1 /* 2 * Copyright (c) 1982, 1986, 1989, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * @(#)kern_exit.c 8.7 (Berkeley) 2/12/94 39 * $FreeBSD: src/sys/kern/kern_exit.c,v 1.92.2.11 2003/01/13 22:51:16 dillon Exp $ 40 * $DragonFly: src/sys/kern/kern_exit.c,v 1.91 2008/05/18 20:02:02 nth Exp $ 41 */ 42 43 #include "opt_compat.h" 44 #include "opt_ktrace.h" 45 46 #include <sys/param.h> 47 #include <sys/systm.h> 48 #include <sys/sysproto.h> 49 #include <sys/kernel.h> 50 #include <sys/malloc.h> 51 #include <sys/proc.h> 52 #include <sys/ktrace.h> 53 #include <sys/pioctl.h> 54 #include <sys/tty.h> 55 #include <sys/wait.h> 56 #include <sys/vnode.h> 57 #include <sys/resourcevar.h> 58 #include <sys/signalvar.h> 59 #include <sys/taskqueue.h> 60 #include <sys/ptrace.h> 61 #include <sys/acct.h> /* for acct_process() function prototype */ 62 #include <sys/filedesc.h> 63 #include <sys/shm.h> 64 #include <sys/sem.h> 65 #include <sys/aio.h> 66 #include <sys/jail.h> 67 #include <sys/kern_syscall.h> 68 #include <sys/upcall.h> 69 #include <sys/caps.h> 70 #include <sys/unistd.h> 71 72 #include <vm/vm.h> 73 #include <vm/vm_param.h> 74 #include <sys/lock.h> 75 #include <vm/pmap.h> 76 #include <vm/vm_map.h> 77 #include <vm/vm_extern.h> 78 #include <sys/user.h> 79 80 #include <sys/thread2.h> 81 #include <sys/sysref2.h> 82 83 static void reaplwps(void *context, int dummy); 84 static void reaplwp(struct lwp *lp); 85 static void killlwps(struct lwp *lp); 86 87 static MALLOC_DEFINE(M_ATEXIT, "atexit", "atexit callback"); 88 static MALLOC_DEFINE(M_ZOMBIE, "zombie", "zombie proc status"); 89 90 /* 91 * callout list for things to do at exit time 92 */ 93 struct exitlist { 94 exitlist_fn function; 95 TAILQ_ENTRY(exitlist) next; 96 }; 97 98 TAILQ_HEAD(exit_list_head, exitlist); 99 static struct exit_list_head exit_list = TAILQ_HEAD_INITIALIZER(exit_list); 100 101 /* 102 * LWP reaper data 103 */ 104 struct task *deadlwp_task[MAXCPU]; 105 struct lwplist deadlwp_list[MAXCPU]; 106 107 /* 108 * exit -- 109 * Death of process. 110 * 111 * SYS_EXIT_ARGS(int rval) 112 * 113 * MPALMOSTSAFE 114 */ 115 int 116 sys_exit(struct exit_args *uap) 117 { 118 get_mplock(); 119 exit1(W_EXITCODE(uap->rval, 0)); 120 /* NOTREACHED */ 121 rel_mplock(); 122 } 123 124 /* 125 * Extended exit -- 126 * Death of a lwp or process with optional bells and whistles. 127 * 128 * MPALMOSTSAFE 129 */ 130 int 131 sys_extexit(struct extexit_args *uap) 132 { 133 int action, who; 134 int error; 135 136 action = EXTEXIT_ACTION(uap->how); 137 who = EXTEXIT_WHO(uap->how); 138 139 /* Check parameters before we might perform some action */ 140 switch (who) { 141 case EXTEXIT_PROC: 142 case EXTEXIT_LWP: 143 break; 144 default: 145 return (EINVAL); 146 } 147 148 switch (action) { 149 case EXTEXIT_SIMPLE: 150 break; 151 case EXTEXIT_SETINT: 152 error = copyout(&uap->status, uap->addr, sizeof(uap->status)); 153 if (error) 154 return (error); 155 break; 156 default: 157 return (EINVAL); 158 } 159 160 get_mplock(); 161 162 switch (who) { 163 case EXTEXIT_LWP: 164 /* 165 * Be sure only to perform a simple lwp exit if there is at 166 * least one more lwp in the proc, which will call exit1() 167 * later, otherwise the proc will be an UNDEAD and not even a 168 * SZOMB! 169 */ 170 if (curproc->p_nthreads > 1) { 171 lwp_exit(0); 172 /* NOT REACHED */ 173 } 174 /* else last lwp in proc: do the real thing */ 175 /* FALLTHROUGH */ 176 default: /* to help gcc */ 177 case EXTEXIT_PROC: 178 exit1(W_EXITCODE(uap->status, 0)); 179 /* NOTREACHED */ 180 } 181 182 /* NOTREACHED */ 183 rel_mplock(); /* safety */ 184 } 185 186 /* 187 * Kill all lwps associated with the current process except the 188 * current lwp. Return an error if we race another thread trying to 189 * do the same thing and lose the race. 190 * 191 * If forexec is non-zero the current thread and process flags are 192 * cleaned up so they can be reused. 193 */ 194 int 195 killalllwps(int forexec) 196 { 197 struct lwp *lp = curthread->td_lwp; 198 struct proc *p = lp->lwp_proc; 199 200 /* 201 * Interlock against P_WEXIT. Only one of the process's thread 202 * is allowed to do the master exit. 203 */ 204 if (p->p_flag & P_WEXIT) 205 return (EALREADY); 206 p->p_flag |= P_WEXIT; 207 208 /* 209 * Interlock with LWP_WEXIT and kill any remaining LWPs 210 */ 211 lp->lwp_flag |= LWP_WEXIT; 212 if (p->p_nthreads > 1) 213 killlwps(lp); 214 215 /* 216 * If doing this for an exec, clean up the remaining thread 217 * (us) for continuing operation after all the other threads 218 * have been killed. 219 */ 220 if (forexec) { 221 lp->lwp_flag &= ~LWP_WEXIT; 222 p->p_flag &= ~P_WEXIT; 223 } 224 return(0); 225 } 226 227 /* 228 * Kill all LWPs except the current one. Do not try to signal 229 * LWPs which have exited on their own or have already been 230 * signaled. 231 */ 232 static void 233 killlwps(struct lwp *lp) 234 { 235 struct proc *p = lp->lwp_proc; 236 struct lwp *tlp; 237 238 /* 239 * Kill the remaining LWPs. We must send the signal before setting 240 * LWP_WEXIT. The setting of WEXIT is optional but helps reduce 241 * races. tlp must be held across the call as it might block and 242 * allow the target lwp to rip itself out from under our loop. 243 */ 244 FOREACH_LWP_IN_PROC(tlp, p) { 245 LWPHOLD(tlp); 246 if ((tlp->lwp_flag & LWP_WEXIT) == 0) { 247 lwpsignal(p, tlp, SIGKILL); 248 tlp->lwp_flag |= LWP_WEXIT; 249 } 250 LWPRELE(tlp); 251 } 252 253 /* 254 * Wait for everything to clear out. 255 */ 256 while (p->p_nthreads > 1) { 257 tsleep(&p->p_nthreads, 0, "killlwps", 0); 258 } 259 } 260 261 /* 262 * Exit: deallocate address space and other resources, change proc state 263 * to zombie, and unlink proc from allproc and parent's lists. Save exit 264 * status and rusage for wait(). Check for child processes and orphan them. 265 */ 266 void 267 exit1(int rv) 268 { 269 struct thread *td = curthread; 270 struct proc *p = td->td_proc; 271 struct lwp *lp = td->td_lwp; 272 struct proc *q, *nq; 273 struct vmspace *vm; 274 struct vnode *vtmp; 275 struct exitlist *ep; 276 int error; 277 278 if (p->p_pid == 1) { 279 kprintf("init died (signal %d, exit %d)\n", 280 WTERMSIG(rv), WEXITSTATUS(rv)); 281 panic("Going nowhere without my init!"); 282 } 283 284 varsymset_clean(&p->p_varsymset); 285 lockuninit(&p->p_varsymset.vx_lock); 286 /* 287 * Kill all lwps associated with the current process, return an 288 * error if we race another thread trying to do the same thing 289 * and lose the race. 290 */ 291 error = killalllwps(0); 292 if (error) { 293 lwp_exit(0); 294 /* NOT REACHED */ 295 } 296 297 caps_exit(lp->lwp_thread); 298 aio_proc_rundown(p); 299 300 /* are we a task leader? */ 301 if (p == p->p_leader) { 302 struct kill_args killArgs; 303 killArgs.signum = SIGKILL; 304 q = p->p_peers; 305 while(q) { 306 killArgs.pid = q->p_pid; 307 /* 308 * The interface for kill is better 309 * than the internal signal 310 */ 311 sys_kill(&killArgs); 312 nq = q; 313 q = q->p_peers; 314 } 315 while (p->p_peers) 316 tsleep((caddr_t)p, 0, "exit1", 0); 317 } 318 319 #ifdef PGINPROF 320 vmsizmon(); 321 #endif 322 STOPEVENT(p, S_EXIT, rv); 323 wakeup(&p->p_stype); /* Wakeup anyone in procfs' PIOCWAIT */ 324 325 /* 326 * Check if any loadable modules need anything done at process exit. 327 * e.g. SYSV IPC stuff 328 * XXX what if one of these generates an error? 329 */ 330 TAILQ_FOREACH(ep, &exit_list, next) 331 (*ep->function)(td); 332 333 if (p->p_flag & P_PROFIL) 334 stopprofclock(p); 335 /* 336 * If parent is waiting for us to exit or exec, 337 * P_PPWAIT is set; we will wakeup the parent below. 338 */ 339 p->p_flag &= ~(P_TRACED | P_PPWAIT); 340 SIGEMPTYSET(p->p_siglist); 341 SIGEMPTYSET(lp->lwp_siglist); 342 if (timevalisset(&p->p_realtimer.it_value)) 343 callout_stop(&p->p_ithandle); 344 345 /* 346 * Reset any sigio structures pointing to us as a result of 347 * F_SETOWN with our pid. 348 */ 349 funsetownlst(&p->p_sigiolst); 350 351 /* 352 * Close open files and release open-file table. 353 * This may block! 354 */ 355 fdfree(p, NULL); 356 357 if(p->p_leader->p_peers) { 358 q = p->p_leader; 359 while(q->p_peers != p) 360 q = q->p_peers; 361 q->p_peers = p->p_peers; 362 wakeup((caddr_t)p->p_leader); 363 } 364 365 /* 366 * XXX Shutdown SYSV semaphores 367 */ 368 semexit(p); 369 370 KKASSERT(p->p_numposixlocks == 0); 371 372 /* The next two chunks should probably be moved to vmspace_exit. */ 373 vm = p->p_vmspace; 374 375 /* 376 * Release upcalls associated with this process 377 */ 378 if (vm->vm_upcalls) 379 upc_release(vm, lp); 380 381 /* 382 * Clean up data related to virtual kernel operation. Clean up 383 * any vkernel context related to the current lwp now so we can 384 * destroy p_vkernel. 385 */ 386 if (p->p_vkernel) { 387 vkernel_lwp_exit(lp); 388 vkernel_exit(p); 389 } 390 391 /* 392 * Release user portion of address space. 393 * This releases references to vnodes, 394 * which could cause I/O if the file has been unlinked. 395 * Need to do this early enough that we can still sleep. 396 * Can't free the entire vmspace as the kernel stack 397 * may be mapped within that space also. 398 * 399 * Processes sharing the same vmspace may exit in one order, and 400 * get cleaned up by vmspace_exit() in a different order. The 401 * last exiting process to reach this point releases as much of 402 * the environment as it can, and the last process cleaned up 403 * by vmspace_exit() (which decrements exitingcnt) cleans up the 404 * remainder. 405 */ 406 ++vm->vm_exitingcnt; 407 sysref_put(&vm->vm_sysref); 408 409 if (SESS_LEADER(p)) { 410 struct session *sp = p->p_session; 411 412 if (sp->s_ttyvp) { 413 /* 414 * We are the controlling process. Signal the 415 * foreground process group, drain the controlling 416 * terminal, and revoke access to the controlling 417 * terminal. 418 * 419 * NOTE: while waiting for the process group to exit 420 * it is possible that one of the processes in the 421 * group will revoke the tty, so the ttyclosesession() 422 * function will re-check sp->s_ttyvp. 423 */ 424 if (sp->s_ttyp && (sp->s_ttyp->t_session == sp)) { 425 if (sp->s_ttyp->t_pgrp) 426 pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1); 427 ttywait(sp->s_ttyp); 428 ttyclosesession(sp, 1); /* also revoke */ 429 } 430 /* 431 * Release the tty. If someone has it open via 432 * /dev/tty then close it (since they no longer can 433 * once we've NULL'd it out). 434 */ 435 ttyclosesession(sp, 0); 436 437 /* 438 * s_ttyp is not zero'd; we use this to indicate 439 * that the session once had a controlling terminal. 440 * (for logging and informational purposes) 441 */ 442 } 443 sp->s_leader = NULL; 444 } 445 fixjobc(p, p->p_pgrp, 0); 446 (void)acct_process(p); 447 #ifdef KTRACE 448 /* 449 * release trace file 450 */ 451 if (p->p_tracenode) 452 ktrdestroy(&p->p_tracenode); 453 p->p_traceflag = 0; 454 #endif 455 /* 456 * Release reference to text vnode 457 */ 458 if ((vtmp = p->p_textvp) != NULL) { 459 p->p_textvp = NULL; 460 vrele(vtmp); 461 } 462 463 /* 464 * Move the process to the zombie list. This will block 465 * until the process p_lock count reaches 0. The process will 466 * not be reaped until TDF_EXITING is set by cpu_thread_exit(), 467 * which is called from cpu_proc_exit(). 468 */ 469 proc_move_allproc_zombie(p); 470 471 q = LIST_FIRST(&p->p_children); 472 if (q) /* only need this if any child is S_ZOMB */ 473 wakeup((caddr_t) initproc); 474 for (; q != 0; q = nq) { 475 nq = LIST_NEXT(q, p_sibling); 476 LIST_REMOVE(q, p_sibling); 477 LIST_INSERT_HEAD(&initproc->p_children, q, p_sibling); 478 q->p_pptr = initproc; 479 q->p_sigparent = SIGCHLD; 480 /* 481 * Traced processes are killed 482 * since their existence means someone is screwing up. 483 */ 484 if (q->p_flag & P_TRACED) { 485 q->p_flag &= ~P_TRACED; 486 ksignal(q, SIGKILL); 487 } 488 } 489 490 /* 491 * Save exit status and final rusage info, adding in child rusage 492 * info and self times. 493 */ 494 p->p_xstat = rv; 495 calcru_proc(p, &p->p_ru); 496 ruadd(&p->p_ru, &p->p_cru); 497 498 /* 499 * notify interested parties of our demise. 500 */ 501 KNOTE(&p->p_klist, NOTE_EXIT); 502 503 /* 504 * Notify parent that we're gone. If parent has the PS_NOCLDWAIT 505 * flag set, notify process 1 instead (and hope it will handle 506 * this situation). 507 */ 508 if (p->p_pptr->p_sigacts->ps_flag & PS_NOCLDWAIT) { 509 struct proc *pp = p->p_pptr; 510 proc_reparent(p, initproc); 511 /* 512 * If this was the last child of our parent, notify 513 * parent, so in case he was wait(2)ing, he will 514 * continue. 515 */ 516 if (LIST_EMPTY(&pp->p_children)) 517 wakeup((caddr_t)pp); 518 } 519 520 if (p->p_sigparent && p->p_pptr != initproc) { 521 ksignal(p->p_pptr, p->p_sigparent); 522 } else { 523 ksignal(p->p_pptr, SIGCHLD); 524 } 525 526 wakeup((caddr_t)p->p_pptr); 527 /* 528 * cpu_exit is responsible for clearing curproc, since 529 * it is heavily integrated with the thread/switching sequence. 530 * 531 * Other substructures are freed from wait(). 532 */ 533 plimit_free(p); 534 535 /* 536 * Release the current user process designation on the process so 537 * the userland scheduler can work in someone else. 538 */ 539 p->p_usched->release_curproc(lp); 540 541 /* 542 * Finally, call machine-dependent code to release as many of the 543 * lwp's resources as we can and halt execution of this thread. 544 */ 545 lwp_exit(1); 546 } 547 548 /* 549 * Eventually called by every exiting LWP 550 */ 551 void 552 lwp_exit(int masterexit) 553 { 554 struct thread *td = curthread; 555 struct lwp *lp = td->td_lwp; 556 struct proc *p = lp->lwp_proc; 557 558 /* 559 * lwp_exit() may be called without setting LWP_WEXIT, so 560 * make sure it is set here. 561 */ 562 lp->lwp_flag |= LWP_WEXIT; 563 564 /* 565 * Clean up any virtualization 566 */ 567 if (lp->lwp_vkernel) 568 vkernel_lwp_exit(lp); 569 570 /* 571 * Clean up any syscall-cached ucred 572 */ 573 if (td->td_ucred) { 574 crfree(td->td_ucred); 575 td->td_ucred = NULL; 576 } 577 578 /* 579 * Nobody actually wakes us when the lock 580 * count reaches zero, so just wait one tick. 581 */ 582 while (lp->lwp_lock > 0) 583 tsleep(lp, 0, "lwpexit", 1); 584 585 /* Hand down resource usage to our proc */ 586 ruadd(&p->p_ru, &lp->lwp_ru); 587 588 /* 589 * If we don't hold the process until the LWP is reaped wait*() 590 * may try to dispose of its vmspace before all the LWPs have 591 * actually terminated. 592 */ 593 PHOLD(p); 594 595 /* 596 * We have to use the reaper for all the LWPs except the one doing 597 * the master exit. The LWP doing the master exit can just be 598 * left on p_lwps and the process reaper will deal with it 599 * synchronously, which is much faster. 600 */ 601 if (masterexit == 0) { 602 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp); 603 --p->p_nthreads; 604 wakeup(&p->p_nthreads); 605 LIST_INSERT_HEAD(&deadlwp_list[mycpuid], lp, u.lwp_reap_entry); 606 taskqueue_enqueue(taskqueue_thread[mycpuid], deadlwp_task[mycpuid]); 607 } else { 608 --p->p_nthreads; 609 } 610 biosched_done(curthread); 611 cpu_lwp_exit(); 612 } 613 614 /* 615 * Wait until a lwp is completely dead. 616 * 617 * If the thread is still executing, which can't be waited upon, 618 * return failure. The caller is responsible of waiting a little 619 * bit and checking again. 620 * 621 * Suggested use: 622 * while (!lwp_wait(lp)) 623 * tsleep(lp, 0, "lwpwait", 1); 624 */ 625 static int 626 lwp_wait(struct lwp *lp) 627 { 628 struct thread *td = lp->lwp_thread;; 629 630 KKASSERT(lwkt_preempted_proc() != lp); 631 632 while (lp->lwp_lock > 0) 633 tsleep(lp, 0, "lwpwait1", 1); 634 635 lwkt_wait_free(td); 636 637 /* 638 * The lwp's thread may still be in the middle 639 * of switching away, we can't rip its stack out from 640 * under it until TDF_EXITING is set and both 641 * TDF_RUNNING and TDF_PREEMPT_LOCK are clear. 642 * TDF_PREEMPT_LOCK must be checked because TDF_RUNNING 643 * will be cleared temporarily if a thread gets 644 * preempted. 645 * 646 * YYY no wakeup occurs, so we simply return failure 647 * and let the caller deal with sleeping and calling 648 * us again. 649 */ 650 if ((td->td_flags & (TDF_RUNNING|TDF_PREEMPT_LOCK|TDF_EXITING)) != 651 TDF_EXITING) 652 return (0); 653 654 return (1); 655 } 656 657 /* 658 * Release the resources associated with a lwp. 659 * The lwp must be completely dead. 660 */ 661 void 662 lwp_dispose(struct lwp *lp) 663 { 664 struct thread *td = lp->lwp_thread;; 665 666 KKASSERT(lwkt_preempted_proc() != lp); 667 KKASSERT(td->td_refs == 0); 668 KKASSERT((td->td_flags & (TDF_RUNNING|TDF_PREEMPT_LOCK|TDF_EXITING)) == 669 TDF_EXITING); 670 671 PRELE(lp->lwp_proc); 672 lp->lwp_proc = NULL; 673 if (td != NULL) { 674 td->td_proc = NULL; 675 td->td_lwp = NULL; 676 lp->lwp_thread = NULL; 677 lwkt_free_thread(td); 678 } 679 kfree(lp, M_LWP); 680 } 681 682 /* 683 * MPSAFE 684 */ 685 int 686 sys_wait4(struct wait_args *uap) 687 { 688 struct rusage rusage; 689 int error, status; 690 691 error = kern_wait(uap->pid, (uap->status ? &status : NULL), 692 uap->options, (uap->rusage ? &rusage : NULL), 693 &uap->sysmsg_result); 694 695 if (error == 0 && uap->status) 696 error = copyout(&status, uap->status, sizeof(*uap->status)); 697 if (error == 0 && uap->rusage) 698 error = copyout(&rusage, uap->rusage, sizeof(*uap->rusage)); 699 return (error); 700 } 701 702 /* 703 * wait1() 704 * 705 * wait_args(int pid, int *status, int options, struct rusage *rusage) 706 * 707 * MPALMOSTSAFE 708 */ 709 int 710 kern_wait(pid_t pid, int *status, int options, struct rusage *rusage, int *res) 711 { 712 struct thread *td = curthread; 713 struct lwp *lp; 714 struct proc *q = td->td_proc; 715 struct proc *p, *t; 716 int nfound, error; 717 718 if (pid == 0) 719 pid = -q->p_pgid; 720 if (options &~ (WUNTRACED|WNOHANG|WCONTINUED|WLINUXCLONE)) 721 return (EINVAL); 722 get_mplock(); 723 loop: 724 /* 725 * Hack for backwards compatibility with badly written user code. 726 * Or perhaps we have to do this anyway, it is unclear. XXX 727 * 728 * The problem is that if a process group is stopped and the parent 729 * is doing a wait*(..., WUNTRACED, ...), it will see the STOP 730 * of the child and then stop itself when it tries to return from the 731 * system call. When the process group is resumed the parent will 732 * then get the STOP status even though the child has now resumed 733 * (a followup wait*() will get the CONT status). 734 * 735 * Previously the CONT would overwrite the STOP because the tstop 736 * was handled within tsleep(), and the parent would only see 737 * the CONT when both are stopped and continued together. This litte 738 * two-line hack restores this effect. 739 */ 740 while (q->p_stat == SSTOP) 741 tstop(); 742 743 nfound = 0; 744 LIST_FOREACH(p, &q->p_children, p_sibling) { 745 if (pid != WAIT_ANY && 746 p->p_pid != pid && p->p_pgid != -pid) 747 continue; 748 749 /* This special case handles a kthread spawned by linux_clone 750 * (see linux_misc.c). The linux_wait4 and linux_waitpid 751 * functions need to be able to distinguish between waiting 752 * on a process and waiting on a thread. It is a thread if 753 * p_sigparent is not SIGCHLD, and the WLINUXCLONE option 754 * signifies we want to wait for threads and not processes. 755 */ 756 if ((p->p_sigparent != SIGCHLD) ^ 757 ((options & WLINUXCLONE) != 0)) { 758 continue; 759 } 760 761 nfound++; 762 if (p->p_stat == SZOMB) { 763 /* 764 * We may go into SZOMB with threads still present. 765 * We must wait for them to exit before we can reap 766 * the master thread, otherwise we may race reaping 767 * non-master threads. 768 */ 769 while (p->p_nthreads > 0) { 770 tsleep(&p->p_nthreads, 0, "lwpzomb", hz); 771 } 772 773 /* 774 * Reap any LWPs left in p->p_lwps. This is usually 775 * just the last LWP. This must be done before 776 * we loop on p_lock since the lwps hold a ref on 777 * it as a vmspace interlock. 778 * 779 * Once that is accomplished p_nthreads had better 780 * be zero. 781 */ 782 while ((lp = RB_ROOT(&p->p_lwp_tree)) != NULL) { 783 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp); 784 reaplwp(lp); 785 } 786 KKASSERT(p->p_nthreads == 0); 787 788 /* 789 * Don't do anything really bad until all references 790 * to the process go away. This may include other 791 * LWPs which are still in the process of being 792 * reaped. We can't just pull the rug out from under 793 * them because they may still be using the VM space. 794 * 795 * Certain kernel facilities such as /proc will also 796 * put a hold on the process for short periods of 797 * time. 798 */ 799 while (p->p_lock) 800 tsleep(p, 0, "reap3", hz); 801 802 /* scheduling hook for heuristic */ 803 /* XXX no lwp available, we need a different heuristic */ 804 /* 805 p->p_usched->heuristic_exiting(td->td_lwp, deadlp); 806 */ 807 808 /* Take care of our return values. */ 809 *res = p->p_pid; 810 if (status) 811 *status = p->p_xstat; 812 if (rusage) 813 *rusage = p->p_ru; 814 /* 815 * If we got the child via a ptrace 'attach', 816 * we need to give it back to the old parent. 817 */ 818 if (p->p_oppid && (t = pfind(p->p_oppid))) { 819 p->p_oppid = 0; 820 proc_reparent(p, t); 821 ksignal(t, SIGCHLD); 822 wakeup((caddr_t)t); 823 error = 0; 824 goto done; 825 } 826 827 /* 828 * Unlink the proc from its process group so that 829 * the following operations won't lead to an 830 * inconsistent state for processes running down 831 * the zombie list. 832 */ 833 KKASSERT(p->p_lock == 0); 834 proc_remove_zombie(p); 835 leavepgrp(p); 836 837 p->p_xstat = 0; 838 ruadd(&q->p_cru, &p->p_ru); 839 840 /* 841 * Decrement the count of procs running with this uid. 842 */ 843 chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0); 844 845 /* 846 * Free up credentials. 847 */ 848 crfree(p->p_ucred); 849 p->p_ucred = NULL; 850 851 /* 852 * Remove unused arguments 853 */ 854 if (p->p_args && --p->p_args->ar_ref == 0) 855 FREE(p->p_args, M_PARGS); 856 857 if (--p->p_sigacts->ps_refcnt == 0) { 858 kfree(p->p_sigacts, M_SUBPROC); 859 p->p_sigacts = NULL; 860 } 861 862 vm_waitproc(p); 863 kfree(p, M_PROC); 864 nprocs--; 865 error = 0; 866 goto done; 867 } 868 if (p->p_stat == SSTOP && (p->p_flag & P_WAITED) == 0 && 869 (p->p_flag & P_TRACED || options & WUNTRACED)) { 870 p->p_flag |= P_WAITED; 871 872 *res = p->p_pid; 873 if (status) 874 *status = W_STOPCODE(p->p_xstat); 875 /* Zero rusage so we get something consistent. */ 876 if (rusage) 877 bzero(rusage, sizeof(rusage)); 878 error = 0; 879 goto done; 880 } 881 if (options & WCONTINUED && (p->p_flag & P_CONTINUED)) { 882 *res = p->p_pid; 883 p->p_flag &= ~P_CONTINUED; 884 885 if (status) 886 *status = SIGCONT; 887 error = 0; 888 goto done; 889 } 890 } 891 if (nfound == 0) { 892 error = ECHILD; 893 goto done; 894 } 895 if (options & WNOHANG) { 896 *res = 0; 897 error = 0; 898 goto done; 899 } 900 error = tsleep((caddr_t)q, PCATCH, "wait", 0); 901 if (error) { 902 done: 903 rel_mplock(); 904 return (error); 905 } 906 goto loop; 907 } 908 909 /* 910 * make process 'parent' the new parent of process 'child'. 911 */ 912 void 913 proc_reparent(struct proc *child, struct proc *parent) 914 { 915 916 if (child->p_pptr == parent) 917 return; 918 919 LIST_REMOVE(child, p_sibling); 920 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); 921 child->p_pptr = parent; 922 } 923 924 /* 925 * The next two functions are to handle adding/deleting items on the 926 * exit callout list 927 * 928 * at_exit(): 929 * Take the arguments given and put them onto the exit callout list, 930 * However first make sure that it's not already there. 931 * returns 0 on success. 932 */ 933 934 int 935 at_exit(exitlist_fn function) 936 { 937 struct exitlist *ep; 938 939 #ifdef INVARIANTS 940 /* Be noisy if the programmer has lost track of things */ 941 if (rm_at_exit(function)) 942 kprintf("WARNING: exit callout entry (%p) already present\n", 943 function); 944 #endif 945 ep = kmalloc(sizeof(*ep), M_ATEXIT, M_NOWAIT); 946 if (ep == NULL) 947 return (ENOMEM); 948 ep->function = function; 949 TAILQ_INSERT_TAIL(&exit_list, ep, next); 950 return (0); 951 } 952 953 /* 954 * Scan the exit callout list for the given item and remove it. 955 * Returns the number of items removed (0 or 1) 956 */ 957 int 958 rm_at_exit(exitlist_fn function) 959 { 960 struct exitlist *ep; 961 962 TAILQ_FOREACH(ep, &exit_list, next) { 963 if (ep->function == function) { 964 TAILQ_REMOVE(&exit_list, ep, next); 965 kfree(ep, M_ATEXIT); 966 return(1); 967 } 968 } 969 return (0); 970 } 971 972 /* 973 * LWP reaper related code. 974 */ 975 static void 976 reaplwps(void *context, int dummy) 977 { 978 struct lwplist *lwplist = context; 979 struct lwp *lp; 980 981 get_mplock(); 982 while ((lp = LIST_FIRST(lwplist))) { 983 LIST_REMOVE(lp, u.lwp_reap_entry); 984 reaplwp(lp); 985 } 986 rel_mplock(); 987 } 988 989 static void 990 reaplwp(struct lwp *lp) 991 { 992 while (lwp_wait(lp) == 0) 993 tsleep(lp, 0, "lwpreap", 1); 994 lwp_dispose(lp); 995 } 996 997 static void 998 deadlwp_init(void) 999 { 1000 int cpu; 1001 1002 for (cpu = 0; cpu < ncpus; cpu++) { 1003 LIST_INIT(&deadlwp_list[cpu]); 1004 deadlwp_task[cpu] = kmalloc(sizeof(*deadlwp_task[cpu]), M_DEVBUF, M_WAITOK); 1005 TASK_INIT(deadlwp_task[cpu], 0, reaplwps, &deadlwp_list[cpu]); 1006 } 1007 } 1008 1009 SYSINIT(deadlwpinit, SI_SUB_CONFIGURE, SI_ORDER_ANY, deadlwp_init, NULL); 1010