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/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 #include <linux/io_uring.h> 66 #include <linux/kprobes.h> 67 #include <linux/rethook.h> 68 69 #include <linux/uaccess.h> 70 #include <asm/unistd.h> 71 #include <asm/mmu_context.h> 72 73 static void __unhash_process(struct task_struct *p, bool group_dead) 74 { 75 nr_threads--; 76 detach_pid(p, PIDTYPE_PID); 77 if (group_dead) { 78 detach_pid(p, PIDTYPE_TGID); 79 detach_pid(p, PIDTYPE_PGID); 80 detach_pid(p, PIDTYPE_SID); 81 82 list_del_rcu(&p->tasks); 83 list_del_init(&p->sibling); 84 __this_cpu_dec(process_counts); 85 } 86 list_del_rcu(&p->thread_group); 87 list_del_rcu(&p->thread_node); 88 } 89 90 /* 91 * This function expects the tasklist_lock write-locked. 92 */ 93 static void __exit_signal(struct task_struct *tsk) 94 { 95 struct signal_struct *sig = tsk->signal; 96 bool group_dead = thread_group_leader(tsk); 97 struct sighand_struct *sighand; 98 struct tty_struct *tty; 99 u64 utime, stime; 100 101 sighand = rcu_dereference_check(tsk->sighand, 102 lockdep_tasklist_lock_is_held()); 103 spin_lock(&sighand->siglock); 104 105 #ifdef CONFIG_POSIX_TIMERS 106 posix_cpu_timers_exit(tsk); 107 if (group_dead) 108 posix_cpu_timers_exit_group(tsk); 109 #endif 110 111 if (group_dead) { 112 tty = sig->tty; 113 sig->tty = NULL; 114 } else { 115 /* 116 * If there is any task waiting for the group exit 117 * then notify it: 118 */ 119 if (sig->notify_count > 0 && !--sig->notify_count) 120 wake_up_process(sig->group_exec_task); 121 122 if (tsk == sig->curr_target) 123 sig->curr_target = next_thread(tsk); 124 } 125 126 add_device_randomness((const void*) &tsk->se.sum_exec_runtime, 127 sizeof(unsigned long long)); 128 129 /* 130 * Accumulate here the counters for all threads as they die. We could 131 * skip the group leader because it is the last user of signal_struct, 132 * but we want to avoid the race with thread_group_cputime() which can 133 * see the empty ->thread_head list. 134 */ 135 task_cputime(tsk, &utime, &stime); 136 write_seqlock(&sig->stats_lock); 137 sig->utime += utime; 138 sig->stime += stime; 139 sig->gtime += task_gtime(tsk); 140 sig->min_flt += tsk->min_flt; 141 sig->maj_flt += tsk->maj_flt; 142 sig->nvcsw += tsk->nvcsw; 143 sig->nivcsw += tsk->nivcsw; 144 sig->inblock += task_io_get_inblock(tsk); 145 sig->oublock += task_io_get_oublock(tsk); 146 task_io_accounting_add(&sig->ioac, &tsk->ioac); 147 sig->sum_sched_runtime += tsk->se.sum_exec_runtime; 148 sig->nr_threads--; 149 __unhash_process(tsk, group_dead); 150 write_sequnlock(&sig->stats_lock); 151 152 /* 153 * Do this under ->siglock, we can race with another thread 154 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. 155 */ 156 flush_sigqueue(&tsk->pending); 157 tsk->sighand = NULL; 158 spin_unlock(&sighand->siglock); 159 160 __cleanup_sighand(sighand); 161 clear_tsk_thread_flag(tsk, TIF_SIGPENDING); 162 if (group_dead) { 163 flush_sigqueue(&sig->shared_pending); 164 tty_kref_put(tty); 165 } 166 } 167 168 static void delayed_put_task_struct(struct rcu_head *rhp) 169 { 170 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); 171 172 kprobe_flush_task(tsk); 173 rethook_flush_task(tsk); 174 perf_event_delayed_put(tsk); 175 trace_sched_process_free(tsk); 176 put_task_struct(tsk); 177 } 178 179 void put_task_struct_rcu_user(struct task_struct *task) 180 { 181 if (refcount_dec_and_test(&task->rcu_users)) 182 call_rcu(&task->rcu, delayed_put_task_struct); 183 } 184 185 void release_task(struct task_struct *p) 186 { 187 struct task_struct *leader; 188 struct pid *thread_pid; 189 int zap_leader; 190 repeat: 191 /* don't need to get the RCU readlock here - the process is dead and 192 * can't be modifying its own credentials. But shut RCU-lockdep up */ 193 rcu_read_lock(); 194 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); 195 rcu_read_unlock(); 196 197 cgroup_release(p); 198 199 write_lock_irq(&tasklist_lock); 200 ptrace_release_task(p); 201 thread_pid = get_pid(p->thread_pid); 202 __exit_signal(p); 203 204 /* 205 * If we are the last non-leader member of the thread 206 * group, and the leader is zombie, then notify the 207 * group leader's parent process. (if it wants notification.) 208 */ 209 zap_leader = 0; 210 leader = p->group_leader; 211 if (leader != p && thread_group_empty(leader) 212 && leader->exit_state == EXIT_ZOMBIE) { 213 /* 214 * If we were the last child thread and the leader has 215 * exited already, and the leader's parent ignores SIGCHLD, 216 * then we are the one who should release the leader. 217 */ 218 zap_leader = do_notify_parent(leader, leader->exit_signal); 219 if (zap_leader) 220 leader->exit_state = EXIT_DEAD; 221 } 222 223 write_unlock_irq(&tasklist_lock); 224 seccomp_filter_release(p); 225 proc_flush_pid(thread_pid); 226 put_pid(thread_pid); 227 release_thread(p); 228 put_task_struct_rcu_user(p); 229 230 p = leader; 231 if (unlikely(zap_leader)) 232 goto repeat; 233 } 234 235 int rcuwait_wake_up(struct rcuwait *w) 236 { 237 int ret = 0; 238 struct task_struct *task; 239 240 rcu_read_lock(); 241 242 /* 243 * Order condition vs @task, such that everything prior to the load 244 * of @task is visible. This is the condition as to why the user called 245 * rcuwait_wake() in the first place. Pairs with set_current_state() 246 * barrier (A) in rcuwait_wait_event(). 247 * 248 * WAIT WAKE 249 * [S] tsk = current [S] cond = true 250 * MB (A) MB (B) 251 * [L] cond [L] tsk 252 */ 253 smp_mb(); /* (B) */ 254 255 task = rcu_dereference(w->task); 256 if (task) 257 ret = wake_up_process(task); 258 rcu_read_unlock(); 259 260 return ret; 261 } 262 EXPORT_SYMBOL_GPL(rcuwait_wake_up); 263 264 /* 265 * Determine if a process group is "orphaned", according to the POSIX 266 * definition in 2.2.2.52. Orphaned process groups are not to be affected 267 * by terminal-generated stop signals. Newly orphaned process groups are 268 * to receive a SIGHUP and a SIGCONT. 269 * 270 * "I ask you, have you ever known what it is to be an orphan?" 271 */ 272 static int will_become_orphaned_pgrp(struct pid *pgrp, 273 struct task_struct *ignored_task) 274 { 275 struct task_struct *p; 276 277 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 278 if ((p == ignored_task) || 279 (p->exit_state && thread_group_empty(p)) || 280 is_global_init(p->real_parent)) 281 continue; 282 283 if (task_pgrp(p->real_parent) != pgrp && 284 task_session(p->real_parent) == task_session(p)) 285 return 0; 286 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 287 288 return 1; 289 } 290 291 int is_current_pgrp_orphaned(void) 292 { 293 int retval; 294 295 read_lock(&tasklist_lock); 296 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); 297 read_unlock(&tasklist_lock); 298 299 return retval; 300 } 301 302 static bool has_stopped_jobs(struct pid *pgrp) 303 { 304 struct task_struct *p; 305 306 do_each_pid_task(pgrp, PIDTYPE_PGID, p) { 307 if (p->signal->flags & SIGNAL_STOP_STOPPED) 308 return true; 309 } while_each_pid_task(pgrp, PIDTYPE_PGID, p); 310 311 return false; 312 } 313 314 /* 315 * Check to see if any process groups have become orphaned as 316 * a result of our exiting, and if they have any stopped jobs, 317 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 318 */ 319 static void 320 kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) 321 { 322 struct pid *pgrp = task_pgrp(tsk); 323 struct task_struct *ignored_task = tsk; 324 325 if (!parent) 326 /* exit: our father is in a different pgrp than 327 * we are and we were the only connection outside. 328 */ 329 parent = tsk->real_parent; 330 else 331 /* reparent: our child is in a different pgrp than 332 * we are, and it was the only connection outside. 333 */ 334 ignored_task = NULL; 335 336 if (task_pgrp(parent) != pgrp && 337 task_session(parent) == task_session(tsk) && 338 will_become_orphaned_pgrp(pgrp, ignored_task) && 339 has_stopped_jobs(pgrp)) { 340 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); 341 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); 342 } 343 } 344 345 static void coredump_task_exit(struct task_struct *tsk) 346 { 347 struct core_state *core_state; 348 349 /* 350 * Serialize with any possible pending coredump. 351 * We must hold siglock around checking core_state 352 * and setting PF_POSTCOREDUMP. The core-inducing thread 353 * will increment ->nr_threads for each thread in the 354 * group without PF_POSTCOREDUMP set. 355 */ 356 spin_lock_irq(&tsk->sighand->siglock); 357 tsk->flags |= PF_POSTCOREDUMP; 358 core_state = tsk->signal->core_state; 359 spin_unlock_irq(&tsk->sighand->siglock); 360 if (core_state) { 361 struct core_thread self; 362 363 self.task = current; 364 if (self.task->flags & PF_SIGNALED) 365 self.next = xchg(&core_state->dumper.next, &self); 366 else 367 self.task = NULL; 368 /* 369 * Implies mb(), the result of xchg() must be visible 370 * to core_state->dumper. 371 */ 372 if (atomic_dec_and_test(&core_state->nr_threads)) 373 complete(&core_state->startup); 374 375 for (;;) { 376 set_current_state(TASK_UNINTERRUPTIBLE); 377 if (!self.task) /* see coredump_finish() */ 378 break; 379 freezable_schedule(); 380 } 381 __set_current_state(TASK_RUNNING); 382 } 383 } 384 385 #ifdef CONFIG_MEMCG 386 /* 387 * A task is exiting. If it owned this mm, find a new owner for the mm. 388 */ 389 void mm_update_next_owner(struct mm_struct *mm) 390 { 391 struct task_struct *c, *g, *p = current; 392 393 retry: 394 /* 395 * If the exiting or execing task is not the owner, it's 396 * someone else's problem. 397 */ 398 if (mm->owner != p) 399 return; 400 /* 401 * The current owner is exiting/execing and there are no other 402 * candidates. Do not leave the mm pointing to a possibly 403 * freed task structure. 404 */ 405 if (atomic_read(&mm->mm_users) <= 1) { 406 WRITE_ONCE(mm->owner, NULL); 407 return; 408 } 409 410 read_lock(&tasklist_lock); 411 /* 412 * Search in the children 413 */ 414 list_for_each_entry(c, &p->children, sibling) { 415 if (c->mm == mm) 416 goto assign_new_owner; 417 } 418 419 /* 420 * Search in the siblings 421 */ 422 list_for_each_entry(c, &p->real_parent->children, sibling) { 423 if (c->mm == mm) 424 goto assign_new_owner; 425 } 426 427 /* 428 * Search through everything else, we should not get here often. 429 */ 430 for_each_process(g) { 431 if (g->flags & PF_KTHREAD) 432 continue; 433 for_each_thread(g, c) { 434 if (c->mm == mm) 435 goto assign_new_owner; 436 if (c->mm) 437 break; 438 } 439 } 440 read_unlock(&tasklist_lock); 441 /* 442 * We found no owner yet mm_users > 1: this implies that we are 443 * most likely racing with swapoff (try_to_unuse()) or /proc or 444 * ptrace or page migration (get_task_mm()). Mark owner as NULL. 445 */ 446 WRITE_ONCE(mm->owner, NULL); 447 return; 448 449 assign_new_owner: 450 BUG_ON(c == p); 451 get_task_struct(c); 452 /* 453 * The task_lock protects c->mm from changing. 454 * We always want mm->owner->mm == mm 455 */ 456 task_lock(c); 457 /* 458 * Delay read_unlock() till we have the task_lock() 459 * to ensure that c does not slip away underneath us 460 */ 461 read_unlock(&tasklist_lock); 462 if (c->mm != mm) { 463 task_unlock(c); 464 put_task_struct(c); 465 goto retry; 466 } 467 WRITE_ONCE(mm->owner, c); 468 task_unlock(c); 469 put_task_struct(c); 470 } 471 #endif /* CONFIG_MEMCG */ 472 473 /* 474 * Turn us into a lazy TLB process if we 475 * aren't already.. 476 */ 477 static void exit_mm(void) 478 { 479 struct mm_struct *mm = current->mm; 480 481 exit_mm_release(current, mm); 482 if (!mm) 483 return; 484 sync_mm_rss(mm); 485 mmap_read_lock(mm); 486 mmgrab(mm); 487 BUG_ON(mm != current->active_mm); 488 /* more a memory barrier than a real lock */ 489 task_lock(current); 490 /* 491 * When a thread stops operating on an address space, the loop 492 * in membarrier_private_expedited() may not observe that 493 * tsk->mm, and the loop in membarrier_global_expedited() may 494 * not observe a MEMBARRIER_STATE_GLOBAL_EXPEDITED 495 * rq->membarrier_state, so those would not issue an IPI. 496 * Membarrier requires a memory barrier after accessing 497 * user-space memory, before clearing tsk->mm or the 498 * rq->membarrier_state. 499 */ 500 smp_mb__after_spinlock(); 501 local_irq_disable(); 502 current->mm = NULL; 503 membarrier_update_current_mm(NULL); 504 enter_lazy_tlb(mm, current); 505 local_irq_enable(); 506 task_unlock(current); 507 mmap_read_unlock(mm); 508 mm_update_next_owner(mm); 509 mmput(mm); 510 if (test_thread_flag(TIF_MEMDIE)) 511 exit_oom_victim(); 512 } 513 514 static struct task_struct *find_alive_thread(struct task_struct *p) 515 { 516 struct task_struct *t; 517 518 for_each_thread(p, t) { 519 if (!(t->flags & PF_EXITING)) 520 return t; 521 } 522 return NULL; 523 } 524 525 static struct task_struct *find_child_reaper(struct task_struct *father, 526 struct list_head *dead) 527 __releases(&tasklist_lock) 528 __acquires(&tasklist_lock) 529 { 530 struct pid_namespace *pid_ns = task_active_pid_ns(father); 531 struct task_struct *reaper = pid_ns->child_reaper; 532 struct task_struct *p, *n; 533 534 if (likely(reaper != father)) 535 return reaper; 536 537 reaper = find_alive_thread(father); 538 if (reaper) { 539 pid_ns->child_reaper = reaper; 540 return reaper; 541 } 542 543 write_unlock_irq(&tasklist_lock); 544 545 list_for_each_entry_safe(p, n, dead, ptrace_entry) { 546 list_del_init(&p->ptrace_entry); 547 release_task(p); 548 } 549 550 zap_pid_ns_processes(pid_ns); 551 write_lock_irq(&tasklist_lock); 552 553 return father; 554 } 555 556 /* 557 * When we die, we re-parent all our children, and try to: 558 * 1. give them to another thread in our thread group, if such a member exists 559 * 2. give it to the first ancestor process which prctl'd itself as a 560 * child_subreaper for its children (like a service manager) 561 * 3. give it to the init process (PID 1) in our pid namespace 562 */ 563 static struct task_struct *find_new_reaper(struct task_struct *father, 564 struct task_struct *child_reaper) 565 { 566 struct task_struct *thread, *reaper; 567 568 thread = find_alive_thread(father); 569 if (thread) 570 return thread; 571 572 if (father->signal->has_child_subreaper) { 573 unsigned int ns_level = task_pid(father)->level; 574 /* 575 * Find the first ->is_child_subreaper ancestor in our pid_ns. 576 * We can't check reaper != child_reaper to ensure we do not 577 * cross the namespaces, the exiting parent could be injected 578 * by setns() + fork(). 579 * We check pid->level, this is slightly more efficient than 580 * task_active_pid_ns(reaper) != task_active_pid_ns(father). 581 */ 582 for (reaper = father->real_parent; 583 task_pid(reaper)->level == ns_level; 584 reaper = reaper->real_parent) { 585 if (reaper == &init_task) 586 break; 587 if (!reaper->signal->is_child_subreaper) 588 continue; 589 thread = find_alive_thread(reaper); 590 if (thread) 591 return thread; 592 } 593 } 594 595 return child_reaper; 596 } 597 598 /* 599 * Any that need to be release_task'd are put on the @dead list. 600 */ 601 static void reparent_leader(struct task_struct *father, struct task_struct *p, 602 struct list_head *dead) 603 { 604 if (unlikely(p->exit_state == EXIT_DEAD)) 605 return; 606 607 /* We don't want people slaying init. */ 608 p->exit_signal = SIGCHLD; 609 610 /* If it has exited notify the new parent about this child's death. */ 611 if (!p->ptrace && 612 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { 613 if (do_notify_parent(p, p->exit_signal)) { 614 p->exit_state = EXIT_DEAD; 615 list_add(&p->ptrace_entry, dead); 616 } 617 } 618 619 kill_orphaned_pgrp(p, father); 620 } 621 622 /* 623 * This does two things: 624 * 625 * A. Make init inherit all the child processes 626 * B. Check to see if any process groups have become orphaned 627 * as a result of our exiting, and if they have any stopped 628 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) 629 */ 630 static void forget_original_parent(struct task_struct *father, 631 struct list_head *dead) 632 { 633 struct task_struct *p, *t, *reaper; 634 635 if (unlikely(!list_empty(&father->ptraced))) 636 exit_ptrace(father, dead); 637 638 /* Can drop and reacquire tasklist_lock */ 639 reaper = find_child_reaper(father, dead); 640 if (list_empty(&father->children)) 641 return; 642 643 reaper = find_new_reaper(father, reaper); 644 list_for_each_entry(p, &father->children, sibling) { 645 for_each_thread(p, t) { 646 RCU_INIT_POINTER(t->real_parent, reaper); 647 BUG_ON((!t->ptrace) != (rcu_access_pointer(t->parent) == father)); 648 if (likely(!t->ptrace)) 649 t->parent = t->real_parent; 650 if (t->pdeath_signal) 651 group_send_sig_info(t->pdeath_signal, 652 SEND_SIG_NOINFO, t, 653 PIDTYPE_TGID); 654 } 655 /* 656 * If this is a threaded reparent there is no need to 657 * notify anyone anything has happened. 658 */ 659 if (!same_thread_group(reaper, father)) 660 reparent_leader(father, p, dead); 661 } 662 list_splice_tail_init(&father->children, &reaper->children); 663 } 664 665 /* 666 * Send signals to all our closest relatives so that they know 667 * to properly mourn us.. 668 */ 669 static void exit_notify(struct task_struct *tsk, int group_dead) 670 { 671 bool autoreap; 672 struct task_struct *p, *n; 673 LIST_HEAD(dead); 674 675 write_lock_irq(&tasklist_lock); 676 forget_original_parent(tsk, &dead); 677 678 if (group_dead) 679 kill_orphaned_pgrp(tsk->group_leader, NULL); 680 681 tsk->exit_state = EXIT_ZOMBIE; 682 if (unlikely(tsk->ptrace)) { 683 int sig = thread_group_leader(tsk) && 684 thread_group_empty(tsk) && 685 !ptrace_reparented(tsk) ? 686 tsk->exit_signal : SIGCHLD; 687 autoreap = do_notify_parent(tsk, sig); 688 } else if (thread_group_leader(tsk)) { 689 autoreap = thread_group_empty(tsk) && 690 do_notify_parent(tsk, tsk->exit_signal); 691 } else { 692 autoreap = true; 693 } 694 695 if (autoreap) { 696 tsk->exit_state = EXIT_DEAD; 697 list_add(&tsk->ptrace_entry, &dead); 698 } 699 700 /* mt-exec, de_thread() is waiting for group leader */ 701 if (unlikely(tsk->signal->notify_count < 0)) 702 wake_up_process(tsk->signal->group_exec_task); 703 write_unlock_irq(&tasklist_lock); 704 705 list_for_each_entry_safe(p, n, &dead, ptrace_entry) { 706 list_del_init(&p->ptrace_entry); 707 release_task(p); 708 } 709 } 710 711 #ifdef CONFIG_DEBUG_STACK_USAGE 712 static void check_stack_usage(void) 713 { 714 static DEFINE_SPINLOCK(low_water_lock); 715 static int lowest_to_date = THREAD_SIZE; 716 unsigned long free; 717 718 free = stack_not_used(current); 719 720 if (free >= lowest_to_date) 721 return; 722 723 spin_lock(&low_water_lock); 724 if (free < lowest_to_date) { 725 pr_info("%s (%d) used greatest stack depth: %lu bytes left\n", 726 current->comm, task_pid_nr(current), free); 727 lowest_to_date = free; 728 } 729 spin_unlock(&low_water_lock); 730 } 731 #else 732 static inline void check_stack_usage(void) {} 733 #endif 734 735 void __noreturn do_exit(long code) 736 { 737 struct task_struct *tsk = current; 738 int group_dead; 739 740 WARN_ON(blk_needs_flush_plug(tsk)); 741 742 /* 743 * If do_dead is called because this processes oopsed, it's possible 744 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before 745 * continuing. Amongst other possible reasons, this is to prevent 746 * mm_release()->clear_child_tid() from writing to a user-controlled 747 * kernel address. 748 * 749 * On uptodate architectures force_uaccess_begin is a noop. On 750 * architectures that still have set_fs/get_fs in addition to handling 751 * oopses handles kernel threads that run as set_fs(KERNEL_DS) by 752 * default. 753 */ 754 force_uaccess_begin(); 755 756 kcov_task_exit(tsk); 757 758 coredump_task_exit(tsk); 759 ptrace_event(PTRACE_EVENT_EXIT, code); 760 761 validate_creds_for_do_exit(tsk); 762 763 io_uring_files_cancel(); 764 exit_signals(tsk); /* sets PF_EXITING */ 765 766 /* sync mm's RSS info before statistics gathering */ 767 if (tsk->mm) 768 sync_mm_rss(tsk->mm); 769 acct_update_integrals(tsk); 770 group_dead = atomic_dec_and_test(&tsk->signal->live); 771 if (group_dead) { 772 /* 773 * If the last thread of global init has exited, panic 774 * immediately to get a useable coredump. 775 */ 776 if (unlikely(is_global_init(tsk))) 777 panic("Attempted to kill init! exitcode=0x%08x\n", 778 tsk->signal->group_exit_code ?: (int)code); 779 780 #ifdef CONFIG_POSIX_TIMERS 781 hrtimer_cancel(&tsk->signal->real_timer); 782 exit_itimers(tsk->signal); 783 #endif 784 if (tsk->mm) 785 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); 786 } 787 acct_collect(code, group_dead); 788 if (group_dead) 789 tty_audit_exit(); 790 audit_free(tsk); 791 792 tsk->exit_code = code; 793 taskstats_exit(tsk, group_dead); 794 795 exit_mm(); 796 797 if (group_dead) 798 acct_process(); 799 trace_sched_process_exit(tsk); 800 801 exit_sem(tsk); 802 exit_shm(tsk); 803 exit_files(tsk); 804 exit_fs(tsk); 805 if (group_dead) 806 disassociate_ctty(1); 807 exit_task_namespaces(tsk); 808 exit_task_work(tsk); 809 exit_thread(tsk); 810 811 /* 812 * Flush inherited counters to the parent - before the parent 813 * gets woken up by child-exit notifications. 814 * 815 * because of cgroup mode, must be called before cgroup_exit() 816 */ 817 perf_event_exit_task(tsk); 818 819 sched_autogroup_exit_task(tsk); 820 cgroup_exit(tsk); 821 822 /* 823 * FIXME: do that only when needed, using sched_exit tracepoint 824 */ 825 flush_ptrace_hw_breakpoint(tsk); 826 827 exit_tasks_rcu_start(); 828 exit_notify(tsk, group_dead); 829 proc_exit_connector(tsk); 830 mpol_put_task_policy(tsk); 831 #ifdef CONFIG_FUTEX 832 if (unlikely(current->pi_state_cache)) 833 kfree(current->pi_state_cache); 834 #endif 835 /* 836 * Make sure we are holding no locks: 837 */ 838 debug_check_no_locks_held(); 839 840 if (tsk->io_context) 841 exit_io_context(tsk); 842 843 if (tsk->splice_pipe) 844 free_pipe_info(tsk->splice_pipe); 845 846 if (tsk->task_frag.page) 847 put_page(tsk->task_frag.page); 848 849 validate_creds_for_do_exit(tsk); 850 851 check_stack_usage(); 852 preempt_disable(); 853 if (tsk->nr_dirtied) 854 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); 855 exit_rcu(); 856 exit_tasks_rcu_finish(); 857 858 lockdep_free_task(tsk); 859 do_task_dead(); 860 } 861 862 void __noreturn make_task_dead(int signr) 863 { 864 /* 865 * Take the task off the cpu after something catastrophic has 866 * happened. 867 * 868 * We can get here from a kernel oops, sometimes with preemption off. 869 * Start by checking for critical errors. 870 * Then fix up important state like USER_DS and preemption. 871 * Then do everything else. 872 */ 873 struct task_struct *tsk = current; 874 875 if (unlikely(in_interrupt())) 876 panic("Aiee, killing interrupt handler!"); 877 if (unlikely(!tsk->pid)) 878 panic("Attempted to kill the idle task!"); 879 880 if (unlikely(in_atomic())) { 881 pr_info("note: %s[%d] exited with preempt_count %d\n", 882 current->comm, task_pid_nr(current), 883 preempt_count()); 884 preempt_count_set(PREEMPT_ENABLED); 885 } 886 887 /* 888 * We're taking recursive faults here in make_task_dead. Safest is to just 889 * leave this task alone and wait for reboot. 890 */ 891 if (unlikely(tsk->flags & PF_EXITING)) { 892 pr_alert("Fixing recursive fault but reboot is needed!\n"); 893 futex_exit_recursive(tsk); 894 tsk->exit_state = EXIT_DEAD; 895 refcount_inc(&tsk->rcu_users); 896 do_task_dead(); 897 } 898 899 do_exit(signr); 900 } 901 902 SYSCALL_DEFINE1(exit, int, error_code) 903 { 904 do_exit((error_code&0xff)<<8); 905 } 906 907 /* 908 * Take down every thread in the group. This is called by fatal signals 909 * as well as by sys_exit_group (below). 910 */ 911 void 912 do_group_exit(int exit_code) 913 { 914 struct signal_struct *sig = current->signal; 915 916 if (sig->flags & SIGNAL_GROUP_EXIT) 917 exit_code = sig->group_exit_code; 918 else if (sig->group_exec_task) 919 exit_code = 0; 920 else if (!thread_group_empty(current)) { 921 struct sighand_struct *const sighand = current->sighand; 922 923 spin_lock_irq(&sighand->siglock); 924 if (sig->flags & SIGNAL_GROUP_EXIT) 925 /* Another thread got here before we took the lock. */ 926 exit_code = sig->group_exit_code; 927 else if (sig->group_exec_task) 928 exit_code = 0; 929 else { 930 sig->group_exit_code = exit_code; 931 sig->flags = SIGNAL_GROUP_EXIT; 932 zap_other_threads(current); 933 } 934 spin_unlock_irq(&sighand->siglock); 935 } 936 937 do_exit(exit_code); 938 /* NOTREACHED */ 939 } 940 941 /* 942 * this kills every thread in the thread group. Note that any externally 943 * wait4()-ing process will get the correct exit code - even if this 944 * thread is not the thread group leader. 945 */ 946 SYSCALL_DEFINE1(exit_group, int, error_code) 947 { 948 do_group_exit((error_code & 0xff) << 8); 949 /* NOTREACHED */ 950 return 0; 951 } 952 953 struct waitid_info { 954 pid_t pid; 955 uid_t uid; 956 int status; 957 int cause; 958 }; 959 960 struct wait_opts { 961 enum pid_type wo_type; 962 int wo_flags; 963 struct pid *wo_pid; 964 965 struct waitid_info *wo_info; 966 int wo_stat; 967 struct rusage *wo_rusage; 968 969 wait_queue_entry_t child_wait; 970 int notask_error; 971 }; 972 973 static int eligible_pid(struct wait_opts *wo, struct task_struct *p) 974 { 975 return wo->wo_type == PIDTYPE_MAX || 976 task_pid_type(p, wo->wo_type) == wo->wo_pid; 977 } 978 979 static int 980 eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p) 981 { 982 if (!eligible_pid(wo, p)) 983 return 0; 984 985 /* 986 * Wait for all children (clone and not) if __WALL is set or 987 * if it is traced by us. 988 */ 989 if (ptrace || (wo->wo_flags & __WALL)) 990 return 1; 991 992 /* 993 * Otherwise, wait for clone children *only* if __WCLONE is set; 994 * otherwise, wait for non-clone children *only*. 995 * 996 * Note: a "clone" child here is one that reports to its parent 997 * using a signal other than SIGCHLD, or a non-leader thread which 998 * we can only see if it is traced by us. 999 */ 1000 if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) 1001 return 0; 1002 1003 return 1; 1004 } 1005 1006 /* 1007 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold 1008 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1009 * the lock and this task is uninteresting. If we return nonzero, we have 1010 * released the lock and the system call should return. 1011 */ 1012 static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) 1013 { 1014 int state, status; 1015 pid_t pid = task_pid_vnr(p); 1016 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1017 struct waitid_info *infop; 1018 1019 if (!likely(wo->wo_flags & WEXITED)) 1020 return 0; 1021 1022 if (unlikely(wo->wo_flags & WNOWAIT)) { 1023 status = (p->signal->flags & SIGNAL_GROUP_EXIT) 1024 ? p->signal->group_exit_code : p->exit_code; 1025 get_task_struct(p); 1026 read_unlock(&tasklist_lock); 1027 sched_annotate_sleep(); 1028 if (wo->wo_rusage) 1029 getrusage(p, RUSAGE_BOTH, wo->wo_rusage); 1030 put_task_struct(p); 1031 goto out_info; 1032 } 1033 /* 1034 * Move the task's state to DEAD/TRACE, only one thread can do this. 1035 */ 1036 state = (ptrace_reparented(p) && thread_group_leader(p)) ? 1037 EXIT_TRACE : EXIT_DEAD; 1038 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) 1039 return 0; 1040 /* 1041 * We own this thread, nobody else can reap it. 1042 */ 1043 read_unlock(&tasklist_lock); 1044 sched_annotate_sleep(); 1045 1046 /* 1047 * Check thread_group_leader() to exclude the traced sub-threads. 1048 */ 1049 if (state == EXIT_DEAD && thread_group_leader(p)) { 1050 struct signal_struct *sig = p->signal; 1051 struct signal_struct *psig = current->signal; 1052 unsigned long maxrss; 1053 u64 tgutime, tgstime; 1054 1055 /* 1056 * The resource counters for the group leader are in its 1057 * own task_struct. Those for dead threads in the group 1058 * are in its signal_struct, as are those for the child 1059 * processes it has previously reaped. All these 1060 * accumulate in the parent's signal_struct c* fields. 1061 * 1062 * We don't bother to take a lock here to protect these 1063 * p->signal fields because the whole thread group is dead 1064 * and nobody can change them. 1065 * 1066 * psig->stats_lock also protects us from our sub-theads 1067 * which can reap other children at the same time. Until 1068 * we change k_getrusage()-like users to rely on this lock 1069 * we have to take ->siglock as well. 1070 * 1071 * We use thread_group_cputime_adjusted() to get times for 1072 * the thread group, which consolidates times for all threads 1073 * in the group including the group leader. 1074 */ 1075 thread_group_cputime_adjusted(p, &tgutime, &tgstime); 1076 spin_lock_irq(¤t->sighand->siglock); 1077 write_seqlock(&psig->stats_lock); 1078 psig->cutime += tgutime + sig->cutime; 1079 psig->cstime += tgstime + sig->cstime; 1080 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime; 1081 psig->cmin_flt += 1082 p->min_flt + sig->min_flt + sig->cmin_flt; 1083 psig->cmaj_flt += 1084 p->maj_flt + sig->maj_flt + sig->cmaj_flt; 1085 psig->cnvcsw += 1086 p->nvcsw + sig->nvcsw + sig->cnvcsw; 1087 psig->cnivcsw += 1088 p->nivcsw + sig->nivcsw + sig->cnivcsw; 1089 psig->cinblock += 1090 task_io_get_inblock(p) + 1091 sig->inblock + sig->cinblock; 1092 psig->coublock += 1093 task_io_get_oublock(p) + 1094 sig->oublock + sig->coublock; 1095 maxrss = max(sig->maxrss, sig->cmaxrss); 1096 if (psig->cmaxrss < maxrss) 1097 psig->cmaxrss = maxrss; 1098 task_io_accounting_add(&psig->ioac, &p->ioac); 1099 task_io_accounting_add(&psig->ioac, &sig->ioac); 1100 write_sequnlock(&psig->stats_lock); 1101 spin_unlock_irq(¤t->sighand->siglock); 1102 } 1103 1104 if (wo->wo_rusage) 1105 getrusage(p, RUSAGE_BOTH, wo->wo_rusage); 1106 status = (p->signal->flags & SIGNAL_GROUP_EXIT) 1107 ? p->signal->group_exit_code : p->exit_code; 1108 wo->wo_stat = status; 1109 1110 if (state == EXIT_TRACE) { 1111 write_lock_irq(&tasklist_lock); 1112 /* We dropped tasklist, ptracer could die and untrace */ 1113 ptrace_unlink(p); 1114 1115 /* If parent wants a zombie, don't release it now */ 1116 state = EXIT_ZOMBIE; 1117 if (do_notify_parent(p, p->exit_signal)) 1118 state = EXIT_DEAD; 1119 p->exit_state = state; 1120 write_unlock_irq(&tasklist_lock); 1121 } 1122 if (state == EXIT_DEAD) 1123 release_task(p); 1124 1125 out_info: 1126 infop = wo->wo_info; 1127 if (infop) { 1128 if ((status & 0x7f) == 0) { 1129 infop->cause = CLD_EXITED; 1130 infop->status = status >> 8; 1131 } else { 1132 infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; 1133 infop->status = status & 0x7f; 1134 } 1135 infop->pid = pid; 1136 infop->uid = uid; 1137 } 1138 1139 return pid; 1140 } 1141 1142 static int *task_stopped_code(struct task_struct *p, bool ptrace) 1143 { 1144 if (ptrace) { 1145 if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING)) 1146 return &p->exit_code; 1147 } else { 1148 if (p->signal->flags & SIGNAL_STOP_STOPPED) 1149 return &p->signal->group_exit_code; 1150 } 1151 return NULL; 1152 } 1153 1154 /** 1155 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED 1156 * @wo: wait options 1157 * @ptrace: is the wait for ptrace 1158 * @p: task to wait for 1159 * 1160 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED. 1161 * 1162 * CONTEXT: 1163 * read_lock(&tasklist_lock), which is released if return value is 1164 * non-zero. Also, grabs and releases @p->sighand->siglock. 1165 * 1166 * RETURNS: 1167 * 0 if wait condition didn't exist and search for other wait conditions 1168 * should continue. Non-zero return, -errno on failure and @p's pid on 1169 * success, implies that tasklist_lock is released and wait condition 1170 * search should terminate. 1171 */ 1172 static int wait_task_stopped(struct wait_opts *wo, 1173 int ptrace, struct task_struct *p) 1174 { 1175 struct waitid_info *infop; 1176 int exit_code, *p_code, why; 1177 uid_t uid = 0; /* unneeded, required by compiler */ 1178 pid_t pid; 1179 1180 /* 1181 * Traditionally we see ptrace'd stopped tasks regardless of options. 1182 */ 1183 if (!ptrace && !(wo->wo_flags & WUNTRACED)) 1184 return 0; 1185 1186 if (!task_stopped_code(p, ptrace)) 1187 return 0; 1188 1189 exit_code = 0; 1190 spin_lock_irq(&p->sighand->siglock); 1191 1192 p_code = task_stopped_code(p, ptrace); 1193 if (unlikely(!p_code)) 1194 goto unlock_sig; 1195 1196 exit_code = *p_code; 1197 if (!exit_code) 1198 goto unlock_sig; 1199 1200 if (!unlikely(wo->wo_flags & WNOWAIT)) 1201 *p_code = 0; 1202 1203 uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1204 unlock_sig: 1205 spin_unlock_irq(&p->sighand->siglock); 1206 if (!exit_code) 1207 return 0; 1208 1209 /* 1210 * Now we are pretty sure this task is interesting. 1211 * Make sure it doesn't get reaped out from under us while we 1212 * give up the lock and then examine it below. We don't want to 1213 * keep holding onto the tasklist_lock while we call getrusage and 1214 * possibly take page faults for user memory. 1215 */ 1216 get_task_struct(p); 1217 pid = task_pid_vnr(p); 1218 why = ptrace ? CLD_TRAPPED : CLD_STOPPED; 1219 read_unlock(&tasklist_lock); 1220 sched_annotate_sleep(); 1221 if (wo->wo_rusage) 1222 getrusage(p, RUSAGE_BOTH, wo->wo_rusage); 1223 put_task_struct(p); 1224 1225 if (likely(!(wo->wo_flags & WNOWAIT))) 1226 wo->wo_stat = (exit_code << 8) | 0x7f; 1227 1228 infop = wo->wo_info; 1229 if (infop) { 1230 infop->cause = why; 1231 infop->status = exit_code; 1232 infop->pid = pid; 1233 infop->uid = uid; 1234 } 1235 return pid; 1236 } 1237 1238 /* 1239 * Handle do_wait work for one task in a live, non-stopped state. 1240 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold 1241 * the lock and this task is uninteresting. If we return nonzero, we have 1242 * released the lock and the system call should return. 1243 */ 1244 static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) 1245 { 1246 struct waitid_info *infop; 1247 pid_t pid; 1248 uid_t uid; 1249 1250 if (!unlikely(wo->wo_flags & WCONTINUED)) 1251 return 0; 1252 1253 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) 1254 return 0; 1255 1256 spin_lock_irq(&p->sighand->siglock); 1257 /* Re-check with the lock held. */ 1258 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { 1259 spin_unlock_irq(&p->sighand->siglock); 1260 return 0; 1261 } 1262 if (!unlikely(wo->wo_flags & WNOWAIT)) 1263 p->signal->flags &= ~SIGNAL_STOP_CONTINUED; 1264 uid = from_kuid_munged(current_user_ns(), task_uid(p)); 1265 spin_unlock_irq(&p->sighand->siglock); 1266 1267 pid = task_pid_vnr(p); 1268 get_task_struct(p); 1269 read_unlock(&tasklist_lock); 1270 sched_annotate_sleep(); 1271 if (wo->wo_rusage) 1272 getrusage(p, RUSAGE_BOTH, wo->wo_rusage); 1273 put_task_struct(p); 1274 1275 infop = wo->wo_info; 1276 if (!infop) { 1277 wo->wo_stat = 0xffff; 1278 } else { 1279 infop->cause = CLD_CONTINUED; 1280 infop->pid = pid; 1281 infop->uid = uid; 1282 infop->status = SIGCONT; 1283 } 1284 return pid; 1285 } 1286 1287 /* 1288 * Consider @p for a wait by @parent. 1289 * 1290 * -ECHILD should be in ->notask_error before the first call. 1291 * Returns nonzero for a final return, when we have unlocked tasklist_lock. 1292 * Returns zero if the search for a child should continue; 1293 * then ->notask_error is 0 if @p is an eligible child, 1294 * or still -ECHILD. 1295 */ 1296 static int wait_consider_task(struct wait_opts *wo, int ptrace, 1297 struct task_struct *p) 1298 { 1299 /* 1300 * We can race with wait_task_zombie() from another thread. 1301 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition 1302 * can't confuse the checks below. 1303 */ 1304 int exit_state = READ_ONCE(p->exit_state); 1305 int ret; 1306 1307 if (unlikely(exit_state == EXIT_DEAD)) 1308 return 0; 1309 1310 ret = eligible_child(wo, ptrace, p); 1311 if (!ret) 1312 return ret; 1313 1314 if (unlikely(exit_state == EXIT_TRACE)) { 1315 /* 1316 * ptrace == 0 means we are the natural parent. In this case 1317 * we should clear notask_error, debugger will notify us. 1318 */ 1319 if (likely(!ptrace)) 1320 wo->notask_error = 0; 1321 return 0; 1322 } 1323 1324 if (likely(!ptrace) && unlikely(p->ptrace)) { 1325 /* 1326 * If it is traced by its real parent's group, just pretend 1327 * the caller is ptrace_do_wait() and reap this child if it 1328 * is zombie. 1329 * 1330 * This also hides group stop state from real parent; otherwise 1331 * a single stop can be reported twice as group and ptrace stop. 1332 * If a ptracer wants to distinguish these two events for its 1333 * own children it should create a separate process which takes 1334 * the role of real parent. 1335 */ 1336 if (!ptrace_reparented(p)) 1337 ptrace = 1; 1338 } 1339 1340 /* slay zombie? */ 1341 if (exit_state == EXIT_ZOMBIE) { 1342 /* we don't reap group leaders with subthreads */ 1343 if (!delay_group_leader(p)) { 1344 /* 1345 * A zombie ptracee is only visible to its ptracer. 1346 * Notification and reaping will be cascaded to the 1347 * real parent when the ptracer detaches. 1348 */ 1349 if (unlikely(ptrace) || likely(!p->ptrace)) 1350 return wait_task_zombie(wo, p); 1351 } 1352 1353 /* 1354 * Allow access to stopped/continued state via zombie by 1355 * falling through. Clearing of notask_error is complex. 1356 * 1357 * When !@ptrace: 1358 * 1359 * If WEXITED is set, notask_error should naturally be 1360 * cleared. If not, subset of WSTOPPED|WCONTINUED is set, 1361 * so, if there are live subthreads, there are events to 1362 * wait for. If all subthreads are dead, it's still safe 1363 * to clear - this function will be called again in finite 1364 * amount time once all the subthreads are released and 1365 * will then return without clearing. 1366 * 1367 * When @ptrace: 1368 * 1369 * Stopped state is per-task and thus can't change once the 1370 * target task dies. Only continued and exited can happen. 1371 * Clear notask_error if WCONTINUED | WEXITED. 1372 */ 1373 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED))) 1374 wo->notask_error = 0; 1375 } else { 1376 /* 1377 * @p is alive and it's gonna stop, continue or exit, so 1378 * there always is something to wait for. 1379 */ 1380 wo->notask_error = 0; 1381 } 1382 1383 /* 1384 * Wait for stopped. Depending on @ptrace, different stopped state 1385 * is used and the two don't interact with each other. 1386 */ 1387 ret = wait_task_stopped(wo, ptrace, p); 1388 if (ret) 1389 return ret; 1390 1391 /* 1392 * Wait for continued. There's only one continued state and the 1393 * ptracer can consume it which can confuse the real parent. Don't 1394 * use WCONTINUED from ptracer. You don't need or want it. 1395 */ 1396 return wait_task_continued(wo, p); 1397 } 1398 1399 /* 1400 * Do the work of do_wait() for one thread in the group, @tsk. 1401 * 1402 * -ECHILD should be in ->notask_error before the first call. 1403 * Returns nonzero for a final return, when we have unlocked tasklist_lock. 1404 * Returns zero if the search for a child should continue; then 1405 * ->notask_error is 0 if there were any eligible children, 1406 * or still -ECHILD. 1407 */ 1408 static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) 1409 { 1410 struct task_struct *p; 1411 1412 list_for_each_entry(p, &tsk->children, sibling) { 1413 int ret = wait_consider_task(wo, 0, p); 1414 1415 if (ret) 1416 return ret; 1417 } 1418 1419 return 0; 1420 } 1421 1422 static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) 1423 { 1424 struct task_struct *p; 1425 1426 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { 1427 int ret = wait_consider_task(wo, 1, p); 1428 1429 if (ret) 1430 return ret; 1431 } 1432 1433 return 0; 1434 } 1435 1436 static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode, 1437 int sync, void *key) 1438 { 1439 struct wait_opts *wo = container_of(wait, struct wait_opts, 1440 child_wait); 1441 struct task_struct *p = key; 1442 1443 if (!eligible_pid(wo, p)) 1444 return 0; 1445 1446 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) 1447 return 0; 1448 1449 return default_wake_function(wait, mode, sync, key); 1450 } 1451 1452 void __wake_up_parent(struct task_struct *p, struct task_struct *parent) 1453 { 1454 __wake_up_sync_key(&parent->signal->wait_chldexit, 1455 TASK_INTERRUPTIBLE, p); 1456 } 1457 1458 static bool is_effectively_child(struct wait_opts *wo, bool ptrace, 1459 struct task_struct *target) 1460 { 1461 struct task_struct *parent = 1462 !ptrace ? target->real_parent : target->parent; 1463 1464 return current == parent || (!(wo->wo_flags & __WNOTHREAD) && 1465 same_thread_group(current, parent)); 1466 } 1467 1468 /* 1469 * Optimization for waiting on PIDTYPE_PID. No need to iterate through child 1470 * and tracee lists to find the target task. 1471 */ 1472 static int do_wait_pid(struct wait_opts *wo) 1473 { 1474 bool ptrace; 1475 struct task_struct *target; 1476 int retval; 1477 1478 ptrace = false; 1479 target = pid_task(wo->wo_pid, PIDTYPE_TGID); 1480 if (target && is_effectively_child(wo, ptrace, target)) { 1481 retval = wait_consider_task(wo, ptrace, target); 1482 if (retval) 1483 return retval; 1484 } 1485 1486 ptrace = true; 1487 target = pid_task(wo->wo_pid, PIDTYPE_PID); 1488 if (target && target->ptrace && 1489 is_effectively_child(wo, ptrace, target)) { 1490 retval = wait_consider_task(wo, ptrace, target); 1491 if (retval) 1492 return retval; 1493 } 1494 1495 return 0; 1496 } 1497 1498 static long do_wait(struct wait_opts *wo) 1499 { 1500 int retval; 1501 1502 trace_sched_process_wait(wo->wo_pid); 1503 1504 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); 1505 wo->child_wait.private = current; 1506 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); 1507 repeat: 1508 /* 1509 * If there is nothing that can match our criteria, just get out. 1510 * We will clear ->notask_error to zero if we see any child that 1511 * might later match our criteria, even if we are not able to reap 1512 * it yet. 1513 */ 1514 wo->notask_error = -ECHILD; 1515 if ((wo->wo_type < PIDTYPE_MAX) && 1516 (!wo->wo_pid || !pid_has_task(wo->wo_pid, wo->wo_type))) 1517 goto notask; 1518 1519 set_current_state(TASK_INTERRUPTIBLE); 1520 read_lock(&tasklist_lock); 1521 1522 if (wo->wo_type == PIDTYPE_PID) { 1523 retval = do_wait_pid(wo); 1524 if (retval) 1525 goto end; 1526 } else { 1527 struct task_struct *tsk = current; 1528 1529 do { 1530 retval = do_wait_thread(wo, tsk); 1531 if (retval) 1532 goto end; 1533 1534 retval = ptrace_do_wait(wo, tsk); 1535 if (retval) 1536 goto end; 1537 1538 if (wo->wo_flags & __WNOTHREAD) 1539 break; 1540 } while_each_thread(current, tsk); 1541 } 1542 read_unlock(&tasklist_lock); 1543 1544 notask: 1545 retval = wo->notask_error; 1546 if (!retval && !(wo->wo_flags & WNOHANG)) { 1547 retval = -ERESTARTSYS; 1548 if (!signal_pending(current)) { 1549 schedule(); 1550 goto repeat; 1551 } 1552 } 1553 end: 1554 __set_current_state(TASK_RUNNING); 1555 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); 1556 return retval; 1557 } 1558 1559 static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, 1560 int options, struct rusage *ru) 1561 { 1562 struct wait_opts wo; 1563 struct pid *pid = NULL; 1564 enum pid_type type; 1565 long ret; 1566 unsigned int f_flags = 0; 1567 1568 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED| 1569 __WNOTHREAD|__WCLONE|__WALL)) 1570 return -EINVAL; 1571 if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) 1572 return -EINVAL; 1573 1574 switch (which) { 1575 case P_ALL: 1576 type = PIDTYPE_MAX; 1577 break; 1578 case P_PID: 1579 type = PIDTYPE_PID; 1580 if (upid <= 0) 1581 return -EINVAL; 1582 1583 pid = find_get_pid(upid); 1584 break; 1585 case P_PGID: 1586 type = PIDTYPE_PGID; 1587 if (upid < 0) 1588 return -EINVAL; 1589 1590 if (upid) 1591 pid = find_get_pid(upid); 1592 else 1593 pid = get_task_pid(current, PIDTYPE_PGID); 1594 break; 1595 case P_PIDFD: 1596 type = PIDTYPE_PID; 1597 if (upid < 0) 1598 return -EINVAL; 1599 1600 pid = pidfd_get_pid(upid, &f_flags); 1601 if (IS_ERR(pid)) 1602 return PTR_ERR(pid); 1603 1604 break; 1605 default: 1606 return -EINVAL; 1607 } 1608 1609 wo.wo_type = type; 1610 wo.wo_pid = pid; 1611 wo.wo_flags = options; 1612 wo.wo_info = infop; 1613 wo.wo_rusage = ru; 1614 if (f_flags & O_NONBLOCK) 1615 wo.wo_flags |= WNOHANG; 1616 1617 ret = do_wait(&wo); 1618 if (!ret && !(options & WNOHANG) && (f_flags & O_NONBLOCK)) 1619 ret = -EAGAIN; 1620 1621 put_pid(pid); 1622 return ret; 1623 } 1624 1625 SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, 1626 infop, int, options, struct rusage __user *, ru) 1627 { 1628 struct rusage r; 1629 struct waitid_info info = {.status = 0}; 1630 long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL); 1631 int signo = 0; 1632 1633 if (err > 0) { 1634 signo = SIGCHLD; 1635 err = 0; 1636 if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) 1637 return -EFAULT; 1638 } 1639 if (!infop) 1640 return err; 1641 1642 if (!user_write_access_begin(infop, sizeof(*infop))) 1643 return -EFAULT; 1644 1645 unsafe_put_user(signo, &infop->si_signo, Efault); 1646 unsafe_put_user(0, &infop->si_errno, Efault); 1647 unsafe_put_user(info.cause, &infop->si_code, Efault); 1648 unsafe_put_user(info.pid, &infop->si_pid, Efault); 1649 unsafe_put_user(info.uid, &infop->si_uid, Efault); 1650 unsafe_put_user(info.status, &infop->si_status, Efault); 1651 user_write_access_end(); 1652 return err; 1653 Efault: 1654 user_write_access_end(); 1655 return -EFAULT; 1656 } 1657 1658 long kernel_wait4(pid_t upid, int __user *stat_addr, int options, 1659 struct rusage *ru) 1660 { 1661 struct wait_opts wo; 1662 struct pid *pid = NULL; 1663 enum pid_type type; 1664 long ret; 1665 1666 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| 1667 __WNOTHREAD|__WCLONE|__WALL)) 1668 return -EINVAL; 1669 1670 /* -INT_MIN is not defined */ 1671 if (upid == INT_MIN) 1672 return -ESRCH; 1673 1674 if (upid == -1) 1675 type = PIDTYPE_MAX; 1676 else if (upid < 0) { 1677 type = PIDTYPE_PGID; 1678 pid = find_get_pid(-upid); 1679 } else if (upid == 0) { 1680 type = PIDTYPE_PGID; 1681 pid = get_task_pid(current, PIDTYPE_PGID); 1682 } else /* upid > 0 */ { 1683 type = PIDTYPE_PID; 1684 pid = find_get_pid(upid); 1685 } 1686 1687 wo.wo_type = type; 1688 wo.wo_pid = pid; 1689 wo.wo_flags = options | WEXITED; 1690 wo.wo_info = NULL; 1691 wo.wo_stat = 0; 1692 wo.wo_rusage = ru; 1693 ret = do_wait(&wo); 1694 put_pid(pid); 1695 if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr)) 1696 ret = -EFAULT; 1697 1698 return ret; 1699 } 1700 1701 int kernel_wait(pid_t pid, int *stat) 1702 { 1703 struct wait_opts wo = { 1704 .wo_type = PIDTYPE_PID, 1705 .wo_pid = find_get_pid(pid), 1706 .wo_flags = WEXITED, 1707 }; 1708 int ret; 1709 1710 ret = do_wait(&wo); 1711 if (ret > 0 && wo.wo_stat) 1712 *stat = wo.wo_stat; 1713 put_pid(wo.wo_pid); 1714 return ret; 1715 } 1716 1717 SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, 1718 int, options, struct rusage __user *, ru) 1719 { 1720 struct rusage r; 1721 long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL); 1722 1723 if (err > 0) { 1724 if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) 1725 return -EFAULT; 1726 } 1727 return err; 1728 } 1729 1730 #ifdef __ARCH_WANT_SYS_WAITPID 1731 1732 /* 1733 * sys_waitpid() remains for compatibility. waitpid() should be 1734 * implemented by calling sys_wait4() from libc.a. 1735 */ 1736 SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) 1737 { 1738 return kernel_wait4(pid, stat_addr, options, NULL); 1739 } 1740 1741 #endif 1742 1743 #ifdef CONFIG_COMPAT 1744 COMPAT_SYSCALL_DEFINE4(wait4, 1745 compat_pid_t, pid, 1746 compat_uint_t __user *, stat_addr, 1747 int, options, 1748 struct compat_rusage __user *, ru) 1749 { 1750 struct rusage r; 1751 long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL); 1752 if (err > 0) { 1753 if (ru && put_compat_rusage(&r, ru)) 1754 return -EFAULT; 1755 } 1756 return err; 1757 } 1758 1759 COMPAT_SYSCALL_DEFINE5(waitid, 1760 int, which, compat_pid_t, pid, 1761 struct compat_siginfo __user *, infop, int, options, 1762 struct compat_rusage __user *, uru) 1763 { 1764 struct rusage ru; 1765 struct waitid_info info = {.status = 0}; 1766 long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL); 1767 int signo = 0; 1768 if (err > 0) { 1769 signo = SIGCHLD; 1770 err = 0; 1771 if (uru) { 1772 /* kernel_waitid() overwrites everything in ru */ 1773 if (COMPAT_USE_64BIT_TIME) 1774 err = copy_to_user(uru, &ru, sizeof(ru)); 1775 else 1776 err = put_compat_rusage(&ru, uru); 1777 if (err) 1778 return -EFAULT; 1779 } 1780 } 1781 1782 if (!infop) 1783 return err; 1784 1785 if (!user_write_access_begin(infop, sizeof(*infop))) 1786 return -EFAULT; 1787 1788 unsafe_put_user(signo, &infop->si_signo, Efault); 1789 unsafe_put_user(0, &infop->si_errno, Efault); 1790 unsafe_put_user(info.cause, &infop->si_code, Efault); 1791 unsafe_put_user(info.pid, &infop->si_pid, Efault); 1792 unsafe_put_user(info.uid, &infop->si_uid, Efault); 1793 unsafe_put_user(info.status, &infop->si_status, Efault); 1794 user_write_access_end(); 1795 return err; 1796 Efault: 1797 user_write_access_end(); 1798 return -EFAULT; 1799 } 1800 #endif 1801 1802 /** 1803 * thread_group_exited - check that a thread group has exited 1804 * @pid: tgid of thread group to be checked. 1805 * 1806 * Test if the thread group represented by tgid has exited (all 1807 * threads are zombies, dead or completely gone). 1808 * 1809 * Return: true if the thread group has exited. false otherwise. 1810 */ 1811 bool thread_group_exited(struct pid *pid) 1812 { 1813 struct task_struct *task; 1814 bool exited; 1815 1816 rcu_read_lock(); 1817 task = pid_task(pid, PIDTYPE_PID); 1818 exited = !task || 1819 (READ_ONCE(task->exit_state) && thread_group_empty(task)); 1820 rcu_read_unlock(); 1821 1822 return exited; 1823 } 1824 EXPORT_SYMBOL(thread_group_exited); 1825 1826 __weak void abort(void) 1827 { 1828 BUG(); 1829 1830 /* if that doesn't kill us, halt */ 1831 panic("Oops failed to kill thread"); 1832 } 1833 EXPORT_SYMBOL(abort); 1834