1 /* $OpenBSD: kern_exit.c,v 1.37 2001/11/12 01:26:09 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. All advertising materials mentioning features or use of this software 22 * must display the following acknowledgement: 23 * This product includes software developed by the University of 24 * California, Berkeley and its contributors. 25 * 4. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 * 41 * @(#)kern_exit.c 8.7 (Berkeley) 2/12/94 42 */ 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/map.h> 47 #include <sys/ioctl.h> 48 #include <sys/proc.h> 49 #include <sys/tty.h> 50 #include <sys/time.h> 51 #include <sys/resource.h> 52 #include <sys/kernel.h> 53 #include <sys/proc.h> 54 #include <sys/buf.h> 55 #include <sys/wait.h> 56 #include <sys/file.h> 57 #include <sys/vnode.h> 58 #include <sys/syslog.h> 59 #include <sys/malloc.h> 60 #include <sys/resourcevar.h> 61 #include <sys/ptrace.h> 62 #include <sys/acct.h> 63 #include <sys/filedesc.h> 64 #include <sys/signalvar.h> 65 #include <sys/sched.h> 66 #include <sys/ktrace.h> 67 #include <sys/pool.h> 68 #ifdef SYSVSHM 69 #include <sys/shm.h> 70 #endif 71 #ifdef SYSVSEM 72 #include <sys/sem.h> 73 #endif 74 75 #include <sys/mount.h> 76 #include <sys/syscallargs.h> 77 78 #include <machine/cpu.h> 79 80 #include <uvm/uvm_extern.h> 81 82 void proc_zap __P((struct proc *)); 83 84 /* 85 * exit -- 86 * Death of process. 87 */ 88 int 89 sys_exit(p, v, retval) 90 struct proc *p; 91 void *v; 92 register_t *retval; 93 { 94 struct sys_exit_args /* { 95 syscallarg(int) rval; 96 } */ *uap = v; 97 98 exit1(p, W_EXITCODE(SCARG(uap, rval), 0)); 99 /* NOTREACHED */ 100 return (0); 101 } 102 103 /* 104 * Exit: deallocate address space and other resources, change proc state 105 * to zombie, and unlink proc from allproc and parent's lists. Save exit 106 * status and rusage for wait(). Check for child processes and orphan them. 107 */ 108 void 109 exit1(p, rv) 110 struct proc *p; 111 int rv; 112 { 113 struct proc *q, *nq; 114 struct vmspace *vm; 115 116 if (p->p_pid == 1) 117 panic("init died (signal %d, exit %d)", 118 WTERMSIG(rv), WEXITSTATUS(rv)); 119 120 if (p->p_flag & P_PROFIL) 121 stopprofclock(p); 122 MALLOC(p->p_ru, struct rusage *, sizeof(struct rusage), 123 M_ZOMBIE, M_WAITOK); 124 /* 125 * If parent is waiting for us to exit or exec, P_PPWAIT is set; we 126 * wake up the parent early to avoid deadlock. 127 */ 128 p->p_flag |= P_WEXIT; 129 p->p_flag &= ~P_TRACED; 130 if (p->p_flag & P_PPWAIT) { 131 p->p_flag &= ~P_PPWAIT; 132 wakeup((caddr_t)p->p_pptr); 133 } 134 p->p_sigignore = ~0; 135 p->p_siglist = 0; 136 timeout_del(&p->p_realit_to); 137 138 /* 139 * Close open files and release open-file table. 140 * This may block! 141 */ 142 fdfree(p); 143 144 /* The next three chunks should probably be moved to vmspace_exit. */ 145 vm = p->p_vmspace; 146 #ifdef SYSVSEM 147 semexit(p); 148 #endif 149 /* 150 * Release user portion of address space. 151 * This releases references to vnodes, 152 * which could cause I/O if the file has been unlinked. 153 * Need to do this early enough that we can still sleep. 154 * Can't free the entire vmspace as the kernel stack 155 * may be mapped within that space also. 156 */ 157 if (vm->vm_refcnt == 1) 158 (void) uvm_deallocate(&vm->vm_map, VM_MIN_ADDRESS, 159 VM_MAXUSER_ADDRESS - VM_MIN_ADDRESS); 160 161 if (SESS_LEADER(p)) { 162 register struct session *sp = p->p_session; 163 164 if (sp->s_ttyvp) { 165 /* 166 * Controlling process. 167 * Signal foreground pgrp, 168 * drain controlling terminal 169 * and revoke access to controlling terminal. 170 */ 171 if (sp->s_ttyp->t_session == sp) { 172 if (sp->s_ttyp->t_pgrp) 173 pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1); 174 (void) ttywait(sp->s_ttyp); 175 /* 176 * The tty could have been revoked 177 * if we blocked. 178 */ 179 if (sp->s_ttyvp) 180 VOP_REVOKE(sp->s_ttyvp, REVOKEALL); 181 } 182 if (sp->s_ttyvp) 183 vrele(sp->s_ttyvp); 184 sp->s_ttyvp = NULL; 185 /* 186 * s_ttyp is not zero'd; we use this to indicate 187 * that the session once had a controlling terminal. 188 * (for logging and informational purposes) 189 */ 190 } 191 sp->s_leader = NULL; 192 } 193 fixjobc(p, p->p_pgrp, 0); 194 (void)acct_process(p); 195 #ifdef KTRACE 196 /* 197 * release trace file 198 */ 199 p->p_traceflag = 0; /* don't trace the vrele() */ 200 if (p->p_tracep) 201 ktrsettracevnode(p, NULL); 202 #endif 203 /* 204 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 205 */ 206 p->p_stat = SDEAD; 207 208 /* 209 * Remove proc from pidhash chain so looking it up won't 210 * work. Move it from allproc to zombproc, but do not yet 211 * wake up the reaper. We will put the proc on the 212 * deadproc list later (using the p_hash member), and 213 * wake up the reaper when we do. 214 */ 215 LIST_REMOVE(p, p_hash); 216 LIST_REMOVE(p, p_list); 217 LIST_INSERT_HEAD(&zombproc, p, p_list); 218 219 /* 220 * Give orphaned children to init(8). 221 */ 222 q = p->p_children.lh_first; 223 if (q) /* only need this if any child is S_ZOMB */ 224 wakeup((caddr_t)initproc); 225 for (; q != 0; q = nq) { 226 nq = q->p_sibling.le_next; 227 proc_reparent(q, initproc); 228 /* 229 * Traced processes are killed 230 * since their existence means someone is screwing up. 231 */ 232 if (q->p_flag & P_TRACED) { 233 q->p_flag &= ~P_TRACED; 234 psignal(q, SIGKILL); 235 } 236 } 237 238 /* 239 * Save exit status and final rusage info, adding in child rusage 240 * info and self times. 241 */ 242 p->p_xstat = rv; 243 *p->p_ru = p->p_stats->p_ru; 244 calcru(p, &p->p_ru->ru_utime, &p->p_ru->ru_stime, NULL); 245 ruadd(p->p_ru, &p->p_stats->p_cru); 246 247 /* 248 * clear %cpu usage during swap 249 */ 250 p->p_pctcpu = 0; 251 252 /* 253 * notify interested parties of our demise. 254 */ 255 KNOTE(&p->p_klist, NOTE_EXIT); 256 257 /* 258 * Notify parent that we're gone. If we have P_NOZOMBIE or parent has 259 * the P_NOCLDWAIT flag set, notify process 1 instead (and hope it 260 * will handle this situation). 261 */ 262 if ((p->p_flag & P_NOZOMBIE) || (p->p_pptr->p_flag & P_NOCLDWAIT)) { 263 struct proc *pp = p->p_pptr; 264 proc_reparent(p, initproc); 265 /* 266 * If this was the last child of our parent, notify 267 * parent, so in case he was wait(2)ing, he will 268 * continue. 269 */ 270 if (pp->p_children.lh_first == NULL) 271 wakeup((caddr_t)pp); 272 } 273 274 if ((p->p_flag & P_FSTRACE) == 0 && p->p_exitsig != 0) 275 psignal(p->p_pptr, P_EXITSIG(p)); 276 wakeup((caddr_t)p->p_pptr); 277 278 /* 279 * Notify procfs debugger 280 */ 281 if (p->p_flag & P_FSTRACE) 282 wakeup((caddr_t)p); 283 284 /* 285 * Release the process's signal state. 286 */ 287 sigactsfree(p); 288 289 /* 290 * Clear curproc after we've done all operations 291 * that could block, and before tearing down the rest 292 * of the process state that might be used from clock, etc. 293 * Also, can't clear curproc while we're still runnable, 294 * as we're not on a run queue (we are current, just not 295 * a proper proc any longer!). 296 * 297 * Other substructures are freed from wait(). 298 */ 299 curproc = NULL; 300 limfree(p->p_limit); 301 p->p_limit = NULL; 302 303 /* 304 * Finally, call machine-dependent code to switch to a new 305 * context (possibly the idle context). Once we are no longer 306 * using the dead process's vmspace and stack, exit2() will be 307 * called to schedule those resources to be released by the 308 * reaper thread. 309 * 310 * Note that cpu_exit() will end with a call equivalent to 311 * cpu_switch(), finishing our execution (pun intended). 312 */ 313 cpu_exit(p); 314 } 315 316 /* 317 * We are called from cpu_exit() once it is safe to schedule the 318 * dead process's resources to be freed. 319 * 320 * NOTE: One must be careful with locking in this routine. It's 321 * called from a critical section in machine-dependent code, so 322 * we should refrain from changing any interrupt state. 323 * 324 * We lock the deadproc list (a spin lock), place the proc on that 325 * list (using the p_hash member), and wake up the reaper. 326 */ 327 void 328 exit2(p) 329 struct proc *p; 330 { 331 332 simple_lock(&deadproc_slock); 333 LIST_INSERT_HEAD(&deadproc, p, p_hash); 334 simple_unlock(&deadproc_slock); 335 336 wakeup(&deadproc); 337 } 338 339 /* 340 * Process reaper. This is run by a kernel thread to free the resources 341 * of a dead process. Once the resources are free, the process becomes 342 * a zombie, and the parent is allowed to read the undead's status. 343 */ 344 void 345 reaper() 346 { 347 struct proc *p; 348 349 for (;;) { 350 simple_lock(&deadproc_slock); 351 p = LIST_FIRST(&deadproc); 352 if (p == NULL) { 353 /* No work for us; go to sleep until someone exits. */ 354 simple_unlock(&deadproc_slock); 355 (void) tsleep(&deadproc, PVM, "reaper", 0); 356 continue; 357 } 358 359 /* Remove us from the deadproc list. */ 360 LIST_REMOVE(p, p_hash); 361 simple_unlock(&deadproc_slock); 362 363 /* 364 * Give machine-dependent code a chance to free any 365 * resources it couldn't free while still running on 366 * that process's context. This must be done before 367 * uvm_exit(), in case these resources are in the PCB. 368 */ 369 cpu_wait(p); 370 371 /* 372 * Free the VM resources we're still holding on to. 373 * We must do this from a valid thread because doing 374 * so may block. 375 */ 376 uvm_exit(p); 377 378 /* Process is now a true zombie. */ 379 if ((p->p_flag & P_NOZOMBIE) == 0) { 380 p->p_stat = SZOMB; 381 382 /* Wake up the parent so it can get exit status. */ 383 psignal(p->p_pptr, SIGCHLD); 384 wakeup((caddr_t)p->p_pptr); 385 } else { 386 /* Noone will wait for us. Just zap the process now */ 387 proc_zap(p); 388 } 389 } 390 } 391 392 int 393 sys_wait4(q, v, retval) 394 register struct proc *q; 395 void *v; 396 register_t *retval; 397 { 398 register struct sys_wait4_args /* { 399 syscallarg(int) pid; 400 syscallarg(int *) status; 401 syscallarg(int) options; 402 syscallarg(struct rusage *) rusage; 403 } */ *uap = v; 404 register int nfound; 405 register struct proc *p, *t; 406 int status, error; 407 408 if (SCARG(uap, pid) == 0) 409 SCARG(uap, pid) = -q->p_pgid; 410 if (SCARG(uap, options) &~ (WUNTRACED|WNOHANG|WALTSIG)) 411 return (EINVAL); 412 413 loop: 414 nfound = 0; 415 for (p = q->p_children.lh_first; p != 0; p = p->p_sibling.le_next) { 416 if ((p->p_flag & P_NOZOMBIE) || 417 (SCARG(uap, pid) != WAIT_ANY && 418 p->p_pid != SCARG(uap, pid) && 419 p->p_pgid != -SCARG(uap, pid))) 420 continue; 421 422 /* 423 * Wait for processes with p_exitsig != SIGCHLD processes only 424 * if WALTSIG is set; wait for processes with pexitsig == 425 * SIGCHLD only if WALTSIG is clear. 426 */ 427 if ((SCARG(uap, options) & WALTSIG) ? 428 (p->p_exitsig == SIGCHLD) : (P_EXITSIG(p) != SIGCHLD)) 429 continue; 430 431 nfound++; 432 if (p->p_stat == SZOMB) { 433 retval[0] = p->p_pid; 434 435 if (SCARG(uap, status)) { 436 status = p->p_xstat; /* convert to int */ 437 error = copyout((caddr_t)&status, 438 (caddr_t)SCARG(uap, status), 439 sizeof(status)); 440 if (error) 441 return (error); 442 } 443 if (SCARG(uap, rusage) && 444 (error = copyout((caddr_t)p->p_ru, 445 (caddr_t)SCARG(uap, rusage), 446 sizeof(struct rusage)))) 447 return (error); 448 449 /* 450 * If we got the child via a ptrace 'attach', 451 * we need to give it back to the old parent. 452 */ 453 if (p->p_oppid && (t = pfind(p->p_oppid))) { 454 p->p_oppid = 0; 455 proc_reparent(p, t); 456 if (p->p_exitsig != 0) 457 psignal(t, P_EXITSIG(p)); 458 wakeup((caddr_t)t); 459 return (0); 460 } 461 462 scheduler_wait_hook(q, p); 463 p->p_xstat = 0; 464 ruadd(&q->p_stats->p_cru, p->p_ru); 465 466 proc_zap(p); 467 468 return (0); 469 } 470 if (p->p_stat == SSTOP && (p->p_flag & P_WAITED) == 0 && 471 (p->p_flag & P_TRACED || SCARG(uap, options) & WUNTRACED)) { 472 p->p_flag |= P_WAITED; 473 retval[0] = p->p_pid; 474 475 if (SCARG(uap, status)) { 476 status = W_STOPCODE(p->p_xstat); 477 error = copyout((caddr_t)&status, 478 (caddr_t)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((caddr_t)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(p) 518 struct proc *p; 519 { 520 521 FREE(p->p_ru, M_ZOMBIE); 522 523 /* 524 * Finally finished with old proc entry. 525 * Unlink it from its process group and free it. 526 */ 527 leavepgrp(p); 528 LIST_REMOVE(p, p_list); /* off zombproc */ 529 LIST_REMOVE(p, p_sibling); 530 531 /* 532 * Decrement the count of procs running with this uid. 533 */ 534 (void)chgproccnt(p->p_cred->p_ruid, -1); 535 536 /* 537 * Free up credentials. 538 */ 539 if (--p->p_cred->p_refcnt == 0) { 540 crfree(p->p_cred->pc_ucred); 541 FREE(p->p_cred, M_SUBPROC); 542 } 543 544 /* 545 * Release reference to text vnode 546 */ 547 if (p->p_textvp) 548 vrele(p->p_textvp); 549 550 pool_put(&proc_pool, p); 551 nprocs--; 552 } 553 554