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 55 #include <asm/uaccess.h> 56 #include <asm/unistd.h> 57 #include <asm/pgtable.h> 58 #include <asm/mmu_context.h> 59 60 static void exit_mm(struct task_struct * tsk); 61 62 static void __unhash_process(struct task_struct *p, bool group_dead) 63 { 64 nr_threads--; 65 detach_pid(p, PIDTYPE_PID); 66 if (group_dead) { 67 detach_pid(p, PIDTYPE_PGID); 68 detach_pid(p, PIDTYPE_SID); 69 70 list_del_rcu(&p->tasks); 71 list_del_init(&p->sibling); 72 __this_cpu_dec(process_counts); 73 } 74 list_del_rcu(&p->thread_group); 75 } 76 77 /* 78 * This function expects the tasklist_lock write-locked. 79 */ 80 static void __exit_signal(struct task_struct *tsk) 81 { 82 struct signal_struct *sig = tsk->signal; 83 bool group_dead = thread_group_leader(tsk); 84 struct sighand_struct *sighand; 85 struct tty_struct *uninitialized_var(tty); 86 87 sighand = rcu_dereference_check(tsk->sighand, 88 rcu_read_lock_held() || 89 lockdep_tasklist_lock_is_held()); 90 spin_lock(&sighand->siglock); 91 92 posix_cpu_timers_exit(tsk); 93 if (group_dead) { 94 posix_cpu_timers_exit_group(tsk); 95 tty = sig->tty; 96 sig->tty = NULL; 97 } else { 98 /* 99 * This can only happen if the caller is de_thread(). 100 * FIXME: this is the temporary hack, we should teach 101 * posix-cpu-timers to handle this case correctly. 102 */ 103 if (unlikely(has_group_leader_pid(tsk))) 104 posix_cpu_timers_exit_group(tsk); 105 106 /* 107 * If there is any task waiting for the group exit 108 * then notify it: 109 */ 110 if (sig->notify_count > 0 && !--sig->notify_count) 111 wake_up_process(sig->group_exit_task); 112 113 if (tsk == sig->curr_target) 114 sig->curr_target = next_thread(tsk); 115 /* 116 * Accumulate here the counters for all threads but the 117 * group leader as they die, so they can be added into 118 * the process-wide totals when those are taken. 119 * The group leader stays around as a zombie as long 120 * as there are other threads. When it gets reaped, 121 * the exit.c code will add its counts into these totals. 122 * We won't ever get here for the group leader, since it 123 * will have been the last reference on the signal_struct. 124 */ 125 sig->utime = cputime_add(sig->utime, tsk->utime); 126 sig->stime = cputime_add(sig->stime, tsk->stime); 127 sig->gtime = cputime_add(sig->gtime, tsk->gtime); 128 sig->min_flt += tsk->min_flt; 129 sig->maj_flt += tsk->maj_flt; 130 sig->nvcsw += tsk->nvcsw; 131 sig->nivcsw += tsk->nivcsw; 132 sig->inblock += task_io_get_inblock(tsk); 133 sig->oublock += task_io_get_oublock(tsk); 134 task_io_accounting_add(&sig->ioac, &tsk->ioac); 135 sig->sum_sched_runtime += tsk->se.sum_exec_runtime; 136 } 137 138 sig->nr_threads--; 139 __unhash_process(tsk, group_dead); 140 141 /* 142 * Do this under ->siglock, we can race with another thread 143 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. 144 */ 145 flush_sigqueue(&tsk->pending); 146 tsk->sighand = NULL; 147 spin_unlock(&sighand->siglock); 148 149 __cleanup_sighand(sighand); 150 clear_tsk_thread_flag(tsk,TIF_SIGPENDING); 151 if (group_dead) { 152 flush_sigqueue(&sig->shared_pending); 153 tty_kref_put(tty); 154 } 155 } 156 157 static void delayed_put_task_struct(struct rcu_head *rhp) 158 { 159 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); 160 161 perf_event_delayed_put(tsk); 162 trace_sched_process_free(tsk); 163 put_task_struct(tsk); 164 } 165 166 167 void release_task(struct task_struct * p) 168 { 169 struct task_struct *leader; 170 int zap_leader; 171 repeat: 172 tracehook_prepare_release_task(p); 173 /* don't need to get the RCU readlock here - the process is dead and 174 * can't be modifying its own credentials. But shut RCU-lockdep up */ 175 rcu_read_lock(); 176 atomic_dec(&__task_cred(p)->user->processes); 177 rcu_read_unlock(); 178 179 proc_flush_task(p); 180 181 write_lock_irq(&tasklist_lock); 182 tracehook_finish_release_task(p); 183 __exit_signal(p); 184 185 /* 186 * If we are the last non-leader member of the thread 187 * group, and the leader is zombie, then notify the 188 * group leader's parent process. (if it wants notification.) 189 */ 190 zap_leader = 0; 191 leader = p->group_leader; 192 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) { 193 BUG_ON(task_detached(leader)); 194 do_notify_parent(leader, leader->exit_signal); 195 /* 196 * If we were the last child thread and the leader has 197 * exited already, and the leader's parent ignores SIGCHLD, 198 * then we are the one who should release the leader. 199 * 200 * do_notify_parent() will have marked it self-reaping in 201 * that case. 202 */ 203 zap_leader = task_detached(leader); 204 205 /* 206 * This maintains the invariant that release_task() 207 * only runs on a task in EXIT_DEAD, just for sanity. 208 */ 209 if (zap_leader) 210 leader->exit_state = EXIT_DEAD; 211 } 212 213 write_unlock_irq(&tasklist_lock); 214 release_thread(p); 215 call_rcu(&p->rcu, delayed_put_task_struct); 216 217 p = leader; 218 if (unlikely(zap_leader)) 219 goto repeat; 220 } 221 222 /* 223 * This checks not only the pgrp, but falls back on the pid if no 224 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly 225 * without this... 226 * 227 * The caller must hold rcu lock or the tasklist lock. 228 */ 229 struct pid *session_of_pgrp(struct pid *pgrp) 230 { 231 struct task_struct *p; 232 struct pid *sid = NULL; 233 234 p = pid_task(pgrp, PIDTYPE_PGID); 235 if (p == NULL) 236 p = pid_task(pgrp, PIDTYPE_PID); 237 if (p != NULL) 238 sid = task_session(p); 239 240 return sid; 241 } 242 243 /* 244 * Determine if a process group is "orphaned", according to the POSIX 245 * definition in 2.2.2.52. Orphaned process groups are not to be affected 246 * by terminal-generated stop signals. Newly orphaned process groups are 247 * to receive a SIGHUP and a SIGCONT. 248 * 249 * "I ask you, have you ever known what it is to be an orphan?" 250 */ 251 static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task) 252 { 253 struct task_struct *p; 254 255 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 256 if ((p == ignored_task) || 257 (p->exit_state && thread_group_empty(p)) || 258 is_global_init(p->real_parent)) 259 continue; 260 261 if (task_pgrp(p->real_parent) != pgrp && 262 task_session(p->real_parent) == task_session(p)) 263 return 0; 264 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 265 266 return 1; 267 } 268 269 int is_current_pgrp_orphaned(void) 270 { 271 int retval; 272 273 read_lock(&tasklist_lock); 274 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); 275 read_unlock(&tasklist_lock); 276 277 return retval; 278 } 279 280 static int has_stopped_jobs(struct pid *pgrp) 281 { 282 int retval = 0; 283 struct task_struct *p; 284 285 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 286 if (!task_is_stopped(p)) 287 continue; 288 retval = 1; 289 break; 290 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 291 return retval; 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 have TIF_FREEZE set if the 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 exit_files(current); 461 current->files = init_task.files; 462 atomic_inc(¤t->files->count); 463 464 reparent_to_kthreadd(); 465 } 466 467 EXPORT_SYMBOL(daemonize); 468 469 static void close_files(struct files_struct * files) 470 { 471 int i, j; 472 struct fdtable *fdt; 473 474 j = 0; 475 476 /* 477 * It is safe to dereference the fd table without RCU or 478 * ->file_lock because this is the last reference to the 479 * files structure. But use RCU to shut RCU-lockdep up. 480 */ 481 rcu_read_lock(); 482 fdt = files_fdtable(files); 483 rcu_read_unlock(); 484 for (;;) { 485 unsigned long set; 486 i = j * __NFDBITS; 487 if (i >= fdt->max_fds) 488 break; 489 set = fdt->open_fds->fds_bits[j++]; 490 while (set) { 491 if (set & 1) { 492 struct file * file = xchg(&fdt->fd[i], NULL); 493 if (file) { 494 filp_close(file, files); 495 cond_resched(); 496 } 497 } 498 i++; 499 set >>= 1; 500 } 501 } 502 } 503 504 struct files_struct *get_files_struct(struct task_struct *task) 505 { 506 struct files_struct *files; 507 508 task_lock(task); 509 files = task->files; 510 if (files) 511 atomic_inc(&files->count); 512 task_unlock(task); 513 514 return files; 515 } 516 517 void put_files_struct(struct files_struct *files) 518 { 519 struct fdtable *fdt; 520 521 if (atomic_dec_and_test(&files->count)) { 522 close_files(files); 523 /* 524 * Free the fd and fdset arrays if we expanded them. 525 * If the fdtable was embedded, pass files for freeing 526 * at the end of the RCU grace period. Otherwise, 527 * you can free files immediately. 528 */ 529 rcu_read_lock(); 530 fdt = files_fdtable(files); 531 if (fdt != &files->fdtab) 532 kmem_cache_free(files_cachep, files); 533 free_fdtable(fdt); 534 rcu_read_unlock(); 535 } 536 } 537 538 void reset_files_struct(struct files_struct *files) 539 { 540 struct task_struct *tsk = current; 541 struct files_struct *old; 542 543 old = tsk->files; 544 task_lock(tsk); 545 tsk->files = files; 546 task_unlock(tsk); 547 put_files_struct(old); 548 } 549 550 void exit_files(struct task_struct *tsk) 551 { 552 struct files_struct * files = tsk->files; 553 554 if (files) { 555 task_lock(tsk); 556 tsk->files = NULL; 557 task_unlock(tsk); 558 put_files_struct(files); 559 } 560 } 561 562 #ifdef CONFIG_MM_OWNER 563 /* 564 * Task p is exiting and it owned mm, lets find a new owner for it 565 */ 566 static inline int 567 mm_need_new_owner(struct mm_struct *mm, struct task_struct *p) 568 { 569 /* 570 * If there are other users of the mm and the owner (us) is exiting 571 * we need to find a new owner to take on the responsibility. 572 */ 573 if (atomic_read(&mm->mm_users) <= 1) 574 return 0; 575 if (mm->owner != p) 576 return 0; 577 return 1; 578 } 579 580 void mm_update_next_owner(struct mm_struct *mm) 581 { 582 struct task_struct *c, *g, *p = current; 583 584 retry: 585 if (!mm_need_new_owner(mm, p)) 586 return; 587 588 read_lock(&tasklist_lock); 589 /* 590 * Search in the children 591 */ 592 list_for_each_entry(c, &p->children, sibling) { 593 if (c->mm == mm) 594 goto assign_new_owner; 595 } 596 597 /* 598 * Search in the siblings 599 */ 600 list_for_each_entry(c, &p->real_parent->children, sibling) { 601 if (c->mm == mm) 602 goto assign_new_owner; 603 } 604 605 /* 606 * Search through everything else. We should not get 607 * here often 608 */ 609 do_each_thread(g, c) { 610 if (c->mm == mm) 611 goto assign_new_owner; 612 } while_each_thread(g, c); 613 614 read_unlock(&tasklist_lock); 615 /* 616 * We found no owner yet mm_users > 1: this implies that we are 617 * most likely racing with swapoff (try_to_unuse()) or /proc or 618 * ptrace or page migration (get_task_mm()). Mark owner as NULL. 619 */ 620 mm->owner = NULL; 621 return; 622 623 assign_new_owner: 624 BUG_ON(c == p); 625 get_task_struct(c); 626 /* 627 * The task_lock protects c->mm from changing. 628 * We always want mm->owner->mm == mm 629 */ 630 task_lock(c); 631 /* 632 * Delay read_unlock() till we have the task_lock() 633 * to ensure that c does not slip away underneath us 634 */ 635 read_unlock(&tasklist_lock); 636 if (c->mm != mm) { 637 task_unlock(c); 638 put_task_struct(c); 639 goto retry; 640 } 641 mm->owner = c; 642 task_unlock(c); 643 put_task_struct(c); 644 } 645 #endif /* CONFIG_MM_OWNER */ 646 647 /* 648 * Turn us into a lazy TLB process if we 649 * aren't already.. 650 */ 651 static void exit_mm(struct task_struct * tsk) 652 { 653 struct mm_struct *mm = tsk->mm; 654 struct core_state *core_state; 655 656 mm_release(tsk, mm); 657 if (!mm) 658 return; 659 /* 660 * Serialize with any possible pending coredump. 661 * We must hold mmap_sem around checking core_state 662 * and clearing tsk->mm. The core-inducing thread 663 * will increment ->nr_threads for each thread in the 664 * group with ->mm != NULL. 665 */ 666 down_read(&mm->mmap_sem); 667 core_state = mm->core_state; 668 if (core_state) { 669 struct core_thread self; 670 up_read(&mm->mmap_sem); 671 672 self.task = tsk; 673 self.next = xchg(&core_state->dumper.next, &self); 674 /* 675 * Implies mb(), the result of xchg() must be visible 676 * to core_state->dumper. 677 */ 678 if (atomic_dec_and_test(&core_state->nr_threads)) 679 complete(&core_state->startup); 680 681 for (;;) { 682 set_task_state(tsk, TASK_UNINTERRUPTIBLE); 683 if (!self.task) /* see coredump_finish() */ 684 break; 685 schedule(); 686 } 687 __set_task_state(tsk, TASK_RUNNING); 688 down_read(&mm->mmap_sem); 689 } 690 atomic_inc(&mm->mm_count); 691 BUG_ON(mm != tsk->active_mm); 692 /* more a memory barrier than a real lock */ 693 task_lock(tsk); 694 tsk->mm = NULL; 695 up_read(&mm->mmap_sem); 696 enter_lazy_tlb(mm, current); 697 /* We don't want this task to be frozen prematurely */ 698 clear_freeze_flag(tsk); 699 if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) 700 atomic_dec(&mm->oom_disable_count); 701 task_unlock(tsk); 702 mm_update_next_owner(mm); 703 mmput(mm); 704 } 705 706 /* 707 * When we die, we re-parent all our children. 708 * Try to give them to another thread in our thread 709 * group, and if no such member exists, give it to 710 * the child reaper process (ie "init") in our pid 711 * space. 712 */ 713 static struct task_struct *find_new_reaper(struct task_struct *father) 714 __releases(&tasklist_lock) 715 __acquires(&tasklist_lock) 716 { 717 struct pid_namespace *pid_ns = task_active_pid_ns(father); 718 struct task_struct *thread; 719 720 thread = father; 721 while_each_thread(father, thread) { 722 if (thread->flags & PF_EXITING) 723 continue; 724 if (unlikely(pid_ns->child_reaper == father)) 725 pid_ns->child_reaper = thread; 726 return thread; 727 } 728 729 if (unlikely(pid_ns->child_reaper == father)) { 730 write_unlock_irq(&tasklist_lock); 731 if (unlikely(pid_ns == &init_pid_ns)) 732 panic("Attempted to kill init!"); 733 734 zap_pid_ns_processes(pid_ns); 735 write_lock_irq(&tasklist_lock); 736 /* 737 * We can not clear ->child_reaper or leave it alone. 738 * There may by stealth EXIT_DEAD tasks on ->children, 739 * forget_original_parent() must move them somewhere. 740 */ 741 pid_ns->child_reaper = init_pid_ns.child_reaper; 742 } 743 744 return pid_ns->child_reaper; 745 } 746 747 /* 748 * Any that need to be release_task'd are put on the @dead list. 749 */ 750 static void reparent_leader(struct task_struct *father, struct task_struct *p, 751 struct list_head *dead) 752 { 753 list_move_tail(&p->sibling, &p->real_parent->children); 754 755 if (task_detached(p)) 756 return; 757 /* 758 * If this is a threaded reparent there is no need to 759 * notify anyone anything has happened. 760 */ 761 if (same_thread_group(p->real_parent, father)) 762 return; 763 764 /* We don't want people slaying init. */ 765 p->exit_signal = SIGCHLD; 766 767 /* If it has exited notify the new parent about this child's death. */ 768 if (!task_ptrace(p) && 769 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { 770 do_notify_parent(p, p->exit_signal); 771 if (task_detached(p)) { 772 p->exit_state = EXIT_DEAD; 773 list_move_tail(&p->sibling, dead); 774 } 775 } 776 777 kill_orphaned_pgrp(p, father); 778 } 779 780 static void forget_original_parent(struct task_struct *father) 781 { 782 struct task_struct *p, *n, *reaper; 783 LIST_HEAD(dead_children); 784 785 write_lock_irq(&tasklist_lock); 786 /* 787 * Note that exit_ptrace() and find_new_reaper() might 788 * drop tasklist_lock and reacquire it. 789 */ 790 exit_ptrace(father); 791 reaper = find_new_reaper(father); 792 793 list_for_each_entry_safe(p, n, &father->children, sibling) { 794 struct task_struct *t = p; 795 do { 796 t->real_parent = reaper; 797 if (t->parent == father) { 798 BUG_ON(task_ptrace(t)); 799 t->parent = t->real_parent; 800 } 801 if (t->pdeath_signal) 802 group_send_sig_info(t->pdeath_signal, 803 SEND_SIG_NOINFO, t); 804 } while_each_thread(p, t); 805 reparent_leader(father, p, &dead_children); 806 } 807 write_unlock_irq(&tasklist_lock); 808 809 BUG_ON(!list_empty(&father->children)); 810 811 list_for_each_entry_safe(p, n, &dead_children, sibling) { 812 list_del_init(&p->sibling); 813 release_task(p); 814 } 815 } 816 817 /* 818 * Send signals to all our closest relatives so that they know 819 * to properly mourn us.. 820 */ 821 static void exit_notify(struct task_struct *tsk, int group_dead) 822 { 823 int signal; 824 void *cookie; 825 826 /* 827 * This does two things: 828 * 829 * A. Make init inherit all the child processes 830 * B. Check to see if any process groups have become orphaned 831 * as a result of our exiting, and if they have any stopped 832 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 833 */ 834 forget_original_parent(tsk); 835 exit_task_namespaces(tsk); 836 837 write_lock_irq(&tasklist_lock); 838 if (group_dead) 839 kill_orphaned_pgrp(tsk->group_leader, NULL); 840 841 /* Let father know we died 842 * 843 * Thread signals are configurable, but you aren't going to use 844 * that to send signals to arbitary processes. 845 * That stops right now. 846 * 847 * If the parent exec id doesn't match the exec id we saved 848 * when we started then we know the parent has changed security 849 * domain. 850 * 851 * If our self_exec id doesn't match our parent_exec_id then 852 * we have changed execution domain as these two values started 853 * the same after a fork. 854 */ 855 if (tsk->exit_signal != SIGCHLD && !task_detached(tsk) && 856 (tsk->parent_exec_id != tsk->real_parent->self_exec_id || 857 tsk->self_exec_id != tsk->parent_exec_id)) 858 tsk->exit_signal = SIGCHLD; 859 860 signal = tracehook_notify_death(tsk, &cookie, group_dead); 861 if (signal >= 0) 862 signal = do_notify_parent(tsk, signal); 863 864 tsk->exit_state = signal == DEATH_REAP ? EXIT_DEAD : EXIT_ZOMBIE; 865 866 /* mt-exec, de_thread() is waiting for group leader */ 867 if (unlikely(tsk->signal->notify_count < 0)) 868 wake_up_process(tsk->signal->group_exit_task); 869 write_unlock_irq(&tasklist_lock); 870 871 tracehook_report_death(tsk, signal, cookie, group_dead); 872 873 /* If the process is dead, release it - nobody will wait for it */ 874 if (signal == DEATH_REAP) 875 release_task(tsk); 876 } 877 878 #ifdef CONFIG_DEBUG_STACK_USAGE 879 static void check_stack_usage(void) 880 { 881 static DEFINE_SPINLOCK(low_water_lock); 882 static int lowest_to_date = THREAD_SIZE; 883 unsigned long free; 884 885 free = stack_not_used(current); 886 887 if (free >= lowest_to_date) 888 return; 889 890 spin_lock(&low_water_lock); 891 if (free < lowest_to_date) { 892 printk(KERN_WARNING "%s used greatest stack depth: %lu bytes " 893 "left\n", 894 current->comm, free); 895 lowest_to_date = free; 896 } 897 spin_unlock(&low_water_lock); 898 } 899 #else 900 static inline void check_stack_usage(void) {} 901 #endif 902 903 NORET_TYPE void do_exit(long code) 904 { 905 struct task_struct *tsk = current; 906 int group_dead; 907 908 profile_task_exit(tsk); 909 910 WARN_ON(atomic_read(&tsk->fs_excl)); 911 912 if (unlikely(in_interrupt())) 913 panic("Aiee, killing interrupt handler!"); 914 if (unlikely(!tsk->pid)) 915 panic("Attempted to kill the idle task!"); 916 917 /* 918 * If do_exit is called because this processes oopsed, it's possible 919 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before 920 * continuing. Amongst other possible reasons, this is to prevent 921 * mm_release()->clear_child_tid() from writing to a user-controlled 922 * kernel address. 923 */ 924 set_fs(USER_DS); 925 926 tracehook_report_exit(&code); 927 928 validate_creds_for_do_exit(tsk); 929 930 /* 931 * We're taking recursive faults here in do_exit. Safest is to just 932 * leave this task alone and wait for reboot. 933 */ 934 if (unlikely(tsk->flags & PF_EXITING)) { 935 printk(KERN_ALERT 936 "Fixing recursive fault but reboot is needed!\n"); 937 /* 938 * We can do this unlocked here. The futex code uses 939 * this flag just to verify whether the pi state 940 * cleanup has been done or not. In the worst case it 941 * loops once more. We pretend that the cleanup was 942 * done as there is no way to return. Either the 943 * OWNER_DIED bit is set by now or we push the blocked 944 * task into the wait for ever nirwana as well. 945 */ 946 tsk->flags |= PF_EXITPIDONE; 947 set_current_state(TASK_UNINTERRUPTIBLE); 948 schedule(); 949 } 950 951 exit_irq_thread(); 952 953 exit_signals(tsk); /* sets PF_EXITING */ 954 /* 955 * tsk->flags are checked in the futex code to protect against 956 * an exiting task cleaning up the robust pi futexes. 957 */ 958 smp_mb(); 959 raw_spin_unlock_wait(&tsk->pi_lock); 960 961 if (unlikely(in_atomic())) 962 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n", 963 current->comm, task_pid_nr(current), 964 preempt_count()); 965 966 acct_update_integrals(tsk); 967 /* sync mm's RSS info before statistics gathering */ 968 if (tsk->mm) 969 sync_mm_rss(tsk, tsk->mm); 970 group_dead = atomic_dec_and_test(&tsk->signal->live); 971 if (group_dead) { 972 hrtimer_cancel(&tsk->signal->real_timer); 973 exit_itimers(tsk->signal); 974 if (tsk->mm) 975 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); 976 } 977 acct_collect(code, group_dead); 978 if (group_dead) 979 tty_audit_exit(); 980 if (unlikely(tsk->audit_context)) 981 audit_free(tsk); 982 983 tsk->exit_code = code; 984 taskstats_exit(tsk, group_dead); 985 986 exit_mm(tsk); 987 988 if (group_dead) 989 acct_process(); 990 trace_sched_process_exit(tsk); 991 992 exit_sem(tsk); 993 exit_files(tsk); 994 exit_fs(tsk); 995 check_stack_usage(); 996 exit_thread(); 997 998 /* 999 * Flush inherited counters to the parent - before the parent 1000 * gets woken up by child-exit notifications. 1001 * 1002 * because of cgroup mode, must be called before cgroup_exit() 1003 */ 1004 perf_event_exit_task(tsk); 1005 1006 cgroup_exit(tsk, 1); 1007 1008 if (group_dead) 1009 disassociate_ctty(1); 1010 1011 module_put(task_thread_info(tsk)->exec_domain->module); 1012 1013 proc_exit_connector(tsk); 1014 1015 /* 1016 * FIXME: do that only when needed, using sched_exit tracepoint 1017 */ 1018 flush_ptrace_hw_breakpoint(tsk); 1019 1020 exit_notify(tsk, group_dead); 1021 #ifdef CONFIG_NUMA 1022 task_lock(tsk); 1023 mpol_put(tsk->mempolicy); 1024 tsk->mempolicy = NULL; 1025 task_unlock(tsk); 1026 #endif 1027 #ifdef CONFIG_FUTEX 1028 if (unlikely(current->pi_state_cache)) 1029 kfree(current->pi_state_cache); 1030 #endif 1031 /* 1032 * Make sure we are holding no locks: 1033 */ 1034 debug_check_no_locks_held(tsk); 1035 /* 1036 * We can do this unlocked here. The futex code uses this flag 1037 * just to verify whether the pi state cleanup has been done 1038 * or not. In the worst case it loops once more. 1039 */ 1040 tsk->flags |= PF_EXITPIDONE; 1041 1042 if (tsk->io_context) 1043 exit_io_context(tsk); 1044 1045 if (tsk->splice_pipe) 1046 __free_pipe_info(tsk->splice_pipe); 1047 1048 validate_creds_for_do_exit(tsk); 1049 1050 preempt_disable(); 1051 exit_rcu(); 1052 /* causes final put_task_struct in finish_task_switch(). */ 1053 tsk->state = TASK_DEAD; 1054 schedule(); 1055 BUG(); 1056 /* Avoid "noreturn function does return". */ 1057 for (;;) 1058 cpu_relax(); /* For when BUG is null */ 1059 } 1060 1061 EXPORT_SYMBOL_GPL(do_exit); 1062 1063 NORET_TYPE void complete_and_exit(struct completion *comp, long code) 1064 { 1065 if (comp) 1066 complete(comp); 1067 1068 do_exit(code); 1069 } 1070 1071 EXPORT_SYMBOL(complete_and_exit); 1072 1073 SYSCALL_DEFINE1(exit, int, error_code) 1074 { 1075 do_exit((error_code&0xff)<<8); 1076 } 1077 1078 /* 1079 * Take down every thread in the group. This is called by fatal signals 1080 * as well as by sys_exit_group (below). 1081 */ 1082 NORET_TYPE void 1083 do_group_exit(int exit_code) 1084 { 1085 struct signal_struct *sig = current->signal; 1086 1087 BUG_ON(exit_code & 0x80); /* core dumps don't get here */ 1088 1089 if (signal_group_exit(sig)) 1090 exit_code = sig->group_exit_code; 1091 else if (!thread_group_empty(current)) { 1092 struct sighand_struct *const sighand = current->sighand; 1093 spin_lock_irq(&sighand->siglock); 1094 if (signal_group_exit(sig)) 1095 /* Another thread got here before we took the lock. */ 1096 exit_code = sig->group_exit_code; 1097 else { 1098 sig->group_exit_code = exit_code; 1099 sig->flags = SIGNAL_GROUP_EXIT; 1100 zap_other_threads(current); 1101 } 1102 spin_unlock_irq(&sighand->siglock); 1103 } 1104 1105 do_exit(exit_code); 1106 /* NOTREACHED */ 1107 } 1108 1109 /* 1110 * this kills every thread in the thread group. Note that any externally 1111 * wait4()-ing process will get the correct exit code - even if this 1112 * thread is not the thread group leader. 1113 */ 1114 SYSCALL_DEFINE1(exit_group, int, error_code) 1115 { 1116 do_group_exit((error_code & 0xff) << 8); 1117 /* NOTREACHED */ 1118 return 0; 1119 } 1120 1121 struct wait_opts { 1122 enum pid_type wo_type; 1123 int wo_flags; 1124 struct pid *wo_pid; 1125 1126 struct siginfo __user *wo_info; 1127 int __user *wo_stat; 1128 struct rusage __user *wo_rusage; 1129 1130 wait_queue_t child_wait; 1131 int notask_error; 1132 }; 1133 1134 static inline 1135 struct pid *task_pid_type(struct task_struct *task, enum pid_type type) 1136 { 1137 if (type != PIDTYPE_PID) 1138 task = task->group_leader; 1139 return task->pids[type].pid; 1140 } 1141 1142 static int eligible_pid(struct wait_opts *wo, struct task_struct *p) 1143 { 1144 return wo->wo_type == PIDTYPE_MAX || 1145 task_pid_type(p, wo->wo_type) == wo->wo_pid; 1146 } 1147 1148 static int eligible_child(struct wait_opts *wo, struct task_struct *p) 1149 { 1150 if (!eligible_pid(wo, p)) 1151 return 0; 1152 /* Wait for all children (clone and not) if __WALL is set; 1153 * otherwise, wait for clone children *only* if __WCLONE is 1154 * set; otherwise, wait for non-clone children *only*. (Note: 1155 * A "clone" child here is one that reports to its parent 1156 * using a signal other than SIGCHLD.) */ 1157 if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) 1158 && !(wo->wo_flags & __WALL)) 1159 return 0; 1160 1161 return 1; 1162 } 1163 1164 static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p, 1165 pid_t pid, uid_t uid, int why, int status) 1166 { 1167 struct siginfo __user *infop; 1168 int retval = wo->wo_rusage 1169 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; 1170 1171 put_task_struct(p); 1172 infop = wo->wo_info; 1173 if (infop) { 1174 if (!retval) 1175 retval = put_user(SIGCHLD, &infop->si_signo); 1176 if (!retval) 1177 retval = put_user(0, &infop->si_errno); 1178 if (!retval) 1179 retval = put_user((short)why, &infop->si_code); 1180 if (!retval) 1181 retval = put_user(pid, &infop->si_pid); 1182 if (!retval) 1183 retval = put_user(uid, &infop->si_uid); 1184 if (!retval) 1185 retval = put_user(status, &infop->si_status); 1186 } 1187 if (!retval) 1188 retval = pid; 1189 return retval; 1190 } 1191 1192 /* 1193 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold 1194 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1195 * the lock and this task is uninteresting. If we return nonzero, we have 1196 * released the lock and the system call should return. 1197 */ 1198 static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) 1199 { 1200 unsigned long state; 1201 int retval, status, traced; 1202 pid_t pid = task_pid_vnr(p); 1203 uid_t uid = __task_cred(p)->uid; 1204 struct siginfo __user *infop; 1205 1206 if (!likely(wo->wo_flags & WEXITED)) 1207 return 0; 1208 1209 if (unlikely(wo->wo_flags & WNOWAIT)) { 1210 int exit_code = p->exit_code; 1211 int why; 1212 1213 get_task_struct(p); 1214 read_unlock(&tasklist_lock); 1215 if ((exit_code & 0x7f) == 0) { 1216 why = CLD_EXITED; 1217 status = exit_code >> 8; 1218 } else { 1219 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED; 1220 status = exit_code & 0x7f; 1221 } 1222 return wait_noreap_copyout(wo, p, pid, uid, why, status); 1223 } 1224 1225 /* 1226 * Try to move the task's state to DEAD 1227 * only one thread is allowed to do this: 1228 */ 1229 state = xchg(&p->exit_state, EXIT_DEAD); 1230 if (state != EXIT_ZOMBIE) { 1231 BUG_ON(state != EXIT_DEAD); 1232 return 0; 1233 } 1234 1235 traced = ptrace_reparented(p); 1236 /* 1237 * It can be ptraced but not reparented, check 1238 * !task_detached() to filter out sub-threads. 1239 */ 1240 if (likely(!traced) && likely(!task_detached(p))) { 1241 struct signal_struct *psig; 1242 struct signal_struct *sig; 1243 unsigned long maxrss; 1244 cputime_t tgutime, tgstime; 1245 1246 /* 1247 * The resource counters for the group leader are in its 1248 * own task_struct. Those for dead threads in the group 1249 * are in its signal_struct, as are those for the child 1250 * processes it has previously reaped. All these 1251 * accumulate in the parent's signal_struct c* fields. 1252 * 1253 * We don't bother to take a lock here to protect these 1254 * p->signal fields, because they are only touched by 1255 * __exit_signal, which runs with tasklist_lock 1256 * write-locked anyway, and so is excluded here. We do 1257 * need to protect the access to parent->signal fields, 1258 * as other threads in the parent group can be right 1259 * here reaping other children at the same time. 1260 * 1261 * We use thread_group_times() to get times for the thread 1262 * group, which consolidates times for all threads in the 1263 * group including the group leader. 1264 */ 1265 thread_group_times(p, &tgutime, &tgstime); 1266 spin_lock_irq(&p->real_parent->sighand->siglock); 1267 psig = p->real_parent->signal; 1268 sig = p->signal; 1269 psig->cutime = 1270 cputime_add(psig->cutime, 1271 cputime_add(tgutime, 1272 sig->cutime)); 1273 psig->cstime = 1274 cputime_add(psig->cstime, 1275 cputime_add(tgstime, 1276 sig->cstime)); 1277 psig->cgtime = 1278 cputime_add(psig->cgtime, 1279 cputime_add(p->gtime, 1280 cputime_add(sig->gtime, 1281 sig->cgtime))); 1282 psig->cmin_flt += 1283 p->min_flt + sig->min_flt + sig->cmin_flt; 1284 psig->cmaj_flt += 1285 p->maj_flt + sig->maj_flt + sig->cmaj_flt; 1286 psig->cnvcsw += 1287 p->nvcsw + sig->nvcsw + sig->cnvcsw; 1288 psig->cnivcsw += 1289 p->nivcsw + sig->nivcsw + sig->cnivcsw; 1290 psig->cinblock += 1291 task_io_get_inblock(p) + 1292 sig->inblock + sig->cinblock; 1293 psig->coublock += 1294 task_io_get_oublock(p) + 1295 sig->oublock + sig->coublock; 1296 maxrss = max(sig->maxrss, sig->cmaxrss); 1297 if (psig->cmaxrss < maxrss) 1298 psig->cmaxrss = maxrss; 1299 task_io_accounting_add(&psig->ioac, &p->ioac); 1300 task_io_accounting_add(&psig->ioac, &sig->ioac); 1301 spin_unlock_irq(&p->real_parent->sighand->siglock); 1302 } 1303 1304 /* 1305 * Now we are sure this task is interesting, and no other 1306 * thread can reap it because we set its state to EXIT_DEAD. 1307 */ 1308 read_unlock(&tasklist_lock); 1309 1310 retval = wo->wo_rusage 1311 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; 1312 status = (p->signal->flags & SIGNAL_GROUP_EXIT) 1313 ? p->signal->group_exit_code : p->exit_code; 1314 if (!retval && wo->wo_stat) 1315 retval = put_user(status, wo->wo_stat); 1316 1317 infop = wo->wo_info; 1318 if (!retval && infop) 1319 retval = put_user(SIGCHLD, &infop->si_signo); 1320 if (!retval && infop) 1321 retval = put_user(0, &infop->si_errno); 1322 if (!retval && infop) { 1323 int why; 1324 1325 if ((status & 0x7f) == 0) { 1326 why = CLD_EXITED; 1327 status >>= 8; 1328 } else { 1329 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; 1330 status &= 0x7f; 1331 } 1332 retval = put_user((short)why, &infop->si_code); 1333 if (!retval) 1334 retval = put_user(status, &infop->si_status); 1335 } 1336 if (!retval && infop) 1337 retval = put_user(pid, &infop->si_pid); 1338 if (!retval && infop) 1339 retval = put_user(uid, &infop->si_uid); 1340 if (!retval) 1341 retval = pid; 1342 1343 if (traced) { 1344 write_lock_irq(&tasklist_lock); 1345 /* We dropped tasklist, ptracer could die and untrace */ 1346 ptrace_unlink(p); 1347 /* 1348 * If this is not a detached task, notify the parent. 1349 * If it's still not detached after that, don't release 1350 * it now. 1351 */ 1352 if (!task_detached(p)) { 1353 do_notify_parent(p, p->exit_signal); 1354 if (!task_detached(p)) { 1355 p->exit_state = EXIT_ZOMBIE; 1356 p = NULL; 1357 } 1358 } 1359 write_unlock_irq(&tasklist_lock); 1360 } 1361 if (p != NULL) 1362 release_task(p); 1363 1364 return retval; 1365 } 1366 1367 static int *task_stopped_code(struct task_struct *p, bool ptrace) 1368 { 1369 if (ptrace) { 1370 if (task_is_stopped_or_traced(p)) 1371 return &p->exit_code; 1372 } else { 1373 if (p->signal->flags & SIGNAL_STOP_STOPPED) 1374 return &p->signal->group_exit_code; 1375 } 1376 return NULL; 1377 } 1378 1379 /* 1380 * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold 1381 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1382 * the lock and this task is uninteresting. If we return nonzero, we have 1383 * released the lock and the system call should return. 1384 */ 1385 static int wait_task_stopped(struct wait_opts *wo, 1386 int ptrace, struct task_struct *p) 1387 { 1388 struct siginfo __user *infop; 1389 int retval, exit_code, *p_code, why; 1390 uid_t uid = 0; /* unneeded, required by compiler */ 1391 pid_t pid; 1392 1393 /* 1394 * Traditionally we see ptrace'd stopped tasks regardless of options. 1395 */ 1396 if (!ptrace && !(wo->wo_flags & WUNTRACED)) 1397 return 0; 1398 1399 exit_code = 0; 1400 spin_lock_irq(&p->sighand->siglock); 1401 1402 p_code = task_stopped_code(p, ptrace); 1403 if (unlikely(!p_code)) 1404 goto unlock_sig; 1405 1406 exit_code = *p_code; 1407 if (!exit_code) 1408 goto unlock_sig; 1409 1410 if (!unlikely(wo->wo_flags & WNOWAIT)) 1411 *p_code = 0; 1412 1413 uid = task_uid(p); 1414 unlock_sig: 1415 spin_unlock_irq(&p->sighand->siglock); 1416 if (!exit_code) 1417 return 0; 1418 1419 /* 1420 * Now we are pretty sure this task is interesting. 1421 * Make sure it doesn't get reaped out from under us while we 1422 * give up the lock and then examine it below. We don't want to 1423 * keep holding onto the tasklist_lock while we call getrusage and 1424 * possibly take page faults for user memory. 1425 */ 1426 get_task_struct(p); 1427 pid = task_pid_vnr(p); 1428 why = ptrace ? CLD_TRAPPED : CLD_STOPPED; 1429 read_unlock(&tasklist_lock); 1430 1431 if (unlikely(wo->wo_flags & WNOWAIT)) 1432 return wait_noreap_copyout(wo, p, pid, uid, why, exit_code); 1433 1434 retval = wo->wo_rusage 1435 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; 1436 if (!retval && wo->wo_stat) 1437 retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat); 1438 1439 infop = wo->wo_info; 1440 if (!retval && infop) 1441 retval = put_user(SIGCHLD, &infop->si_signo); 1442 if (!retval && infop) 1443 retval = put_user(0, &infop->si_errno); 1444 if (!retval && infop) 1445 retval = put_user((short)why, &infop->si_code); 1446 if (!retval && infop) 1447 retval = put_user(exit_code, &infop->si_status); 1448 if (!retval && infop) 1449 retval = put_user(pid, &infop->si_pid); 1450 if (!retval && infop) 1451 retval = put_user(uid, &infop->si_uid); 1452 if (!retval) 1453 retval = pid; 1454 put_task_struct(p); 1455 1456 BUG_ON(!retval); 1457 return retval; 1458 } 1459 1460 /* 1461 * Handle do_wait work for one task in a live, non-stopped state. 1462 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1463 * the lock and this task is uninteresting. If we return nonzero, we have 1464 * released the lock and the system call should return. 1465 */ 1466 static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) 1467 { 1468 int retval; 1469 pid_t pid; 1470 uid_t uid; 1471 1472 if (!unlikely(wo->wo_flags & WCONTINUED)) 1473 return 0; 1474 1475 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) 1476 return 0; 1477 1478 spin_lock_irq(&p->sighand->siglock); 1479 /* Re-check with the lock held. */ 1480 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { 1481 spin_unlock_irq(&p->sighand->siglock); 1482 return 0; 1483 } 1484 if (!unlikely(wo->wo_flags & WNOWAIT)) 1485 p->signal->flags &= ~SIGNAL_STOP_CONTINUED; 1486 uid = task_uid(p); 1487 spin_unlock_irq(&p->sighand->siglock); 1488 1489 pid = task_pid_vnr(p); 1490 get_task_struct(p); 1491 read_unlock(&tasklist_lock); 1492 1493 if (!wo->wo_info) { 1494 retval = wo->wo_rusage 1495 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; 1496 put_task_struct(p); 1497 if (!retval && wo->wo_stat) 1498 retval = put_user(0xffff, wo->wo_stat); 1499 if (!retval) 1500 retval = pid; 1501 } else { 1502 retval = wait_noreap_copyout(wo, p, pid, uid, 1503 CLD_CONTINUED, SIGCONT); 1504 BUG_ON(retval == 0); 1505 } 1506 1507 return retval; 1508 } 1509 1510 /* 1511 * Consider @p for a wait by @parent. 1512 * 1513 * -ECHILD should be in ->notask_error before the first call. 1514 * Returns nonzero for a final return, when we have unlocked tasklist_lock. 1515 * Returns zero if the search for a child should continue; 1516 * then ->notask_error is 0 if @p is an eligible child, 1517 * or another error from security_task_wait(), or still -ECHILD. 1518 */ 1519 static int wait_consider_task(struct wait_opts *wo, int ptrace, 1520 struct task_struct *p) 1521 { 1522 int ret = eligible_child(wo, p); 1523 if (!ret) 1524 return ret; 1525 1526 ret = security_task_wait(p); 1527 if (unlikely(ret < 0)) { 1528 /* 1529 * If we have not yet seen any eligible child, 1530 * then let this error code replace -ECHILD. 1531 * A permission error will give the user a clue 1532 * to look for security policy problems, rather 1533 * than for mysterious wait bugs. 1534 */ 1535 if (wo->notask_error) 1536 wo->notask_error = ret; 1537 return 0; 1538 } 1539 1540 if (likely(!ptrace) && unlikely(task_ptrace(p))) { 1541 /* 1542 * This child is hidden by ptrace. 1543 * We aren't allowed to see it now, but eventually we will. 1544 */ 1545 wo->notask_error = 0; 1546 return 0; 1547 } 1548 1549 if (p->exit_state == EXIT_DEAD) 1550 return 0; 1551 1552 /* 1553 * We don't reap group leaders with subthreads. 1554 */ 1555 if (p->exit_state == EXIT_ZOMBIE && !delay_group_leader(p)) 1556 return wait_task_zombie(wo, p); 1557 1558 /* 1559 * It's stopped or running now, so it might 1560 * later continue, exit, or stop again. 1561 */ 1562 wo->notask_error = 0; 1563 1564 if (task_stopped_code(p, ptrace)) 1565 return wait_task_stopped(wo, ptrace, p); 1566 1567 return wait_task_continued(wo, p); 1568 } 1569 1570 /* 1571 * Do the work of do_wait() for one thread in the group, @tsk. 1572 * 1573 * -ECHILD should be in ->notask_error before the first call. 1574 * Returns nonzero for a final return, when we have unlocked tasklist_lock. 1575 * Returns zero if the search for a child should continue; then 1576 * ->notask_error is 0 if there were any eligible children, 1577 * or another error from security_task_wait(), or still -ECHILD. 1578 */ 1579 static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) 1580 { 1581 struct task_struct *p; 1582 1583 list_for_each_entry(p, &tsk->children, sibling) { 1584 int ret = wait_consider_task(wo, 0, p); 1585 if (ret) 1586 return ret; 1587 } 1588 1589 return 0; 1590 } 1591 1592 static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) 1593 { 1594 struct task_struct *p; 1595 1596 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { 1597 int ret = wait_consider_task(wo, 1, p); 1598 if (ret) 1599 return ret; 1600 } 1601 1602 return 0; 1603 } 1604 1605 static int child_wait_callback(wait_queue_t *wait, unsigned mode, 1606 int sync, void *key) 1607 { 1608 struct wait_opts *wo = container_of(wait, struct wait_opts, 1609 child_wait); 1610 struct task_struct *p = key; 1611 1612 if (!eligible_pid(wo, p)) 1613 return 0; 1614 1615 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) 1616 return 0; 1617 1618 return default_wake_function(wait, mode, sync, key); 1619 } 1620 1621 void __wake_up_parent(struct task_struct *p, struct task_struct *parent) 1622 { 1623 __wake_up_sync_key(&parent->signal->wait_chldexit, 1624 TASK_INTERRUPTIBLE, 1, p); 1625 } 1626 1627 static long do_wait(struct wait_opts *wo) 1628 { 1629 struct task_struct *tsk; 1630 int retval; 1631 1632 trace_sched_process_wait(wo->wo_pid); 1633 1634 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); 1635 wo->child_wait.private = current; 1636 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); 1637 repeat: 1638 /* 1639 * If there is nothing that can match our critiera just get out. 1640 * We will clear ->notask_error to zero if we see any child that 1641 * might later match our criteria, even if we are not able to reap 1642 * it yet. 1643 */ 1644 wo->notask_error = -ECHILD; 1645 if ((wo->wo_type < PIDTYPE_MAX) && 1646 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type]))) 1647 goto notask; 1648 1649 set_current_state(TASK_INTERRUPTIBLE); 1650 read_lock(&tasklist_lock); 1651 tsk = current; 1652 do { 1653 retval = do_wait_thread(wo, tsk); 1654 if (retval) 1655 goto end; 1656 1657 retval = ptrace_do_wait(wo, tsk); 1658 if (retval) 1659 goto end; 1660 1661 if (wo->wo_flags & __WNOTHREAD) 1662 break; 1663 } while_each_thread(current, tsk); 1664 read_unlock(&tasklist_lock); 1665 1666 notask: 1667 retval = wo->notask_error; 1668 if (!retval && !(wo->wo_flags & WNOHANG)) { 1669 retval = -ERESTARTSYS; 1670 if (!signal_pending(current)) { 1671 schedule(); 1672 goto repeat; 1673 } 1674 } 1675 end: 1676 __set_current_state(TASK_RUNNING); 1677 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); 1678 return retval; 1679 } 1680 1681 SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, 1682 infop, int, options, struct rusage __user *, ru) 1683 { 1684 struct wait_opts wo; 1685 struct pid *pid = NULL; 1686 enum pid_type type; 1687 long ret; 1688 1689 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED)) 1690 return -EINVAL; 1691 if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) 1692 return -EINVAL; 1693 1694 switch (which) { 1695 case P_ALL: 1696 type = PIDTYPE_MAX; 1697 break; 1698 case P_PID: 1699 type = PIDTYPE_PID; 1700 if (upid <= 0) 1701 return -EINVAL; 1702 break; 1703 case P_PGID: 1704 type = PIDTYPE_PGID; 1705 if (upid <= 0) 1706 return -EINVAL; 1707 break; 1708 default: 1709 return -EINVAL; 1710 } 1711 1712 if (type < PIDTYPE_MAX) 1713 pid = find_get_pid(upid); 1714 1715 wo.wo_type = type; 1716 wo.wo_pid = pid; 1717 wo.wo_flags = options; 1718 wo.wo_info = infop; 1719 wo.wo_stat = NULL; 1720 wo.wo_rusage = ru; 1721 ret = do_wait(&wo); 1722 1723 if (ret > 0) { 1724 ret = 0; 1725 } else if (infop) { 1726 /* 1727 * For a WNOHANG return, clear out all the fields 1728 * we would set so the user can easily tell the 1729 * difference. 1730 */ 1731 if (!ret) 1732 ret = put_user(0, &infop->si_signo); 1733 if (!ret) 1734 ret = put_user(0, &infop->si_errno); 1735 if (!ret) 1736 ret = put_user(0, &infop->si_code); 1737 if (!ret) 1738 ret = put_user(0, &infop->si_pid); 1739 if (!ret) 1740 ret = put_user(0, &infop->si_uid); 1741 if (!ret) 1742 ret = put_user(0, &infop->si_status); 1743 } 1744 1745 put_pid(pid); 1746 1747 /* avoid REGPARM breakage on x86: */ 1748 asmlinkage_protect(5, ret, which, upid, infop, options, ru); 1749 return ret; 1750 } 1751 1752 SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, 1753 int, options, struct rusage __user *, ru) 1754 { 1755 struct wait_opts wo; 1756 struct pid *pid = NULL; 1757 enum pid_type type; 1758 long ret; 1759 1760 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| 1761 __WNOTHREAD|__WCLONE|__WALL)) 1762 return -EINVAL; 1763 1764 if (upid == -1) 1765 type = PIDTYPE_MAX; 1766 else if (upid < 0) { 1767 type = PIDTYPE_PGID; 1768 pid = find_get_pid(-upid); 1769 } else if (upid == 0) { 1770 type = PIDTYPE_PGID; 1771 pid = get_task_pid(current, PIDTYPE_PGID); 1772 } else /* upid > 0 */ { 1773 type = PIDTYPE_PID; 1774 pid = find_get_pid(upid); 1775 } 1776 1777 wo.wo_type = type; 1778 wo.wo_pid = pid; 1779 wo.wo_flags = options | WEXITED; 1780 wo.wo_info = NULL; 1781 wo.wo_stat = stat_addr; 1782 wo.wo_rusage = ru; 1783 ret = do_wait(&wo); 1784 put_pid(pid); 1785 1786 /* avoid REGPARM breakage on x86: */ 1787 asmlinkage_protect(4, ret, upid, stat_addr, options, ru); 1788 return ret; 1789 } 1790 1791 #ifdef __ARCH_WANT_SYS_WAITPID 1792 1793 /* 1794 * sys_waitpid() remains for compatibility. waitpid() should be 1795 * implemented by calling sys_wait4() from libc.a. 1796 */ 1797 SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) 1798 { 1799 return sys_wait4(pid, stat_addr, options, NULL); 1800 } 1801 1802 #endif 1803