1 /* 2 * linux/kernel/exit.c 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 */ 6 7 #include <linux/config.h> 8 #include <linux/mm.h> 9 #include <linux/slab.h> 10 #include <linux/interrupt.h> 11 #include <linux/smp_lock.h> 12 #include <linux/module.h> 13 #include <linux/completion.h> 14 #include <linux/personality.h> 15 #include <linux/tty.h> 16 #include <linux/namespace.h> 17 #include <linux/key.h> 18 #include <linux/security.h> 19 #include <linux/cpu.h> 20 #include <linux/acct.h> 21 #include <linux/file.h> 22 #include <linux/binfmts.h> 23 #include <linux/ptrace.h> 24 #include <linux/profile.h> 25 #include <linux/mount.h> 26 #include <linux/proc_fs.h> 27 #include <linux/mempolicy.h> 28 #include <linux/cpuset.h> 29 #include <linux/syscalls.h> 30 #include <linux/signal.h> 31 32 #include <asm/uaccess.h> 33 #include <asm/unistd.h> 34 #include <asm/pgtable.h> 35 #include <asm/mmu_context.h> 36 37 extern void sem_exit (void); 38 extern struct task_struct *child_reaper; 39 40 int getrusage(struct task_struct *, int, struct rusage __user *); 41 42 static void exit_mm(struct task_struct * tsk); 43 44 static void __unhash_process(struct task_struct *p) 45 { 46 nr_threads--; 47 detach_pid(p, PIDTYPE_PID); 48 detach_pid(p, PIDTYPE_TGID); 49 if (thread_group_leader(p)) { 50 detach_pid(p, PIDTYPE_PGID); 51 detach_pid(p, PIDTYPE_SID); 52 if (p->pid) 53 __get_cpu_var(process_counts)--; 54 } 55 56 REMOVE_LINKS(p); 57 } 58 59 void release_task(struct task_struct * p) 60 { 61 int zap_leader; 62 task_t *leader; 63 struct dentry *proc_dentry; 64 65 repeat: 66 atomic_dec(&p->user->processes); 67 spin_lock(&p->proc_lock); 68 proc_dentry = proc_pid_unhash(p); 69 write_lock_irq(&tasklist_lock); 70 if (unlikely(p->ptrace)) 71 __ptrace_unlink(p); 72 BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children)); 73 __exit_signal(p); 74 __exit_sighand(p); 75 /* 76 * Note that the fastpath in sys_times depends on __exit_signal having 77 * updated the counters before a task is removed from the tasklist of 78 * the process by __unhash_process. 79 */ 80 __unhash_process(p); 81 82 /* 83 * If we are the last non-leader member of the thread 84 * group, and the leader is zombie, then notify the 85 * group leader's parent process. (if it wants notification.) 86 */ 87 zap_leader = 0; 88 leader = p->group_leader; 89 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) { 90 BUG_ON(leader->exit_signal == -1); 91 do_notify_parent(leader, leader->exit_signal); 92 /* 93 * If we were the last child thread and the leader has 94 * exited already, and the leader's parent ignores SIGCHLD, 95 * then we are the one who should release the leader. 96 * 97 * do_notify_parent() will have marked it self-reaping in 98 * that case. 99 */ 100 zap_leader = (leader->exit_signal == -1); 101 } 102 103 sched_exit(p); 104 write_unlock_irq(&tasklist_lock); 105 spin_unlock(&p->proc_lock); 106 proc_pid_flush(proc_dentry); 107 release_thread(p); 108 put_task_struct(p); 109 110 p = leader; 111 if (unlikely(zap_leader)) 112 goto repeat; 113 } 114 115 /* we are using it only for SMP init */ 116 117 void unhash_process(struct task_struct *p) 118 { 119 struct dentry *proc_dentry; 120 121 spin_lock(&p->proc_lock); 122 proc_dentry = proc_pid_unhash(p); 123 write_lock_irq(&tasklist_lock); 124 __unhash_process(p); 125 write_unlock_irq(&tasklist_lock); 126 spin_unlock(&p->proc_lock); 127 proc_pid_flush(proc_dentry); 128 } 129 130 /* 131 * This checks not only the pgrp, but falls back on the pid if no 132 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly 133 * without this... 134 */ 135 int session_of_pgrp(int pgrp) 136 { 137 struct task_struct *p; 138 int sid = -1; 139 140 read_lock(&tasklist_lock); 141 do_each_task_pid(pgrp, PIDTYPE_PGID, p) { 142 if (p->signal->session > 0) { 143 sid = p->signal->session; 144 goto out; 145 } 146 } while_each_task_pid(pgrp, PIDTYPE_PGID, p); 147 p = find_task_by_pid(pgrp); 148 if (p) 149 sid = p->signal->session; 150 out: 151 read_unlock(&tasklist_lock); 152 153 return sid; 154 } 155 156 /* 157 * Determine if a process group is "orphaned", according to the POSIX 158 * definition in 2.2.2.52. Orphaned process groups are not to be affected 159 * by terminal-generated stop signals. Newly orphaned process groups are 160 * to receive a SIGHUP and a SIGCONT. 161 * 162 * "I ask you, have you ever known what it is to be an orphan?" 163 */ 164 static int will_become_orphaned_pgrp(int pgrp, task_t *ignored_task) 165 { 166 struct task_struct *p; 167 int ret = 1; 168 169 do_each_task_pid(pgrp, PIDTYPE_PGID, p) { 170 if (p == ignored_task 171 || p->exit_state 172 || p->real_parent->pid == 1) 173 continue; 174 if (process_group(p->real_parent) != pgrp 175 && p->real_parent->signal->session == p->signal->session) { 176 ret = 0; 177 break; 178 } 179 } while_each_task_pid(pgrp, PIDTYPE_PGID, p); 180 return ret; /* (sighing) "Often!" */ 181 } 182 183 int is_orphaned_pgrp(int pgrp) 184 { 185 int retval; 186 187 read_lock(&tasklist_lock); 188 retval = will_become_orphaned_pgrp(pgrp, NULL); 189 read_unlock(&tasklist_lock); 190 191 return retval; 192 } 193 194 static inline int has_stopped_jobs(int pgrp) 195 { 196 int retval = 0; 197 struct task_struct *p; 198 199 do_each_task_pid(pgrp, PIDTYPE_PGID, p) { 200 if (p->state != TASK_STOPPED) 201 continue; 202 203 /* If p is stopped by a debugger on a signal that won't 204 stop it, then don't count p as stopped. This isn't 205 perfect but it's a good approximation. */ 206 if (unlikely (p->ptrace) 207 && p->exit_code != SIGSTOP 208 && p->exit_code != SIGTSTP 209 && p->exit_code != SIGTTOU 210 && p->exit_code != SIGTTIN) 211 continue; 212 213 retval = 1; 214 break; 215 } while_each_task_pid(pgrp, PIDTYPE_PGID, p); 216 return retval; 217 } 218 219 /** 220 * reparent_to_init - Reparent the calling kernel thread to the init task. 221 * 222 * If a kernel thread is launched as a result of a system call, or if 223 * it ever exits, it should generally reparent itself to init so that 224 * it is correctly cleaned up on exit. 225 * 226 * The various task state such as scheduling policy and priority may have 227 * been inherited from a user process, so we reset them to sane values here. 228 * 229 * NOTE that reparent_to_init() gives the caller full capabilities. 230 */ 231 static inline void reparent_to_init(void) 232 { 233 write_lock_irq(&tasklist_lock); 234 235 ptrace_unlink(current); 236 /* Reparent to init */ 237 REMOVE_LINKS(current); 238 current->parent = child_reaper; 239 current->real_parent = child_reaper; 240 SET_LINKS(current); 241 242 /* Set the exit signal to SIGCHLD so we signal init on exit */ 243 current->exit_signal = SIGCHLD; 244 245 if ((current->policy == SCHED_NORMAL) && (task_nice(current) < 0)) 246 set_user_nice(current, 0); 247 /* cpus_allowed? */ 248 /* rt_priority? */ 249 /* signals? */ 250 security_task_reparent_to_init(current); 251 memcpy(current->signal->rlim, init_task.signal->rlim, 252 sizeof(current->signal->rlim)); 253 atomic_inc(&(INIT_USER->__count)); 254 write_unlock_irq(&tasklist_lock); 255 switch_uid(INIT_USER); 256 } 257 258 void __set_special_pids(pid_t session, pid_t pgrp) 259 { 260 struct task_struct *curr = current; 261 262 if (curr->signal->session != session) { 263 detach_pid(curr, PIDTYPE_SID); 264 curr->signal->session = session; 265 attach_pid(curr, PIDTYPE_SID, session); 266 } 267 if (process_group(curr) != pgrp) { 268 detach_pid(curr, PIDTYPE_PGID); 269 curr->signal->pgrp = pgrp; 270 attach_pid(curr, PIDTYPE_PGID, pgrp); 271 } 272 } 273 274 void set_special_pids(pid_t session, pid_t pgrp) 275 { 276 write_lock_irq(&tasklist_lock); 277 __set_special_pids(session, pgrp); 278 write_unlock_irq(&tasklist_lock); 279 } 280 281 /* 282 * Let kernel threads use this to say that they 283 * allow a certain signal (since daemonize() will 284 * have disabled all of them by default). 285 */ 286 int allow_signal(int sig) 287 { 288 if (!valid_signal(sig) || sig < 1) 289 return -EINVAL; 290 291 spin_lock_irq(¤t->sighand->siglock); 292 sigdelset(¤t->blocked, sig); 293 if (!current->mm) { 294 /* Kernel threads handle their own signals. 295 Let the signal code know it'll be handled, so 296 that they don't get converted to SIGKILL or 297 just silently dropped */ 298 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2; 299 } 300 recalc_sigpending(); 301 spin_unlock_irq(¤t->sighand->siglock); 302 return 0; 303 } 304 305 EXPORT_SYMBOL(allow_signal); 306 307 int disallow_signal(int sig) 308 { 309 if (!valid_signal(sig) || sig < 1) 310 return -EINVAL; 311 312 spin_lock_irq(¤t->sighand->siglock); 313 sigaddset(¤t->blocked, sig); 314 recalc_sigpending(); 315 spin_unlock_irq(¤t->sighand->siglock); 316 return 0; 317 } 318 319 EXPORT_SYMBOL(disallow_signal); 320 321 /* 322 * Put all the gunge required to become a kernel thread without 323 * attached user resources in one place where it belongs. 324 */ 325 326 void daemonize(const char *name, ...) 327 { 328 va_list args; 329 struct fs_struct *fs; 330 sigset_t blocked; 331 332 va_start(args, name); 333 vsnprintf(current->comm, sizeof(current->comm), name, args); 334 va_end(args); 335 336 /* 337 * If we were started as result of loading a module, close all of the 338 * user space pages. We don't need them, and if we didn't close them 339 * they would be locked into memory. 340 */ 341 exit_mm(current); 342 343 set_special_pids(1, 1); 344 down(&tty_sem); 345 current->signal->tty = NULL; 346 up(&tty_sem); 347 348 /* Block and flush all signals */ 349 sigfillset(&blocked); 350 sigprocmask(SIG_BLOCK, &blocked, NULL); 351 flush_signals(current); 352 353 /* Become as one with the init task */ 354 355 exit_fs(current); /* current->fs->count--; */ 356 fs = init_task.fs; 357 current->fs = fs; 358 atomic_inc(&fs->count); 359 exit_files(current); 360 current->files = init_task.files; 361 atomic_inc(¤t->files->count); 362 363 reparent_to_init(); 364 } 365 366 EXPORT_SYMBOL(daemonize); 367 368 static inline void close_files(struct files_struct * files) 369 { 370 int i, j; 371 372 j = 0; 373 for (;;) { 374 unsigned long set; 375 i = j * __NFDBITS; 376 if (i >= files->max_fdset || i >= files->max_fds) 377 break; 378 set = files->open_fds->fds_bits[j++]; 379 while (set) { 380 if (set & 1) { 381 struct file * file = xchg(&files->fd[i], NULL); 382 if (file) 383 filp_close(file, files); 384 } 385 i++; 386 set >>= 1; 387 } 388 } 389 } 390 391 struct files_struct *get_files_struct(struct task_struct *task) 392 { 393 struct files_struct *files; 394 395 task_lock(task); 396 files = task->files; 397 if (files) 398 atomic_inc(&files->count); 399 task_unlock(task); 400 401 return files; 402 } 403 404 void fastcall put_files_struct(struct files_struct *files) 405 { 406 if (atomic_dec_and_test(&files->count)) { 407 close_files(files); 408 /* 409 * Free the fd and fdset arrays if we expanded them. 410 */ 411 if (files->fd != &files->fd_array[0]) 412 free_fd_array(files->fd, files->max_fds); 413 if (files->max_fdset > __FD_SETSIZE) { 414 free_fdset(files->open_fds, files->max_fdset); 415 free_fdset(files->close_on_exec, files->max_fdset); 416 } 417 kmem_cache_free(files_cachep, files); 418 } 419 } 420 421 EXPORT_SYMBOL(put_files_struct); 422 423 static inline void __exit_files(struct task_struct *tsk) 424 { 425 struct files_struct * files = tsk->files; 426 427 if (files) { 428 task_lock(tsk); 429 tsk->files = NULL; 430 task_unlock(tsk); 431 put_files_struct(files); 432 } 433 } 434 435 void exit_files(struct task_struct *tsk) 436 { 437 __exit_files(tsk); 438 } 439 440 static inline void __put_fs_struct(struct fs_struct *fs) 441 { 442 /* No need to hold fs->lock if we are killing it */ 443 if (atomic_dec_and_test(&fs->count)) { 444 dput(fs->root); 445 mntput(fs->rootmnt); 446 dput(fs->pwd); 447 mntput(fs->pwdmnt); 448 if (fs->altroot) { 449 dput(fs->altroot); 450 mntput(fs->altrootmnt); 451 } 452 kmem_cache_free(fs_cachep, fs); 453 } 454 } 455 456 void put_fs_struct(struct fs_struct *fs) 457 { 458 __put_fs_struct(fs); 459 } 460 461 static inline void __exit_fs(struct task_struct *tsk) 462 { 463 struct fs_struct * fs = tsk->fs; 464 465 if (fs) { 466 task_lock(tsk); 467 tsk->fs = NULL; 468 task_unlock(tsk); 469 __put_fs_struct(fs); 470 } 471 } 472 473 void exit_fs(struct task_struct *tsk) 474 { 475 __exit_fs(tsk); 476 } 477 478 EXPORT_SYMBOL_GPL(exit_fs); 479 480 /* 481 * Turn us into a lazy TLB process if we 482 * aren't already.. 483 */ 484 static void exit_mm(struct task_struct * tsk) 485 { 486 struct mm_struct *mm = tsk->mm; 487 488 mm_release(tsk, mm); 489 if (!mm) 490 return; 491 /* 492 * Serialize with any possible pending coredump. 493 * We must hold mmap_sem around checking core_waiters 494 * and clearing tsk->mm. The core-inducing thread 495 * will increment core_waiters for each thread in the 496 * group with ->mm != NULL. 497 */ 498 down_read(&mm->mmap_sem); 499 if (mm->core_waiters) { 500 up_read(&mm->mmap_sem); 501 down_write(&mm->mmap_sem); 502 if (!--mm->core_waiters) 503 complete(mm->core_startup_done); 504 up_write(&mm->mmap_sem); 505 506 wait_for_completion(&mm->core_done); 507 down_read(&mm->mmap_sem); 508 } 509 atomic_inc(&mm->mm_count); 510 if (mm != tsk->active_mm) BUG(); 511 /* more a memory barrier than a real lock */ 512 task_lock(tsk); 513 tsk->mm = NULL; 514 up_read(&mm->mmap_sem); 515 enter_lazy_tlb(mm, current); 516 task_unlock(tsk); 517 mmput(mm); 518 } 519 520 static inline void choose_new_parent(task_t *p, task_t *reaper, task_t *child_reaper) 521 { 522 /* 523 * Make sure we're not reparenting to ourselves and that 524 * the parent is not a zombie. 525 */ 526 BUG_ON(p == reaper || reaper->exit_state >= EXIT_ZOMBIE); 527 p->real_parent = reaper; 528 } 529 530 static inline void reparent_thread(task_t *p, task_t *father, int traced) 531 { 532 /* We don't want people slaying init. */ 533 if (p->exit_signal != -1) 534 p->exit_signal = SIGCHLD; 535 536 if (p->pdeath_signal) 537 /* We already hold the tasklist_lock here. */ 538 group_send_sig_info(p->pdeath_signal, (void *) 0, p); 539 540 /* Move the child from its dying parent to the new one. */ 541 if (unlikely(traced)) { 542 /* Preserve ptrace links if someone else is tracing this child. */ 543 list_del_init(&p->ptrace_list); 544 if (p->parent != p->real_parent) 545 list_add(&p->ptrace_list, &p->real_parent->ptrace_children); 546 } else { 547 /* If this child is being traced, then we're the one tracing it 548 * anyway, so let go of it. 549 */ 550 p->ptrace = 0; 551 list_del_init(&p->sibling); 552 p->parent = p->real_parent; 553 list_add_tail(&p->sibling, &p->parent->children); 554 555 /* If we'd notified the old parent about this child's death, 556 * also notify the new parent. 557 */ 558 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 && 559 thread_group_empty(p)) 560 do_notify_parent(p, p->exit_signal); 561 else if (p->state == TASK_TRACED) { 562 /* 563 * If it was at a trace stop, turn it into 564 * a normal stop since it's no longer being 565 * traced. 566 */ 567 ptrace_untrace(p); 568 } 569 } 570 571 /* 572 * process group orphan check 573 * Case ii: Our child is in a different pgrp 574 * than we are, and it was the only connection 575 * outside, so the child pgrp is now orphaned. 576 */ 577 if ((process_group(p) != process_group(father)) && 578 (p->signal->session == father->signal->session)) { 579 int pgrp = process_group(p); 580 581 if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) { 582 __kill_pg_info(SIGHUP, (void *)1, pgrp); 583 __kill_pg_info(SIGCONT, (void *)1, pgrp); 584 } 585 } 586 } 587 588 /* 589 * When we die, we re-parent all our children. 590 * Try to give them to another thread in our thread 591 * group, and if no such member exists, give it to 592 * the global child reaper process (ie "init") 593 */ 594 static inline void forget_original_parent(struct task_struct * father, 595 struct list_head *to_release) 596 { 597 struct task_struct *p, *reaper = father; 598 struct list_head *_p, *_n; 599 600 do { 601 reaper = next_thread(reaper); 602 if (reaper == father) { 603 reaper = child_reaper; 604 break; 605 } 606 } while (reaper->exit_state); 607 608 /* 609 * There are only two places where our children can be: 610 * 611 * - in our child list 612 * - in our ptraced child list 613 * 614 * Search them and reparent children. 615 */ 616 list_for_each_safe(_p, _n, &father->children) { 617 int ptrace; 618 p = list_entry(_p,struct task_struct,sibling); 619 620 ptrace = p->ptrace; 621 622 /* if father isn't the real parent, then ptrace must be enabled */ 623 BUG_ON(father != p->real_parent && !ptrace); 624 625 if (father == p->real_parent) { 626 /* reparent with a reaper, real father it's us */ 627 choose_new_parent(p, reaper, child_reaper); 628 reparent_thread(p, father, 0); 629 } else { 630 /* reparent ptraced task to its real parent */ 631 __ptrace_unlink (p); 632 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 && 633 thread_group_empty(p)) 634 do_notify_parent(p, p->exit_signal); 635 } 636 637 /* 638 * if the ptraced child is a zombie with exit_signal == -1 639 * we must collect it before we exit, or it will remain 640 * zombie forever since we prevented it from self-reap itself 641 * while it was being traced by us, to be able to see it in wait4. 642 */ 643 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1)) 644 list_add(&p->ptrace_list, to_release); 645 } 646 list_for_each_safe(_p, _n, &father->ptrace_children) { 647 p = list_entry(_p,struct task_struct,ptrace_list); 648 choose_new_parent(p, reaper, child_reaper); 649 reparent_thread(p, father, 1); 650 } 651 } 652 653 /* 654 * Send signals to all our closest relatives so that they know 655 * to properly mourn us.. 656 */ 657 static void exit_notify(struct task_struct *tsk) 658 { 659 int state; 660 struct task_struct *t; 661 struct list_head ptrace_dead, *_p, *_n; 662 663 if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT) 664 && !thread_group_empty(tsk)) { 665 /* 666 * This occurs when there was a race between our exit 667 * syscall and a group signal choosing us as the one to 668 * wake up. It could be that we are the only thread 669 * alerted to check for pending signals, but another thread 670 * should be woken now to take the signal since we will not. 671 * Now we'll wake all the threads in the group just to make 672 * sure someone gets all the pending signals. 673 */ 674 read_lock(&tasklist_lock); 675 spin_lock_irq(&tsk->sighand->siglock); 676 for (t = next_thread(tsk); t != tsk; t = next_thread(t)) 677 if (!signal_pending(t) && !(t->flags & PF_EXITING)) { 678 recalc_sigpending_tsk(t); 679 if (signal_pending(t)) 680 signal_wake_up(t, 0); 681 } 682 spin_unlock_irq(&tsk->sighand->siglock); 683 read_unlock(&tasklist_lock); 684 } 685 686 write_lock_irq(&tasklist_lock); 687 688 /* 689 * This does two things: 690 * 691 * A. Make init inherit all the child processes 692 * B. Check to see if any process groups have become orphaned 693 * as a result of our exiting, and if they have any stopped 694 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 695 */ 696 697 INIT_LIST_HEAD(&ptrace_dead); 698 forget_original_parent(tsk, &ptrace_dead); 699 BUG_ON(!list_empty(&tsk->children)); 700 BUG_ON(!list_empty(&tsk->ptrace_children)); 701 702 /* 703 * Check to see if any process groups have become orphaned 704 * as a result of our exiting, and if they have any stopped 705 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 706 * 707 * Case i: Our father is in a different pgrp than we are 708 * and we were the only connection outside, so our pgrp 709 * is about to become orphaned. 710 */ 711 712 t = tsk->real_parent; 713 714 if ((process_group(t) != process_group(tsk)) && 715 (t->signal->session == tsk->signal->session) && 716 will_become_orphaned_pgrp(process_group(tsk), tsk) && 717 has_stopped_jobs(process_group(tsk))) { 718 __kill_pg_info(SIGHUP, (void *)1, process_group(tsk)); 719 __kill_pg_info(SIGCONT, (void *)1, process_group(tsk)); 720 } 721 722 /* Let father know we died 723 * 724 * Thread signals are configurable, but you aren't going to use 725 * that to send signals to arbitary processes. 726 * That stops right now. 727 * 728 * If the parent exec id doesn't match the exec id we saved 729 * when we started then we know the parent has changed security 730 * domain. 731 * 732 * If our self_exec id doesn't match our parent_exec_id then 733 * we have changed execution domain as these two values started 734 * the same after a fork. 735 * 736 */ 737 738 if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 && 739 ( tsk->parent_exec_id != t->self_exec_id || 740 tsk->self_exec_id != tsk->parent_exec_id) 741 && !capable(CAP_KILL)) 742 tsk->exit_signal = SIGCHLD; 743 744 745 /* If something other than our normal parent is ptracing us, then 746 * send it a SIGCHLD instead of honoring exit_signal. exit_signal 747 * only has special meaning to our real parent. 748 */ 749 if (tsk->exit_signal != -1 && thread_group_empty(tsk)) { 750 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD; 751 do_notify_parent(tsk, signal); 752 } else if (tsk->ptrace) { 753 do_notify_parent(tsk, SIGCHLD); 754 } 755 756 state = EXIT_ZOMBIE; 757 if (tsk->exit_signal == -1 && 758 (likely(tsk->ptrace == 0) || 759 unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT))) 760 state = EXIT_DEAD; 761 tsk->exit_state = state; 762 763 write_unlock_irq(&tasklist_lock); 764 765 list_for_each_safe(_p, _n, &ptrace_dead) { 766 list_del_init(_p); 767 t = list_entry(_p,struct task_struct,ptrace_list); 768 release_task(t); 769 } 770 771 /* If the process is dead, release it - nobody will wait for it */ 772 if (state == EXIT_DEAD) 773 release_task(tsk); 774 775 /* PF_DEAD causes final put_task_struct after we schedule. */ 776 preempt_disable(); 777 tsk->flags |= PF_DEAD; 778 } 779 780 fastcall NORET_TYPE void do_exit(long code) 781 { 782 struct task_struct *tsk = current; 783 int group_dead; 784 785 profile_task_exit(tsk); 786 787 WARN_ON(atomic_read(&tsk->fs_excl)); 788 789 if (unlikely(in_interrupt())) 790 panic("Aiee, killing interrupt handler!"); 791 if (unlikely(!tsk->pid)) 792 panic("Attempted to kill the idle task!"); 793 if (unlikely(tsk->pid == 1)) 794 panic("Attempted to kill init!"); 795 if (tsk->io_context) 796 exit_io_context(); 797 798 if (unlikely(current->ptrace & PT_TRACE_EXIT)) { 799 current->ptrace_message = code; 800 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP); 801 } 802 803 /* 804 * We're taking recursive faults here in do_exit. Safest is to just 805 * leave this task alone and wait for reboot. 806 */ 807 if (unlikely(tsk->flags & PF_EXITING)) { 808 printk(KERN_ALERT 809 "Fixing recursive fault but reboot is needed!\n"); 810 set_current_state(TASK_UNINTERRUPTIBLE); 811 schedule(); 812 } 813 814 tsk->flags |= PF_EXITING; 815 816 /* 817 * Make sure we don't try to process any timer firings 818 * while we are already exiting. 819 */ 820 tsk->it_virt_expires = cputime_zero; 821 tsk->it_prof_expires = cputime_zero; 822 tsk->it_sched_expires = 0; 823 824 if (unlikely(in_atomic())) 825 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n", 826 current->comm, current->pid, 827 preempt_count()); 828 829 acct_update_integrals(tsk); 830 update_mem_hiwater(tsk); 831 group_dead = atomic_dec_and_test(&tsk->signal->live); 832 if (group_dead) { 833 del_timer_sync(&tsk->signal->real_timer); 834 acct_process(code); 835 } 836 exit_mm(tsk); 837 838 exit_sem(tsk); 839 __exit_files(tsk); 840 __exit_fs(tsk); 841 exit_namespace(tsk); 842 exit_thread(); 843 cpuset_exit(tsk); 844 exit_keys(tsk); 845 846 if (group_dead && tsk->signal->leader) 847 disassociate_ctty(1); 848 849 module_put(tsk->thread_info->exec_domain->module); 850 if (tsk->binfmt) 851 module_put(tsk->binfmt->module); 852 853 tsk->exit_code = code; 854 exit_notify(tsk); 855 #ifdef CONFIG_NUMA 856 mpol_free(tsk->mempolicy); 857 tsk->mempolicy = NULL; 858 #endif 859 860 BUG_ON(!(current->flags & PF_DEAD)); 861 schedule(); 862 BUG(); 863 /* Avoid "noreturn function does return". */ 864 for (;;) ; 865 } 866 867 EXPORT_SYMBOL_GPL(do_exit); 868 869 NORET_TYPE void complete_and_exit(struct completion *comp, long code) 870 { 871 if (comp) 872 complete(comp); 873 874 do_exit(code); 875 } 876 877 EXPORT_SYMBOL(complete_and_exit); 878 879 asmlinkage long sys_exit(int error_code) 880 { 881 do_exit((error_code&0xff)<<8); 882 } 883 884 task_t fastcall *next_thread(const task_t *p) 885 { 886 return pid_task(p->pids[PIDTYPE_TGID].pid_list.next, PIDTYPE_TGID); 887 } 888 889 EXPORT_SYMBOL(next_thread); 890 891 /* 892 * Take down every thread in the group. This is called by fatal signals 893 * as well as by sys_exit_group (below). 894 */ 895 NORET_TYPE void 896 do_group_exit(int exit_code) 897 { 898 BUG_ON(exit_code & 0x80); /* core dumps don't get here */ 899 900 if (current->signal->flags & SIGNAL_GROUP_EXIT) 901 exit_code = current->signal->group_exit_code; 902 else if (!thread_group_empty(current)) { 903 struct signal_struct *const sig = current->signal; 904 struct sighand_struct *const sighand = current->sighand; 905 read_lock(&tasklist_lock); 906 spin_lock_irq(&sighand->siglock); 907 if (sig->flags & SIGNAL_GROUP_EXIT) 908 /* Another thread got here before we took the lock. */ 909 exit_code = sig->group_exit_code; 910 else { 911 sig->flags = SIGNAL_GROUP_EXIT; 912 sig->group_exit_code = exit_code; 913 zap_other_threads(current); 914 } 915 spin_unlock_irq(&sighand->siglock); 916 read_unlock(&tasklist_lock); 917 } 918 919 do_exit(exit_code); 920 /* NOTREACHED */ 921 } 922 923 /* 924 * this kills every thread in the thread group. Note that any externally 925 * wait4()-ing process will get the correct exit code - even if this 926 * thread is not the thread group leader. 927 */ 928 asmlinkage void sys_exit_group(int error_code) 929 { 930 do_group_exit((error_code & 0xff) << 8); 931 } 932 933 static int eligible_child(pid_t pid, int options, task_t *p) 934 { 935 if (pid > 0) { 936 if (p->pid != pid) 937 return 0; 938 } else if (!pid) { 939 if (process_group(p) != process_group(current)) 940 return 0; 941 } else if (pid != -1) { 942 if (process_group(p) != -pid) 943 return 0; 944 } 945 946 /* 947 * Do not consider detached threads that are 948 * not ptraced: 949 */ 950 if (p->exit_signal == -1 && !p->ptrace) 951 return 0; 952 953 /* Wait for all children (clone and not) if __WALL is set; 954 * otherwise, wait for clone children *only* if __WCLONE is 955 * set; otherwise, wait for non-clone children *only*. (Note: 956 * A "clone" child here is one that reports to its parent 957 * using a signal other than SIGCHLD.) */ 958 if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0)) 959 && !(options & __WALL)) 960 return 0; 961 /* 962 * Do not consider thread group leaders that are 963 * in a non-empty thread group: 964 */ 965 if (current->tgid != p->tgid && delay_group_leader(p)) 966 return 2; 967 968 if (security_task_wait(p)) 969 return 0; 970 971 return 1; 972 } 973 974 static int wait_noreap_copyout(task_t *p, pid_t pid, uid_t uid, 975 int why, int status, 976 struct siginfo __user *infop, 977 struct rusage __user *rusagep) 978 { 979 int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0; 980 put_task_struct(p); 981 if (!retval) 982 retval = put_user(SIGCHLD, &infop->si_signo); 983 if (!retval) 984 retval = put_user(0, &infop->si_errno); 985 if (!retval) 986 retval = put_user((short)why, &infop->si_code); 987 if (!retval) 988 retval = put_user(pid, &infop->si_pid); 989 if (!retval) 990 retval = put_user(uid, &infop->si_uid); 991 if (!retval) 992 retval = put_user(status, &infop->si_status); 993 if (!retval) 994 retval = pid; 995 return retval; 996 } 997 998 /* 999 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold 1000 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1001 * the lock and this task is uninteresting. If we return nonzero, we have 1002 * released the lock and the system call should return. 1003 */ 1004 static int wait_task_zombie(task_t *p, int noreap, 1005 struct siginfo __user *infop, 1006 int __user *stat_addr, struct rusage __user *ru) 1007 { 1008 unsigned long state; 1009 int retval; 1010 int status; 1011 1012 if (unlikely(noreap)) { 1013 pid_t pid = p->pid; 1014 uid_t uid = p->uid; 1015 int exit_code = p->exit_code; 1016 int why, status; 1017 1018 if (unlikely(p->exit_state != EXIT_ZOMBIE)) 1019 return 0; 1020 if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) 1021 return 0; 1022 get_task_struct(p); 1023 read_unlock(&tasklist_lock); 1024 if ((exit_code & 0x7f) == 0) { 1025 why = CLD_EXITED; 1026 status = exit_code >> 8; 1027 } else { 1028 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED; 1029 status = exit_code & 0x7f; 1030 } 1031 return wait_noreap_copyout(p, pid, uid, why, 1032 status, infop, ru); 1033 } 1034 1035 /* 1036 * Try to move the task's state to DEAD 1037 * only one thread is allowed to do this: 1038 */ 1039 state = xchg(&p->exit_state, EXIT_DEAD); 1040 if (state != EXIT_ZOMBIE) { 1041 BUG_ON(state != EXIT_DEAD); 1042 return 0; 1043 } 1044 if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) { 1045 /* 1046 * This can only happen in a race with a ptraced thread 1047 * dying on another processor. 1048 */ 1049 return 0; 1050 } 1051 1052 if (likely(p->real_parent == p->parent) && likely(p->signal)) { 1053 /* 1054 * The resource counters for the group leader are in its 1055 * own task_struct. Those for dead threads in the group 1056 * are in its signal_struct, as are those for the child 1057 * processes it has previously reaped. All these 1058 * accumulate in the parent's signal_struct c* fields. 1059 * 1060 * We don't bother to take a lock here to protect these 1061 * p->signal fields, because they are only touched by 1062 * __exit_signal, which runs with tasklist_lock 1063 * write-locked anyway, and so is excluded here. We do 1064 * need to protect the access to p->parent->signal fields, 1065 * as other threads in the parent group can be right 1066 * here reaping other children at the same time. 1067 */ 1068 spin_lock_irq(&p->parent->sighand->siglock); 1069 p->parent->signal->cutime = 1070 cputime_add(p->parent->signal->cutime, 1071 cputime_add(p->utime, 1072 cputime_add(p->signal->utime, 1073 p->signal->cutime))); 1074 p->parent->signal->cstime = 1075 cputime_add(p->parent->signal->cstime, 1076 cputime_add(p->stime, 1077 cputime_add(p->signal->stime, 1078 p->signal->cstime))); 1079 p->parent->signal->cmin_flt += 1080 p->min_flt + p->signal->min_flt + p->signal->cmin_flt; 1081 p->parent->signal->cmaj_flt += 1082 p->maj_flt + p->signal->maj_flt + p->signal->cmaj_flt; 1083 p->parent->signal->cnvcsw += 1084 p->nvcsw + p->signal->nvcsw + p->signal->cnvcsw; 1085 p->parent->signal->cnivcsw += 1086 p->nivcsw + p->signal->nivcsw + p->signal->cnivcsw; 1087 spin_unlock_irq(&p->parent->sighand->siglock); 1088 } 1089 1090 /* 1091 * Now we are sure this task is interesting, and no other 1092 * thread can reap it because we set its state to EXIT_DEAD. 1093 */ 1094 read_unlock(&tasklist_lock); 1095 1096 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; 1097 status = (p->signal->flags & SIGNAL_GROUP_EXIT) 1098 ? p->signal->group_exit_code : p->exit_code; 1099 if (!retval && stat_addr) 1100 retval = put_user(status, stat_addr); 1101 if (!retval && infop) 1102 retval = put_user(SIGCHLD, &infop->si_signo); 1103 if (!retval && infop) 1104 retval = put_user(0, &infop->si_errno); 1105 if (!retval && infop) { 1106 int why; 1107 1108 if ((status & 0x7f) == 0) { 1109 why = CLD_EXITED; 1110 status >>= 8; 1111 } else { 1112 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; 1113 status &= 0x7f; 1114 } 1115 retval = put_user((short)why, &infop->si_code); 1116 if (!retval) 1117 retval = put_user(status, &infop->si_status); 1118 } 1119 if (!retval && infop) 1120 retval = put_user(p->pid, &infop->si_pid); 1121 if (!retval && infop) 1122 retval = put_user(p->uid, &infop->si_uid); 1123 if (retval) { 1124 // TODO: is this safe? 1125 p->exit_state = EXIT_ZOMBIE; 1126 return retval; 1127 } 1128 retval = p->pid; 1129 if (p->real_parent != p->parent) { 1130 write_lock_irq(&tasklist_lock); 1131 /* Double-check with lock held. */ 1132 if (p->real_parent != p->parent) { 1133 __ptrace_unlink(p); 1134 // TODO: is this safe? 1135 p->exit_state = EXIT_ZOMBIE; 1136 /* 1137 * If this is not a detached task, notify the parent. 1138 * If it's still not detached after that, don't release 1139 * it now. 1140 */ 1141 if (p->exit_signal != -1) { 1142 do_notify_parent(p, p->exit_signal); 1143 if (p->exit_signal != -1) 1144 p = NULL; 1145 } 1146 } 1147 write_unlock_irq(&tasklist_lock); 1148 } 1149 if (p != NULL) 1150 release_task(p); 1151 BUG_ON(!retval); 1152 return retval; 1153 } 1154 1155 /* 1156 * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold 1157 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1158 * the lock and this task is uninteresting. If we return nonzero, we have 1159 * released the lock and the system call should return. 1160 */ 1161 static int wait_task_stopped(task_t *p, int delayed_group_leader, int noreap, 1162 struct siginfo __user *infop, 1163 int __user *stat_addr, struct rusage __user *ru) 1164 { 1165 int retval, exit_code; 1166 1167 if (!p->exit_code) 1168 return 0; 1169 if (delayed_group_leader && !(p->ptrace & PT_PTRACED) && 1170 p->signal && p->signal->group_stop_count > 0) 1171 /* 1172 * A group stop is in progress and this is the group leader. 1173 * We won't report until all threads have stopped. 1174 */ 1175 return 0; 1176 1177 /* 1178 * Now we are pretty sure this task is interesting. 1179 * Make sure it doesn't get reaped out from under us while we 1180 * give up the lock and then examine it below. We don't want to 1181 * keep holding onto the tasklist_lock while we call getrusage and 1182 * possibly take page faults for user memory. 1183 */ 1184 get_task_struct(p); 1185 read_unlock(&tasklist_lock); 1186 1187 if (unlikely(noreap)) { 1188 pid_t pid = p->pid; 1189 uid_t uid = p->uid; 1190 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED; 1191 1192 exit_code = p->exit_code; 1193 if (unlikely(!exit_code) || 1194 unlikely(p->state > TASK_STOPPED)) 1195 goto bail_ref; 1196 return wait_noreap_copyout(p, pid, uid, 1197 why, (exit_code << 8) | 0x7f, 1198 infop, ru); 1199 } 1200 1201 write_lock_irq(&tasklist_lock); 1202 1203 /* 1204 * This uses xchg to be atomic with the thread resuming and setting 1205 * it. It must also be done with the write lock held to prevent a 1206 * race with the EXIT_ZOMBIE case. 1207 */ 1208 exit_code = xchg(&p->exit_code, 0); 1209 if (unlikely(p->exit_state)) { 1210 /* 1211 * The task resumed and then died. Let the next iteration 1212 * catch it in EXIT_ZOMBIE. Note that exit_code might 1213 * already be zero here if it resumed and did _exit(0). 1214 * The task itself is dead and won't touch exit_code again; 1215 * other processors in this function are locked out. 1216 */ 1217 p->exit_code = exit_code; 1218 exit_code = 0; 1219 } 1220 if (unlikely(exit_code == 0)) { 1221 /* 1222 * Another thread in this function got to it first, or it 1223 * resumed, or it resumed and then died. 1224 */ 1225 write_unlock_irq(&tasklist_lock); 1226 bail_ref: 1227 put_task_struct(p); 1228 /* 1229 * We are returning to the wait loop without having successfully 1230 * removed the process and having released the lock. We cannot 1231 * continue, since the "p" task pointer is potentially stale. 1232 * 1233 * Return -EAGAIN, and do_wait() will restart the loop from the 1234 * beginning. Do _not_ re-acquire the lock. 1235 */ 1236 return -EAGAIN; 1237 } 1238 1239 /* move to end of parent's list to avoid starvation */ 1240 remove_parent(p); 1241 add_parent(p, p->parent); 1242 1243 write_unlock_irq(&tasklist_lock); 1244 1245 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; 1246 if (!retval && stat_addr) 1247 retval = put_user((exit_code << 8) | 0x7f, stat_addr); 1248 if (!retval && infop) 1249 retval = put_user(SIGCHLD, &infop->si_signo); 1250 if (!retval && infop) 1251 retval = put_user(0, &infop->si_errno); 1252 if (!retval && infop) 1253 retval = put_user((short)((p->ptrace & PT_PTRACED) 1254 ? CLD_TRAPPED : CLD_STOPPED), 1255 &infop->si_code); 1256 if (!retval && infop) 1257 retval = put_user(exit_code, &infop->si_status); 1258 if (!retval && infop) 1259 retval = put_user(p->pid, &infop->si_pid); 1260 if (!retval && infop) 1261 retval = put_user(p->uid, &infop->si_uid); 1262 if (!retval) 1263 retval = p->pid; 1264 put_task_struct(p); 1265 1266 BUG_ON(!retval); 1267 return retval; 1268 } 1269 1270 /* 1271 * Handle do_wait work for one task in a live, non-stopped state. 1272 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1273 * the lock and this task is uninteresting. If we return nonzero, we have 1274 * released the lock and the system call should return. 1275 */ 1276 static int wait_task_continued(task_t *p, int noreap, 1277 struct siginfo __user *infop, 1278 int __user *stat_addr, struct rusage __user *ru) 1279 { 1280 int retval; 1281 pid_t pid; 1282 uid_t uid; 1283 1284 if (unlikely(!p->signal)) 1285 return 0; 1286 1287 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) 1288 return 0; 1289 1290 spin_lock_irq(&p->sighand->siglock); 1291 /* Re-check with the lock held. */ 1292 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { 1293 spin_unlock_irq(&p->sighand->siglock); 1294 return 0; 1295 } 1296 if (!noreap) 1297 p->signal->flags &= ~SIGNAL_STOP_CONTINUED; 1298 spin_unlock_irq(&p->sighand->siglock); 1299 1300 pid = p->pid; 1301 uid = p->uid; 1302 get_task_struct(p); 1303 read_unlock(&tasklist_lock); 1304 1305 if (!infop) { 1306 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; 1307 put_task_struct(p); 1308 if (!retval && stat_addr) 1309 retval = put_user(0xffff, stat_addr); 1310 if (!retval) 1311 retval = p->pid; 1312 } else { 1313 retval = wait_noreap_copyout(p, pid, uid, 1314 CLD_CONTINUED, SIGCONT, 1315 infop, ru); 1316 BUG_ON(retval == 0); 1317 } 1318 1319 return retval; 1320 } 1321 1322 1323 static inline int my_ptrace_child(struct task_struct *p) 1324 { 1325 if (!(p->ptrace & PT_PTRACED)) 1326 return 0; 1327 if (!(p->ptrace & PT_ATTACHED)) 1328 return 1; 1329 /* 1330 * This child was PTRACE_ATTACH'd. We should be seeing it only if 1331 * we are the attacher. If we are the real parent, this is a race 1332 * inside ptrace_attach. It is waiting for the tasklist_lock, 1333 * which we have to switch the parent links, but has already set 1334 * the flags in p->ptrace. 1335 */ 1336 return (p->parent != p->real_parent); 1337 } 1338 1339 static long do_wait(pid_t pid, int options, struct siginfo __user *infop, 1340 int __user *stat_addr, struct rusage __user *ru) 1341 { 1342 DECLARE_WAITQUEUE(wait, current); 1343 struct task_struct *tsk; 1344 int flag, retval; 1345 1346 add_wait_queue(¤t->signal->wait_chldexit,&wait); 1347 repeat: 1348 /* 1349 * We will set this flag if we see any child that might later 1350 * match our criteria, even if we are not able to reap it yet. 1351 */ 1352 flag = 0; 1353 current->state = TASK_INTERRUPTIBLE; 1354 read_lock(&tasklist_lock); 1355 tsk = current; 1356 do { 1357 struct task_struct *p; 1358 struct list_head *_p; 1359 int ret; 1360 1361 list_for_each(_p,&tsk->children) { 1362 p = list_entry(_p,struct task_struct,sibling); 1363 1364 ret = eligible_child(pid, options, p); 1365 if (!ret) 1366 continue; 1367 1368 switch (p->state) { 1369 case TASK_TRACED: 1370 if (!my_ptrace_child(p)) 1371 continue; 1372 /*FALLTHROUGH*/ 1373 case TASK_STOPPED: 1374 /* 1375 * It's stopped now, so it might later 1376 * continue, exit, or stop again. 1377 */ 1378 flag = 1; 1379 if (!(options & WUNTRACED) && 1380 !my_ptrace_child(p)) 1381 continue; 1382 retval = wait_task_stopped(p, ret == 2, 1383 (options & WNOWAIT), 1384 infop, 1385 stat_addr, ru); 1386 if (retval == -EAGAIN) 1387 goto repeat; 1388 if (retval != 0) /* He released the lock. */ 1389 goto end; 1390 break; 1391 default: 1392 // case EXIT_DEAD: 1393 if (p->exit_state == EXIT_DEAD) 1394 continue; 1395 // case EXIT_ZOMBIE: 1396 if (p->exit_state == EXIT_ZOMBIE) { 1397 /* 1398 * Eligible but we cannot release 1399 * it yet: 1400 */ 1401 if (ret == 2) 1402 goto check_continued; 1403 if (!likely(options & WEXITED)) 1404 continue; 1405 retval = wait_task_zombie( 1406 p, (options & WNOWAIT), 1407 infop, stat_addr, ru); 1408 /* He released the lock. */ 1409 if (retval != 0) 1410 goto end; 1411 break; 1412 } 1413 check_continued: 1414 /* 1415 * It's running now, so it might later 1416 * exit, stop, or stop and then continue. 1417 */ 1418 flag = 1; 1419 if (!unlikely(options & WCONTINUED)) 1420 continue; 1421 retval = wait_task_continued( 1422 p, (options & WNOWAIT), 1423 infop, stat_addr, ru); 1424 if (retval != 0) /* He released the lock. */ 1425 goto end; 1426 break; 1427 } 1428 } 1429 if (!flag) { 1430 list_for_each(_p, &tsk->ptrace_children) { 1431 p = list_entry(_p, struct task_struct, 1432 ptrace_list); 1433 if (!eligible_child(pid, options, p)) 1434 continue; 1435 flag = 1; 1436 break; 1437 } 1438 } 1439 if (options & __WNOTHREAD) 1440 break; 1441 tsk = next_thread(tsk); 1442 if (tsk->signal != current->signal) 1443 BUG(); 1444 } while (tsk != current); 1445 1446 read_unlock(&tasklist_lock); 1447 if (flag) { 1448 retval = 0; 1449 if (options & WNOHANG) 1450 goto end; 1451 retval = -ERESTARTSYS; 1452 if (signal_pending(current)) 1453 goto end; 1454 schedule(); 1455 goto repeat; 1456 } 1457 retval = -ECHILD; 1458 end: 1459 current->state = TASK_RUNNING; 1460 remove_wait_queue(¤t->signal->wait_chldexit,&wait); 1461 if (infop) { 1462 if (retval > 0) 1463 retval = 0; 1464 else { 1465 /* 1466 * For a WNOHANG return, clear out all the fields 1467 * we would set so the user can easily tell the 1468 * difference. 1469 */ 1470 if (!retval) 1471 retval = put_user(0, &infop->si_signo); 1472 if (!retval) 1473 retval = put_user(0, &infop->si_errno); 1474 if (!retval) 1475 retval = put_user(0, &infop->si_code); 1476 if (!retval) 1477 retval = put_user(0, &infop->si_pid); 1478 if (!retval) 1479 retval = put_user(0, &infop->si_uid); 1480 if (!retval) 1481 retval = put_user(0, &infop->si_status); 1482 } 1483 } 1484 return retval; 1485 } 1486 1487 asmlinkage long sys_waitid(int which, pid_t pid, 1488 struct siginfo __user *infop, int options, 1489 struct rusage __user *ru) 1490 { 1491 long ret; 1492 1493 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED)) 1494 return -EINVAL; 1495 if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) 1496 return -EINVAL; 1497 1498 switch (which) { 1499 case P_ALL: 1500 pid = -1; 1501 break; 1502 case P_PID: 1503 if (pid <= 0) 1504 return -EINVAL; 1505 break; 1506 case P_PGID: 1507 if (pid <= 0) 1508 return -EINVAL; 1509 pid = -pid; 1510 break; 1511 default: 1512 return -EINVAL; 1513 } 1514 1515 ret = do_wait(pid, options, infop, NULL, ru); 1516 1517 /* avoid REGPARM breakage on x86: */ 1518 prevent_tail_call(ret); 1519 return ret; 1520 } 1521 1522 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr, 1523 int options, struct rusage __user *ru) 1524 { 1525 long ret; 1526 1527 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| 1528 __WNOTHREAD|__WCLONE|__WALL)) 1529 return -EINVAL; 1530 ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru); 1531 1532 /* avoid REGPARM breakage on x86: */ 1533 prevent_tail_call(ret); 1534 return ret; 1535 } 1536 1537 #ifdef __ARCH_WANT_SYS_WAITPID 1538 1539 /* 1540 * sys_waitpid() remains for compatibility. waitpid() should be 1541 * implemented by calling sys_wait4() from libc.a. 1542 */ 1543 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options) 1544 { 1545 return sys_wait4(pid, stat_addr, options, NULL); 1546 } 1547 1548 #endif 1549