1 /* $OpenBSD: kern_exit.c,v 1.164 2018/02/10 10:32:51 mpi 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 77 /* 78 * exit -- 79 * Death of process. 80 */ 81 int 82 sys_exit(struct proc *p, void *v, register_t *retval) 83 { 84 struct sys_exit_args /* { 85 syscallarg(int) rval; 86 } */ *uap = v; 87 88 exit1(p, W_EXITCODE(SCARG(uap, rval), 0), EXIT_NORMAL); 89 /* NOTREACHED */ 90 return (0); 91 } 92 93 int 94 sys___threxit(struct proc *p, void *v, register_t *retval) 95 { 96 struct sys___threxit_args /* { 97 syscallarg(pid_t *) notdead; 98 } */ *uap = v; 99 100 if (SCARG(uap, notdead) != NULL) { 101 pid_t zero = 0; 102 if (copyout(&zero, SCARG(uap, notdead), sizeof(zero))) 103 psignal(p, SIGSEGV); 104 } 105 exit1(p, 0, EXIT_THREAD); 106 107 return (0); 108 } 109 110 /* 111 * Exit: deallocate address space and other resources, change proc state 112 * to zombie, and unlink proc from allproc and parent's lists. Save exit 113 * status and rusage for wait(). Check for child processes and orphan them. 114 */ 115 void 116 exit1(struct proc *p, int rv, int flags) 117 { 118 struct process *pr, *qr, *nqr; 119 struct rusage *rup; 120 121 atomic_setbits_int(&p->p_flag, P_WEXIT); 122 123 pr = p->p_p; 124 125 /* single-threaded? */ 126 if (!P_HASSIBLING(p)) { 127 flags = EXIT_NORMAL; 128 } else { 129 /* nope, multi-threaded */ 130 if (flags == EXIT_NORMAL) 131 single_thread_set(p, SINGLE_EXIT, 0); 132 else if (flags == EXIT_THREAD) 133 single_thread_check(p, 0); 134 } 135 136 if (flags == EXIT_NORMAL) { 137 if (pr->ps_pid == 1) 138 panic("init died (signal %d, exit %d)", 139 WTERMSIG(rv), WEXITSTATUS(rv)); 140 141 atomic_setbits_int(&pr->ps_flags, PS_EXITING); 142 pr->ps_mainproc->p_xstat = rv; 143 144 /* 145 * If parent is waiting for us to exit or exec, PS_PPWAIT 146 * is set; we wake up the parent early to avoid deadlock. 147 */ 148 if (pr->ps_flags & PS_PPWAIT) { 149 atomic_clearbits_int(&pr->ps_flags, PS_PPWAIT); 150 atomic_clearbits_int(&pr->ps_pptr->ps_flags, 151 PS_ISPWAIT); 152 wakeup(pr->ps_pptr); 153 } 154 } 155 156 /* unlink ourselves from the active threads */ 157 TAILQ_REMOVE(&pr->ps_threads, p, p_thr_link); 158 if ((p->p_flag & P_THREAD) == 0) { 159 /* main thread gotta wait because it has the pid, et al */ 160 while (pr->ps_refcnt > 1) 161 tsleep(&pr->ps_threads, PUSER, "thrdeath", 0); 162 if (pr->ps_flags & PS_PROFIL) 163 stopprofclock(pr); 164 } 165 166 rup = pr->ps_ru; 167 if (rup == NULL) { 168 rup = pool_get(&rusage_pool, PR_WAITOK | PR_ZERO); 169 if (pr->ps_ru == NULL) { 170 pr->ps_ru = rup; 171 } else { 172 pool_put(&rusage_pool, rup); 173 rup = pr->ps_ru; 174 } 175 } 176 p->p_siglist = 0; 177 178 if ((p->p_flag & P_THREAD) == 0) { 179 /* close open files and release open-file table */ 180 fdfree(p); 181 182 timeout_del(&pr->ps_realit_to); 183 #ifdef SYSVSEM 184 semexit(pr); 185 #endif 186 killjobc(pr); 187 #ifdef ACCOUNTING 188 acct_process(p); 189 #endif 190 191 #ifdef KTRACE 192 /* release trace file */ 193 if (pr->ps_tracevp) 194 ktrcleartrace(pr); 195 #endif 196 197 /* 198 * If parent has the SAS_NOCLDWAIT flag set, we're not 199 * going to become a zombie. 200 */ 201 if (pr->ps_pptr->ps_sigacts->ps_flags & SAS_NOCLDWAIT) 202 atomic_setbits_int(&pr->ps_flags, PS_NOZOMBIE); 203 } 204 205 p->p_fd = NULL; /* zap the thread's copy */ 206 207 /* 208 * Remove proc from pidhash chain and allproc so looking 209 * it up won't work. We will put the proc on the 210 * deadproc list later (using the p_hash member), and 211 * wake up the reaper when we do. If this is the last 212 * thread of a process that isn't PS_NOZOMBIE, we'll put 213 * the process on the zombprocess list below. 214 */ 215 /* 216 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 217 */ 218 p->p_stat = SDEAD; 219 220 LIST_REMOVE(p, p_hash); 221 LIST_REMOVE(p, p_list); 222 223 if ((p->p_flag & P_THREAD) == 0) { 224 LIST_REMOVE(pr, ps_hash); 225 LIST_REMOVE(pr, ps_list); 226 227 if ((pr->ps_flags & PS_NOZOMBIE) == 0) 228 LIST_INSERT_HEAD(&zombprocess, pr, ps_list); 229 else { 230 /* 231 * Not going to be a zombie, so it's now off all 232 * the lists scanned by ispidtaken(), so block 233 * fast reuse of the pid now. 234 */ 235 freepid(pr->ps_pid); 236 } 237 238 /* 239 * Give orphaned children to init(8). 240 */ 241 qr = LIST_FIRST(&pr->ps_children); 242 if (qr) /* only need this if any child is S_ZOMB */ 243 wakeup(initprocess); 244 for (; qr != 0; qr = nqr) { 245 nqr = LIST_NEXT(qr, ps_sibling); 246 proc_reparent(qr, initprocess); 247 /* 248 * Traced processes are killed since their 249 * existence means someone is screwing up. 250 */ 251 if (qr->ps_flags & PS_TRACED && 252 !(qr->ps_flags & PS_EXITING)) { 253 atomic_clearbits_int(&qr->ps_flags, PS_TRACED); 254 /* 255 * If single threading is active, 256 * direct the signal to the active 257 * thread to avoid deadlock. 258 */ 259 if (qr->ps_single) 260 ptsignal(qr->ps_single, SIGKILL, 261 STHREAD); 262 else 263 prsignal(qr, SIGKILL); 264 } 265 } 266 } 267 268 /* add thread's accumulated rusage into the process's total */ 269 ruadd(rup, &p->p_ru); 270 tuagg(pr, p); 271 272 /* 273 * clear %cpu usage during swap 274 */ 275 p->p_pctcpu = 0; 276 277 if ((p->p_flag & P_THREAD) == 0) { 278 /* 279 * Final thread has died, so add on our children's rusage 280 * and calculate the total times 281 */ 282 calcru(&pr->ps_tu, &rup->ru_utime, &rup->ru_stime, NULL); 283 ruadd(rup, &pr->ps_cru); 284 285 /* notify interested parties of our demise and clean up */ 286 knote_processexit(p); 287 288 /* 289 * Notify parent that we're gone. If we're not going to 290 * become a zombie, reparent to process 1 (init) so that 291 * we can wake our original parent to possibly unblock 292 * wait4() to return ECHILD. 293 */ 294 if (pr->ps_flags & PS_NOZOMBIE) { 295 struct process *ppr = pr->ps_pptr; 296 proc_reparent(pr, initprocess); 297 wakeup(ppr); 298 } 299 300 /* 301 * Release the process's signal state. 302 */ 303 sigactsfree(pr); 304 } 305 306 /* just a thread? detach it from its process */ 307 if (p->p_flag & P_THREAD) { 308 /* scheduler_wait_hook(pr->ps_mainproc, p); XXX */ 309 if (--pr->ps_refcnt == 1) 310 wakeup(&pr->ps_threads); 311 KASSERT(pr->ps_refcnt > 0); 312 } 313 314 /* 315 * Other substructures are freed from reaper and wait(). 316 */ 317 318 /* 319 * Finally, call machine-dependent code to switch to a new 320 * context (possibly the idle context). Once we are no longer 321 * using the dead process's vmspace and stack, exit2() will be 322 * called to schedule those resources to be released by the 323 * reaper thread. 324 * 325 * Note that cpu_exit() will end with a call equivalent to 326 * cpu_switch(), finishing our execution (pun intended). 327 */ 328 uvmexp.swtch++; 329 cpu_exit(p); 330 panic("cpu_exit returned"); 331 } 332 333 /* 334 * Locking of this proclist is special; it's accessed in a 335 * critical section of process exit, and thus locking it can't 336 * modify interrupt state. We use a simple spin lock for this 337 * proclist. We use the p_hash member to linkup to deadproc. 338 */ 339 struct mutex deadproc_mutex = 340 MUTEX_INITIALIZER_FLAGS(IPL_NONE, NULL, MTX_NOWITNESS); 341 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 342 343 /* 344 * We are called from cpu_exit() once it is safe to schedule the 345 * dead process's resources to be freed. 346 * 347 * NOTE: One must be careful with locking in this routine. It's 348 * called from a critical section in machine-dependent code, so 349 * we should refrain from changing any interrupt state. 350 * 351 * We lock the deadproc list, place the proc on that list (using 352 * the p_hash member), and wake up the reaper. 353 */ 354 void 355 exit2(struct proc *p) 356 { 357 mtx_enter(&deadproc_mutex); 358 LIST_INSERT_HEAD(&deadproc, p, p_hash); 359 mtx_leave(&deadproc_mutex); 360 361 wakeup(&deadproc); 362 } 363 364 void 365 proc_free(struct proc *p) 366 { 367 crfree(p->p_ucred); 368 pool_put(&proc_pool, p); 369 nthreads--; 370 } 371 372 /* 373 * Process reaper. This is run by a kernel thread to free the resources 374 * of a dead process. Once the resources are free, the process becomes 375 * a zombie, and the parent is allowed to read the undead's status. 376 */ 377 void 378 reaper(void) 379 { 380 struct proc *p; 381 382 KERNEL_UNLOCK(); 383 384 SCHED_ASSERT_UNLOCKED(); 385 386 for (;;) { 387 mtx_enter(&deadproc_mutex); 388 while ((p = LIST_FIRST(&deadproc)) == NULL) 389 msleep(&deadproc, &deadproc_mutex, PVM, "reaper", 0); 390 391 /* Remove us from the deadproc list. */ 392 LIST_REMOVE(p, p_hash); 393 mtx_leave(&deadproc_mutex); 394 395 WITNESS_THREAD_EXIT(p); 396 397 KERNEL_LOCK(); 398 399 /* 400 * Free the VM resources we're still holding on to. 401 * We must do this from a valid thread because doing 402 * so may block. 403 */ 404 uvm_uarea_free(p); 405 p->p_vmspace = NULL; /* zap the thread's copy */ 406 407 if (p->p_flag & P_THREAD) { 408 /* Just a thread */ 409 proc_free(p); 410 } else { 411 struct process *pr = p->p_p; 412 413 /* Release the rest of the process's vmspace */ 414 uvm_exit(pr); 415 416 if ((pr->ps_flags & PS_NOZOMBIE) == 0) { 417 /* Process is now a true zombie. */ 418 atomic_setbits_int(&pr->ps_flags, PS_ZOMBIE); 419 prsignal(pr->ps_pptr, SIGCHLD); 420 421 /* Wake up the parent so it can get exit status. */ 422 wakeup(pr->ps_pptr); 423 } else { 424 /* No one will wait for us. Just zap the process now */ 425 process_zap(pr); 426 } 427 } 428 429 KERNEL_UNLOCK(); 430 } 431 } 432 433 int 434 sys_wait4(struct proc *q, void *v, register_t *retval) 435 { 436 struct sys_wait4_args /* { 437 syscallarg(pid_t) pid; 438 syscallarg(int *) status; 439 syscallarg(int) options; 440 syscallarg(struct rusage *) rusage; 441 } */ *uap = v; 442 struct rusage ru; 443 int status, error; 444 445 error = dowait4(q, SCARG(uap, pid), 446 SCARG(uap, status) ? &status : NULL, 447 SCARG(uap, options), SCARG(uap, rusage) ? &ru : NULL, retval); 448 if (error == 0 && retval[0] > 0 && SCARG(uap, status)) { 449 error = copyout(&status, SCARG(uap, status), sizeof(status)); 450 } 451 if (error == 0 && retval[0] > 0 && SCARG(uap, rusage)) { 452 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru)); 453 #ifdef KTRACE 454 if (error == 0 && KTRPOINT(q, KTR_STRUCT)) 455 ktrrusage(q, &ru); 456 #endif 457 } 458 return (error); 459 } 460 461 int 462 dowait4(struct proc *q, pid_t pid, int *statusp, int options, 463 struct rusage *rusage, register_t *retval) 464 { 465 int nfound; 466 struct process *pr; 467 struct proc *p; 468 int error; 469 470 if (pid == 0) 471 pid = -q->p_p->ps_pgid; 472 if (options &~ (WUNTRACED|WNOHANG|WCONTINUED)) 473 return (EINVAL); 474 475 loop: 476 nfound = 0; 477 LIST_FOREACH(pr, &q->p_p->ps_children, ps_sibling) { 478 if ((pr->ps_flags & PS_NOZOMBIE) || 479 (pid != WAIT_ANY && 480 pr->ps_pid != pid && 481 pr->ps_pgid != -pid)) 482 continue; 483 484 p = pr->ps_mainproc; 485 486 nfound++; 487 if (pr->ps_flags & PS_ZOMBIE) { 488 retval[0] = pr->ps_pid; 489 490 if (statusp != NULL) 491 *statusp = p->p_xstat; /* convert to int */ 492 if (rusage != NULL) 493 memcpy(rusage, pr->ps_ru, sizeof(*rusage)); 494 proc_finish_wait(q, p); 495 return (0); 496 } 497 if (pr->ps_flags & PS_TRACED && 498 (pr->ps_flags & PS_WAITED) == 0 && pr->ps_single && 499 pr->ps_single->p_stat == SSTOP && 500 (pr->ps_single->p_flag & P_SUSPSINGLE) == 0) { 501 single_thread_wait(pr); 502 503 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 504 retval[0] = pr->ps_pid; 505 506 if (statusp != NULL) 507 *statusp = W_STOPCODE(pr->ps_single->p_xstat); 508 if (rusage != NULL) 509 memset(rusage, 0, sizeof(*rusage)); 510 return (0); 511 } 512 if (p->p_stat == SSTOP && 513 (pr->ps_flags & PS_WAITED) == 0 && 514 (p->p_flag & P_SUSPSINGLE) == 0 && 515 (pr->ps_flags & PS_TRACED || 516 options & WUNTRACED)) { 517 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 518 retval[0] = pr->ps_pid; 519 520 if (statusp != NULL) 521 *statusp = W_STOPCODE(p->p_xstat); 522 if (rusage != NULL) 523 memset(rusage, 0, sizeof(*rusage)); 524 return (0); 525 } 526 if ((options & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 527 atomic_clearbits_int(&p->p_flag, P_CONTINUED); 528 retval[0] = pr->ps_pid; 529 530 if (statusp != NULL) 531 *statusp = _WCONTINUED; 532 if (rusage != NULL) 533 memset(rusage, 0, sizeof(*rusage)); 534 return (0); 535 } 536 } 537 if (nfound == 0) 538 return (ECHILD); 539 if (options & WNOHANG) { 540 retval[0] = 0; 541 return (0); 542 } 543 if ((error = tsleep(q->p_p, PWAIT | PCATCH, "wait", 0)) != 0) 544 return (error); 545 goto loop; 546 } 547 548 void 549 proc_finish_wait(struct proc *waiter, struct proc *p) 550 { 551 struct process *pr, *tr; 552 struct rusage *rup; 553 554 /* 555 * If we got the child via a ptrace 'attach', 556 * we need to give it back to the old parent. 557 */ 558 pr = p->p_p; 559 if (pr->ps_oppid && (tr = prfind(pr->ps_oppid))) { 560 atomic_clearbits_int(&pr->ps_flags, PS_TRACED); 561 pr->ps_oppid = 0; 562 proc_reparent(pr, tr); 563 prsignal(tr, SIGCHLD); 564 wakeup(tr); 565 } else { 566 scheduler_wait_hook(waiter, p); 567 p->p_xstat = 0; 568 rup = &waiter->p_p->ps_cru; 569 ruadd(rup, pr->ps_ru); 570 LIST_REMOVE(pr, ps_list); /* off zombprocess */ 571 freepid(pr->ps_pid); 572 process_zap(pr); 573 } 574 } 575 576 /* 577 * make process 'parent' the new parent of process 'child'. 578 */ 579 void 580 proc_reparent(struct process *child, struct process *parent) 581 { 582 583 if (child->ps_pptr == parent) 584 return; 585 586 LIST_REMOVE(child, ps_sibling); 587 LIST_INSERT_HEAD(&parent->ps_children, child, ps_sibling); 588 child->ps_pptr = parent; 589 } 590 591 void 592 process_zap(struct process *pr) 593 { 594 struct vnode *otvp; 595 struct proc *p = pr->ps_mainproc; 596 597 /* 598 * Finally finished with old proc entry. 599 * Unlink it from its process group and free it. 600 */ 601 leavepgrp(pr); 602 LIST_REMOVE(pr, ps_sibling); 603 604 /* 605 * Decrement the count of procs running with this uid. 606 */ 607 (void)chgproccnt(pr->ps_ucred->cr_ruid, -1); 608 609 /* 610 * Release reference to text vnode 611 */ 612 otvp = pr->ps_textvp; 613 pr->ps_textvp = NULL; 614 if (otvp) 615 vrele(otvp); 616 617 KASSERT(pr->ps_refcnt == 1); 618 if (pr->ps_ptstat != NULL) 619 free(pr->ps_ptstat, M_SUBPROC, sizeof(*pr->ps_ptstat)); 620 pool_put(&rusage_pool, pr->ps_ru); 621 KASSERT(TAILQ_EMPTY(&pr->ps_threads)); 622 limfree(pr->ps_limit); 623 crfree(pr->ps_ucred); 624 pool_put(&process_pool, pr); 625 nprocesses--; 626 627 proc_free(p); 628 } 629