1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/kernel/exit.c 4 * 5 * Copyright (C) 1991, 1992 Linus Torvalds 6 */ 7 8 #include <linux/mm.h> 9 #include <linux/slab.h> 10 #include <linux/sched/autogroup.h> 11 #include <linux/sched/mm.h> 12 #include <linux/sched/stat.h> 13 #include <linux/sched/task.h> 14 #include <linux/sched/task_stack.h> 15 #include <linux/sched/cputime.h> 16 #include <linux/interrupt.h> 17 #include <linux/module.h> 18 #include <linux/capability.h> 19 #include <linux/completion.h> 20 #include <linux/personality.h> 21 #include <linux/tty.h> 22 #include <linux/iocontext.h> 23 #include <linux/key.h> 24 #include <linux/cpu.h> 25 #include <linux/acct.h> 26 #include <linux/tsacct_kern.h> 27 #include <linux/file.h> 28 #include <linux/fdtable.h> 29 #include <linux/freezer.h> 30 #include <linux/binfmts.h> 31 #include <linux/nsproxy.h> 32 #include <linux/pid_namespace.h> 33 #include <linux/ptrace.h> 34 #include <linux/profile.h> 35 #include <linux/mount.h> 36 #include <linux/proc_fs.h> 37 #include <linux/kthread.h> 38 #include <linux/mempolicy.h> 39 #include <linux/taskstats_kern.h> 40 #include <linux/delayacct.h> 41 #include <linux/cgroup.h> 42 #include <linux/syscalls.h> 43 #include <linux/signal.h> 44 #include <linux/posix-timers.h> 45 #include <linux/cn_proc.h> 46 #include <linux/mutex.h> 47 #include <linux/futex.h> 48 #include <linux/pipe_fs_i.h> 49 #include <linux/audit.h> /* for audit_free() */ 50 #include <linux/resource.h> 51 #include <linux/task_io_accounting_ops.h> 52 #include <linux/blkdev.h> 53 #include <linux/task_work.h> 54 #include <linux/fs_struct.h> 55 #include <linux/init_task.h> 56 #include <linux/perf_event.h> 57 #include <trace/events/sched.h> 58 #include <linux/hw_breakpoint.h> 59 #include <linux/oom.h> 60 #include <linux/writeback.h> 61 #include <linux/shm.h> 62 #include <linux/kcov.h> 63 #include <linux/random.h> 64 #include <linux/rcuwait.h> 65 #include <linux/compat.h> 66 #include <linux/io_uring.h> 67 #include <linux/kprobes.h> 68 #include <linux/rethook.h> 69 70 #include <linux/uaccess.h> 71 #include <asm/unistd.h> 72 #include <asm/mmu_context.h> 73 74 static void __unhash_process(struct task_struct *p, bool group_dead) 75 { 76 nr_threads--; 77 detach_pid(p, PIDTYPE_PID); 78 if (group_dead) { 79 detach_pid(p, PIDTYPE_TGID); 80 detach_pid(p, PIDTYPE_PGID); 81 detach_pid(p, PIDTYPE_SID); 82 83 list_del_rcu(&p->tasks); 84 list_del_init(&p->sibling); 85 __this_cpu_dec(process_counts); 86 } 87 list_del_rcu(&p->thread_group); 88 list_del_rcu(&p->thread_node); 89 } 90 91 /* 92 * This function expects the tasklist_lock write-locked. 93 */ 94 static void __exit_signal(struct task_struct *tsk) 95 { 96 struct signal_struct *sig = tsk->signal; 97 bool group_dead = thread_group_leader(tsk); 98 struct sighand_struct *sighand; 99 struct tty_struct *tty; 100 u64 utime, stime; 101 102 sighand = rcu_dereference_check(tsk->sighand, 103 lockdep_tasklist_lock_is_held()); 104 spin_lock(&sighand->siglock); 105 106 #ifdef CONFIG_POSIX_TIMERS 107 posix_cpu_timers_exit(tsk); 108 if (group_dead) 109 posix_cpu_timers_exit_group(tsk); 110 #endif 111 112 if (group_dead) { 113 tty = sig->tty; 114 sig->tty = NULL; 115 } else { 116 /* 117 * If there is any task waiting for the group exit 118 * then notify it: 119 */ 120 if (sig->notify_count > 0 && !--sig->notify_count) 121 wake_up_process(sig->group_exec_task); 122 123 if (tsk == sig->curr_target) 124 sig->curr_target = next_thread(tsk); 125 } 126 127 add_device_randomness((const void*) &tsk->se.sum_exec_runtime, 128 sizeof(unsigned long long)); 129 130 /* 131 * Accumulate here the counters for all threads as they die. We could 132 * skip the group leader because it is the last user of signal_struct, 133 * but we want to avoid the race with thread_group_cputime() which can 134 * see the empty ->thread_head list. 135 */ 136 task_cputime(tsk, &utime, &stime); 137 write_seqlock(&sig->stats_lock); 138 sig->utime += utime; 139 sig->stime += stime; 140 sig->gtime += task_gtime(tsk); 141 sig->min_flt += tsk->min_flt; 142 sig->maj_flt += tsk->maj_flt; 143 sig->nvcsw += tsk->nvcsw; 144 sig->nivcsw += tsk->nivcsw; 145 sig->inblock += task_io_get_inblock(tsk); 146 sig->oublock += task_io_get_oublock(tsk); 147 task_io_accounting_add(&sig->ioac, &tsk->ioac); 148 sig->sum_sched_runtime += tsk->se.sum_exec_runtime; 149 sig->nr_threads--; 150 __unhash_process(tsk, group_dead); 151 write_sequnlock(&sig->stats_lock); 152 153 /* 154 * Do this under ->siglock, we can race with another thread 155 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. 156 */ 157 flush_sigqueue(&tsk->pending); 158 tsk->sighand = NULL; 159 spin_unlock(&sighand->siglock); 160 161 __cleanup_sighand(sighand); 162 clear_tsk_thread_flag(tsk, TIF_SIGPENDING); 163 if (group_dead) { 164 flush_sigqueue(&sig->shared_pending); 165 tty_kref_put(tty); 166 } 167 } 168 169 static void delayed_put_task_struct(struct rcu_head *rhp) 170 { 171 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); 172 173 kprobe_flush_task(tsk); 174 rethook_flush_task(tsk); 175 perf_event_delayed_put(tsk); 176 trace_sched_process_free(tsk); 177 put_task_struct(tsk); 178 } 179 180 void put_task_struct_rcu_user(struct task_struct *task) 181 { 182 if (refcount_dec_and_test(&task->rcu_users)) 183 call_rcu(&task->rcu, delayed_put_task_struct); 184 } 185 186 void release_task(struct task_struct *p) 187 { 188 struct task_struct *leader; 189 struct pid *thread_pid; 190 int zap_leader; 191 repeat: 192 /* don't need to get the RCU readlock here - the process is dead and 193 * can't be modifying its own credentials. But shut RCU-lockdep up */ 194 rcu_read_lock(); 195 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); 196 rcu_read_unlock(); 197 198 cgroup_release(p); 199 200 write_lock_irq(&tasklist_lock); 201 ptrace_release_task(p); 202 thread_pid = get_pid(p->thread_pid); 203 __exit_signal(p); 204 205 /* 206 * If we are the last non-leader member of the thread 207 * group, and the leader is zombie, then notify the 208 * group leader's parent process. (if it wants notification.) 209 */ 210 zap_leader = 0; 211 leader = p->group_leader; 212 if (leader != p && thread_group_empty(leader) 213 && leader->exit_state == EXIT_ZOMBIE) { 214 /* 215 * If we were the last child thread and the leader has 216 * exited already, and the leader's parent ignores SIGCHLD, 217 * then we are the one who should release the leader. 218 */ 219 zap_leader = do_notify_parent(leader, leader->exit_signal); 220 if (zap_leader) 221 leader->exit_state = EXIT_DEAD; 222 } 223 224 write_unlock_irq(&tasklist_lock); 225 seccomp_filter_release(p); 226 proc_flush_pid(thread_pid); 227 put_pid(thread_pid); 228 release_thread(p); 229 put_task_struct_rcu_user(p); 230 231 p = leader; 232 if (unlikely(zap_leader)) 233 goto repeat; 234 } 235 236 int rcuwait_wake_up(struct rcuwait *w) 237 { 238 int ret = 0; 239 struct task_struct *task; 240 241 rcu_read_lock(); 242 243 /* 244 * Order condition vs @task, such that everything prior to the load 245 * of @task is visible. This is the condition as to why the user called 246 * rcuwait_wake() in the first place. Pairs with set_current_state() 247 * barrier (A) in rcuwait_wait_event(). 248 * 249 * WAIT WAKE 250 * [S] tsk = current [S] cond = true 251 * MB (A) MB (B) 252 * [L] cond [L] tsk 253 */ 254 smp_mb(); /* (B) */ 255 256 task = rcu_dereference(w->task); 257 if (task) 258 ret = wake_up_process(task); 259 rcu_read_unlock(); 260 261 return ret; 262 } 263 EXPORT_SYMBOL_GPL(rcuwait_wake_up); 264 265 /* 266 * Determine if a process group is "orphaned", according to the POSIX 267 * definition in 2.2.2.52. Orphaned process groups are not to be affected 268 * by terminal-generated stop signals. Newly orphaned process groups are 269 * to receive a SIGHUP and a SIGCONT. 270 * 271 * "I ask you, have you ever known what it is to be an orphan?" 272 */ 273 static int will_become_orphaned_pgrp(struct pid *pgrp, 274 struct task_struct *ignored_task) 275 { 276 struct task_struct *p; 277 278 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 279 if ((p == ignored_task) || 280 (p->exit_state && thread_group_empty(p)) || 281 is_global_init(p->real_parent)) 282 continue; 283 284 if (task_pgrp(p->real_parent) != pgrp && 285 task_session(p->real_parent) == task_session(p)) 286 return 0; 287 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 288 289 return 1; 290 } 291 292 int is_current_pgrp_orphaned(void) 293 { 294 int retval; 295 296 read_lock(&tasklist_lock); 297 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); 298 read_unlock(&tasklist_lock); 299 300 return retval; 301 } 302 303 static bool has_stopped_jobs(struct pid *pgrp) 304 { 305 struct task_struct *p; 306 307 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 308 if (p->signal->flags & SIGNAL_STOP_STOPPED) 309 return true; 310 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 311 312 return false; 313 } 314 315 /* 316 * Check to see if any process groups have become orphaned as 317 * a result of our exiting, and if they have any stopped jobs, 318 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 319 */ 320 static void 321 kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) 322 { 323 struct pid *pgrp = task_pgrp(tsk); 324 struct task_struct *ignored_task = tsk; 325 326 if (!parent) 327 /* exit: our father is in a different pgrp than 328 * we are and we were the only connection outside. 329 */ 330 parent = tsk->real_parent; 331 else 332 /* reparent: our child is in a different pgrp than 333 * we are, and it was the only connection outside. 334 */ 335 ignored_task = NULL; 336 337 if (task_pgrp(parent) != pgrp && 338 task_session(parent) == task_session(tsk) && 339 will_become_orphaned_pgrp(pgrp, ignored_task) && 340 has_stopped_jobs(pgrp)) { 341 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); 342 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); 343 } 344 } 345 346 static void coredump_task_exit(struct task_struct *tsk) 347 { 348 struct core_state *core_state; 349 350 /* 351 * Serialize with any possible pending coredump. 352 * We must hold siglock around checking core_state 353 * and setting PF_POSTCOREDUMP. The core-inducing thread 354 * will increment ->nr_threads for each thread in the 355 * group without PF_POSTCOREDUMP set. 356 */ 357 spin_lock_irq(&tsk->sighand->siglock); 358 tsk->flags |= PF_POSTCOREDUMP; 359 core_state = tsk->signal->core_state; 360 spin_unlock_irq(&tsk->sighand->siglock); 361 if (core_state) { 362 struct core_thread self; 363 364 self.task = current; 365 if (self.task->flags & PF_SIGNALED) 366 self.next = xchg(&core_state->dumper.next, &self); 367 else 368 self.task = NULL; 369 /* 370 * Implies mb(), the result of xchg() must be visible 371 * to core_state->dumper. 372 */ 373 if (atomic_dec_and_test(&core_state->nr_threads)) 374 complete(&core_state->startup); 375 376 for (;;) { 377 set_current_state(TASK_UNINTERRUPTIBLE); 378 if (!self.task) /* see coredump_finish() */ 379 break; 380 freezable_schedule(); 381 } 382 __set_current_state(TASK_RUNNING); 383 } 384 } 385 386 #ifdef CONFIG_MEMCG 387 /* 388 * A task is exiting. If it owned this mm, find a new owner for the mm. 389 */ 390 void mm_update_next_owner(struct mm_struct *mm) 391 { 392 struct task_struct *c, *g, *p = current; 393 394 retry: 395 /* 396 * If the exiting or execing task is not the owner, it's 397 * someone else's problem. 398 */ 399 if (mm->owner != p) 400 return; 401 /* 402 * The current owner is exiting/execing and there are no other 403 * candidates. Do not leave the mm pointing to a possibly 404 * freed task structure. 405 */ 406 if (atomic_read(&mm->mm_users) <= 1) { 407 WRITE_ONCE(mm->owner, NULL); 408 return; 409 } 410 411 read_lock(&tasklist_lock); 412 /* 413 * Search in the children 414 */ 415 list_for_each_entry(c, &p->children, sibling) { 416 if (c->mm == mm) 417 goto assign_new_owner; 418 } 419 420 /* 421 * Search in the siblings 422 */ 423 list_for_each_entry(c, &p->real_parent->children, sibling) { 424 if (c->mm == mm) 425 goto assign_new_owner; 426 } 427 428 /* 429 * Search through everything else, we should not get here often. 430 */ 431 for_each_process(g) { 432 if (g->flags & PF_KTHREAD) 433 continue; 434 for_each_thread(g, c) { 435 if (c->mm == mm) 436 goto assign_new_owner; 437 if (c->mm) 438 break; 439 } 440 } 441 read_unlock(&tasklist_lock); 442 /* 443 * We found no owner yet mm_users > 1: this implies that we are 444 * most likely racing with swapoff (try_to_unuse()) or /proc or 445 * ptrace or page migration (get_task_mm()). Mark owner as NULL. 446 */ 447 WRITE_ONCE(mm->owner, NULL); 448 return; 449 450 assign_new_owner: 451 BUG_ON(c == p); 452 get_task_struct(c); 453 /* 454 * The task_lock protects c->mm from changing. 455 * We always want mm->owner->mm == mm 456 */ 457 task_lock(c); 458 /* 459 * Delay read_unlock() till we have the task_lock() 460 * to ensure that c does not slip away underneath us 461 */ 462 read_unlock(&tasklist_lock); 463 if (c->mm != mm) { 464 task_unlock(c); 465 put_task_struct(c); 466 goto retry; 467 } 468 WRITE_ONCE(mm->owner, c); 469 task_unlock(c); 470 put_task_struct(c); 471 } 472 #endif /* CONFIG_MEMCG */ 473 474 /* 475 * Turn us into a lazy TLB process if we 476 * aren't already.. 477 */ 478 static void exit_mm(void) 479 { 480 struct mm_struct *mm = current->mm; 481 482 exit_mm_release(current, mm); 483 if (!mm) 484 return; 485 sync_mm_rss(mm); 486 mmap_read_lock(mm); 487 mmgrab(mm); 488 BUG_ON(mm != current->active_mm); 489 /* more a memory barrier than a real lock */ 490 task_lock(current); 491 /* 492 * When a thread stops operating on an address space, the loop 493 * in membarrier_private_expedited() may not observe that 494 * tsk->mm, and the loop in membarrier_global_expedited() may 495 * not observe a MEMBARRIER_STATE_GLOBAL_EXPEDITED 496 * rq->membarrier_state, so those would not issue an IPI. 497 * Membarrier requires a memory barrier after accessing 498 * user-space memory, before clearing tsk->mm or the 499 * rq->membarrier_state. 500 */ 501 smp_mb__after_spinlock(); 502 local_irq_disable(); 503 current->mm = NULL; 504 membarrier_update_current_mm(NULL); 505 enter_lazy_tlb(mm, current); 506 local_irq_enable(); 507 task_unlock(current); 508 mmap_read_unlock(mm); 509 mm_update_next_owner(mm); 510 mmput(mm); 511 if (test_thread_flag(TIF_MEMDIE)) 512 exit_oom_victim(); 513 } 514 515 static struct task_struct *find_alive_thread(struct task_struct *p) 516 { 517 struct task_struct *t; 518 519 for_each_thread(p, t) { 520 if (!(t->flags & PF_EXITING)) 521 return t; 522 } 523 return NULL; 524 } 525 526 static struct task_struct *find_child_reaper(struct task_struct *father, 527 struct list_head *dead) 528 __releases(&tasklist_lock) 529 __acquires(&tasklist_lock) 530 { 531 struct pid_namespace *pid_ns = task_active_pid_ns(father); 532 struct task_struct *reaper = pid_ns->child_reaper; 533 struct task_struct *p, *n; 534 535 if (likely(reaper != father)) 536 return reaper; 537 538 reaper = find_alive_thread(father); 539 if (reaper) { 540 pid_ns->child_reaper = reaper; 541 return reaper; 542 } 543 544 write_unlock_irq(&tasklist_lock); 545 546 list_for_each_entry_safe(p, n, dead, ptrace_entry) { 547 list_del_init(&p->ptrace_entry); 548 release_task(p); 549 } 550 551 zap_pid_ns_processes(pid_ns); 552 write_lock_irq(&tasklist_lock); 553 554 return father; 555 } 556 557 /* 558 * When we die, we re-parent all our children, and try to: 559 * 1. give them to another thread in our thread group, if such a member exists 560 * 2. give it to the first ancestor process which prctl'd itself as a 561 * child_subreaper for its children (like a service manager) 562 * 3. give it to the init process (PID 1) in our pid namespace 563 */ 564 static struct task_struct *find_new_reaper(struct task_struct *father, 565 struct task_struct *child_reaper) 566 { 567 struct task_struct *thread, *reaper; 568 569 thread = find_alive_thread(father); 570 if (thread) 571 return thread; 572 573 if (father->signal->has_child_subreaper) { 574 unsigned int ns_level = task_pid(father)->level; 575 /* 576 * Find the first ->is_child_subreaper ancestor in our pid_ns. 577 * We can't check reaper != child_reaper to ensure we do not 578 * cross the namespaces, the exiting parent could be injected 579 * by setns() + fork(). 580 * We check pid->level, this is slightly more efficient than 581 * task_active_pid_ns(reaper) != task_active_pid_ns(father). 582 */ 583 for (reaper = father->real_parent; 584 task_pid(reaper)->level == ns_level; 585 reaper = reaper->real_parent) { 586 if (reaper == &init_task) 587 break; 588 if (!reaper->signal->is_child_subreaper) 589 continue; 590 thread = find_alive_thread(reaper); 591 if (thread) 592 return thread; 593 } 594 } 595 596 return child_reaper; 597 } 598 599 /* 600 * Any that need to be release_task'd are put on the @dead list. 601 */ 602 static void reparent_leader(struct task_struct *father, struct task_struct *p, 603 struct list_head *dead) 604 { 605 if (unlikely(p->exit_state == EXIT_DEAD)) 606 return; 607 608 /* We don't want people slaying init. */ 609 p->exit_signal = SIGCHLD; 610 611 /* If it has exited notify the new parent about this child's death. */ 612 if (!p->ptrace && 613 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { 614 if (do_notify_parent(p, p->exit_signal)) { 615 p->exit_state = EXIT_DEAD; 616 list_add(&p->ptrace_entry, dead); 617 } 618 } 619 620 kill_orphaned_pgrp(p, father); 621 } 622 623 /* 624 * This does two things: 625 * 626 * A. Make init inherit all the child processes 627 * B. Check to see if any process groups have become orphaned 628 * as a result of our exiting, and if they have any stopped 629 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 630 */ 631 static void forget_original_parent(struct task_struct *father, 632 struct list_head *dead) 633 { 634 struct task_struct *p, *t, *reaper; 635 636 if (unlikely(!list_empty(&father->ptraced))) 637 exit_ptrace(father, dead); 638 639 /* Can drop and reacquire tasklist_lock */ 640 reaper = find_child_reaper(father, dead); 641 if (list_empty(&father->children)) 642 return; 643 644 reaper = find_new_reaper(father, reaper); 645 list_for_each_entry(p, &father->children, sibling) { 646 for_each_thread(p, t) { 647 RCU_INIT_POINTER(t->real_parent, reaper); 648 BUG_ON((!t->ptrace) != (rcu_access_pointer(t->parent) == father)); 649 if (likely(!t->ptrace)) 650 t->parent = t->real_parent; 651 if (t->pdeath_signal) 652 group_send_sig_info(t->pdeath_signal, 653 SEND_SIG_NOINFO, t, 654 PIDTYPE_TGID); 655 } 656 /* 657 * If this is a threaded reparent there is no need to 658 * notify anyone anything has happened. 659 */ 660 if (!same_thread_group(reaper, father)) 661 reparent_leader(father, p, dead); 662 } 663 list_splice_tail_init(&father->children, &reaper->children); 664 } 665 666 /* 667 * Send signals to all our closest relatives so that they know 668 * to properly mourn us.. 669 */ 670 static void exit_notify(struct task_struct *tsk, int group_dead) 671 { 672 bool autoreap; 673 struct task_struct *p, *n; 674 LIST_HEAD(dead); 675 676 write_lock_irq(&tasklist_lock); 677 forget_original_parent(tsk, &dead); 678 679 if (group_dead) 680 kill_orphaned_pgrp(tsk->group_leader, NULL); 681 682 tsk->exit_state = EXIT_ZOMBIE; 683 if (unlikely(tsk->ptrace)) { 684 int sig = thread_group_leader(tsk) && 685 thread_group_empty(tsk) && 686 !ptrace_reparented(tsk) ? 687 tsk->exit_signal : SIGCHLD; 688 autoreap = do_notify_parent(tsk, sig); 689 } else if (thread_group_leader(tsk)) { 690 autoreap = thread_group_empty(tsk) && 691 do_notify_parent(tsk, tsk->exit_signal); 692 } else { 693 autoreap = true; 694 } 695 696 if (autoreap) { 697 tsk->exit_state = EXIT_DEAD; 698 list_add(&tsk->ptrace_entry, &dead); 699 } 700 701 /* mt-exec, de_thread() is waiting for group leader */ 702 if (unlikely(tsk->signal->notify_count < 0)) 703 wake_up_process(tsk->signal->group_exec_task); 704 write_unlock_irq(&tasklist_lock); 705 706 list_for_each_entry_safe(p, n, &dead, ptrace_entry) { 707 list_del_init(&p->ptrace_entry); 708 release_task(p); 709 } 710 } 711 712 #ifdef CONFIG_DEBUG_STACK_USAGE 713 static void check_stack_usage(void) 714 { 715 static DEFINE_SPINLOCK(low_water_lock); 716 static int lowest_to_date = THREAD_SIZE; 717 unsigned long free; 718 719 free = stack_not_used(current); 720 721 if (free >= lowest_to_date) 722 return; 723 724 spin_lock(&low_water_lock); 725 if (free < lowest_to_date) { 726 pr_info("%s (%d) used greatest stack depth: %lu bytes left\n", 727 current->comm, task_pid_nr(current), free); 728 lowest_to_date = free; 729 } 730 spin_unlock(&low_water_lock); 731 } 732 #else 733 static inline void check_stack_usage(void) {} 734 #endif 735 736 void __noreturn do_exit(long code) 737 { 738 struct task_struct *tsk = current; 739 int group_dead; 740 741 WARN_ON(tsk->plug); 742 743 kcov_task_exit(tsk); 744 745 coredump_task_exit(tsk); 746 ptrace_event(PTRACE_EVENT_EXIT, code); 747 748 validate_creds_for_do_exit(tsk); 749 750 io_uring_files_cancel(); 751 exit_signals(tsk); /* sets PF_EXITING */ 752 753 /* sync mm's RSS info before statistics gathering */ 754 if (tsk->mm) 755 sync_mm_rss(tsk->mm); 756 acct_update_integrals(tsk); 757 group_dead = atomic_dec_and_test(&tsk->signal->live); 758 if (group_dead) { 759 /* 760 * If the last thread of global init has exited, panic 761 * immediately to get a useable coredump. 762 */ 763 if (unlikely(is_global_init(tsk))) 764 panic("Attempted to kill init! exitcode=0x%08x\n", 765 tsk->signal->group_exit_code ?: (int)code); 766 767 #ifdef CONFIG_POSIX_TIMERS 768 hrtimer_cancel(&tsk->signal->real_timer); 769 exit_itimers(tsk->signal); 770 #endif 771 if (tsk->mm) 772 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); 773 } 774 acct_collect(code, group_dead); 775 if (group_dead) 776 tty_audit_exit(); 777 audit_free(tsk); 778 779 tsk->exit_code = code; 780 taskstats_exit(tsk, group_dead); 781 782 exit_mm(); 783 784 if (group_dead) 785 acct_process(); 786 trace_sched_process_exit(tsk); 787 788 exit_sem(tsk); 789 exit_shm(tsk); 790 exit_files(tsk); 791 exit_fs(tsk); 792 if (group_dead) 793 disassociate_ctty(1); 794 exit_task_namespaces(tsk); 795 exit_task_work(tsk); 796 exit_thread(tsk); 797 798 /* 799 * Flush inherited counters to the parent - before the parent 800 * gets woken up by child-exit notifications. 801 * 802 * because of cgroup mode, must be called before cgroup_exit() 803 */ 804 perf_event_exit_task(tsk); 805 806 sched_autogroup_exit_task(tsk); 807 cgroup_exit(tsk); 808 809 /* 810 * FIXME: do that only when needed, using sched_exit tracepoint 811 */ 812 flush_ptrace_hw_breakpoint(tsk); 813 814 exit_tasks_rcu_start(); 815 exit_notify(tsk, group_dead); 816 proc_exit_connector(tsk); 817 mpol_put_task_policy(tsk); 818 #ifdef CONFIG_FUTEX 819 if (unlikely(current->pi_state_cache)) 820 kfree(current->pi_state_cache); 821 #endif 822 /* 823 * Make sure we are holding no locks: 824 */ 825 debug_check_no_locks_held(); 826 827 if (tsk->io_context) 828 exit_io_context(tsk); 829 830 if (tsk->splice_pipe) 831 free_pipe_info(tsk->splice_pipe); 832 833 if (tsk->task_frag.page) 834 put_page(tsk->task_frag.page); 835 836 validate_creds_for_do_exit(tsk); 837 exit_task_stack_account(tsk); 838 839 check_stack_usage(); 840 preempt_disable(); 841 if (tsk->nr_dirtied) 842 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); 843 exit_rcu(); 844 exit_tasks_rcu_finish(); 845 846 lockdep_free_task(tsk); 847 do_task_dead(); 848 } 849 850 void __noreturn make_task_dead(int signr) 851 { 852 /* 853 * Take the task off the cpu after something catastrophic has 854 * happened. 855 * 856 * We can get here from a kernel oops, sometimes with preemption off. 857 * Start by checking for critical errors. 858 * Then fix up important state like USER_DS and preemption. 859 * Then do everything else. 860 */ 861 struct task_struct *tsk = current; 862 863 if (unlikely(in_interrupt())) 864 panic("Aiee, killing interrupt handler!"); 865 if (unlikely(!tsk->pid)) 866 panic("Attempted to kill the idle task!"); 867 868 if (unlikely(in_atomic())) { 869 pr_info("note: %s[%d] exited with preempt_count %d\n", 870 current->comm, task_pid_nr(current), 871 preempt_count()); 872 preempt_count_set(PREEMPT_ENABLED); 873 } 874 875 /* 876 * We're taking recursive faults here in make_task_dead. Safest is to just 877 * leave this task alone and wait for reboot. 878 */ 879 if (unlikely(tsk->flags & PF_EXITING)) { 880 pr_alert("Fixing recursive fault but reboot is needed!\n"); 881 futex_exit_recursive(tsk); 882 tsk->exit_state = EXIT_DEAD; 883 refcount_inc(&tsk->rcu_users); 884 do_task_dead(); 885 } 886 887 do_exit(signr); 888 } 889 890 SYSCALL_DEFINE1(exit, int, error_code) 891 { 892 do_exit((error_code&0xff)<<8); 893 } 894 895 /* 896 * Take down every thread in the group. This is called by fatal signals 897 * as well as by sys_exit_group (below). 898 */ 899 void __noreturn 900 do_group_exit(int exit_code) 901 { 902 struct signal_struct *sig = current->signal; 903 904 if (sig->flags & SIGNAL_GROUP_EXIT) 905 exit_code = sig->group_exit_code; 906 else if (sig->group_exec_task) 907 exit_code = 0; 908 else if (!thread_group_empty(current)) { 909 struct sighand_struct *const sighand = current->sighand; 910 911 spin_lock_irq(&sighand->siglock); 912 if (sig->flags & SIGNAL_GROUP_EXIT) 913 /* Another thread got here before we took the lock. */ 914 exit_code = sig->group_exit_code; 915 else if (sig->group_exec_task) 916 exit_code = 0; 917 else { 918 sig->group_exit_code = exit_code; 919 sig->flags = SIGNAL_GROUP_EXIT; 920 zap_other_threads(current); 921 } 922 spin_unlock_irq(&sighand->siglock); 923 } 924 925 do_exit(exit_code); 926 /* NOTREACHED */ 927 } 928 929 /* 930 * this kills every thread in the thread group. Note that any externally 931 * wait4()-ing process will get the correct exit code - even if this 932 * thread is not the thread group leader. 933 */ 934 SYSCALL_DEFINE1(exit_group, int, error_code) 935 { 936 do_group_exit((error_code & 0xff) << 8); 937 /* NOTREACHED */ 938 return 0; 939 } 940 941 struct waitid_info { 942 pid_t pid; 943 uid_t uid; 944 int status; 945 int cause; 946 }; 947 948 struct wait_opts { 949 enum pid_type wo_type; 950 int wo_flags; 951 struct pid *wo_pid; 952 953 struct waitid_info *wo_info; 954 int wo_stat; 955 struct rusage *wo_rusage; 956 957 wait_queue_entry_t child_wait; 958 int notask_error; 959 }; 960 961 static int eligible_pid(struct wait_opts *wo, struct task_struct *p) 962 { 963 return wo->wo_type == PIDTYPE_MAX || 964 task_pid_type(p, wo->wo_type) == wo->wo_pid; 965 } 966 967 static int 968 eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p) 969 { 970 if (!eligible_pid(wo, p)) 971 return 0; 972 973 /* 974 * Wait for all children (clone and not) if __WALL is set or 975 * if it is traced by us. 976 */ 977 if (ptrace || (wo->wo_flags & __WALL)) 978 return 1; 979 980 /* 981 * Otherwise, wait for clone children *only* if __WCLONE is set; 982 * otherwise, wait for non-clone children *only*. 983 * 984 * Note: a "clone" child here is one that reports to its parent 985 * using a signal other than SIGCHLD, or a non-leader thread which 986 * we can only see if it is traced by us. 987 */ 988 if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) 989 return 0; 990 991 return 1; 992 } 993 994 /* 995 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold 996 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 997 * the lock and this task is uninteresting. If we return nonzero, we have 998 * released the lock and the system call should return. 999 */ 1000 static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) 1001 { 1002 int state, status; 1003 pid_t pid = task_pid_vnr(p); 1004 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1005 struct waitid_info *infop; 1006 1007 if (!likely(wo->wo_flags & WEXITED)) 1008 return 0; 1009 1010 if (unlikely(wo->wo_flags & WNOWAIT)) { 1011 status = (p->signal->flags & SIGNAL_GROUP_EXIT) 1012 ? p->signal->group_exit_code : p->exit_code; 1013 get_task_struct(p); 1014 read_unlock(&tasklist_lock); 1015 sched_annotate_sleep(); 1016 if (wo->wo_rusage) 1017 getrusage(p, RUSAGE_BOTH, wo->wo_rusage); 1018 put_task_struct(p); 1019 goto out_info; 1020 } 1021 /* 1022 * Move the task's state to DEAD/TRACE, only one thread can do this. 1023 */ 1024 state = (ptrace_reparented(p) && thread_group_leader(p)) ? 1025 EXIT_TRACE : EXIT_DEAD; 1026 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) 1027 return 0; 1028 /* 1029 * We own this thread, nobody else can reap it. 1030 */ 1031 read_unlock(&tasklist_lock); 1032 sched_annotate_sleep(); 1033 1034 /* 1035 * Check thread_group_leader() to exclude the traced sub-threads. 1036 */ 1037 if (state == EXIT_DEAD && thread_group_leader(p)) { 1038 struct signal_struct *sig = p->signal; 1039 struct signal_struct *psig = current->signal; 1040 unsigned long maxrss; 1041 u64 tgutime, tgstime; 1042 1043 /* 1044 * The resource counters for the group leader are in its 1045 * own task_struct. Those for dead threads in the group 1046 * are in its signal_struct, as are those for the child 1047 * processes it has previously reaped. All these 1048 * accumulate in the parent's signal_struct c* fields. 1049 * 1050 * We don't bother to take a lock here to protect these 1051 * p->signal fields because the whole thread group is dead 1052 * and nobody can change them. 1053 * 1054 * psig->stats_lock also protects us from our sub-theads 1055 * which can reap other children at the same time. Until 1056 * we change k_getrusage()-like users to rely on this lock 1057 * we have to take ->siglock as well. 1058 * 1059 * We use thread_group_cputime_adjusted() to get times for 1060 * the thread group, which consolidates times for all threads 1061 * in the group including the group leader. 1062 */ 1063 thread_group_cputime_adjusted(p, &tgutime, &tgstime); 1064 spin_lock_irq(¤t->sighand->siglock); 1065 write_seqlock(&psig->stats_lock); 1066 psig->cutime += tgutime + sig->cutime; 1067 psig->cstime += tgstime + sig->cstime; 1068 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime; 1069 psig->cmin_flt += 1070 p->min_flt + sig->min_flt + sig->cmin_flt; 1071 psig->cmaj_flt += 1072 p->maj_flt + sig->maj_flt + sig->cmaj_flt; 1073 psig->cnvcsw += 1074 p->nvcsw + sig->nvcsw + sig->cnvcsw; 1075 psig->cnivcsw += 1076 p->nivcsw + sig->nivcsw + sig->cnivcsw; 1077 psig->cinblock += 1078 task_io_get_inblock(p) + 1079 sig->inblock + sig->cinblock; 1080 psig->coublock += 1081 task_io_get_oublock(p) + 1082 sig->oublock + sig->coublock; 1083 maxrss = max(sig->maxrss, sig->cmaxrss); 1084 if (psig->cmaxrss < maxrss) 1085 psig->cmaxrss = maxrss; 1086 task_io_accounting_add(&psig->ioac, &p->ioac); 1087 task_io_accounting_add(&psig->ioac, &sig->ioac); 1088 write_sequnlock(&psig->stats_lock); 1089 spin_unlock_irq(¤t->sighand->siglock); 1090 } 1091 1092 if (wo->wo_rusage) 1093 getrusage(p, RUSAGE_BOTH, wo->wo_rusage); 1094 status = (p->signal->flags & SIGNAL_GROUP_EXIT) 1095 ? p->signal->group_exit_code : p->exit_code; 1096 wo->wo_stat = status; 1097 1098 if (state == EXIT_TRACE) { 1099 write_lock_irq(&tasklist_lock); 1100 /* We dropped tasklist, ptracer could die and untrace */ 1101 ptrace_unlink(p); 1102 1103 /* If parent wants a zombie, don't release it now */ 1104 state = EXIT_ZOMBIE; 1105 if (do_notify_parent(p, p->exit_signal)) 1106 state = EXIT_DEAD; 1107 p->exit_state = state; 1108 write_unlock_irq(&tasklist_lock); 1109 } 1110 if (state == EXIT_DEAD) 1111 release_task(p); 1112 1113 out_info: 1114 infop = wo->wo_info; 1115 if (infop) { 1116 if ((status & 0x7f) == 0) { 1117 infop->cause = CLD_EXITED; 1118 infop->status = status >> 8; 1119 } else { 1120 infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; 1121 infop->status = status & 0x7f; 1122 } 1123 infop->pid = pid; 1124 infop->uid = uid; 1125 } 1126 1127 return pid; 1128 } 1129 1130 static int *task_stopped_code(struct task_struct *p, bool ptrace) 1131 { 1132 if (ptrace) { 1133 if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING)) 1134 return &p->exit_code; 1135 } else { 1136 if (p->signal->flags & SIGNAL_STOP_STOPPED) 1137 return &p->signal->group_exit_code; 1138 } 1139 return NULL; 1140 } 1141 1142 /** 1143 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED 1144 * @wo: wait options 1145 * @ptrace: is the wait for ptrace 1146 * @p: task to wait for 1147 * 1148 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED. 1149 * 1150 * CONTEXT: 1151 * read_lock(&tasklist_lock), which is released if return value is 1152 * non-zero. Also, grabs and releases @p->sighand->siglock. 1153 * 1154 * RETURNS: 1155 * 0 if wait condition didn't exist and search for other wait conditions 1156 * should continue. Non-zero return, -errno on failure and @p's pid on 1157 * success, implies that tasklist_lock is released and wait condition 1158 * search should terminate. 1159 */ 1160 static int wait_task_stopped(struct wait_opts *wo, 1161 int ptrace, struct task_struct *p) 1162 { 1163 struct waitid_info *infop; 1164 int exit_code, *p_code, why; 1165 uid_t uid = 0; /* unneeded, required by compiler */ 1166 pid_t pid; 1167 1168 /* 1169 * Traditionally we see ptrace'd stopped tasks regardless of options. 1170 */ 1171 if (!ptrace && !(wo->wo_flags & WUNTRACED)) 1172 return 0; 1173 1174 if (!task_stopped_code(p, ptrace)) 1175 return 0; 1176 1177 exit_code = 0; 1178 spin_lock_irq(&p->sighand->siglock); 1179 1180 p_code = task_stopped_code(p, ptrace); 1181 if (unlikely(!p_code)) 1182 goto unlock_sig; 1183 1184 exit_code = *p_code; 1185 if (!exit_code) 1186 goto unlock_sig; 1187 1188 if (!unlikely(wo->wo_flags & WNOWAIT)) 1189 *p_code = 0; 1190 1191 uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1192 unlock_sig: 1193 spin_unlock_irq(&p->sighand->siglock); 1194 if (!exit_code) 1195 return 0; 1196 1197 /* 1198 * Now we are pretty sure this task is interesting. 1199 * Make sure it doesn't get reaped out from under us while we 1200 * give up the lock and then examine it below. We don't want to 1201 * keep holding onto the tasklist_lock while we call getrusage and 1202 * possibly take page faults for user memory. 1203 */ 1204 get_task_struct(p); 1205 pid = task_pid_vnr(p); 1206 why = ptrace ? CLD_TRAPPED : CLD_STOPPED; 1207 read_unlock(&tasklist_lock); 1208 sched_annotate_sleep(); 1209 if (wo->wo_rusage) 1210 getrusage(p, RUSAGE_BOTH, wo->wo_rusage); 1211 put_task_struct(p); 1212 1213 if (likely(!(wo->wo_flags & WNOWAIT))) 1214 wo->wo_stat = (exit_code << 8) | 0x7f; 1215 1216 infop = wo->wo_info; 1217 if (infop) { 1218 infop->cause = why; 1219 infop->status = exit_code; 1220 infop->pid = pid; 1221 infop->uid = uid; 1222 } 1223 return pid; 1224 } 1225 1226 /* 1227 * Handle do_wait work for one task in a live, non-stopped state. 1228 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1229 * the lock and this task is uninteresting. If we return nonzero, we have 1230 * released the lock and the system call should return. 1231 */ 1232 static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) 1233 { 1234 struct waitid_info *infop; 1235 pid_t pid; 1236 uid_t uid; 1237 1238 if (!unlikely(wo->wo_flags & WCONTINUED)) 1239 return 0; 1240 1241 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) 1242 return 0; 1243 1244 spin_lock_irq(&p->sighand->siglock); 1245 /* Re-check with the lock held. */ 1246 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { 1247 spin_unlock_irq(&p->sighand->siglock); 1248 return 0; 1249 } 1250 if (!unlikely(wo->wo_flags & WNOWAIT)) 1251 p->signal->flags &= ~SIGNAL_STOP_CONTINUED; 1252 uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1253 spin_unlock_irq(&p->sighand->siglock); 1254 1255 pid = task_pid_vnr(p); 1256 get_task_struct(p); 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 infop = wo->wo_info; 1264 if (!infop) { 1265 wo->wo_stat = 0xffff; 1266 } else { 1267 infop->cause = CLD_CONTINUED; 1268 infop->pid = pid; 1269 infop->uid = uid; 1270 infop->status = SIGCONT; 1271 } 1272 return pid; 1273 } 1274 1275 /* 1276 * Consider @p for a wait by @parent. 1277 * 1278 * -ECHILD should be in ->notask_error before the first call. 1279 * Returns nonzero for a final return, when we have unlocked tasklist_lock. 1280 * Returns zero if the search for a child should continue; 1281 * then ->notask_error is 0 if @p is an eligible child, 1282 * or still -ECHILD. 1283 */ 1284 static int wait_consider_task(struct wait_opts *wo, int ptrace, 1285 struct task_struct *p) 1286 { 1287 /* 1288 * We can race with wait_task_zombie() from another thread. 1289 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition 1290 * can't confuse the checks below. 1291 */ 1292 int exit_state = READ_ONCE(p->exit_state); 1293 int ret; 1294 1295 if (unlikely(exit_state == EXIT_DEAD)) 1296 return 0; 1297 1298 ret = eligible_child(wo, ptrace, p); 1299 if (!ret) 1300 return ret; 1301 1302 if (unlikely(exit_state == EXIT_TRACE)) { 1303 /* 1304 * ptrace == 0 means we are the natural parent. In this case 1305 * we should clear notask_error, debugger will notify us. 1306 */ 1307 if (likely(!ptrace)) 1308 wo->notask_error = 0; 1309 return 0; 1310 } 1311 1312 if (likely(!ptrace) && unlikely(p->ptrace)) { 1313 /* 1314 * If it is traced by its real parent's group, just pretend 1315 * the caller is ptrace_do_wait() and reap this child if it 1316 * is zombie. 1317 * 1318 * This also hides group stop state from real parent; otherwise 1319 * a single stop can be reported twice as group and ptrace stop. 1320 * If a ptracer wants to distinguish these two events for its 1321 * own children it should create a separate process which takes 1322 * the role of real parent. 1323 */ 1324 if (!ptrace_reparented(p)) 1325 ptrace = 1; 1326 } 1327 1328 /* slay zombie? */ 1329 if (exit_state == EXIT_ZOMBIE) { 1330 /* we don't reap group leaders with subthreads */ 1331 if (!delay_group_leader(p)) { 1332 /* 1333 * A zombie ptracee is only visible to its ptracer. 1334 * Notification and reaping will be cascaded to the 1335 * real parent when the ptracer detaches. 1336 */ 1337 if (unlikely(ptrace) || likely(!p->ptrace)) 1338 return wait_task_zombie(wo, p); 1339 } 1340 1341 /* 1342 * Allow access to stopped/continued state via zombie by 1343 * falling through. Clearing of notask_error is complex. 1344 * 1345 * When !@ptrace: 1346 * 1347 * If WEXITED is set, notask_error should naturally be 1348 * cleared. If not, subset of WSTOPPED|WCONTINUED is set, 1349 * so, if there are live subthreads, there are events to 1350 * wait for. If all subthreads are dead, it's still safe 1351 * to clear - this function will be called again in finite 1352 * amount time once all the subthreads are released and 1353 * will then return without clearing. 1354 * 1355 * When @ptrace: 1356 * 1357 * Stopped state is per-task and thus can't change once the 1358 * target task dies. Only continued and exited can happen. 1359 * Clear notask_error if WCONTINUED | WEXITED. 1360 */ 1361 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED))) 1362 wo->notask_error = 0; 1363 } else { 1364 /* 1365 * @p is alive and it's gonna stop, continue or exit, so 1366 * there always is something to wait for. 1367 */ 1368 wo->notask_error = 0; 1369 } 1370 1371 /* 1372 * Wait for stopped. Depending on @ptrace, different stopped state 1373 * is used and the two don't interact with each other. 1374 */ 1375 ret = wait_task_stopped(wo, ptrace, p); 1376 if (ret) 1377 return ret; 1378 1379 /* 1380 * Wait for continued. There's only one continued state and the 1381 * ptracer can consume it which can confuse the real parent. Don't 1382 * use WCONTINUED from ptracer. You don't need or want it. 1383 */ 1384 return wait_task_continued(wo, p); 1385 } 1386 1387 /* 1388 * Do the work of do_wait() for one thread in the group, @tsk. 1389 * 1390 * -ECHILD should be in ->notask_error before the first call. 1391 * Returns nonzero for a final return, when we have unlocked tasklist_lock. 1392 * Returns zero if the search for a child should continue; then 1393 * ->notask_error is 0 if there were any eligible children, 1394 * or still -ECHILD. 1395 */ 1396 static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) 1397 { 1398 struct task_struct *p; 1399 1400 list_for_each_entry(p, &tsk->children, sibling) { 1401 int ret = wait_consider_task(wo, 0, p); 1402 1403 if (ret) 1404 return ret; 1405 } 1406 1407 return 0; 1408 } 1409 1410 static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) 1411 { 1412 struct task_struct *p; 1413 1414 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { 1415 int ret = wait_consider_task(wo, 1, p); 1416 1417 if (ret) 1418 return ret; 1419 } 1420 1421 return 0; 1422 } 1423 1424 static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode, 1425 int sync, void *key) 1426 { 1427 struct wait_opts *wo = container_of(wait, struct wait_opts, 1428 child_wait); 1429 struct task_struct *p = key; 1430 1431 if (!eligible_pid(wo, p)) 1432 return 0; 1433 1434 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) 1435 return 0; 1436 1437 return default_wake_function(wait, mode, sync, key); 1438 } 1439 1440 void __wake_up_parent(struct task_struct *p, struct task_struct *parent) 1441 { 1442 __wake_up_sync_key(&parent->signal->wait_chldexit, 1443 TASK_INTERRUPTIBLE, p); 1444 } 1445 1446 static bool is_effectively_child(struct wait_opts *wo, bool ptrace, 1447 struct task_struct *target) 1448 { 1449 struct task_struct *parent = 1450 !ptrace ? target->real_parent : target->parent; 1451 1452 return current == parent || (!(wo->wo_flags & __WNOTHREAD) && 1453 same_thread_group(current, parent)); 1454 } 1455 1456 /* 1457 * Optimization for waiting on PIDTYPE_PID. No need to iterate through child 1458 * and tracee lists to find the target task. 1459 */ 1460 static int do_wait_pid(struct wait_opts *wo) 1461 { 1462 bool ptrace; 1463 struct task_struct *target; 1464 int retval; 1465 1466 ptrace = false; 1467 target = pid_task(wo->wo_pid, PIDTYPE_TGID); 1468 if (target && is_effectively_child(wo, ptrace, target)) { 1469 retval = wait_consider_task(wo, ptrace, target); 1470 if (retval) 1471 return retval; 1472 } 1473 1474 ptrace = true; 1475 target = pid_task(wo->wo_pid, PIDTYPE_PID); 1476 if (target && target->ptrace && 1477 is_effectively_child(wo, ptrace, target)) { 1478 retval = wait_consider_task(wo, ptrace, target); 1479 if (retval) 1480 return retval; 1481 } 1482 1483 return 0; 1484 } 1485 1486 static long do_wait(struct wait_opts *wo) 1487 { 1488 int retval; 1489 1490 trace_sched_process_wait(wo->wo_pid); 1491 1492 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); 1493 wo->child_wait.private = current; 1494 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); 1495 repeat: 1496 /* 1497 * If there is nothing that can match our criteria, just get out. 1498 * We will clear ->notask_error to zero if we see any child that 1499 * might later match our criteria, even if we are not able to reap 1500 * it yet. 1501 */ 1502 wo->notask_error = -ECHILD; 1503 if ((wo->wo_type < PIDTYPE_MAX) && 1504 (!wo->wo_pid || !pid_has_task(wo->wo_pid, wo->wo_type))) 1505 goto notask; 1506 1507 set_current_state(TASK_INTERRUPTIBLE); 1508 read_lock(&tasklist_lock); 1509 1510 if (wo->wo_type == PIDTYPE_PID) { 1511 retval = do_wait_pid(wo); 1512 if (retval) 1513 goto end; 1514 } else { 1515 struct task_struct *tsk = current; 1516 1517 do { 1518 retval = do_wait_thread(wo, tsk); 1519 if (retval) 1520 goto end; 1521 1522 retval = ptrace_do_wait(wo, tsk); 1523 if (retval) 1524 goto end; 1525 1526 if (wo->wo_flags & __WNOTHREAD) 1527 break; 1528 } while_each_thread(current, tsk); 1529 } 1530 read_unlock(&tasklist_lock); 1531 1532 notask: 1533 retval = wo->notask_error; 1534 if (!retval && !(wo->wo_flags & WNOHANG)) { 1535 retval = -ERESTARTSYS; 1536 if (!signal_pending(current)) { 1537 schedule(); 1538 goto repeat; 1539 } 1540 } 1541 end: 1542 __set_current_state(TASK_RUNNING); 1543 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); 1544 return retval; 1545 } 1546 1547 static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, 1548 int options, struct rusage *ru) 1549 { 1550 struct wait_opts wo; 1551 struct pid *pid = NULL; 1552 enum pid_type type; 1553 long ret; 1554 unsigned int f_flags = 0; 1555 1556 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED| 1557 __WNOTHREAD|__WCLONE|__WALL)) 1558 return -EINVAL; 1559 if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) 1560 return -EINVAL; 1561 1562 switch (which) { 1563 case P_ALL: 1564 type = PIDTYPE_MAX; 1565 break; 1566 case P_PID: 1567 type = PIDTYPE_PID; 1568 if (upid <= 0) 1569 return -EINVAL; 1570 1571 pid = find_get_pid(upid); 1572 break; 1573 case P_PGID: 1574 type = PIDTYPE_PGID; 1575 if (upid < 0) 1576 return -EINVAL; 1577 1578 if (upid) 1579 pid = find_get_pid(upid); 1580 else 1581 pid = get_task_pid(current, PIDTYPE_PGID); 1582 break; 1583 case P_PIDFD: 1584 type = PIDTYPE_PID; 1585 if (upid < 0) 1586 return -EINVAL; 1587 1588 pid = pidfd_get_pid(upid, &f_flags); 1589 if (IS_ERR(pid)) 1590 return PTR_ERR(pid); 1591 1592 break; 1593 default: 1594 return -EINVAL; 1595 } 1596 1597 wo.wo_type = type; 1598 wo.wo_pid = pid; 1599 wo.wo_flags = options; 1600 wo.wo_info = infop; 1601 wo.wo_rusage = ru; 1602 if (f_flags & O_NONBLOCK) 1603 wo.wo_flags |= WNOHANG; 1604 1605 ret = do_wait(&wo); 1606 if (!ret && !(options & WNOHANG) && (f_flags & O_NONBLOCK)) 1607 ret = -EAGAIN; 1608 1609 put_pid(pid); 1610 return ret; 1611 } 1612 1613 SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, 1614 infop, int, options, struct rusage __user *, ru) 1615 { 1616 struct rusage r; 1617 struct waitid_info info = {.status = 0}; 1618 long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL); 1619 int signo = 0; 1620 1621 if (err > 0) { 1622 signo = SIGCHLD; 1623 err = 0; 1624 if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) 1625 return -EFAULT; 1626 } 1627 if (!infop) 1628 return err; 1629 1630 if (!user_write_access_begin(infop, sizeof(*infop))) 1631 return -EFAULT; 1632 1633 unsafe_put_user(signo, &infop->si_signo, Efault); 1634 unsafe_put_user(0, &infop->si_errno, Efault); 1635 unsafe_put_user(info.cause, &infop->si_code, Efault); 1636 unsafe_put_user(info.pid, &infop->si_pid, Efault); 1637 unsafe_put_user(info.uid, &infop->si_uid, Efault); 1638 unsafe_put_user(info.status, &infop->si_status, Efault); 1639 user_write_access_end(); 1640 return err; 1641 Efault: 1642 user_write_access_end(); 1643 return -EFAULT; 1644 } 1645 1646 long kernel_wait4(pid_t upid, int __user *stat_addr, int options, 1647 struct rusage *ru) 1648 { 1649 struct wait_opts wo; 1650 struct pid *pid = NULL; 1651 enum pid_type type; 1652 long ret; 1653 1654 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| 1655 __WNOTHREAD|__WCLONE|__WALL)) 1656 return -EINVAL; 1657 1658 /* -INT_MIN is not defined */ 1659 if (upid == INT_MIN) 1660 return -ESRCH; 1661 1662 if (upid == -1) 1663 type = PIDTYPE_MAX; 1664 else if (upid < 0) { 1665 type = PIDTYPE_PGID; 1666 pid = find_get_pid(-upid); 1667 } else if (upid == 0) { 1668 type = PIDTYPE_PGID; 1669 pid = get_task_pid(current, PIDTYPE_PGID); 1670 } else /* upid > 0 */ { 1671 type = PIDTYPE_PID; 1672 pid = find_get_pid(upid); 1673 } 1674 1675 wo.wo_type = type; 1676 wo.wo_pid = pid; 1677 wo.wo_flags = options | WEXITED; 1678 wo.wo_info = NULL; 1679 wo.wo_stat = 0; 1680 wo.wo_rusage = ru; 1681 ret = do_wait(&wo); 1682 put_pid(pid); 1683 if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr)) 1684 ret = -EFAULT; 1685 1686 return ret; 1687 } 1688 1689 int kernel_wait(pid_t pid, int *stat) 1690 { 1691 struct wait_opts wo = { 1692 .wo_type = PIDTYPE_PID, 1693 .wo_pid = find_get_pid(pid), 1694 .wo_flags = WEXITED, 1695 }; 1696 int ret; 1697 1698 ret = do_wait(&wo); 1699 if (ret > 0 && wo.wo_stat) 1700 *stat = wo.wo_stat; 1701 put_pid(wo.wo_pid); 1702 return ret; 1703 } 1704 1705 SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, 1706 int, options, struct rusage __user *, ru) 1707 { 1708 struct rusage r; 1709 long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL); 1710 1711 if (err > 0) { 1712 if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) 1713 return -EFAULT; 1714 } 1715 return err; 1716 } 1717 1718 #ifdef __ARCH_WANT_SYS_WAITPID 1719 1720 /* 1721 * sys_waitpid() remains for compatibility. waitpid() should be 1722 * implemented by calling sys_wait4() from libc.a. 1723 */ 1724 SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) 1725 { 1726 return kernel_wait4(pid, stat_addr, options, NULL); 1727 } 1728 1729 #endif 1730 1731 #ifdef CONFIG_COMPAT 1732 COMPAT_SYSCALL_DEFINE4(wait4, 1733 compat_pid_t, pid, 1734 compat_uint_t __user *, stat_addr, 1735 int, options, 1736 struct compat_rusage __user *, ru) 1737 { 1738 struct rusage r; 1739 long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL); 1740 if (err > 0) { 1741 if (ru && put_compat_rusage(&r, ru)) 1742 return -EFAULT; 1743 } 1744 return err; 1745 } 1746 1747 COMPAT_SYSCALL_DEFINE5(waitid, 1748 int, which, compat_pid_t, pid, 1749 struct compat_siginfo __user *, infop, int, options, 1750 struct compat_rusage __user *, uru) 1751 { 1752 struct rusage ru; 1753 struct waitid_info info = {.status = 0}; 1754 long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL); 1755 int signo = 0; 1756 if (err > 0) { 1757 signo = SIGCHLD; 1758 err = 0; 1759 if (uru) { 1760 /* kernel_waitid() overwrites everything in ru */ 1761 if (COMPAT_USE_64BIT_TIME) 1762 err = copy_to_user(uru, &ru, sizeof(ru)); 1763 else 1764 err = put_compat_rusage(&ru, uru); 1765 if (err) 1766 return -EFAULT; 1767 } 1768 } 1769 1770 if (!infop) 1771 return err; 1772 1773 if (!user_write_access_begin(infop, sizeof(*infop))) 1774 return -EFAULT; 1775 1776 unsafe_put_user(signo, &infop->si_signo, Efault); 1777 unsafe_put_user(0, &infop->si_errno, Efault); 1778 unsafe_put_user(info.cause, &infop->si_code, Efault); 1779 unsafe_put_user(info.pid, &infop->si_pid, Efault); 1780 unsafe_put_user(info.uid, &infop->si_uid, Efault); 1781 unsafe_put_user(info.status, &infop->si_status, Efault); 1782 user_write_access_end(); 1783 return err; 1784 Efault: 1785 user_write_access_end(); 1786 return -EFAULT; 1787 } 1788 #endif 1789 1790 /** 1791 * thread_group_exited - check that a thread group has exited 1792 * @pid: tgid of thread group to be checked. 1793 * 1794 * Test if the thread group represented by tgid has exited (all 1795 * threads are zombies, dead or completely gone). 1796 * 1797 * Return: true if the thread group has exited. false otherwise. 1798 */ 1799 bool thread_group_exited(struct pid *pid) 1800 { 1801 struct task_struct *task; 1802 bool exited; 1803 1804 rcu_read_lock(); 1805 task = pid_task(pid, PIDTYPE_PID); 1806 exited = !task || 1807 (READ_ONCE(task->exit_state) && thread_group_empty(task)); 1808 rcu_read_unlock(); 1809 1810 return exited; 1811 } 1812 EXPORT_SYMBOL(thread_group_exited); 1813 1814 __weak void abort(void) 1815 { 1816 BUG(); 1817 1818 /* if that doesn't kill us, halt */ 1819 panic("Oops failed to kill thread"); 1820 } 1821 EXPORT_SYMBOL(abort); 1822