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