1 /* $OpenBSD: kern_exit.c,v 1.50 2004/05/27 20:48:46 tedu 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 #ifdef SYSVSHM 63 #include <sys/shm.h> 64 #endif 65 #ifdef SYSVSEM 66 #include <sys/sem.h> 67 #endif 68 69 #include "systrace.h" 70 #include <dev/systrace.h> 71 72 #include <sys/mount.h> 73 #include <sys/syscallargs.h> 74 75 #include <machine/cpu.h> 76 77 #include <uvm/uvm_extern.h> 78 79 /* 80 * exit -- 81 * Death of process. 82 */ 83 int 84 sys_exit(p, v, retval) 85 struct proc *p; 86 void *v; 87 register_t *retval; 88 { 89 struct sys_exit_args /* { 90 syscallarg(int) rval; 91 } */ *uap = v; 92 93 exit1(p, W_EXITCODE(SCARG(uap, rval), 0)); 94 /* NOTREACHED */ 95 return (0); 96 } 97 98 /* 99 * Exit: deallocate address space and other resources, change proc state 100 * to zombie, and unlink proc from allproc and parent's lists. Save exit 101 * status and rusage for wait(). Check for child processes and orphan them. 102 */ 103 void 104 exit1(p, rv) 105 struct proc *p; 106 int rv; 107 { 108 struct proc *q, *nq; 109 110 if (p->p_pid == 1) 111 panic("init died (signal %d, exit %d)", 112 WTERMSIG(rv), WEXITSTATUS(rv)); 113 114 if (p->p_flag & P_PROFIL) 115 stopprofclock(p); 116 p->p_ru = pool_get(&rusage_pool, PR_WAITOK); 117 /* 118 * If parent is waiting for us to exit or exec, P_PPWAIT is set; we 119 * wake up the parent early to avoid deadlock. 120 */ 121 p->p_flag |= P_WEXIT; 122 p->p_flag &= ~P_TRACED; 123 if (p->p_flag & P_PPWAIT) { 124 p->p_flag &= ~P_PPWAIT; 125 wakeup(p->p_pptr); 126 } 127 p->p_sigignore = ~0; 128 p->p_siglist = 0; 129 timeout_del(&p->p_realit_to); 130 131 /* 132 * Close open files and release open-file table. 133 * This may block! 134 */ 135 fdfree(p); 136 137 #ifdef SYSVSEM 138 semexit(p); 139 #endif 140 if (SESS_LEADER(p)) { 141 register struct session *sp = p->p_session; 142 143 if (sp->s_ttyvp) { 144 /* 145 * Controlling process. 146 * Signal foreground pgrp, 147 * drain controlling terminal 148 * and revoke access to controlling terminal. 149 */ 150 if (sp->s_ttyp->t_session == sp) { 151 if (sp->s_ttyp->t_pgrp) 152 pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1); 153 (void) ttywait(sp->s_ttyp); 154 /* 155 * The tty could have been revoked 156 * if we blocked. 157 */ 158 if (sp->s_ttyvp) 159 VOP_REVOKE(sp->s_ttyvp, REVOKEALL); 160 } 161 if (sp->s_ttyvp) 162 vrele(sp->s_ttyvp); 163 sp->s_ttyvp = NULL; 164 /* 165 * s_ttyp is not zero'd; we use this to indicate 166 * that the session once had a controlling terminal. 167 * (for logging and informational purposes) 168 */ 169 } 170 sp->s_leader = NULL; 171 } 172 fixjobc(p, p->p_pgrp, 0); 173 #ifdef ACCOUNTING 174 (void)acct_process(p); 175 #endif 176 #ifdef KTRACE 177 /* 178 * release trace file 179 */ 180 p->p_traceflag = 0; /* don't trace the vrele() */ 181 if (p->p_tracep) 182 ktrsettracevnode(p, NULL); 183 #endif 184 #if NSYSTRACE > 0 185 if (ISSET(p->p_flag, P_SYSTRACE)) 186 systrace_exit(p); 187 #endif 188 /* 189 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 190 */ 191 p->p_stat = SDEAD; 192 193 /* 194 * Remove proc from pidhash chain so looking it up won't 195 * work. Move it from allproc to zombproc, but do not yet 196 * wake up the reaper. We will put the proc on the 197 * deadproc list later (using the p_hash member), and 198 * wake up the reaper when we do. 199 */ 200 LIST_REMOVE(p, p_hash); 201 LIST_REMOVE(p, p_list); 202 LIST_INSERT_HEAD(&zombproc, p, p_list); 203 204 /* 205 * Give orphaned children to init(8). 206 */ 207 q = p->p_children.lh_first; 208 if (q) /* only need this if any child is S_ZOMB */ 209 wakeup(initproc); 210 for (; q != 0; q = nq) { 211 nq = q->p_sibling.le_next; 212 proc_reparent(q, initproc); 213 /* 214 * Traced processes are killed 215 * since their existence means someone is screwing up. 216 */ 217 if (q->p_flag & P_TRACED) { 218 q->p_flag &= ~P_TRACED; 219 psignal(q, SIGKILL); 220 } 221 } 222 223 /* 224 * Save exit status and final rusage info, adding in child rusage 225 * info and self times. 226 */ 227 p->p_xstat = rv; 228 *p->p_ru = p->p_stats->p_ru; 229 calcru(p, &p->p_ru->ru_utime, &p->p_ru->ru_stime, NULL); 230 ruadd(p->p_ru, &p->p_stats->p_cru); 231 232 /* 233 * clear %cpu usage during swap 234 */ 235 p->p_pctcpu = 0; 236 237 /* 238 * notify interested parties of our demise. 239 */ 240 KNOTE(&p->p_klist, NOTE_EXIT); 241 242 /* 243 * Notify parent that we're gone. If we have P_NOZOMBIE or parent has 244 * the P_NOCLDWAIT flag set, notify process 1 instead (and hope it 245 * will handle this situation). 246 */ 247 if ((p->p_flag & P_NOZOMBIE) || (p->p_pptr->p_flag & P_NOCLDWAIT)) { 248 struct proc *pp = p->p_pptr; 249 proc_reparent(p, initproc); 250 /* 251 * If this was the last child of our parent, notify 252 * parent, so in case he was wait(2)ing, he will 253 * continue. 254 */ 255 if (pp->p_children.lh_first == NULL) 256 wakeup(pp); 257 } 258 259 if ((p->p_flag & P_FSTRACE) == 0 && p->p_exitsig != 0) 260 psignal(p->p_pptr, P_EXITSIG(p)); 261 wakeup(p->p_pptr); 262 263 /* 264 * Notify procfs debugger 265 */ 266 if (p->p_flag & P_FSTRACE) 267 wakeup(p); 268 269 /* 270 * Release the process's signal state. 271 */ 272 sigactsfree(p); 273 274 /* 275 * Clear curproc after we've done all operations 276 * that could block, and before tearing down the rest 277 * of the process state that might be used from clock, etc. 278 * Also, can't clear curproc while we're still runnable, 279 * as we're not on a run queue (we are current, just not 280 * a proper proc any longer!). 281 * 282 * Other substructures are freed from wait(). 283 */ 284 curproc = NULL; 285 limfree(p->p_limit); 286 p->p_limit = NULL; 287 288 /* 289 * If emulation has process exit hook, call it now. 290 */ 291 if (p->p_emul->e_proc_exit) 292 (*p->p_emul->e_proc_exit)(p); 293 294 /* 295 * Finally, call machine-dependent code to switch to a new 296 * context (possibly the idle context). Once we are no longer 297 * using the dead process's vmspace and stack, exit2() will be 298 * called to schedule those resources to be released by the 299 * reaper thread. 300 * 301 * Note that cpu_exit() will end with a call equivalent to 302 * cpu_switch(), finishing our execution (pun intended). 303 */ 304 cpu_exit(p); 305 } 306 307 /* 308 * We are called from cpu_exit() once it is safe to schedule the 309 * dead process's resources to be freed. 310 * 311 * NOTE: One must be careful with locking in this routine. It's 312 * called from a critical section in machine-dependent code, so 313 * we should refrain from changing any interrupt state. 314 * 315 * We lock the deadproc list (a spin lock), place the proc on that 316 * list (using the p_hash member), and wake up the reaper. 317 */ 318 void 319 exit2(p) 320 struct proc *p; 321 { 322 323 simple_lock(&deadproc_slock); 324 LIST_INSERT_HEAD(&deadproc, p, p_hash); 325 simple_unlock(&deadproc_slock); 326 327 wakeup(&deadproc); 328 } 329 330 /* 331 * Process reaper. This is run by a kernel thread to free the resources 332 * of a dead process. Once the resources are free, the process becomes 333 * a zombie, and the parent is allowed to read the undead's status. 334 */ 335 void 336 reaper(void) 337 { 338 struct proc *p; 339 340 for (;;) { 341 simple_lock(&deadproc_slock); 342 p = LIST_FIRST(&deadproc); 343 if (p == NULL) { 344 /* No work for us; go to sleep until someone exits. */ 345 simple_unlock(&deadproc_slock); 346 (void) tsleep(&deadproc, PVM, "reaper", 0); 347 continue; 348 } 349 350 /* Remove us from the deadproc list. */ 351 LIST_REMOVE(p, p_hash); 352 simple_unlock(&deadproc_slock); 353 354 /* 355 * Give machine-dependent code a chance to free any 356 * resources it couldn't free while still running on 357 * that process's context. This must be done before 358 * uvm_exit(), in case these resources are in the PCB. 359 */ 360 cpu_wait(p); 361 362 /* 363 * Free the VM resources we're still holding on to. 364 * We must do this from a valid thread because doing 365 * so may block. 366 */ 367 uvm_exit(p); 368 369 /* Process is now a true zombie. */ 370 if ((p->p_flag & P_NOZOMBIE) == 0) { 371 p->p_stat = SZOMB; 372 373 /* Wake up the parent so it can get exit status. */ 374 psignal(p->p_pptr, SIGCHLD); 375 wakeup(p->p_pptr); 376 } else { 377 /* Noone will wait for us. Just zap the process now */ 378 proc_zap(p); 379 } 380 } 381 } 382 383 pid_t 384 sys_wait4(q, v, retval) 385 register struct proc *q; 386 void *v; 387 register_t *retval; 388 { 389 register struct sys_wait4_args /* { 390 syscallarg(pid_t) pid; 391 syscallarg(int *) status; 392 syscallarg(int) options; 393 syscallarg(struct rusage *) rusage; 394 } */ *uap = v; 395 register int nfound; 396 register struct proc *p, *t; 397 int status, error; 398 399 if (SCARG(uap, pid) == 0) 400 SCARG(uap, pid) = -q->p_pgid; 401 if (SCARG(uap, options) &~ (WUNTRACED|WNOHANG|WALTSIG|WCONTINUED)) 402 return (EINVAL); 403 404 loop: 405 nfound = 0; 406 for (p = q->p_children.lh_first; p != 0; p = p->p_sibling.le_next) { 407 if ((p->p_flag & P_NOZOMBIE) || 408 (SCARG(uap, pid) != WAIT_ANY && 409 p->p_pid != SCARG(uap, pid) && 410 p->p_pgid != -SCARG(uap, pid))) 411 continue; 412 413 /* 414 * Wait for processes with p_exitsig != SIGCHLD processes only 415 * if WALTSIG is set; wait for processes with pexitsig == 416 * SIGCHLD only if WALTSIG is clear. 417 */ 418 if ((SCARG(uap, options) & WALTSIG) ? 419 (p->p_exitsig == SIGCHLD) : (P_EXITSIG(p) != SIGCHLD)) 420 continue; 421 422 nfound++; 423 if (p->p_stat == SZOMB) { 424 retval[0] = p->p_pid; 425 426 if (SCARG(uap, status)) { 427 status = p->p_xstat; /* convert to int */ 428 error = copyout(&status, 429 SCARG(uap, status), sizeof(status)); 430 if (error) 431 return (error); 432 } 433 if (SCARG(uap, rusage) && 434 (error = copyout(p->p_ru, 435 SCARG(uap, rusage), sizeof(struct rusage)))) 436 return (error); 437 438 /* 439 * If we got the child via a ptrace 'attach', 440 * we need to give it back to the old parent. 441 */ 442 if (p->p_oppid && (t = pfind(p->p_oppid))) { 443 p->p_oppid = 0; 444 proc_reparent(p, t); 445 if (p->p_exitsig != 0) 446 psignal(t, P_EXITSIG(p)); 447 wakeup(t); 448 return (0); 449 } 450 451 scheduler_wait_hook(q, p); 452 p->p_xstat = 0; 453 ruadd(&q->p_stats->p_cru, p->p_ru); 454 455 proc_zap(p); 456 457 return (0); 458 } 459 if (p->p_stat == SSTOP && (p->p_flag & P_WAITED) == 0 && 460 (p->p_flag & P_TRACED || SCARG(uap, options) & WUNTRACED)) { 461 p->p_flag |= P_WAITED; 462 retval[0] = p->p_pid; 463 464 if (SCARG(uap, status)) { 465 status = W_STOPCODE(p->p_xstat); 466 error = copyout(&status, SCARG(uap, status), 467 sizeof(status)); 468 } else 469 error = 0; 470 return (error); 471 } 472 if ((SCARG(uap, options) & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 473 p->p_flag &= ~P_CONTINUED; 474 retval[0] = p->p_pid; 475 476 if (SCARG(uap, status)) { 477 status = _WCONTINUED; 478 error = copyout(&status, SCARG(uap, status), 479 sizeof(status)); 480 } else 481 error = 0; 482 return (error); 483 } 484 } 485 if (nfound == 0) 486 return (ECHILD); 487 if (SCARG(uap, options) & WNOHANG) { 488 retval[0] = 0; 489 return (0); 490 } 491 if ((error = tsleep(q, PWAIT | PCATCH, "wait", 0)) != 0) 492 return (error); 493 goto loop; 494 } 495 496 /* 497 * make process 'parent' the new parent of process 'child'. 498 */ 499 void 500 proc_reparent(child, parent) 501 register struct proc *child; 502 register struct proc *parent; 503 { 504 505 if (child->p_pptr == parent) 506 return; 507 508 if (parent == initproc) 509 child->p_exitsig = SIGCHLD; 510 511 LIST_REMOVE(child, p_sibling); 512 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); 513 child->p_pptr = parent; 514 } 515 516 void 517 proc_zap(struct proc *p) 518 { 519 pool_put(&rusage_pool, p->p_ru); 520 521 /* 522 * Finally finished with old proc entry. 523 * Unlink it from its process group and free it. 524 */ 525 leavepgrp(p); 526 LIST_REMOVE(p, p_list); /* off zombproc */ 527 LIST_REMOVE(p, p_sibling); 528 529 /* 530 * Decrement the count of procs running with this uid. 531 */ 532 (void)chgproccnt(p->p_cred->p_ruid, -1); 533 534 /* 535 * Free up credentials. 536 */ 537 if (--p->p_cred->p_refcnt == 0) { 538 crfree(p->p_cred->pc_ucred); 539 pool_put(&pcred_pool, p->p_cred); 540 } 541 542 /* 543 * Release reference to text vnode 544 */ 545 if (p->p_textvp) 546 vrele(p->p_textvp); 547 548 pool_put(&proc_pool, p); 549 nprocs--; 550 } 551 552