Line data Source code
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 93 : static void __unhash_process(struct task_struct *p, bool group_dead)
75 : {
76 93 : nr_threads--;
77 93 : detach_pid(p, PIDTYPE_PID);
78 93 : if (group_dead) {
79 93 : detach_pid(p, PIDTYPE_TGID);
80 93 : detach_pid(p, PIDTYPE_PGID);
81 93 : detach_pid(p, PIDTYPE_SID);
82 :
83 186 : list_del_rcu(&p->tasks);
84 186 : list_del_init(&p->sibling);
85 93 : __this_cpu_dec(process_counts);
86 : }
87 186 : list_del_rcu(&p->thread_group);
88 186 : list_del_rcu(&p->thread_node);
89 93 : }
90 :
91 : /*
92 : * This function expects the tasklist_lock write-locked.
93 : */
94 93 : static void __exit_signal(struct task_struct *tsk)
95 : {
96 93 : struct signal_struct *sig = tsk->signal;
97 186 : bool group_dead = thread_group_leader(tsk);
98 : struct sighand_struct *sighand;
99 : struct tty_struct *tty;
100 : u64 utime, stime;
101 :
102 93 : sighand = rcu_dereference_check(tsk->sighand,
103 : lockdep_tasklist_lock_is_held());
104 186 : spin_lock(&sighand->siglock);
105 :
106 : #ifdef CONFIG_POSIX_TIMERS
107 93 : posix_cpu_timers_exit(tsk);
108 93 : if (group_dead)
109 93 : posix_cpu_timers_exit_group(tsk);
110 : #endif
111 :
112 93 : if (group_dead) {
113 93 : tty = sig->tty;
114 93 : sig->tty = NULL;
115 : } else {
116 : /*
117 : * If there is any task waiting for the group exit
118 : * then notify it:
119 : */
120 0 : if (sig->notify_count > 0 && !--sig->notify_count)
121 0 : wake_up_process(sig->group_exec_task);
122 :
123 0 : if (tsk == sig->curr_target)
124 0 : sig->curr_target = next_thread(tsk);
125 : }
126 :
127 93 : 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 : */
136 186 : task_cputime(tsk, &utime, &stime);
137 186 : write_seqlock(&sig->stats_lock);
138 93 : sig->utime += utime;
139 93 : sig->stime += stime;
140 93 : sig->gtime += task_gtime(tsk);
141 93 : sig->min_flt += tsk->min_flt;
142 93 : sig->maj_flt += tsk->maj_flt;
143 93 : sig->nvcsw += tsk->nvcsw;
144 93 : sig->nivcsw += tsk->nivcsw;
145 93 : sig->inblock += task_io_get_inblock(tsk);
146 93 : sig->oublock += task_io_get_oublock(tsk);
147 93 : task_io_accounting_add(&sig->ioac, &tsk->ioac);
148 93 : sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
149 93 : sig->nr_threads--;
150 93 : __unhash_process(tsk, group_dead);
151 186 : 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 93 : flush_sigqueue(&tsk->pending);
158 93 : tsk->sighand = NULL;
159 186 : spin_unlock(&sighand->siglock);
160 :
161 93 : __cleanup_sighand(sighand);
162 186 : clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
163 93 : if (group_dead) {
164 93 : flush_sigqueue(&sig->shared_pending);
165 93 : tty_kref_put(tty);
166 : }
167 93 : }
168 :
169 92 : static void delayed_put_task_struct(struct rcu_head *rhp)
170 : {
171 92 : struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
172 :
173 92 : kprobe_flush_task(tsk);
174 : rethook_flush_task(tsk);
175 92 : perf_event_delayed_put(tsk);
176 92 : trace_sched_process_free(tsk);
177 92 : put_task_struct(tsk);
178 92 : }
179 :
180 186 : void put_task_struct_rcu_user(struct task_struct *task)
181 : {
182 372 : if (refcount_dec_and_test(&task->rcu_users))
183 93 : call_rcu(&task->rcu, delayed_put_task_struct);
184 186 : }
185 :
186 93 : 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();
195 186 : dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
196 : rcu_read_unlock();
197 :
198 93 : cgroup_release(p);
199 :
200 93 : write_lock_irq(&tasklist_lock);
201 93 : ptrace_release_task(p);
202 186 : thread_pid = get_pid(p->thread_pid);
203 93 : __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 93 : zap_leader = 0;
211 93 : leader = p->group_leader;
212 93 : if (leader != p && thread_group_empty(leader)
213 0 : && 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 0 : zap_leader = do_notify_parent(leader, leader->exit_signal);
220 0 : if (zap_leader)
221 0 : leader->exit_state = EXIT_DEAD;
222 : }
223 :
224 93 : write_unlock_irq(&tasklist_lock);
225 93 : seccomp_filter_release(p);
226 93 : proc_flush_pid(thread_pid);
227 93 : put_pid(thread_pid);
228 93 : release_thread(p);
229 93 : put_task_struct_rcu_user(p);
230 :
231 93 : p = leader;
232 93 : if (unlikely(zap_leader))
233 : goto repeat;
234 93 : }
235 :
236 3 : int rcuwait_wake_up(struct rcuwait *w)
237 : {
238 3 : 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 3 : smp_mb(); /* (B) */
255 :
256 3 : task = rcu_dereference(w->task);
257 3 : if (task)
258 0 : ret = wake_up_process(task);
259 : rcu_read_unlock();
260 :
261 3 : 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 0 : static int will_become_orphaned_pgrp(struct pid *pgrp,
274 : struct task_struct *ignored_task)
275 : {
276 : struct task_struct *p;
277 :
278 0 : do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
279 0 : if ((p == ignored_task) ||
280 0 : (p->exit_state && thread_group_empty(p)) ||
281 0 : is_global_init(p->real_parent))
282 0 : continue;
283 :
284 0 : if (task_pgrp(p->real_parent) != pgrp &&
285 0 : 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 0 : int is_current_pgrp_orphaned(void)
293 : {
294 : int retval;
295 :
296 0 : read_lock(&tasklist_lock);
297 0 : retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
298 0 : read_unlock(&tasklist_lock);
299 :
300 0 : return retval;
301 : }
302 :
303 : static bool has_stopped_jobs(struct pid *pgrp)
304 : {
305 : struct task_struct *p;
306 :
307 0 : do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
308 0 : 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 93 : kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
322 : {
323 186 : struct pid *pgrp = task_pgrp(tsk);
324 93 : struct task_struct *ignored_task = tsk;
325 :
326 93 : if (!parent)
327 : /* exit: our father is in a different pgrp than
328 : * we are and we were the only connection outside.
329 : */
330 93 : 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 :
337 186 : if (task_pgrp(parent) != pgrp &&
338 0 : task_session(parent) == task_session(tsk) &&
339 0 : will_become_orphaned_pgrp(pgrp, ignored_task) &&
340 0 : has_stopped_jobs(pgrp)) {
341 0 : __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
342 0 : __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
343 : }
344 93 : }
345 :
346 93 : 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 : */
357 186 : spin_lock_irq(&tsk->sighand->siglock);
358 93 : tsk->flags |= PF_POSTCOREDUMP;
359 93 : core_state = tsk->signal->core_state;
360 186 : spin_unlock_irq(&tsk->sighand->siglock);
361 93 : if (core_state) {
362 : struct core_thread self;
363 :
364 0 : self.task = current;
365 0 : if (self.task->flags & PF_SIGNALED)
366 0 : self.next = xchg(&core_state->dumper.next, &self);
367 : else
368 0 : self.task = NULL;
369 : /*
370 : * Implies mb(), the result of xchg() must be visible
371 : * to core_state->dumper.
372 : */
373 0 : if (atomic_dec_and_test(&core_state->nr_threads))
374 0 : complete(&core_state->startup);
375 :
376 : for (;;) {
377 0 : set_current_state(TASK_UNINTERRUPTIBLE);
378 0 : if (!self.task) /* see coredump_finish() */
379 : break;
380 0 : freezable_schedule();
381 : }
382 0 : __set_current_state(TASK_RUNNING);
383 : }
384 93 : }
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 93 : static void exit_mm(void)
479 : {
480 93 : struct mm_struct *mm = current->mm;
481 :
482 93 : exit_mm_release(current, mm);
483 93 : if (!mm)
484 : return;
485 0 : sync_mm_rss(mm);
486 0 : mmap_read_lock(mm);
487 0 : mmgrab(mm);
488 0 : BUG_ON(mm != current->active_mm);
489 : /* more a memory barrier than a real lock */
490 0 : 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 0 : current->mm = NULL;
504 0 : membarrier_update_current_mm(NULL);
505 0 : enter_lazy_tlb(mm, current);
506 : local_irq_enable();
507 0 : task_unlock(current);
508 0 : mmap_read_unlock(mm);
509 0 : mm_update_next_owner(mm);
510 0 : mmput(mm);
511 0 : if (test_thread_flag(TIF_MEMDIE))
512 0 : 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 0 : for_each_thread(p, t) {
520 0 : if (!(t->flags & PF_EXITING))
521 : return t;
522 : }
523 : return NULL;
524 : }
525 :
526 93 : 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 93 : struct pid_namespace *pid_ns = task_active_pid_ns(father);
532 93 : struct task_struct *reaper = pid_ns->child_reaper;
533 : struct task_struct *p, *n;
534 :
535 93 : if (likely(reaper != father))
536 : return reaper;
537 :
538 0 : reaper = find_alive_thread(father);
539 0 : if (reaper) {
540 0 : pid_ns->child_reaper = reaper;
541 0 : return reaper;
542 : }
543 :
544 0 : write_unlock_irq(&tasklist_lock);
545 :
546 0 : list_for_each_entry_safe(p, n, dead, ptrace_entry) {
547 0 : list_del_init(&p->ptrace_entry);
548 0 : release_task(p);
549 : }
550 :
551 0 : zap_pid_ns_processes(pid_ns);
552 0 : write_lock_irq(&tasklist_lock);
553 :
554 0 : 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 0 : 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 0 : thread = find_alive_thread(father);
570 0 : if (thread)
571 : return thread;
572 :
573 0 : if (father->signal->has_child_subreaper) {
574 0 : 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 0 : for (reaper = father->real_parent;
584 0 : task_pid(reaper)->level == ns_level;
585 0 : reaper = reaper->real_parent) {
586 0 : if (reaper == &init_task)
587 : break;
588 0 : if (!reaper->signal->is_child_subreaper)
589 0 : continue;
590 0 : thread = find_alive_thread(reaper);
591 0 : 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 0 : static void reparent_leader(struct task_struct *father, struct task_struct *p,
603 : struct list_head *dead)
604 : {
605 0 : if (unlikely(p->exit_state == EXIT_DEAD))
606 : return;
607 :
608 : /* We don't want people slaying init. */
609 0 : p->exit_signal = SIGCHLD;
610 :
611 : /* If it has exited notify the new parent about this child's death. */
612 0 : if (!p->ptrace &&
613 0 : p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
614 0 : if (do_notify_parent(p, p->exit_signal)) {
615 0 : p->exit_state = EXIT_DEAD;
616 0 : list_add(&p->ptrace_entry, dead);
617 : }
618 : }
619 :
620 0 : 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 93 : static void forget_original_parent(struct task_struct *father,
632 : struct list_head *dead)
633 : {
634 : struct task_struct *p, *t, *reaper;
635 :
636 186 : if (unlikely(!list_empty(&father->ptraced)))
637 0 : exit_ptrace(father, dead);
638 :
639 : /* Can drop and reacquire tasklist_lock */
640 93 : reaper = find_child_reaper(father, dead);
641 186 : if (list_empty(&father->children))
642 : return;
643 :
644 0 : reaper = find_new_reaper(father, reaper);
645 0 : list_for_each_entry(p, &father->children, sibling) {
646 0 : for_each_thread(p, t) {
647 0 : RCU_INIT_POINTER(t->real_parent, reaper);
648 0 : BUG_ON((!t->ptrace) != (rcu_access_pointer(t->parent) == father));
649 0 : if (likely(!t->ptrace))
650 0 : t->parent = t->real_parent;
651 0 : if (t->pdeath_signal)
652 0 : 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 0 : if (!same_thread_group(reaper, father))
661 0 : reparent_leader(father, p, dead);
662 : }
663 0 : 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 93 : static void exit_notify(struct task_struct *tsk, int group_dead)
671 : {
672 : bool autoreap;
673 : struct task_struct *p, *n;
674 93 : LIST_HEAD(dead);
675 :
676 93 : write_lock_irq(&tasklist_lock);
677 93 : forget_original_parent(tsk, &dead);
678 :
679 93 : if (group_dead)
680 93 : kill_orphaned_pgrp(tsk->group_leader, NULL);
681 :
682 93 : tsk->exit_state = EXIT_ZOMBIE;
683 93 : if (unlikely(tsk->ptrace)) {
684 0 : int sig = thread_group_leader(tsk) &&
685 0 : thread_group_empty(tsk) &&
686 0 : !ptrace_reparented(tsk) ?
687 0 : tsk->exit_signal : SIGCHLD;
688 0 : autoreap = do_notify_parent(tsk, sig);
689 93 : } else if (thread_group_leader(tsk)) {
690 186 : autoreap = thread_group_empty(tsk) &&
691 93 : do_notify_parent(tsk, tsk->exit_signal);
692 : } else {
693 : autoreap = true;
694 : }
695 :
696 93 : if (autoreap) {
697 93 : tsk->exit_state = EXIT_DEAD;
698 93 : list_add(&tsk->ptrace_entry, &dead);
699 : }
700 :
701 : /* mt-exec, de_thread() is waiting for group leader */
702 93 : if (unlikely(tsk->signal->notify_count < 0))
703 0 : wake_up_process(tsk->signal->group_exec_task);
704 93 : write_unlock_irq(&tasklist_lock);
705 :
706 186 : list_for_each_entry_safe(p, n, &dead, ptrace_entry) {
707 186 : list_del_init(&p->ptrace_entry);
708 93 : release_task(p);
709 : }
710 93 : }
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 93 : void __noreturn do_exit(long code)
737 : {
738 93 : struct task_struct *tsk = current;
739 : int group_dead;
740 :
741 93 : WARN_ON(tsk->plug);
742 :
743 93 : kcov_task_exit(tsk);
744 :
745 93 : coredump_task_exit(tsk);
746 93 : ptrace_event(PTRACE_EVENT_EXIT, code);
747 :
748 93 : validate_creds_for_do_exit(tsk);
749 :
750 93 : io_uring_files_cancel();
751 93 : 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 93 : acct_update_integrals(tsk);
757 186 : group_dead = atomic_dec_and_test(&tsk->signal->live);
758 93 : if (group_dead) {
759 : /*
760 : * If the last thread of global init has exited, panic
761 : * immediately to get a useable coredump.
762 : */
763 93 : if (unlikely(is_global_init(tsk)))
764 0 : panic("Attempted to kill init! exitcode=0x%08x\n",
765 0 : tsk->signal->group_exit_code ?: (int)code);
766 :
767 : #ifdef CONFIG_POSIX_TIMERS
768 93 : hrtimer_cancel(&tsk->signal->real_timer);
769 93 : exit_itimers(tsk->signal);
770 : #endif
771 93 : if (tsk->mm)
772 0 : 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 93 : audit_free(tsk);
778 :
779 93 : tsk->exit_code = code;
780 93 : taskstats_exit(tsk, group_dead);
781 :
782 93 : exit_mm();
783 :
784 : if (group_dead)
785 : acct_process();
786 93 : trace_sched_process_exit(tsk);
787 :
788 93 : exit_sem(tsk);
789 93 : exit_shm(tsk);
790 93 : exit_files(tsk);
791 93 : exit_fs(tsk);
792 93 : if (group_dead)
793 93 : disassociate_ctty(1);
794 93 : exit_task_namespaces(tsk);
795 93 : exit_task_work(tsk);
796 93 : 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 93 : perf_event_exit_task(tsk);
805 :
806 93 : sched_autogroup_exit_task(tsk);
807 93 : cgroup_exit(tsk);
808 :
809 : /*
810 : * FIXME: do that only when needed, using sched_exit tracepoint
811 : */
812 93 : flush_ptrace_hw_breakpoint(tsk);
813 :
814 : exit_tasks_rcu_start();
815 93 : exit_notify(tsk, group_dead);
816 93 : proc_exit_connector(tsk);
817 93 : mpol_put_task_policy(tsk);
818 : #ifdef CONFIG_FUTEX
819 93 : if (unlikely(current->pi_state_cache))
820 0 : 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 93 : if (tsk->io_context)
828 0 : exit_io_context(tsk);
829 :
830 93 : if (tsk->splice_pipe)
831 0 : free_pipe_info(tsk->splice_pipe);
832 :
833 93 : if (tsk->task_frag.page)
834 0 : put_page(tsk->task_frag.page);
835 :
836 93 : validate_creds_for_do_exit(tsk);
837 93 : exit_task_stack_account(tsk);
838 :
839 : check_stack_usage();
840 93 : preempt_disable();
841 93 : if (tsk->nr_dirtied)
842 0 : __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
843 : exit_rcu();
844 : exit_tasks_rcu_finish();
845 :
846 93 : lockdep_free_task(tsk);
847 93 : do_task_dead();
848 : }
849 :
850 0 : 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 0 : struct task_struct *tsk = current;
862 :
863 0 : if (unlikely(in_interrupt()))
864 0 : panic("Aiee, killing interrupt handler!");
865 0 : if (unlikely(!tsk->pid))
866 0 : panic("Attempted to kill the idle task!");
867 :
868 0 : if (unlikely(in_atomic())) {
869 0 : 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 0 : if (unlikely(tsk->flags & PF_EXITING)) {
880 0 : pr_alert("Fixing recursive fault but reboot is needed!\n");
881 0 : futex_exit_recursive(tsk);
882 0 : tsk->exit_state = EXIT_DEAD;
883 0 : refcount_inc(&tsk->rcu_users);
884 0 : do_task_dead();
885 : }
886 :
887 0 : do_exit(signr);
888 : }
889 :
890 0 : SYSCALL_DEFINE1(exit, int, error_code)
891 : {
892 0 : 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 0 : do_group_exit(int exit_code)
901 : {
902 0 : struct signal_struct *sig = current->signal;
903 :
904 0 : if (sig->flags & SIGNAL_GROUP_EXIT)
905 0 : exit_code = sig->group_exit_code;
906 0 : else if (sig->group_exec_task)
907 : exit_code = 0;
908 0 : else if (!thread_group_empty(current)) {
909 0 : struct sighand_struct *const sighand = current->sighand;
910 :
911 0 : spin_lock_irq(&sighand->siglock);
912 0 : if (sig->flags & SIGNAL_GROUP_EXIT)
913 : /* Another thread got here before we took the lock. */
914 0 : exit_code = sig->group_exit_code;
915 0 : else if (sig->group_exec_task)
916 : exit_code = 0;
917 : else {
918 0 : sig->group_exit_code = exit_code;
919 0 : sig->flags = SIGNAL_GROUP_EXIT;
920 0 : zap_other_threads(current);
921 : }
922 0 : spin_unlock_irq(&sighand->siglock);
923 : }
924 :
925 0 : 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 0 : SYSCALL_DEFINE1(exit_group, int, error_code)
935 : {
936 0 : 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 0 : return wo->wo_type == PIDTYPE_MAX ||
964 0 : task_pid_type(p, wo->wo_type) == wo->wo_pid;
965 : }
966 :
967 : static int
968 0 : eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p)
969 : {
970 0 : 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 0 : 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 0 : if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
989 : return 0;
990 :
991 0 : 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 0 : static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
1001 : {
1002 : int state, status;
1003 0 : pid_t pid = task_pid_vnr(p);
1004 0 : uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
1005 : struct waitid_info *infop;
1006 :
1007 0 : if (!likely(wo->wo_flags & WEXITED))
1008 : return 0;
1009 :
1010 0 : if (unlikely(wo->wo_flags & WNOWAIT)) {
1011 0 : status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1012 0 : ? p->signal->group_exit_code : p->exit_code;
1013 0 : get_task_struct(p);
1014 0 : read_unlock(&tasklist_lock);
1015 : sched_annotate_sleep();
1016 0 : if (wo->wo_rusage)
1017 0 : getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1018 0 : put_task_struct(p);
1019 0 : goto out_info;
1020 : }
1021 : /*
1022 : * Move the task's state to DEAD/TRACE, only one thread can do this.
1023 : */
1024 0 : state = (ptrace_reparented(p) && thread_group_leader(p)) ?
1025 0 : EXIT_TRACE : EXIT_DEAD;
1026 0 : 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 0 : read_unlock(&tasklist_lock);
1032 : sched_annotate_sleep();
1033 :
1034 : /*
1035 : * Check thread_group_leader() to exclude the traced sub-threads.
1036 : */
1037 0 : if (state == EXIT_DEAD && thread_group_leader(p)) {
1038 0 : struct signal_struct *sig = p->signal;
1039 0 : 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 0 : thread_group_cputime_adjusted(p, &tgutime, &tgstime);
1064 0 : spin_lock_irq(¤t->sighand->siglock);
1065 0 : write_seqlock(&psig->stats_lock);
1066 0 : psig->cutime += tgutime + sig->cutime;
1067 0 : psig->cstime += tgstime + sig->cstime;
1068 0 : psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
1069 0 : psig->cmin_flt +=
1070 0 : p->min_flt + sig->min_flt + sig->cmin_flt;
1071 0 : psig->cmaj_flt +=
1072 0 : p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1073 0 : psig->cnvcsw +=
1074 0 : p->nvcsw + sig->nvcsw + sig->cnvcsw;
1075 0 : psig->cnivcsw +=
1076 0 : p->nivcsw + sig->nivcsw + sig->cnivcsw;
1077 0 : psig->cinblock +=
1078 0 : task_io_get_inblock(p) +
1079 0 : sig->inblock + sig->cinblock;
1080 0 : psig->coublock +=
1081 0 : task_io_get_oublock(p) +
1082 0 : sig->oublock + sig->coublock;
1083 0 : maxrss = max(sig->maxrss, sig->cmaxrss);
1084 0 : if (psig->cmaxrss < maxrss)
1085 0 : psig->cmaxrss = maxrss;
1086 0 : task_io_accounting_add(&psig->ioac, &p->ioac);
1087 0 : task_io_accounting_add(&psig->ioac, &sig->ioac);
1088 0 : write_sequnlock(&psig->stats_lock);
1089 0 : spin_unlock_irq(¤t->sighand->siglock);
1090 : }
1091 :
1092 0 : if (wo->wo_rusage)
1093 0 : getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1094 0 : status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1095 0 : ? p->signal->group_exit_code : p->exit_code;
1096 0 : wo->wo_stat = status;
1097 :
1098 0 : if (state == EXIT_TRACE) {
1099 0 : write_lock_irq(&tasklist_lock);
1100 : /* We dropped tasklist, ptracer could die and untrace */
1101 0 : ptrace_unlink(p);
1102 :
1103 : /* If parent wants a zombie, don't release it now */
1104 0 : state = EXIT_ZOMBIE;
1105 0 : if (do_notify_parent(p, p->exit_signal))
1106 0 : state = EXIT_DEAD;
1107 0 : p->exit_state = state;
1108 0 : write_unlock_irq(&tasklist_lock);
1109 : }
1110 0 : if (state == EXIT_DEAD)
1111 0 : release_task(p);
1112 :
1113 : out_info:
1114 0 : infop = wo->wo_info;
1115 0 : if (infop) {
1116 0 : if ((status & 0x7f) == 0) {
1117 0 : infop->cause = CLD_EXITED;
1118 0 : infop->status = status >> 8;
1119 : } else {
1120 0 : infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1121 0 : infop->status = status & 0x7f;
1122 : }
1123 0 : infop->pid = pid;
1124 0 : infop->uid = uid;
1125 : }
1126 :
1127 : return pid;
1128 : }
1129 :
1130 : static int *task_stopped_code(struct task_struct *p, bool ptrace)
1131 : {
1132 0 : if (ptrace) {
1133 0 : if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING))
1134 0 : return &p->exit_code;
1135 : } else {
1136 0 : if (p->signal->flags & SIGNAL_STOP_STOPPED)
1137 0 : 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 0 : 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 0 : 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 0 : if (!ptrace && !(wo->wo_flags & WUNTRACED))
1172 : return 0;
1173 :
1174 0 : if (!task_stopped_code(p, ptrace))
1175 : return 0;
1176 :
1177 0 : exit_code = 0;
1178 0 : spin_lock_irq(&p->sighand->siglock);
1179 :
1180 0 : p_code = task_stopped_code(p, ptrace);
1181 0 : if (unlikely(!p_code))
1182 : goto unlock_sig;
1183 :
1184 0 : exit_code = *p_code;
1185 0 : if (!exit_code)
1186 : goto unlock_sig;
1187 :
1188 0 : if (!unlikely(wo->wo_flags & WNOWAIT))
1189 0 : *p_code = 0;
1190 :
1191 0 : uid = from_kuid_munged(current_user_ns(), task_uid(p));
1192 : unlock_sig:
1193 0 : spin_unlock_irq(&p->sighand->siglock);
1194 0 : 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 0 : get_task_struct(p);
1205 0 : pid = task_pid_vnr(p);
1206 0 : why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1207 0 : read_unlock(&tasklist_lock);
1208 : sched_annotate_sleep();
1209 0 : if (wo->wo_rusage)
1210 0 : getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1211 0 : put_task_struct(p);
1212 :
1213 0 : if (likely(!(wo->wo_flags & WNOWAIT)))
1214 0 : wo->wo_stat = (exit_code << 8) | 0x7f;
1215 :
1216 0 : infop = wo->wo_info;
1217 0 : if (infop) {
1218 0 : infop->cause = why;
1219 0 : infop->status = exit_code;
1220 0 : infop->pid = pid;
1221 0 : 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 0 : 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 0 : if (!unlikely(wo->wo_flags & WCONTINUED))
1239 : return 0;
1240 :
1241 0 : if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1242 : return 0;
1243 :
1244 0 : spin_lock_irq(&p->sighand->siglock);
1245 : /* Re-check with the lock held. */
1246 0 : if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1247 0 : spin_unlock_irq(&p->sighand->siglock);
1248 0 : return 0;
1249 : }
1250 0 : if (!unlikely(wo->wo_flags & WNOWAIT))
1251 0 : p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1252 0 : uid = from_kuid_munged(current_user_ns(), task_uid(p));
1253 0 : spin_unlock_irq(&p->sighand->siglock);
1254 :
1255 0 : pid = task_pid_vnr(p);
1256 0 : get_task_struct(p);
1257 0 : read_unlock(&tasklist_lock);
1258 : sched_annotate_sleep();
1259 0 : if (wo->wo_rusage)
1260 0 : getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1261 0 : put_task_struct(p);
1262 :
1263 0 : infop = wo->wo_info;
1264 0 : if (!infop) {
1265 0 : wo->wo_stat = 0xffff;
1266 : } else {
1267 0 : infop->cause = CLD_CONTINUED;
1268 0 : infop->pid = pid;
1269 0 : infop->uid = uid;
1270 0 : 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 0 : 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 0 : int exit_state = READ_ONCE(p->exit_state);
1293 : int ret;
1294 :
1295 0 : if (unlikely(exit_state == EXIT_DEAD))
1296 : return 0;
1297 :
1298 0 : ret = eligible_child(wo, ptrace, p);
1299 0 : if (!ret)
1300 : return ret;
1301 :
1302 0 : 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 0 : if (likely(!ptrace))
1308 0 : wo->notask_error = 0;
1309 : return 0;
1310 : }
1311 :
1312 0 : 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 0 : if (!ptrace_reparented(p))
1325 0 : ptrace = 1;
1326 : }
1327 :
1328 : /* slay zombie? */
1329 0 : if (exit_state == EXIT_ZOMBIE) {
1330 : /* we don't reap group leaders with subthreads */
1331 0 : 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 0 : if (unlikely(ptrace) || likely(!p->ptrace))
1338 0 : 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 0 : if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1362 0 : 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 0 : 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 0 : ret = wait_task_stopped(wo, ptrace, p);
1376 0 : 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 0 : 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 0 : static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1397 : {
1398 : struct task_struct *p;
1399 :
1400 0 : list_for_each_entry(p, &tsk->children, sibling) {
1401 0 : int ret = wait_consider_task(wo, 0, p);
1402 :
1403 0 : if (ret)
1404 : return ret;
1405 : }
1406 :
1407 : return 0;
1408 : }
1409 :
1410 0 : static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1411 : {
1412 : struct task_struct *p;
1413 :
1414 0 : list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1415 0 : int ret = wait_consider_task(wo, 1, p);
1416 :
1417 0 : if (ret)
1418 : return ret;
1419 : }
1420 :
1421 : return 0;
1422 : }
1423 :
1424 0 : static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode,
1425 : int sync, void *key)
1426 : {
1427 0 : struct wait_opts *wo = container_of(wait, struct wait_opts,
1428 : child_wait);
1429 0 : struct task_struct *p = key;
1430 :
1431 0 : if (!eligible_pid(wo, p))
1432 : return 0;
1433 :
1434 0 : if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1435 : return 0;
1436 :
1437 0 : return default_wake_function(wait, mode, sync, key);
1438 : }
1439 :
1440 93 : void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1441 : {
1442 93 : __wake_up_sync_key(&parent->signal->wait_chldexit,
1443 : TASK_INTERRUPTIBLE, p);
1444 93 : }
1445 :
1446 : static bool is_effectively_child(struct wait_opts *wo, bool ptrace,
1447 : struct task_struct *target)
1448 : {
1449 0 : struct task_struct *parent =
1450 0 : !ptrace ? target->real_parent : target->parent;
1451 :
1452 0 : return current == parent || (!(wo->wo_flags & __WNOTHREAD) &&
1453 0 : 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 0 : static int do_wait_pid(struct wait_opts *wo)
1461 : {
1462 : bool ptrace;
1463 : struct task_struct *target;
1464 : int retval;
1465 :
1466 0 : ptrace = false;
1467 0 : target = pid_task(wo->wo_pid, PIDTYPE_TGID);
1468 0 : if (target && is_effectively_child(wo, ptrace, target)) {
1469 0 : retval = wait_consider_task(wo, ptrace, target);
1470 0 : if (retval)
1471 : return retval;
1472 : }
1473 :
1474 0 : ptrace = true;
1475 0 : target = pid_task(wo->wo_pid, PIDTYPE_PID);
1476 0 : if (target && target->ptrace &&
1477 0 : is_effectively_child(wo, ptrace, target)) {
1478 0 : retval = wait_consider_task(wo, ptrace, target);
1479 0 : if (retval)
1480 : return retval;
1481 : }
1482 :
1483 : return 0;
1484 : }
1485 :
1486 0 : static long do_wait(struct wait_opts *wo)
1487 : {
1488 : int retval;
1489 :
1490 0 : trace_sched_process_wait(wo->wo_pid);
1491 :
1492 0 : init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1493 0 : wo->child_wait.private = current;
1494 0 : 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 0 : wo->notask_error = -ECHILD;
1503 0 : if ((wo->wo_type < PIDTYPE_MAX) &&
1504 0 : (!wo->wo_pid || !pid_has_task(wo->wo_pid, wo->wo_type)))
1505 : goto notask;
1506 :
1507 0 : set_current_state(TASK_INTERRUPTIBLE);
1508 0 : read_lock(&tasklist_lock);
1509 :
1510 0 : if (wo->wo_type == PIDTYPE_PID) {
1511 0 : retval = do_wait_pid(wo);
1512 0 : if (retval)
1513 : goto end;
1514 : } else {
1515 0 : struct task_struct *tsk = current;
1516 :
1517 : do {
1518 0 : retval = do_wait_thread(wo, tsk);
1519 0 : if (retval)
1520 : goto end;
1521 :
1522 0 : retval = ptrace_do_wait(wo, tsk);
1523 0 : if (retval)
1524 : goto end;
1525 :
1526 0 : if (wo->wo_flags & __WNOTHREAD)
1527 : break;
1528 0 : } while_each_thread(current, tsk);
1529 : }
1530 0 : read_unlock(&tasklist_lock);
1531 :
1532 : notask:
1533 0 : retval = wo->notask_error;
1534 0 : if (!retval && !(wo->wo_flags & WNOHANG)) {
1535 0 : retval = -ERESTARTSYS;
1536 0 : if (!signal_pending(current)) {
1537 0 : schedule();
1538 0 : goto repeat;
1539 : }
1540 : }
1541 : end:
1542 0 : __set_current_state(TASK_RUNNING);
1543 0 : remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1544 0 : return retval;
1545 : }
1546 :
1547 0 : 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 0 : struct pid *pid = NULL;
1552 : enum pid_type type;
1553 : long ret;
1554 0 : unsigned int f_flags = 0;
1555 :
1556 0 : if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED|
1557 : __WNOTHREAD|__WCLONE|__WALL))
1558 : return -EINVAL;
1559 0 : if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1560 : return -EINVAL;
1561 :
1562 0 : switch (which) {
1563 : case P_ALL:
1564 : type = PIDTYPE_MAX;
1565 : break;
1566 : case P_PID:
1567 0 : type = PIDTYPE_PID;
1568 0 : if (upid <= 0)
1569 : return -EINVAL;
1570 :
1571 0 : pid = find_get_pid(upid);
1572 0 : break;
1573 : case P_PGID:
1574 0 : type = PIDTYPE_PGID;
1575 0 : if (upid < 0)
1576 : return -EINVAL;
1577 :
1578 0 : if (upid)
1579 0 : pid = find_get_pid(upid);
1580 : else
1581 0 : pid = get_task_pid(current, PIDTYPE_PGID);
1582 : break;
1583 : case P_PIDFD:
1584 0 : type = PIDTYPE_PID;
1585 0 : if (upid < 0)
1586 : return -EINVAL;
1587 :
1588 0 : pid = pidfd_get_pid(upid, &f_flags);
1589 0 : if (IS_ERR(pid))
1590 0 : return PTR_ERR(pid);
1591 :
1592 : break;
1593 : default:
1594 : return -EINVAL;
1595 : }
1596 :
1597 0 : wo.wo_type = type;
1598 0 : wo.wo_pid = pid;
1599 0 : wo.wo_flags = options;
1600 0 : wo.wo_info = infop;
1601 0 : wo.wo_rusage = ru;
1602 0 : if (f_flags & O_NONBLOCK)
1603 0 : wo.wo_flags |= WNOHANG;
1604 :
1605 0 : ret = do_wait(&wo);
1606 0 : if (!ret && !(options & WNOHANG) && (f_flags & O_NONBLOCK))
1607 0 : ret = -EAGAIN;
1608 :
1609 0 : put_pid(pid);
1610 0 : return ret;
1611 : }
1612 :
1613 0 : 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 0 : struct waitid_info info = {.status = 0};
1618 0 : long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL);
1619 0 : int signo = 0;
1620 :
1621 0 : if (err > 0) {
1622 0 : signo = SIGCHLD;
1623 0 : err = 0;
1624 0 : if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1625 : return -EFAULT;
1626 : }
1627 0 : if (!infop)
1628 : return err;
1629 :
1630 0 : if (!user_write_access_begin(infop, sizeof(*infop)))
1631 : return -EFAULT;
1632 :
1633 0 : unsafe_put_user(signo, &infop->si_signo, Efault);
1634 0 : unsafe_put_user(0, &infop->si_errno, Efault);
1635 0 : unsafe_put_user(info.cause, &infop->si_code, Efault);
1636 0 : unsafe_put_user(info.pid, &infop->si_pid, Efault);
1637 0 : unsafe_put_user(info.uid, &infop->si_uid, Efault);
1638 0 : 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 0 : long kernel_wait4(pid_t upid, int __user *stat_addr, int options,
1647 : struct rusage *ru)
1648 : {
1649 : struct wait_opts wo;
1650 0 : struct pid *pid = NULL;
1651 : enum pid_type type;
1652 : long ret;
1653 :
1654 0 : if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1655 : __WNOTHREAD|__WCLONE|__WALL))
1656 : return -EINVAL;
1657 :
1658 : /* -INT_MIN is not defined */
1659 0 : if (upid == INT_MIN)
1660 : return -ESRCH;
1661 :
1662 0 : if (upid == -1)
1663 : type = PIDTYPE_MAX;
1664 0 : else if (upid < 0) {
1665 0 : type = PIDTYPE_PGID;
1666 0 : pid = find_get_pid(-upid);
1667 0 : } else if (upid == 0) {
1668 0 : type = PIDTYPE_PGID;
1669 0 : pid = get_task_pid(current, PIDTYPE_PGID);
1670 : } else /* upid > 0 */ {
1671 0 : type = PIDTYPE_PID;
1672 0 : pid = find_get_pid(upid);
1673 : }
1674 :
1675 0 : wo.wo_type = type;
1676 0 : wo.wo_pid = pid;
1677 0 : wo.wo_flags = options | WEXITED;
1678 0 : wo.wo_info = NULL;
1679 0 : wo.wo_stat = 0;
1680 0 : wo.wo_rusage = ru;
1681 0 : ret = do_wait(&wo);
1682 0 : put_pid(pid);
1683 0 : if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr))
1684 0 : ret = -EFAULT;
1685 :
1686 : return ret;
1687 : }
1688 :
1689 0 : int kernel_wait(pid_t pid, int *stat)
1690 : {
1691 0 : struct wait_opts wo = {
1692 : .wo_type = PIDTYPE_PID,
1693 0 : .wo_pid = find_get_pid(pid),
1694 : .wo_flags = WEXITED,
1695 : };
1696 : int ret;
1697 :
1698 0 : ret = do_wait(&wo);
1699 0 : if (ret > 0 && wo.wo_stat)
1700 0 : *stat = wo.wo_stat;
1701 0 : put_pid(wo.wo_pid);
1702 0 : return ret;
1703 : }
1704 :
1705 0 : SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1706 : int, options, struct rusage __user *, ru)
1707 : {
1708 : struct rusage r;
1709 0 : long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL);
1710 :
1711 0 : if (err > 0) {
1712 0 : 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 0 : SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1725 : {
1726 0 : 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 0 : bool thread_group_exited(struct pid *pid)
1800 : {
1801 : struct task_struct *task;
1802 : bool exited;
1803 :
1804 : rcu_read_lock();
1805 0 : task = pid_task(pid, PIDTYPE_PID);
1806 0 : exited = !task ||
1807 0 : (READ_ONCE(task->exit_state) && thread_group_empty(task));
1808 : rcu_read_unlock();
1809 :
1810 0 : return exited;
1811 : }
1812 : EXPORT_SYMBOL(thread_group_exited);
1813 :
1814 0 : __weak void abort(void)
1815 : {
1816 0 : BUG();
1817 :
1818 : /* if that doesn't kill us, halt */
1819 : panic("Oops failed to kill thread");
1820 : }
1821 : EXPORT_SYMBOL(abort);
|
