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/sched/autogroup.h> 10 #include <linux/sched/mm.h> 11 #include <linux/sched/stat.h> 12 #include <linux/sched/task.h> 13 #include <linux/sched/task_stack.h> 14 #include <linux/sched/cputime.h> 15 #include <linux/interrupt.h> 16 #include <linux/module.h> 17 #include <linux/capability.h> 18 #include <linux/completion.h> 19 #include <linux/personality.h> 20 #include <linux/tty.h> 21 #include <linux/iocontext.h> 22 #include <linux/key.h> 23 #include <linux/cpu.h> 24 #include <linux/acct.h> 25 #include <linux/tsacct_kern.h> 26 #include <linux/file.h> 27 #include <linux/fdtable.h> 28 #include <linux/freezer.h> 29 #include <linux/binfmts.h> 30 #include <linux/nsproxy.h> 31 #include <linux/pid_namespace.h> 32 #include <linux/ptrace.h> 33 #include <linux/profile.h> 34 #include <linux/mount.h> 35 #include <linux/proc_fs.h> 36 #include <linux/kthread.h> 37 #include <linux/mempolicy.h> 38 #include <linux/taskstats_kern.h> 39 #include <linux/delayacct.h> 40 #include <linux/cgroup.h> 41 #include <linux/syscalls.h> 42 #include <linux/signal.h> 43 #include <linux/posix-timers.h> 44 #include <linux/cn_proc.h> 45 #include <linux/mutex.h> 46 #include <linux/futex.h> 47 #include <linux/pipe_fs_i.h> 48 #include <linux/audit.h> /* for audit_free() */ 49 #include <linux/resource.h> 50 #include <linux/blkdev.h> 51 #include <linux/task_io_accounting_ops.h> 52 #include <linux/tracehook.h> 53 #include <linux/fs_struct.h> 54 #include <linux/init_task.h> 55 #include <linux/perf_event.h> 56 #include <trace/events/sched.h> 57 #include <linux/hw_breakpoint.h> 58 #include <linux/oom.h> 59 #include <linux/writeback.h> 60 #include <linux/shm.h> 61 #include <linux/kcov.h> 62 #include <linux/random.h> 63 #include <linux/rcuwait.h> 64 #include <linux/compat.h> 65 66 #include <linux/uaccess.h> 67 #include <asm/unistd.h> 68 #include <asm/pgtable.h> 69 #include <asm/mmu_context.h> 70 71 static void __unhash_process(struct task_struct *p, bool group_dead) 72 { 73 nr_threads--; 74 detach_pid(p, PIDTYPE_PID); 75 if (group_dead) { 76 detach_pid(p, PIDTYPE_PGID); 77 detach_pid(p, PIDTYPE_SID); 78 79 list_del_rcu(&p->tasks); 80 list_del_init(&p->sibling); 81 __this_cpu_dec(process_counts); 82 } 83 list_del_rcu(&p->thread_group); 84 list_del_rcu(&p->thread_node); 85 } 86 87 /* 88 * This function expects the tasklist_lock write-locked. 89 */ 90 static void __exit_signal(struct task_struct *tsk) 91 { 92 struct signal_struct *sig = tsk->signal; 93 bool group_dead = thread_group_leader(tsk); 94 struct sighand_struct *sighand; 95 struct tty_struct *uninitialized_var(tty); 96 u64 utime, stime; 97 98 sighand = rcu_dereference_check(tsk->sighand, 99 lockdep_tasklist_lock_is_held()); 100 spin_lock(&sighand->siglock); 101 102 #ifdef CONFIG_POSIX_TIMERS 103 posix_cpu_timers_exit(tsk); 104 if (group_dead) { 105 posix_cpu_timers_exit_group(tsk); 106 } else { 107 /* 108 * This can only happen if the caller is de_thread(). 109 * FIXME: this is the temporary hack, we should teach 110 * posix-cpu-timers to handle this case correctly. 111 */ 112 if (unlikely(has_group_leader_pid(tsk))) 113 posix_cpu_timers_exit_group(tsk); 114 } 115 #endif 116 117 if (group_dead) { 118 tty = sig->tty; 119 sig->tty = NULL; 120 } else { 121 /* 122 * If there is any task waiting for the group exit 123 * then notify it: 124 */ 125 if (sig->notify_count > 0 && !--sig->notify_count) 126 wake_up_process(sig->group_exit_task); 127 128 if (tsk == sig->curr_target) 129 sig->curr_target = next_thread(tsk); 130 } 131 132 add_device_randomness((const void*) &tsk->se.sum_exec_runtime, 133 sizeof(unsigned long long)); 134 135 /* 136 * Accumulate here the counters for all threads as they die. We could 137 * skip the group leader because it is the last user of signal_struct, 138 * but we want to avoid the race with thread_group_cputime() which can 139 * see the empty ->thread_head list. 140 */ 141 task_cputime(tsk, &utime, &stime); 142 write_seqlock(&sig->stats_lock); 143 sig->utime += utime; 144 sig->stime += stime; 145 sig->gtime += task_gtime(tsk); 146 sig->min_flt += tsk->min_flt; 147 sig->maj_flt += tsk->maj_flt; 148 sig->nvcsw += tsk->nvcsw; 149 sig->nivcsw += tsk->nivcsw; 150 sig->inblock += task_io_get_inblock(tsk); 151 sig->oublock += task_io_get_oublock(tsk); 152 task_io_accounting_add(&sig->ioac, &tsk->ioac); 153 sig->sum_sched_runtime += tsk->se.sum_exec_runtime; 154 sig->nr_threads--; 155 __unhash_process(tsk, group_dead); 156 write_sequnlock(&sig->stats_lock); 157 158 /* 159 * Do this under ->siglock, we can race with another thread 160 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. 161 */ 162 flush_sigqueue(&tsk->pending); 163 tsk->sighand = NULL; 164 spin_unlock(&sighand->siglock); 165 166 __cleanup_sighand(sighand); 167 clear_tsk_thread_flag(tsk, TIF_SIGPENDING); 168 if (group_dead) { 169 flush_sigqueue(&sig->shared_pending); 170 tty_kref_put(tty); 171 } 172 } 173 174 static void delayed_put_task_struct(struct rcu_head *rhp) 175 { 176 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); 177 178 perf_event_delayed_put(tsk); 179 trace_sched_process_free(tsk); 180 put_task_struct(tsk); 181 } 182 183 184 void release_task(struct task_struct *p) 185 { 186 struct task_struct *leader; 187 int zap_leader; 188 repeat: 189 /* don't need to get the RCU readlock here - the process is dead and 190 * can't be modifying its own credentials. But shut RCU-lockdep up */ 191 rcu_read_lock(); 192 atomic_dec(&__task_cred(p)->user->processes); 193 rcu_read_unlock(); 194 195 proc_flush_task(p); 196 197 write_lock_irq(&tasklist_lock); 198 ptrace_release_task(p); 199 __exit_signal(p); 200 201 /* 202 * If we are the last non-leader member of the thread 203 * group, and the leader is zombie, then notify the 204 * group leader's parent process. (if it wants notification.) 205 */ 206 zap_leader = 0; 207 leader = p->group_leader; 208 if (leader != p && thread_group_empty(leader) 209 && leader->exit_state == EXIT_ZOMBIE) { 210 /* 211 * If we were the last child thread and the leader has 212 * exited already, and the leader's parent ignores SIGCHLD, 213 * then we are the one who should release the leader. 214 */ 215 zap_leader = do_notify_parent(leader, leader->exit_signal); 216 if (zap_leader) 217 leader->exit_state = EXIT_DEAD; 218 } 219 220 write_unlock_irq(&tasklist_lock); 221 release_thread(p); 222 call_rcu(&p->rcu, delayed_put_task_struct); 223 224 p = leader; 225 if (unlikely(zap_leader)) 226 goto repeat; 227 } 228 229 /* 230 * Note that if this function returns a valid task_struct pointer (!NULL) 231 * task->usage must remain >0 for the duration of the RCU critical section. 232 */ 233 struct task_struct *task_rcu_dereference(struct task_struct **ptask) 234 { 235 struct sighand_struct *sighand; 236 struct task_struct *task; 237 238 /* 239 * We need to verify that release_task() was not called and thus 240 * delayed_put_task_struct() can't run and drop the last reference 241 * before rcu_read_unlock(). We check task->sighand != NULL, 242 * but we can read the already freed and reused memory. 243 */ 244 retry: 245 task = rcu_dereference(*ptask); 246 if (!task) 247 return NULL; 248 249 probe_kernel_address(&task->sighand, sighand); 250 251 /* 252 * Pairs with atomic_dec_and_test() in put_task_struct(). If this task 253 * was already freed we can not miss the preceding update of this 254 * pointer. 255 */ 256 smp_rmb(); 257 if (unlikely(task != READ_ONCE(*ptask))) 258 goto retry; 259 260 /* 261 * We've re-checked that "task == *ptask", now we have two different 262 * cases: 263 * 264 * 1. This is actually the same task/task_struct. In this case 265 * sighand != NULL tells us it is still alive. 266 * 267 * 2. This is another task which got the same memory for task_struct. 268 * We can't know this of course, and we can not trust 269 * sighand != NULL. 270 * 271 * In this case we actually return a random value, but this is 272 * correct. 273 * 274 * If we return NULL - we can pretend that we actually noticed that 275 * *ptask was updated when the previous task has exited. Or pretend 276 * that probe_slab_address(&sighand) reads NULL. 277 * 278 * If we return the new task (because sighand is not NULL for any 279 * reason) - this is fine too. This (new) task can't go away before 280 * another gp pass. 281 * 282 * And note: We could even eliminate the false positive if re-read 283 * task->sighand once again to avoid the falsely NULL. But this case 284 * is very unlikely so we don't care. 285 */ 286 if (!sighand) 287 return NULL; 288 289 return task; 290 } 291 292 void rcuwait_wake_up(struct rcuwait *w) 293 { 294 struct task_struct *task; 295 296 rcu_read_lock(); 297 298 /* 299 * Order condition vs @task, such that everything prior to the load 300 * of @task is visible. This is the condition as to why the user called 301 * rcuwait_trywake() in the first place. Pairs with set_current_state() 302 * barrier (A) in rcuwait_wait_event(). 303 * 304 * WAIT WAKE 305 * [S] tsk = current [S] cond = true 306 * MB (A) MB (B) 307 * [L] cond [L] tsk 308 */ 309 smp_rmb(); /* (B) */ 310 311 /* 312 * Avoid using task_rcu_dereference() magic as long as we are careful, 313 * see comment in rcuwait_wait_event() regarding ->exit_state. 314 */ 315 task = rcu_dereference(w->task); 316 if (task) 317 wake_up_process(task); 318 rcu_read_unlock(); 319 } 320 321 /* 322 * Determine if a process group is "orphaned", according to the POSIX 323 * definition in 2.2.2.52. Orphaned process groups are not to be affected 324 * by terminal-generated stop signals. Newly orphaned process groups are 325 * to receive a SIGHUP and a SIGCONT. 326 * 327 * "I ask you, have you ever known what it is to be an orphan?" 328 */ 329 static int will_become_orphaned_pgrp(struct pid *pgrp, 330 struct task_struct *ignored_task) 331 { 332 struct task_struct *p; 333 334 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 335 if ((p == ignored_task) || 336 (p->exit_state && thread_group_empty(p)) || 337 is_global_init(p->real_parent)) 338 continue; 339 340 if (task_pgrp(p->real_parent) != pgrp && 341 task_session(p->real_parent) == task_session(p)) 342 return 0; 343 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 344 345 return 1; 346 } 347 348 int is_current_pgrp_orphaned(void) 349 { 350 int retval; 351 352 read_lock(&tasklist_lock); 353 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); 354 read_unlock(&tasklist_lock); 355 356 return retval; 357 } 358 359 static bool has_stopped_jobs(struct pid *pgrp) 360 { 361 struct task_struct *p; 362 363 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 364 if (p->signal->flags & SIGNAL_STOP_STOPPED) 365 return true; 366 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 367 368 return false; 369 } 370 371 /* 372 * Check to see if any process groups have become orphaned as 373 * a result of our exiting, and if they have any stopped jobs, 374 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 375 */ 376 static void 377 kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) 378 { 379 struct pid *pgrp = task_pgrp(tsk); 380 struct task_struct *ignored_task = tsk; 381 382 if (!parent) 383 /* exit: our father is in a different pgrp than 384 * we are and we were the only connection outside. 385 */ 386 parent = tsk->real_parent; 387 else 388 /* reparent: our child is in a different pgrp than 389 * we are, and it was the only connection outside. 390 */ 391 ignored_task = NULL; 392 393 if (task_pgrp(parent) != pgrp && 394 task_session(parent) == task_session(tsk) && 395 will_become_orphaned_pgrp(pgrp, ignored_task) && 396 has_stopped_jobs(pgrp)) { 397 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); 398 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); 399 } 400 } 401 402 #ifdef CONFIG_MEMCG 403 /* 404 * A task is exiting. If it owned this mm, find a new owner for the mm. 405 */ 406 void mm_update_next_owner(struct mm_struct *mm) 407 { 408 struct task_struct *c, *g, *p = current; 409 410 retry: 411 /* 412 * If the exiting or execing task is not the owner, it's 413 * someone else's problem. 414 */ 415 if (mm->owner != p) 416 return; 417 /* 418 * The current owner is exiting/execing and there are no other 419 * candidates. Do not leave the mm pointing to a possibly 420 * freed task structure. 421 */ 422 if (atomic_read(&mm->mm_users) <= 1) { 423 mm->owner = NULL; 424 return; 425 } 426 427 read_lock(&tasklist_lock); 428 /* 429 * Search in the children 430 */ 431 list_for_each_entry(c, &p->children, sibling) { 432 if (c->mm == mm) 433 goto assign_new_owner; 434 } 435 436 /* 437 * Search in the siblings 438 */ 439 list_for_each_entry(c, &p->real_parent->children, sibling) { 440 if (c->mm == mm) 441 goto assign_new_owner; 442 } 443 444 /* 445 * Search through everything else, we should not get here often. 446 */ 447 for_each_process(g) { 448 if (g->flags & PF_KTHREAD) 449 continue; 450 for_each_thread(g, c) { 451 if (c->mm == mm) 452 goto assign_new_owner; 453 if (c->mm) 454 break; 455 } 456 } 457 read_unlock(&tasklist_lock); 458 /* 459 * We found no owner yet mm_users > 1: this implies that we are 460 * most likely racing with swapoff (try_to_unuse()) or /proc or 461 * ptrace or page migration (get_task_mm()). Mark owner as NULL. 462 */ 463 mm->owner = NULL; 464 return; 465 466 assign_new_owner: 467 BUG_ON(c == p); 468 get_task_struct(c); 469 /* 470 * The task_lock protects c->mm from changing. 471 * We always want mm->owner->mm == mm 472 */ 473 task_lock(c); 474 /* 475 * Delay read_unlock() till we have the task_lock() 476 * to ensure that c does not slip away underneath us 477 */ 478 read_unlock(&tasklist_lock); 479 if (c->mm != mm) { 480 task_unlock(c); 481 put_task_struct(c); 482 goto retry; 483 } 484 mm->owner = c; 485 task_unlock(c); 486 put_task_struct(c); 487 } 488 #endif /* CONFIG_MEMCG */ 489 490 /* 491 * Turn us into a lazy TLB process if we 492 * aren't already.. 493 */ 494 static void exit_mm(void) 495 { 496 struct mm_struct *mm = current->mm; 497 struct core_state *core_state; 498 499 mm_release(current, mm); 500 if (!mm) 501 return; 502 sync_mm_rss(mm); 503 /* 504 * Serialize with any possible pending coredump. 505 * We must hold mmap_sem around checking core_state 506 * and clearing tsk->mm. The core-inducing thread 507 * will increment ->nr_threads for each thread in the 508 * group with ->mm != NULL. 509 */ 510 down_read(&mm->mmap_sem); 511 core_state = mm->core_state; 512 if (core_state) { 513 struct core_thread self; 514 515 up_read(&mm->mmap_sem); 516 517 self.task = current; 518 self.next = xchg(&core_state->dumper.next, &self); 519 /* 520 * Implies mb(), the result of xchg() must be visible 521 * to core_state->dumper. 522 */ 523 if (atomic_dec_and_test(&core_state->nr_threads)) 524 complete(&core_state->startup); 525 526 for (;;) { 527 set_current_state(TASK_UNINTERRUPTIBLE); 528 if (!self.task) /* see coredump_finish() */ 529 break; 530 freezable_schedule(); 531 } 532 __set_current_state(TASK_RUNNING); 533 down_read(&mm->mmap_sem); 534 } 535 mmgrab(mm); 536 BUG_ON(mm != current->active_mm); 537 /* more a memory barrier than a real lock */ 538 task_lock(current); 539 current->mm = NULL; 540 up_read(&mm->mmap_sem); 541 enter_lazy_tlb(mm, current); 542 task_unlock(current); 543 mm_update_next_owner(mm); 544 mmput(mm); 545 if (test_thread_flag(TIF_MEMDIE)) 546 exit_oom_victim(); 547 } 548 549 static struct task_struct *find_alive_thread(struct task_struct *p) 550 { 551 struct task_struct *t; 552 553 for_each_thread(p, t) { 554 if (!(t->flags & PF_EXITING)) 555 return t; 556 } 557 return NULL; 558 } 559 560 static struct task_struct *find_child_reaper(struct task_struct *father) 561 __releases(&tasklist_lock) 562 __acquires(&tasklist_lock) 563 { 564 struct pid_namespace *pid_ns = task_active_pid_ns(father); 565 struct task_struct *reaper = pid_ns->child_reaper; 566 567 if (likely(reaper != father)) 568 return reaper; 569 570 reaper = find_alive_thread(father); 571 if (reaper) { 572 pid_ns->child_reaper = reaper; 573 return reaper; 574 } 575 576 write_unlock_irq(&tasklist_lock); 577 if (unlikely(pid_ns == &init_pid_ns)) { 578 panic("Attempted to kill init! exitcode=0x%08x\n", 579 father->signal->group_exit_code ?: father->exit_code); 580 } 581 zap_pid_ns_processes(pid_ns); 582 write_lock_irq(&tasklist_lock); 583 584 return father; 585 } 586 587 /* 588 * When we die, we re-parent all our children, and try to: 589 * 1. give them to another thread in our thread group, if such a member exists 590 * 2. give it to the first ancestor process which prctl'd itself as a 591 * child_subreaper for its children (like a service manager) 592 * 3. give it to the init process (PID 1) in our pid namespace 593 */ 594 static struct task_struct *find_new_reaper(struct task_struct *father, 595 struct task_struct *child_reaper) 596 { 597 struct task_struct *thread, *reaper; 598 599 thread = find_alive_thread(father); 600 if (thread) 601 return thread; 602 603 if (father->signal->has_child_subreaper) { 604 unsigned int ns_level = task_pid(father)->level; 605 /* 606 * Find the first ->is_child_subreaper ancestor in our pid_ns. 607 * We can't check reaper != child_reaper to ensure we do not 608 * cross the namespaces, the exiting parent could be injected 609 * by setns() + fork(). 610 * We check pid->level, this is slightly more efficient than 611 * task_active_pid_ns(reaper) != task_active_pid_ns(father). 612 */ 613 for (reaper = father->real_parent; 614 task_pid(reaper)->level == ns_level; 615 reaper = reaper->real_parent) { 616 if (reaper == &init_task) 617 break; 618 if (!reaper->signal->is_child_subreaper) 619 continue; 620 thread = find_alive_thread(reaper); 621 if (thread) 622 return thread; 623 } 624 } 625 626 return child_reaper; 627 } 628 629 /* 630 * Any that need to be release_task'd are put on the @dead list. 631 */ 632 static void reparent_leader(struct task_struct *father, struct task_struct *p, 633 struct list_head *dead) 634 { 635 if (unlikely(p->exit_state == EXIT_DEAD)) 636 return; 637 638 /* We don't want people slaying init. */ 639 p->exit_signal = SIGCHLD; 640 641 /* If it has exited notify the new parent about this child's death. */ 642 if (!p->ptrace && 643 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { 644 if (do_notify_parent(p, p->exit_signal)) { 645 p->exit_state = EXIT_DEAD; 646 list_add(&p->ptrace_entry, dead); 647 } 648 } 649 650 kill_orphaned_pgrp(p, father); 651 } 652 653 /* 654 * This does two things: 655 * 656 * A. Make init inherit all the child processes 657 * B. Check to see if any process groups have become orphaned 658 * as a result of our exiting, and if they have any stopped 659 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 660 */ 661 static void forget_original_parent(struct task_struct *father, 662 struct list_head *dead) 663 { 664 struct task_struct *p, *t, *reaper; 665 666 if (unlikely(!list_empty(&father->ptraced))) 667 exit_ptrace(father, dead); 668 669 /* Can drop and reacquire tasklist_lock */ 670 reaper = find_child_reaper(father); 671 if (list_empty(&father->children)) 672 return; 673 674 reaper = find_new_reaper(father, reaper); 675 list_for_each_entry(p, &father->children, sibling) { 676 for_each_thread(p, t) { 677 t->real_parent = reaper; 678 BUG_ON((!t->ptrace) != (t->parent == father)); 679 if (likely(!t->ptrace)) 680 t->parent = t->real_parent; 681 if (t->pdeath_signal) 682 group_send_sig_info(t->pdeath_signal, 683 SEND_SIG_NOINFO, t); 684 } 685 /* 686 * If this is a threaded reparent there is no need to 687 * notify anyone anything has happened. 688 */ 689 if (!same_thread_group(reaper, father)) 690 reparent_leader(father, p, dead); 691 } 692 list_splice_tail_init(&father->children, &reaper->children); 693 } 694 695 /* 696 * Send signals to all our closest relatives so that they know 697 * to properly mourn us.. 698 */ 699 static void exit_notify(struct task_struct *tsk, int group_dead) 700 { 701 bool autoreap; 702 struct task_struct *p, *n; 703 LIST_HEAD(dead); 704 705 write_lock_irq(&tasklist_lock); 706 forget_original_parent(tsk, &dead); 707 708 if (group_dead) 709 kill_orphaned_pgrp(tsk->group_leader, NULL); 710 711 if (unlikely(tsk->ptrace)) { 712 int sig = thread_group_leader(tsk) && 713 thread_group_empty(tsk) && 714 !ptrace_reparented(tsk) ? 715 tsk->exit_signal : SIGCHLD; 716 autoreap = do_notify_parent(tsk, sig); 717 } else if (thread_group_leader(tsk)) { 718 autoreap = thread_group_empty(tsk) && 719 do_notify_parent(tsk, tsk->exit_signal); 720 } else { 721 autoreap = true; 722 } 723 724 tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE; 725 if (tsk->exit_state == EXIT_DEAD) 726 list_add(&tsk->ptrace_entry, &dead); 727 728 /* mt-exec, de_thread() is waiting for group leader */ 729 if (unlikely(tsk->signal->notify_count < 0)) 730 wake_up_process(tsk->signal->group_exit_task); 731 write_unlock_irq(&tasklist_lock); 732 733 list_for_each_entry_safe(p, n, &dead, ptrace_entry) { 734 list_del_init(&p->ptrace_entry); 735 release_task(p); 736 } 737 } 738 739 #ifdef CONFIG_DEBUG_STACK_USAGE 740 static void check_stack_usage(void) 741 { 742 static DEFINE_SPINLOCK(low_water_lock); 743 static int lowest_to_date = THREAD_SIZE; 744 unsigned long free; 745 746 free = stack_not_used(current); 747 748 if (free >= lowest_to_date) 749 return; 750 751 spin_lock(&low_water_lock); 752 if (free < lowest_to_date) { 753 pr_info("%s (%d) used greatest stack depth: %lu bytes left\n", 754 current->comm, task_pid_nr(current), free); 755 lowest_to_date = free; 756 } 757 spin_unlock(&low_water_lock); 758 } 759 #else 760 static inline void check_stack_usage(void) {} 761 #endif 762 763 void __noreturn do_exit(long code) 764 { 765 struct task_struct *tsk = current; 766 int group_dead; 767 768 profile_task_exit(tsk); 769 kcov_task_exit(tsk); 770 771 WARN_ON(blk_needs_flush_plug(tsk)); 772 773 if (unlikely(in_interrupt())) 774 panic("Aiee, killing interrupt handler!"); 775 if (unlikely(!tsk->pid)) 776 panic("Attempted to kill the idle task!"); 777 778 /* 779 * If do_exit is called because this processes oopsed, it's possible 780 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before 781 * continuing. Amongst other possible reasons, this is to prevent 782 * mm_release()->clear_child_tid() from writing to a user-controlled 783 * kernel address. 784 */ 785 set_fs(USER_DS); 786 787 ptrace_event(PTRACE_EVENT_EXIT, code); 788 789 validate_creds_for_do_exit(tsk); 790 791 /* 792 * We're taking recursive faults here in do_exit. Safest is to just 793 * leave this task alone and wait for reboot. 794 */ 795 if (unlikely(tsk->flags & PF_EXITING)) { 796 pr_alert("Fixing recursive fault but reboot is needed!\n"); 797 /* 798 * We can do this unlocked here. The futex code uses 799 * this flag just to verify whether the pi state 800 * cleanup has been done or not. In the worst case it 801 * loops once more. We pretend that the cleanup was 802 * done as there is no way to return. Either the 803 * OWNER_DIED bit is set by now or we push the blocked 804 * task into the wait for ever nirwana as well. 805 */ 806 tsk->flags |= PF_EXITPIDONE; 807 set_current_state(TASK_UNINTERRUPTIBLE); 808 schedule(); 809 } 810 811 exit_signals(tsk); /* sets PF_EXITING */ 812 /* 813 * Ensure that all new tsk->pi_lock acquisitions must observe 814 * PF_EXITING. Serializes against futex.c:attach_to_pi_owner(). 815 */ 816 smp_mb(); 817 /* 818 * Ensure that we must observe the pi_state in exit_mm() -> 819 * mm_release() -> exit_pi_state_list(). 820 */ 821 raw_spin_lock_irq(&tsk->pi_lock); 822 raw_spin_unlock_irq(&tsk->pi_lock); 823 824 if (unlikely(in_atomic())) { 825 pr_info("note: %s[%d] exited with preempt_count %d\n", 826 current->comm, task_pid_nr(current), 827 preempt_count()); 828 preempt_count_set(PREEMPT_ENABLED); 829 } 830 831 /* sync mm's RSS info before statistics gathering */ 832 if (tsk->mm) 833 sync_mm_rss(tsk->mm); 834 acct_update_integrals(tsk); 835 group_dead = atomic_dec_and_test(&tsk->signal->live); 836 if (group_dead) { 837 #ifdef CONFIG_POSIX_TIMERS 838 hrtimer_cancel(&tsk->signal->real_timer); 839 exit_itimers(tsk->signal); 840 #endif 841 if (tsk->mm) 842 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); 843 } 844 acct_collect(code, group_dead); 845 if (group_dead) 846 tty_audit_exit(); 847 audit_free(tsk); 848 849 tsk->exit_code = code; 850 taskstats_exit(tsk, group_dead); 851 852 exit_mm(); 853 854 if (group_dead) 855 acct_process(); 856 trace_sched_process_exit(tsk); 857 858 exit_sem(tsk); 859 exit_shm(tsk); 860 exit_files(tsk); 861 exit_fs(tsk); 862 if (group_dead) 863 disassociate_ctty(1); 864 exit_task_namespaces(tsk); 865 exit_task_work(tsk); 866 exit_thread(tsk); 867 868 /* 869 * Flush inherited counters to the parent - before the parent 870 * gets woken up by child-exit notifications. 871 * 872 * because of cgroup mode, must be called before cgroup_exit() 873 */ 874 perf_event_exit_task(tsk); 875 876 sched_autogroup_exit_task(tsk); 877 cgroup_exit(tsk); 878 879 /* 880 * FIXME: do that only when needed, using sched_exit tracepoint 881 */ 882 flush_ptrace_hw_breakpoint(tsk); 883 884 exit_tasks_rcu_start(); 885 exit_notify(tsk, group_dead); 886 proc_exit_connector(tsk); 887 mpol_put_task_policy(tsk); 888 #ifdef CONFIG_FUTEX 889 if (unlikely(current->pi_state_cache)) 890 kfree(current->pi_state_cache); 891 #endif 892 /* 893 * Make sure we are holding no locks: 894 */ 895 debug_check_no_locks_held(); 896 /* 897 * We can do this unlocked here. The futex code uses this flag 898 * just to verify whether the pi state cleanup has been done 899 * or not. In the worst case it loops once more. 900 */ 901 tsk->flags |= PF_EXITPIDONE; 902 903 if (tsk->io_context) 904 exit_io_context(tsk); 905 906 if (tsk->splice_pipe) 907 free_pipe_info(tsk->splice_pipe); 908 909 if (tsk->task_frag.page) 910 put_page(tsk->task_frag.page); 911 912 validate_creds_for_do_exit(tsk); 913 914 check_stack_usage(); 915 preempt_disable(); 916 if (tsk->nr_dirtied) 917 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); 918 exit_rcu(); 919 exit_tasks_rcu_finish(); 920 921 lockdep_free_task(tsk); 922 do_task_dead(); 923 } 924 EXPORT_SYMBOL_GPL(do_exit); 925 926 void complete_and_exit(struct completion *comp, long code) 927 { 928 if (comp) 929 complete(comp); 930 931 do_exit(code); 932 } 933 EXPORT_SYMBOL(complete_and_exit); 934 935 SYSCALL_DEFINE1(exit, int, error_code) 936 { 937 do_exit((error_code&0xff)<<8); 938 } 939 940 /* 941 * Take down every thread in the group. This is called by fatal signals 942 * as well as by sys_exit_group (below). 943 */ 944 void 945 do_group_exit(int exit_code) 946 { 947 struct signal_struct *sig = current->signal; 948 949 BUG_ON(exit_code & 0x80); /* core dumps don't get here */ 950 951 if (signal_group_exit(sig)) 952 exit_code = sig->group_exit_code; 953 else if (!thread_group_empty(current)) { 954 struct sighand_struct *const sighand = current->sighand; 955 956 spin_lock_irq(&sighand->siglock); 957 if (signal_group_exit(sig)) 958 /* Another thread got here before we took the lock. */ 959 exit_code = sig->group_exit_code; 960 else { 961 sig->group_exit_code = exit_code; 962 sig->flags = SIGNAL_GROUP_EXIT; 963 zap_other_threads(current); 964 } 965 spin_unlock_irq(&sighand->siglock); 966 } 967 968 do_exit(exit_code); 969 /* NOTREACHED */ 970 } 971 972 /* 973 * this kills every thread in the thread group. Note that any externally 974 * wait4()-ing process will get the correct exit code - even if this 975 * thread is not the thread group leader. 976 */ 977 SYSCALL_DEFINE1(exit_group, int, error_code) 978 { 979 do_group_exit((error_code & 0xff) << 8); 980 /* NOTREACHED */ 981 return 0; 982 } 983 984 struct waitid_info { 985 pid_t pid; 986 uid_t uid; 987 int status; 988 int cause; 989 }; 990 991 struct wait_opts { 992 enum pid_type wo_type; 993 int wo_flags; 994 struct pid *wo_pid; 995 996 struct waitid_info *wo_info; 997 int wo_stat; 998 struct rusage *wo_rusage; 999 1000 wait_queue_entry_t child_wait; 1001 int notask_error; 1002 }; 1003 1004 static inline 1005 struct pid *task_pid_type(struct task_struct *task, enum pid_type type) 1006 { 1007 if (type != PIDTYPE_PID) 1008 task = task->group_leader; 1009 return task->pids[type].pid; 1010 } 1011 1012 static int eligible_pid(struct wait_opts *wo, struct task_struct *p) 1013 { 1014 return wo->wo_type == PIDTYPE_MAX || 1015 task_pid_type(p, wo->wo_type) == wo->wo_pid; 1016 } 1017 1018 static int 1019 eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p) 1020 { 1021 if (!eligible_pid(wo, p)) 1022 return 0; 1023 1024 /* 1025 * Wait for all children (clone and not) if __WALL is set or 1026 * if it is traced by us. 1027 */ 1028 if (ptrace || (wo->wo_flags & __WALL)) 1029 return 1; 1030 1031 /* 1032 * Otherwise, wait for clone children *only* if __WCLONE is set; 1033 * otherwise, wait for non-clone children *only*. 1034 * 1035 * Note: a "clone" child here is one that reports to its parent 1036 * using a signal other than SIGCHLD, or a non-leader thread which 1037 * we can only see if it is traced by us. 1038 */ 1039 if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) 1040 return 0; 1041 1042 return 1; 1043 } 1044 1045 /* 1046 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold 1047 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1048 * the lock and this task is uninteresting. If we return nonzero, we have 1049 * released the lock and the system call should return. 1050 */ 1051 static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) 1052 { 1053 int state, status; 1054 pid_t pid = task_pid_vnr(p); 1055 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1056 struct waitid_info *infop; 1057 1058 if (!likely(wo->wo_flags & WEXITED)) 1059 return 0; 1060 1061 if (unlikely(wo->wo_flags & WNOWAIT)) { 1062 status = p->exit_code; 1063 get_task_struct(p); 1064 read_unlock(&tasklist_lock); 1065 sched_annotate_sleep(); 1066 if (wo->wo_rusage) 1067 getrusage(p, RUSAGE_BOTH, wo->wo_rusage); 1068 put_task_struct(p); 1069 goto out_info; 1070 } 1071 /* 1072 * Move the task's state to DEAD/TRACE, only one thread can do this. 1073 */ 1074 state = (ptrace_reparented(p) && thread_group_leader(p)) ? 1075 EXIT_TRACE : EXIT_DEAD; 1076 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) 1077 return 0; 1078 /* 1079 * We own this thread, nobody else can reap it. 1080 */ 1081 read_unlock(&tasklist_lock); 1082 sched_annotate_sleep(); 1083 1084 /* 1085 * Check thread_group_leader() to exclude the traced sub-threads. 1086 */ 1087 if (state == EXIT_DEAD && thread_group_leader(p)) { 1088 struct signal_struct *sig = p->signal; 1089 struct signal_struct *psig = current->signal; 1090 unsigned long maxrss; 1091 u64 tgutime, tgstime; 1092 1093 /* 1094 * The resource counters for the group leader are in its 1095 * own task_struct. Those for dead threads in the group 1096 * are in its signal_struct, as are those for the child 1097 * processes it has previously reaped. All these 1098 * accumulate in the parent's signal_struct c* fields. 1099 * 1100 * We don't bother to take a lock here to protect these 1101 * p->signal fields because the whole thread group is dead 1102 * and nobody can change them. 1103 * 1104 * psig->stats_lock also protects us from our sub-theads 1105 * which can reap other children at the same time. Until 1106 * we change k_getrusage()-like users to rely on this lock 1107 * we have to take ->siglock as well. 1108 * 1109 * We use thread_group_cputime_adjusted() to get times for 1110 * the thread group, which consolidates times for all threads 1111 * in the group including the group leader. 1112 */ 1113 thread_group_cputime_adjusted(p, &tgutime, &tgstime); 1114 spin_lock_irq(¤t->sighand->siglock); 1115 write_seqlock(&psig->stats_lock); 1116 psig->cutime += tgutime + sig->cutime; 1117 psig->cstime += tgstime + sig->cstime; 1118 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime; 1119 psig->cmin_flt += 1120 p->min_flt + sig->min_flt + sig->cmin_flt; 1121 psig->cmaj_flt += 1122 p->maj_flt + sig->maj_flt + sig->cmaj_flt; 1123 psig->cnvcsw += 1124 p->nvcsw + sig->nvcsw + sig->cnvcsw; 1125 psig->cnivcsw += 1126 p->nivcsw + sig->nivcsw + sig->cnivcsw; 1127 psig->cinblock += 1128 task_io_get_inblock(p) + 1129 sig->inblock + sig->cinblock; 1130 psig->coublock += 1131 task_io_get_oublock(p) + 1132 sig->oublock + sig->coublock; 1133 maxrss = max(sig->maxrss, sig->cmaxrss); 1134 if (psig->cmaxrss < maxrss) 1135 psig->cmaxrss = maxrss; 1136 task_io_accounting_add(&psig->ioac, &p->ioac); 1137 task_io_accounting_add(&psig->ioac, &sig->ioac); 1138 write_sequnlock(&psig->stats_lock); 1139 spin_unlock_irq(¤t->sighand->siglock); 1140 } 1141 1142 if (wo->wo_rusage) 1143 getrusage(p, RUSAGE_BOTH, wo->wo_rusage); 1144 status = (p->signal->flags & SIGNAL_GROUP_EXIT) 1145 ? p->signal->group_exit_code : p->exit_code; 1146 wo->wo_stat = status; 1147 1148 if (state == EXIT_TRACE) { 1149 write_lock_irq(&tasklist_lock); 1150 /* We dropped tasklist, ptracer could die and untrace */ 1151 ptrace_unlink(p); 1152 1153 /* If parent wants a zombie, don't release it now */ 1154 state = EXIT_ZOMBIE; 1155 if (do_notify_parent(p, p->exit_signal)) 1156 state = EXIT_DEAD; 1157 p->exit_state = state; 1158 write_unlock_irq(&tasklist_lock); 1159 } 1160 if (state == EXIT_DEAD) 1161 release_task(p); 1162 1163 out_info: 1164 infop = wo->wo_info; 1165 if (infop) { 1166 if ((status & 0x7f) == 0) { 1167 infop->cause = CLD_EXITED; 1168 infop->status = status >> 8; 1169 } else { 1170 infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; 1171 infop->status = status & 0x7f; 1172 } 1173 infop->pid = pid; 1174 infop->uid = uid; 1175 } 1176 1177 return pid; 1178 } 1179 1180 static int *task_stopped_code(struct task_struct *p, bool ptrace) 1181 { 1182 if (ptrace) { 1183 if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING)) 1184 return &p->exit_code; 1185 } else { 1186 if (p->signal->flags & SIGNAL_STOP_STOPPED) 1187 return &p->signal->group_exit_code; 1188 } 1189 return NULL; 1190 } 1191 1192 /** 1193 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED 1194 * @wo: wait options 1195 * @ptrace: is the wait for ptrace 1196 * @p: task to wait for 1197 * 1198 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED. 1199 * 1200 * CONTEXT: 1201 * read_lock(&tasklist_lock), which is released if return value is 1202 * non-zero. Also, grabs and releases @p->sighand->siglock. 1203 * 1204 * RETURNS: 1205 * 0 if wait condition didn't exist and search for other wait conditions 1206 * should continue. Non-zero return, -errno on failure and @p's pid on 1207 * success, implies that tasklist_lock is released and wait condition 1208 * search should terminate. 1209 */ 1210 static int wait_task_stopped(struct wait_opts *wo, 1211 int ptrace, struct task_struct *p) 1212 { 1213 struct waitid_info *infop; 1214 int exit_code, *p_code, why; 1215 uid_t uid = 0; /* unneeded, required by compiler */ 1216 pid_t pid; 1217 1218 /* 1219 * Traditionally we see ptrace'd stopped tasks regardless of options. 1220 */ 1221 if (!ptrace && !(wo->wo_flags & WUNTRACED)) 1222 return 0; 1223 1224 if (!task_stopped_code(p, ptrace)) 1225 return 0; 1226 1227 exit_code = 0; 1228 spin_lock_irq(&p->sighand->siglock); 1229 1230 p_code = task_stopped_code(p, ptrace); 1231 if (unlikely(!p_code)) 1232 goto unlock_sig; 1233 1234 exit_code = *p_code; 1235 if (!exit_code) 1236 goto unlock_sig; 1237 1238 if (!unlikely(wo->wo_flags & WNOWAIT)) 1239 *p_code = 0; 1240 1241 uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1242 unlock_sig: 1243 spin_unlock_irq(&p->sighand->siglock); 1244 if (!exit_code) 1245 return 0; 1246 1247 /* 1248 * Now we are pretty sure this task is interesting. 1249 * Make sure it doesn't get reaped out from under us while we 1250 * give up the lock and then examine it below. We don't want to 1251 * keep holding onto the tasklist_lock while we call getrusage and 1252 * possibly take page faults for user memory. 1253 */ 1254 get_task_struct(p); 1255 pid = task_pid_vnr(p); 1256 why = ptrace ? CLD_TRAPPED : CLD_STOPPED; 1257 read_unlock(&tasklist_lock); 1258 sched_annotate_sleep(); 1259 if (wo->wo_rusage) 1260 getrusage(p, RUSAGE_BOTH, wo->wo_rusage); 1261 put_task_struct(p); 1262 1263 if (likely(!(wo->wo_flags & WNOWAIT))) 1264 wo->wo_stat = (exit_code << 8) | 0x7f; 1265 1266 infop = wo->wo_info; 1267 if (infop) { 1268 infop->cause = why; 1269 infop->status = exit_code; 1270 infop->pid = pid; 1271 infop->uid = uid; 1272 } 1273 return pid; 1274 } 1275 1276 /* 1277 * Handle do_wait work for one task in a live, non-stopped state. 1278 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1279 * the lock and this task is uninteresting. If we return nonzero, we have 1280 * released the lock and the system call should return. 1281 */ 1282 static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) 1283 { 1284 struct waitid_info *infop; 1285 pid_t pid; 1286 uid_t uid; 1287 1288 if (!unlikely(wo->wo_flags & WCONTINUED)) 1289 return 0; 1290 1291 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) 1292 return 0; 1293 1294 spin_lock_irq(&p->sighand->siglock); 1295 /* Re-check with the lock held. */ 1296 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { 1297 spin_unlock_irq(&p->sighand->siglock); 1298 return 0; 1299 } 1300 if (!unlikely(wo->wo_flags & WNOWAIT)) 1301 p->signal->flags &= ~SIGNAL_STOP_CONTINUED; 1302 uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1303 spin_unlock_irq(&p->sighand->siglock); 1304 1305 pid = task_pid_vnr(p); 1306 get_task_struct(p); 1307 read_unlock(&tasklist_lock); 1308 sched_annotate_sleep(); 1309 if (wo->wo_rusage) 1310 getrusage(p, RUSAGE_BOTH, wo->wo_rusage); 1311 put_task_struct(p); 1312 1313 infop = wo->wo_info; 1314 if (!infop) { 1315 wo->wo_stat = 0xffff; 1316 } else { 1317 infop->cause = CLD_CONTINUED; 1318 infop->pid = pid; 1319 infop->uid = uid; 1320 infop->status = SIGCONT; 1321 } 1322 return pid; 1323 } 1324 1325 /* 1326 * Consider @p for a wait by @parent. 1327 * 1328 * -ECHILD should be in ->notask_error before the first call. 1329 * Returns nonzero for a final return, when we have unlocked tasklist_lock. 1330 * Returns zero if the search for a child should continue; 1331 * then ->notask_error is 0 if @p is an eligible child, 1332 * or still -ECHILD. 1333 */ 1334 static int wait_consider_task(struct wait_opts *wo, int ptrace, 1335 struct task_struct *p) 1336 { 1337 /* 1338 * We can race with wait_task_zombie() from another thread. 1339 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition 1340 * can't confuse the checks below. 1341 */ 1342 int exit_state = ACCESS_ONCE(p->exit_state); 1343 int ret; 1344 1345 if (unlikely(exit_state == EXIT_DEAD)) 1346 return 0; 1347 1348 ret = eligible_child(wo, ptrace, p); 1349 if (!ret) 1350 return ret; 1351 1352 if (unlikely(exit_state == EXIT_TRACE)) { 1353 /* 1354 * ptrace == 0 means we are the natural parent. In this case 1355 * we should clear notask_error, debugger will notify us. 1356 */ 1357 if (likely(!ptrace)) 1358 wo->notask_error = 0; 1359 return 0; 1360 } 1361 1362 if (likely(!ptrace) && unlikely(p->ptrace)) { 1363 /* 1364 * If it is traced by its real parent's group, just pretend 1365 * the caller is ptrace_do_wait() and reap this child if it 1366 * is zombie. 1367 * 1368 * This also hides group stop state from real parent; otherwise 1369 * a single stop can be reported twice as group and ptrace stop. 1370 * If a ptracer wants to distinguish these two events for its 1371 * own children it should create a separate process which takes 1372 * the role of real parent. 1373 */ 1374 if (!ptrace_reparented(p)) 1375 ptrace = 1; 1376 } 1377 1378 /* slay zombie? */ 1379 if (exit_state == EXIT_ZOMBIE) { 1380 /* we don't reap group leaders with subthreads */ 1381 if (!delay_group_leader(p)) { 1382 /* 1383 * A zombie ptracee is only visible to its ptracer. 1384 * Notification and reaping will be cascaded to the 1385 * real parent when the ptracer detaches. 1386 */ 1387 if (unlikely(ptrace) || likely(!p->ptrace)) 1388 return wait_task_zombie(wo, p); 1389 } 1390 1391 /* 1392 * Allow access to stopped/continued state via zombie by 1393 * falling through. Clearing of notask_error is complex. 1394 * 1395 * When !@ptrace: 1396 * 1397 * If WEXITED is set, notask_error should naturally be 1398 * cleared. If not, subset of WSTOPPED|WCONTINUED is set, 1399 * so, if there are live subthreads, there are events to 1400 * wait for. If all subthreads are dead, it's still safe 1401 * to clear - this function will be called again in finite 1402 * amount time once all the subthreads are released and 1403 * will then return without clearing. 1404 * 1405 * When @ptrace: 1406 * 1407 * Stopped state is per-task and thus can't change once the 1408 * target task dies. Only continued and exited can happen. 1409 * Clear notask_error if WCONTINUED | WEXITED. 1410 */ 1411 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED))) 1412 wo->notask_error = 0; 1413 } else { 1414 /* 1415 * @p is alive and it's gonna stop, continue or exit, so 1416 * there always is something to wait for. 1417 */ 1418 wo->notask_error = 0; 1419 } 1420 1421 /* 1422 * Wait for stopped. Depending on @ptrace, different stopped state 1423 * is used and the two don't interact with each other. 1424 */ 1425 ret = wait_task_stopped(wo, ptrace, p); 1426 if (ret) 1427 return ret; 1428 1429 /* 1430 * Wait for continued. There's only one continued state and the 1431 * ptracer can consume it which can confuse the real parent. Don't 1432 * use WCONTINUED from ptracer. You don't need or want it. 1433 */ 1434 return wait_task_continued(wo, p); 1435 } 1436 1437 /* 1438 * Do the work of do_wait() for one thread in the group, @tsk. 1439 * 1440 * -ECHILD should be in ->notask_error before the first call. 1441 * Returns nonzero for a final return, when we have unlocked tasklist_lock. 1442 * Returns zero if the search for a child should continue; then 1443 * ->notask_error is 0 if there were any eligible children, 1444 * or still -ECHILD. 1445 */ 1446 static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) 1447 { 1448 struct task_struct *p; 1449 1450 list_for_each_entry(p, &tsk->children, sibling) { 1451 int ret = wait_consider_task(wo, 0, p); 1452 1453 if (ret) 1454 return ret; 1455 } 1456 1457 return 0; 1458 } 1459 1460 static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) 1461 { 1462 struct task_struct *p; 1463 1464 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { 1465 int ret = wait_consider_task(wo, 1, p); 1466 1467 if (ret) 1468 return ret; 1469 } 1470 1471 return 0; 1472 } 1473 1474 static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode, 1475 int sync, void *key) 1476 { 1477 struct wait_opts *wo = container_of(wait, struct wait_opts, 1478 child_wait); 1479 struct task_struct *p = key; 1480 1481 if (!eligible_pid(wo, p)) 1482 return 0; 1483 1484 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) 1485 return 0; 1486 1487 return default_wake_function(wait, mode, sync, key); 1488 } 1489 1490 void __wake_up_parent(struct task_struct *p, struct task_struct *parent) 1491 { 1492 __wake_up_sync_key(&parent->signal->wait_chldexit, 1493 TASK_INTERRUPTIBLE, 1, p); 1494 } 1495 1496 static long do_wait(struct wait_opts *wo) 1497 { 1498 struct task_struct *tsk; 1499 int retval; 1500 1501 trace_sched_process_wait(wo->wo_pid); 1502 1503 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); 1504 wo->child_wait.private = current; 1505 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); 1506 repeat: 1507 /* 1508 * If there is nothing that can match our criteria, just get out. 1509 * We will clear ->notask_error to zero if we see any child that 1510 * might later match our criteria, even if we are not able to reap 1511 * it yet. 1512 */ 1513 wo->notask_error = -ECHILD; 1514 if ((wo->wo_type < PIDTYPE_MAX) && 1515 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type]))) 1516 goto notask; 1517 1518 set_current_state(TASK_INTERRUPTIBLE); 1519 read_lock(&tasklist_lock); 1520 tsk = current; 1521 do { 1522 retval = do_wait_thread(wo, tsk); 1523 if (retval) 1524 goto end; 1525 1526 retval = ptrace_do_wait(wo, tsk); 1527 if (retval) 1528 goto end; 1529 1530 if (wo->wo_flags & __WNOTHREAD) 1531 break; 1532 } while_each_thread(current, tsk); 1533 read_unlock(&tasklist_lock); 1534 1535 notask: 1536 retval = wo->notask_error; 1537 if (!retval && !(wo->wo_flags & WNOHANG)) { 1538 retval = -ERESTARTSYS; 1539 if (!signal_pending(current)) { 1540 schedule(); 1541 goto repeat; 1542 } 1543 } 1544 end: 1545 __set_current_state(TASK_RUNNING); 1546 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); 1547 return retval; 1548 } 1549 1550 static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, 1551 int options, struct rusage *ru) 1552 { 1553 struct wait_opts wo; 1554 struct pid *pid = NULL; 1555 enum pid_type type; 1556 long ret; 1557 1558 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED| 1559 __WNOTHREAD|__WCLONE|__WALL)) 1560 return -EINVAL; 1561 if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) 1562 return -EINVAL; 1563 1564 switch (which) { 1565 case P_ALL: 1566 type = PIDTYPE_MAX; 1567 break; 1568 case P_PID: 1569 type = PIDTYPE_PID; 1570 if (upid <= 0) 1571 return -EINVAL; 1572 break; 1573 case P_PGID: 1574 type = PIDTYPE_PGID; 1575 if (upid <= 0) 1576 return -EINVAL; 1577 break; 1578 default: 1579 return -EINVAL; 1580 } 1581 1582 if (type < PIDTYPE_MAX) 1583 pid = find_get_pid(upid); 1584 1585 wo.wo_type = type; 1586 wo.wo_pid = pid; 1587 wo.wo_flags = options; 1588 wo.wo_info = infop; 1589 wo.wo_rusage = ru; 1590 ret = do_wait(&wo); 1591 1592 put_pid(pid); 1593 return ret; 1594 } 1595 1596 SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, 1597 infop, int, options, struct rusage __user *, ru) 1598 { 1599 struct rusage r; 1600 struct waitid_info info = {.status = 0}; 1601 long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL); 1602 int signo = 0; 1603 1604 if (err > 0) { 1605 signo = SIGCHLD; 1606 err = 0; 1607 if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) 1608 return -EFAULT; 1609 } 1610 if (!infop) 1611 return err; 1612 1613 if (!access_ok(VERIFY_WRITE, infop, sizeof(*infop))) 1614 return -EFAULT; 1615 1616 user_access_begin(); 1617 unsafe_put_user(signo, &infop->si_signo, Efault); 1618 unsafe_put_user(0, &infop->si_errno, Efault); 1619 unsafe_put_user(info.cause, &infop->si_code, Efault); 1620 unsafe_put_user(info.pid, &infop->si_pid, Efault); 1621 unsafe_put_user(info.uid, &infop->si_uid, Efault); 1622 unsafe_put_user(info.status, &infop->si_status, Efault); 1623 user_access_end(); 1624 return err; 1625 Efault: 1626 user_access_end(); 1627 return -EFAULT; 1628 } 1629 1630 long kernel_wait4(pid_t upid, int __user *stat_addr, int options, 1631 struct rusage *ru) 1632 { 1633 struct wait_opts wo; 1634 struct pid *pid = NULL; 1635 enum pid_type type; 1636 long ret; 1637 1638 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| 1639 __WNOTHREAD|__WCLONE|__WALL)) 1640 return -EINVAL; 1641 1642 /* -INT_MIN is not defined */ 1643 if (upid == INT_MIN) 1644 return -ESRCH; 1645 1646 if (upid == -1) 1647 type = PIDTYPE_MAX; 1648 else if (upid < 0) { 1649 type = PIDTYPE_PGID; 1650 pid = find_get_pid(-upid); 1651 } else if (upid == 0) { 1652 type = PIDTYPE_PGID; 1653 pid = get_task_pid(current, PIDTYPE_PGID); 1654 } else /* upid > 0 */ { 1655 type = PIDTYPE_PID; 1656 pid = find_get_pid(upid); 1657 } 1658 1659 wo.wo_type = type; 1660 wo.wo_pid = pid; 1661 wo.wo_flags = options | WEXITED; 1662 wo.wo_info = NULL; 1663 wo.wo_stat = 0; 1664 wo.wo_rusage = ru; 1665 ret = do_wait(&wo); 1666 put_pid(pid); 1667 if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr)) 1668 ret = -EFAULT; 1669 1670 return ret; 1671 } 1672 1673 SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, 1674 int, options, struct rusage __user *, ru) 1675 { 1676 struct rusage r; 1677 long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL); 1678 1679 if (err > 0) { 1680 if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) 1681 return -EFAULT; 1682 } 1683 return err; 1684 } 1685 1686 #ifdef __ARCH_WANT_SYS_WAITPID 1687 1688 /* 1689 * sys_waitpid() remains for compatibility. waitpid() should be 1690 * implemented by calling sys_wait4() from libc.a. 1691 */ 1692 SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) 1693 { 1694 return sys_wait4(pid, stat_addr, options, NULL); 1695 } 1696 1697 #endif 1698 1699 #ifdef CONFIG_COMPAT 1700 COMPAT_SYSCALL_DEFINE4(wait4, 1701 compat_pid_t, pid, 1702 compat_uint_t __user *, stat_addr, 1703 int, options, 1704 struct compat_rusage __user *, ru) 1705 { 1706 struct rusage r; 1707 long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL); 1708 if (err > 0) { 1709 if (ru && put_compat_rusage(&r, ru)) 1710 return -EFAULT; 1711 } 1712 return err; 1713 } 1714 1715 COMPAT_SYSCALL_DEFINE5(waitid, 1716 int, which, compat_pid_t, pid, 1717 struct compat_siginfo __user *, infop, int, options, 1718 struct compat_rusage __user *, uru) 1719 { 1720 struct rusage ru; 1721 struct waitid_info info = {.status = 0}; 1722 long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL); 1723 int signo = 0; 1724 if (err > 0) { 1725 signo = SIGCHLD; 1726 err = 0; 1727 if (uru) { 1728 /* kernel_waitid() overwrites everything in ru */ 1729 if (COMPAT_USE_64BIT_TIME) 1730 err = copy_to_user(uru, &ru, sizeof(ru)); 1731 else 1732 err = put_compat_rusage(&ru, uru); 1733 if (err) 1734 return -EFAULT; 1735 } 1736 } 1737 1738 if (!infop) 1739 return err; 1740 1741 if (!access_ok(VERIFY_WRITE, infop, sizeof(*infop))) 1742 return -EFAULT; 1743 1744 user_access_begin(); 1745 unsafe_put_user(signo, &infop->si_signo, Efault); 1746 unsafe_put_user(0, &infop->si_errno, Efault); 1747 unsafe_put_user(info.cause, &infop->si_code, Efault); 1748 unsafe_put_user(info.pid, &infop->si_pid, Efault); 1749 unsafe_put_user(info.uid, &infop->si_uid, Efault); 1750 unsafe_put_user(info.status, &infop->si_status, Efault); 1751 user_access_end(); 1752 return err; 1753 Efault: 1754 user_access_end(); 1755 return -EFAULT; 1756 } 1757 #endif 1758