1 /* $OpenBSD: kern_exit.c,v 1.47 2003/08/03 19:25:49 millert 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/proc.h> 49 #include <sys/buf.h> 50 #include <sys/wait.h> 51 #include <sys/file.h> 52 #include <sys/vnode.h> 53 #include <sys/syslog.h> 54 #include <sys/malloc.h> 55 #include <sys/resourcevar.h> 56 #include <sys/ptrace.h> 57 #include <sys/acct.h> 58 #include <sys/filedesc.h> 59 #include <sys/signalvar.h> 60 #include <sys/sched.h> 61 #include <sys/ktrace.h> 62 #include <sys/pool.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 (void)acct_process(p); 175 #ifdef KTRACE 176 /* 177 * release trace file 178 */ 179 p->p_traceflag = 0; /* don't trace the vrele() */ 180 if (p->p_tracep) 181 ktrsettracevnode(p, NULL); 182 #endif 183 #if NSYSTRACE > 0 184 if (ISSET(p->p_flag, P_SYSTRACE)) 185 systrace_exit(p); 186 #endif 187 /* 188 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 189 */ 190 p->p_stat = SDEAD; 191 192 /* 193 * Remove proc from pidhash chain so looking it up won't 194 * work. Move it from allproc to zombproc, but do not yet 195 * wake up the reaper. We will put the proc on the 196 * deadproc list later (using the p_hash member), and 197 * wake up the reaper when we do. 198 */ 199 LIST_REMOVE(p, p_hash); 200 LIST_REMOVE(p, p_list); 201 LIST_INSERT_HEAD(&zombproc, p, p_list); 202 203 /* 204 * Give orphaned children to init(8). 205 */ 206 q = p->p_children.lh_first; 207 if (q) /* only need this if any child is S_ZOMB */ 208 wakeup(initproc); 209 for (; q != 0; q = nq) { 210 nq = q->p_sibling.le_next; 211 proc_reparent(q, initproc); 212 /* 213 * Traced processes are killed 214 * since their existence means someone is screwing up. 215 */ 216 if (q->p_flag & P_TRACED) { 217 q->p_flag &= ~P_TRACED; 218 psignal(q, SIGKILL); 219 } 220 } 221 222 /* 223 * Save exit status and final rusage info, adding in child rusage 224 * info and self times. 225 */ 226 p->p_xstat = rv; 227 *p->p_ru = p->p_stats->p_ru; 228 calcru(p, &p->p_ru->ru_utime, &p->p_ru->ru_stime, NULL); 229 ruadd(p->p_ru, &p->p_stats->p_cru); 230 231 /* 232 * clear %cpu usage during swap 233 */ 234 p->p_pctcpu = 0; 235 236 /* 237 * notify interested parties of our demise. 238 */ 239 KNOTE(&p->p_klist, NOTE_EXIT); 240 241 /* 242 * Notify parent that we're gone. If we have P_NOZOMBIE or parent has 243 * the P_NOCLDWAIT flag set, notify process 1 instead (and hope it 244 * will handle this situation). 245 */ 246 if ((p->p_flag & P_NOZOMBIE) || (p->p_pptr->p_flag & P_NOCLDWAIT)) { 247 struct proc *pp = p->p_pptr; 248 proc_reparent(p, initproc); 249 /* 250 * If this was the last child of our parent, notify 251 * parent, so in case he was wait(2)ing, he will 252 * continue. 253 */ 254 if (pp->p_children.lh_first == NULL) 255 wakeup(pp); 256 } 257 258 if ((p->p_flag & P_FSTRACE) == 0 && p->p_exitsig != 0) 259 psignal(p->p_pptr, P_EXITSIG(p)); 260 wakeup(p->p_pptr); 261 262 /* 263 * Notify procfs debugger 264 */ 265 if (p->p_flag & P_FSTRACE) 266 wakeup(p); 267 268 /* 269 * Release the process's signal state. 270 */ 271 sigactsfree(p); 272 273 /* 274 * Clear curproc after we've done all operations 275 * that could block, and before tearing down the rest 276 * of the process state that might be used from clock, etc. 277 * Also, can't clear curproc while we're still runnable, 278 * as we're not on a run queue (we are current, just not 279 * a proper proc any longer!). 280 * 281 * Other substructures are freed from wait(). 282 */ 283 curproc = NULL; 284 limfree(p->p_limit); 285 p->p_limit = NULL; 286 287 /* 288 * If emulation has process exit hook, call it now. 289 */ 290 if (p->p_emul->e_proc_exit) 291 (*p->p_emul->e_proc_exit)(p); 292 293 /* 294 * Finally, call machine-dependent code to switch to a new 295 * context (possibly the idle context). Once we are no longer 296 * using the dead process's vmspace and stack, exit2() will be 297 * called to schedule those resources to be released by the 298 * reaper thread. 299 * 300 * Note that cpu_exit() will end with a call equivalent to 301 * cpu_switch(), finishing our execution (pun intended). 302 */ 303 cpu_exit(p); 304 } 305 306 /* 307 * We are called from cpu_exit() once it is safe to schedule the 308 * dead process's resources to be freed. 309 * 310 * NOTE: One must be careful with locking in this routine. It's 311 * called from a critical section in machine-dependent code, so 312 * we should refrain from changing any interrupt state. 313 * 314 * We lock the deadproc list (a spin lock), place the proc on that 315 * list (using the p_hash member), and wake up the reaper. 316 */ 317 void 318 exit2(p) 319 struct proc *p; 320 { 321 322 simple_lock(&deadproc_slock); 323 LIST_INSERT_HEAD(&deadproc, p, p_hash); 324 simple_unlock(&deadproc_slock); 325 326 wakeup(&deadproc); 327 } 328 329 /* 330 * Process reaper. This is run by a kernel thread to free the resources 331 * of a dead process. Once the resources are free, the process becomes 332 * a zombie, and the parent is allowed to read the undead's status. 333 */ 334 void 335 reaper(void) 336 { 337 struct proc *p; 338 339 for (;;) { 340 simple_lock(&deadproc_slock); 341 p = LIST_FIRST(&deadproc); 342 if (p == NULL) { 343 /* No work for us; go to sleep until someone exits. */ 344 simple_unlock(&deadproc_slock); 345 (void) tsleep(&deadproc, PVM, "reaper", 0); 346 continue; 347 } 348 349 /* Remove us from the deadproc list. */ 350 LIST_REMOVE(p, p_hash); 351 simple_unlock(&deadproc_slock); 352 353 /* 354 * Give machine-dependent code a chance to free any 355 * resources it couldn't free while still running on 356 * that process's context. This must be done before 357 * uvm_exit(), in case these resources are in the PCB. 358 */ 359 cpu_wait(p); 360 361 /* 362 * Free the VM resources we're still holding on to. 363 * We must do this from a valid thread because doing 364 * so may block. 365 */ 366 uvm_exit(p); 367 368 /* Process is now a true zombie. */ 369 if ((p->p_flag & P_NOZOMBIE) == 0) { 370 p->p_stat = SZOMB; 371 372 /* Wake up the parent so it can get exit status. */ 373 psignal(p->p_pptr, SIGCHLD); 374 wakeup(p->p_pptr); 375 } else { 376 /* Noone will wait for us. Just zap the process now */ 377 proc_zap(p); 378 } 379 } 380 } 381 382 int 383 sys_wait4(q, v, retval) 384 register struct proc *q; 385 void *v; 386 register_t *retval; 387 { 388 register struct sys_wait4_args /* { 389 syscallarg(int) pid; 390 syscallarg(int *) status; 391 syscallarg(int) options; 392 syscallarg(struct rusage *) rusage; 393 } */ *uap = v; 394 register int nfound; 395 register struct proc *p, *t; 396 int status, error; 397 398 if (SCARG(uap, pid) == 0) 399 SCARG(uap, pid) = -q->p_pgid; 400 if (SCARG(uap, options) &~ (WUNTRACED|WNOHANG|WALTSIG|WCONTINUED)) 401 return (EINVAL); 402 403 loop: 404 nfound = 0; 405 for (p = q->p_children.lh_first; p != 0; p = p->p_sibling.le_next) { 406 if ((p->p_flag & P_NOZOMBIE) || 407 (SCARG(uap, pid) != WAIT_ANY && 408 p->p_pid != SCARG(uap, pid) && 409 p->p_pgid != -SCARG(uap, pid))) 410 continue; 411 412 /* 413 * Wait for processes with p_exitsig != SIGCHLD processes only 414 * if WALTSIG is set; wait for processes with pexitsig == 415 * SIGCHLD only if WALTSIG is clear. 416 */ 417 if ((SCARG(uap, options) & WALTSIG) ? 418 (p->p_exitsig == SIGCHLD) : (P_EXITSIG(p) != SIGCHLD)) 419 continue; 420 421 nfound++; 422 if (p->p_stat == SZOMB) { 423 retval[0] = p->p_pid; 424 425 if (SCARG(uap, status)) { 426 status = p->p_xstat; /* convert to int */ 427 error = copyout(&status, 428 SCARG(uap, status), sizeof(status)); 429 if (error) 430 return (error); 431 } 432 if (SCARG(uap, rusage) && 433 (error = copyout(p->p_ru, 434 SCARG(uap, rusage), sizeof(struct rusage)))) 435 return (error); 436 437 /* 438 * If we got the child via a ptrace 'attach', 439 * we need to give it back to the old parent. 440 */ 441 if (p->p_oppid && (t = pfind(p->p_oppid))) { 442 p->p_oppid = 0; 443 proc_reparent(p, t); 444 if (p->p_exitsig != 0) 445 psignal(t, P_EXITSIG(p)); 446 wakeup(t); 447 return (0); 448 } 449 450 scheduler_wait_hook(q, p); 451 p->p_xstat = 0; 452 ruadd(&q->p_stats->p_cru, p->p_ru); 453 454 proc_zap(p); 455 456 return (0); 457 } 458 if (p->p_stat == SSTOP && (p->p_flag & P_WAITED) == 0 && 459 (p->p_flag & P_TRACED || SCARG(uap, options) & WUNTRACED)) { 460 p->p_flag |= P_WAITED; 461 retval[0] = p->p_pid; 462 463 if (SCARG(uap, status)) { 464 status = W_STOPCODE(p->p_xstat); 465 error = copyout(&status, SCARG(uap, status), 466 sizeof(status)); 467 } else 468 error = 0; 469 return (error); 470 } 471 if ((SCARG(uap, options) & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 472 p->p_flag &= ~P_CONTINUED; 473 retval[0] = p->p_pid; 474 475 if (SCARG(uap, status)) { 476 status = _WCONTINUED; 477 error = copyout(&status, SCARG(uap, status), 478 sizeof(status)); 479 } else 480 error = 0; 481 return (error); 482 } 483 } 484 if (nfound == 0) 485 return (ECHILD); 486 if (SCARG(uap, options) & WNOHANG) { 487 retval[0] = 0; 488 return (0); 489 } 490 if ((error = tsleep(q, PWAIT | PCATCH, "wait", 0)) != 0) 491 return (error); 492 goto loop; 493 } 494 495 /* 496 * make process 'parent' the new parent of process 'child'. 497 */ 498 void 499 proc_reparent(child, parent) 500 register struct proc *child; 501 register struct proc *parent; 502 { 503 504 if (child->p_pptr == parent) 505 return; 506 507 if (parent == initproc) 508 child->p_exitsig = SIGCHLD; 509 510 LIST_REMOVE(child, p_sibling); 511 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); 512 child->p_pptr = parent; 513 } 514 515 void 516 proc_zap(struct proc *p) 517 { 518 pool_put(&rusage_pool, p->p_ru); 519 520 /* 521 * Finally finished with old proc entry. 522 * Unlink it from its process group and free it. 523 */ 524 leavepgrp(p); 525 LIST_REMOVE(p, p_list); /* off zombproc */ 526 LIST_REMOVE(p, p_sibling); 527 528 /* 529 * Decrement the count of procs running with this uid. 530 */ 531 (void)chgproccnt(p->p_cred->p_ruid, -1); 532 533 /* 534 * Free up credentials. 535 */ 536 if (--p->p_cred->p_refcnt == 0) { 537 crfree(p->p_cred->pc_ucred); 538 pool_put(&pcred_pool, p->p_cred); 539 } 540 541 /* 542 * Release reference to text vnode 543 */ 544 if (p->p_textvp) 545 vrele(p->p_textvp); 546 547 pool_put(&proc_pool, p); 548 nprocs--; 549 } 550 551