1 /* $OpenBSD: kern_exit.c,v 1.33 2001/06/27 04:49:41 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 <vm/vm.h> 81 #include <vm/vm_kern.h> 82 83 #include <uvm/uvm_extern.h> 84 85 void proc_zap __P((struct proc *)); 86 87 /* 88 * exit -- 89 * Death of process. 90 */ 91 int 92 sys_exit(p, v, retval) 93 struct proc *p; 94 void *v; 95 register_t *retval; 96 { 97 struct sys_exit_args /* { 98 syscallarg(int) rval; 99 } */ *uap = v; 100 101 exit1(p, W_EXITCODE(SCARG(uap, rval), 0)); 102 /* NOTREACHED */ 103 return (0); 104 } 105 106 /* 107 * Exit: deallocate address space and other resources, change proc state 108 * to zombie, and unlink proc from allproc and parent's lists. Save exit 109 * status and rusage for wait(). Check for child processes and orphan them. 110 */ 111 void 112 exit1(p, rv) 113 register struct proc *p; 114 int rv; 115 { 116 register struct proc *q, *nq; 117 register struct vmspace *vm; 118 119 if (p->p_pid == 1) 120 panic("init died (signal %d, exit %d)", 121 WTERMSIG(rv), WEXITSTATUS(rv)); 122 123 if (p->p_flag & P_PROFIL) 124 stopprofclock(p); 125 MALLOC(p->p_ru, struct rusage *, sizeof(struct rusage), 126 M_ZOMBIE, M_WAITOK); 127 /* 128 * If parent is waiting for us to exit or exec, P_PPWAIT is set; we 129 * wake up the parent early to avoid deadlock. 130 */ 131 p->p_flag |= P_WEXIT; 132 p->p_flag &= ~P_TRACED; 133 if (p->p_flag & P_PPWAIT) { 134 p->p_flag &= ~P_PPWAIT; 135 wakeup((caddr_t)p->p_pptr); 136 } 137 p->p_sigignore = ~0; 138 p->p_siglist = 0; 139 timeout_del(&p->p_realit_to); 140 141 /* 142 * Close open files and release open-file table. 143 * This may block! 144 */ 145 fdfree(p); 146 147 /* The next three chunks should probably be moved to vmspace_exit. */ 148 vm = p->p_vmspace; 149 #ifdef SYSVSHM 150 if (vm->vm_shm && vm->vm_refcnt == 1) 151 shmexit(vm); 152 #endif 153 #ifdef SYSVSEM 154 semexit(p); 155 #endif 156 /* 157 * Release user portion of address space. 158 * This releases references to vnodes, 159 * which could cause I/O if the file has been unlinked. 160 * Need to do this early enough that we can still sleep. 161 * Can't free the entire vmspace as the kernel stack 162 * may be mapped within that space also. 163 */ 164 if (vm->vm_refcnt == 1) 165 (void) uvm_deallocate(&vm->vm_map, VM_MIN_ADDRESS, 166 VM_MAXUSER_ADDRESS - VM_MIN_ADDRESS); 167 168 if (SESS_LEADER(p)) { 169 register struct session *sp = p->p_session; 170 171 if (sp->s_ttyvp) { 172 /* 173 * Controlling process. 174 * Signal foreground pgrp, 175 * drain controlling terminal 176 * and revoke access to controlling terminal. 177 */ 178 if (sp->s_ttyp->t_session == sp) { 179 if (sp->s_ttyp->t_pgrp) 180 pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1); 181 (void) ttywait(sp->s_ttyp); 182 /* 183 * The tty could have been revoked 184 * if we blocked. 185 */ 186 if (sp->s_ttyvp) 187 VOP_REVOKE(sp->s_ttyvp, REVOKEALL); 188 } 189 if (sp->s_ttyvp) 190 vrele(sp->s_ttyvp); 191 sp->s_ttyvp = NULL; 192 /* 193 * s_ttyp is not zero'd; we use this to indicate 194 * that the session once had a controlling terminal. 195 * (for logging and informational purposes) 196 */ 197 } 198 sp->s_leader = NULL; 199 } 200 fixjobc(p, p->p_pgrp, 0); 201 (void)acct_process(p); 202 #ifdef KTRACE 203 /* 204 * release trace file 205 */ 206 p->p_traceflag = 0; /* don't trace the vrele() */ 207 if (p->p_tracep) 208 ktrsettracevnode(p, NULL); 209 #endif 210 /* 211 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 212 */ 213 p->p_stat = SDEAD; 214 215 /* 216 * Remove proc from pidhash chain so looking it up won't 217 * work. Move it from allproc to zombproc, but do not yet 218 * wake up the reaper. We will put the proc on the 219 * deadproc list later (using the p_hash member), and 220 * wake up the reaper when we do. 221 */ 222 LIST_REMOVE(p, p_hash); 223 LIST_REMOVE(p, p_list); 224 LIST_INSERT_HEAD(&zombproc, p, p_list); 225 226 /* 227 * Give orphaned children to init(8). 228 */ 229 q = p->p_children.lh_first; 230 if (q) /* only need this if any child is S_ZOMB */ 231 wakeup((caddr_t)initproc); 232 for (; q != 0; q = nq) { 233 nq = q->p_sibling.le_next; 234 proc_reparent(q, initproc); 235 /* 236 * Traced processes are killed 237 * since their existence means someone is screwing up. 238 */ 239 if (q->p_flag & P_TRACED) { 240 q->p_flag &= ~P_TRACED; 241 psignal(q, SIGKILL); 242 } 243 } 244 245 /* 246 * Save exit status and final rusage info, adding in child rusage 247 * info and self times. 248 */ 249 p->p_xstat = rv; 250 *p->p_ru = p->p_stats->p_ru; 251 calcru(p, &p->p_ru->ru_utime, &p->p_ru->ru_stime, NULL); 252 ruadd(p->p_ru, &p->p_stats->p_cru); 253 254 /* 255 * clear %cpu usage during swap 256 */ 257 p->p_pctcpu = 0; 258 259 /* 260 * notify interested parties of our demise. 261 */ 262 KNOTE(&p->p_klist, NOTE_EXIT); 263 264 /* 265 * Notify parent that we're gone. If we have P_NOZOMBIE or parent has 266 * the P_NOCLDWAIT flag set, notify process 1 instead (and hope it 267 * will handle this situation). 268 */ 269 if ((p->p_flag & P_NOZOMBIE) || (p->p_pptr->p_flag & P_NOCLDWAIT)) { 270 struct proc *pp = p->p_pptr; 271 proc_reparent(p, initproc); 272 /* 273 * If this was the last child of our parent, notify 274 * parent, so in case he was wait(2)ing, he will 275 * continue. 276 */ 277 if (pp->p_children.lh_first == NULL) 278 wakeup((caddr_t)pp); 279 } 280 281 if ((p->p_flag & P_FSTRACE) == 0 && p->p_exitsig != 0) 282 psignal(p->p_pptr, P_EXITSIG(p)); 283 wakeup((caddr_t)p->p_pptr); 284 285 /* 286 * Notify procfs debugger 287 */ 288 if (p->p_flag & P_FSTRACE) 289 wakeup((caddr_t)p); 290 291 /* 292 * Release the process's signal state. 293 */ 294 sigactsfree(p); 295 296 /* 297 * Clear curproc after we've done all operations 298 * that could block, and before tearing down the rest 299 * of the process state that might be used from clock, etc. 300 * Also, can't clear curproc while we're still runnable, 301 * as we're not on a run queue (we are current, just not 302 * a proper proc any longer!). 303 * 304 * Other substructures are freed from wait(). 305 */ 306 curproc = NULL; 307 limfree(p->p_limit); 308 p->p_limit = NULL; 309 310 /* 311 * Finally, call machine-dependent code to switch to a new 312 * context (possibly the idle context). Once we are no longer 313 * using the dead process's vmspace and stack, exit2() will be 314 * called to schedule those resources to be released by the 315 * reaper thread. 316 * 317 * Note that cpu_exit() will end with a call equivalent to 318 * cpu_switch(), finishing our execution (pun intended). 319 */ 320 cpu_exit(p); 321 } 322 323 /* 324 * We are called from cpu_exit() once it is safe to schedule the 325 * dead process's resources to be freed. 326 * 327 * NOTE: One must be careful with locking in this routine. It's 328 * called from a critical section in machine-dependent code, so 329 * we should refrain from changing any interrupt state. 330 * 331 * We lock the deadproc list (a spin lock), place the proc on that 332 * list (using the p_hash member), and wake up the reaper. 333 */ 334 void 335 exit2(p) 336 struct proc *p; 337 { 338 339 simple_lock(&deadproc_slock); 340 LIST_INSERT_HEAD(&deadproc, p, p_hash); 341 simple_unlock(&deadproc_slock); 342 343 wakeup(&deadproc); 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() 353 { 354 struct proc *p; 355 356 for (;;) { 357 simple_lock(&deadproc_slock); 358 p = LIST_FIRST(&deadproc); 359 if (p == NULL) { 360 /* No work for us; go to sleep until someone exits. */ 361 simple_unlock(&deadproc_slock); 362 (void) tsleep(&deadproc, PVM, "reaper", 0); 363 continue; 364 } 365 366 /* Remove us from the deadproc list. */ 367 LIST_REMOVE(p, p_hash); 368 simple_unlock(&deadproc_slock); 369 370 /* 371 * Give machine-dependent code a chance to free any 372 * resources it couldn't free while still running on 373 * that process's context. This must be done before 374 * uvm_exit(), in case these resources are in the PCB. 375 */ 376 cpu_wait(p); 377 378 /* 379 * Free the VM resources we're still holding on to. 380 * We must do this from a valid thread because doing 381 * so may block. 382 */ 383 uvm_exit(p); 384 385 /* Process is now a true zombie. */ 386 if ((p->p_flag & P_NOZOMBIE) == 0) { 387 p->p_stat = SZOMB; 388 389 /* Wake up the parent so it can get exit status. */ 390 psignal(p->p_pptr, SIGCHLD); 391 wakeup((caddr_t)p->p_pptr); 392 } else { 393 /* Noone will wait for us. Just zap the process now */ 394 proc_zap(p); 395 } 396 } 397 } 398 399 int 400 sys_wait4(q, v, retval) 401 register struct proc *q; 402 void *v; 403 register_t *retval; 404 { 405 register struct sys_wait4_args /* { 406 syscallarg(int) pid; 407 syscallarg(int *) status; 408 syscallarg(int) options; 409 syscallarg(struct rusage *) rusage; 410 } */ *uap = v; 411 register int nfound; 412 register struct proc *p, *t; 413 int status, error; 414 415 if (SCARG(uap, pid) == 0) 416 SCARG(uap, pid) = -q->p_pgid; 417 if (SCARG(uap, options) &~ (WUNTRACED|WNOHANG|WALTSIG)) 418 return (EINVAL); 419 420 loop: 421 nfound = 0; 422 for (p = q->p_children.lh_first; p != 0; p = p->p_sibling.le_next) { 423 if ((p->p_flag & P_NOZOMBIE) || 424 (SCARG(uap, pid) != WAIT_ANY && 425 p->p_pid != SCARG(uap, pid) && 426 p->p_pgid != -SCARG(uap, pid))) 427 continue; 428 429 /* 430 * Wait for processes with p_exitsig != SIGCHLD processes only 431 * if WALTSIG is set; wait for processes with pexitsig == 432 * SIGCHLD only if WALTSIG is clear. 433 */ 434 if ((SCARG(uap, options) & WALTSIG) ? 435 (p->p_exitsig == SIGCHLD) : (P_EXITSIG(p) != SIGCHLD)) 436 continue; 437 438 nfound++; 439 if (p->p_stat == SZOMB) { 440 retval[0] = p->p_pid; 441 442 if (SCARG(uap, status)) { 443 status = p->p_xstat; /* convert to int */ 444 error = copyout((caddr_t)&status, 445 (caddr_t)SCARG(uap, status), 446 sizeof(status)); 447 if (error) 448 return (error); 449 } 450 if (SCARG(uap, rusage) && 451 (error = copyout((caddr_t)p->p_ru, 452 (caddr_t)SCARG(uap, rusage), 453 sizeof(struct rusage)))) 454 return (error); 455 456 /* 457 * If we got the child via a ptrace 'attach', 458 * we need to give it back to the old parent. 459 */ 460 if (p->p_oppid && (t = pfind(p->p_oppid))) { 461 p->p_oppid = 0; 462 proc_reparent(p, t); 463 if (p->p_exitsig != 0) 464 psignal(t, P_EXITSIG(p)); 465 wakeup((caddr_t)t); 466 return (0); 467 } 468 469 scheduler_wait_hook(q, p); 470 p->p_xstat = 0; 471 ruadd(&q->p_stats->p_cru, p->p_ru); 472 473 proc_zap(p); 474 475 return (0); 476 } 477 if (p->p_stat == SSTOP && (p->p_flag & P_WAITED) == 0 && 478 (p->p_flag & P_TRACED || SCARG(uap, options) & WUNTRACED)) { 479 p->p_flag |= P_WAITED; 480 retval[0] = p->p_pid; 481 482 if (SCARG(uap, status)) { 483 status = W_STOPCODE(p->p_xstat); 484 error = copyout((caddr_t)&status, 485 (caddr_t)SCARG(uap, status), 486 sizeof(status)); 487 } else 488 error = 0; 489 return (error); 490 } 491 } 492 if (nfound == 0) 493 return (ECHILD); 494 if (SCARG(uap, options) & WNOHANG) { 495 retval[0] = 0; 496 return (0); 497 } 498 if ((error = tsleep((caddr_t)q, PWAIT | PCATCH, "wait", 0)) != 0) 499 return (error); 500 goto loop; 501 } 502 503 /* 504 * make process 'parent' the new parent of process 'child'. 505 */ 506 void 507 proc_reparent(child, parent) 508 register struct proc *child; 509 register struct proc *parent; 510 { 511 512 if (child->p_pptr == parent) 513 return; 514 515 if (parent == initproc) 516 child->p_exitsig = SIGCHLD; 517 518 LIST_REMOVE(child, p_sibling); 519 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); 520 child->p_pptr = parent; 521 } 522 523 void 524 proc_zap(p) 525 struct proc *p; 526 { 527 528 FREE(p->p_ru, M_ZOMBIE); 529 530 /* 531 * Finally finished with old proc entry. 532 * Unlink it from its process group and free it. 533 */ 534 leavepgrp(p); 535 LIST_REMOVE(p, p_list); /* off zombproc */ 536 LIST_REMOVE(p, p_sibling); 537 538 /* 539 * Decrement the count of procs running with this uid. 540 */ 541 (void)chgproccnt(p->p_cred->p_ruid, -1); 542 543 /* 544 * Free up credentials. 545 */ 546 if (--p->p_cred->p_refcnt == 0) { 547 crfree(p->p_cred->pc_ucred); 548 FREE(p->p_cred, M_SUBPROC); 549 } 550 551 /* 552 * Release reference to text vnode 553 */ 554 if (p->p_textvp) 555 vrele(p->p_textvp); 556 557 pool_put(&proc_pool, p); 558 nprocs--; 559 } 560 561