1 /* $OpenBSD: kern_exit.c,v 1.52 2004/07/22 15:42:11 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(p, v, retval) 86 struct proc *p; 87 void *v; 88 register_t *retval; 89 { 90 struct sys_exit_args /* { 91 syscallarg(int) rval; 92 } */ *uap = v; 93 94 exit1(p, W_EXITCODE(SCARG(uap, rval), 0)); 95 /* NOTREACHED */ 96 return (0); 97 } 98 99 /* 100 * Exit: deallocate address space and other resources, change proc state 101 * to zombie, and unlink proc from allproc and parent's lists. Save exit 102 * status and rusage for wait(). Check for child processes and orphan them. 103 */ 104 void 105 exit1(p, rv) 106 struct proc *p; 107 int rv; 108 { 109 struct proc *q, *nq; 110 111 if (p->p_pid == 1) 112 panic("init died (signal %d, exit %d)", 113 WTERMSIG(rv), WEXITSTATUS(rv)); 114 115 if (p->p_flag & P_PROFIL) 116 stopprofclock(p); 117 p->p_ru = pool_get(&rusage_pool, PR_WAITOK); 118 /* 119 * If parent is waiting for us to exit or exec, P_PPWAIT is set; we 120 * wake up the parent early to avoid deadlock. 121 */ 122 p->p_flag |= P_WEXIT; 123 p->p_flag &= ~P_TRACED; 124 if (p->p_flag & P_PPWAIT) { 125 p->p_flag &= ~P_PPWAIT; 126 wakeup(p->p_pptr); 127 } 128 p->p_sigignore = ~0; 129 p->p_siglist = 0; 130 timeout_del(&p->p_realit_to); 131 132 /* 133 * Close open files and release open-file table. 134 * This may block! 135 */ 136 fdfree(p); 137 138 #ifdef SYSVSEM 139 semexit(p); 140 #endif 141 if (SESS_LEADER(p)) { 142 register struct session *sp = p->p_session; 143 144 if (sp->s_ttyvp) { 145 /* 146 * Controlling process. 147 * Signal foreground pgrp, 148 * drain controlling terminal 149 * and revoke access to controlling terminal. 150 */ 151 if (sp->s_ttyp->t_session == sp) { 152 if (sp->s_ttyp->t_pgrp) 153 pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1); 154 (void) ttywait(sp->s_ttyp); 155 /* 156 * The tty could have been revoked 157 * if we blocked. 158 */ 159 if (sp->s_ttyvp) 160 VOP_REVOKE(sp->s_ttyvp, REVOKEALL); 161 } 162 if (sp->s_ttyvp) 163 vrele(sp->s_ttyvp); 164 sp->s_ttyvp = NULL; 165 /* 166 * s_ttyp is not zero'd; we use this to indicate 167 * that the session once had a controlling terminal. 168 * (for logging and informational purposes) 169 */ 170 } 171 sp->s_leader = NULL; 172 } 173 fixjobc(p, p->p_pgrp, 0); 174 #ifdef ACCOUNTING 175 (void)acct_process(p); 176 #endif 177 #ifdef KTRACE 178 /* 179 * release trace file 180 */ 181 p->p_traceflag = 0; /* don't trace the vrele() */ 182 if (p->p_tracep) 183 ktrsettracevnode(p, NULL); 184 #endif 185 #if NSYSTRACE > 0 186 if (ISSET(p->p_flag, P_SYSTRACE)) 187 systrace_exit(p); 188 #endif 189 /* 190 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 191 */ 192 p->p_stat = SDEAD; 193 194 /* 195 * Remove proc from pidhash chain so looking it up won't 196 * work. Move it from allproc to zombproc, but do not yet 197 * wake up the reaper. We will put the proc on the 198 * deadproc list later (using the p_hash member), and 199 * wake up the reaper when we do. 200 */ 201 LIST_REMOVE(p, p_hash); 202 LIST_REMOVE(p, p_list); 203 LIST_INSERT_HEAD(&zombproc, p, p_list); 204 205 /* 206 * Give orphaned children to init(8). 207 */ 208 q = p->p_children.lh_first; 209 if (q) /* only need this if any child is S_ZOMB */ 210 wakeup(initproc); 211 for (; q != 0; q = nq) { 212 nq = q->p_sibling.le_next; 213 proc_reparent(q, initproc); 214 /* 215 * Traced processes are killed 216 * since their existence means someone is screwing up. 217 */ 218 if (q->p_flag & P_TRACED) { 219 q->p_flag &= ~P_TRACED; 220 psignal(q, SIGKILL); 221 } 222 } 223 224 /* 225 * Save exit status and final rusage info, adding in child rusage 226 * info and self times. 227 */ 228 p->p_xstat = rv; 229 *p->p_ru = p->p_stats->p_ru; 230 calcru(p, &p->p_ru->ru_utime, &p->p_ru->ru_stime, NULL); 231 ruadd(p->p_ru, &p->p_stats->p_cru); 232 233 /* 234 * clear %cpu usage during swap 235 */ 236 p->p_pctcpu = 0; 237 238 /* 239 * notify interested parties of our demise. 240 */ 241 KNOTE(&p->p_klist, NOTE_EXIT); 242 243 /* 244 * Notify parent that we're gone. If we have P_NOZOMBIE or parent has 245 * the P_NOCLDWAIT flag set, notify process 1 instead (and hope it 246 * will handle this situation). 247 */ 248 if ((p->p_flag & P_NOZOMBIE) || (p->p_pptr->p_flag & P_NOCLDWAIT)) { 249 struct proc *pp = p->p_pptr; 250 proc_reparent(p, initproc); 251 /* 252 * If this was the last child of our parent, notify 253 * parent, so in case he was wait(2)ing, he will 254 * continue. 255 */ 256 if (pp->p_children.lh_first == NULL) 257 wakeup(pp); 258 } 259 260 if ((p->p_flag & P_FSTRACE) == 0 && p->p_exitsig != 0) 261 psignal(p->p_pptr, P_EXITSIG(p)); 262 wakeup(p->p_pptr); 263 264 /* 265 * Notify procfs debugger 266 */ 267 if (p->p_flag & P_FSTRACE) 268 wakeup(p); 269 270 /* 271 * Release the process's signal state. 272 */ 273 sigactsfree(p); 274 275 /* 276 * Clear curproc after we've done all operations 277 * that could block, and before tearing down the rest 278 * of the process state that might be used from clock, etc. 279 * Also, can't clear curproc while we're still runnable, 280 * as we're not on a run queue (we are current, just not 281 * a proper proc any longer!). 282 * 283 * Other substructures are freed from wait(). 284 */ 285 curproc = NULL; 286 limfree(p->p_limit); 287 p->p_limit = NULL; 288 289 /* This process no longer needs to hold the kernel lock. */ 290 KERNEL_PROC_UNLOCK(p); 291 292 /* 293 * If emulation has process exit hook, call it now. 294 */ 295 if (p->p_emul->e_proc_exit) 296 (*p->p_emul->e_proc_exit)(p); 297 298 /* 299 * Finally, call machine-dependent code to switch to a new 300 * context (possibly the idle context). Once we are no longer 301 * using the dead process's vmspace and stack, exit2() will be 302 * called to schedule those resources to be released by the 303 * reaper thread. 304 * 305 * Note that cpu_exit() will end with a call equivalent to 306 * cpu_switch(), finishing our execution (pun intended). 307 */ 308 cpu_exit(p); 309 } 310 311 /* 312 * Locking of this proclist is special; it's accessed in a 313 * critical section of process exit, and thus locking it can't 314 * modify interrupt state. We use a simple spin lock for this 315 * proclist. Processes on this proclist are also on zombproc; 316 * we use the p_hash member to linkup to deadproc. 317 */ 318 struct mutex deadproc_mutex = MUTEX_INITIALIZER(IPL_NONE); 319 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 320 321 /* 322 * We are called from cpu_exit() once it is safe to schedule the 323 * dead process's resources to be freed. 324 * 325 * NOTE: One must be careful with locking in this routine. It's 326 * called from a critical section in machine-dependent code, so 327 * we should refrain from changing any interrupt state. 328 * 329 * We lock the deadproc list, place the proc on that list (using 330 * the p_hash member), and wake up the reaper. 331 */ 332 void 333 exit2(struct proc *p) 334 { 335 int s; 336 337 mtx_enter(&deadproc_mutex); 338 LIST_INSERT_HEAD(&deadproc, p, p_hash); 339 mtx_leave(&deadproc_mutex); 340 341 wakeup(&deadproc); 342 343 SCHED_LOCK(s); 344 } 345 346 /* 347 * Process reaper. This is run by a kernel thread to free the resources 348 * of a dead process. Once the resources are free, the process becomes 349 * a zombie, and the parent is allowed to read the undead's status. 350 */ 351 void 352 reaper(void) 353 { 354 struct proc *p; 355 356 KERNEL_PROC_UNLOCK(curproc); 357 358 for (;;) { 359 mtx_enter(&deadproc_mutex); 360 p = LIST_FIRST(&deadproc); 361 if (p == NULL) { 362 /* No work for us; go to sleep until someone exits. */ 363 mtx_leave(&deadproc_mutex); 364 (void) tsleep(&deadproc, PVM, "reaper", 0); 365 continue; 366 } 367 368 /* Remove us from the deadproc list. */ 369 LIST_REMOVE(p, p_hash); 370 mtx_leave(&deadproc_mutex); 371 KERNEL_PROC_LOCK(curproc); 372 373 /* 374 * Give machine-dependent code a chance to free any 375 * resources it couldn't free while still running on 376 * that process's context. This must be done before 377 * uvm_exit(), in case these resources are in the PCB. 378 */ 379 cpu_wait(p); 380 381 /* 382 * Free the VM resources we're still holding on to. 383 * We must do this from a valid thread because doing 384 * so may block. 385 */ 386 uvm_exit(p); 387 388 /* Process is now a true zombie. */ 389 if ((p->p_flag & P_NOZOMBIE) == 0) { 390 p->p_stat = SZOMB; 391 392 /* Wake up the parent so it can get exit status. */ 393 psignal(p->p_pptr, SIGCHLD); 394 wakeup(p->p_pptr); 395 } else { 396 /* Noone will wait for us. Just zap the process now */ 397 proc_zap(p); 398 } 399 400 KERNEL_PROC_UNLOCK(curproc); 401 } 402 } 403 404 pid_t 405 sys_wait4(q, v, retval) 406 register struct proc *q; 407 void *v; 408 register_t *retval; 409 { 410 register struct sys_wait4_args /* { 411 syscallarg(pid_t) pid; 412 syscallarg(int *) status; 413 syscallarg(int) options; 414 syscallarg(struct rusage *) rusage; 415 } */ *uap = v; 416 register int nfound; 417 register struct proc *p, *t; 418 int status, error; 419 420 if (SCARG(uap, pid) == 0) 421 SCARG(uap, pid) = -q->p_pgid; 422 if (SCARG(uap, options) &~ (WUNTRACED|WNOHANG|WALTSIG|WCONTINUED)) 423 return (EINVAL); 424 425 loop: 426 nfound = 0; 427 for (p = q->p_children.lh_first; p != 0; p = p->p_sibling.le_next) { 428 if ((p->p_flag & P_NOZOMBIE) || 429 (SCARG(uap, pid) != WAIT_ANY && 430 p->p_pid != SCARG(uap, pid) && 431 p->p_pgid != -SCARG(uap, pid))) 432 continue; 433 434 /* 435 * Wait for processes with p_exitsig != SIGCHLD processes only 436 * if WALTSIG is set; wait for processes with pexitsig == 437 * SIGCHLD only if WALTSIG is clear. 438 */ 439 if ((SCARG(uap, options) & WALTSIG) ? 440 (p->p_exitsig == SIGCHLD) : (P_EXITSIG(p) != SIGCHLD)) 441 continue; 442 443 nfound++; 444 if (p->p_stat == SZOMB) { 445 retval[0] = p->p_pid; 446 447 if (SCARG(uap, status)) { 448 status = p->p_xstat; /* convert to int */ 449 error = copyout(&status, 450 SCARG(uap, status), sizeof(status)); 451 if (error) 452 return (error); 453 } 454 if (SCARG(uap, rusage) && 455 (error = copyout(p->p_ru, 456 SCARG(uap, rusage), sizeof(struct rusage)))) 457 return (error); 458 459 /* 460 * If we got the child via a ptrace 'attach', 461 * we need to give it back to the old parent. 462 */ 463 if (p->p_oppid && (t = pfind(p->p_oppid))) { 464 p->p_oppid = 0; 465 proc_reparent(p, t); 466 if (p->p_exitsig != 0) 467 psignal(t, P_EXITSIG(p)); 468 wakeup(t); 469 return (0); 470 } 471 472 scheduler_wait_hook(q, p); 473 p->p_xstat = 0; 474 ruadd(&q->p_stats->p_cru, p->p_ru); 475 476 proc_zap(p); 477 478 return (0); 479 } 480 if (p->p_stat == SSTOP && (p->p_flag & P_WAITED) == 0 && 481 (p->p_flag & P_TRACED || SCARG(uap, options) & WUNTRACED)) { 482 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 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, PWAIT | PCATCH, "wait", 0)) != 0) 513 return (error); 514 goto loop; 515 } 516 517 /* 518 * make process 'parent' the new parent of process 'child'. 519 */ 520 void 521 proc_reparent(child, parent) 522 register struct proc *child; 523 register struct proc *parent; 524 { 525 526 if (child->p_pptr == parent) 527 return; 528 529 if (parent == initproc) 530 child->p_exitsig = SIGCHLD; 531 532 LIST_REMOVE(child, p_sibling); 533 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); 534 child->p_pptr = parent; 535 } 536 537 void 538 proc_zap(struct proc *p) 539 { 540 pool_put(&rusage_pool, p->p_ru); 541 542 /* 543 * Finally finished with old proc entry. 544 * Unlink it from its process group and free it. 545 */ 546 leavepgrp(p); 547 LIST_REMOVE(p, p_list); /* off zombproc */ 548 LIST_REMOVE(p, p_sibling); 549 550 /* 551 * Decrement the count of procs running with this uid. 552 */ 553 (void)chgproccnt(p->p_cred->p_ruid, -1); 554 555 /* 556 * Free up credentials. 557 */ 558 if (--p->p_cred->p_refcnt == 0) { 559 crfree(p->p_cred->pc_ucred); 560 pool_put(&pcred_pool, p->p_cred); 561 } 562 563 /* 564 * Release reference to text vnode 565 */ 566 if (p->p_textvp) 567 vrele(p->p_textvp); 568 569 pool_put(&proc_pool, p); 570 nprocs--; 571 } 572 573