1 /* $OpenBSD: kern_exit.c,v 1.165 2018/07/13 09:25:23 beck 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/sysctl.h> 49 #include <sys/wait.h> 50 #include <sys/vnode.h> 51 #include <sys/syslog.h> 52 #include <sys/malloc.h> 53 #include <sys/resourcevar.h> 54 #include <sys/ptrace.h> 55 #include <sys/acct.h> 56 #include <sys/filedesc.h> 57 #include <sys/signalvar.h> 58 #include <sys/sched.h> 59 #include <sys/ktrace.h> 60 #include <sys/pool.h> 61 #include <sys/mutex.h> 62 #include <sys/pledge.h> 63 #ifdef SYSVSEM 64 #include <sys/sem.h> 65 #endif 66 #include <sys/witness.h> 67 68 #include <sys/mount.h> 69 #include <sys/syscallargs.h> 70 71 #include <uvm/uvm_extern.h> 72 73 void proc_finish_wait(struct proc *, struct proc *); 74 void process_zap(struct process *); 75 void proc_free(struct proc *); 76 void unveil_destroy(struct process *ps); 77 78 /* 79 * exit -- 80 * Death of process. 81 */ 82 int 83 sys_exit(struct proc *p, void *v, register_t *retval) 84 { 85 struct sys_exit_args /* { 86 syscallarg(int) rval; 87 } */ *uap = v; 88 89 exit1(p, W_EXITCODE(SCARG(uap, rval), 0), EXIT_NORMAL); 90 /* NOTREACHED */ 91 return (0); 92 } 93 94 int 95 sys___threxit(struct proc *p, void *v, register_t *retval) 96 { 97 struct sys___threxit_args /* { 98 syscallarg(pid_t *) notdead; 99 } */ *uap = v; 100 101 if (SCARG(uap, notdead) != NULL) { 102 pid_t zero = 0; 103 if (copyout(&zero, SCARG(uap, notdead), sizeof(zero))) 104 psignal(p, SIGSEGV); 105 } 106 exit1(p, 0, EXIT_THREAD); 107 108 return (0); 109 } 110 111 /* 112 * Exit: deallocate address space and other resources, change proc state 113 * to zombie, and unlink proc from allproc and parent's lists. Save exit 114 * status and rusage for wait(). Check for child processes and orphan them. 115 */ 116 void 117 exit1(struct proc *p, int rv, int flags) 118 { 119 struct process *pr, *qr, *nqr; 120 struct rusage *rup; 121 122 atomic_setbits_int(&p->p_flag, P_WEXIT); 123 124 pr = p->p_p; 125 126 /* single-threaded? */ 127 if (!P_HASSIBLING(p)) { 128 flags = EXIT_NORMAL; 129 } else { 130 /* nope, multi-threaded */ 131 if (flags == EXIT_NORMAL) 132 single_thread_set(p, SINGLE_EXIT, 0); 133 else if (flags == EXIT_THREAD) 134 single_thread_check(p, 0); 135 } 136 137 if (flags == EXIT_NORMAL) { 138 if (pr->ps_pid == 1) 139 panic("init died (signal %d, exit %d)", 140 WTERMSIG(rv), WEXITSTATUS(rv)); 141 142 atomic_setbits_int(&pr->ps_flags, PS_EXITING); 143 pr->ps_mainproc->p_xstat = rv; 144 145 /* 146 * If parent is waiting for us to exit or exec, PS_PPWAIT 147 * is set; we wake up the parent early to avoid deadlock. 148 */ 149 if (pr->ps_flags & PS_PPWAIT) { 150 atomic_clearbits_int(&pr->ps_flags, PS_PPWAIT); 151 atomic_clearbits_int(&pr->ps_pptr->ps_flags, 152 PS_ISPWAIT); 153 wakeup(pr->ps_pptr); 154 } 155 } 156 157 /* unlink ourselves from the active threads */ 158 TAILQ_REMOVE(&pr->ps_threads, p, p_thr_link); 159 if ((p->p_flag & P_THREAD) == 0) { 160 /* main thread gotta wait because it has the pid, et al */ 161 while (pr->ps_refcnt > 1) 162 tsleep(&pr->ps_threads, PUSER, "thrdeath", 0); 163 if (pr->ps_flags & PS_PROFIL) 164 stopprofclock(pr); 165 } 166 167 rup = pr->ps_ru; 168 if (rup == NULL) { 169 rup = pool_get(&rusage_pool, PR_WAITOK | PR_ZERO); 170 if (pr->ps_ru == NULL) { 171 pr->ps_ru = rup; 172 } else { 173 pool_put(&rusage_pool, rup); 174 rup = pr->ps_ru; 175 } 176 } 177 p->p_siglist = 0; 178 179 if ((p->p_flag & P_THREAD) == 0) { 180 /* close open files and release open-file table */ 181 fdfree(p); 182 183 timeout_del(&pr->ps_realit_to); 184 #ifdef SYSVSEM 185 semexit(pr); 186 #endif 187 killjobc(pr); 188 #ifdef ACCOUNTING 189 acct_process(p); 190 #endif 191 192 #ifdef KTRACE 193 /* release trace file */ 194 if (pr->ps_tracevp) 195 ktrcleartrace(pr); 196 #endif 197 198 /* 199 * If parent has the SAS_NOCLDWAIT flag set, we're not 200 * going to become a zombie. 201 */ 202 if (pr->ps_pptr->ps_sigacts->ps_flags & SAS_NOCLDWAIT) 203 atomic_setbits_int(&pr->ps_flags, PS_NOZOMBIE); 204 } 205 206 p->p_fd = NULL; /* zap the thread's copy */ 207 208 /* 209 * Remove proc from pidhash chain and allproc so looking 210 * it up won't work. We will put the proc on the 211 * deadproc list later (using the p_hash member), and 212 * wake up the reaper when we do. If this is the last 213 * thread of a process that isn't PS_NOZOMBIE, we'll put 214 * the process on the zombprocess list below. 215 */ 216 /* 217 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 218 */ 219 p->p_stat = SDEAD; 220 221 LIST_REMOVE(p, p_hash); 222 LIST_REMOVE(p, p_list); 223 224 if ((p->p_flag & P_THREAD) == 0) { 225 LIST_REMOVE(pr, ps_hash); 226 LIST_REMOVE(pr, ps_list); 227 228 if ((pr->ps_flags & PS_NOZOMBIE) == 0) 229 LIST_INSERT_HEAD(&zombprocess, pr, ps_list); 230 else { 231 /* 232 * Not going to be a zombie, so it's now off all 233 * the lists scanned by ispidtaken(), so block 234 * fast reuse of the pid now. 235 */ 236 freepid(pr->ps_pid); 237 } 238 239 /* 240 * Give orphaned children to init(8). 241 */ 242 qr = LIST_FIRST(&pr->ps_children); 243 if (qr) /* only need this if any child is S_ZOMB */ 244 wakeup(initprocess); 245 for (; qr != 0; qr = nqr) { 246 nqr = LIST_NEXT(qr, ps_sibling); 247 proc_reparent(qr, initprocess); 248 /* 249 * Traced processes are killed since their 250 * existence means someone is screwing up. 251 */ 252 if (qr->ps_flags & PS_TRACED && 253 !(qr->ps_flags & PS_EXITING)) { 254 atomic_clearbits_int(&qr->ps_flags, PS_TRACED); 255 /* 256 * If single threading is active, 257 * direct the signal to the active 258 * thread to avoid deadlock. 259 */ 260 if (qr->ps_single) 261 ptsignal(qr->ps_single, SIGKILL, 262 STHREAD); 263 else 264 prsignal(qr, SIGKILL); 265 } 266 } 267 } 268 269 /* add thread's accumulated rusage into the process's total */ 270 ruadd(rup, &p->p_ru); 271 tuagg(pr, p); 272 273 /* 274 * clear %cpu usage during swap 275 */ 276 p->p_pctcpu = 0; 277 278 if ((p->p_flag & P_THREAD) == 0) { 279 /* 280 * Final thread has died, so add on our children's rusage 281 * and calculate the total times 282 */ 283 calcru(&pr->ps_tu, &rup->ru_utime, &rup->ru_stime, NULL); 284 ruadd(rup, &pr->ps_cru); 285 286 /* notify interested parties of our demise and clean up */ 287 knote_processexit(p); 288 289 /* 290 * Notify parent that we're gone. If we're not going to 291 * become a zombie, reparent to process 1 (init) so that 292 * we can wake our original parent to possibly unblock 293 * wait4() to return ECHILD. 294 */ 295 if (pr->ps_flags & PS_NOZOMBIE) { 296 struct process *ppr = pr->ps_pptr; 297 proc_reparent(pr, initprocess); 298 wakeup(ppr); 299 } 300 301 /* 302 * Release the process's signal state. 303 */ 304 sigactsfree(pr); 305 } 306 307 /* just a thread? detach it from its process */ 308 if (p->p_flag & P_THREAD) { 309 /* scheduler_wait_hook(pr->ps_mainproc, p); XXX */ 310 if (--pr->ps_refcnt == 1) 311 wakeup(&pr->ps_threads); 312 KASSERT(pr->ps_refcnt > 0); 313 } 314 315 /* 316 * Other substructures are freed from reaper and wait(). 317 */ 318 319 /* 320 * Finally, call machine-dependent code to switch to a new 321 * context (possibly the idle context). Once we are no longer 322 * using the dead process's vmspace and stack, exit2() will be 323 * called to schedule those resources to be released by the 324 * reaper thread. 325 * 326 * Note that cpu_exit() will end with a call equivalent to 327 * cpu_switch(), finishing our execution (pun intended). 328 */ 329 uvmexp.swtch++; 330 cpu_exit(p); 331 panic("cpu_exit returned"); 332 } 333 334 /* 335 * Locking of this proclist is special; it's accessed in a 336 * critical section of process exit, and thus locking it can't 337 * modify interrupt state. We use a simple spin lock for this 338 * proclist. We use the p_hash member to linkup to deadproc. 339 */ 340 struct mutex deadproc_mutex = 341 MUTEX_INITIALIZER_FLAGS(IPL_NONE, NULL, MTX_NOWITNESS); 342 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 343 344 /* 345 * We are called from cpu_exit() once it is safe to schedule the 346 * dead process's resources to be freed. 347 * 348 * NOTE: One must be careful with locking in this routine. It's 349 * called from a critical section in machine-dependent code, so 350 * we should refrain from changing any interrupt state. 351 * 352 * We lock the deadproc list, place the proc on that list (using 353 * the p_hash member), and wake up the reaper. 354 */ 355 void 356 exit2(struct proc *p) 357 { 358 mtx_enter(&deadproc_mutex); 359 LIST_INSERT_HEAD(&deadproc, p, p_hash); 360 mtx_leave(&deadproc_mutex); 361 362 wakeup(&deadproc); 363 } 364 365 void 366 proc_free(struct proc *p) 367 { 368 crfree(p->p_ucred); 369 pool_put(&proc_pool, p); 370 nthreads--; 371 } 372 373 /* 374 * Process reaper. This is run by a kernel thread to free the resources 375 * of a dead process. Once the resources are free, the process becomes 376 * a zombie, and the parent is allowed to read the undead's status. 377 */ 378 void 379 reaper(void) 380 { 381 struct proc *p; 382 383 KERNEL_UNLOCK(); 384 385 SCHED_ASSERT_UNLOCKED(); 386 387 for (;;) { 388 mtx_enter(&deadproc_mutex); 389 while ((p = LIST_FIRST(&deadproc)) == NULL) 390 msleep(&deadproc, &deadproc_mutex, PVM, "reaper", 0); 391 392 /* Remove us from the deadproc list. */ 393 LIST_REMOVE(p, p_hash); 394 mtx_leave(&deadproc_mutex); 395 396 WITNESS_THREAD_EXIT(p); 397 398 KERNEL_LOCK(); 399 400 /* 401 * Free the VM resources we're still holding on to. 402 * We must do this from a valid thread because doing 403 * so may block. 404 */ 405 uvm_uarea_free(p); 406 p->p_vmspace = NULL; /* zap the thread's copy */ 407 408 if (p->p_flag & P_THREAD) { 409 /* Just a thread */ 410 proc_free(p); 411 } else { 412 struct process *pr = p->p_p; 413 414 /* Release the rest of the process's vmspace */ 415 uvm_exit(pr); 416 417 if ((pr->ps_flags & PS_NOZOMBIE) == 0) { 418 /* Process is now a true zombie. */ 419 atomic_setbits_int(&pr->ps_flags, PS_ZOMBIE); 420 prsignal(pr->ps_pptr, SIGCHLD); 421 422 /* Wake up the parent so it can get exit status. */ 423 wakeup(pr->ps_pptr); 424 } else { 425 /* No one will wait for us. Just zap the process now */ 426 process_zap(pr); 427 } 428 } 429 430 KERNEL_UNLOCK(); 431 } 432 } 433 434 int 435 sys_wait4(struct proc *q, void *v, register_t *retval) 436 { 437 struct sys_wait4_args /* { 438 syscallarg(pid_t) pid; 439 syscallarg(int *) status; 440 syscallarg(int) options; 441 syscallarg(struct rusage *) rusage; 442 } */ *uap = v; 443 struct rusage ru; 444 int status, error; 445 446 error = dowait4(q, SCARG(uap, pid), 447 SCARG(uap, status) ? &status : NULL, 448 SCARG(uap, options), SCARG(uap, rusage) ? &ru : NULL, retval); 449 if (error == 0 && retval[0] > 0 && SCARG(uap, status)) { 450 error = copyout(&status, SCARG(uap, status), sizeof(status)); 451 } 452 if (error == 0 && retval[0] > 0 && SCARG(uap, rusage)) { 453 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru)); 454 #ifdef KTRACE 455 if (error == 0 && KTRPOINT(q, KTR_STRUCT)) 456 ktrrusage(q, &ru); 457 #endif 458 } 459 return (error); 460 } 461 462 int 463 dowait4(struct proc *q, pid_t pid, int *statusp, int options, 464 struct rusage *rusage, register_t *retval) 465 { 466 int nfound; 467 struct process *pr; 468 struct proc *p; 469 int error; 470 471 if (pid == 0) 472 pid = -q->p_p->ps_pgid; 473 if (options &~ (WUNTRACED|WNOHANG|WCONTINUED)) 474 return (EINVAL); 475 476 loop: 477 nfound = 0; 478 LIST_FOREACH(pr, &q->p_p->ps_children, ps_sibling) { 479 if ((pr->ps_flags & PS_NOZOMBIE) || 480 (pid != WAIT_ANY && 481 pr->ps_pid != pid && 482 pr->ps_pgid != -pid)) 483 continue; 484 485 p = pr->ps_mainproc; 486 487 nfound++; 488 if (pr->ps_flags & PS_ZOMBIE) { 489 retval[0] = pr->ps_pid; 490 491 if (statusp != NULL) 492 *statusp = p->p_xstat; /* convert to int */ 493 if (rusage != NULL) 494 memcpy(rusage, pr->ps_ru, sizeof(*rusage)); 495 proc_finish_wait(q, p); 496 return (0); 497 } 498 if (pr->ps_flags & PS_TRACED && 499 (pr->ps_flags & PS_WAITED) == 0 && pr->ps_single && 500 pr->ps_single->p_stat == SSTOP && 501 (pr->ps_single->p_flag & P_SUSPSINGLE) == 0) { 502 single_thread_wait(pr); 503 504 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 505 retval[0] = pr->ps_pid; 506 507 if (statusp != NULL) 508 *statusp = W_STOPCODE(pr->ps_single->p_xstat); 509 if (rusage != NULL) 510 memset(rusage, 0, sizeof(*rusage)); 511 return (0); 512 } 513 if (p->p_stat == SSTOP && 514 (pr->ps_flags & PS_WAITED) == 0 && 515 (p->p_flag & P_SUSPSINGLE) == 0 && 516 (pr->ps_flags & PS_TRACED || 517 options & WUNTRACED)) { 518 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 519 retval[0] = pr->ps_pid; 520 521 if (statusp != NULL) 522 *statusp = W_STOPCODE(p->p_xstat); 523 if (rusage != NULL) 524 memset(rusage, 0, sizeof(*rusage)); 525 return (0); 526 } 527 if ((options & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 528 atomic_clearbits_int(&p->p_flag, P_CONTINUED); 529 retval[0] = pr->ps_pid; 530 531 if (statusp != NULL) 532 *statusp = _WCONTINUED; 533 if (rusage != NULL) 534 memset(rusage, 0, sizeof(*rusage)); 535 return (0); 536 } 537 } 538 if (nfound == 0) 539 return (ECHILD); 540 if (options & WNOHANG) { 541 retval[0] = 0; 542 return (0); 543 } 544 if ((error = tsleep(q->p_p, PWAIT | PCATCH, "wait", 0)) != 0) 545 return (error); 546 goto loop; 547 } 548 549 void 550 proc_finish_wait(struct proc *waiter, struct proc *p) 551 { 552 struct process *pr, *tr; 553 struct rusage *rup; 554 555 /* 556 * If we got the child via a ptrace 'attach', 557 * we need to give it back to the old parent. 558 */ 559 pr = p->p_p; 560 if (pr->ps_oppid && (tr = prfind(pr->ps_oppid))) { 561 atomic_clearbits_int(&pr->ps_flags, PS_TRACED); 562 pr->ps_oppid = 0; 563 proc_reparent(pr, tr); 564 prsignal(tr, SIGCHLD); 565 wakeup(tr); 566 } else { 567 scheduler_wait_hook(waiter, p); 568 p->p_xstat = 0; 569 rup = &waiter->p_p->ps_cru; 570 ruadd(rup, pr->ps_ru); 571 LIST_REMOVE(pr, ps_list); /* off zombprocess */ 572 freepid(pr->ps_pid); 573 process_zap(pr); 574 } 575 } 576 577 /* 578 * make process 'parent' the new parent of process 'child'. 579 */ 580 void 581 proc_reparent(struct process *child, struct process *parent) 582 { 583 584 if (child->ps_pptr == parent) 585 return; 586 587 LIST_REMOVE(child, ps_sibling); 588 LIST_INSERT_HEAD(&parent->ps_children, child, ps_sibling); 589 child->ps_pptr = parent; 590 } 591 592 void 593 process_zap(struct process *pr) 594 { 595 struct vnode *otvp; 596 struct proc *p = pr->ps_mainproc; 597 598 /* 599 * Finally finished with old proc entry. 600 * Unlink it from its process group and free it. 601 */ 602 leavepgrp(pr); 603 LIST_REMOVE(pr, ps_sibling); 604 605 /* 606 * Decrement the count of procs running with this uid. 607 */ 608 (void)chgproccnt(pr->ps_ucred->cr_ruid, -1); 609 610 unveil_destroy(pr); 611 612 /* 613 * Release reference to text vnode 614 */ 615 otvp = pr->ps_textvp; 616 pr->ps_textvp = NULL; 617 if (otvp) 618 vrele(otvp); 619 620 KASSERT(pr->ps_refcnt == 1); 621 if (pr->ps_ptstat != NULL) 622 free(pr->ps_ptstat, M_SUBPROC, sizeof(*pr->ps_ptstat)); 623 pool_put(&rusage_pool, pr->ps_ru); 624 KASSERT(TAILQ_EMPTY(&pr->ps_threads)); 625 limfree(pr->ps_limit); 626 crfree(pr->ps_ucred); 627 pool_put(&process_pool, pr); 628 nprocesses--; 629 630 proc_free(p); 631 } 632