1 /* 2 * linux/kernel/exit.c 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 */ 6 7 #include <linux/mm.h> 8 #include <linux/slab.h> 9 #include <linux/interrupt.h> 10 #include <linux/module.h> 11 #include <linux/capability.h> 12 #include <linux/completion.h> 13 #include <linux/personality.h> 14 #include <linux/tty.h> 15 #include <linux/mnt_namespace.h> 16 #include <linux/key.h> 17 #include <linux/security.h> 18 #include <linux/cpu.h> 19 #include <linux/acct.h> 20 #include <linux/tsacct_kern.h> 21 #include <linux/file.h> 22 #include <linux/fdtable.h> 23 #include <linux/binfmts.h> 24 #include <linux/nsproxy.h> 25 #include <linux/pid_namespace.h> 26 #include <linux/ptrace.h> 27 #include <linux/profile.h> 28 #include <linux/mount.h> 29 #include <linux/proc_fs.h> 30 #include <linux/kthread.h> 31 #include <linux/mempolicy.h> 32 #include <linux/taskstats_kern.h> 33 #include <linux/delayacct.h> 34 #include <linux/freezer.h> 35 #include <linux/cgroup.h> 36 #include <linux/syscalls.h> 37 #include <linux/signal.h> 38 #include <linux/posix-timers.h> 39 #include <linux/cn_proc.h> 40 #include <linux/mutex.h> 41 #include <linux/futex.h> 42 #include <linux/compat.h> 43 #include <linux/pipe_fs_i.h> 44 #include <linux/audit.h> /* for audit_free() */ 45 #include <linux/resource.h> 46 #include <linux/blkdev.h> 47 #include <linux/task_io_accounting_ops.h> 48 49 #include <asm/uaccess.h> 50 #include <asm/unistd.h> 51 #include <asm/pgtable.h> 52 #include <asm/mmu_context.h> 53 54 static void exit_mm(struct task_struct * tsk); 55 56 static inline int task_detached(struct task_struct *p) 57 { 58 return p->exit_signal == -1; 59 } 60 61 static void __unhash_process(struct task_struct *p) 62 { 63 nr_threads--; 64 detach_pid(p, PIDTYPE_PID); 65 if (thread_group_leader(p)) { 66 detach_pid(p, PIDTYPE_PGID); 67 detach_pid(p, PIDTYPE_SID); 68 69 list_del_rcu(&p->tasks); 70 __get_cpu_var(process_counts)--; 71 } 72 list_del_rcu(&p->thread_group); 73 remove_parent(p); 74 } 75 76 /* 77 * This function expects the tasklist_lock write-locked. 78 */ 79 static void __exit_signal(struct task_struct *tsk) 80 { 81 struct signal_struct *sig = tsk->signal; 82 struct sighand_struct *sighand; 83 84 BUG_ON(!sig); 85 BUG_ON(!atomic_read(&sig->count)); 86 87 rcu_read_lock(); 88 sighand = rcu_dereference(tsk->sighand); 89 spin_lock(&sighand->siglock); 90 91 posix_cpu_timers_exit(tsk); 92 if (atomic_dec_and_test(&sig->count)) 93 posix_cpu_timers_exit_group(tsk); 94 else { 95 /* 96 * If there is any task waiting for the group exit 97 * then notify it: 98 */ 99 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) 100 wake_up_process(sig->group_exit_task); 101 102 if (tsk == sig->curr_target) 103 sig->curr_target = next_thread(tsk); 104 /* 105 * Accumulate here the counters for all threads but the 106 * group leader as they die, so they can be added into 107 * the process-wide totals when those are taken. 108 * The group leader stays around as a zombie as long 109 * as there are other threads. When it gets reaped, 110 * the exit.c code will add its counts into these totals. 111 * We won't ever get here for the group leader, since it 112 * will have been the last reference on the signal_struct. 113 */ 114 sig->utime = cputime_add(sig->utime, tsk->utime); 115 sig->stime = cputime_add(sig->stime, tsk->stime); 116 sig->gtime = cputime_add(sig->gtime, tsk->gtime); 117 sig->min_flt += tsk->min_flt; 118 sig->maj_flt += tsk->maj_flt; 119 sig->nvcsw += tsk->nvcsw; 120 sig->nivcsw += tsk->nivcsw; 121 sig->inblock += task_io_get_inblock(tsk); 122 sig->oublock += task_io_get_oublock(tsk); 123 sig->sum_sched_runtime += tsk->se.sum_exec_runtime; 124 sig = NULL; /* Marker for below. */ 125 } 126 127 __unhash_process(tsk); 128 129 tsk->signal = NULL; 130 tsk->sighand = NULL; 131 spin_unlock(&sighand->siglock); 132 rcu_read_unlock(); 133 134 __cleanup_sighand(sighand); 135 clear_tsk_thread_flag(tsk,TIF_SIGPENDING); 136 flush_sigqueue(&tsk->pending); 137 if (sig) { 138 flush_sigqueue(&sig->shared_pending); 139 taskstats_tgid_free(sig); 140 __cleanup_signal(sig); 141 } 142 } 143 144 static void delayed_put_task_struct(struct rcu_head *rhp) 145 { 146 put_task_struct(container_of(rhp, struct task_struct, rcu)); 147 } 148 149 void release_task(struct task_struct * p) 150 { 151 struct task_struct *leader; 152 int zap_leader; 153 repeat: 154 atomic_dec(&p->user->processes); 155 proc_flush_task(p); 156 write_lock_irq(&tasklist_lock); 157 ptrace_unlink(p); 158 BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children)); 159 __exit_signal(p); 160 161 /* 162 * If we are the last non-leader member of the thread 163 * group, and the leader is zombie, then notify the 164 * group leader's parent process. (if it wants notification.) 165 */ 166 zap_leader = 0; 167 leader = p->group_leader; 168 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) { 169 BUG_ON(task_detached(leader)); 170 do_notify_parent(leader, leader->exit_signal); 171 /* 172 * If we were the last child thread and the leader has 173 * exited already, and the leader's parent ignores SIGCHLD, 174 * then we are the one who should release the leader. 175 * 176 * do_notify_parent() will have marked it self-reaping in 177 * that case. 178 */ 179 zap_leader = task_detached(leader); 180 } 181 182 write_unlock_irq(&tasklist_lock); 183 release_thread(p); 184 call_rcu(&p->rcu, delayed_put_task_struct); 185 186 p = leader; 187 if (unlikely(zap_leader)) 188 goto repeat; 189 } 190 191 /* 192 * This checks not only the pgrp, but falls back on the pid if no 193 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly 194 * without this... 195 * 196 * The caller must hold rcu lock or the tasklist lock. 197 */ 198 struct pid *session_of_pgrp(struct pid *pgrp) 199 { 200 struct task_struct *p; 201 struct pid *sid = NULL; 202 203 p = pid_task(pgrp, PIDTYPE_PGID); 204 if (p == NULL) 205 p = pid_task(pgrp, PIDTYPE_PID); 206 if (p != NULL) 207 sid = task_session(p); 208 209 return sid; 210 } 211 212 /* 213 * Determine if a process group is "orphaned", according to the POSIX 214 * definition in 2.2.2.52. Orphaned process groups are not to be affected 215 * by terminal-generated stop signals. Newly orphaned process groups are 216 * to receive a SIGHUP and a SIGCONT. 217 * 218 * "I ask you, have you ever known what it is to be an orphan?" 219 */ 220 static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task) 221 { 222 struct task_struct *p; 223 224 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 225 if ((p == ignored_task) || 226 (p->exit_state && thread_group_empty(p)) || 227 is_global_init(p->real_parent)) 228 continue; 229 230 if (task_pgrp(p->real_parent) != pgrp && 231 task_session(p->real_parent) == task_session(p)) 232 return 0; 233 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 234 235 return 1; 236 } 237 238 int is_current_pgrp_orphaned(void) 239 { 240 int retval; 241 242 read_lock(&tasklist_lock); 243 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); 244 read_unlock(&tasklist_lock); 245 246 return retval; 247 } 248 249 static int has_stopped_jobs(struct pid *pgrp) 250 { 251 int retval = 0; 252 struct task_struct *p; 253 254 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 255 if (!task_is_stopped(p)) 256 continue; 257 retval = 1; 258 break; 259 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 260 return retval; 261 } 262 263 /* 264 * Check to see if any process groups have become orphaned as 265 * a result of our exiting, and if they have any stopped jobs, 266 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 267 */ 268 static void 269 kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) 270 { 271 struct pid *pgrp = task_pgrp(tsk); 272 struct task_struct *ignored_task = tsk; 273 274 if (!parent) 275 /* exit: our father is in a different pgrp than 276 * we are and we were the only connection outside. 277 */ 278 parent = tsk->real_parent; 279 else 280 /* reparent: our child is in a different pgrp than 281 * we are, and it was the only connection outside. 282 */ 283 ignored_task = NULL; 284 285 if (task_pgrp(parent) != pgrp && 286 task_session(parent) == task_session(tsk) && 287 will_become_orphaned_pgrp(pgrp, ignored_task) && 288 has_stopped_jobs(pgrp)) { 289 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); 290 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); 291 } 292 } 293 294 /** 295 * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd 296 * 297 * If a kernel thread is launched as a result of a system call, or if 298 * it ever exits, it should generally reparent itself to kthreadd so it 299 * isn't in the way of other processes and is correctly cleaned up on exit. 300 * 301 * The various task state such as scheduling policy and priority may have 302 * been inherited from a user process, so we reset them to sane values here. 303 * 304 * NOTE that reparent_to_kthreadd() gives the caller full capabilities. 305 */ 306 static void reparent_to_kthreadd(void) 307 { 308 write_lock_irq(&tasklist_lock); 309 310 ptrace_unlink(current); 311 /* Reparent to init */ 312 remove_parent(current); 313 current->real_parent = current->parent = kthreadd_task; 314 add_parent(current); 315 316 /* Set the exit signal to SIGCHLD so we signal init on exit */ 317 current->exit_signal = SIGCHLD; 318 319 if (task_nice(current) < 0) 320 set_user_nice(current, 0); 321 /* cpus_allowed? */ 322 /* rt_priority? */ 323 /* signals? */ 324 security_task_reparent_to_init(current); 325 memcpy(current->signal->rlim, init_task.signal->rlim, 326 sizeof(current->signal->rlim)); 327 atomic_inc(&(INIT_USER->__count)); 328 write_unlock_irq(&tasklist_lock); 329 switch_uid(INIT_USER); 330 } 331 332 void __set_special_pids(struct pid *pid) 333 { 334 struct task_struct *curr = current->group_leader; 335 pid_t nr = pid_nr(pid); 336 337 if (task_session(curr) != pid) { 338 change_pid(curr, PIDTYPE_SID, pid); 339 set_task_session(curr, nr); 340 } 341 if (task_pgrp(curr) != pid) { 342 change_pid(curr, PIDTYPE_PGID, pid); 343 set_task_pgrp(curr, nr); 344 } 345 } 346 347 static void set_special_pids(struct pid *pid) 348 { 349 write_lock_irq(&tasklist_lock); 350 __set_special_pids(pid); 351 write_unlock_irq(&tasklist_lock); 352 } 353 354 /* 355 * Let kernel threads use this to say that they 356 * allow a certain signal (since daemonize() will 357 * have disabled all of them by default). 358 */ 359 int allow_signal(int sig) 360 { 361 if (!valid_signal(sig) || sig < 1) 362 return -EINVAL; 363 364 spin_lock_irq(¤t->sighand->siglock); 365 sigdelset(¤t->blocked, sig); 366 if (!current->mm) { 367 /* Kernel threads handle their own signals. 368 Let the signal code know it'll be handled, so 369 that they don't get converted to SIGKILL or 370 just silently dropped */ 371 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2; 372 } 373 recalc_sigpending(); 374 spin_unlock_irq(¤t->sighand->siglock); 375 return 0; 376 } 377 378 EXPORT_SYMBOL(allow_signal); 379 380 int disallow_signal(int sig) 381 { 382 if (!valid_signal(sig) || sig < 1) 383 return -EINVAL; 384 385 spin_lock_irq(¤t->sighand->siglock); 386 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN; 387 recalc_sigpending(); 388 spin_unlock_irq(¤t->sighand->siglock); 389 return 0; 390 } 391 392 EXPORT_SYMBOL(disallow_signal); 393 394 /* 395 * Put all the gunge required to become a kernel thread without 396 * attached user resources in one place where it belongs. 397 */ 398 399 void daemonize(const char *name, ...) 400 { 401 va_list args; 402 struct fs_struct *fs; 403 sigset_t blocked; 404 405 va_start(args, name); 406 vsnprintf(current->comm, sizeof(current->comm), name, args); 407 va_end(args); 408 409 /* 410 * If we were started as result of loading a module, close all of the 411 * user space pages. We don't need them, and if we didn't close them 412 * they would be locked into memory. 413 */ 414 exit_mm(current); 415 /* 416 * We don't want to have TIF_FREEZE set if the system-wide hibernation 417 * or suspend transition begins right now. 418 */ 419 current->flags |= PF_NOFREEZE; 420 421 if (current->nsproxy != &init_nsproxy) { 422 get_nsproxy(&init_nsproxy); 423 switch_task_namespaces(current, &init_nsproxy); 424 } 425 set_special_pids(&init_struct_pid); 426 proc_clear_tty(current); 427 428 /* Block and flush all signals */ 429 sigfillset(&blocked); 430 sigprocmask(SIG_BLOCK, &blocked, NULL); 431 flush_signals(current); 432 433 /* Become as one with the init task */ 434 435 exit_fs(current); /* current->fs->count--; */ 436 fs = init_task.fs; 437 current->fs = fs; 438 atomic_inc(&fs->count); 439 440 exit_files(current); 441 current->files = init_task.files; 442 atomic_inc(¤t->files->count); 443 444 reparent_to_kthreadd(); 445 } 446 447 EXPORT_SYMBOL(daemonize); 448 449 static void close_files(struct files_struct * files) 450 { 451 int i, j; 452 struct fdtable *fdt; 453 454 j = 0; 455 456 /* 457 * It is safe to dereference the fd table without RCU or 458 * ->file_lock because this is the last reference to the 459 * files structure. 460 */ 461 fdt = files_fdtable(files); 462 for (;;) { 463 unsigned long set; 464 i = j * __NFDBITS; 465 if (i >= fdt->max_fds) 466 break; 467 set = fdt->open_fds->fds_bits[j++]; 468 while (set) { 469 if (set & 1) { 470 struct file * file = xchg(&fdt->fd[i], NULL); 471 if (file) { 472 filp_close(file, files); 473 cond_resched(); 474 } 475 } 476 i++; 477 set >>= 1; 478 } 479 } 480 } 481 482 struct files_struct *get_files_struct(struct task_struct *task) 483 { 484 struct files_struct *files; 485 486 task_lock(task); 487 files = task->files; 488 if (files) 489 atomic_inc(&files->count); 490 task_unlock(task); 491 492 return files; 493 } 494 495 void put_files_struct(struct files_struct *files) 496 { 497 struct fdtable *fdt; 498 499 if (atomic_dec_and_test(&files->count)) { 500 close_files(files); 501 /* 502 * Free the fd and fdset arrays if we expanded them. 503 * If the fdtable was embedded, pass files for freeing 504 * at the end of the RCU grace period. Otherwise, 505 * you can free files immediately. 506 */ 507 fdt = files_fdtable(files); 508 if (fdt != &files->fdtab) 509 kmem_cache_free(files_cachep, files); 510 free_fdtable(fdt); 511 } 512 } 513 514 void reset_files_struct(struct files_struct *files) 515 { 516 struct task_struct *tsk = current; 517 struct files_struct *old; 518 519 old = tsk->files; 520 task_lock(tsk); 521 tsk->files = files; 522 task_unlock(tsk); 523 put_files_struct(old); 524 } 525 526 void exit_files(struct task_struct *tsk) 527 { 528 struct files_struct * files = tsk->files; 529 530 if (files) { 531 task_lock(tsk); 532 tsk->files = NULL; 533 task_unlock(tsk); 534 put_files_struct(files); 535 } 536 } 537 538 void put_fs_struct(struct fs_struct *fs) 539 { 540 /* No need to hold fs->lock if we are killing it */ 541 if (atomic_dec_and_test(&fs->count)) { 542 path_put(&fs->root); 543 path_put(&fs->pwd); 544 if (fs->altroot.dentry) 545 path_put(&fs->altroot); 546 kmem_cache_free(fs_cachep, fs); 547 } 548 } 549 550 void exit_fs(struct task_struct *tsk) 551 { 552 struct fs_struct * fs = tsk->fs; 553 554 if (fs) { 555 task_lock(tsk); 556 tsk->fs = NULL; 557 task_unlock(tsk); 558 put_fs_struct(fs); 559 } 560 } 561 562 EXPORT_SYMBOL_GPL(exit_fs); 563 564 #ifdef CONFIG_MM_OWNER 565 /* 566 * Task p is exiting and it owned mm, lets find a new owner for it 567 */ 568 static inline int 569 mm_need_new_owner(struct mm_struct *mm, struct task_struct *p) 570 { 571 /* 572 * If there are other users of the mm and the owner (us) is exiting 573 * we need to find a new owner to take on the responsibility. 574 */ 575 if (!mm) 576 return 0; 577 if (atomic_read(&mm->mm_users) <= 1) 578 return 0; 579 if (mm->owner != p) 580 return 0; 581 return 1; 582 } 583 584 void mm_update_next_owner(struct mm_struct *mm) 585 { 586 struct task_struct *c, *g, *p = current; 587 588 retry: 589 if (!mm_need_new_owner(mm, p)) 590 return; 591 592 read_lock(&tasklist_lock); 593 /* 594 * Search in the children 595 */ 596 list_for_each_entry(c, &p->children, sibling) { 597 if (c->mm == mm) 598 goto assign_new_owner; 599 } 600 601 /* 602 * Search in the siblings 603 */ 604 list_for_each_entry(c, &p->parent->children, sibling) { 605 if (c->mm == mm) 606 goto assign_new_owner; 607 } 608 609 /* 610 * Search through everything else. We should not get 611 * here often 612 */ 613 do_each_thread(g, c) { 614 if (c->mm == mm) 615 goto assign_new_owner; 616 } while_each_thread(g, c); 617 618 read_unlock(&tasklist_lock); 619 return; 620 621 assign_new_owner: 622 BUG_ON(c == p); 623 get_task_struct(c); 624 /* 625 * The task_lock protects c->mm from changing. 626 * We always want mm->owner->mm == mm 627 */ 628 task_lock(c); 629 /* 630 * Delay read_unlock() till we have the task_lock() 631 * to ensure that c does not slip away underneath us 632 */ 633 read_unlock(&tasklist_lock); 634 if (c->mm != mm) { 635 task_unlock(c); 636 put_task_struct(c); 637 goto retry; 638 } 639 cgroup_mm_owner_callbacks(mm->owner, c); 640 mm->owner = c; 641 task_unlock(c); 642 put_task_struct(c); 643 } 644 #endif /* CONFIG_MM_OWNER */ 645 646 /* 647 * Turn us into a lazy TLB process if we 648 * aren't already.. 649 */ 650 static void exit_mm(struct task_struct * tsk) 651 { 652 struct mm_struct *mm = tsk->mm; 653 654 mm_release(tsk, mm); 655 if (!mm) 656 return; 657 /* 658 * Serialize with any possible pending coredump. 659 * We must hold mmap_sem around checking core_waiters 660 * and clearing tsk->mm. The core-inducing thread 661 * will increment core_waiters for each thread in the 662 * group with ->mm != NULL. 663 */ 664 down_read(&mm->mmap_sem); 665 if (mm->core_waiters) { 666 up_read(&mm->mmap_sem); 667 down_write(&mm->mmap_sem); 668 if (!--mm->core_waiters) 669 complete(mm->core_startup_done); 670 up_write(&mm->mmap_sem); 671 672 wait_for_completion(&mm->core_done); 673 down_read(&mm->mmap_sem); 674 } 675 atomic_inc(&mm->mm_count); 676 BUG_ON(mm != tsk->active_mm); 677 /* more a memory barrier than a real lock */ 678 task_lock(tsk); 679 tsk->mm = NULL; 680 up_read(&mm->mmap_sem); 681 enter_lazy_tlb(mm, current); 682 /* We don't want this task to be frozen prematurely */ 683 clear_freeze_flag(tsk); 684 task_unlock(tsk); 685 mm_update_next_owner(mm); 686 mmput(mm); 687 } 688 689 static void 690 reparent_thread(struct task_struct *p, struct task_struct *father, int traced) 691 { 692 if (p->pdeath_signal) 693 /* We already hold the tasklist_lock here. */ 694 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p); 695 696 /* Move the child from its dying parent to the new one. */ 697 if (unlikely(traced)) { 698 /* Preserve ptrace links if someone else is tracing this child. */ 699 list_del_init(&p->ptrace_list); 700 if (ptrace_reparented(p)) 701 list_add(&p->ptrace_list, &p->real_parent->ptrace_children); 702 } else { 703 /* If this child is being traced, then we're the one tracing it 704 * anyway, so let go of it. 705 */ 706 p->ptrace = 0; 707 remove_parent(p); 708 p->parent = p->real_parent; 709 add_parent(p); 710 711 if (task_is_traced(p)) { 712 /* 713 * If it was at a trace stop, turn it into 714 * a normal stop since it's no longer being 715 * traced. 716 */ 717 ptrace_untrace(p); 718 } 719 } 720 721 /* If this is a threaded reparent there is no need to 722 * notify anyone anything has happened. 723 */ 724 if (same_thread_group(p->real_parent, father)) 725 return; 726 727 /* We don't want people slaying init. */ 728 if (!task_detached(p)) 729 p->exit_signal = SIGCHLD; 730 731 /* If we'd notified the old parent about this child's death, 732 * also notify the new parent. 733 */ 734 if (!traced && p->exit_state == EXIT_ZOMBIE && 735 !task_detached(p) && thread_group_empty(p)) 736 do_notify_parent(p, p->exit_signal); 737 738 kill_orphaned_pgrp(p, father); 739 } 740 741 /* 742 * When we die, we re-parent all our children. 743 * Try to give them to another thread in our thread 744 * group, and if no such member exists, give it to 745 * the child reaper process (ie "init") in our pid 746 * space. 747 */ 748 static void forget_original_parent(struct task_struct *father) 749 { 750 struct task_struct *p, *n, *reaper = father; 751 struct list_head ptrace_dead; 752 753 INIT_LIST_HEAD(&ptrace_dead); 754 755 write_lock_irq(&tasklist_lock); 756 757 do { 758 reaper = next_thread(reaper); 759 if (reaper == father) { 760 reaper = task_child_reaper(father); 761 break; 762 } 763 } while (reaper->flags & PF_EXITING); 764 765 /* 766 * There are only two places where our children can be: 767 * 768 * - in our child list 769 * - in our ptraced child list 770 * 771 * Search them and reparent children. 772 */ 773 list_for_each_entry_safe(p, n, &father->children, sibling) { 774 int ptrace; 775 776 ptrace = p->ptrace; 777 778 /* if father isn't the real parent, then ptrace must be enabled */ 779 BUG_ON(father != p->real_parent && !ptrace); 780 781 if (father == p->real_parent) { 782 /* reparent with a reaper, real father it's us */ 783 p->real_parent = reaper; 784 reparent_thread(p, father, 0); 785 } else { 786 /* reparent ptraced task to its real parent */ 787 __ptrace_unlink (p); 788 if (p->exit_state == EXIT_ZOMBIE && !task_detached(p) && 789 thread_group_empty(p)) 790 do_notify_parent(p, p->exit_signal); 791 } 792 793 /* 794 * if the ptraced child is a detached zombie we must collect 795 * it before we exit, or it will remain zombie forever since 796 * we prevented it from self-reap itself while it was being 797 * traced by us, to be able to see it in wait4. 798 */ 799 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && task_detached(p))) 800 list_add(&p->ptrace_list, &ptrace_dead); 801 } 802 803 list_for_each_entry_safe(p, n, &father->ptrace_children, ptrace_list) { 804 p->real_parent = reaper; 805 reparent_thread(p, father, 1); 806 } 807 808 write_unlock_irq(&tasklist_lock); 809 BUG_ON(!list_empty(&father->children)); 810 BUG_ON(!list_empty(&father->ptrace_children)); 811 812 list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_list) { 813 list_del_init(&p->ptrace_list); 814 release_task(p); 815 } 816 817 } 818 819 /* 820 * Send signals to all our closest relatives so that they know 821 * to properly mourn us.. 822 */ 823 static void exit_notify(struct task_struct *tsk, int group_dead) 824 { 825 int state; 826 827 /* 828 * This does two things: 829 * 830 * A. Make init inherit all the child processes 831 * B. Check to see if any process groups have become orphaned 832 * as a result of our exiting, and if they have any stopped 833 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 834 */ 835 forget_original_parent(tsk); 836 exit_task_namespaces(tsk); 837 838 write_lock_irq(&tasklist_lock); 839 if (group_dead) 840 kill_orphaned_pgrp(tsk->group_leader, NULL); 841 842 /* Let father know we died 843 * 844 * Thread signals are configurable, but you aren't going to use 845 * that to send signals to arbitary processes. 846 * That stops right now. 847 * 848 * If the parent exec id doesn't match the exec id we saved 849 * when we started then we know the parent has changed security 850 * domain. 851 * 852 * If our self_exec id doesn't match our parent_exec_id then 853 * we have changed execution domain as these two values started 854 * the same after a fork. 855 */ 856 if (tsk->exit_signal != SIGCHLD && !task_detached(tsk) && 857 (tsk->parent_exec_id != tsk->real_parent->self_exec_id || 858 tsk->self_exec_id != tsk->parent_exec_id) && 859 !capable(CAP_KILL)) 860 tsk->exit_signal = SIGCHLD; 861 862 /* If something other than our normal parent is ptracing us, then 863 * send it a SIGCHLD instead of honoring exit_signal. exit_signal 864 * only has special meaning to our real parent. 865 */ 866 if (!task_detached(tsk) && thread_group_empty(tsk)) { 867 int signal = ptrace_reparented(tsk) ? 868 SIGCHLD : tsk->exit_signal; 869 do_notify_parent(tsk, signal); 870 } else if (tsk->ptrace) { 871 do_notify_parent(tsk, SIGCHLD); 872 } 873 874 state = EXIT_ZOMBIE; 875 if (task_detached(tsk) && likely(!tsk->ptrace)) 876 state = EXIT_DEAD; 877 tsk->exit_state = state; 878 879 /* mt-exec, de_thread() is waiting for us */ 880 if (thread_group_leader(tsk) && 881 tsk->signal->notify_count < 0 && 882 tsk->signal->group_exit_task) 883 wake_up_process(tsk->signal->group_exit_task); 884 885 write_unlock_irq(&tasklist_lock); 886 887 /* If the process is dead, release it - nobody will wait for it */ 888 if (state == EXIT_DEAD) 889 release_task(tsk); 890 } 891 892 #ifdef CONFIG_DEBUG_STACK_USAGE 893 static void check_stack_usage(void) 894 { 895 static DEFINE_SPINLOCK(low_water_lock); 896 static int lowest_to_date = THREAD_SIZE; 897 unsigned long *n = end_of_stack(current); 898 unsigned long free; 899 900 while (*n == 0) 901 n++; 902 free = (unsigned long)n - (unsigned long)end_of_stack(current); 903 904 if (free >= lowest_to_date) 905 return; 906 907 spin_lock(&low_water_lock); 908 if (free < lowest_to_date) { 909 printk(KERN_WARNING "%s used greatest stack depth: %lu bytes " 910 "left\n", 911 current->comm, free); 912 lowest_to_date = free; 913 } 914 spin_unlock(&low_water_lock); 915 } 916 #else 917 static inline void check_stack_usage(void) {} 918 #endif 919 920 static inline void exit_child_reaper(struct task_struct *tsk) 921 { 922 if (likely(tsk->group_leader != task_child_reaper(tsk))) 923 return; 924 925 if (tsk->nsproxy->pid_ns == &init_pid_ns) 926 panic("Attempted to kill init!"); 927 928 /* 929 * @tsk is the last thread in the 'cgroup-init' and is exiting. 930 * Terminate all remaining processes in the namespace and reap them 931 * before exiting @tsk. 932 * 933 * Note that @tsk (last thread of cgroup-init) may not necessarily 934 * be the child-reaper (i.e main thread of cgroup-init) of the 935 * namespace i.e the child_reaper may have already exited. 936 * 937 * Even after a child_reaper exits, we let it inherit orphaned children, 938 * because, pid_ns->child_reaper remains valid as long as there is 939 * at least one living sub-thread in the cgroup init. 940 941 * This living sub-thread of the cgroup-init will be notified when 942 * a child inherited by the 'child-reaper' exits (do_notify_parent() 943 * uses __group_send_sig_info()). Further, when reaping child processes, 944 * do_wait() iterates over children of all living sub threads. 945 946 * i.e even though 'child_reaper' thread is listed as the parent of the 947 * orphaned children, any living sub-thread in the cgroup-init can 948 * perform the role of the child_reaper. 949 */ 950 zap_pid_ns_processes(tsk->nsproxy->pid_ns); 951 } 952 953 NORET_TYPE void do_exit(long code) 954 { 955 struct task_struct *tsk = current; 956 int group_dead; 957 958 profile_task_exit(tsk); 959 960 WARN_ON(atomic_read(&tsk->fs_excl)); 961 962 if (unlikely(in_interrupt())) 963 panic("Aiee, killing interrupt handler!"); 964 if (unlikely(!tsk->pid)) 965 panic("Attempted to kill the idle task!"); 966 967 if (unlikely(current->ptrace & PT_TRACE_EXIT)) { 968 current->ptrace_message = code; 969 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP); 970 } 971 972 /* 973 * We're taking recursive faults here in do_exit. Safest is to just 974 * leave this task alone and wait for reboot. 975 */ 976 if (unlikely(tsk->flags & PF_EXITING)) { 977 printk(KERN_ALERT 978 "Fixing recursive fault but reboot is needed!\n"); 979 /* 980 * We can do this unlocked here. The futex code uses 981 * this flag just to verify whether the pi state 982 * cleanup has been done or not. In the worst case it 983 * loops once more. We pretend that the cleanup was 984 * done as there is no way to return. Either the 985 * OWNER_DIED bit is set by now or we push the blocked 986 * task into the wait for ever nirwana as well. 987 */ 988 tsk->flags |= PF_EXITPIDONE; 989 if (tsk->io_context) 990 exit_io_context(); 991 set_current_state(TASK_UNINTERRUPTIBLE); 992 schedule(); 993 } 994 995 exit_signals(tsk); /* sets PF_EXITING */ 996 /* 997 * tsk->flags are checked in the futex code to protect against 998 * an exiting task cleaning up the robust pi futexes. 999 */ 1000 smp_mb(); 1001 spin_unlock_wait(&tsk->pi_lock); 1002 1003 if (unlikely(in_atomic())) 1004 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n", 1005 current->comm, task_pid_nr(current), 1006 preempt_count()); 1007 1008 acct_update_integrals(tsk); 1009 if (tsk->mm) { 1010 update_hiwater_rss(tsk->mm); 1011 update_hiwater_vm(tsk->mm); 1012 } 1013 group_dead = atomic_dec_and_test(&tsk->signal->live); 1014 if (group_dead) { 1015 exit_child_reaper(tsk); 1016 hrtimer_cancel(&tsk->signal->real_timer); 1017 exit_itimers(tsk->signal); 1018 } 1019 acct_collect(code, group_dead); 1020 #ifdef CONFIG_FUTEX 1021 if (unlikely(tsk->robust_list)) 1022 exit_robust_list(tsk); 1023 #ifdef CONFIG_COMPAT 1024 if (unlikely(tsk->compat_robust_list)) 1025 compat_exit_robust_list(tsk); 1026 #endif 1027 #endif 1028 if (group_dead) 1029 tty_audit_exit(); 1030 if (unlikely(tsk->audit_context)) 1031 audit_free(tsk); 1032 1033 tsk->exit_code = code; 1034 taskstats_exit(tsk, group_dead); 1035 1036 exit_mm(tsk); 1037 1038 if (group_dead) 1039 acct_process(); 1040 exit_sem(tsk); 1041 exit_files(tsk); 1042 exit_fs(tsk); 1043 check_stack_usage(); 1044 exit_thread(); 1045 cgroup_exit(tsk, 1); 1046 exit_keys(tsk); 1047 1048 if (group_dead && tsk->signal->leader) 1049 disassociate_ctty(1); 1050 1051 module_put(task_thread_info(tsk)->exec_domain->module); 1052 if (tsk->binfmt) 1053 module_put(tsk->binfmt->module); 1054 1055 proc_exit_connector(tsk); 1056 exit_notify(tsk, group_dead); 1057 #ifdef CONFIG_NUMA 1058 mpol_put(tsk->mempolicy); 1059 tsk->mempolicy = NULL; 1060 #endif 1061 #ifdef CONFIG_FUTEX 1062 /* 1063 * This must happen late, after the PID is not 1064 * hashed anymore: 1065 */ 1066 if (unlikely(!list_empty(&tsk->pi_state_list))) 1067 exit_pi_state_list(tsk); 1068 if (unlikely(current->pi_state_cache)) 1069 kfree(current->pi_state_cache); 1070 #endif 1071 /* 1072 * Make sure we are holding no locks: 1073 */ 1074 debug_check_no_locks_held(tsk); 1075 /* 1076 * We can do this unlocked here. The futex code uses this flag 1077 * just to verify whether the pi state cleanup has been done 1078 * or not. In the worst case it loops once more. 1079 */ 1080 tsk->flags |= PF_EXITPIDONE; 1081 1082 if (tsk->io_context) 1083 exit_io_context(); 1084 1085 if (tsk->splice_pipe) 1086 __free_pipe_info(tsk->splice_pipe); 1087 1088 preempt_disable(); 1089 /* causes final put_task_struct in finish_task_switch(). */ 1090 tsk->state = TASK_DEAD; 1091 1092 schedule(); 1093 BUG(); 1094 /* Avoid "noreturn function does return". */ 1095 for (;;) 1096 cpu_relax(); /* For when BUG is null */ 1097 } 1098 1099 EXPORT_SYMBOL_GPL(do_exit); 1100 1101 NORET_TYPE void complete_and_exit(struct completion *comp, long code) 1102 { 1103 if (comp) 1104 complete(comp); 1105 1106 do_exit(code); 1107 } 1108 1109 EXPORT_SYMBOL(complete_and_exit); 1110 1111 asmlinkage long sys_exit(int error_code) 1112 { 1113 do_exit((error_code&0xff)<<8); 1114 } 1115 1116 /* 1117 * Take down every thread in the group. This is called by fatal signals 1118 * as well as by sys_exit_group (below). 1119 */ 1120 NORET_TYPE void 1121 do_group_exit(int exit_code) 1122 { 1123 struct signal_struct *sig = current->signal; 1124 1125 BUG_ON(exit_code & 0x80); /* core dumps don't get here */ 1126 1127 if (signal_group_exit(sig)) 1128 exit_code = sig->group_exit_code; 1129 else if (!thread_group_empty(current)) { 1130 struct sighand_struct *const sighand = current->sighand; 1131 spin_lock_irq(&sighand->siglock); 1132 if (signal_group_exit(sig)) 1133 /* Another thread got here before we took the lock. */ 1134 exit_code = sig->group_exit_code; 1135 else { 1136 sig->group_exit_code = exit_code; 1137 sig->flags = SIGNAL_GROUP_EXIT; 1138 zap_other_threads(current); 1139 } 1140 spin_unlock_irq(&sighand->siglock); 1141 } 1142 1143 do_exit(exit_code); 1144 /* NOTREACHED */ 1145 } 1146 1147 /* 1148 * this kills every thread in the thread group. Note that any externally 1149 * wait4()-ing process will get the correct exit code - even if this 1150 * thread is not the thread group leader. 1151 */ 1152 asmlinkage void sys_exit_group(int error_code) 1153 { 1154 do_group_exit((error_code & 0xff) << 8); 1155 } 1156 1157 static struct pid *task_pid_type(struct task_struct *task, enum pid_type type) 1158 { 1159 struct pid *pid = NULL; 1160 if (type == PIDTYPE_PID) 1161 pid = task->pids[type].pid; 1162 else if (type < PIDTYPE_MAX) 1163 pid = task->group_leader->pids[type].pid; 1164 return pid; 1165 } 1166 1167 static int eligible_child(enum pid_type type, struct pid *pid, int options, 1168 struct task_struct *p) 1169 { 1170 int err; 1171 1172 if (type < PIDTYPE_MAX) { 1173 if (task_pid_type(p, type) != pid) 1174 return 0; 1175 } 1176 1177 /* 1178 * Do not consider detached threads that are 1179 * not ptraced: 1180 */ 1181 if (task_detached(p) && !p->ptrace) 1182 return 0; 1183 1184 /* Wait for all children (clone and not) if __WALL is set; 1185 * otherwise, wait for clone children *only* if __WCLONE is 1186 * set; otherwise, wait for non-clone children *only*. (Note: 1187 * A "clone" child here is one that reports to its parent 1188 * using a signal other than SIGCHLD.) */ 1189 if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0)) 1190 && !(options & __WALL)) 1191 return 0; 1192 1193 err = security_task_wait(p); 1194 if (likely(!err)) 1195 return 1; 1196 1197 if (type != PIDTYPE_PID) 1198 return 0; 1199 /* This child was explicitly requested, abort */ 1200 read_unlock(&tasklist_lock); 1201 return err; 1202 } 1203 1204 static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid, 1205 int why, int status, 1206 struct siginfo __user *infop, 1207 struct rusage __user *rusagep) 1208 { 1209 int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0; 1210 1211 put_task_struct(p); 1212 if (!retval) 1213 retval = put_user(SIGCHLD, &infop->si_signo); 1214 if (!retval) 1215 retval = put_user(0, &infop->si_errno); 1216 if (!retval) 1217 retval = put_user((short)why, &infop->si_code); 1218 if (!retval) 1219 retval = put_user(pid, &infop->si_pid); 1220 if (!retval) 1221 retval = put_user(uid, &infop->si_uid); 1222 if (!retval) 1223 retval = put_user(status, &infop->si_status); 1224 if (!retval) 1225 retval = pid; 1226 return retval; 1227 } 1228 1229 /* 1230 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold 1231 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1232 * the lock and this task is uninteresting. If we return nonzero, we have 1233 * released the lock and the system call should return. 1234 */ 1235 static int wait_task_zombie(struct task_struct *p, int noreap, 1236 struct siginfo __user *infop, 1237 int __user *stat_addr, struct rusage __user *ru) 1238 { 1239 unsigned long state; 1240 int retval, status, traced; 1241 pid_t pid = task_pid_vnr(p); 1242 1243 if (unlikely(noreap)) { 1244 uid_t uid = p->uid; 1245 int exit_code = p->exit_code; 1246 int why, status; 1247 1248 get_task_struct(p); 1249 read_unlock(&tasklist_lock); 1250 if ((exit_code & 0x7f) == 0) { 1251 why = CLD_EXITED; 1252 status = exit_code >> 8; 1253 } else { 1254 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED; 1255 status = exit_code & 0x7f; 1256 } 1257 return wait_noreap_copyout(p, pid, uid, why, 1258 status, infop, ru); 1259 } 1260 1261 /* 1262 * Try to move the task's state to DEAD 1263 * only one thread is allowed to do this: 1264 */ 1265 state = xchg(&p->exit_state, EXIT_DEAD); 1266 if (state != EXIT_ZOMBIE) { 1267 BUG_ON(state != EXIT_DEAD); 1268 return 0; 1269 } 1270 1271 traced = ptrace_reparented(p); 1272 1273 if (likely(!traced)) { 1274 struct signal_struct *psig; 1275 struct signal_struct *sig; 1276 1277 /* 1278 * The resource counters for the group leader are in its 1279 * own task_struct. Those for dead threads in the group 1280 * are in its signal_struct, as are those for the child 1281 * processes it has previously reaped. All these 1282 * accumulate in the parent's signal_struct c* fields. 1283 * 1284 * We don't bother to take a lock here to protect these 1285 * p->signal fields, because they are only touched by 1286 * __exit_signal, which runs with tasklist_lock 1287 * write-locked anyway, and so is excluded here. We do 1288 * need to protect the access to p->parent->signal fields, 1289 * as other threads in the parent group can be right 1290 * here reaping other children at the same time. 1291 */ 1292 spin_lock_irq(&p->parent->sighand->siglock); 1293 psig = p->parent->signal; 1294 sig = p->signal; 1295 psig->cutime = 1296 cputime_add(psig->cutime, 1297 cputime_add(p->utime, 1298 cputime_add(sig->utime, 1299 sig->cutime))); 1300 psig->cstime = 1301 cputime_add(psig->cstime, 1302 cputime_add(p->stime, 1303 cputime_add(sig->stime, 1304 sig->cstime))); 1305 psig->cgtime = 1306 cputime_add(psig->cgtime, 1307 cputime_add(p->gtime, 1308 cputime_add(sig->gtime, 1309 sig->cgtime))); 1310 psig->cmin_flt += 1311 p->min_flt + sig->min_flt + sig->cmin_flt; 1312 psig->cmaj_flt += 1313 p->maj_flt + sig->maj_flt + sig->cmaj_flt; 1314 psig->cnvcsw += 1315 p->nvcsw + sig->nvcsw + sig->cnvcsw; 1316 psig->cnivcsw += 1317 p->nivcsw + sig->nivcsw + sig->cnivcsw; 1318 psig->cinblock += 1319 task_io_get_inblock(p) + 1320 sig->inblock + sig->cinblock; 1321 psig->coublock += 1322 task_io_get_oublock(p) + 1323 sig->oublock + sig->coublock; 1324 spin_unlock_irq(&p->parent->sighand->siglock); 1325 } 1326 1327 /* 1328 * Now we are sure this task is interesting, and no other 1329 * thread can reap it because we set its state to EXIT_DEAD. 1330 */ 1331 read_unlock(&tasklist_lock); 1332 1333 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; 1334 status = (p->signal->flags & SIGNAL_GROUP_EXIT) 1335 ? p->signal->group_exit_code : p->exit_code; 1336 if (!retval && stat_addr) 1337 retval = put_user(status, stat_addr); 1338 if (!retval && infop) 1339 retval = put_user(SIGCHLD, &infop->si_signo); 1340 if (!retval && infop) 1341 retval = put_user(0, &infop->si_errno); 1342 if (!retval && infop) { 1343 int why; 1344 1345 if ((status & 0x7f) == 0) { 1346 why = CLD_EXITED; 1347 status >>= 8; 1348 } else { 1349 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; 1350 status &= 0x7f; 1351 } 1352 retval = put_user((short)why, &infop->si_code); 1353 if (!retval) 1354 retval = put_user(status, &infop->si_status); 1355 } 1356 if (!retval && infop) 1357 retval = put_user(pid, &infop->si_pid); 1358 if (!retval && infop) 1359 retval = put_user(p->uid, &infop->si_uid); 1360 if (!retval) 1361 retval = pid; 1362 1363 if (traced) { 1364 write_lock_irq(&tasklist_lock); 1365 /* We dropped tasklist, ptracer could die and untrace */ 1366 ptrace_unlink(p); 1367 /* 1368 * If this is not a detached task, notify the parent. 1369 * If it's still not detached after that, don't release 1370 * it now. 1371 */ 1372 if (!task_detached(p)) { 1373 do_notify_parent(p, p->exit_signal); 1374 if (!task_detached(p)) { 1375 p->exit_state = EXIT_ZOMBIE; 1376 p = NULL; 1377 } 1378 } 1379 write_unlock_irq(&tasklist_lock); 1380 } 1381 if (p != NULL) 1382 release_task(p); 1383 1384 return retval; 1385 } 1386 1387 /* 1388 * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold 1389 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1390 * the lock and this task is uninteresting. If we return nonzero, we have 1391 * released the lock and the system call should return. 1392 */ 1393 static int wait_task_stopped(struct task_struct *p, 1394 int noreap, struct siginfo __user *infop, 1395 int __user *stat_addr, struct rusage __user *ru) 1396 { 1397 int retval, exit_code, why; 1398 uid_t uid = 0; /* unneeded, required by compiler */ 1399 pid_t pid; 1400 1401 exit_code = 0; 1402 spin_lock_irq(&p->sighand->siglock); 1403 1404 if (unlikely(!task_is_stopped_or_traced(p))) 1405 goto unlock_sig; 1406 1407 if (!(p->ptrace & PT_PTRACED) && p->signal->group_stop_count > 0) 1408 /* 1409 * A group stop is in progress and this is the group leader. 1410 * We won't report until all threads have stopped. 1411 */ 1412 goto unlock_sig; 1413 1414 exit_code = p->exit_code; 1415 if (!exit_code) 1416 goto unlock_sig; 1417 1418 if (!noreap) 1419 p->exit_code = 0; 1420 1421 uid = p->uid; 1422 unlock_sig: 1423 spin_unlock_irq(&p->sighand->siglock); 1424 if (!exit_code) 1425 return 0; 1426 1427 /* 1428 * Now we are pretty sure this task is interesting. 1429 * Make sure it doesn't get reaped out from under us while we 1430 * give up the lock and then examine it below. We don't want to 1431 * keep holding onto the tasklist_lock while we call getrusage and 1432 * possibly take page faults for user memory. 1433 */ 1434 get_task_struct(p); 1435 pid = task_pid_vnr(p); 1436 why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED; 1437 read_unlock(&tasklist_lock); 1438 1439 if (unlikely(noreap)) 1440 return wait_noreap_copyout(p, pid, uid, 1441 why, exit_code, 1442 infop, ru); 1443 1444 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; 1445 if (!retval && stat_addr) 1446 retval = put_user((exit_code << 8) | 0x7f, stat_addr); 1447 if (!retval && infop) 1448 retval = put_user(SIGCHLD, &infop->si_signo); 1449 if (!retval && infop) 1450 retval = put_user(0, &infop->si_errno); 1451 if (!retval && infop) 1452 retval = put_user((short)why, &infop->si_code); 1453 if (!retval && infop) 1454 retval = put_user(exit_code, &infop->si_status); 1455 if (!retval && infop) 1456 retval = put_user(pid, &infop->si_pid); 1457 if (!retval && infop) 1458 retval = put_user(uid, &infop->si_uid); 1459 if (!retval) 1460 retval = pid; 1461 put_task_struct(p); 1462 1463 BUG_ON(!retval); 1464 return retval; 1465 } 1466 1467 /* 1468 * Handle do_wait work for one task in a live, non-stopped state. 1469 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1470 * the lock and this task is uninteresting. If we return nonzero, we have 1471 * released the lock and the system call should return. 1472 */ 1473 static int wait_task_continued(struct task_struct *p, int noreap, 1474 struct siginfo __user *infop, 1475 int __user *stat_addr, struct rusage __user *ru) 1476 { 1477 int retval; 1478 pid_t pid; 1479 uid_t uid; 1480 1481 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) 1482 return 0; 1483 1484 spin_lock_irq(&p->sighand->siglock); 1485 /* Re-check with the lock held. */ 1486 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { 1487 spin_unlock_irq(&p->sighand->siglock); 1488 return 0; 1489 } 1490 if (!noreap) 1491 p->signal->flags &= ~SIGNAL_STOP_CONTINUED; 1492 spin_unlock_irq(&p->sighand->siglock); 1493 1494 pid = task_pid_vnr(p); 1495 uid = p->uid; 1496 get_task_struct(p); 1497 read_unlock(&tasklist_lock); 1498 1499 if (!infop) { 1500 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; 1501 put_task_struct(p); 1502 if (!retval && stat_addr) 1503 retval = put_user(0xffff, stat_addr); 1504 if (!retval) 1505 retval = pid; 1506 } else { 1507 retval = wait_noreap_copyout(p, pid, uid, 1508 CLD_CONTINUED, SIGCONT, 1509 infop, ru); 1510 BUG_ON(retval == 0); 1511 } 1512 1513 return retval; 1514 } 1515 1516 static long do_wait(enum pid_type type, struct pid *pid, int options, 1517 struct siginfo __user *infop, int __user *stat_addr, 1518 struct rusage __user *ru) 1519 { 1520 DECLARE_WAITQUEUE(wait, current); 1521 struct task_struct *tsk; 1522 int flag, retval; 1523 1524 add_wait_queue(¤t->signal->wait_chldexit,&wait); 1525 repeat: 1526 /* If there is nothing that can match our critier just get out */ 1527 retval = -ECHILD; 1528 if ((type < PIDTYPE_MAX) && (!pid || hlist_empty(&pid->tasks[type]))) 1529 goto end; 1530 1531 /* 1532 * We will set this flag if we see any child that might later 1533 * match our criteria, even if we are not able to reap it yet. 1534 */ 1535 flag = retval = 0; 1536 current->state = TASK_INTERRUPTIBLE; 1537 read_lock(&tasklist_lock); 1538 tsk = current; 1539 do { 1540 struct task_struct *p; 1541 1542 list_for_each_entry(p, &tsk->children, sibling) { 1543 int ret = eligible_child(type, pid, options, p); 1544 if (!ret) 1545 continue; 1546 1547 if (unlikely(ret < 0)) { 1548 retval = ret; 1549 } else if (task_is_stopped_or_traced(p)) { 1550 /* 1551 * It's stopped now, so it might later 1552 * continue, exit, or stop again. 1553 */ 1554 flag = 1; 1555 if (!(p->ptrace & PT_PTRACED) && 1556 !(options & WUNTRACED)) 1557 continue; 1558 1559 retval = wait_task_stopped(p, 1560 (options & WNOWAIT), infop, 1561 stat_addr, ru); 1562 } else if (p->exit_state == EXIT_ZOMBIE && 1563 !delay_group_leader(p)) { 1564 /* 1565 * We don't reap group leaders with subthreads. 1566 */ 1567 if (!likely(options & WEXITED)) 1568 continue; 1569 retval = wait_task_zombie(p, 1570 (options & WNOWAIT), infop, 1571 stat_addr, ru); 1572 } else if (p->exit_state != EXIT_DEAD) { 1573 /* 1574 * It's running now, so it might later 1575 * exit, stop, or stop and then continue. 1576 */ 1577 flag = 1; 1578 if (!unlikely(options & WCONTINUED)) 1579 continue; 1580 retval = wait_task_continued(p, 1581 (options & WNOWAIT), infop, 1582 stat_addr, ru); 1583 } 1584 if (retval != 0) /* tasklist_lock released */ 1585 goto end; 1586 } 1587 if (!flag) { 1588 list_for_each_entry(p, &tsk->ptrace_children, 1589 ptrace_list) { 1590 flag = eligible_child(type, pid, options, p); 1591 if (!flag) 1592 continue; 1593 if (likely(flag > 0)) 1594 break; 1595 retval = flag; 1596 goto end; 1597 } 1598 } 1599 if (options & __WNOTHREAD) 1600 break; 1601 tsk = next_thread(tsk); 1602 BUG_ON(tsk->signal != current->signal); 1603 } while (tsk != current); 1604 read_unlock(&tasklist_lock); 1605 1606 if (flag) { 1607 if (options & WNOHANG) 1608 goto end; 1609 retval = -ERESTARTSYS; 1610 if (signal_pending(current)) 1611 goto end; 1612 schedule(); 1613 goto repeat; 1614 } 1615 retval = -ECHILD; 1616 end: 1617 current->state = TASK_RUNNING; 1618 remove_wait_queue(¤t->signal->wait_chldexit,&wait); 1619 if (infop) { 1620 if (retval > 0) 1621 retval = 0; 1622 else { 1623 /* 1624 * For a WNOHANG return, clear out all the fields 1625 * we would set so the user can easily tell the 1626 * difference. 1627 */ 1628 if (!retval) 1629 retval = put_user(0, &infop->si_signo); 1630 if (!retval) 1631 retval = put_user(0, &infop->si_errno); 1632 if (!retval) 1633 retval = put_user(0, &infop->si_code); 1634 if (!retval) 1635 retval = put_user(0, &infop->si_pid); 1636 if (!retval) 1637 retval = put_user(0, &infop->si_uid); 1638 if (!retval) 1639 retval = put_user(0, &infop->si_status); 1640 } 1641 } 1642 return retval; 1643 } 1644 1645 asmlinkage long sys_waitid(int which, pid_t upid, 1646 struct siginfo __user *infop, int options, 1647 struct rusage __user *ru) 1648 { 1649 struct pid *pid = NULL; 1650 enum pid_type type; 1651 long ret; 1652 1653 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED)) 1654 return -EINVAL; 1655 if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) 1656 return -EINVAL; 1657 1658 switch (which) { 1659 case P_ALL: 1660 type = PIDTYPE_MAX; 1661 break; 1662 case P_PID: 1663 type = PIDTYPE_PID; 1664 if (upid <= 0) 1665 return -EINVAL; 1666 break; 1667 case P_PGID: 1668 type = PIDTYPE_PGID; 1669 if (upid <= 0) 1670 return -EINVAL; 1671 break; 1672 default: 1673 return -EINVAL; 1674 } 1675 1676 if (type < PIDTYPE_MAX) 1677 pid = find_get_pid(upid); 1678 ret = do_wait(type, pid, options, infop, NULL, ru); 1679 put_pid(pid); 1680 1681 /* avoid REGPARM breakage on x86: */ 1682 asmlinkage_protect(5, ret, which, upid, infop, options, ru); 1683 return ret; 1684 } 1685 1686 asmlinkage long sys_wait4(pid_t upid, int __user *stat_addr, 1687 int options, struct rusage __user *ru) 1688 { 1689 struct pid *pid = NULL; 1690 enum pid_type type; 1691 long ret; 1692 1693 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| 1694 __WNOTHREAD|__WCLONE|__WALL)) 1695 return -EINVAL; 1696 1697 if (upid == -1) 1698 type = PIDTYPE_MAX; 1699 else if (upid < 0) { 1700 type = PIDTYPE_PGID; 1701 pid = find_get_pid(-upid); 1702 } else if (upid == 0) { 1703 type = PIDTYPE_PGID; 1704 pid = get_pid(task_pgrp(current)); 1705 } else /* upid > 0 */ { 1706 type = PIDTYPE_PID; 1707 pid = find_get_pid(upid); 1708 } 1709 1710 ret = do_wait(type, pid, options | WEXITED, NULL, stat_addr, ru); 1711 put_pid(pid); 1712 1713 /* avoid REGPARM breakage on x86: */ 1714 asmlinkage_protect(4, ret, upid, stat_addr, options, ru); 1715 return ret; 1716 } 1717 1718 #ifdef __ARCH_WANT_SYS_WAITPID 1719 1720 /* 1721 * sys_waitpid() remains for compatibility. waitpid() should be 1722 * implemented by calling sys_wait4() from libc.a. 1723 */ 1724 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options) 1725 { 1726 return sys_wait4(pid, stat_addr, options, NULL); 1727 } 1728 1729 #endif 1730