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/iocontext.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/pipe_fs_i.h> 43 #include <linux/audit.h> /* for audit_free() */ 44 #include <linux/resource.h> 45 #include <linux/blkdev.h> 46 #include <linux/task_io_accounting_ops.h> 47 #include <linux/tracehook.h> 48 #include <linux/fs_struct.h> 49 #include <linux/init_task.h> 50 #include <linux/perf_event.h> 51 #include <trace/events/sched.h> 52 #include <linux/hw_breakpoint.h> 53 #include <linux/oom.h> 54 #include <linux/writeback.h> 55 #include <linux/shm.h> 56 57 #include <asm/uaccess.h> 58 #include <asm/unistd.h> 59 #include <asm/pgtable.h> 60 #include <asm/mmu_context.h> 61 62 static void exit_mm(struct task_struct * tsk); 63 64 static void __unhash_process(struct task_struct *p, bool group_dead) 65 { 66 nr_threads--; 67 detach_pid(p, PIDTYPE_PID); 68 if (group_dead) { 69 detach_pid(p, PIDTYPE_PGID); 70 detach_pid(p, PIDTYPE_SID); 71 72 list_del_rcu(&p->tasks); 73 list_del_init(&p->sibling); 74 __this_cpu_dec(process_counts); 75 } 76 list_del_rcu(&p->thread_group); 77 } 78 79 /* 80 * This function expects the tasklist_lock write-locked. 81 */ 82 static void __exit_signal(struct task_struct *tsk) 83 { 84 struct signal_struct *sig = tsk->signal; 85 bool group_dead = thread_group_leader(tsk); 86 struct sighand_struct *sighand; 87 struct tty_struct *uninitialized_var(tty); 88 89 sighand = rcu_dereference_check(tsk->sighand, 90 lockdep_tasklist_lock_is_held()); 91 spin_lock(&sighand->siglock); 92 93 posix_cpu_timers_exit(tsk); 94 if (group_dead) { 95 posix_cpu_timers_exit_group(tsk); 96 tty = sig->tty; 97 sig->tty = NULL; 98 } else { 99 /* 100 * This can only happen if the caller is de_thread(). 101 * FIXME: this is the temporary hack, we should teach 102 * posix-cpu-timers to handle this case correctly. 103 */ 104 if (unlikely(has_group_leader_pid(tsk))) 105 posix_cpu_timers_exit_group(tsk); 106 107 /* 108 * If there is any task waiting for the group exit 109 * then notify it: 110 */ 111 if (sig->notify_count > 0 && !--sig->notify_count) 112 wake_up_process(sig->group_exit_task); 113 114 if (tsk == sig->curr_target) 115 sig->curr_target = next_thread(tsk); 116 /* 117 * Accumulate here the counters for all threads but the 118 * group leader as they die, so they can be added into 119 * the process-wide totals when those are taken. 120 * The group leader stays around as a zombie as long 121 * as there are other threads. When it gets reaped, 122 * the exit.c code will add its counts into these totals. 123 * We won't ever get here for the group leader, since it 124 * will have been the last reference on the signal_struct. 125 */ 126 sig->utime += tsk->utime; 127 sig->stime += tsk->stime; 128 sig->gtime += tsk->gtime; 129 sig->min_flt += tsk->min_flt; 130 sig->maj_flt += tsk->maj_flt; 131 sig->nvcsw += tsk->nvcsw; 132 sig->nivcsw += tsk->nivcsw; 133 sig->inblock += task_io_get_inblock(tsk); 134 sig->oublock += task_io_get_oublock(tsk); 135 task_io_accounting_add(&sig->ioac, &tsk->ioac); 136 sig->sum_sched_runtime += tsk->se.sum_exec_runtime; 137 } 138 139 sig->nr_threads--; 140 __unhash_process(tsk, group_dead); 141 142 /* 143 * Do this under ->siglock, we can race with another thread 144 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. 145 */ 146 flush_sigqueue(&tsk->pending); 147 tsk->sighand = NULL; 148 spin_unlock(&sighand->siglock); 149 150 __cleanup_sighand(sighand); 151 clear_tsk_thread_flag(tsk,TIF_SIGPENDING); 152 if (group_dead) { 153 flush_sigqueue(&sig->shared_pending); 154 tty_kref_put(tty); 155 } 156 } 157 158 static void delayed_put_task_struct(struct rcu_head *rhp) 159 { 160 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); 161 162 perf_event_delayed_put(tsk); 163 trace_sched_process_free(tsk); 164 put_task_struct(tsk); 165 } 166 167 168 void release_task(struct task_struct * p) 169 { 170 struct task_struct *leader; 171 int zap_leader; 172 repeat: 173 /* don't need to get the RCU readlock here - the process is dead and 174 * can't be modifying its own credentials. But shut RCU-lockdep up */ 175 rcu_read_lock(); 176 atomic_dec(&__task_cred(p)->user->processes); 177 rcu_read_unlock(); 178 179 proc_flush_task(p); 180 181 write_lock_irq(&tasklist_lock); 182 ptrace_release_task(p); 183 __exit_signal(p); 184 185 /* 186 * If we are the last non-leader member of the thread 187 * group, and the leader is zombie, then notify the 188 * group leader's parent process. (if it wants notification.) 189 */ 190 zap_leader = 0; 191 leader = p->group_leader; 192 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) { 193 /* 194 * If we were the last child thread and the leader has 195 * exited already, and the leader's parent ignores SIGCHLD, 196 * then we are the one who should release the leader. 197 */ 198 zap_leader = do_notify_parent(leader, leader->exit_signal); 199 if (zap_leader) 200 leader->exit_state = EXIT_DEAD; 201 } 202 203 write_unlock_irq(&tasklist_lock); 204 release_thread(p); 205 call_rcu(&p->rcu, delayed_put_task_struct); 206 207 p = leader; 208 if (unlikely(zap_leader)) 209 goto repeat; 210 } 211 212 /* 213 * This checks not only the pgrp, but falls back on the pid if no 214 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly 215 * without this... 216 * 217 * The caller must hold rcu lock or the tasklist lock. 218 */ 219 struct pid *session_of_pgrp(struct pid *pgrp) 220 { 221 struct task_struct *p; 222 struct pid *sid = NULL; 223 224 p = pid_task(pgrp, PIDTYPE_PGID); 225 if (p == NULL) 226 p = pid_task(pgrp, PIDTYPE_PID); 227 if (p != NULL) 228 sid = task_session(p); 229 230 return sid; 231 } 232 233 /* 234 * Determine if a process group is "orphaned", according to the POSIX 235 * definition in 2.2.2.52. Orphaned process groups are not to be affected 236 * by terminal-generated stop signals. Newly orphaned process groups are 237 * to receive a SIGHUP and a SIGCONT. 238 * 239 * "I ask you, have you ever known what it is to be an orphan?" 240 */ 241 static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task) 242 { 243 struct task_struct *p; 244 245 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 246 if ((p == ignored_task) || 247 (p->exit_state && thread_group_empty(p)) || 248 is_global_init(p->real_parent)) 249 continue; 250 251 if (task_pgrp(p->real_parent) != pgrp && 252 task_session(p->real_parent) == task_session(p)) 253 return 0; 254 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 255 256 return 1; 257 } 258 259 int is_current_pgrp_orphaned(void) 260 { 261 int retval; 262 263 read_lock(&tasklist_lock); 264 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); 265 read_unlock(&tasklist_lock); 266 267 return retval; 268 } 269 270 static bool has_stopped_jobs(struct pid *pgrp) 271 { 272 struct task_struct *p; 273 274 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 275 if (p->signal->flags & SIGNAL_STOP_STOPPED) 276 return true; 277 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 278 279 return false; 280 } 281 282 /* 283 * Check to see if any process groups have become orphaned as 284 * a result of our exiting, and if they have any stopped jobs, 285 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 286 */ 287 static void 288 kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) 289 { 290 struct pid *pgrp = task_pgrp(tsk); 291 struct task_struct *ignored_task = tsk; 292 293 if (!parent) 294 /* exit: our father is in a different pgrp than 295 * we are and we were the only connection outside. 296 */ 297 parent = tsk->real_parent; 298 else 299 /* reparent: our child is in a different pgrp than 300 * we are, and it was the only connection outside. 301 */ 302 ignored_task = NULL; 303 304 if (task_pgrp(parent) != pgrp && 305 task_session(parent) == task_session(tsk) && 306 will_become_orphaned_pgrp(pgrp, ignored_task) && 307 has_stopped_jobs(pgrp)) { 308 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); 309 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); 310 } 311 } 312 313 void __set_special_pids(struct pid *pid) 314 { 315 struct task_struct *curr = current->group_leader; 316 317 if (task_session(curr) != pid) 318 change_pid(curr, PIDTYPE_SID, pid); 319 320 if (task_pgrp(curr) != pid) 321 change_pid(curr, PIDTYPE_PGID, pid); 322 } 323 324 /* 325 * Let kernel threads use this to say that they allow a certain signal. 326 * Must not be used if kthread was cloned with CLONE_SIGHAND. 327 */ 328 int allow_signal(int sig) 329 { 330 if (!valid_signal(sig) || sig < 1) 331 return -EINVAL; 332 333 spin_lock_irq(¤t->sighand->siglock); 334 /* This is only needed for daemonize()'ed kthreads */ 335 sigdelset(¤t->blocked, sig); 336 /* 337 * Kernel threads handle their own signals. Let the signal code 338 * know it'll be handled, so that they don't get converted to 339 * SIGKILL or just silently dropped. 340 */ 341 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2; 342 recalc_sigpending(); 343 spin_unlock_irq(¤t->sighand->siglock); 344 return 0; 345 } 346 347 EXPORT_SYMBOL(allow_signal); 348 349 int disallow_signal(int sig) 350 { 351 if (!valid_signal(sig) || sig < 1) 352 return -EINVAL; 353 354 spin_lock_irq(¤t->sighand->siglock); 355 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN; 356 recalc_sigpending(); 357 spin_unlock_irq(¤t->sighand->siglock); 358 return 0; 359 } 360 361 EXPORT_SYMBOL(disallow_signal); 362 363 #ifdef CONFIG_MM_OWNER 364 /* 365 * A task is exiting. If it owned this mm, find a new owner for the mm. 366 */ 367 void mm_update_next_owner(struct mm_struct *mm) 368 { 369 struct task_struct *c, *g, *p = current; 370 371 retry: 372 /* 373 * If the exiting or execing task is not the owner, it's 374 * someone else's problem. 375 */ 376 if (mm->owner != p) 377 return; 378 /* 379 * The current owner is exiting/execing and there are no other 380 * candidates. Do not leave the mm pointing to a possibly 381 * freed task structure. 382 */ 383 if (atomic_read(&mm->mm_users) <= 1) { 384 mm->owner = NULL; 385 return; 386 } 387 388 read_lock(&tasklist_lock); 389 /* 390 * Search in the children 391 */ 392 list_for_each_entry(c, &p->children, sibling) { 393 if (c->mm == mm) 394 goto assign_new_owner; 395 } 396 397 /* 398 * Search in the siblings 399 */ 400 list_for_each_entry(c, &p->real_parent->children, sibling) { 401 if (c->mm == mm) 402 goto assign_new_owner; 403 } 404 405 /* 406 * Search through everything else. We should not get 407 * here often 408 */ 409 do_each_thread(g, c) { 410 if (c->mm == mm) 411 goto assign_new_owner; 412 } while_each_thread(g, c); 413 414 read_unlock(&tasklist_lock); 415 /* 416 * We found no owner yet mm_users > 1: this implies that we are 417 * most likely racing with swapoff (try_to_unuse()) or /proc or 418 * ptrace or page migration (get_task_mm()). Mark owner as NULL. 419 */ 420 mm->owner = NULL; 421 return; 422 423 assign_new_owner: 424 BUG_ON(c == p); 425 get_task_struct(c); 426 /* 427 * The task_lock protects c->mm from changing. 428 * We always want mm->owner->mm == mm 429 */ 430 task_lock(c); 431 /* 432 * Delay read_unlock() till we have the task_lock() 433 * to ensure that c does not slip away underneath us 434 */ 435 read_unlock(&tasklist_lock); 436 if (c->mm != mm) { 437 task_unlock(c); 438 put_task_struct(c); 439 goto retry; 440 } 441 mm->owner = c; 442 task_unlock(c); 443 put_task_struct(c); 444 } 445 #endif /* CONFIG_MM_OWNER */ 446 447 /* 448 * Turn us into a lazy TLB process if we 449 * aren't already.. 450 */ 451 static void exit_mm(struct task_struct * tsk) 452 { 453 struct mm_struct *mm = tsk->mm; 454 struct core_state *core_state; 455 456 mm_release(tsk, mm); 457 if (!mm) 458 return; 459 sync_mm_rss(mm); 460 /* 461 * Serialize with any possible pending coredump. 462 * We must hold mmap_sem around checking core_state 463 * and clearing tsk->mm. The core-inducing thread 464 * will increment ->nr_threads for each thread in the 465 * group with ->mm != NULL. 466 */ 467 down_read(&mm->mmap_sem); 468 core_state = mm->core_state; 469 if (core_state) { 470 struct core_thread self; 471 up_read(&mm->mmap_sem); 472 473 self.task = tsk; 474 self.next = xchg(&core_state->dumper.next, &self); 475 /* 476 * Implies mb(), the result of xchg() must be visible 477 * to core_state->dumper. 478 */ 479 if (atomic_dec_and_test(&core_state->nr_threads)) 480 complete(&core_state->startup); 481 482 for (;;) { 483 set_task_state(tsk, TASK_UNINTERRUPTIBLE); 484 if (!self.task) /* see coredump_finish() */ 485 break; 486 schedule(); 487 } 488 __set_task_state(tsk, TASK_RUNNING); 489 down_read(&mm->mmap_sem); 490 } 491 atomic_inc(&mm->mm_count); 492 BUG_ON(mm != tsk->active_mm); 493 /* more a memory barrier than a real lock */ 494 task_lock(tsk); 495 tsk->mm = NULL; 496 up_read(&mm->mmap_sem); 497 enter_lazy_tlb(mm, current); 498 task_unlock(tsk); 499 mm_update_next_owner(mm); 500 mmput(mm); 501 } 502 503 /* 504 * When we die, we re-parent all our children, and try to: 505 * 1. give them to another thread in our thread group, if such a member exists 506 * 2. give it to the first ancestor process which prctl'd itself as a 507 * child_subreaper for its children (like a service manager) 508 * 3. give it to the init process (PID 1) in our pid namespace 509 */ 510 static struct task_struct *find_new_reaper(struct task_struct *father) 511 __releases(&tasklist_lock) 512 __acquires(&tasklist_lock) 513 { 514 struct pid_namespace *pid_ns = task_active_pid_ns(father); 515 struct task_struct *thread; 516 517 thread = father; 518 while_each_thread(father, thread) { 519 if (thread->flags & PF_EXITING) 520 continue; 521 if (unlikely(pid_ns->child_reaper == father)) 522 pid_ns->child_reaper = thread; 523 return thread; 524 } 525 526 if (unlikely(pid_ns->child_reaper == father)) { 527 write_unlock_irq(&tasklist_lock); 528 if (unlikely(pid_ns == &init_pid_ns)) { 529 panic("Attempted to kill init! exitcode=0x%08x\n", 530 father->signal->group_exit_code ?: 531 father->exit_code); 532 } 533 534 zap_pid_ns_processes(pid_ns); 535 write_lock_irq(&tasklist_lock); 536 } else if (father->signal->has_child_subreaper) { 537 struct task_struct *reaper; 538 539 /* 540 * Find the first ancestor marked as child_subreaper. 541 * Note that the code below checks same_thread_group(reaper, 542 * pid_ns->child_reaper). This is what we need to DTRT in a 543 * PID namespace. However we still need the check above, see 544 * http://marc.info/?l=linux-kernel&m=131385460420380 545 */ 546 for (reaper = father->real_parent; 547 reaper != &init_task; 548 reaper = reaper->real_parent) { 549 if (same_thread_group(reaper, pid_ns->child_reaper)) 550 break; 551 if (!reaper->signal->is_child_subreaper) 552 continue; 553 thread = reaper; 554 do { 555 if (!(thread->flags & PF_EXITING)) 556 return reaper; 557 } while_each_thread(reaper, thread); 558 } 559 } 560 561 return pid_ns->child_reaper; 562 } 563 564 /* 565 * Any that need to be release_task'd are put on the @dead list. 566 */ 567 static void reparent_leader(struct task_struct *father, struct task_struct *p, 568 struct list_head *dead) 569 { 570 list_move_tail(&p->sibling, &p->real_parent->children); 571 572 if (p->exit_state == EXIT_DEAD) 573 return; 574 /* 575 * If this is a threaded reparent there is no need to 576 * notify anyone anything has happened. 577 */ 578 if (same_thread_group(p->real_parent, father)) 579 return; 580 581 /* We don't want people slaying init. */ 582 p->exit_signal = SIGCHLD; 583 584 /* If it has exited notify the new parent about this child's death. */ 585 if (!p->ptrace && 586 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { 587 if (do_notify_parent(p, p->exit_signal)) { 588 p->exit_state = EXIT_DEAD; 589 list_move_tail(&p->sibling, dead); 590 } 591 } 592 593 kill_orphaned_pgrp(p, father); 594 } 595 596 static void forget_original_parent(struct task_struct *father) 597 { 598 struct task_struct *p, *n, *reaper; 599 LIST_HEAD(dead_children); 600 601 write_lock_irq(&tasklist_lock); 602 /* 603 * Note that exit_ptrace() and find_new_reaper() might 604 * drop tasklist_lock and reacquire it. 605 */ 606 exit_ptrace(father); 607 reaper = find_new_reaper(father); 608 609 list_for_each_entry_safe(p, n, &father->children, sibling) { 610 struct task_struct *t = p; 611 do { 612 t->real_parent = reaper; 613 if (t->parent == father) { 614 BUG_ON(t->ptrace); 615 t->parent = t->real_parent; 616 } 617 if (t->pdeath_signal) 618 group_send_sig_info(t->pdeath_signal, 619 SEND_SIG_NOINFO, t); 620 } while_each_thread(p, t); 621 reparent_leader(father, p, &dead_children); 622 } 623 write_unlock_irq(&tasklist_lock); 624 625 BUG_ON(!list_empty(&father->children)); 626 627 list_for_each_entry_safe(p, n, &dead_children, sibling) { 628 list_del_init(&p->sibling); 629 release_task(p); 630 } 631 } 632 633 /* 634 * Send signals to all our closest relatives so that they know 635 * to properly mourn us.. 636 */ 637 static void exit_notify(struct task_struct *tsk, int group_dead) 638 { 639 bool autoreap; 640 641 /* 642 * This does two things: 643 * 644 * A. Make init inherit all the child processes 645 * B. Check to see if any process groups have become orphaned 646 * as a result of our exiting, and if they have any stopped 647 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 648 */ 649 forget_original_parent(tsk); 650 exit_task_namespaces(tsk); 651 652 write_lock_irq(&tasklist_lock); 653 if (group_dead) 654 kill_orphaned_pgrp(tsk->group_leader, NULL); 655 656 if (unlikely(tsk->ptrace)) { 657 int sig = thread_group_leader(tsk) && 658 thread_group_empty(tsk) && 659 !ptrace_reparented(tsk) ? 660 tsk->exit_signal : SIGCHLD; 661 autoreap = do_notify_parent(tsk, sig); 662 } else if (thread_group_leader(tsk)) { 663 autoreap = thread_group_empty(tsk) && 664 do_notify_parent(tsk, tsk->exit_signal); 665 } else { 666 autoreap = true; 667 } 668 669 tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE; 670 671 /* mt-exec, de_thread() is waiting for group leader */ 672 if (unlikely(tsk->signal->notify_count < 0)) 673 wake_up_process(tsk->signal->group_exit_task); 674 write_unlock_irq(&tasklist_lock); 675 676 /* If the process is dead, release it - nobody will wait for it */ 677 if (autoreap) 678 release_task(tsk); 679 } 680 681 #ifdef CONFIG_DEBUG_STACK_USAGE 682 static void check_stack_usage(void) 683 { 684 static DEFINE_SPINLOCK(low_water_lock); 685 static int lowest_to_date = THREAD_SIZE; 686 unsigned long free; 687 688 free = stack_not_used(current); 689 690 if (free >= lowest_to_date) 691 return; 692 693 spin_lock(&low_water_lock); 694 if (free < lowest_to_date) { 695 printk(KERN_WARNING "%s (%d) used greatest stack depth: " 696 "%lu bytes left\n", 697 current->comm, task_pid_nr(current), free); 698 lowest_to_date = free; 699 } 700 spin_unlock(&low_water_lock); 701 } 702 #else 703 static inline void check_stack_usage(void) {} 704 #endif 705 706 void do_exit(long code) 707 { 708 struct task_struct *tsk = current; 709 int group_dead; 710 711 profile_task_exit(tsk); 712 713 WARN_ON(blk_needs_flush_plug(tsk)); 714 715 if (unlikely(in_interrupt())) 716 panic("Aiee, killing interrupt handler!"); 717 if (unlikely(!tsk->pid)) 718 panic("Attempted to kill the idle task!"); 719 720 /* 721 * If do_exit is called because this processes oopsed, it's possible 722 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before 723 * continuing. Amongst other possible reasons, this is to prevent 724 * mm_release()->clear_child_tid() from writing to a user-controlled 725 * kernel address. 726 */ 727 set_fs(USER_DS); 728 729 ptrace_event(PTRACE_EVENT_EXIT, code); 730 731 validate_creds_for_do_exit(tsk); 732 733 /* 734 * We're taking recursive faults here in do_exit. Safest is to just 735 * leave this task alone and wait for reboot. 736 */ 737 if (unlikely(tsk->flags & PF_EXITING)) { 738 printk(KERN_ALERT 739 "Fixing recursive fault but reboot is needed!\n"); 740 /* 741 * We can do this unlocked here. The futex code uses 742 * this flag just to verify whether the pi state 743 * cleanup has been done or not. In the worst case it 744 * loops once more. We pretend that the cleanup was 745 * done as there is no way to return. Either the 746 * OWNER_DIED bit is set by now or we push the blocked 747 * task into the wait for ever nirwana as well. 748 */ 749 tsk->flags |= PF_EXITPIDONE; 750 set_current_state(TASK_UNINTERRUPTIBLE); 751 schedule(); 752 } 753 754 exit_signals(tsk); /* sets PF_EXITING */ 755 /* 756 * tsk->flags are checked in the futex code to protect against 757 * an exiting task cleaning up the robust pi futexes. 758 */ 759 smp_mb(); 760 raw_spin_unlock_wait(&tsk->pi_lock); 761 762 if (unlikely(in_atomic())) 763 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n", 764 current->comm, task_pid_nr(current), 765 preempt_count()); 766 767 acct_update_integrals(tsk); 768 /* sync mm's RSS info before statistics gathering */ 769 if (tsk->mm) 770 sync_mm_rss(tsk->mm); 771 group_dead = atomic_dec_and_test(&tsk->signal->live); 772 if (group_dead) { 773 hrtimer_cancel(&tsk->signal->real_timer); 774 exit_itimers(tsk->signal); 775 if (tsk->mm) 776 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); 777 } 778 acct_collect(code, group_dead); 779 if (group_dead) 780 tty_audit_exit(); 781 audit_free(tsk); 782 783 tsk->exit_code = code; 784 taskstats_exit(tsk, group_dead); 785 786 exit_mm(tsk); 787 788 if (group_dead) 789 acct_process(); 790 trace_sched_process_exit(tsk); 791 792 exit_sem(tsk); 793 exit_shm(tsk); 794 exit_files(tsk); 795 exit_fs(tsk); 796 exit_task_work(tsk); 797 check_stack_usage(); 798 exit_thread(); 799 800 /* 801 * Flush inherited counters to the parent - before the parent 802 * gets woken up by child-exit notifications. 803 * 804 * because of cgroup mode, must be called before cgroup_exit() 805 */ 806 perf_event_exit_task(tsk); 807 808 cgroup_exit(tsk, 1); 809 810 if (group_dead) 811 disassociate_ctty(1); 812 813 module_put(task_thread_info(tsk)->exec_domain->module); 814 815 proc_exit_connector(tsk); 816 817 /* 818 * FIXME: do that only when needed, using sched_exit tracepoint 819 */ 820 ptrace_put_breakpoints(tsk); 821 822 exit_notify(tsk, group_dead); 823 #ifdef CONFIG_NUMA 824 task_lock(tsk); 825 mpol_put(tsk->mempolicy); 826 tsk->mempolicy = NULL; 827 task_unlock(tsk); 828 #endif 829 #ifdef CONFIG_FUTEX 830 if (unlikely(current->pi_state_cache)) 831 kfree(current->pi_state_cache); 832 #endif 833 /* 834 * Make sure we are holding no locks: 835 */ 836 debug_check_no_locks_held(tsk); 837 /* 838 * We can do this unlocked here. The futex code uses this flag 839 * just to verify whether the pi state cleanup has been done 840 * or not. In the worst case it loops once more. 841 */ 842 tsk->flags |= PF_EXITPIDONE; 843 844 if (tsk->io_context) 845 exit_io_context(tsk); 846 847 if (tsk->splice_pipe) 848 __free_pipe_info(tsk->splice_pipe); 849 850 if (tsk->task_frag.page) 851 put_page(tsk->task_frag.page); 852 853 validate_creds_for_do_exit(tsk); 854 855 preempt_disable(); 856 if (tsk->nr_dirtied) 857 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); 858 exit_rcu(); 859 860 /* 861 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed 862 * when the following two conditions become true. 863 * - There is race condition of mmap_sem (It is acquired by 864 * exit_mm()), and 865 * - SMI occurs before setting TASK_RUNINNG. 866 * (or hypervisor of virtual machine switches to other guest) 867 * As a result, we may become TASK_RUNNING after becoming TASK_DEAD 868 * 869 * To avoid it, we have to wait for releasing tsk->pi_lock which 870 * is held by try_to_wake_up() 871 */ 872 smp_mb(); 873 raw_spin_unlock_wait(&tsk->pi_lock); 874 875 /* causes final put_task_struct in finish_task_switch(). */ 876 tsk->state = TASK_DEAD; 877 tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */ 878 schedule(); 879 BUG(); 880 /* Avoid "noreturn function does return". */ 881 for (;;) 882 cpu_relax(); /* For when BUG is null */ 883 } 884 885 EXPORT_SYMBOL_GPL(do_exit); 886 887 void complete_and_exit(struct completion *comp, long code) 888 { 889 if (comp) 890 complete(comp); 891 892 do_exit(code); 893 } 894 895 EXPORT_SYMBOL(complete_and_exit); 896 897 SYSCALL_DEFINE1(exit, int, error_code) 898 { 899 do_exit((error_code&0xff)<<8); 900 } 901 902 /* 903 * Take down every thread in the group. This is called by fatal signals 904 * as well as by sys_exit_group (below). 905 */ 906 void 907 do_group_exit(int exit_code) 908 { 909 struct signal_struct *sig = current->signal; 910 911 BUG_ON(exit_code & 0x80); /* core dumps don't get here */ 912 913 if (signal_group_exit(sig)) 914 exit_code = sig->group_exit_code; 915 else if (!thread_group_empty(current)) { 916 struct sighand_struct *const sighand = current->sighand; 917 spin_lock_irq(&sighand->siglock); 918 if (signal_group_exit(sig)) 919 /* Another thread got here before we took the lock. */ 920 exit_code = sig->group_exit_code; 921 else { 922 sig->group_exit_code = exit_code; 923 sig->flags = SIGNAL_GROUP_EXIT; 924 zap_other_threads(current); 925 } 926 spin_unlock_irq(&sighand->siglock); 927 } 928 929 do_exit(exit_code); 930 /* NOTREACHED */ 931 } 932 933 /* 934 * this kills every thread in the thread group. Note that any externally 935 * wait4()-ing process will get the correct exit code - even if this 936 * thread is not the thread group leader. 937 */ 938 SYSCALL_DEFINE1(exit_group, int, error_code) 939 { 940 do_group_exit((error_code & 0xff) << 8); 941 /* NOTREACHED */ 942 return 0; 943 } 944 945 struct wait_opts { 946 enum pid_type wo_type; 947 int wo_flags; 948 struct pid *wo_pid; 949 950 struct siginfo __user *wo_info; 951 int __user *wo_stat; 952 struct rusage __user *wo_rusage; 953 954 wait_queue_t child_wait; 955 int notask_error; 956 }; 957 958 static inline 959 struct pid *task_pid_type(struct task_struct *task, enum pid_type type) 960 { 961 if (type != PIDTYPE_PID) 962 task = task->group_leader; 963 return task->pids[type].pid; 964 } 965 966 static int eligible_pid(struct wait_opts *wo, struct task_struct *p) 967 { 968 return wo->wo_type == PIDTYPE_MAX || 969 task_pid_type(p, wo->wo_type) == wo->wo_pid; 970 } 971 972 static int eligible_child(struct wait_opts *wo, struct task_struct *p) 973 { 974 if (!eligible_pid(wo, p)) 975 return 0; 976 /* Wait for all children (clone and not) if __WALL is set; 977 * otherwise, wait for clone children *only* if __WCLONE is 978 * set; otherwise, wait for non-clone children *only*. (Note: 979 * A "clone" child here is one that reports to its parent 980 * using a signal other than SIGCHLD.) */ 981 if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) 982 && !(wo->wo_flags & __WALL)) 983 return 0; 984 985 return 1; 986 } 987 988 static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p, 989 pid_t pid, uid_t uid, int why, int status) 990 { 991 struct siginfo __user *infop; 992 int retval = wo->wo_rusage 993 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; 994 995 put_task_struct(p); 996 infop = wo->wo_info; 997 if (infop) { 998 if (!retval) 999 retval = put_user(SIGCHLD, &infop->si_signo); 1000 if (!retval) 1001 retval = put_user(0, &infop->si_errno); 1002 if (!retval) 1003 retval = put_user((short)why, &infop->si_code); 1004 if (!retval) 1005 retval = put_user(pid, &infop->si_pid); 1006 if (!retval) 1007 retval = put_user(uid, &infop->si_uid); 1008 if (!retval) 1009 retval = put_user(status, &infop->si_status); 1010 } 1011 if (!retval) 1012 retval = pid; 1013 return retval; 1014 } 1015 1016 /* 1017 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold 1018 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1019 * the lock and this task is uninteresting. If we return nonzero, we have 1020 * released the lock and the system call should return. 1021 */ 1022 static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) 1023 { 1024 unsigned long state; 1025 int retval, status, traced; 1026 pid_t pid = task_pid_vnr(p); 1027 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1028 struct siginfo __user *infop; 1029 1030 if (!likely(wo->wo_flags & WEXITED)) 1031 return 0; 1032 1033 if (unlikely(wo->wo_flags & WNOWAIT)) { 1034 int exit_code = p->exit_code; 1035 int why; 1036 1037 get_task_struct(p); 1038 read_unlock(&tasklist_lock); 1039 if ((exit_code & 0x7f) == 0) { 1040 why = CLD_EXITED; 1041 status = exit_code >> 8; 1042 } else { 1043 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED; 1044 status = exit_code & 0x7f; 1045 } 1046 return wait_noreap_copyout(wo, p, pid, uid, why, status); 1047 } 1048 1049 /* 1050 * Try to move the task's state to DEAD 1051 * only one thread is allowed to do this: 1052 */ 1053 state = xchg(&p->exit_state, EXIT_DEAD); 1054 if (state != EXIT_ZOMBIE) { 1055 BUG_ON(state != EXIT_DEAD); 1056 return 0; 1057 } 1058 1059 traced = ptrace_reparented(p); 1060 /* 1061 * It can be ptraced but not reparented, check 1062 * thread_group_leader() to filter out sub-threads. 1063 */ 1064 if (likely(!traced) && thread_group_leader(p)) { 1065 struct signal_struct *psig; 1066 struct signal_struct *sig; 1067 unsigned long maxrss; 1068 cputime_t tgutime, tgstime; 1069 1070 /* 1071 * The resource counters for the group leader are in its 1072 * own task_struct. Those for dead threads in the group 1073 * are in its signal_struct, as are those for the child 1074 * processes it has previously reaped. All these 1075 * accumulate in the parent's signal_struct c* fields. 1076 * 1077 * We don't bother to take a lock here to protect these 1078 * p->signal fields, because they are only touched by 1079 * __exit_signal, which runs with tasklist_lock 1080 * write-locked anyway, and so is excluded here. We do 1081 * need to protect the access to parent->signal fields, 1082 * as other threads in the parent group can be right 1083 * here reaping other children at the same time. 1084 * 1085 * We use thread_group_cputime_adjusted() to get times for the thread 1086 * group, which consolidates times for all threads in the 1087 * group including the group leader. 1088 */ 1089 thread_group_cputime_adjusted(p, &tgutime, &tgstime); 1090 spin_lock_irq(&p->real_parent->sighand->siglock); 1091 psig = p->real_parent->signal; 1092 sig = p->signal; 1093 psig->cutime += tgutime + sig->cutime; 1094 psig->cstime += tgstime + sig->cstime; 1095 psig->cgtime += p->gtime + sig->gtime + sig->cgtime; 1096 psig->cmin_flt += 1097 p->min_flt + sig->min_flt + sig->cmin_flt; 1098 psig->cmaj_flt += 1099 p->maj_flt + sig->maj_flt + sig->cmaj_flt; 1100 psig->cnvcsw += 1101 p->nvcsw + sig->nvcsw + sig->cnvcsw; 1102 psig->cnivcsw += 1103 p->nivcsw + sig->nivcsw + sig->cnivcsw; 1104 psig->cinblock += 1105 task_io_get_inblock(p) + 1106 sig->inblock + sig->cinblock; 1107 psig->coublock += 1108 task_io_get_oublock(p) + 1109 sig->oublock + sig->coublock; 1110 maxrss = max(sig->maxrss, sig->cmaxrss); 1111 if (psig->cmaxrss < maxrss) 1112 psig->cmaxrss = maxrss; 1113 task_io_accounting_add(&psig->ioac, &p->ioac); 1114 task_io_accounting_add(&psig->ioac, &sig->ioac); 1115 spin_unlock_irq(&p->real_parent->sighand->siglock); 1116 } 1117 1118 /* 1119 * Now we are sure this task is interesting, and no other 1120 * thread can reap it because we set its state to EXIT_DEAD. 1121 */ 1122 read_unlock(&tasklist_lock); 1123 1124 retval = wo->wo_rusage 1125 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; 1126 status = (p->signal->flags & SIGNAL_GROUP_EXIT) 1127 ? p->signal->group_exit_code : p->exit_code; 1128 if (!retval && wo->wo_stat) 1129 retval = put_user(status, wo->wo_stat); 1130 1131 infop = wo->wo_info; 1132 if (!retval && infop) 1133 retval = put_user(SIGCHLD, &infop->si_signo); 1134 if (!retval && infop) 1135 retval = put_user(0, &infop->si_errno); 1136 if (!retval && infop) { 1137 int why; 1138 1139 if ((status & 0x7f) == 0) { 1140 why = CLD_EXITED; 1141 status >>= 8; 1142 } else { 1143 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; 1144 status &= 0x7f; 1145 } 1146 retval = put_user((short)why, &infop->si_code); 1147 if (!retval) 1148 retval = put_user(status, &infop->si_status); 1149 } 1150 if (!retval && infop) 1151 retval = put_user(pid, &infop->si_pid); 1152 if (!retval && infop) 1153 retval = put_user(uid, &infop->si_uid); 1154 if (!retval) 1155 retval = pid; 1156 1157 if (traced) { 1158 write_lock_irq(&tasklist_lock); 1159 /* We dropped tasklist, ptracer could die and untrace */ 1160 ptrace_unlink(p); 1161 /* 1162 * If this is not a sub-thread, notify the parent. 1163 * If parent wants a zombie, don't release it now. 1164 */ 1165 if (thread_group_leader(p) && 1166 !do_notify_parent(p, p->exit_signal)) { 1167 p->exit_state = EXIT_ZOMBIE; 1168 p = NULL; 1169 } 1170 write_unlock_irq(&tasklist_lock); 1171 } 1172 if (p != NULL) 1173 release_task(p); 1174 1175 return retval; 1176 } 1177 1178 static int *task_stopped_code(struct task_struct *p, bool ptrace) 1179 { 1180 if (ptrace) { 1181 if (task_is_stopped_or_traced(p) && 1182 !(p->jobctl & JOBCTL_LISTENING)) 1183 return &p->exit_code; 1184 } else { 1185 if (p->signal->flags & SIGNAL_STOP_STOPPED) 1186 return &p->signal->group_exit_code; 1187 } 1188 return NULL; 1189 } 1190 1191 /** 1192 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED 1193 * @wo: wait options 1194 * @ptrace: is the wait for ptrace 1195 * @p: task to wait for 1196 * 1197 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED. 1198 * 1199 * CONTEXT: 1200 * read_lock(&tasklist_lock), which is released if return value is 1201 * non-zero. Also, grabs and releases @p->sighand->siglock. 1202 * 1203 * RETURNS: 1204 * 0 if wait condition didn't exist and search for other wait conditions 1205 * should continue. Non-zero return, -errno on failure and @p's pid on 1206 * success, implies that tasklist_lock is released and wait condition 1207 * search should terminate. 1208 */ 1209 static int wait_task_stopped(struct wait_opts *wo, 1210 int ptrace, struct task_struct *p) 1211 { 1212 struct siginfo __user *infop; 1213 int retval, exit_code, *p_code, why; 1214 uid_t uid = 0; /* unneeded, required by compiler */ 1215 pid_t pid; 1216 1217 /* 1218 * Traditionally we see ptrace'd stopped tasks regardless of options. 1219 */ 1220 if (!ptrace && !(wo->wo_flags & WUNTRACED)) 1221 return 0; 1222 1223 if (!task_stopped_code(p, ptrace)) 1224 return 0; 1225 1226 exit_code = 0; 1227 spin_lock_irq(&p->sighand->siglock); 1228 1229 p_code = task_stopped_code(p, ptrace); 1230 if (unlikely(!p_code)) 1231 goto unlock_sig; 1232 1233 exit_code = *p_code; 1234 if (!exit_code) 1235 goto unlock_sig; 1236 1237 if (!unlikely(wo->wo_flags & WNOWAIT)) 1238 *p_code = 0; 1239 1240 uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1241 unlock_sig: 1242 spin_unlock_irq(&p->sighand->siglock); 1243 if (!exit_code) 1244 return 0; 1245 1246 /* 1247 * Now we are pretty sure this task is interesting. 1248 * Make sure it doesn't get reaped out from under us while we 1249 * give up the lock and then examine it below. We don't want to 1250 * keep holding onto the tasklist_lock while we call getrusage and 1251 * possibly take page faults for user memory. 1252 */ 1253 get_task_struct(p); 1254 pid = task_pid_vnr(p); 1255 why = ptrace ? CLD_TRAPPED : CLD_STOPPED; 1256 read_unlock(&tasklist_lock); 1257 1258 if (unlikely(wo->wo_flags & WNOWAIT)) 1259 return wait_noreap_copyout(wo, p, pid, uid, why, exit_code); 1260 1261 retval = wo->wo_rusage 1262 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; 1263 if (!retval && wo->wo_stat) 1264 retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat); 1265 1266 infop = wo->wo_info; 1267 if (!retval && infop) 1268 retval = put_user(SIGCHLD, &infop->si_signo); 1269 if (!retval && infop) 1270 retval = put_user(0, &infop->si_errno); 1271 if (!retval && infop) 1272 retval = put_user((short)why, &infop->si_code); 1273 if (!retval && infop) 1274 retval = put_user(exit_code, &infop->si_status); 1275 if (!retval && infop) 1276 retval = put_user(pid, &infop->si_pid); 1277 if (!retval && infop) 1278 retval = put_user(uid, &infop->si_uid); 1279 if (!retval) 1280 retval = pid; 1281 put_task_struct(p); 1282 1283 BUG_ON(!retval); 1284 return retval; 1285 } 1286 1287 /* 1288 * Handle do_wait work for one task in a live, non-stopped state. 1289 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1290 * the lock and this task is uninteresting. If we return nonzero, we have 1291 * released the lock and the system call should return. 1292 */ 1293 static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) 1294 { 1295 int retval; 1296 pid_t pid; 1297 uid_t uid; 1298 1299 if (!unlikely(wo->wo_flags & WCONTINUED)) 1300 return 0; 1301 1302 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) 1303 return 0; 1304 1305 spin_lock_irq(&p->sighand->siglock); 1306 /* Re-check with the lock held. */ 1307 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { 1308 spin_unlock_irq(&p->sighand->siglock); 1309 return 0; 1310 } 1311 if (!unlikely(wo->wo_flags & WNOWAIT)) 1312 p->signal->flags &= ~SIGNAL_STOP_CONTINUED; 1313 uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1314 spin_unlock_irq(&p->sighand->siglock); 1315 1316 pid = task_pid_vnr(p); 1317 get_task_struct(p); 1318 read_unlock(&tasklist_lock); 1319 1320 if (!wo->wo_info) { 1321 retval = wo->wo_rusage 1322 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; 1323 put_task_struct(p); 1324 if (!retval && wo->wo_stat) 1325 retval = put_user(0xffff, wo->wo_stat); 1326 if (!retval) 1327 retval = pid; 1328 } else { 1329 retval = wait_noreap_copyout(wo, p, pid, uid, 1330 CLD_CONTINUED, SIGCONT); 1331 BUG_ON(retval == 0); 1332 } 1333 1334 return retval; 1335 } 1336 1337 /* 1338 * Consider @p for a wait by @parent. 1339 * 1340 * -ECHILD should be in ->notask_error before the first call. 1341 * Returns nonzero for a final return, when we have unlocked tasklist_lock. 1342 * Returns zero if the search for a child should continue; 1343 * then ->notask_error is 0 if @p is an eligible child, 1344 * or another error from security_task_wait(), or still -ECHILD. 1345 */ 1346 static int wait_consider_task(struct wait_opts *wo, int ptrace, 1347 struct task_struct *p) 1348 { 1349 int ret = eligible_child(wo, p); 1350 if (!ret) 1351 return ret; 1352 1353 ret = security_task_wait(p); 1354 if (unlikely(ret < 0)) { 1355 /* 1356 * If we have not yet seen any eligible child, 1357 * then let this error code replace -ECHILD. 1358 * A permission error will give the user a clue 1359 * to look for security policy problems, rather 1360 * than for mysterious wait bugs. 1361 */ 1362 if (wo->notask_error) 1363 wo->notask_error = ret; 1364 return 0; 1365 } 1366 1367 /* dead body doesn't have much to contribute */ 1368 if (unlikely(p->exit_state == EXIT_DEAD)) { 1369 /* 1370 * But do not ignore this task until the tracer does 1371 * wait_task_zombie()->do_notify_parent(). 1372 */ 1373 if (likely(!ptrace) && unlikely(ptrace_reparented(p))) 1374 wo->notask_error = 0; 1375 return 0; 1376 } 1377 1378 /* slay zombie? */ 1379 if (p->exit_state == EXIT_ZOMBIE) { 1380 /* 1381 * A zombie ptracee is only visible to its ptracer. 1382 * Notification and reaping will be cascaded to the real 1383 * parent when the ptracer detaches. 1384 */ 1385 if (likely(!ptrace) && unlikely(p->ptrace)) { 1386 /* it will become visible, clear notask_error */ 1387 wo->notask_error = 0; 1388 return 0; 1389 } 1390 1391 /* we don't reap group leaders with subthreads */ 1392 if (!delay_group_leader(p)) 1393 return wait_task_zombie(wo, p); 1394 1395 /* 1396 * Allow access to stopped/continued state via zombie by 1397 * falling through. Clearing of notask_error is complex. 1398 * 1399 * When !@ptrace: 1400 * 1401 * If WEXITED is set, notask_error should naturally be 1402 * cleared. If not, subset of WSTOPPED|WCONTINUED is set, 1403 * so, if there are live subthreads, there are events to 1404 * wait for. If all subthreads are dead, it's still safe 1405 * to clear - this function will be called again in finite 1406 * amount time once all the subthreads are released and 1407 * will then return without clearing. 1408 * 1409 * When @ptrace: 1410 * 1411 * Stopped state is per-task and thus can't change once the 1412 * target task dies. Only continued and exited can happen. 1413 * Clear notask_error if WCONTINUED | WEXITED. 1414 */ 1415 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED))) 1416 wo->notask_error = 0; 1417 } else { 1418 /* 1419 * If @p is ptraced by a task in its real parent's group, 1420 * hide group stop/continued state when looking at @p as 1421 * the real parent; otherwise, a single stop can be 1422 * reported twice as group and ptrace stops. 1423 * 1424 * If a ptracer wants to distinguish the two events for its 1425 * own children, it should create a separate process which 1426 * takes the role of real parent. 1427 */ 1428 if (likely(!ptrace) && p->ptrace && !ptrace_reparented(p)) 1429 return 0; 1430 1431 /* 1432 * @p is alive and it's gonna stop, continue or exit, so 1433 * there always is something to wait for. 1434 */ 1435 wo->notask_error = 0; 1436 } 1437 1438 /* 1439 * Wait for stopped. Depending on @ptrace, different stopped state 1440 * is used and the two don't interact with each other. 1441 */ 1442 ret = wait_task_stopped(wo, ptrace, p); 1443 if (ret) 1444 return ret; 1445 1446 /* 1447 * Wait for continued. There's only one continued state and the 1448 * ptracer can consume it which can confuse the real parent. Don't 1449 * use WCONTINUED from ptracer. You don't need or want it. 1450 */ 1451 return wait_task_continued(wo, p); 1452 } 1453 1454 /* 1455 * Do the work of do_wait() for one thread in the group, @tsk. 1456 * 1457 * -ECHILD should be in ->notask_error before the first call. 1458 * Returns nonzero for a final return, when we have unlocked tasklist_lock. 1459 * Returns zero if the search for a child should continue; then 1460 * ->notask_error is 0 if there were any eligible children, 1461 * or another error from security_task_wait(), or still -ECHILD. 1462 */ 1463 static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) 1464 { 1465 struct task_struct *p; 1466 1467 list_for_each_entry(p, &tsk->children, sibling) { 1468 int ret = wait_consider_task(wo, 0, p); 1469 if (ret) 1470 return ret; 1471 } 1472 1473 return 0; 1474 } 1475 1476 static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) 1477 { 1478 struct task_struct *p; 1479 1480 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { 1481 int ret = wait_consider_task(wo, 1, p); 1482 if (ret) 1483 return ret; 1484 } 1485 1486 return 0; 1487 } 1488 1489 static int child_wait_callback(wait_queue_t *wait, unsigned mode, 1490 int sync, void *key) 1491 { 1492 struct wait_opts *wo = container_of(wait, struct wait_opts, 1493 child_wait); 1494 struct task_struct *p = key; 1495 1496 if (!eligible_pid(wo, p)) 1497 return 0; 1498 1499 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) 1500 return 0; 1501 1502 return default_wake_function(wait, mode, sync, key); 1503 } 1504 1505 void __wake_up_parent(struct task_struct *p, struct task_struct *parent) 1506 { 1507 __wake_up_sync_key(&parent->signal->wait_chldexit, 1508 TASK_INTERRUPTIBLE, 1, p); 1509 } 1510 1511 static long do_wait(struct wait_opts *wo) 1512 { 1513 struct task_struct *tsk; 1514 int retval; 1515 1516 trace_sched_process_wait(wo->wo_pid); 1517 1518 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); 1519 wo->child_wait.private = current; 1520 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); 1521 repeat: 1522 /* 1523 * If there is nothing that can match our critiera just get out. 1524 * We will clear ->notask_error to zero if we see any child that 1525 * might later match our criteria, even if we are not able to reap 1526 * it yet. 1527 */ 1528 wo->notask_error = -ECHILD; 1529 if ((wo->wo_type < PIDTYPE_MAX) && 1530 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type]))) 1531 goto notask; 1532 1533 set_current_state(TASK_INTERRUPTIBLE); 1534 read_lock(&tasklist_lock); 1535 tsk = current; 1536 do { 1537 retval = do_wait_thread(wo, tsk); 1538 if (retval) 1539 goto end; 1540 1541 retval = ptrace_do_wait(wo, tsk); 1542 if (retval) 1543 goto end; 1544 1545 if (wo->wo_flags & __WNOTHREAD) 1546 break; 1547 } while_each_thread(current, tsk); 1548 read_unlock(&tasklist_lock); 1549 1550 notask: 1551 retval = wo->notask_error; 1552 if (!retval && !(wo->wo_flags & WNOHANG)) { 1553 retval = -ERESTARTSYS; 1554 if (!signal_pending(current)) { 1555 schedule(); 1556 goto repeat; 1557 } 1558 } 1559 end: 1560 __set_current_state(TASK_RUNNING); 1561 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); 1562 return retval; 1563 } 1564 1565 SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, 1566 infop, int, options, struct rusage __user *, ru) 1567 { 1568 struct wait_opts wo; 1569 struct pid *pid = NULL; 1570 enum pid_type type; 1571 long ret; 1572 1573 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED)) 1574 return -EINVAL; 1575 if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) 1576 return -EINVAL; 1577 1578 switch (which) { 1579 case P_ALL: 1580 type = PIDTYPE_MAX; 1581 break; 1582 case P_PID: 1583 type = PIDTYPE_PID; 1584 if (upid <= 0) 1585 return -EINVAL; 1586 break; 1587 case P_PGID: 1588 type = PIDTYPE_PGID; 1589 if (upid <= 0) 1590 return -EINVAL; 1591 break; 1592 default: 1593 return -EINVAL; 1594 } 1595 1596 if (type < PIDTYPE_MAX) 1597 pid = find_get_pid(upid); 1598 1599 wo.wo_type = type; 1600 wo.wo_pid = pid; 1601 wo.wo_flags = options; 1602 wo.wo_info = infop; 1603 wo.wo_stat = NULL; 1604 wo.wo_rusage = ru; 1605 ret = do_wait(&wo); 1606 1607 if (ret > 0) { 1608 ret = 0; 1609 } else if (infop) { 1610 /* 1611 * For a WNOHANG return, clear out all the fields 1612 * we would set so the user can easily tell the 1613 * difference. 1614 */ 1615 if (!ret) 1616 ret = put_user(0, &infop->si_signo); 1617 if (!ret) 1618 ret = put_user(0, &infop->si_errno); 1619 if (!ret) 1620 ret = put_user(0, &infop->si_code); 1621 if (!ret) 1622 ret = put_user(0, &infop->si_pid); 1623 if (!ret) 1624 ret = put_user(0, &infop->si_uid); 1625 if (!ret) 1626 ret = put_user(0, &infop->si_status); 1627 } 1628 1629 put_pid(pid); 1630 1631 /* avoid REGPARM breakage on x86: */ 1632 asmlinkage_protect(5, ret, which, upid, infop, options, ru); 1633 return ret; 1634 } 1635 1636 SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, 1637 int, options, struct rusage __user *, ru) 1638 { 1639 struct wait_opts wo; 1640 struct pid *pid = NULL; 1641 enum pid_type type; 1642 long ret; 1643 1644 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| 1645 __WNOTHREAD|__WCLONE|__WALL)) 1646 return -EINVAL; 1647 1648 if (upid == -1) 1649 type = PIDTYPE_MAX; 1650 else if (upid < 0) { 1651 type = PIDTYPE_PGID; 1652 pid = find_get_pid(-upid); 1653 } else if (upid == 0) { 1654 type = PIDTYPE_PGID; 1655 pid = get_task_pid(current, PIDTYPE_PGID); 1656 } else /* upid > 0 */ { 1657 type = PIDTYPE_PID; 1658 pid = find_get_pid(upid); 1659 } 1660 1661 wo.wo_type = type; 1662 wo.wo_pid = pid; 1663 wo.wo_flags = options | WEXITED; 1664 wo.wo_info = NULL; 1665 wo.wo_stat = stat_addr; 1666 wo.wo_rusage = ru; 1667 ret = do_wait(&wo); 1668 put_pid(pid); 1669 1670 /* avoid REGPARM breakage on x86: */ 1671 asmlinkage_protect(4, ret, upid, stat_addr, options, ru); 1672 return ret; 1673 } 1674 1675 #ifdef __ARCH_WANT_SYS_WAITPID 1676 1677 /* 1678 * sys_waitpid() remains for compatibility. waitpid() should be 1679 * implemented by calling sys_wait4() from libc.a. 1680 */ 1681 SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) 1682 { 1683 return sys_wait4(pid, stat_addr, options, NULL); 1684 } 1685 1686 #endif 1687