 } 106 #endif 107 108 /* 109 * Exit: deallocate address space and other resources, change proc state 110 * to zombie, and unlink proc from allproc and parent's lists. Save exit 111 * status and rusage for wait(). Check for child processes and orphan them. 112 */ 113 void 114 exit1(struct proc *p, int rv, int flags) 115 { 116 struct proc *q, *nq; 117 118 if (p->p_pid == 1) 119 panic("init died (signal %d, exit %d)", 120 WTERMSIG(rv), WEXITSTATUS(rv)); 121 122 #ifdef RTHREADS 123 /* 124 * if one thread calls exit, we take down everybody. 125 * we have to be careful not to get recursively caught. 126 * this is kinda sick. 127 */ 128 if (flags == EXIT_NORMAL && p != p->p_thrparent && 129 (p->p_thrparent->p_flag & P_WEXIT) == 0) { 130 /* 131 * we are one of the threads. we SIGKILL the parent, 132 * it will wake us up again, then we proceed. 133 */ 134 atomic_setbits_int(&p->p_thrparent->p_flag, P_IGNEXITRV); 135 p->p_thrparent->p_xstat = rv; 136 psignal(p->p_thrparent, SIGKILL); 137 tsleep(&p->p_thrparent->p_thrchildren, PUSER, "thrdying", 0); 138 } else if (p == p->p_thrparent) { 139 atomic_setbits_int(&p->p_flag, P_WEXIT); 140 if (flags == EXIT_NORMAL) { 141 q = LIST_FIRST(&p->p_thrchildren); 142 for (; q != NULL; q = nq) { 143 nq = LIST_NEXT(q, p_thrsib); 144 atomic_setbits_int(&q->p_flag, P_IGNEXITRV); 145 q->p_xstat = rv; 146 psignal(q, SIGKILL); 147 } 148 } 149 wakeup(&p->p_thrchildren); 150 while (!LIST_EMPTY(&p->p_thrchildren)) 151 tsleep(&p->p_thrchildren, PUSER, "thrdeath", 0); 152 } 153 #endif 154 155 if (p->p_flag & P_PROFIL) 156 stopprofclock(p); 157 p->p_ru = pool_get(&rusage_pool, PR_WAITOK); 158 /* 159 * If parent is waiting for us to exit or exec, P_PPWAIT is set; we 160 * wake up the parent early to avoid deadlock. 161 */ 162 atomic_setbits_int(&p->p_flag, P_WEXIT); 163 atomic_clearbits_int(&p->p_flag, P_TRACED); 164 if (p->p_flag & P_PPWAIT) { 165 atomic_clearbits_int(&p->p_flag, P_PPWAIT); 166 wakeup(p->p_pptr); 167 } 168 p->p_sigignore = ~0; 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 * This may block! 177 */ 178 fdfree(p); 179 180 #ifdef SYSVSEM 181 semexit(p); 182 #endif 183 if (SESS_LEADER(p)) { 184 struct session *sp = p->p_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, SIGHUP, 1); 196 (void) ttywait(sp->s_ttyp); 197 /* 198 * The tty could have been revoked 199 * if we blocked. 200 */ 201 if (sp->s_ttyvp) 202 VOP_REVOKE(sp->s_ttyvp, REVOKEALL); 203 } 204 if (sp->s_ttyvp) 205 vrele(sp->s_ttyvp); 206 sp->s_ttyvp = NULL; 207 /* 208 * s_ttyp is not zero'd; we use this to indicate 209 * that the session once had a controlling terminal. 210 * (for logging and informational purposes) 211 */ 212 } 213 sp->s_leader = NULL; 214 } 215 fixjobc(p, p->p_pgrp, 0); 216 #ifdef ACCOUNTING 217 (void)acct_process(p); 218 #endif 219 #ifdef KTRACE 220 /* 221 * release trace file 222 */ 223 p->p_traceflag = 0; /* don't trace the vrele() */ 224 if (p->p_tracep) 225 ktrsettracevnode(p, NULL); 226 #endif 227 #if NSYSTRACE > 0 228 if (ISSET(p->p_flag, P_SYSTRACE)) 229 systrace_exit(p); 230 #endif 231 /* 232 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 233 */ 234 p->p_stat = SDEAD; 235 236 /* 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 LIST_REMOVE(p, p_hash); 244 LIST_REMOVE(p, p_list); 245 LIST_INSERT_HEAD(&zombproc, p, p_list); 246 247 /* 248 * Give orphaned children to init(8). 249 */ 250 q = LIST_FIRST(&p->p_children); 251 if (q) /* only need this if any child is S_ZOMB */ 252 wakeup(initproc); 253 for (; q != 0; q = nq) { 254 nq = LIST_NEXT(q, p_sibling); 255 proc_reparent(q, initproc); 256 /* 257 * Traced processes are killed 258 * since their existence means someone is screwing up. 259 */ 260 if (q->p_flag & P_TRACED) { 261 atomic_clearbits_int(&q->p_flag, P_TRACED); 262 psignal(q, SIGKILL); 263 } 264 } 265 266 #ifdef RTHREADS 267 /* unlink oursleves from the active threads */ 268 if (p != p->p_thrparent) { 269 LIST_REMOVE(p, p_thrsib); 270 if (LIST_EMPTY(&p->p_thrparent->p_thrchildren)) 271 wakeup(&p->p_thrparent->p_thrchildren); 272 } 273 #endif 274 275 /* 276 * Save exit status and final rusage info, adding in child rusage 277 * info and self times. 278 */ 279 if (!(p->p_flag & P_IGNEXITRV)) 280 p->p_xstat = rv; 281 *p->p_ru = p->p_stats->p_ru; 282 calcru(p, &p->p_ru->ru_utime, &p->p_ru->ru_stime, NULL); 283 ruadd(p->p_ru, &p->p_stats->p_cru); 284 285 /* 286 * clear %cpu usage during swap 287 */ 288 p->p_pctcpu = 0; 289 290 /* 291 * notify interested parties of our demise. 292 */ 293 KNOTE(&p->p_klist, NOTE_EXIT); 294 295 /* 296 * Notify parent that we're gone. If we have P_NOZOMBIE or parent has 297 * the P_NOCLDWAIT flag set, notify process 1 instead (and hope it 298 * will handle this situation). 299 */ 300 if ((p->p_flag & P_NOZOMBIE) || (p->p_pptr->p_flag & P_NOCLDWAIT)) { 301 struct proc *pp = p->p_pptr; 302 proc_reparent(p, initproc); 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(&pp->p_children)) 309 wakeup(pp); 310 } 311 312 if (p->p_exitsig != 0) 313 psignal(p->p_pptr, P_EXITSIG(p)); 314 wakeup(p->p_pptr); 315 316 /* 317 * Release the process's signal state. 318 */ 319 sigactsfree(p); 320 321 /* 322 * Clear curproc after we've done all operations 323 * that could block, and before tearing down the rest 324 * of the process state that might be used from clock, etc. 325 * Also, can't clear curproc while we're still runnable, 326 * as we're not on a run queue (we are current, just not 327 * a proper proc any longer!). 328 * 329 * Other substructures are freed from wait(). 330 */ 331 curproc = NULL; 332 limfree(p->p_limit); 333 p->p_limit = NULL; 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 /* This process no longer needs to hold the kernel lock. */ 342 KERNEL_PROC_UNLOCK(p); 343 344 /* 345 * Finally, call machine-dependent code to switch to a new 346 * context (possibly the idle context). Once we are no longer 347 * using the dead process's vmspace and stack, exit2() will be 348 * called to schedule those resources to be released by the 349 * reaper thread. 350 * 351 * Note that cpu_exit() will end with a call equivalent to 352 * cpu_switch(), finishing our execution (pun intended). 353 */ 354 uvmexp.swtch++; 355 cpu_exit(p); 356 } 357 358 /* 359 * Locking of this proclist is special; it's accessed in a 360 * critical section of process exit, and thus locking it can't 361 * modify interrupt state. We use a simple spin lock for this 362 * proclist. Processes on this proclist are also on zombproc; 363 * we use the p_hash member to linkup to deadproc. 364 */ 365 struct mutex deadproc_mutex = MUTEX_INITIALIZER(IPL_NONE); 366 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 367 368 /* 369 * We are called from cpu_exit() once it is safe to schedule the 370 * dead process's resources to be freed. 371 * 372 * NOTE: One must be careful with locking in this routine. It's 373 * called from a critical section in machine-dependent code, so 374 * we should refrain from changing any interrupt state. 375 * 376 * We lock the deadproc list, place the proc on that list (using 377 * the p_hash member), and wake up the reaper. 378 */ 379 void 380 exit2(struct proc *p) 381 { 382 int s; 383 384 mtx_enter(&deadproc_mutex); 385 LIST_INSERT_HEAD(&deadproc, p, p_hash); 386 mtx_leave(&deadproc_mutex); 387 388 wakeup(&deadproc); 389 390 SCHED_LOCK(s); 391 } 392 393 /* 394 * Process reaper. This is run by a kernel thread to free the resources 395 * of a dead process. Once the resources are free, the process becomes 396 * a zombie, and the parent is allowed to read the undead's status. 397 */ 398 void 399 reaper(void) 400 { 401 struct proc *p; 402 403 KERNEL_PROC_UNLOCK(curproc); 404 405 for (;;) { 406 mtx_enter(&deadproc_mutex); 407 p = LIST_FIRST(&deadproc); 408 if (p == NULL) { 409 /* No work for us; go to sleep until someone exits. */ 410 mtx_leave(&deadproc_mutex); 411 (void) tsleep(&deadproc, PVM, "reaper", 0); 412 continue; 413 } 414 415 /* Remove us from the deadproc list. */ 416 LIST_REMOVE(p, p_hash); 417 mtx_leave(&deadproc_mutex); 418 KERNEL_PROC_LOCK(curproc); 419 420 /* 421 * Give machine-dependent code a chance to free any 422 * resources it couldn't free while still running on 423 * that process's context. This must be done before 424 * uvm_exit(), in case these resources are in the PCB. 425 */ 426 cpu_wait(p); 427 428 /* 429 * Free the VM resources we're still holding on to. 430 * We must do this from a valid thread because doing 431 * so may block. 432 */ 433 uvm_exit(p); 434 435 /* Process is now a true zombie. */ 436 if ((p->p_flag & P_NOZOMBIE) == 0) { 437 p->p_stat = SZOMB; 438 439 /* Wake up the parent so it can get exit status. */ 440 psignal(p->p_pptr, SIGCHLD); 441 wakeup(p->p_pptr); 442 } else { 443 /* Noone will wait for us. Just zap the process now */ 444 proc_zap(p); 445 } 446 447 KERNEL_PROC_UNLOCK(curproc); 448 } 449 } 450 451 pid_t 452 sys_wait4(struct proc *q, void *v, register_t *retval) 453 { 454 struct sys_wait4_args /* { 455 syscallarg(pid_t) pid; 456 syscallarg(int *) status; 457 syscallarg(int) options; 458 syscallarg(struct rusage *) rusage; 459 } */ *uap = v; 460 int nfound; 461 struct proc *p, *t; 462 int status, error; 463 464 if (SCARG(uap, pid) == 0) 465 SCARG(uap, pid) = -q->p_pgid; 466 if (SCARG(uap, options) &~ (WUNTRACED|WNOHANG|WALTSIG|WCONTINUED)) 467 return (EINVAL); 468 469 loop: 470 nfound = 0; 471 LIST_FOREACH(p, &q->p_children, p_sibling) { 472 if ((p->p_flag & P_NOZOMBIE) || 473 (SCARG(uap, pid) != WAIT_ANY && 474 p->p_pid != SCARG(uap, pid) && 475 p->p_pgid != -SCARG(uap, pid))) 476 continue; 477 478 /* 479 * Wait for processes with p_exitsig != SIGCHLD processes only 480 * if WALTSIG is set; wait for processes with pexitsig == 481 * SIGCHLD only if WALTSIG is clear. 482 */ 483 if ((SCARG(uap, options) & WALTSIG) ? 484 (p->p_exitsig == SIGCHLD) : (P_EXITSIG(p) != SIGCHLD)) 485 continue; 486 487 nfound++; 488 if (p->p_stat == SZOMB) { 489 retval[0] = p->p_pid; 490 491 if (SCARG(uap, status)) { 492 status = p->p_xstat; /* convert to int */ 493 error = copyout(&status, 494 SCARG(uap, status), sizeof(status)); 495 if (error) 496 return (error); 497 } 498 if (SCARG(uap, rusage) && 499 (error = copyout(p->p_ru, 500 SCARG(uap, rusage), sizeof(struct rusage)))) 501 return (error); 502 503 /* 504 * If we got the child via a ptrace 'attach', 505 * we need to give it back to the old parent. 506 */ 507 if (p->p_oppid && (t = pfind(p->p_oppid))) { 508 p->p_oppid = 0; 509 proc_reparent(p, t); 510 if (p->p_exitsig != 0) 511 psignal(t, P_EXITSIG(p)); 512 wakeup(t); 513 return (0); 514 } 515 516 scheduler_wait_hook(q, p); 517 p->p_xstat = 0; 518 ruadd(&q->p_stats->p_cru, p->p_ru); 519 520 proc_zap(p); 521 522 return (0); 523 } 524 if (p->p_stat == SSTOP && (p->p_flag & P_WAITED) == 0 && 525 (p->p_flag & P_TRACED || SCARG(uap, options) & WUNTRACED)) { 526 atomic_setbits_int(&p->p_flag, P_WAITED); 527 retval[0] = p->p_pid; 528 529 if (SCARG(uap, status)) { 530 status = W_STOPCODE(p->p_xstat); 531 error = copyout(&status, SCARG(uap, status), 532 sizeof(status)); 533 } else 534 error = 0; 535 return (error); 536 } 537 if ((SCARG(uap, options) & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 538 atomic_clearbits_int(&p->p_flag, P_CONTINUED); 539 retval[0] = p->p_pid; 540 541 if (SCARG(uap, status)) { 542 status = _WCONTINUED; 543 error = copyout(&status, SCARG(uap, status), 544 sizeof(status)); 545 } else 546 error = 0; 547 return (error); 548 } 549 } 550 if (nfound == 0) 551 return (ECHILD); 552 if (SCARG(uap, options) & WNOHANG) { 553 retval[0] = 0; 554 return (0); 555 } 556 if ((error = tsleep(q, PWAIT | PCATCH, "wait", 0)) != 0) 557 return (error); 558 goto loop; 559 } 560 561 /* 562 * make process 'parent' the new parent of process 'child'. 563 */ 564 void 565 proc_reparent(struct proc *child, struct proc *parent) 566 { 567 568 if (child->p_pptr == parent) 569 return; 570 571 if (parent == initproc) 572 child->p_exitsig = SIGCHLD; 573 574 LIST_REMOVE(child, p_sibling); 575 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); 576 child->p_pptr = parent; 577 } 578 579 void 580 proc_zap(struct proc *p) 581 { 582 pool_put(&rusage_pool, p->p_ru); 583 if (p->p_ptstat) 584 free(p->p_ptstat, M_SUBPROC); 585 586 /* 587 * Finally finished with old proc entry. 588 * Unlink it from its process group and free it. 589 */ 590 leavepgrp(p); 591 LIST_REMOVE(p, p_list); /* off zombproc */ 592 LIST_REMOVE(p, p_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 * Free up credentials. 601 */ 602 if (--p->p_cred->p_refcnt == 0) { 603 crfree(p->p_cred->pc_ucred); 604 pool_put(&pcred_pool, p->p_cred); 605 } 606 607 /* 608 * Release reference to text vnode 609 */ 610 if (p->p_textvp) 611 vrele(p->p_textvp); 612 613 pool_put(&proc_pool, p); 614 nprocs--; 615 } 616 617