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/freezer.h> 24 #include <linux/binfmts.h> 25 #include <linux/nsproxy.h> 26 #include <linux/pid_namespace.h> 27 #include <linux/ptrace.h> 28 #include <linux/profile.h> 29 #include <linux/mount.h> 30 #include <linux/proc_fs.h> 31 #include <linux/kthread.h> 32 #include <linux/mempolicy.h> 33 #include <linux/taskstats_kern.h> 34 #include <linux/delayacct.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 list_del_rcu(&p->thread_node); 78 } 79 80 /* 81 * This function expects the tasklist_lock write-locked. 82 */ 83 static void __exit_signal(struct task_struct *tsk) 84 { 85 struct signal_struct *sig = tsk->signal; 86 bool group_dead = thread_group_leader(tsk); 87 struct sighand_struct *sighand; 88 struct tty_struct *uninitialized_var(tty); 89 cputime_t utime, stime; 90 91 sighand = rcu_dereference_check(tsk->sighand, 92 lockdep_tasklist_lock_is_held()); 93 spin_lock(&sighand->siglock); 94 95 posix_cpu_timers_exit(tsk); 96 if (group_dead) { 97 posix_cpu_timers_exit_group(tsk); 98 tty = sig->tty; 99 sig->tty = NULL; 100 } else { 101 /* 102 * This can only happen if the caller is de_thread(). 103 * FIXME: this is the temporary hack, we should teach 104 * posix-cpu-timers to handle this case correctly. 105 */ 106 if (unlikely(has_group_leader_pid(tsk))) 107 posix_cpu_timers_exit_group(tsk); 108 109 /* 110 * If there is any task waiting for the group exit 111 * then notify it: 112 */ 113 if (sig->notify_count > 0 && !--sig->notify_count) 114 wake_up_process(sig->group_exit_task); 115 116 if (tsk == sig->curr_target) 117 sig->curr_target = next_thread(tsk); 118 /* 119 * Accumulate here the counters for all threads but the 120 * group leader as they die, so they can be added into 121 * the process-wide totals when those are taken. 122 * The group leader stays around as a zombie as long 123 * as there are other threads. When it gets reaped, 124 * the exit.c code will add its counts into these totals. 125 * We won't ever get here for the group leader, since it 126 * will have been the last reference on the signal_struct. 127 */ 128 task_cputime(tsk, &utime, &stime); 129 sig->utime += utime; 130 sig->stime += stime; 131 sig->gtime += task_gtime(tsk); 132 sig->min_flt += tsk->min_flt; 133 sig->maj_flt += tsk->maj_flt; 134 sig->nvcsw += tsk->nvcsw; 135 sig->nivcsw += tsk->nivcsw; 136 sig->inblock += task_io_get_inblock(tsk); 137 sig->oublock += task_io_get_oublock(tsk); 138 task_io_accounting_add(&sig->ioac, &tsk->ioac); 139 sig->sum_sched_runtime += tsk->se.sum_exec_runtime; 140 } 141 142 sig->nr_threads--; 143 __unhash_process(tsk, group_dead); 144 145 /* 146 * Do this under ->siglock, we can race with another thread 147 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. 148 */ 149 flush_sigqueue(&tsk->pending); 150 tsk->sighand = NULL; 151 spin_unlock(&sighand->siglock); 152 153 __cleanup_sighand(sighand); 154 clear_tsk_thread_flag(tsk,TIF_SIGPENDING); 155 if (group_dead) { 156 flush_sigqueue(&sig->shared_pending); 157 tty_kref_put(tty); 158 } 159 } 160 161 static void delayed_put_task_struct(struct rcu_head *rhp) 162 { 163 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); 164 165 perf_event_delayed_put(tsk); 166 trace_sched_process_free(tsk); 167 put_task_struct(tsk); 168 } 169 170 171 void release_task(struct task_struct * p) 172 { 173 struct task_struct *leader; 174 int zap_leader; 175 repeat: 176 /* don't need to get the RCU readlock here - the process is dead and 177 * can't be modifying its own credentials. But shut RCU-lockdep up */ 178 rcu_read_lock(); 179 atomic_dec(&__task_cred(p)->user->processes); 180 rcu_read_unlock(); 181 182 proc_flush_task(p); 183 184 write_lock_irq(&tasklist_lock); 185 ptrace_release_task(p); 186 __exit_signal(p); 187 188 /* 189 * If we are the last non-leader member of the thread 190 * group, and the leader is zombie, then notify the 191 * group leader's parent process. (if it wants notification.) 192 */ 193 zap_leader = 0; 194 leader = p->group_leader; 195 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) { 196 /* 197 * If we were the last child thread and the leader has 198 * exited already, and the leader's parent ignores SIGCHLD, 199 * then we are the one who should release the leader. 200 */ 201 zap_leader = do_notify_parent(leader, leader->exit_signal); 202 if (zap_leader) 203 leader->exit_state = EXIT_DEAD; 204 } 205 206 write_unlock_irq(&tasklist_lock); 207 release_thread(p); 208 call_rcu(&p->rcu, delayed_put_task_struct); 209 210 p = leader; 211 if (unlikely(zap_leader)) 212 goto repeat; 213 } 214 215 /* 216 * This checks not only the pgrp, but falls back on the pid if no 217 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly 218 * without this... 219 * 220 * The caller must hold rcu lock or the tasklist lock. 221 */ 222 struct pid *session_of_pgrp(struct pid *pgrp) 223 { 224 struct task_struct *p; 225 struct pid *sid = NULL; 226 227 p = pid_task(pgrp, PIDTYPE_PGID); 228 if (p == NULL) 229 p = pid_task(pgrp, PIDTYPE_PID); 230 if (p != NULL) 231 sid = task_session(p); 232 233 return sid; 234 } 235 236 /* 237 * Determine if a process group is "orphaned", according to the POSIX 238 * definition in 2.2.2.52. Orphaned process groups are not to be affected 239 * by terminal-generated stop signals. Newly orphaned process groups are 240 * to receive a SIGHUP and a SIGCONT. 241 * 242 * "I ask you, have you ever known what it is to be an orphan?" 243 */ 244 static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task) 245 { 246 struct task_struct *p; 247 248 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 249 if ((p == ignored_task) || 250 (p->exit_state && thread_group_empty(p)) || 251 is_global_init(p->real_parent)) 252 continue; 253 254 if (task_pgrp(p->real_parent) != pgrp && 255 task_session(p->real_parent) == task_session(p)) 256 return 0; 257 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 258 259 return 1; 260 } 261 262 int is_current_pgrp_orphaned(void) 263 { 264 int retval; 265 266 read_lock(&tasklist_lock); 267 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); 268 read_unlock(&tasklist_lock); 269 270 return retval; 271 } 272 273 static bool has_stopped_jobs(struct pid *pgrp) 274 { 275 struct task_struct *p; 276 277 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 278 if (p->signal->flags & SIGNAL_STOP_STOPPED) 279 return true; 280 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 281 282 return false; 283 } 284 285 /* 286 * Check to see if any process groups have become orphaned as 287 * a result of our exiting, and if they have any stopped jobs, 288 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 289 */ 290 static void 291 kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) 292 { 293 struct pid *pgrp = task_pgrp(tsk); 294 struct task_struct *ignored_task = tsk; 295 296 if (!parent) 297 /* exit: our father is in a different pgrp than 298 * we are and we were the only connection outside. 299 */ 300 parent = tsk->real_parent; 301 else 302 /* reparent: our child is in a different pgrp than 303 * we are, and it was the only connection outside. 304 */ 305 ignored_task = NULL; 306 307 if (task_pgrp(parent) != pgrp && 308 task_session(parent) == task_session(tsk) && 309 will_become_orphaned_pgrp(pgrp, ignored_task) && 310 has_stopped_jobs(pgrp)) { 311 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); 312 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); 313 } 314 } 315 316 /* 317 * Let kernel threads use this to say that they allow a certain signal. 318 * Must not be used if kthread was cloned with CLONE_SIGHAND. 319 */ 320 int allow_signal(int sig) 321 { 322 if (!valid_signal(sig) || sig < 1) 323 return -EINVAL; 324 325 spin_lock_irq(¤t->sighand->siglock); 326 /* This is only needed for daemonize()'ed kthreads */ 327 sigdelset(¤t->blocked, sig); 328 /* 329 * Kernel threads handle their own signals. Let the signal code 330 * know it'll be handled, so that they don't get converted to 331 * SIGKILL or just silently dropped. 332 */ 333 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2; 334 recalc_sigpending(); 335 spin_unlock_irq(¤t->sighand->siglock); 336 return 0; 337 } 338 339 EXPORT_SYMBOL(allow_signal); 340 341 int disallow_signal(int sig) 342 { 343 if (!valid_signal(sig) || sig < 1) 344 return -EINVAL; 345 346 spin_lock_irq(¤t->sighand->siglock); 347 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN; 348 recalc_sigpending(); 349 spin_unlock_irq(¤t->sighand->siglock); 350 return 0; 351 } 352 353 EXPORT_SYMBOL(disallow_signal); 354 355 #ifdef CONFIG_MM_OWNER 356 /* 357 * A task is exiting. If it owned this mm, find a new owner for the mm. 358 */ 359 void mm_update_next_owner(struct mm_struct *mm) 360 { 361 struct task_struct *c, *g, *p = current; 362 363 retry: 364 /* 365 * If the exiting or execing task is not the owner, it's 366 * someone else's problem. 367 */ 368 if (mm->owner != p) 369 return; 370 /* 371 * The current owner is exiting/execing and there are no other 372 * candidates. Do not leave the mm pointing to a possibly 373 * freed task structure. 374 */ 375 if (atomic_read(&mm->mm_users) <= 1) { 376 mm->owner = NULL; 377 return; 378 } 379 380 read_lock(&tasklist_lock); 381 /* 382 * Search in the children 383 */ 384 list_for_each_entry(c, &p->children, sibling) { 385 if (c->mm == mm) 386 goto assign_new_owner; 387 } 388 389 /* 390 * Search in the siblings 391 */ 392 list_for_each_entry(c, &p->real_parent->children, sibling) { 393 if (c->mm == mm) 394 goto assign_new_owner; 395 } 396 397 /* 398 * Search through everything else. We should not get 399 * here often 400 */ 401 do_each_thread(g, c) { 402 if (c->mm == mm) 403 goto assign_new_owner; 404 } while_each_thread(g, c); 405 406 read_unlock(&tasklist_lock); 407 /* 408 * We found no owner yet mm_users > 1: this implies that we are 409 * most likely racing with swapoff (try_to_unuse()) or /proc or 410 * ptrace or page migration (get_task_mm()). Mark owner as NULL. 411 */ 412 mm->owner = NULL; 413 return; 414 415 assign_new_owner: 416 BUG_ON(c == p); 417 get_task_struct(c); 418 /* 419 * The task_lock protects c->mm from changing. 420 * We always want mm->owner->mm == mm 421 */ 422 task_lock(c); 423 /* 424 * Delay read_unlock() till we have the task_lock() 425 * to ensure that c does not slip away underneath us 426 */ 427 read_unlock(&tasklist_lock); 428 if (c->mm != mm) { 429 task_unlock(c); 430 put_task_struct(c); 431 goto retry; 432 } 433 mm->owner = c; 434 task_unlock(c); 435 put_task_struct(c); 436 } 437 #endif /* CONFIG_MM_OWNER */ 438 439 /* 440 * Turn us into a lazy TLB process if we 441 * aren't already.. 442 */ 443 static void exit_mm(struct task_struct * tsk) 444 { 445 struct mm_struct *mm = tsk->mm; 446 struct core_state *core_state; 447 448 mm_release(tsk, mm); 449 if (!mm) 450 return; 451 sync_mm_rss(mm); 452 /* 453 * Serialize with any possible pending coredump. 454 * We must hold mmap_sem around checking core_state 455 * and clearing tsk->mm. The core-inducing thread 456 * will increment ->nr_threads for each thread in the 457 * group with ->mm != NULL. 458 */ 459 down_read(&mm->mmap_sem); 460 core_state = mm->core_state; 461 if (core_state) { 462 struct core_thread self; 463 up_read(&mm->mmap_sem); 464 465 self.task = tsk; 466 self.next = xchg(&core_state->dumper.next, &self); 467 /* 468 * Implies mb(), the result of xchg() must be visible 469 * to core_state->dumper. 470 */ 471 if (atomic_dec_and_test(&core_state->nr_threads)) 472 complete(&core_state->startup); 473 474 for (;;) { 475 set_task_state(tsk, TASK_UNINTERRUPTIBLE); 476 if (!self.task) /* see coredump_finish() */ 477 break; 478 freezable_schedule(); 479 } 480 __set_task_state(tsk, TASK_RUNNING); 481 down_read(&mm->mmap_sem); 482 } 483 atomic_inc(&mm->mm_count); 484 BUG_ON(mm != tsk->active_mm); 485 /* more a memory barrier than a real lock */ 486 task_lock(tsk); 487 tsk->mm = NULL; 488 up_read(&mm->mmap_sem); 489 enter_lazy_tlb(mm, current); 490 task_unlock(tsk); 491 mm_update_next_owner(mm); 492 mmput(mm); 493 } 494 495 /* 496 * When we die, we re-parent all our children, and try to: 497 * 1. give them to another thread in our thread group, if such a member exists 498 * 2. give it to the first ancestor process which prctl'd itself as a 499 * child_subreaper for its children (like a service manager) 500 * 3. give it to the init process (PID 1) in our pid namespace 501 */ 502 static struct task_struct *find_new_reaper(struct task_struct *father) 503 __releases(&tasklist_lock) 504 __acquires(&tasklist_lock) 505 { 506 struct pid_namespace *pid_ns = task_active_pid_ns(father); 507 struct task_struct *thread; 508 509 thread = father; 510 while_each_thread(father, thread) { 511 if (thread->flags & PF_EXITING) 512 continue; 513 if (unlikely(pid_ns->child_reaper == father)) 514 pid_ns->child_reaper = thread; 515 return thread; 516 } 517 518 if (unlikely(pid_ns->child_reaper == father)) { 519 write_unlock_irq(&tasklist_lock); 520 if (unlikely(pid_ns == &init_pid_ns)) { 521 panic("Attempted to kill init! exitcode=0x%08x\n", 522 father->signal->group_exit_code ?: 523 father->exit_code); 524 } 525 526 zap_pid_ns_processes(pid_ns); 527 write_lock_irq(&tasklist_lock); 528 } else if (father->signal->has_child_subreaper) { 529 struct task_struct *reaper; 530 531 /* 532 * Find the first ancestor marked as child_subreaper. 533 * Note that the code below checks same_thread_group(reaper, 534 * pid_ns->child_reaper). This is what we need to DTRT in a 535 * PID namespace. However we still need the check above, see 536 * http://marc.info/?l=linux-kernel&m=131385460420380 537 */ 538 for (reaper = father->real_parent; 539 reaper != &init_task; 540 reaper = reaper->real_parent) { 541 if (same_thread_group(reaper, pid_ns->child_reaper)) 542 break; 543 if (!reaper->signal->is_child_subreaper) 544 continue; 545 thread = reaper; 546 do { 547 if (!(thread->flags & PF_EXITING)) 548 return reaper; 549 } while_each_thread(reaper, thread); 550 } 551 } 552 553 return pid_ns->child_reaper; 554 } 555 556 /* 557 * Any that need to be release_task'd are put on the @dead list. 558 */ 559 static void reparent_leader(struct task_struct *father, struct task_struct *p, 560 struct list_head *dead) 561 { 562 list_move_tail(&p->sibling, &p->real_parent->children); 563 564 if (p->exit_state == EXIT_DEAD) 565 return; 566 /* 567 * If this is a threaded reparent there is no need to 568 * notify anyone anything has happened. 569 */ 570 if (same_thread_group(p->real_parent, father)) 571 return; 572 573 /* We don't want people slaying init. */ 574 p->exit_signal = SIGCHLD; 575 576 /* If it has exited notify the new parent about this child's death. */ 577 if (!p->ptrace && 578 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { 579 if (do_notify_parent(p, p->exit_signal)) { 580 p->exit_state = EXIT_DEAD; 581 list_move_tail(&p->sibling, dead); 582 } 583 } 584 585 kill_orphaned_pgrp(p, father); 586 } 587 588 static void forget_original_parent(struct task_struct *father) 589 { 590 struct task_struct *p, *n, *reaper; 591 LIST_HEAD(dead_children); 592 593 write_lock_irq(&tasklist_lock); 594 /* 595 * Note that exit_ptrace() and find_new_reaper() might 596 * drop tasklist_lock and reacquire it. 597 */ 598 exit_ptrace(father); 599 reaper = find_new_reaper(father); 600 601 list_for_each_entry_safe(p, n, &father->children, sibling) { 602 struct task_struct *t = p; 603 do { 604 t->real_parent = reaper; 605 if (t->parent == father) { 606 BUG_ON(t->ptrace); 607 t->parent = t->real_parent; 608 } 609 if (t->pdeath_signal) 610 group_send_sig_info(t->pdeath_signal, 611 SEND_SIG_NOINFO, t); 612 } while_each_thread(p, t); 613 reparent_leader(father, p, &dead_children); 614 } 615 write_unlock_irq(&tasklist_lock); 616 617 BUG_ON(!list_empty(&father->children)); 618 619 list_for_each_entry_safe(p, n, &dead_children, sibling) { 620 list_del_init(&p->sibling); 621 release_task(p); 622 } 623 } 624 625 /* 626 * Send signals to all our closest relatives so that they know 627 * to properly mourn us.. 628 */ 629 static void exit_notify(struct task_struct *tsk, int group_dead) 630 { 631 bool autoreap; 632 633 /* 634 * This does two things: 635 * 636 * A. Make init inherit all the child processes 637 * B. Check to see if any process groups have become orphaned 638 * as a result of our exiting, and if they have any stopped 639 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 640 */ 641 forget_original_parent(tsk); 642 643 write_lock_irq(&tasklist_lock); 644 if (group_dead) 645 kill_orphaned_pgrp(tsk->group_leader, NULL); 646 647 if (unlikely(tsk->ptrace)) { 648 int sig = thread_group_leader(tsk) && 649 thread_group_empty(tsk) && 650 !ptrace_reparented(tsk) ? 651 tsk->exit_signal : SIGCHLD; 652 autoreap = do_notify_parent(tsk, sig); 653 } else if (thread_group_leader(tsk)) { 654 autoreap = thread_group_empty(tsk) && 655 do_notify_parent(tsk, tsk->exit_signal); 656 } else { 657 autoreap = true; 658 } 659 660 tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE; 661 662 /* mt-exec, de_thread() is waiting for group leader */ 663 if (unlikely(tsk->signal->notify_count < 0)) 664 wake_up_process(tsk->signal->group_exit_task); 665 write_unlock_irq(&tasklist_lock); 666 667 /* If the process is dead, release it - nobody will wait for it */ 668 if (autoreap) 669 release_task(tsk); 670 } 671 672 #ifdef CONFIG_DEBUG_STACK_USAGE 673 static void check_stack_usage(void) 674 { 675 static DEFINE_SPINLOCK(low_water_lock); 676 static int lowest_to_date = THREAD_SIZE; 677 unsigned long free; 678 679 free = stack_not_used(current); 680 681 if (free >= lowest_to_date) 682 return; 683 684 spin_lock(&low_water_lock); 685 if (free < lowest_to_date) { 686 printk(KERN_WARNING "%s (%d) used greatest stack depth: " 687 "%lu bytes left\n", 688 current->comm, task_pid_nr(current), free); 689 lowest_to_date = free; 690 } 691 spin_unlock(&low_water_lock); 692 } 693 #else 694 static inline void check_stack_usage(void) {} 695 #endif 696 697 void do_exit(long code) 698 { 699 struct task_struct *tsk = current; 700 int group_dead; 701 702 profile_task_exit(tsk); 703 704 WARN_ON(blk_needs_flush_plug(tsk)); 705 706 if (unlikely(in_interrupt())) 707 panic("Aiee, killing interrupt handler!"); 708 if (unlikely(!tsk->pid)) 709 panic("Attempted to kill the idle task!"); 710 711 /* 712 * If do_exit is called because this processes oopsed, it's possible 713 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before 714 * continuing. Amongst other possible reasons, this is to prevent 715 * mm_release()->clear_child_tid() from writing to a user-controlled 716 * kernel address. 717 */ 718 set_fs(USER_DS); 719 720 ptrace_event(PTRACE_EVENT_EXIT, code); 721 722 validate_creds_for_do_exit(tsk); 723 724 /* 725 * We're taking recursive faults here in do_exit. Safest is to just 726 * leave this task alone and wait for reboot. 727 */ 728 if (unlikely(tsk->flags & PF_EXITING)) { 729 printk(KERN_ALERT 730 "Fixing recursive fault but reboot is needed!\n"); 731 /* 732 * We can do this unlocked here. The futex code uses 733 * this flag just to verify whether the pi state 734 * cleanup has been done or not. In the worst case it 735 * loops once more. We pretend that the cleanup was 736 * done as there is no way to return. Either the 737 * OWNER_DIED bit is set by now or we push the blocked 738 * task into the wait for ever nirwana as well. 739 */ 740 tsk->flags |= PF_EXITPIDONE; 741 set_current_state(TASK_UNINTERRUPTIBLE); 742 schedule(); 743 } 744 745 exit_signals(tsk); /* sets PF_EXITING */ 746 /* 747 * tsk->flags are checked in the futex code to protect against 748 * an exiting task cleaning up the robust pi futexes. 749 */ 750 smp_mb(); 751 raw_spin_unlock_wait(&tsk->pi_lock); 752 753 if (unlikely(in_atomic())) 754 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n", 755 current->comm, task_pid_nr(current), 756 preempt_count()); 757 758 acct_update_integrals(tsk); 759 /* sync mm's RSS info before statistics gathering */ 760 if (tsk->mm) 761 sync_mm_rss(tsk->mm); 762 group_dead = atomic_dec_and_test(&tsk->signal->live); 763 if (group_dead) { 764 hrtimer_cancel(&tsk->signal->real_timer); 765 exit_itimers(tsk->signal); 766 if (tsk->mm) 767 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); 768 } 769 acct_collect(code, group_dead); 770 if (group_dead) 771 tty_audit_exit(); 772 audit_free(tsk); 773 774 tsk->exit_code = code; 775 taskstats_exit(tsk, group_dead); 776 777 exit_mm(tsk); 778 779 if (group_dead) 780 acct_process(); 781 trace_sched_process_exit(tsk); 782 783 exit_sem(tsk); 784 exit_shm(tsk); 785 exit_files(tsk); 786 exit_fs(tsk); 787 if (group_dead) 788 disassociate_ctty(1); 789 exit_task_namespaces(tsk); 790 exit_task_work(tsk); 791 exit_thread(); 792 793 /* 794 * Flush inherited counters to the parent - before the parent 795 * gets woken up by child-exit notifications. 796 * 797 * because of cgroup mode, must be called before cgroup_exit() 798 */ 799 perf_event_exit_task(tsk); 800 801 cgroup_exit(tsk); 802 803 module_put(task_thread_info(tsk)->exec_domain->module); 804 805 /* 806 * FIXME: do that only when needed, using sched_exit tracepoint 807 */ 808 flush_ptrace_hw_breakpoint(tsk); 809 810 exit_notify(tsk, group_dead); 811 proc_exit_connector(tsk); 812 #ifdef CONFIG_NUMA 813 task_lock(tsk); 814 mpol_put(tsk->mempolicy); 815 tsk->mempolicy = NULL; 816 task_unlock(tsk); 817 #endif 818 #ifdef CONFIG_FUTEX 819 if (unlikely(current->pi_state_cache)) 820 kfree(current->pi_state_cache); 821 #endif 822 /* 823 * Make sure we are holding no locks: 824 */ 825 debug_check_no_locks_held(); 826 /* 827 * We can do this unlocked here. The futex code uses this flag 828 * just to verify whether the pi state cleanup has been done 829 * or not. In the worst case it loops once more. 830 */ 831 tsk->flags |= PF_EXITPIDONE; 832 833 if (tsk->io_context) 834 exit_io_context(tsk); 835 836 if (tsk->splice_pipe) 837 free_pipe_info(tsk->splice_pipe); 838 839 if (tsk->task_frag.page) 840 put_page(tsk->task_frag.page); 841 842 validate_creds_for_do_exit(tsk); 843 844 check_stack_usage(); 845 preempt_disable(); 846 if (tsk->nr_dirtied) 847 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); 848 exit_rcu(); 849 850 /* 851 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed 852 * when the following two conditions become true. 853 * - There is race condition of mmap_sem (It is acquired by 854 * exit_mm()), and 855 * - SMI occurs before setting TASK_RUNINNG. 856 * (or hypervisor of virtual machine switches to other guest) 857 * As a result, we may become TASK_RUNNING after becoming TASK_DEAD 858 * 859 * To avoid it, we have to wait for releasing tsk->pi_lock which 860 * is held by try_to_wake_up() 861 */ 862 smp_mb(); 863 raw_spin_unlock_wait(&tsk->pi_lock); 864 865 /* causes final put_task_struct in finish_task_switch(). */ 866 tsk->state = TASK_DEAD; 867 tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */ 868 schedule(); 869 BUG(); 870 /* Avoid "noreturn function does return". */ 871 for (;;) 872 cpu_relax(); /* For when BUG is null */ 873 } 874 875 EXPORT_SYMBOL_GPL(do_exit); 876 877 void complete_and_exit(struct completion *comp, long code) 878 { 879 if (comp) 880 complete(comp); 881 882 do_exit(code); 883 } 884 885 EXPORT_SYMBOL(complete_and_exit); 886 887 SYSCALL_DEFINE1(exit, int, error_code) 888 { 889 do_exit((error_code&0xff)<<8); 890 } 891 892 /* 893 * Take down every thread in the group. This is called by fatal signals 894 * as well as by sys_exit_group (below). 895 */ 896 void 897 do_group_exit(int exit_code) 898 { 899 struct signal_struct *sig = current->signal; 900 901 BUG_ON(exit_code & 0x80); /* core dumps don't get here */ 902 903 if (signal_group_exit(sig)) 904 exit_code = sig->group_exit_code; 905 else if (!thread_group_empty(current)) { 906 struct sighand_struct *const sighand = current->sighand; 907 spin_lock_irq(&sighand->siglock); 908 if (signal_group_exit(sig)) 909 /* Another thread got here before we took the lock. */ 910 exit_code = sig->group_exit_code; 911 else { 912 sig->group_exit_code = exit_code; 913 sig->flags = SIGNAL_GROUP_EXIT; 914 zap_other_threads(current); 915 } 916 spin_unlock_irq(&sighand->siglock); 917 } 918 919 do_exit(exit_code); 920 /* NOTREACHED */ 921 } 922 923 /* 924 * this kills every thread in the thread group. Note that any externally 925 * wait4()-ing process will get the correct exit code - even if this 926 * thread is not the thread group leader. 927 */ 928 SYSCALL_DEFINE1(exit_group, int, error_code) 929 { 930 do_group_exit((error_code & 0xff) << 8); 931 /* NOTREACHED */ 932 return 0; 933 } 934 935 struct wait_opts { 936 enum pid_type wo_type; 937 int wo_flags; 938 struct pid *wo_pid; 939 940 struct siginfo __user *wo_info; 941 int __user *wo_stat; 942 struct rusage __user *wo_rusage; 943 944 wait_queue_t child_wait; 945 int notask_error; 946 }; 947 948 static inline 949 struct pid *task_pid_type(struct task_struct *task, enum pid_type type) 950 { 951 if (type != PIDTYPE_PID) 952 task = task->group_leader; 953 return task->pids[type].pid; 954 } 955 956 static int eligible_pid(struct wait_opts *wo, struct task_struct *p) 957 { 958 return wo->wo_type == PIDTYPE_MAX || 959 task_pid_type(p, wo->wo_type) == wo->wo_pid; 960 } 961 962 static int eligible_child(struct wait_opts *wo, struct task_struct *p) 963 { 964 if (!eligible_pid(wo, p)) 965 return 0; 966 /* Wait for all children (clone and not) if __WALL is set; 967 * otherwise, wait for clone children *only* if __WCLONE is 968 * set; otherwise, wait for non-clone children *only*. (Note: 969 * A "clone" child here is one that reports to its parent 970 * using a signal other than SIGCHLD.) */ 971 if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) 972 && !(wo->wo_flags & __WALL)) 973 return 0; 974 975 return 1; 976 } 977 978 static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p, 979 pid_t pid, uid_t uid, int why, int status) 980 { 981 struct siginfo __user *infop; 982 int retval = wo->wo_rusage 983 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; 984 985 put_task_struct(p); 986 infop = wo->wo_info; 987 if (infop) { 988 if (!retval) 989 retval = put_user(SIGCHLD, &infop->si_signo); 990 if (!retval) 991 retval = put_user(0, &infop->si_errno); 992 if (!retval) 993 retval = put_user((short)why, &infop->si_code); 994 if (!retval) 995 retval = put_user(pid, &infop->si_pid); 996 if (!retval) 997 retval = put_user(uid, &infop->si_uid); 998 if (!retval) 999 retval = put_user(status, &infop->si_status); 1000 } 1001 if (!retval) 1002 retval = pid; 1003 return retval; 1004 } 1005 1006 /* 1007 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold 1008 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1009 * the lock and this task is uninteresting. If we return nonzero, we have 1010 * released the lock and the system call should return. 1011 */ 1012 static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) 1013 { 1014 unsigned long state; 1015 int retval, status, traced; 1016 pid_t pid = task_pid_vnr(p); 1017 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1018 struct siginfo __user *infop; 1019 1020 if (!likely(wo->wo_flags & WEXITED)) 1021 return 0; 1022 1023 if (unlikely(wo->wo_flags & WNOWAIT)) { 1024 int exit_code = p->exit_code; 1025 int why; 1026 1027 get_task_struct(p); 1028 read_unlock(&tasklist_lock); 1029 if ((exit_code & 0x7f) == 0) { 1030 why = CLD_EXITED; 1031 status = exit_code >> 8; 1032 } else { 1033 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED; 1034 status = exit_code & 0x7f; 1035 } 1036 return wait_noreap_copyout(wo, p, pid, uid, why, status); 1037 } 1038 1039 traced = ptrace_reparented(p); 1040 /* 1041 * Move the task's state to DEAD/TRACE, only one thread can do this. 1042 */ 1043 state = traced && thread_group_leader(p) ? EXIT_TRACE : EXIT_DEAD; 1044 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) 1045 return 0; 1046 /* 1047 * It can be ptraced but not reparented, check 1048 * thread_group_leader() to filter out sub-threads. 1049 */ 1050 if (likely(!traced) && thread_group_leader(p)) { 1051 struct signal_struct *psig; 1052 struct signal_struct *sig; 1053 unsigned long maxrss; 1054 cputime_t tgutime, tgstime; 1055 1056 /* 1057 * The resource counters for the group leader are in its 1058 * own task_struct. Those for dead threads in the group 1059 * are in its signal_struct, as are those for the child 1060 * processes it has previously reaped. All these 1061 * accumulate in the parent's signal_struct c* fields. 1062 * 1063 * We don't bother to take a lock here to protect these 1064 * p->signal fields, because they are only touched by 1065 * __exit_signal, which runs with tasklist_lock 1066 * write-locked anyway, and so is excluded here. We do 1067 * need to protect the access to parent->signal fields, 1068 * as other threads in the parent group can be right 1069 * here reaping other children at the same time. 1070 * 1071 * We use thread_group_cputime_adjusted() to get times for the thread 1072 * group, which consolidates times for all threads in the 1073 * group including the group leader. 1074 */ 1075 thread_group_cputime_adjusted(p, &tgutime, &tgstime); 1076 spin_lock_irq(&p->real_parent->sighand->siglock); 1077 psig = p->real_parent->signal; 1078 sig = p->signal; 1079 psig->cutime += tgutime + sig->cutime; 1080 psig->cstime += tgstime + sig->cstime; 1081 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime; 1082 psig->cmin_flt += 1083 p->min_flt + sig->min_flt + sig->cmin_flt; 1084 psig->cmaj_flt += 1085 p->maj_flt + sig->maj_flt + sig->cmaj_flt; 1086 psig->cnvcsw += 1087 p->nvcsw + sig->nvcsw + sig->cnvcsw; 1088 psig->cnivcsw += 1089 p->nivcsw + sig->nivcsw + sig->cnivcsw; 1090 psig->cinblock += 1091 task_io_get_inblock(p) + 1092 sig->inblock + sig->cinblock; 1093 psig->coublock += 1094 task_io_get_oublock(p) + 1095 sig->oublock + sig->coublock; 1096 maxrss = max(sig->maxrss, sig->cmaxrss); 1097 if (psig->cmaxrss < maxrss) 1098 psig->cmaxrss = maxrss; 1099 task_io_accounting_add(&psig->ioac, &p->ioac); 1100 task_io_accounting_add(&psig->ioac, &sig->ioac); 1101 spin_unlock_irq(&p->real_parent->sighand->siglock); 1102 } 1103 1104 /* 1105 * Now we are sure this task is interesting, and no other 1106 * thread can reap it because we its state == DEAD/TRACE. 1107 */ 1108 read_unlock(&tasklist_lock); 1109 1110 retval = wo->wo_rusage 1111 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; 1112 status = (p->signal->flags & SIGNAL_GROUP_EXIT) 1113 ? p->signal->group_exit_code : p->exit_code; 1114 if (!retval && wo->wo_stat) 1115 retval = put_user(status, wo->wo_stat); 1116 1117 infop = wo->wo_info; 1118 if (!retval && infop) 1119 retval = put_user(SIGCHLD, &infop->si_signo); 1120 if (!retval && infop) 1121 retval = put_user(0, &infop->si_errno); 1122 if (!retval && infop) { 1123 int why; 1124 1125 if ((status & 0x7f) == 0) { 1126 why = CLD_EXITED; 1127 status >>= 8; 1128 } else { 1129 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; 1130 status &= 0x7f; 1131 } 1132 retval = put_user((short)why, &infop->si_code); 1133 if (!retval) 1134 retval = put_user(status, &infop->si_status); 1135 } 1136 if (!retval && infop) 1137 retval = put_user(pid, &infop->si_pid); 1138 if (!retval && infop) 1139 retval = put_user(uid, &infop->si_uid); 1140 if (!retval) 1141 retval = pid; 1142 1143 if (state == EXIT_TRACE) { 1144 write_lock_irq(&tasklist_lock); 1145 /* We dropped tasklist, ptracer could die and untrace */ 1146 ptrace_unlink(p); 1147 1148 /* If parent wants a zombie, don't release it now */ 1149 state = EXIT_ZOMBIE; 1150 if (do_notify_parent(p, p->exit_signal)) 1151 state = EXIT_DEAD; 1152 p->exit_state = state; 1153 write_unlock_irq(&tasklist_lock); 1154 } 1155 if (state == EXIT_DEAD) 1156 release_task(p); 1157 1158 return retval; 1159 } 1160 1161 static int *task_stopped_code(struct task_struct *p, bool ptrace) 1162 { 1163 if (ptrace) { 1164 if (task_is_stopped_or_traced(p) && 1165 !(p->jobctl & JOBCTL_LISTENING)) 1166 return &p->exit_code; 1167 } else { 1168 if (p->signal->flags & SIGNAL_STOP_STOPPED) 1169 return &p->signal->group_exit_code; 1170 } 1171 return NULL; 1172 } 1173 1174 /** 1175 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED 1176 * @wo: wait options 1177 * @ptrace: is the wait for ptrace 1178 * @p: task to wait for 1179 * 1180 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED. 1181 * 1182 * CONTEXT: 1183 * read_lock(&tasklist_lock), which is released if return value is 1184 * non-zero. Also, grabs and releases @p->sighand->siglock. 1185 * 1186 * RETURNS: 1187 * 0 if wait condition didn't exist and search for other wait conditions 1188 * should continue. Non-zero return, -errno on failure and @p's pid on 1189 * success, implies that tasklist_lock is released and wait condition 1190 * search should terminate. 1191 */ 1192 static int wait_task_stopped(struct wait_opts *wo, 1193 int ptrace, struct task_struct *p) 1194 { 1195 struct siginfo __user *infop; 1196 int retval, exit_code, *p_code, why; 1197 uid_t uid = 0; /* unneeded, required by compiler */ 1198 pid_t pid; 1199 1200 /* 1201 * Traditionally we see ptrace'd stopped tasks regardless of options. 1202 */ 1203 if (!ptrace && !(wo->wo_flags & WUNTRACED)) 1204 return 0; 1205 1206 if (!task_stopped_code(p, ptrace)) 1207 return 0; 1208 1209 exit_code = 0; 1210 spin_lock_irq(&p->sighand->siglock); 1211 1212 p_code = task_stopped_code(p, ptrace); 1213 if (unlikely(!p_code)) 1214 goto unlock_sig; 1215 1216 exit_code = *p_code; 1217 if (!exit_code) 1218 goto unlock_sig; 1219 1220 if (!unlikely(wo->wo_flags & WNOWAIT)) 1221 *p_code = 0; 1222 1223 uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1224 unlock_sig: 1225 spin_unlock_irq(&p->sighand->siglock); 1226 if (!exit_code) 1227 return 0; 1228 1229 /* 1230 * Now we are pretty sure this task is interesting. 1231 * Make sure it doesn't get reaped out from under us while we 1232 * give up the lock and then examine it below. We don't want to 1233 * keep holding onto the tasklist_lock while we call getrusage and 1234 * possibly take page faults for user memory. 1235 */ 1236 get_task_struct(p); 1237 pid = task_pid_vnr(p); 1238 why = ptrace ? CLD_TRAPPED : CLD_STOPPED; 1239 read_unlock(&tasklist_lock); 1240 1241 if (unlikely(wo->wo_flags & WNOWAIT)) 1242 return wait_noreap_copyout(wo, p, pid, uid, why, exit_code); 1243 1244 retval = wo->wo_rusage 1245 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; 1246 if (!retval && wo->wo_stat) 1247 retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat); 1248 1249 infop = wo->wo_info; 1250 if (!retval && infop) 1251 retval = put_user(SIGCHLD, &infop->si_signo); 1252 if (!retval && infop) 1253 retval = put_user(0, &infop->si_errno); 1254 if (!retval && infop) 1255 retval = put_user((short)why, &infop->si_code); 1256 if (!retval && infop) 1257 retval = put_user(exit_code, &infop->si_status); 1258 if (!retval && infop) 1259 retval = put_user(pid, &infop->si_pid); 1260 if (!retval && infop) 1261 retval = put_user(uid, &infop->si_uid); 1262 if (!retval) 1263 retval = pid; 1264 put_task_struct(p); 1265 1266 BUG_ON(!retval); 1267 return retval; 1268 } 1269 1270 /* 1271 * Handle do_wait work for one task in a live, non-stopped state. 1272 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1273 * the lock and this task is uninteresting. If we return nonzero, we have 1274 * released the lock and the system call should return. 1275 */ 1276 static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) 1277 { 1278 int retval; 1279 pid_t pid; 1280 uid_t uid; 1281 1282 if (!unlikely(wo->wo_flags & WCONTINUED)) 1283 return 0; 1284 1285 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) 1286 return 0; 1287 1288 spin_lock_irq(&p->sighand->siglock); 1289 /* Re-check with the lock held. */ 1290 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { 1291 spin_unlock_irq(&p->sighand->siglock); 1292 return 0; 1293 } 1294 if (!unlikely(wo->wo_flags & WNOWAIT)) 1295 p->signal->flags &= ~SIGNAL_STOP_CONTINUED; 1296 uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1297 spin_unlock_irq(&p->sighand->siglock); 1298 1299 pid = task_pid_vnr(p); 1300 get_task_struct(p); 1301 read_unlock(&tasklist_lock); 1302 1303 if (!wo->wo_info) { 1304 retval = wo->wo_rusage 1305 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; 1306 put_task_struct(p); 1307 if (!retval && wo->wo_stat) 1308 retval = put_user(0xffff, wo->wo_stat); 1309 if (!retval) 1310 retval = pid; 1311 } else { 1312 retval = wait_noreap_copyout(wo, p, pid, uid, 1313 CLD_CONTINUED, SIGCONT); 1314 BUG_ON(retval == 0); 1315 } 1316 1317 return retval; 1318 } 1319 1320 /* 1321 * Consider @p for a wait by @parent. 1322 * 1323 * -ECHILD should be in ->notask_error before the first call. 1324 * Returns nonzero for a final return, when we have unlocked tasklist_lock. 1325 * Returns zero if the search for a child should continue; 1326 * then ->notask_error is 0 if @p is an eligible child, 1327 * or another error from security_task_wait(), or still -ECHILD. 1328 */ 1329 static int wait_consider_task(struct wait_opts *wo, int ptrace, 1330 struct task_struct *p) 1331 { 1332 int ret; 1333 1334 if (unlikely(p->exit_state == EXIT_DEAD)) 1335 return 0; 1336 1337 ret = eligible_child(wo, p); 1338 if (!ret) 1339 return ret; 1340 1341 ret = security_task_wait(p); 1342 if (unlikely(ret < 0)) { 1343 /* 1344 * If we have not yet seen any eligible child, 1345 * then let this error code replace -ECHILD. 1346 * A permission error will give the user a clue 1347 * to look for security policy problems, rather 1348 * than for mysterious wait bugs. 1349 */ 1350 if (wo->notask_error) 1351 wo->notask_error = ret; 1352 return 0; 1353 } 1354 1355 if (unlikely(p->exit_state == EXIT_TRACE)) { 1356 /* 1357 * ptrace == 0 means we are the natural parent. In this case 1358 * we should clear notask_error, debugger will notify us. 1359 */ 1360 if (likely(!ptrace)) 1361 wo->notask_error = 0; 1362 return 0; 1363 } 1364 1365 if (likely(!ptrace) && unlikely(p->ptrace)) { 1366 /* 1367 * If it is traced by its real parent's group, just pretend 1368 * the caller is ptrace_do_wait() and reap this child if it 1369 * is zombie. 1370 * 1371 * This also hides group stop state from real parent; otherwise 1372 * a single stop can be reported twice as group and ptrace stop. 1373 * If a ptracer wants to distinguish these two events for its 1374 * own children it should create a separate process which takes 1375 * the role of real parent. 1376 */ 1377 if (!ptrace_reparented(p)) 1378 ptrace = 1; 1379 } 1380 1381 /* slay zombie? */ 1382 if (p->exit_state == EXIT_ZOMBIE) { 1383 /* we don't reap group leaders with subthreads */ 1384 if (!delay_group_leader(p)) { 1385 /* 1386 * A zombie ptracee is only visible to its ptracer. 1387 * Notification and reaping will be cascaded to the 1388 * real parent when the ptracer detaches. 1389 */ 1390 if (unlikely(ptrace) || likely(!p->ptrace)) 1391 return wait_task_zombie(wo, p); 1392 } 1393 1394 /* 1395 * Allow access to stopped/continued state via zombie by 1396 * falling through. Clearing of notask_error is complex. 1397 * 1398 * When !@ptrace: 1399 * 1400 * If WEXITED is set, notask_error should naturally be 1401 * cleared. If not, subset of WSTOPPED|WCONTINUED is set, 1402 * so, if there are live subthreads, there are events to 1403 * wait for. If all subthreads are dead, it's still safe 1404 * to clear - this function will be called again in finite 1405 * amount time once all the subthreads are released and 1406 * will then return without clearing. 1407 * 1408 * When @ptrace: 1409 * 1410 * Stopped state is per-task and thus can't change once the 1411 * target task dies. Only continued and exited can happen. 1412 * Clear notask_error if WCONTINUED | WEXITED. 1413 */ 1414 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED))) 1415 wo->notask_error = 0; 1416 } else { 1417 /* 1418 * @p is alive and it's gonna stop, continue or exit, so 1419 * there always is something to wait for. 1420 */ 1421 wo->notask_error = 0; 1422 } 1423 1424 /* 1425 * Wait for stopped. Depending on @ptrace, different stopped state 1426 * is used and the two don't interact with each other. 1427 */ 1428 ret = wait_task_stopped(wo, ptrace, p); 1429 if (ret) 1430 return ret; 1431 1432 /* 1433 * Wait for continued. There's only one continued state and the 1434 * ptracer can consume it which can confuse the real parent. Don't 1435 * use WCONTINUED from ptracer. You don't need or want it. 1436 */ 1437 return wait_task_continued(wo, p); 1438 } 1439 1440 /* 1441 * Do the work of do_wait() for one thread in the group, @tsk. 1442 * 1443 * -ECHILD should be in ->notask_error before the first call. 1444 * Returns nonzero for a final return, when we have unlocked tasklist_lock. 1445 * Returns zero if the search for a child should continue; then 1446 * ->notask_error is 0 if there were any eligible children, 1447 * or another error from security_task_wait(), or still -ECHILD. 1448 */ 1449 static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) 1450 { 1451 struct task_struct *p; 1452 1453 list_for_each_entry(p, &tsk->children, sibling) { 1454 int ret = wait_consider_task(wo, 0, p); 1455 if (ret) 1456 return ret; 1457 } 1458 1459 return 0; 1460 } 1461 1462 static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) 1463 { 1464 struct task_struct *p; 1465 1466 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { 1467 int ret = wait_consider_task(wo, 1, p); 1468 if (ret) 1469 return ret; 1470 } 1471 1472 return 0; 1473 } 1474 1475 static int child_wait_callback(wait_queue_t *wait, unsigned mode, 1476 int sync, void *key) 1477 { 1478 struct wait_opts *wo = container_of(wait, struct wait_opts, 1479 child_wait); 1480 struct task_struct *p = key; 1481 1482 if (!eligible_pid(wo, p)) 1483 return 0; 1484 1485 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) 1486 return 0; 1487 1488 return default_wake_function(wait, mode, sync, key); 1489 } 1490 1491 void __wake_up_parent(struct task_struct *p, struct task_struct *parent) 1492 { 1493 __wake_up_sync_key(&parent->signal->wait_chldexit, 1494 TASK_INTERRUPTIBLE, 1, p); 1495 } 1496 1497 static long do_wait(struct wait_opts *wo) 1498 { 1499 struct task_struct *tsk; 1500 int retval; 1501 1502 trace_sched_process_wait(wo->wo_pid); 1503 1504 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); 1505 wo->child_wait.private = current; 1506 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); 1507 repeat: 1508 /* 1509 * If there is nothing that can match our critiera just get out. 1510 * We will clear ->notask_error to zero if we see any child that 1511 * might later match our criteria, even if we are not able to reap 1512 * it yet. 1513 */ 1514 wo->notask_error = -ECHILD; 1515 if ((wo->wo_type < PIDTYPE_MAX) && 1516 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type]))) 1517 goto notask; 1518 1519 set_current_state(TASK_INTERRUPTIBLE); 1520 read_lock(&tasklist_lock); 1521 tsk = current; 1522 do { 1523 retval = do_wait_thread(wo, tsk); 1524 if (retval) 1525 goto end; 1526 1527 retval = ptrace_do_wait(wo, tsk); 1528 if (retval) 1529 goto end; 1530 1531 if (wo->wo_flags & __WNOTHREAD) 1532 break; 1533 } while_each_thread(current, tsk); 1534 read_unlock(&tasklist_lock); 1535 1536 notask: 1537 retval = wo->notask_error; 1538 if (!retval && !(wo->wo_flags & WNOHANG)) { 1539 retval = -ERESTARTSYS; 1540 if (!signal_pending(current)) { 1541 schedule(); 1542 goto repeat; 1543 } 1544 } 1545 end: 1546 __set_current_state(TASK_RUNNING); 1547 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); 1548 return retval; 1549 } 1550 1551 SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, 1552 infop, int, options, struct rusage __user *, ru) 1553 { 1554 struct wait_opts wo; 1555 struct pid *pid = NULL; 1556 enum pid_type type; 1557 long ret; 1558 1559 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED)) 1560 return -EINVAL; 1561 if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) 1562 return -EINVAL; 1563 1564 switch (which) { 1565 case P_ALL: 1566 type = PIDTYPE_MAX; 1567 break; 1568 case P_PID: 1569 type = PIDTYPE_PID; 1570 if (upid <= 0) 1571 return -EINVAL; 1572 break; 1573 case P_PGID: 1574 type = PIDTYPE_PGID; 1575 if (upid <= 0) 1576 return -EINVAL; 1577 break; 1578 default: 1579 return -EINVAL; 1580 } 1581 1582 if (type < PIDTYPE_MAX) 1583 pid = find_get_pid(upid); 1584 1585 wo.wo_type = type; 1586 wo.wo_pid = pid; 1587 wo.wo_flags = options; 1588 wo.wo_info = infop; 1589 wo.wo_stat = NULL; 1590 wo.wo_rusage = ru; 1591 ret = do_wait(&wo); 1592 1593 if (ret > 0) { 1594 ret = 0; 1595 } else if (infop) { 1596 /* 1597 * For a WNOHANG return, clear out all the fields 1598 * we would set so the user can easily tell the 1599 * difference. 1600 */ 1601 if (!ret) 1602 ret = put_user(0, &infop->si_signo); 1603 if (!ret) 1604 ret = put_user(0, &infop->si_errno); 1605 if (!ret) 1606 ret = put_user(0, &infop->si_code); 1607 if (!ret) 1608 ret = put_user(0, &infop->si_pid); 1609 if (!ret) 1610 ret = put_user(0, &infop->si_uid); 1611 if (!ret) 1612 ret = put_user(0, &infop->si_status); 1613 } 1614 1615 put_pid(pid); 1616 return ret; 1617 } 1618 1619 SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, 1620 int, options, struct rusage __user *, ru) 1621 { 1622 struct wait_opts wo; 1623 struct pid *pid = NULL; 1624 enum pid_type type; 1625 long ret; 1626 1627 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| 1628 __WNOTHREAD|__WCLONE|__WALL)) 1629 return -EINVAL; 1630 1631 if (upid == -1) 1632 type = PIDTYPE_MAX; 1633 else if (upid < 0) { 1634 type = PIDTYPE_PGID; 1635 pid = find_get_pid(-upid); 1636 } else if (upid == 0) { 1637 type = PIDTYPE_PGID; 1638 pid = get_task_pid(current, PIDTYPE_PGID); 1639 } else /* upid > 0 */ { 1640 type = PIDTYPE_PID; 1641 pid = find_get_pid(upid); 1642 } 1643 1644 wo.wo_type = type; 1645 wo.wo_pid = pid; 1646 wo.wo_flags = options | WEXITED; 1647 wo.wo_info = NULL; 1648 wo.wo_stat = stat_addr; 1649 wo.wo_rusage = ru; 1650 ret = do_wait(&wo); 1651 put_pid(pid); 1652 1653 return ret; 1654 } 1655 1656 #ifdef __ARCH_WANT_SYS_WAITPID 1657 1658 /* 1659 * sys_waitpid() remains for compatibility. waitpid() should be 1660 * implemented by calling sys_wait4() from libc.a. 1661 */ 1662 SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) 1663 { 1664 return sys_wait4(pid, stat_addr, options, NULL); 1665 } 1666 1667 #endif 1668