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 * If we are the last child process in a pid namespace to be 77 * reaped, notify the reaper sleeping zap_pid_ns_processes(). 78 */ 79 if (IS_ENABLED(CONFIG_PID_NS)) { 80 struct task_struct *parent = p->real_parent; 81 82 if ((task_active_pid_ns(parent)->child_reaper == parent) && 83 list_empty(&parent->children) && 84 (parent->flags & PF_EXITING)) 85 wake_up_process(parent); 86 } 87 } 88 list_del_rcu(&p->thread_group); 89 } 90 91 /* 92 * This function expects the tasklist_lock write-locked. 93 */ 94 static void __exit_signal(struct task_struct *tsk) 95 { 96 struct signal_struct *sig = tsk->signal; 97 bool group_dead = thread_group_leader(tsk); 98 struct sighand_struct *sighand; 99 struct tty_struct *uninitialized_var(tty); 100 101 sighand = rcu_dereference_check(tsk->sighand, 102 lockdep_tasklist_lock_is_held()); 103 spin_lock(&sighand->siglock); 104 105 posix_cpu_timers_exit(tsk); 106 if (group_dead) { 107 posix_cpu_timers_exit_group(tsk); 108 tty = sig->tty; 109 sig->tty = NULL; 110 } else { 111 /* 112 * This can only happen if the caller is de_thread(). 113 * FIXME: this is the temporary hack, we should teach 114 * posix-cpu-timers to handle this case correctly. 115 */ 116 if (unlikely(has_group_leader_pid(tsk))) 117 posix_cpu_timers_exit_group(tsk); 118 119 /* 120 * If there is any task waiting for the group exit 121 * then notify it: 122 */ 123 if (sig->notify_count > 0 && !--sig->notify_count) 124 wake_up_process(sig->group_exit_task); 125 126 if (tsk == sig->curr_target) 127 sig->curr_target = next_thread(tsk); 128 /* 129 * Accumulate here the counters for all threads but the 130 * group leader as they die, so they can be added into 131 * the process-wide totals when those are taken. 132 * The group leader stays around as a zombie as long 133 * as there are other threads. When it gets reaped, 134 * the exit.c code will add its counts into these totals. 135 * We won't ever get here for the group leader, since it 136 * will have been the last reference on the signal_struct. 137 */ 138 sig->utime += tsk->utime; 139 sig->stime += tsk->stime; 140 sig->gtime += tsk->gtime; 141 sig->min_flt += tsk->min_flt; 142 sig->maj_flt += tsk->maj_flt; 143 sig->nvcsw += tsk->nvcsw; 144 sig->nivcsw += tsk->nivcsw; 145 sig->inblock += task_io_get_inblock(tsk); 146 sig->oublock += task_io_get_oublock(tsk); 147 task_io_accounting_add(&sig->ioac, &tsk->ioac); 148 sig->sum_sched_runtime += tsk->se.sum_exec_runtime; 149 } 150 151 sig->nr_threads--; 152 __unhash_process(tsk, group_dead); 153 154 /* 155 * Do this under ->siglock, we can race with another thread 156 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. 157 */ 158 flush_sigqueue(&tsk->pending); 159 tsk->sighand = NULL; 160 spin_unlock(&sighand->siglock); 161 162 __cleanup_sighand(sighand); 163 clear_tsk_thread_flag(tsk,TIF_SIGPENDING); 164 if (group_dead) { 165 flush_sigqueue(&sig->shared_pending); 166 tty_kref_put(tty); 167 } 168 } 169 170 static void delayed_put_task_struct(struct rcu_head *rhp) 171 { 172 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); 173 174 perf_event_delayed_put(tsk); 175 trace_sched_process_free(tsk); 176 put_task_struct(tsk); 177 } 178 179 180 void release_task(struct task_struct * p) 181 { 182 struct task_struct *leader; 183 int zap_leader; 184 repeat: 185 /* don't need to get the RCU readlock here - the process is dead and 186 * can't be modifying its own credentials. But shut RCU-lockdep up */ 187 rcu_read_lock(); 188 atomic_dec(&__task_cred(p)->user->processes); 189 rcu_read_unlock(); 190 191 proc_flush_task(p); 192 193 write_lock_irq(&tasklist_lock); 194 ptrace_release_task(p); 195 __exit_signal(p); 196 197 /* 198 * If we are the last non-leader member of the thread 199 * group, and the leader is zombie, then notify the 200 * group leader's parent process. (if it wants notification.) 201 */ 202 zap_leader = 0; 203 leader = p->group_leader; 204 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) { 205 /* 206 * If we were the last child thread and the leader has 207 * exited already, and the leader's parent ignores SIGCHLD, 208 * then we are the one who should release the leader. 209 */ 210 zap_leader = do_notify_parent(leader, leader->exit_signal); 211 if (zap_leader) 212 leader->exit_state = EXIT_DEAD; 213 } 214 215 write_unlock_irq(&tasklist_lock); 216 release_thread(p); 217 call_rcu(&p->rcu, delayed_put_task_struct); 218 219 p = leader; 220 if (unlikely(zap_leader)) 221 goto repeat; 222 } 223 224 /* 225 * This checks not only the pgrp, but falls back on the pid if no 226 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly 227 * without this... 228 * 229 * The caller must hold rcu lock or the tasklist lock. 230 */ 231 struct pid *session_of_pgrp(struct pid *pgrp) 232 { 233 struct task_struct *p; 234 struct pid *sid = NULL; 235 236 p = pid_task(pgrp, PIDTYPE_PGID); 237 if (p == NULL) 238 p = pid_task(pgrp, PIDTYPE_PID); 239 if (p != NULL) 240 sid = task_session(p); 241 242 return sid; 243 } 244 245 /* 246 * Determine if a process group is "orphaned", according to the POSIX 247 * definition in 2.2.2.52. Orphaned process groups are not to be affected 248 * by terminal-generated stop signals. Newly orphaned process groups are 249 * to receive a SIGHUP and a SIGCONT. 250 * 251 * "I ask you, have you ever known what it is to be an orphan?" 252 */ 253 static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task) 254 { 255 struct task_struct *p; 256 257 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 258 if ((p == ignored_task) || 259 (p->exit_state && thread_group_empty(p)) || 260 is_global_init(p->real_parent)) 261 continue; 262 263 if (task_pgrp(p->real_parent) != pgrp && 264 task_session(p->real_parent) == task_session(p)) 265 return 0; 266 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 267 268 return 1; 269 } 270 271 int is_current_pgrp_orphaned(void) 272 { 273 int retval; 274 275 read_lock(&tasklist_lock); 276 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); 277 read_unlock(&tasklist_lock); 278 279 return retval; 280 } 281 282 static bool has_stopped_jobs(struct pid *pgrp) 283 { 284 struct task_struct *p; 285 286 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 287 if (p->signal->flags & SIGNAL_STOP_STOPPED) 288 return true; 289 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 290 291 return false; 292 } 293 294 /* 295 * Check to see if any process groups have become orphaned as 296 * a result of our exiting, and if they have any stopped jobs, 297 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 298 */ 299 static void 300 kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) 301 { 302 struct pid *pgrp = task_pgrp(tsk); 303 struct task_struct *ignored_task = tsk; 304 305 if (!parent) 306 /* exit: our father is in a different pgrp than 307 * we are and we were the only connection outside. 308 */ 309 parent = tsk->real_parent; 310 else 311 /* reparent: our child is in a different pgrp than 312 * we are, and it was the only connection outside. 313 */ 314 ignored_task = NULL; 315 316 if (task_pgrp(parent) != pgrp && 317 task_session(parent) == task_session(tsk) && 318 will_become_orphaned_pgrp(pgrp, ignored_task) && 319 has_stopped_jobs(pgrp)) { 320 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); 321 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); 322 } 323 } 324 325 /** 326 * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd 327 * 328 * If a kernel thread is launched as a result of a system call, or if 329 * it ever exits, it should generally reparent itself to kthreadd so it 330 * isn't in the way of other processes and is correctly cleaned up on exit. 331 * 332 * The various task state such as scheduling policy and priority may have 333 * been inherited from a user process, so we reset them to sane values here. 334 * 335 * NOTE that reparent_to_kthreadd() gives the caller full capabilities. 336 */ 337 static void reparent_to_kthreadd(void) 338 { 339 write_lock_irq(&tasklist_lock); 340 341 ptrace_unlink(current); 342 /* Reparent to init */ 343 current->real_parent = current->parent = kthreadd_task; 344 list_move_tail(¤t->sibling, ¤t->real_parent->children); 345 346 /* Set the exit signal to SIGCHLD so we signal init on exit */ 347 current->exit_signal = SIGCHLD; 348 349 if (task_nice(current) < 0) 350 set_user_nice(current, 0); 351 /* cpus_allowed? */ 352 /* rt_priority? */ 353 /* signals? */ 354 memcpy(current->signal->rlim, init_task.signal->rlim, 355 sizeof(current->signal->rlim)); 356 357 atomic_inc(&init_cred.usage); 358 commit_creds(&init_cred); 359 write_unlock_irq(&tasklist_lock); 360 } 361 362 void __set_special_pids(struct pid *pid) 363 { 364 struct task_struct *curr = current->group_leader; 365 366 if (task_session(curr) != pid) 367 change_pid(curr, PIDTYPE_SID, pid); 368 369 if (task_pgrp(curr) != pid) 370 change_pid(curr, PIDTYPE_PGID, pid); 371 } 372 373 static void set_special_pids(struct pid *pid) 374 { 375 write_lock_irq(&tasklist_lock); 376 __set_special_pids(pid); 377 write_unlock_irq(&tasklist_lock); 378 } 379 380 /* 381 * Let kernel threads use this to say that they allow a certain signal. 382 * Must not be used if kthread was cloned with CLONE_SIGHAND. 383 */ 384 int allow_signal(int sig) 385 { 386 if (!valid_signal(sig) || sig < 1) 387 return -EINVAL; 388 389 spin_lock_irq(¤t->sighand->siglock); 390 /* This is only needed for daemonize()'ed kthreads */ 391 sigdelset(¤t->blocked, sig); 392 /* 393 * Kernel threads handle their own signals. Let the signal code 394 * know it'll be handled, so that they don't get converted to 395 * SIGKILL or just silently dropped. 396 */ 397 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2; 398 recalc_sigpending(); 399 spin_unlock_irq(¤t->sighand->siglock); 400 return 0; 401 } 402 403 EXPORT_SYMBOL(allow_signal); 404 405 int disallow_signal(int sig) 406 { 407 if (!valid_signal(sig) || sig < 1) 408 return -EINVAL; 409 410 spin_lock_irq(¤t->sighand->siglock); 411 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN; 412 recalc_sigpending(); 413 spin_unlock_irq(¤t->sighand->siglock); 414 return 0; 415 } 416 417 EXPORT_SYMBOL(disallow_signal); 418 419 /* 420 * Put all the gunge required to become a kernel thread without 421 * attached user resources in one place where it belongs. 422 */ 423 424 void daemonize(const char *name, ...) 425 { 426 va_list args; 427 sigset_t blocked; 428 429 va_start(args, name); 430 vsnprintf(current->comm, sizeof(current->comm), name, args); 431 va_end(args); 432 433 /* 434 * If we were started as result of loading a module, close all of the 435 * user space pages. We don't need them, and if we didn't close them 436 * they would be locked into memory. 437 */ 438 exit_mm(current); 439 /* 440 * We don't want to get frozen, in case system-wide hibernation 441 * or suspend transition begins right now. 442 */ 443 current->flags |= (PF_NOFREEZE | PF_KTHREAD); 444 445 if (current->nsproxy != &init_nsproxy) { 446 get_nsproxy(&init_nsproxy); 447 switch_task_namespaces(current, &init_nsproxy); 448 } 449 set_special_pids(&init_struct_pid); 450 proc_clear_tty(current); 451 452 /* Block and flush all signals */ 453 sigfillset(&blocked); 454 sigprocmask(SIG_BLOCK, &blocked, NULL); 455 flush_signals(current); 456 457 /* Become as one with the init task */ 458 459 daemonize_fs_struct(); 460 daemonize_descriptors(); 461 462 reparent_to_kthreadd(); 463 } 464 465 EXPORT_SYMBOL(daemonize); 466 467 #ifdef CONFIG_MM_OWNER 468 /* 469 * A task is exiting. If it owned this mm, find a new owner for the mm. 470 */ 471 void mm_update_next_owner(struct mm_struct *mm) 472 { 473 struct task_struct *c, *g, *p = current; 474 475 retry: 476 /* 477 * If the exiting or execing task is not the owner, it's 478 * someone else's problem. 479 */ 480 if (mm->owner != p) 481 return; 482 /* 483 * The current owner is exiting/execing and there are no other 484 * candidates. Do not leave the mm pointing to a possibly 485 * freed task structure. 486 */ 487 if (atomic_read(&mm->mm_users) <= 1) { 488 mm->owner = NULL; 489 return; 490 } 491 492 read_lock(&tasklist_lock); 493 /* 494 * Search in the children 495 */ 496 list_for_each_entry(c, &p->children, sibling) { 497 if (c->mm == mm) 498 goto assign_new_owner; 499 } 500 501 /* 502 * Search in the siblings 503 */ 504 list_for_each_entry(c, &p->real_parent->children, sibling) { 505 if (c->mm == mm) 506 goto assign_new_owner; 507 } 508 509 /* 510 * Search through everything else. We should not get 511 * here often 512 */ 513 do_each_thread(g, c) { 514 if (c->mm == mm) 515 goto assign_new_owner; 516 } while_each_thread(g, c); 517 518 read_unlock(&tasklist_lock); 519 /* 520 * We found no owner yet mm_users > 1: this implies that we are 521 * most likely racing with swapoff (try_to_unuse()) or /proc or 522 * ptrace or page migration (get_task_mm()). Mark owner as NULL. 523 */ 524 mm->owner = NULL; 525 return; 526 527 assign_new_owner: 528 BUG_ON(c == p); 529 get_task_struct(c); 530 /* 531 * The task_lock protects c->mm from changing. 532 * We always want mm->owner->mm == mm 533 */ 534 task_lock(c); 535 /* 536 * Delay read_unlock() till we have the task_lock() 537 * to ensure that c does not slip away underneath us 538 */ 539 read_unlock(&tasklist_lock); 540 if (c->mm != mm) { 541 task_unlock(c); 542 put_task_struct(c); 543 goto retry; 544 } 545 mm->owner = c; 546 task_unlock(c); 547 put_task_struct(c); 548 } 549 #endif /* CONFIG_MM_OWNER */ 550 551 /* 552 * Turn us into a lazy TLB process if we 553 * aren't already.. 554 */ 555 static void exit_mm(struct task_struct * tsk) 556 { 557 struct mm_struct *mm = tsk->mm; 558 struct core_state *core_state; 559 560 mm_release(tsk, mm); 561 if (!mm) 562 return; 563 sync_mm_rss(mm); 564 /* 565 * Serialize with any possible pending coredump. 566 * We must hold mmap_sem around checking core_state 567 * and clearing tsk->mm. The core-inducing thread 568 * will increment ->nr_threads for each thread in the 569 * group with ->mm != NULL. 570 */ 571 down_read(&mm->mmap_sem); 572 core_state = mm->core_state; 573 if (core_state) { 574 struct core_thread self; 575 up_read(&mm->mmap_sem); 576 577 self.task = tsk; 578 self.next = xchg(&core_state->dumper.next, &self); 579 /* 580 * Implies mb(), the result of xchg() must be visible 581 * to core_state->dumper. 582 */ 583 if (atomic_dec_and_test(&core_state->nr_threads)) 584 complete(&core_state->startup); 585 586 for (;;) { 587 set_task_state(tsk, TASK_UNINTERRUPTIBLE); 588 if (!self.task) /* see coredump_finish() */ 589 break; 590 schedule(); 591 } 592 __set_task_state(tsk, TASK_RUNNING); 593 down_read(&mm->mmap_sem); 594 } 595 atomic_inc(&mm->mm_count); 596 BUG_ON(mm != tsk->active_mm); 597 /* more a memory barrier than a real lock */ 598 task_lock(tsk); 599 tsk->mm = NULL; 600 up_read(&mm->mmap_sem); 601 enter_lazy_tlb(mm, current); 602 task_unlock(tsk); 603 mm_update_next_owner(mm); 604 mmput(mm); 605 } 606 607 /* 608 * When we die, we re-parent all our children, and try to: 609 * 1. give them to another thread in our thread group, if such a member exists 610 * 2. give it to the first ancestor process which prctl'd itself as a 611 * child_subreaper for its children (like a service manager) 612 * 3. give it to the init process (PID 1) in our pid namespace 613 */ 614 static struct task_struct *find_new_reaper(struct task_struct *father) 615 __releases(&tasklist_lock) 616 __acquires(&tasklist_lock) 617 { 618 struct pid_namespace *pid_ns = task_active_pid_ns(father); 619 struct task_struct *thread; 620 621 thread = father; 622 while_each_thread(father, thread) { 623 if (thread->flags & PF_EXITING) 624 continue; 625 if (unlikely(pid_ns->child_reaper == father)) 626 pid_ns->child_reaper = thread; 627 return thread; 628 } 629 630 if (unlikely(pid_ns->child_reaper == father)) { 631 write_unlock_irq(&tasklist_lock); 632 if (unlikely(pid_ns == &init_pid_ns)) { 633 panic("Attempted to kill init! exitcode=0x%08x\n", 634 father->signal->group_exit_code ?: 635 father->exit_code); 636 } 637 638 zap_pid_ns_processes(pid_ns); 639 write_lock_irq(&tasklist_lock); 640 } else if (father->signal->has_child_subreaper) { 641 struct task_struct *reaper; 642 643 /* 644 * Find the first ancestor marked as child_subreaper. 645 * Note that the code below checks same_thread_group(reaper, 646 * pid_ns->child_reaper). This is what we need to DTRT in a 647 * PID namespace. However we still need the check above, see 648 * http://marc.info/?l=linux-kernel&m=131385460420380 649 */ 650 for (reaper = father->real_parent; 651 reaper != &init_task; 652 reaper = reaper->real_parent) { 653 if (same_thread_group(reaper, pid_ns->child_reaper)) 654 break; 655 if (!reaper->signal->is_child_subreaper) 656 continue; 657 thread = reaper; 658 do { 659 if (!(thread->flags & PF_EXITING)) 660 return reaper; 661 } while_each_thread(reaper, thread); 662 } 663 } 664 665 return pid_ns->child_reaper; 666 } 667 668 /* 669 * Any that need to be release_task'd are put on the @dead list. 670 */ 671 static void reparent_leader(struct task_struct *father, struct task_struct *p, 672 struct list_head *dead) 673 { 674 list_move_tail(&p->sibling, &p->real_parent->children); 675 676 if (p->exit_state == EXIT_DEAD) 677 return; 678 /* 679 * If this is a threaded reparent there is no need to 680 * notify anyone anything has happened. 681 */ 682 if (same_thread_group(p->real_parent, father)) 683 return; 684 685 /* We don't want people slaying init. */ 686 p->exit_signal = SIGCHLD; 687 688 /* If it has exited notify the new parent about this child's death. */ 689 if (!p->ptrace && 690 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { 691 if (do_notify_parent(p, p->exit_signal)) { 692 p->exit_state = EXIT_DEAD; 693 list_move_tail(&p->sibling, dead); 694 } 695 } 696 697 kill_orphaned_pgrp(p, father); 698 } 699 700 static void forget_original_parent(struct task_struct *father) 701 { 702 struct task_struct *p, *n, *reaper; 703 LIST_HEAD(dead_children); 704 705 write_lock_irq(&tasklist_lock); 706 /* 707 * Note that exit_ptrace() and find_new_reaper() might 708 * drop tasklist_lock and reacquire it. 709 */ 710 exit_ptrace(father); 711 reaper = find_new_reaper(father); 712 713 list_for_each_entry_safe(p, n, &father->children, sibling) { 714 struct task_struct *t = p; 715 do { 716 t->real_parent = reaper; 717 if (t->parent == father) { 718 BUG_ON(t->ptrace); 719 t->parent = t->real_parent; 720 } 721 if (t->pdeath_signal) 722 group_send_sig_info(t->pdeath_signal, 723 SEND_SIG_NOINFO, t); 724 } while_each_thread(p, t); 725 reparent_leader(father, p, &dead_children); 726 } 727 write_unlock_irq(&tasklist_lock); 728 729 BUG_ON(!list_empty(&father->children)); 730 731 list_for_each_entry_safe(p, n, &dead_children, sibling) { 732 list_del_init(&p->sibling); 733 release_task(p); 734 } 735 } 736 737 /* 738 * Send signals to all our closest relatives so that they know 739 * to properly mourn us.. 740 */ 741 static void exit_notify(struct task_struct *tsk, int group_dead) 742 { 743 bool autoreap; 744 745 /* 746 * This does two things: 747 * 748 * A. Make init inherit all the child processes 749 * B. Check to see if any process groups have become orphaned 750 * as a result of our exiting, and if they have any stopped 751 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 752 */ 753 forget_original_parent(tsk); 754 exit_task_namespaces(tsk); 755 756 write_lock_irq(&tasklist_lock); 757 if (group_dead) 758 kill_orphaned_pgrp(tsk->group_leader, NULL); 759 760 if (unlikely(tsk->ptrace)) { 761 int sig = thread_group_leader(tsk) && 762 thread_group_empty(tsk) && 763 !ptrace_reparented(tsk) ? 764 tsk->exit_signal : SIGCHLD; 765 autoreap = do_notify_parent(tsk, sig); 766 } else if (thread_group_leader(tsk)) { 767 autoreap = thread_group_empty(tsk) && 768 do_notify_parent(tsk, tsk->exit_signal); 769 } else { 770 autoreap = true; 771 } 772 773 tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE; 774 775 /* mt-exec, de_thread() is waiting for group leader */ 776 if (unlikely(tsk->signal->notify_count < 0)) 777 wake_up_process(tsk->signal->group_exit_task); 778 write_unlock_irq(&tasklist_lock); 779 780 /* If the process is dead, release it - nobody will wait for it */ 781 if (autoreap) 782 release_task(tsk); 783 } 784 785 #ifdef CONFIG_DEBUG_STACK_USAGE 786 static void check_stack_usage(void) 787 { 788 static DEFINE_SPINLOCK(low_water_lock); 789 static int lowest_to_date = THREAD_SIZE; 790 unsigned long free; 791 792 free = stack_not_used(current); 793 794 if (free >= lowest_to_date) 795 return; 796 797 spin_lock(&low_water_lock); 798 if (free < lowest_to_date) { 799 printk(KERN_WARNING "%s (%d) used greatest stack depth: " 800 "%lu bytes left\n", 801 current->comm, task_pid_nr(current), free); 802 lowest_to_date = free; 803 } 804 spin_unlock(&low_water_lock); 805 } 806 #else 807 static inline void check_stack_usage(void) {} 808 #endif 809 810 void do_exit(long code) 811 { 812 struct task_struct *tsk = current; 813 int group_dead; 814 815 profile_task_exit(tsk); 816 817 WARN_ON(blk_needs_flush_plug(tsk)); 818 819 if (unlikely(in_interrupt())) 820 panic("Aiee, killing interrupt handler!"); 821 if (unlikely(!tsk->pid)) 822 panic("Attempted to kill the idle task!"); 823 824 /* 825 * If do_exit is called because this processes oopsed, it's possible 826 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before 827 * continuing. Amongst other possible reasons, this is to prevent 828 * mm_release()->clear_child_tid() from writing to a user-controlled 829 * kernel address. 830 */ 831 set_fs(USER_DS); 832 833 ptrace_event(PTRACE_EVENT_EXIT, code); 834 835 validate_creds_for_do_exit(tsk); 836 837 /* 838 * We're taking recursive faults here in do_exit. Safest is to just 839 * leave this task alone and wait for reboot. 840 */ 841 if (unlikely(tsk->flags & PF_EXITING)) { 842 printk(KERN_ALERT 843 "Fixing recursive fault but reboot is needed!\n"); 844 /* 845 * We can do this unlocked here. The futex code uses 846 * this flag just to verify whether the pi state 847 * cleanup has been done or not. In the worst case it 848 * loops once more. We pretend that the cleanup was 849 * done as there is no way to return. Either the 850 * OWNER_DIED bit is set by now or we push the blocked 851 * task into the wait for ever nirwana as well. 852 */ 853 tsk->flags |= PF_EXITPIDONE; 854 set_current_state(TASK_UNINTERRUPTIBLE); 855 schedule(); 856 } 857 858 exit_signals(tsk); /* sets PF_EXITING */ 859 /* 860 * tsk->flags are checked in the futex code to protect against 861 * an exiting task cleaning up the robust pi futexes. 862 */ 863 smp_mb(); 864 raw_spin_unlock_wait(&tsk->pi_lock); 865 866 if (unlikely(in_atomic())) 867 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n", 868 current->comm, task_pid_nr(current), 869 preempt_count()); 870 871 acct_update_integrals(tsk); 872 /* sync mm's RSS info before statistics gathering */ 873 if (tsk->mm) 874 sync_mm_rss(tsk->mm); 875 group_dead = atomic_dec_and_test(&tsk->signal->live); 876 if (group_dead) { 877 hrtimer_cancel(&tsk->signal->real_timer); 878 exit_itimers(tsk->signal); 879 if (tsk->mm) 880 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); 881 } 882 acct_collect(code, group_dead); 883 if (group_dead) 884 tty_audit_exit(); 885 audit_free(tsk); 886 887 tsk->exit_code = code; 888 taskstats_exit(tsk, group_dead); 889 890 exit_mm(tsk); 891 892 if (group_dead) 893 acct_process(); 894 trace_sched_process_exit(tsk); 895 896 exit_sem(tsk); 897 exit_shm(tsk); 898 exit_files(tsk); 899 exit_fs(tsk); 900 exit_task_work(tsk); 901 check_stack_usage(); 902 exit_thread(); 903 904 /* 905 * Flush inherited counters to the parent - before the parent 906 * gets woken up by child-exit notifications. 907 * 908 * because of cgroup mode, must be called before cgroup_exit() 909 */ 910 perf_event_exit_task(tsk); 911 912 cgroup_exit(tsk, 1); 913 914 if (group_dead) 915 disassociate_ctty(1); 916 917 module_put(task_thread_info(tsk)->exec_domain->module); 918 919 proc_exit_connector(tsk); 920 921 /* 922 * FIXME: do that only when needed, using sched_exit tracepoint 923 */ 924 ptrace_put_breakpoints(tsk); 925 926 exit_notify(tsk, group_dead); 927 #ifdef CONFIG_NUMA 928 task_lock(tsk); 929 mpol_put(tsk->mempolicy); 930 tsk->mempolicy = NULL; 931 task_unlock(tsk); 932 #endif 933 #ifdef CONFIG_FUTEX 934 if (unlikely(current->pi_state_cache)) 935 kfree(current->pi_state_cache); 936 #endif 937 /* 938 * Make sure we are holding no locks: 939 */ 940 debug_check_no_locks_held(tsk); 941 /* 942 * We can do this unlocked here. The futex code uses this flag 943 * just to verify whether the pi state cleanup has been done 944 * or not. In the worst case it loops once more. 945 */ 946 tsk->flags |= PF_EXITPIDONE; 947 948 if (tsk->io_context) 949 exit_io_context(tsk); 950 951 if (tsk->splice_pipe) 952 __free_pipe_info(tsk->splice_pipe); 953 954 if (tsk->task_frag.page) 955 put_page(tsk->task_frag.page); 956 957 validate_creds_for_do_exit(tsk); 958 959 preempt_disable(); 960 if (tsk->nr_dirtied) 961 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); 962 exit_rcu(); 963 964 /* 965 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed 966 * when the following two conditions become true. 967 * - There is race condition of mmap_sem (It is acquired by 968 * exit_mm()), and 969 * - SMI occurs before setting TASK_RUNINNG. 970 * (or hypervisor of virtual machine switches to other guest) 971 * As a result, we may become TASK_RUNNING after becoming TASK_DEAD 972 * 973 * To avoid it, we have to wait for releasing tsk->pi_lock which 974 * is held by try_to_wake_up() 975 */ 976 smp_mb(); 977 raw_spin_unlock_wait(&tsk->pi_lock); 978 979 /* causes final put_task_struct in finish_task_switch(). */ 980 tsk->state = TASK_DEAD; 981 tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */ 982 schedule(); 983 BUG(); 984 /* Avoid "noreturn function does return". */ 985 for (;;) 986 cpu_relax(); /* For when BUG is null */ 987 } 988 989 EXPORT_SYMBOL_GPL(do_exit); 990 991 void complete_and_exit(struct completion *comp, long code) 992 { 993 if (comp) 994 complete(comp); 995 996 do_exit(code); 997 } 998 999 EXPORT_SYMBOL(complete_and_exit); 1000 1001 SYSCALL_DEFINE1(exit, int, error_code) 1002 { 1003 do_exit((error_code&0xff)<<8); 1004 } 1005 1006 /* 1007 * Take down every thread in the group. This is called by fatal signals 1008 * as well as by sys_exit_group (below). 1009 */ 1010 void 1011 do_group_exit(int exit_code) 1012 { 1013 struct signal_struct *sig = current->signal; 1014 1015 BUG_ON(exit_code & 0x80); /* core dumps don't get here */ 1016 1017 if (signal_group_exit(sig)) 1018 exit_code = sig->group_exit_code; 1019 else if (!thread_group_empty(current)) { 1020 struct sighand_struct *const sighand = current->sighand; 1021 spin_lock_irq(&sighand->siglock); 1022 if (signal_group_exit(sig)) 1023 /* Another thread got here before we took the lock. */ 1024 exit_code = sig->group_exit_code; 1025 else { 1026 sig->group_exit_code = exit_code; 1027 sig->flags = SIGNAL_GROUP_EXIT; 1028 zap_other_threads(current); 1029 } 1030 spin_unlock_irq(&sighand->siglock); 1031 } 1032 1033 do_exit(exit_code); 1034 /* NOTREACHED */ 1035 } 1036 1037 /* 1038 * this kills every thread in the thread group. Note that any externally 1039 * wait4()-ing process will get the correct exit code - even if this 1040 * thread is not the thread group leader. 1041 */ 1042 SYSCALL_DEFINE1(exit_group, int, error_code) 1043 { 1044 do_group_exit((error_code & 0xff) << 8); 1045 /* NOTREACHED */ 1046 return 0; 1047 } 1048 1049 struct wait_opts { 1050 enum pid_type wo_type; 1051 int wo_flags; 1052 struct pid *wo_pid; 1053 1054 struct siginfo __user *wo_info; 1055 int __user *wo_stat; 1056 struct rusage __user *wo_rusage; 1057 1058 wait_queue_t child_wait; 1059 int notask_error; 1060 }; 1061 1062 static inline 1063 struct pid *task_pid_type(struct task_struct *task, enum pid_type type) 1064 { 1065 if (type != PIDTYPE_PID) 1066 task = task->group_leader; 1067 return task->pids[type].pid; 1068 } 1069 1070 static int eligible_pid(struct wait_opts *wo, struct task_struct *p) 1071 { 1072 return wo->wo_type == PIDTYPE_MAX || 1073 task_pid_type(p, wo->wo_type) == wo->wo_pid; 1074 } 1075 1076 static int eligible_child(struct wait_opts *wo, struct task_struct *p) 1077 { 1078 if (!eligible_pid(wo, p)) 1079 return 0; 1080 /* Wait for all children (clone and not) if __WALL is set; 1081 * otherwise, wait for clone children *only* if __WCLONE is 1082 * set; otherwise, wait for non-clone children *only*. (Note: 1083 * A "clone" child here is one that reports to its parent 1084 * using a signal other than SIGCHLD.) */ 1085 if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) 1086 && !(wo->wo_flags & __WALL)) 1087 return 0; 1088 1089 return 1; 1090 } 1091 1092 static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p, 1093 pid_t pid, uid_t uid, int why, int status) 1094 { 1095 struct siginfo __user *infop; 1096 int retval = wo->wo_rusage 1097 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; 1098 1099 put_task_struct(p); 1100 infop = wo->wo_info; 1101 if (infop) { 1102 if (!retval) 1103 retval = put_user(SIGCHLD, &infop->si_signo); 1104 if (!retval) 1105 retval = put_user(0, &infop->si_errno); 1106 if (!retval) 1107 retval = put_user((short)why, &infop->si_code); 1108 if (!retval) 1109 retval = put_user(pid, &infop->si_pid); 1110 if (!retval) 1111 retval = put_user(uid, &infop->si_uid); 1112 if (!retval) 1113 retval = put_user(status, &infop->si_status); 1114 } 1115 if (!retval) 1116 retval = pid; 1117 return retval; 1118 } 1119 1120 /* 1121 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold 1122 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1123 * the lock and this task is uninteresting. If we return nonzero, we have 1124 * released the lock and the system call should return. 1125 */ 1126 static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) 1127 { 1128 unsigned long state; 1129 int retval, status, traced; 1130 pid_t pid = task_pid_vnr(p); 1131 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1132 struct siginfo __user *infop; 1133 1134 if (!likely(wo->wo_flags & WEXITED)) 1135 return 0; 1136 1137 if (unlikely(wo->wo_flags & WNOWAIT)) { 1138 int exit_code = p->exit_code; 1139 int why; 1140 1141 get_task_struct(p); 1142 read_unlock(&tasklist_lock); 1143 if ((exit_code & 0x7f) == 0) { 1144 why = CLD_EXITED; 1145 status = exit_code >> 8; 1146 } else { 1147 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED; 1148 status = exit_code & 0x7f; 1149 } 1150 return wait_noreap_copyout(wo, p, pid, uid, why, status); 1151 } 1152 1153 /* 1154 * Try to move the task's state to DEAD 1155 * only one thread is allowed to do this: 1156 */ 1157 state = xchg(&p->exit_state, EXIT_DEAD); 1158 if (state != EXIT_ZOMBIE) { 1159 BUG_ON(state != EXIT_DEAD); 1160 return 0; 1161 } 1162 1163 traced = ptrace_reparented(p); 1164 /* 1165 * It can be ptraced but not reparented, check 1166 * thread_group_leader() to filter out sub-threads. 1167 */ 1168 if (likely(!traced) && thread_group_leader(p)) { 1169 struct signal_struct *psig; 1170 struct signal_struct *sig; 1171 unsigned long maxrss; 1172 cputime_t tgutime, tgstime; 1173 1174 /* 1175 * The resource counters for the group leader are in its 1176 * own task_struct. Those for dead threads in the group 1177 * are in its signal_struct, as are those for the child 1178 * processes it has previously reaped. All these 1179 * accumulate in the parent's signal_struct c* fields. 1180 * 1181 * We don't bother to take a lock here to protect these 1182 * p->signal fields, because they are only touched by 1183 * __exit_signal, which runs with tasklist_lock 1184 * write-locked anyway, and so is excluded here. We do 1185 * need to protect the access to parent->signal fields, 1186 * as other threads in the parent group can be right 1187 * here reaping other children at the same time. 1188 * 1189 * We use thread_group_times() to get times for the thread 1190 * group, which consolidates times for all threads in the 1191 * group including the group leader. 1192 */ 1193 thread_group_times(p, &tgutime, &tgstime); 1194 spin_lock_irq(&p->real_parent->sighand->siglock); 1195 psig = p->real_parent->signal; 1196 sig = p->signal; 1197 psig->cutime += tgutime + sig->cutime; 1198 psig->cstime += tgstime + sig->cstime; 1199 psig->cgtime += p->gtime + sig->gtime + sig->cgtime; 1200 psig->cmin_flt += 1201 p->min_flt + sig->min_flt + sig->cmin_flt; 1202 psig->cmaj_flt += 1203 p->maj_flt + sig->maj_flt + sig->cmaj_flt; 1204 psig->cnvcsw += 1205 p->nvcsw + sig->nvcsw + sig->cnvcsw; 1206 psig->cnivcsw += 1207 p->nivcsw + sig->nivcsw + sig->cnivcsw; 1208 psig->cinblock += 1209 task_io_get_inblock(p) + 1210 sig->inblock + sig->cinblock; 1211 psig->coublock += 1212 task_io_get_oublock(p) + 1213 sig->oublock + sig->coublock; 1214 maxrss = max(sig->maxrss, sig->cmaxrss); 1215 if (psig->cmaxrss < maxrss) 1216 psig->cmaxrss = maxrss; 1217 task_io_accounting_add(&psig->ioac, &p->ioac); 1218 task_io_accounting_add(&psig->ioac, &sig->ioac); 1219 spin_unlock_irq(&p->real_parent->sighand->siglock); 1220 } 1221 1222 /* 1223 * Now we are sure this task is interesting, and no other 1224 * thread can reap it because we set its state to EXIT_DEAD. 1225 */ 1226 read_unlock(&tasklist_lock); 1227 1228 retval = wo->wo_rusage 1229 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; 1230 status = (p->signal->flags & SIGNAL_GROUP_EXIT) 1231 ? p->signal->group_exit_code : p->exit_code; 1232 if (!retval && wo->wo_stat) 1233 retval = put_user(status, wo->wo_stat); 1234 1235 infop = wo->wo_info; 1236 if (!retval && infop) 1237 retval = put_user(SIGCHLD, &infop->si_signo); 1238 if (!retval && infop) 1239 retval = put_user(0, &infop->si_errno); 1240 if (!retval && infop) { 1241 int why; 1242 1243 if ((status & 0x7f) == 0) { 1244 why = CLD_EXITED; 1245 status >>= 8; 1246 } else { 1247 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; 1248 status &= 0x7f; 1249 } 1250 retval = put_user((short)why, &infop->si_code); 1251 if (!retval) 1252 retval = put_user(status, &infop->si_status); 1253 } 1254 if (!retval && infop) 1255 retval = put_user(pid, &infop->si_pid); 1256 if (!retval && infop) 1257 retval = put_user(uid, &infop->si_uid); 1258 if (!retval) 1259 retval = pid; 1260 1261 if (traced) { 1262 write_lock_irq(&tasklist_lock); 1263 /* We dropped tasklist, ptracer could die and untrace */ 1264 ptrace_unlink(p); 1265 /* 1266 * If this is not a sub-thread, notify the parent. 1267 * If parent wants a zombie, don't release it now. 1268 */ 1269 if (thread_group_leader(p) && 1270 !do_notify_parent(p, p->exit_signal)) { 1271 p->exit_state = EXIT_ZOMBIE; 1272 p = NULL; 1273 } 1274 write_unlock_irq(&tasklist_lock); 1275 } 1276 if (p != NULL) 1277 release_task(p); 1278 1279 return retval; 1280 } 1281 1282 static int *task_stopped_code(struct task_struct *p, bool ptrace) 1283 { 1284 if (ptrace) { 1285 if (task_is_stopped_or_traced(p) && 1286 !(p->jobctl & JOBCTL_LISTENING)) 1287 return &p->exit_code; 1288 } else { 1289 if (p->signal->flags & SIGNAL_STOP_STOPPED) 1290 return &p->signal->group_exit_code; 1291 } 1292 return NULL; 1293 } 1294 1295 /** 1296 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED 1297 * @wo: wait options 1298 * @ptrace: is the wait for ptrace 1299 * @p: task to wait for 1300 * 1301 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED. 1302 * 1303 * CONTEXT: 1304 * read_lock(&tasklist_lock), which is released if return value is 1305 * non-zero. Also, grabs and releases @p->sighand->siglock. 1306 * 1307 * RETURNS: 1308 * 0 if wait condition didn't exist and search for other wait conditions 1309 * should continue. Non-zero return, -errno on failure and @p's pid on 1310 * success, implies that tasklist_lock is released and wait condition 1311 * search should terminate. 1312 */ 1313 static int wait_task_stopped(struct wait_opts *wo, 1314 int ptrace, struct task_struct *p) 1315 { 1316 struct siginfo __user *infop; 1317 int retval, exit_code, *p_code, why; 1318 uid_t uid = 0; /* unneeded, required by compiler */ 1319 pid_t pid; 1320 1321 /* 1322 * Traditionally we see ptrace'd stopped tasks regardless of options. 1323 */ 1324 if (!ptrace && !(wo->wo_flags & WUNTRACED)) 1325 return 0; 1326 1327 if (!task_stopped_code(p, ptrace)) 1328 return 0; 1329 1330 exit_code = 0; 1331 spin_lock_irq(&p->sighand->siglock); 1332 1333 p_code = task_stopped_code(p, ptrace); 1334 if (unlikely(!p_code)) 1335 goto unlock_sig; 1336 1337 exit_code = *p_code; 1338 if (!exit_code) 1339 goto unlock_sig; 1340 1341 if (!unlikely(wo->wo_flags & WNOWAIT)) 1342 *p_code = 0; 1343 1344 uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1345 unlock_sig: 1346 spin_unlock_irq(&p->sighand->siglock); 1347 if (!exit_code) 1348 return 0; 1349 1350 /* 1351 * Now we are pretty sure this task is interesting. 1352 * Make sure it doesn't get reaped out from under us while we 1353 * give up the lock and then examine it below. We don't want to 1354 * keep holding onto the tasklist_lock while we call getrusage and 1355 * possibly take page faults for user memory. 1356 */ 1357 get_task_struct(p); 1358 pid = task_pid_vnr(p); 1359 why = ptrace ? CLD_TRAPPED : CLD_STOPPED; 1360 read_unlock(&tasklist_lock); 1361 1362 if (unlikely(wo->wo_flags & WNOWAIT)) 1363 return wait_noreap_copyout(wo, p, pid, uid, why, exit_code); 1364 1365 retval = wo->wo_rusage 1366 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; 1367 if (!retval && wo->wo_stat) 1368 retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat); 1369 1370 infop = wo->wo_info; 1371 if (!retval && infop) 1372 retval = put_user(SIGCHLD, &infop->si_signo); 1373 if (!retval && infop) 1374 retval = put_user(0, &infop->si_errno); 1375 if (!retval && infop) 1376 retval = put_user((short)why, &infop->si_code); 1377 if (!retval && infop) 1378 retval = put_user(exit_code, &infop->si_status); 1379 if (!retval && infop) 1380 retval = put_user(pid, &infop->si_pid); 1381 if (!retval && infop) 1382 retval = put_user(uid, &infop->si_uid); 1383 if (!retval) 1384 retval = pid; 1385 put_task_struct(p); 1386 1387 BUG_ON(!retval); 1388 return retval; 1389 } 1390 1391 /* 1392 * Handle do_wait work for one task in a live, non-stopped state. 1393 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1394 * the lock and this task is uninteresting. If we return nonzero, we have 1395 * released the lock and the system call should return. 1396 */ 1397 static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) 1398 { 1399 int retval; 1400 pid_t pid; 1401 uid_t uid; 1402 1403 if (!unlikely(wo->wo_flags & WCONTINUED)) 1404 return 0; 1405 1406 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) 1407 return 0; 1408 1409 spin_lock_irq(&p->sighand->siglock); 1410 /* Re-check with the lock held. */ 1411 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { 1412 spin_unlock_irq(&p->sighand->siglock); 1413 return 0; 1414 } 1415 if (!unlikely(wo->wo_flags & WNOWAIT)) 1416 p->signal->flags &= ~SIGNAL_STOP_CONTINUED; 1417 uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1418 spin_unlock_irq(&p->sighand->siglock); 1419 1420 pid = task_pid_vnr(p); 1421 get_task_struct(p); 1422 read_unlock(&tasklist_lock); 1423 1424 if (!wo->wo_info) { 1425 retval = wo->wo_rusage 1426 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; 1427 put_task_struct(p); 1428 if (!retval && wo->wo_stat) 1429 retval = put_user(0xffff, wo->wo_stat); 1430 if (!retval) 1431 retval = pid; 1432 } else { 1433 retval = wait_noreap_copyout(wo, p, pid, uid, 1434 CLD_CONTINUED, SIGCONT); 1435 BUG_ON(retval == 0); 1436 } 1437 1438 return retval; 1439 } 1440 1441 /* 1442 * Consider @p for a wait by @parent. 1443 * 1444 * -ECHILD should be in ->notask_error before the first call. 1445 * Returns nonzero for a final return, when we have unlocked tasklist_lock. 1446 * Returns zero if the search for a child should continue; 1447 * then ->notask_error is 0 if @p is an eligible child, 1448 * or another error from security_task_wait(), or still -ECHILD. 1449 */ 1450 static int wait_consider_task(struct wait_opts *wo, int ptrace, 1451 struct task_struct *p) 1452 { 1453 int ret = eligible_child(wo, p); 1454 if (!ret) 1455 return ret; 1456 1457 ret = security_task_wait(p); 1458 if (unlikely(ret < 0)) { 1459 /* 1460 * If we have not yet seen any eligible child, 1461 * then let this error code replace -ECHILD. 1462 * A permission error will give the user a clue 1463 * to look for security policy problems, rather 1464 * than for mysterious wait bugs. 1465 */ 1466 if (wo->notask_error) 1467 wo->notask_error = ret; 1468 return 0; 1469 } 1470 1471 /* dead body doesn't have much to contribute */ 1472 if (unlikely(p->exit_state == EXIT_DEAD)) { 1473 /* 1474 * But do not ignore this task until the tracer does 1475 * wait_task_zombie()->do_notify_parent(). 1476 */ 1477 if (likely(!ptrace) && unlikely(ptrace_reparented(p))) 1478 wo->notask_error = 0; 1479 return 0; 1480 } 1481 1482 /* slay zombie? */ 1483 if (p->exit_state == EXIT_ZOMBIE) { 1484 /* 1485 * A zombie ptracee is only visible to its ptracer. 1486 * Notification and reaping will be cascaded to the real 1487 * parent when the ptracer detaches. 1488 */ 1489 if (likely(!ptrace) && unlikely(p->ptrace)) { 1490 /* it will become visible, clear notask_error */ 1491 wo->notask_error = 0; 1492 return 0; 1493 } 1494 1495 /* we don't reap group leaders with subthreads */ 1496 if (!delay_group_leader(p)) 1497 return wait_task_zombie(wo, p); 1498 1499 /* 1500 * Allow access to stopped/continued state via zombie by 1501 * falling through. Clearing of notask_error is complex. 1502 * 1503 * When !@ptrace: 1504 * 1505 * If WEXITED is set, notask_error should naturally be 1506 * cleared. If not, subset of WSTOPPED|WCONTINUED is set, 1507 * so, if there are live subthreads, there are events to 1508 * wait for. If all subthreads are dead, it's still safe 1509 * to clear - this function will be called again in finite 1510 * amount time once all the subthreads are released and 1511 * will then return without clearing. 1512 * 1513 * When @ptrace: 1514 * 1515 * Stopped state is per-task and thus can't change once the 1516 * target task dies. Only continued and exited can happen. 1517 * Clear notask_error if WCONTINUED | WEXITED. 1518 */ 1519 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED))) 1520 wo->notask_error = 0; 1521 } else { 1522 /* 1523 * If @p is ptraced by a task in its real parent's group, 1524 * hide group stop/continued state when looking at @p as 1525 * the real parent; otherwise, a single stop can be 1526 * reported twice as group and ptrace stops. 1527 * 1528 * If a ptracer wants to distinguish the two events for its 1529 * own children, it should create a separate process which 1530 * takes the role of real parent. 1531 */ 1532 if (likely(!ptrace) && p->ptrace && !ptrace_reparented(p)) 1533 return 0; 1534 1535 /* 1536 * @p is alive and it's gonna stop, continue or exit, so 1537 * there always is something to wait for. 1538 */ 1539 wo->notask_error = 0; 1540 } 1541 1542 /* 1543 * Wait for stopped. Depending on @ptrace, different stopped state 1544 * is used and the two don't interact with each other. 1545 */ 1546 ret = wait_task_stopped(wo, ptrace, p); 1547 if (ret) 1548 return ret; 1549 1550 /* 1551 * Wait for continued. There's only one continued state and the 1552 * ptracer can consume it which can confuse the real parent. Don't 1553 * use WCONTINUED from ptracer. You don't need or want it. 1554 */ 1555 return wait_task_continued(wo, p); 1556 } 1557 1558 /* 1559 * Do the work of do_wait() for one thread in the group, @tsk. 1560 * 1561 * -ECHILD should be in ->notask_error before the first call. 1562 * Returns nonzero for a final return, when we have unlocked tasklist_lock. 1563 * Returns zero if the search for a child should continue; then 1564 * ->notask_error is 0 if there were any eligible children, 1565 * or another error from security_task_wait(), or still -ECHILD. 1566 */ 1567 static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) 1568 { 1569 struct task_struct *p; 1570 1571 list_for_each_entry(p, &tsk->children, sibling) { 1572 int ret = wait_consider_task(wo, 0, p); 1573 if (ret) 1574 return ret; 1575 } 1576 1577 return 0; 1578 } 1579 1580 static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) 1581 { 1582 struct task_struct *p; 1583 1584 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { 1585 int ret = wait_consider_task(wo, 1, p); 1586 if (ret) 1587 return ret; 1588 } 1589 1590 return 0; 1591 } 1592 1593 static int child_wait_callback(wait_queue_t *wait, unsigned mode, 1594 int sync, void *key) 1595 { 1596 struct wait_opts *wo = container_of(wait, struct wait_opts, 1597 child_wait); 1598 struct task_struct *p = key; 1599 1600 if (!eligible_pid(wo, p)) 1601 return 0; 1602 1603 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) 1604 return 0; 1605 1606 return default_wake_function(wait, mode, sync, key); 1607 } 1608 1609 void __wake_up_parent(struct task_struct *p, struct task_struct *parent) 1610 { 1611 __wake_up_sync_key(&parent->signal->wait_chldexit, 1612 TASK_INTERRUPTIBLE, 1, p); 1613 } 1614 1615 static long do_wait(struct wait_opts *wo) 1616 { 1617 struct task_struct *tsk; 1618 int retval; 1619 1620 trace_sched_process_wait(wo->wo_pid); 1621 1622 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); 1623 wo->child_wait.private = current; 1624 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); 1625 repeat: 1626 /* 1627 * If there is nothing that can match our critiera just get out. 1628 * We will clear ->notask_error to zero if we see any child that 1629 * might later match our criteria, even if we are not able to reap 1630 * it yet. 1631 */ 1632 wo->notask_error = -ECHILD; 1633 if ((wo->wo_type < PIDTYPE_MAX) && 1634 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type]))) 1635 goto notask; 1636 1637 set_current_state(TASK_INTERRUPTIBLE); 1638 read_lock(&tasklist_lock); 1639 tsk = current; 1640 do { 1641 retval = do_wait_thread(wo, tsk); 1642 if (retval) 1643 goto end; 1644 1645 retval = ptrace_do_wait(wo, tsk); 1646 if (retval) 1647 goto end; 1648 1649 if (wo->wo_flags & __WNOTHREAD) 1650 break; 1651 } while_each_thread(current, tsk); 1652 read_unlock(&tasklist_lock); 1653 1654 notask: 1655 retval = wo->notask_error; 1656 if (!retval && !(wo->wo_flags & WNOHANG)) { 1657 retval = -ERESTARTSYS; 1658 if (!signal_pending(current)) { 1659 schedule(); 1660 goto repeat; 1661 } 1662 } 1663 end: 1664 __set_current_state(TASK_RUNNING); 1665 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); 1666 return retval; 1667 } 1668 1669 SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, 1670 infop, int, options, struct rusage __user *, ru) 1671 { 1672 struct wait_opts wo; 1673 struct pid *pid = NULL; 1674 enum pid_type type; 1675 long ret; 1676 1677 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED)) 1678 return -EINVAL; 1679 if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) 1680 return -EINVAL; 1681 1682 switch (which) { 1683 case P_ALL: 1684 type = PIDTYPE_MAX; 1685 break; 1686 case P_PID: 1687 type = PIDTYPE_PID; 1688 if (upid <= 0) 1689 return -EINVAL; 1690 break; 1691 case P_PGID: 1692 type = PIDTYPE_PGID; 1693 if (upid <= 0) 1694 return -EINVAL; 1695 break; 1696 default: 1697 return -EINVAL; 1698 } 1699 1700 if (type < PIDTYPE_MAX) 1701 pid = find_get_pid(upid); 1702 1703 wo.wo_type = type; 1704 wo.wo_pid = pid; 1705 wo.wo_flags = options; 1706 wo.wo_info = infop; 1707 wo.wo_stat = NULL; 1708 wo.wo_rusage = ru; 1709 ret = do_wait(&wo); 1710 1711 if (ret > 0) { 1712 ret = 0; 1713 } else if (infop) { 1714 /* 1715 * For a WNOHANG return, clear out all the fields 1716 * we would set so the user can easily tell the 1717 * difference. 1718 */ 1719 if (!ret) 1720 ret = put_user(0, &infop->si_signo); 1721 if (!ret) 1722 ret = put_user(0, &infop->si_errno); 1723 if (!ret) 1724 ret = put_user(0, &infop->si_code); 1725 if (!ret) 1726 ret = put_user(0, &infop->si_pid); 1727 if (!ret) 1728 ret = put_user(0, &infop->si_uid); 1729 if (!ret) 1730 ret = put_user(0, &infop->si_status); 1731 } 1732 1733 put_pid(pid); 1734 1735 /* avoid REGPARM breakage on x86: */ 1736 asmlinkage_protect(5, ret, which, upid, infop, options, ru); 1737 return ret; 1738 } 1739 1740 SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, 1741 int, options, struct rusage __user *, ru) 1742 { 1743 struct wait_opts wo; 1744 struct pid *pid = NULL; 1745 enum pid_type type; 1746 long ret; 1747 1748 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| 1749 __WNOTHREAD|__WCLONE|__WALL)) 1750 return -EINVAL; 1751 1752 if (upid == -1) 1753 type = PIDTYPE_MAX; 1754 else if (upid < 0) { 1755 type = PIDTYPE_PGID; 1756 pid = find_get_pid(-upid); 1757 } else if (upid == 0) { 1758 type = PIDTYPE_PGID; 1759 pid = get_task_pid(current, PIDTYPE_PGID); 1760 } else /* upid > 0 */ { 1761 type = PIDTYPE_PID; 1762 pid = find_get_pid(upid); 1763 } 1764 1765 wo.wo_type = type; 1766 wo.wo_pid = pid; 1767 wo.wo_flags = options | WEXITED; 1768 wo.wo_info = NULL; 1769 wo.wo_stat = stat_addr; 1770 wo.wo_rusage = ru; 1771 ret = do_wait(&wo); 1772 put_pid(pid); 1773 1774 /* avoid REGPARM breakage on x86: */ 1775 asmlinkage_protect(4, ret, upid, stat_addr, options, ru); 1776 return ret; 1777 } 1778 1779 #ifdef __ARCH_WANT_SYS_WAITPID 1780 1781 /* 1782 * sys_waitpid() remains for compatibility. waitpid() should be 1783 * implemented by calling sys_wait4() from libc.a. 1784 */ 1785 SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) 1786 { 1787 return sys_wait4(pid, stat_addr, options, NULL); 1788 } 1789 1790 #endif 1791