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1 | /* | |
2 | * linux/kernel/exit.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | */ | |
6 | ||
7 | #include <linux/mm.h> | |
8 | #include <linux/slab.h> | |
9 | #include <linux/sched/autogroup.h> | |
10 | #include <linux/sched/mm.h> | |
11 | #include <linux/sched/stat.h> | |
12 | #include <linux/sched/task.h> | |
13 | #include <linux/sched/task_stack.h> | |
14 | #include <linux/sched/cputime.h> | |
15 | #include <linux/interrupt.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/capability.h> | |
18 | #include <linux/completion.h> | |
19 | #include <linux/personality.h> | |
20 | #include <linux/tty.h> | |
21 | #include <linux/iocontext.h> | |
22 | #include <linux/key.h> | |
23 | #include <linux/cpu.h> | |
24 | #include <linux/acct.h> | |
25 | #include <linux/tsacct_kern.h> | |
26 | #include <linux/file.h> | |
27 | #include <linux/fdtable.h> | |
28 | #include <linux/freezer.h> | |
29 | #include <linux/binfmts.h> | |
30 | #include <linux/nsproxy.h> | |
31 | #include <linux/pid_namespace.h> | |
32 | #include <linux/ptrace.h> | |
33 | #include <linux/profile.h> | |
34 | #include <linux/mount.h> | |
35 | #include <linux/proc_fs.h> | |
36 | #include <linux/kthread.h> | |
37 | #include <linux/mempolicy.h> | |
38 | #include <linux/taskstats_kern.h> | |
39 | #include <linux/delayacct.h> | |
40 | #include <linux/cgroup.h> | |
41 | #include <linux/syscalls.h> | |
42 | #include <linux/signal.h> | |
43 | #include <linux/posix-timers.h> | |
44 | #include <linux/cn_proc.h> | |
45 | #include <linux/mutex.h> | |
46 | #include <linux/futex.h> | |
47 | #include <linux/pipe_fs_i.h> | |
48 | #include <linux/audit.h> /* for audit_free() */ | |
49 | #include <linux/resource.h> | |
50 | #include <linux/blkdev.h> | |
51 | #include <linux/task_io_accounting_ops.h> | |
52 | #include <linux/tracehook.h> | |
53 | #include <linux/fs_struct.h> | |
54 | #include <linux/init_task.h> | |
55 | #include <linux/perf_event.h> | |
56 | #include <trace/events/sched.h> | |
57 | #include <linux/hw_breakpoint.h> | |
58 | #include <linux/oom.h> | |
59 | #include <linux/writeback.h> | |
60 | #include <linux/shm.h> | |
61 | #include <linux/kcov.h> | |
62 | #include <linux/random.h> | |
63 | #include <linux/rcuwait.h> | |
64 | #include <linux/compat.h> | |
65 | ||
66 | #include <linux/uaccess.h> | |
67 | #include <asm/unistd.h> | |
68 | #include <asm/pgtable.h> | |
69 | #include <asm/mmu_context.h> | |
70 | ||
71 | static void __unhash_process(struct task_struct *p, bool group_dead) | |
72 | { | |
73 | nr_threads--; | |
74 | detach_pid(p, PIDTYPE_PID); | |
75 | if (group_dead) { | |
76 | detach_pid(p, PIDTYPE_PGID); | |
77 | detach_pid(p, PIDTYPE_SID); | |
78 | ||
79 | list_del_rcu(&p->tasks); | |
80 | list_del_init(&p->sibling); | |
81 | __this_cpu_dec(process_counts); | |
82 | } | |
83 | list_del_rcu(&p->thread_group); | |
84 | list_del_rcu(&p->thread_node); | |
85 | } | |
86 | ||
87 | /* | |
88 | * This function expects the tasklist_lock write-locked. | |
89 | */ | |
90 | static void __exit_signal(struct task_struct *tsk) | |
91 | { | |
92 | struct signal_struct *sig = tsk->signal; | |
93 | bool group_dead = thread_group_leader(tsk); | |
94 | struct sighand_struct *sighand; | |
95 | struct tty_struct *uninitialized_var(tty); | |
96 | u64 utime, stime; | |
97 | ||
98 | sighand = rcu_dereference_check(tsk->sighand, | |
99 | lockdep_tasklist_lock_is_held()); | |
100 | spin_lock(&sighand->siglock); | |
101 | ||
102 | #ifdef CONFIG_POSIX_TIMERS | |
103 | posix_cpu_timers_exit(tsk); | |
104 | if (group_dead) { | |
105 | posix_cpu_timers_exit_group(tsk); | |
106 | } else { | |
107 | /* | |
108 | * This can only happen if the caller is de_thread(). | |
109 | * FIXME: this is the temporary hack, we should teach | |
110 | * posix-cpu-timers to handle this case correctly. | |
111 | */ | |
112 | if (unlikely(has_group_leader_pid(tsk))) | |
113 | posix_cpu_timers_exit_group(tsk); | |
114 | } | |
115 | #endif | |
116 | ||
117 | if (group_dead) { | |
118 | tty = sig->tty; | |
119 | sig->tty = NULL; | |
120 | } else { | |
121 | /* | |
122 | * If there is any task waiting for the group exit | |
123 | * then notify it: | |
124 | */ | |
125 | if (sig->notify_count > 0 && !--sig->notify_count) | |
126 | wake_up_process(sig->group_exit_task); | |
127 | ||
128 | if (tsk == sig->curr_target) | |
129 | sig->curr_target = next_thread(tsk); | |
130 | } | |
131 | ||
132 | add_device_randomness((const void*) &tsk->se.sum_exec_runtime, | |
133 | sizeof(unsigned long long)); | |
134 | ||
135 | /* | |
136 | * Accumulate here the counters for all threads as they die. We could | |
137 | * skip the group leader because it is the last user of signal_struct, | |
138 | * but we want to avoid the race with thread_group_cputime() which can | |
139 | * see the empty ->thread_head list. | |
140 | */ | |
141 | task_cputime(tsk, &utime, &stime); | |
142 | write_seqlock(&sig->stats_lock); | |
143 | sig->utime += utime; | |
144 | sig->stime += stime; | |
145 | sig->gtime += task_gtime(tsk); | |
146 | sig->min_flt += tsk->min_flt; | |
147 | sig->maj_flt += tsk->maj_flt; | |
148 | sig->nvcsw += tsk->nvcsw; | |
149 | sig->nivcsw += tsk->nivcsw; | |
150 | sig->inblock += task_io_get_inblock(tsk); | |
151 | sig->oublock += task_io_get_oublock(tsk); | |
152 | task_io_accounting_add(&sig->ioac, &tsk->ioac); | |
153 | sig->sum_sched_runtime += tsk->se.sum_exec_runtime; | |
154 | sig->nr_threads--; | |
155 | __unhash_process(tsk, group_dead); | |
156 | write_sequnlock(&sig->stats_lock); | |
157 | ||
158 | /* | |
159 | * Do this under ->siglock, we can race with another thread | |
160 | * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. | |
161 | */ | |
162 | flush_sigqueue(&tsk->pending); | |
163 | tsk->sighand = NULL; | |
164 | spin_unlock(&sighand->siglock); | |
165 | ||
166 | __cleanup_sighand(sighand); | |
167 | clear_tsk_thread_flag(tsk, TIF_SIGPENDING); | |
168 | if (group_dead) { | |
169 | flush_sigqueue(&sig->shared_pending); | |
170 | tty_kref_put(tty); | |
171 | } | |
172 | } | |
173 | ||
174 | static void delayed_put_task_struct(struct rcu_head *rhp) | |
175 | { | |
176 | struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); | |
177 | ||
178 | perf_event_delayed_put(tsk); | |
179 | trace_sched_process_free(tsk); | |
180 | put_task_struct(tsk); | |
181 | } | |
182 | ||
183 | ||
184 | void release_task(struct task_struct *p) | |
185 | { | |
186 | struct task_struct *leader; | |
187 | int zap_leader; | |
188 | repeat: | |
189 | /* don't need to get the RCU readlock here - the process is dead and | |
190 | * can't be modifying its own credentials. But shut RCU-lockdep up */ | |
191 | rcu_read_lock(); | |
192 | atomic_dec(&__task_cred(p)->user->processes); | |
193 | rcu_read_unlock(); | |
194 | ||
195 | proc_flush_task(p); | |
196 | cgroup_release(p); | |
197 | ||
198 | write_lock_irq(&tasklist_lock); | |
199 | ptrace_release_task(p); | |
200 | __exit_signal(p); | |
201 | ||
202 | /* | |
203 | * If we are the last non-leader member of the thread | |
204 | * group, and the leader is zombie, then notify the | |
205 | * group leader's parent process. (if it wants notification.) | |
206 | */ | |
207 | zap_leader = 0; | |
208 | leader = p->group_leader; | |
209 | if (leader != p && thread_group_empty(leader) | |
210 | && leader->exit_state == EXIT_ZOMBIE) { | |
211 | /* | |
212 | * If we were the last child thread and the leader has | |
213 | * exited already, and the leader's parent ignores SIGCHLD, | |
214 | * then we are the one who should release the leader. | |
215 | */ | |
216 | zap_leader = do_notify_parent(leader, leader->exit_signal); | |
217 | if (zap_leader) | |
218 | leader->exit_state = EXIT_DEAD; | |
219 | } | |
220 | ||
221 | write_unlock_irq(&tasklist_lock); | |
222 | release_thread(p); | |
223 | call_rcu(&p->rcu, delayed_put_task_struct); | |
224 | ||
225 | p = leader; | |
226 | if (unlikely(zap_leader)) | |
227 | goto repeat; | |
228 | } | |
229 | ||
230 | /* | |
231 | * Note that if this function returns a valid task_struct pointer (!NULL) | |
232 | * task->usage must remain >0 for the duration of the RCU critical section. | |
233 | */ | |
234 | struct task_struct *task_rcu_dereference(struct task_struct **ptask) | |
235 | { | |
236 | struct sighand_struct *sighand; | |
237 | struct task_struct *task; | |
238 | ||
239 | /* | |
240 | * We need to verify that release_task() was not called and thus | |
241 | * delayed_put_task_struct() can't run and drop the last reference | |
242 | * before rcu_read_unlock(). We check task->sighand != NULL, | |
243 | * but we can read the already freed and reused memory. | |
244 | */ | |
245 | retry: | |
246 | task = rcu_dereference(*ptask); | |
247 | if (!task) | |
248 | return NULL; | |
249 | ||
250 | probe_kernel_address(&task->sighand, sighand); | |
251 | ||
252 | /* | |
253 | * Pairs with atomic_dec_and_test() in put_task_struct(). If this task | |
254 | * was already freed we can not miss the preceding update of this | |
255 | * pointer. | |
256 | */ | |
257 | smp_rmb(); | |
258 | if (unlikely(task != READ_ONCE(*ptask))) | |
259 | goto retry; | |
260 | ||
261 | /* | |
262 | * We've re-checked that "task == *ptask", now we have two different | |
263 | * cases: | |
264 | * | |
265 | * 1. This is actually the same task/task_struct. In this case | |
266 | * sighand != NULL tells us it is still alive. | |
267 | * | |
268 | * 2. This is another task which got the same memory for task_struct. | |
269 | * We can't know this of course, and we can not trust | |
270 | * sighand != NULL. | |
271 | * | |
272 | * In this case we actually return a random value, but this is | |
273 | * correct. | |
274 | * | |
275 | * If we return NULL - we can pretend that we actually noticed that | |
276 | * *ptask was updated when the previous task has exited. Or pretend | |
277 | * that probe_slab_address(&sighand) reads NULL. | |
278 | * | |
279 | * If we return the new task (because sighand is not NULL for any | |
280 | * reason) - this is fine too. This (new) task can't go away before | |
281 | * another gp pass. | |
282 | * | |
283 | * And note: We could even eliminate the false positive if re-read | |
284 | * task->sighand once again to avoid the falsely NULL. But this case | |
285 | * is very unlikely so we don't care. | |
286 | */ | |
287 | if (!sighand) | |
288 | return NULL; | |
289 | ||
290 | return task; | |
291 | } | |
292 | ||
293 | void rcuwait_wake_up(struct rcuwait *w) | |
294 | { | |
295 | struct task_struct *task; | |
296 | ||
297 | rcu_read_lock(); | |
298 | ||
299 | /* | |
300 | * Order condition vs @task, such that everything prior to the load | |
301 | * of @task is visible. This is the condition as to why the user called | |
302 | * rcuwait_trywake() in the first place. Pairs with set_current_state() | |
303 | * barrier (A) in rcuwait_wait_event(). | |
304 | * | |
305 | * WAIT WAKE | |
306 | * [S] tsk = current [S] cond = true | |
307 | * MB (A) MB (B) | |
308 | * [L] cond [L] tsk | |
309 | */ | |
310 | smp_mb(); /* (B) */ | |
311 | ||
312 | /* | |
313 | * Avoid using task_rcu_dereference() magic as long as we are careful, | |
314 | * see comment in rcuwait_wait_event() regarding ->exit_state. | |
315 | */ | |
316 | task = rcu_dereference(w->task); | |
317 | if (task) | |
318 | wake_up_process(task); | |
319 | rcu_read_unlock(); | |
320 | } | |
321 | ||
322 | /* | |
323 | * Determine if a process group is "orphaned", according to the POSIX | |
324 | * definition in 2.2.2.52. Orphaned process groups are not to be affected | |
325 | * by terminal-generated stop signals. Newly orphaned process groups are | |
326 | * to receive a SIGHUP and a SIGCONT. | |
327 | * | |
328 | * "I ask you, have you ever known what it is to be an orphan?" | |
329 | */ | |
330 | static int will_become_orphaned_pgrp(struct pid *pgrp, | |
331 | struct task_struct *ignored_task) | |
332 | { | |
333 | struct task_struct *p; | |
334 | ||
335 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { | |
336 | if ((p == ignored_task) || | |
337 | (p->exit_state && thread_group_empty(p)) || | |
338 | is_global_init(p->real_parent)) | |
339 | continue; | |
340 | ||
341 | if (task_pgrp(p->real_parent) != pgrp && | |
342 | task_session(p->real_parent) == task_session(p)) | |
343 | return 0; | |
344 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); | |
345 | ||
346 | return 1; | |
347 | } | |
348 | ||
349 | int is_current_pgrp_orphaned(void) | |
350 | { | |
351 | int retval; | |
352 | ||
353 | read_lock(&tasklist_lock); | |
354 | retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); | |
355 | read_unlock(&tasklist_lock); | |
356 | ||
357 | return retval; | |
358 | } | |
359 | ||
360 | static bool has_stopped_jobs(struct pid *pgrp) | |
361 | { | |
362 | struct task_struct *p; | |
363 | ||
364 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { | |
365 | if (p->signal->flags & SIGNAL_STOP_STOPPED) | |
366 | return true; | |
367 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); | |
368 | ||
369 | return false; | |
370 | } | |
371 | ||
372 | /* | |
373 | * Check to see if any process groups have become orphaned as | |
374 | * a result of our exiting, and if they have any stopped jobs, | |
375 | * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) | |
376 | */ | |
377 | static void | |
378 | kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) | |
379 | { | |
380 | struct pid *pgrp = task_pgrp(tsk); | |
381 | struct task_struct *ignored_task = tsk; | |
382 | ||
383 | if (!parent) | |
384 | /* exit: our father is in a different pgrp than | |
385 | * we are and we were the only connection outside. | |
386 | */ | |
387 | parent = tsk->real_parent; | |
388 | else | |
389 | /* reparent: our child is in a different pgrp than | |
390 | * we are, and it was the only connection outside. | |
391 | */ | |
392 | ignored_task = NULL; | |
393 | ||
394 | if (task_pgrp(parent) != pgrp && | |
395 | task_session(parent) == task_session(tsk) && | |
396 | will_become_orphaned_pgrp(pgrp, ignored_task) && | |
397 | has_stopped_jobs(pgrp)) { | |
398 | __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); | |
399 | __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); | |
400 | } | |
401 | } | |
402 | ||
403 | #ifdef CONFIG_MEMCG | |
404 | /* | |
405 | * A task is exiting. If it owned this mm, find a new owner for the mm. | |
406 | */ | |
407 | void mm_update_next_owner(struct mm_struct *mm) | |
408 | { | |
409 | struct task_struct *c, *g, *p = current; | |
410 | ||
411 | retry: | |
412 | /* | |
413 | * If the exiting or execing task is not the owner, it's | |
414 | * someone else's problem. | |
415 | */ | |
416 | if (mm->owner != p) | |
417 | return; | |
418 | /* | |
419 | * The current owner is exiting/execing and there are no other | |
420 | * candidates. Do not leave the mm pointing to a possibly | |
421 | * freed task structure. | |
422 | */ | |
423 | if (atomic_read(&mm->mm_users) <= 1) { | |
424 | mm->owner = NULL; | |
425 | return; | |
426 | } | |
427 | ||
428 | read_lock(&tasklist_lock); | |
429 | /* | |
430 | * Search in the children | |
431 | */ | |
432 | list_for_each_entry(c, &p->children, sibling) { | |
433 | if (c->mm == mm) | |
434 | goto assign_new_owner; | |
435 | } | |
436 | ||
437 | /* | |
438 | * Search in the siblings | |
439 | */ | |
440 | list_for_each_entry(c, &p->real_parent->children, sibling) { | |
441 | if (c->mm == mm) | |
442 | goto assign_new_owner; | |
443 | } | |
444 | ||
445 | /* | |
446 | * Search through everything else, we should not get here often. | |
447 | */ | |
448 | for_each_process(g) { | |
449 | if (g->flags & PF_KTHREAD) | |
450 | continue; | |
451 | for_each_thread(g, c) { | |
452 | if (c->mm == mm) | |
453 | goto assign_new_owner; | |
454 | if (c->mm) | |
455 | break; | |
456 | } | |
457 | } | |
458 | read_unlock(&tasklist_lock); | |
459 | /* | |
460 | * We found no owner yet mm_users > 1: this implies that we are | |
461 | * most likely racing with swapoff (try_to_unuse()) or /proc or | |
462 | * ptrace or page migration (get_task_mm()). Mark owner as NULL. | |
463 | */ | |
464 | mm->owner = NULL; | |
465 | return; | |
466 | ||
467 | assign_new_owner: | |
468 | BUG_ON(c == p); | |
469 | get_task_struct(c); | |
470 | /* | |
471 | * The task_lock protects c->mm from changing. | |
472 | * We always want mm->owner->mm == mm | |
473 | */ | |
474 | task_lock(c); | |
475 | /* | |
476 | * Delay read_unlock() till we have the task_lock() | |
477 | * to ensure that c does not slip away underneath us | |
478 | */ | |
479 | read_unlock(&tasklist_lock); | |
480 | if (c->mm != mm) { | |
481 | task_unlock(c); | |
482 | put_task_struct(c); | |
483 | goto retry; | |
484 | } | |
485 | mm->owner = c; | |
486 | task_unlock(c); | |
487 | put_task_struct(c); | |
488 | } | |
489 | #endif /* CONFIG_MEMCG */ | |
490 | ||
491 | /* | |
492 | * Turn us into a lazy TLB process if we | |
493 | * aren't already.. | |
494 | */ | |
495 | static void exit_mm(void) | |
496 | { | |
497 | struct mm_struct *mm = current->mm; | |
498 | struct core_state *core_state; | |
499 | ||
500 | exit_mm_release(current, mm); | |
501 | if (!mm) | |
502 | return; | |
503 | sync_mm_rss(mm); | |
504 | /* | |
505 | * Serialize with any possible pending coredump. | |
506 | * We must hold mmap_sem around checking core_state | |
507 | * and clearing tsk->mm. The core-inducing thread | |
508 | * will increment ->nr_threads for each thread in the | |
509 | * group with ->mm != NULL. | |
510 | */ | |
511 | down_read(&mm->mmap_sem); | |
512 | core_state = mm->core_state; | |
513 | if (core_state) { | |
514 | struct core_thread self; | |
515 | ||
516 | up_read(&mm->mmap_sem); | |
517 | ||
518 | self.task = current; | |
519 | self.next = xchg(&core_state->dumper.next, &self); | |
520 | /* | |
521 | * Implies mb(), the result of xchg() must be visible | |
522 | * to core_state->dumper. | |
523 | */ | |
524 | if (atomic_dec_and_test(&core_state->nr_threads)) | |
525 | complete(&core_state->startup); | |
526 | ||
527 | for (;;) { | |
528 | set_current_state(TASK_UNINTERRUPTIBLE); | |
529 | if (!self.task) /* see coredump_finish() */ | |
530 | break; | |
531 | freezable_schedule(); | |
532 | } | |
533 | __set_current_state(TASK_RUNNING); | |
534 | down_read(&mm->mmap_sem); | |
535 | } | |
536 | mmgrab(mm); | |
537 | BUG_ON(mm != current->active_mm); | |
538 | /* more a memory barrier than a real lock */ | |
539 | task_lock(current); | |
540 | current->mm = NULL; | |
541 | up_read(&mm->mmap_sem); | |
542 | enter_lazy_tlb(mm, current); | |
543 | task_unlock(current); | |
544 | mm_update_next_owner(mm); | |
545 | mmput(mm); | |
546 | if (test_thread_flag(TIF_MEMDIE)) | |
547 | exit_oom_victim(); | |
548 | } | |
549 | ||
550 | static struct task_struct *find_alive_thread(struct task_struct *p) | |
551 | { | |
552 | struct task_struct *t; | |
553 | ||
554 | for_each_thread(p, t) { | |
555 | if (!(t->flags & PF_EXITING)) | |
556 | return t; | |
557 | } | |
558 | return NULL; | |
559 | } | |
560 | ||
561 | static struct task_struct *find_child_reaper(struct task_struct *father, | |
562 | struct list_head *dead) | |
563 | __releases(&tasklist_lock) | |
564 | __acquires(&tasklist_lock) | |
565 | { | |
566 | struct pid_namespace *pid_ns = task_active_pid_ns(father); | |
567 | struct task_struct *reaper = pid_ns->child_reaper; | |
568 | struct task_struct *p, *n; | |
569 | ||
570 | if (likely(reaper != father)) | |
571 | return reaper; | |
572 | ||
573 | reaper = find_alive_thread(father); | |
574 | if (reaper) { | |
575 | pid_ns->child_reaper = reaper; | |
576 | return reaper; | |
577 | } | |
578 | ||
579 | write_unlock_irq(&tasklist_lock); | |
580 | ||
581 | list_for_each_entry_safe(p, n, dead, ptrace_entry) { | |
582 | list_del_init(&p->ptrace_entry); | |
583 | release_task(p); | |
584 | } | |
585 | ||
586 | zap_pid_ns_processes(pid_ns); | |
587 | write_lock_irq(&tasklist_lock); | |
588 | ||
589 | return father; | |
590 | } | |
591 | ||
592 | /* | |
593 | * When we die, we re-parent all our children, and try to: | |
594 | * 1. give them to another thread in our thread group, if such a member exists | |
595 | * 2. give it to the first ancestor process which prctl'd itself as a | |
596 | * child_subreaper for its children (like a service manager) | |
597 | * 3. give it to the init process (PID 1) in our pid namespace | |
598 | */ | |
599 | static struct task_struct *find_new_reaper(struct task_struct *father, | |
600 | struct task_struct *child_reaper) | |
601 | { | |
602 | struct task_struct *thread, *reaper; | |
603 | ||
604 | thread = find_alive_thread(father); | |
605 | if (thread) | |
606 | return thread; | |
607 | ||
608 | if (father->signal->has_child_subreaper) { | |
609 | unsigned int ns_level = task_pid(father)->level; | |
610 | /* | |
611 | * Find the first ->is_child_subreaper ancestor in our pid_ns. | |
612 | * We can't check reaper != child_reaper to ensure we do not | |
613 | * cross the namespaces, the exiting parent could be injected | |
614 | * by setns() + fork(). | |
615 | * We check pid->level, this is slightly more efficient than | |
616 | * task_active_pid_ns(reaper) != task_active_pid_ns(father). | |
617 | */ | |
618 | for (reaper = father->real_parent; | |
619 | task_pid(reaper)->level == ns_level; | |
620 | reaper = reaper->real_parent) { | |
621 | if (reaper == &init_task) | |
622 | break; | |
623 | if (!reaper->signal->is_child_subreaper) | |
624 | continue; | |
625 | thread = find_alive_thread(reaper); | |
626 | if (thread) | |
627 | return thread; | |
628 | } | |
629 | } | |
630 | ||
631 | return child_reaper; | |
632 | } | |
633 | ||
634 | /* | |
635 | * Any that need to be release_task'd are put on the @dead list. | |
636 | */ | |
637 | static void reparent_leader(struct task_struct *father, struct task_struct *p, | |
638 | struct list_head *dead) | |
639 | { | |
640 | if (unlikely(p->exit_state == EXIT_DEAD)) | |
641 | return; | |
642 | ||
643 | /* We don't want people slaying init. */ | |
644 | p->exit_signal = SIGCHLD; | |
645 | ||
646 | /* If it has exited notify the new parent about this child's death. */ | |
647 | if (!p->ptrace && | |
648 | p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { | |
649 | if (do_notify_parent(p, p->exit_signal)) { | |
650 | p->exit_state = EXIT_DEAD; | |
651 | list_add(&p->ptrace_entry, dead); | |
652 | } | |
653 | } | |
654 | ||
655 | kill_orphaned_pgrp(p, father); | |
656 | } | |
657 | ||
658 | /* | |
659 | * This does two things: | |
660 | * | |
661 | * A. Make init inherit all the child processes | |
662 | * B. Check to see if any process groups have become orphaned | |
663 | * as a result of our exiting, and if they have any stopped | |
664 | * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) | |
665 | */ | |
666 | static void forget_original_parent(struct task_struct *father, | |
667 | struct list_head *dead) | |
668 | { | |
669 | struct task_struct *p, *t, *reaper; | |
670 | ||
671 | if (unlikely(!list_empty(&father->ptraced))) | |
672 | exit_ptrace(father, dead); | |
673 | ||
674 | /* Can drop and reacquire tasklist_lock */ | |
675 | reaper = find_child_reaper(father, dead); | |
676 | if (list_empty(&father->children)) | |
677 | return; | |
678 | ||
679 | reaper = find_new_reaper(father, reaper); | |
680 | list_for_each_entry(p, &father->children, sibling) { | |
681 | for_each_thread(p, t) { | |
682 | t->real_parent = reaper; | |
683 | BUG_ON((!t->ptrace) != (t->parent == father)); | |
684 | if (likely(!t->ptrace)) | |
685 | t->parent = t->real_parent; | |
686 | if (t->pdeath_signal) | |
687 | group_send_sig_info(t->pdeath_signal, | |
688 | SEND_SIG_NOINFO, t); | |
689 | } | |
690 | /* | |
691 | * If this is a threaded reparent there is no need to | |
692 | * notify anyone anything has happened. | |
693 | */ | |
694 | if (!same_thread_group(reaper, father)) | |
695 | reparent_leader(father, p, dead); | |
696 | } | |
697 | list_splice_tail_init(&father->children, &reaper->children); | |
698 | } | |
699 | ||
700 | /* | |
701 | * Send signals to all our closest relatives so that they know | |
702 | * to properly mourn us.. | |
703 | */ | |
704 | static void exit_notify(struct task_struct *tsk, int group_dead) | |
705 | { | |
706 | bool autoreap; | |
707 | struct task_struct *p, *n; | |
708 | LIST_HEAD(dead); | |
709 | ||
710 | write_lock_irq(&tasklist_lock); | |
711 | forget_original_parent(tsk, &dead); | |
712 | ||
713 | if (group_dead) | |
714 | kill_orphaned_pgrp(tsk->group_leader, NULL); | |
715 | ||
716 | if (unlikely(tsk->ptrace)) { | |
717 | int sig = thread_group_leader(tsk) && | |
718 | thread_group_empty(tsk) && | |
719 | !ptrace_reparented(tsk) ? | |
720 | tsk->exit_signal : SIGCHLD; | |
721 | autoreap = do_notify_parent(tsk, sig); | |
722 | } else if (thread_group_leader(tsk)) { | |
723 | autoreap = thread_group_empty(tsk) && | |
724 | do_notify_parent(tsk, tsk->exit_signal); | |
725 | } else { | |
726 | autoreap = true; | |
727 | } | |
728 | ||
729 | tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE; | |
730 | if (tsk->exit_state == EXIT_DEAD) | |
731 | list_add(&tsk->ptrace_entry, &dead); | |
732 | ||
733 | /* mt-exec, de_thread() is waiting for group leader */ | |
734 | if (unlikely(tsk->signal->notify_count < 0)) | |
735 | wake_up_process(tsk->signal->group_exit_task); | |
736 | write_unlock_irq(&tasklist_lock); | |
737 | ||
738 | list_for_each_entry_safe(p, n, &dead, ptrace_entry) { | |
739 | list_del_init(&p->ptrace_entry); | |
740 | release_task(p); | |
741 | } | |
742 | } | |
743 | ||
744 | #ifdef CONFIG_DEBUG_STACK_USAGE | |
745 | static void check_stack_usage(void) | |
746 | { | |
747 | static DEFINE_SPINLOCK(low_water_lock); | |
748 | static int lowest_to_date = THREAD_SIZE; | |
749 | unsigned long free; | |
750 | ||
751 | free = stack_not_used(current); | |
752 | ||
753 | if (free >= lowest_to_date) | |
754 | return; | |
755 | ||
756 | spin_lock(&low_water_lock); | |
757 | if (free < lowest_to_date) { | |
758 | pr_info("%s (%d) used greatest stack depth: %lu bytes left\n", | |
759 | current->comm, task_pid_nr(current), free); | |
760 | lowest_to_date = free; | |
761 | } | |
762 | spin_unlock(&low_water_lock); | |
763 | } | |
764 | #else | |
765 | static inline void check_stack_usage(void) {} | |
766 | #endif | |
767 | ||
768 | void __noreturn do_exit(long code) | |
769 | { | |
770 | struct task_struct *tsk = current; | |
771 | int group_dead; | |
772 | ||
773 | profile_task_exit(tsk); | |
774 | kcov_task_exit(tsk); | |
775 | ||
776 | WARN_ON(blk_needs_flush_plug(tsk)); | |
777 | ||
778 | if (unlikely(in_interrupt())) | |
779 | panic("Aiee, killing interrupt handler!"); | |
780 | if (unlikely(!tsk->pid)) | |
781 | panic("Attempted to kill the idle task!"); | |
782 | ||
783 | /* | |
784 | * If do_exit is called because this processes oopsed, it's possible | |
785 | * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before | |
786 | * continuing. Amongst other possible reasons, this is to prevent | |
787 | * mm_release()->clear_child_tid() from writing to a user-controlled | |
788 | * kernel address. | |
789 | */ | |
790 | set_fs(USER_DS); | |
791 | ||
792 | ptrace_event(PTRACE_EVENT_EXIT, code); | |
793 | ||
794 | validate_creds_for_do_exit(tsk); | |
795 | ||
796 | /* | |
797 | * We're taking recursive faults here in do_exit. Safest is to just | |
798 | * leave this task alone and wait for reboot. | |
799 | */ | |
800 | if (unlikely(tsk->flags & PF_EXITING)) { | |
801 | pr_alert("Fixing recursive fault but reboot is needed!\n"); | |
802 | futex_exit_recursive(tsk); | |
803 | set_current_state(TASK_UNINTERRUPTIBLE); | |
804 | schedule(); | |
805 | } | |
806 | ||
807 | exit_signals(tsk); /* sets PF_EXITING */ | |
808 | ||
809 | if (unlikely(in_atomic())) { | |
810 | pr_info("note: %s[%d] exited with preempt_count %d\n", | |
811 | current->comm, task_pid_nr(current), | |
812 | preempt_count()); | |
813 | preempt_count_set(PREEMPT_ENABLED); | |
814 | } | |
815 | ||
816 | /* sync mm's RSS info before statistics gathering */ | |
817 | if (tsk->mm) | |
818 | sync_mm_rss(tsk->mm); | |
819 | acct_update_integrals(tsk); | |
820 | group_dead = atomic_dec_and_test(&tsk->signal->live); | |
821 | if (group_dead) { | |
822 | /* | |
823 | * If the last thread of global init has exited, panic | |
824 | * immediately to get a useable coredump. | |
825 | */ | |
826 | if (unlikely(is_global_init(tsk))) | |
827 | panic("Attempted to kill init! exitcode=0x%08x\n", | |
828 | tsk->signal->group_exit_code ?: (int)code); | |
829 | ||
830 | #ifdef CONFIG_POSIX_TIMERS | |
831 | hrtimer_cancel(&tsk->signal->real_timer); | |
832 | exit_itimers(tsk->signal); | |
833 | #endif | |
834 | if (tsk->mm) | |
835 | setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); | |
836 | } | |
837 | acct_collect(code, group_dead); | |
838 | if (group_dead) | |
839 | tty_audit_exit(); | |
840 | audit_free(tsk); | |
841 | ||
842 | tsk->exit_code = code; | |
843 | taskstats_exit(tsk, group_dead); | |
844 | ||
845 | exit_mm(); | |
846 | ||
847 | if (group_dead) | |
848 | acct_process(); | |
849 | trace_sched_process_exit(tsk); | |
850 | ||
851 | exit_sem(tsk); | |
852 | exit_shm(tsk); | |
853 | exit_files(tsk); | |
854 | exit_fs(tsk); | |
855 | if (group_dead) | |
856 | disassociate_ctty(1); | |
857 | exit_task_namespaces(tsk); | |
858 | exit_task_work(tsk); | |
859 | exit_thread(tsk); | |
860 | ||
861 | /* | |
862 | * Flush inherited counters to the parent - before the parent | |
863 | * gets woken up by child-exit notifications. | |
864 | * | |
865 | * because of cgroup mode, must be called before cgroup_exit() | |
866 | */ | |
867 | perf_event_exit_task(tsk); | |
868 | ||
869 | sched_autogroup_exit_task(tsk); | |
870 | cgroup_exit(tsk); | |
871 | ||
872 | /* | |
873 | * FIXME: do that only when needed, using sched_exit tracepoint | |
874 | */ | |
875 | flush_ptrace_hw_breakpoint(tsk); | |
876 | ||
877 | exit_tasks_rcu_start(); | |
878 | exit_notify(tsk, group_dead); | |
879 | proc_exit_connector(tsk); | |
880 | mpol_put_task_policy(tsk); | |
881 | #ifdef CONFIG_FUTEX | |
882 | if (unlikely(current->pi_state_cache)) | |
883 | kfree(current->pi_state_cache); | |
884 | #endif | |
885 | /* | |
886 | * Make sure we are holding no locks: | |
887 | */ | |
888 | debug_check_no_locks_held(); | |
889 | ||
890 | if (tsk->io_context) | |
891 | exit_io_context(tsk); | |
892 | ||
893 | if (tsk->splice_pipe) | |
894 | free_pipe_info(tsk->splice_pipe); | |
895 | ||
896 | if (tsk->task_frag.page) | |
897 | put_page(tsk->task_frag.page); | |
898 | ||
899 | validate_creds_for_do_exit(tsk); | |
900 | ||
901 | check_stack_usage(); | |
902 | preempt_disable(); | |
903 | if (tsk->nr_dirtied) | |
904 | __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); | |
905 | exit_rcu(); | |
906 | exit_tasks_rcu_finish(); | |
907 | ||
908 | lockdep_free_task(tsk); | |
909 | do_task_dead(); | |
910 | } | |
911 | EXPORT_SYMBOL_GPL(do_exit); | |
912 | ||
913 | void complete_and_exit(struct completion *comp, long code) | |
914 | { | |
915 | if (comp) | |
916 | complete(comp); | |
917 | ||
918 | do_exit(code); | |
919 | } | |
920 | EXPORT_SYMBOL(complete_and_exit); | |
921 | ||
922 | SYSCALL_DEFINE1(exit, int, error_code) | |
923 | { | |
924 | do_exit((error_code&0xff)<<8); | |
925 | } | |
926 | ||
927 | /* | |
928 | * Take down every thread in the group. This is called by fatal signals | |
929 | * as well as by sys_exit_group (below). | |
930 | */ | |
931 | void | |
932 | do_group_exit(int exit_code) | |
933 | { | |
934 | struct signal_struct *sig = current->signal; | |
935 | ||
936 | BUG_ON(exit_code & 0x80); /* core dumps don't get here */ | |
937 | ||
938 | if (signal_group_exit(sig)) | |
939 | exit_code = sig->group_exit_code; | |
940 | else if (!thread_group_empty(current)) { | |
941 | struct sighand_struct *const sighand = current->sighand; | |
942 | ||
943 | spin_lock_irq(&sighand->siglock); | |
944 | if (signal_group_exit(sig)) | |
945 | /* Another thread got here before we took the lock. */ | |
946 | exit_code = sig->group_exit_code; | |
947 | else { | |
948 | sig->group_exit_code = exit_code; | |
949 | sig->flags = SIGNAL_GROUP_EXIT; | |
950 | zap_other_threads(current); | |
951 | } | |
952 | spin_unlock_irq(&sighand->siglock); | |
953 | } | |
954 | ||
955 | do_exit(exit_code); | |
956 | /* NOTREACHED */ | |
957 | } | |
958 | ||
959 | /* | |
960 | * this kills every thread in the thread group. Note that any externally | |
961 | * wait4()-ing process will get the correct exit code - even if this | |
962 | * thread is not the thread group leader. | |
963 | */ | |
964 | SYSCALL_DEFINE1(exit_group, int, error_code) | |
965 | { | |
966 | do_group_exit((error_code & 0xff) << 8); | |
967 | /* NOTREACHED */ | |
968 | return 0; | |
969 | } | |
970 | ||
971 | struct waitid_info { | |
972 | pid_t pid; | |
973 | uid_t uid; | |
974 | int status; | |
975 | int cause; | |
976 | }; | |
977 | ||
978 | struct wait_opts { | |
979 | enum pid_type wo_type; | |
980 | int wo_flags; | |
981 | struct pid *wo_pid; | |
982 | ||
983 | struct waitid_info *wo_info; | |
984 | int wo_stat; | |
985 | struct rusage *wo_rusage; | |
986 | ||
987 | wait_queue_entry_t child_wait; | |
988 | int notask_error; | |
989 | }; | |
990 | ||
991 | static inline | |
992 | struct pid *task_pid_type(struct task_struct *task, enum pid_type type) | |
993 | { | |
994 | if (type != PIDTYPE_PID) | |
995 | task = task->group_leader; | |
996 | return task->pids[type].pid; | |
997 | } | |
998 | ||
999 | static int eligible_pid(struct wait_opts *wo, struct task_struct *p) | |
1000 | { | |
1001 | return wo->wo_type == PIDTYPE_MAX || | |
1002 | task_pid_type(p, wo->wo_type) == wo->wo_pid; | |
1003 | } | |
1004 | ||
1005 | static int | |
1006 | eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p) | |
1007 | { | |
1008 | if (!eligible_pid(wo, p)) | |
1009 | return 0; | |
1010 | ||
1011 | /* | |
1012 | * Wait for all children (clone and not) if __WALL is set or | |
1013 | * if it is traced by us. | |
1014 | */ | |
1015 | if (ptrace || (wo->wo_flags & __WALL)) | |
1016 | return 1; | |
1017 | ||
1018 | /* | |
1019 | * Otherwise, wait for clone children *only* if __WCLONE is set; | |
1020 | * otherwise, wait for non-clone children *only*. | |
1021 | * | |
1022 | * Note: a "clone" child here is one that reports to its parent | |
1023 | * using a signal other than SIGCHLD, or a non-leader thread which | |
1024 | * we can only see if it is traced by us. | |
1025 | */ | |
1026 | if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) | |
1027 | return 0; | |
1028 | ||
1029 | return 1; | |
1030 | } | |
1031 | ||
1032 | /* | |
1033 | * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold | |
1034 | * read_lock(&tasklist_lock) on entry. If we return zero, we still hold | |
1035 | * the lock and this task is uninteresting. If we return nonzero, we have | |
1036 | * released the lock and the system call should return. | |
1037 | */ | |
1038 | static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) | |
1039 | { | |
1040 | int state, status; | |
1041 | pid_t pid = task_pid_vnr(p); | |
1042 | uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); | |
1043 | struct waitid_info *infop; | |
1044 | ||
1045 | if (!likely(wo->wo_flags & WEXITED)) | |
1046 | return 0; | |
1047 | ||
1048 | if (unlikely(wo->wo_flags & WNOWAIT)) { | |
1049 | status = p->exit_code; | |
1050 | get_task_struct(p); | |
1051 | read_unlock(&tasklist_lock); | |
1052 | sched_annotate_sleep(); | |
1053 | if (wo->wo_rusage) | |
1054 | getrusage(p, RUSAGE_BOTH, wo->wo_rusage); | |
1055 | put_task_struct(p); | |
1056 | goto out_info; | |
1057 | } | |
1058 | /* | |
1059 | * Move the task's state to DEAD/TRACE, only one thread can do this. | |
1060 | */ | |
1061 | state = (ptrace_reparented(p) && thread_group_leader(p)) ? | |
1062 | EXIT_TRACE : EXIT_DEAD; | |
1063 | if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) | |
1064 | return 0; | |
1065 | /* | |
1066 | * We own this thread, nobody else can reap it. | |
1067 | */ | |
1068 | read_unlock(&tasklist_lock); | |
1069 | sched_annotate_sleep(); | |
1070 | ||
1071 | /* | |
1072 | * Check thread_group_leader() to exclude the traced sub-threads. | |
1073 | */ | |
1074 | if (state == EXIT_DEAD && thread_group_leader(p)) { | |
1075 | struct signal_struct *sig = p->signal; | |
1076 | struct signal_struct *psig = current->signal; | |
1077 | unsigned long maxrss; | |
1078 | u64 tgutime, tgstime; | |
1079 | ||
1080 | /* | |
1081 | * The resource counters for the group leader are in its | |
1082 | * own task_struct. Those for dead threads in the group | |
1083 | * are in its signal_struct, as are those for the child | |
1084 | * processes it has previously reaped. All these | |
1085 | * accumulate in the parent's signal_struct c* fields. | |
1086 | * | |
1087 | * We don't bother to take a lock here to protect these | |
1088 | * p->signal fields because the whole thread group is dead | |
1089 | * and nobody can change them. | |
1090 | * | |
1091 | * psig->stats_lock also protects us from our sub-theads | |
1092 | * which can reap other children at the same time. Until | |
1093 | * we change k_getrusage()-like users to rely on this lock | |
1094 | * we have to take ->siglock as well. | |
1095 | * | |
1096 | * We use thread_group_cputime_adjusted() to get times for | |
1097 | * the thread group, which consolidates times for all threads | |
1098 | * in the group including the group leader. | |
1099 | */ | |
1100 | thread_group_cputime_adjusted(p, &tgutime, &tgstime); | |
1101 | spin_lock_irq(¤t->sighand->siglock); | |
1102 | write_seqlock(&psig->stats_lock); | |
1103 | psig->cutime += tgutime + sig->cutime; | |
1104 | psig->cstime += tgstime + sig->cstime; | |
1105 | psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime; | |
1106 | psig->cmin_flt += | |
1107 | p->min_flt + sig->min_flt + sig->cmin_flt; | |
1108 | psig->cmaj_flt += | |
1109 | p->maj_flt + sig->maj_flt + sig->cmaj_flt; | |
1110 | psig->cnvcsw += | |
1111 | p->nvcsw + sig->nvcsw + sig->cnvcsw; | |
1112 | psig->cnivcsw += | |
1113 | p->nivcsw + sig->nivcsw + sig->cnivcsw; | |
1114 | psig->cinblock += | |
1115 | task_io_get_inblock(p) + | |
1116 | sig->inblock + sig->cinblock; | |
1117 | psig->coublock += | |
1118 | task_io_get_oublock(p) + | |
1119 | sig->oublock + sig->coublock; | |
1120 | maxrss = max(sig->maxrss, sig->cmaxrss); | |
1121 | if (psig->cmaxrss < maxrss) | |
1122 | psig->cmaxrss = maxrss; | |
1123 | task_io_accounting_add(&psig->ioac, &p->ioac); | |
1124 | task_io_accounting_add(&psig->ioac, &sig->ioac); | |
1125 | write_sequnlock(&psig->stats_lock); | |
1126 | spin_unlock_irq(¤t->sighand->siglock); | |
1127 | } | |
1128 | ||
1129 | if (wo->wo_rusage) | |
1130 | getrusage(p, RUSAGE_BOTH, wo->wo_rusage); | |
1131 | status = (p->signal->flags & SIGNAL_GROUP_EXIT) | |
1132 | ? p->signal->group_exit_code : p->exit_code; | |
1133 | wo->wo_stat = status; | |
1134 | ||
1135 | if (state == EXIT_TRACE) { | |
1136 | write_lock_irq(&tasklist_lock); | |
1137 | /* We dropped tasklist, ptracer could die and untrace */ | |
1138 | ptrace_unlink(p); | |
1139 | ||
1140 | /* If parent wants a zombie, don't release it now */ | |
1141 | state = EXIT_ZOMBIE; | |
1142 | if (do_notify_parent(p, p->exit_signal)) | |
1143 | state = EXIT_DEAD; | |
1144 | p->exit_state = state; | |
1145 | write_unlock_irq(&tasklist_lock); | |
1146 | } | |
1147 | if (state == EXIT_DEAD) | |
1148 | release_task(p); | |
1149 | ||
1150 | out_info: | |
1151 | infop = wo->wo_info; | |
1152 | if (infop) { | |
1153 | if ((status & 0x7f) == 0) { | |
1154 | infop->cause = CLD_EXITED; | |
1155 | infop->status = status >> 8; | |
1156 | } else { | |
1157 | infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; | |
1158 | infop->status = status & 0x7f; | |
1159 | } | |
1160 | infop->pid = pid; | |
1161 | infop->uid = uid; | |
1162 | } | |
1163 | ||
1164 | return pid; | |
1165 | } | |
1166 | ||
1167 | static int *task_stopped_code(struct task_struct *p, bool ptrace) | |
1168 | { | |
1169 | if (ptrace) { | |
1170 | if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING)) | |
1171 | return &p->exit_code; | |
1172 | } else { | |
1173 | if (p->signal->flags & SIGNAL_STOP_STOPPED) | |
1174 | return &p->signal->group_exit_code; | |
1175 | } | |
1176 | return NULL; | |
1177 | } | |
1178 | ||
1179 | /** | |
1180 | * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED | |
1181 | * @wo: wait options | |
1182 | * @ptrace: is the wait for ptrace | |
1183 | * @p: task to wait for | |
1184 | * | |
1185 | * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED. | |
1186 | * | |
1187 | * CONTEXT: | |
1188 | * read_lock(&tasklist_lock), which is released if return value is | |
1189 | * non-zero. Also, grabs and releases @p->sighand->siglock. | |
1190 | * | |
1191 | * RETURNS: | |
1192 | * 0 if wait condition didn't exist and search for other wait conditions | |
1193 | * should continue. Non-zero return, -errno on failure and @p's pid on | |
1194 | * success, implies that tasklist_lock is released and wait condition | |
1195 | * search should terminate. | |
1196 | */ | |
1197 | static int wait_task_stopped(struct wait_opts *wo, | |
1198 | int ptrace, struct task_struct *p) | |
1199 | { | |
1200 | struct waitid_info *infop; | |
1201 | int exit_code, *p_code, why; | |
1202 | uid_t uid = 0; /* unneeded, required by compiler */ | |
1203 | pid_t pid; | |
1204 | ||
1205 | /* | |
1206 | * Traditionally we see ptrace'd stopped tasks regardless of options. | |
1207 | */ | |
1208 | if (!ptrace && !(wo->wo_flags & WUNTRACED)) | |
1209 | return 0; | |
1210 | ||
1211 | if (!task_stopped_code(p, ptrace)) | |
1212 | return 0; | |
1213 | ||
1214 | exit_code = 0; | |
1215 | spin_lock_irq(&p->sighand->siglock); | |
1216 | ||
1217 | p_code = task_stopped_code(p, ptrace); | |
1218 | if (unlikely(!p_code)) | |
1219 | goto unlock_sig; | |
1220 | ||
1221 | exit_code = *p_code; | |
1222 | if (!exit_code) | |
1223 | goto unlock_sig; | |
1224 | ||
1225 | if (!unlikely(wo->wo_flags & WNOWAIT)) | |
1226 | *p_code = 0; | |
1227 | ||
1228 | uid = from_kuid_munged(current_user_ns(), task_uid(p)); | |
1229 | unlock_sig: | |
1230 | spin_unlock_irq(&p->sighand->siglock); | |
1231 | if (!exit_code) | |
1232 | return 0; | |
1233 | ||
1234 | /* | |
1235 | * Now we are pretty sure this task is interesting. | |
1236 | * Make sure it doesn't get reaped out from under us while we | |
1237 | * give up the lock and then examine it below. We don't want to | |
1238 | * keep holding onto the tasklist_lock while we call getrusage and | |
1239 | * possibly take page faults for user memory. | |
1240 | */ | |
1241 | get_task_struct(p); | |
1242 | pid = task_pid_vnr(p); | |
1243 | why = ptrace ? CLD_TRAPPED : CLD_STOPPED; | |
1244 | read_unlock(&tasklist_lock); | |
1245 | sched_annotate_sleep(); | |
1246 | if (wo->wo_rusage) | |
1247 | getrusage(p, RUSAGE_BOTH, wo->wo_rusage); | |
1248 | put_task_struct(p); | |
1249 | ||
1250 | if (likely(!(wo->wo_flags & WNOWAIT))) | |
1251 | wo->wo_stat = (exit_code << 8) | 0x7f; | |
1252 | ||
1253 | infop = wo->wo_info; | |
1254 | if (infop) { | |
1255 | infop->cause = why; | |
1256 | infop->status = exit_code; | |
1257 | infop->pid = pid; | |
1258 | infop->uid = uid; | |
1259 | } | |
1260 | return pid; | |
1261 | } | |
1262 | ||
1263 | /* | |
1264 | * Handle do_wait work for one task in a live, non-stopped state. | |
1265 | * read_lock(&tasklist_lock) on entry. If we return zero, we still hold | |
1266 | * the lock and this task is uninteresting. If we return nonzero, we have | |
1267 | * released the lock and the system call should return. | |
1268 | */ | |
1269 | static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) | |
1270 | { | |
1271 | struct waitid_info *infop; | |
1272 | pid_t pid; | |
1273 | uid_t uid; | |
1274 | ||
1275 | if (!unlikely(wo->wo_flags & WCONTINUED)) | |
1276 | return 0; | |
1277 | ||
1278 | if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) | |
1279 | return 0; | |
1280 | ||
1281 | spin_lock_irq(&p->sighand->siglock); | |
1282 | /* Re-check with the lock held. */ | |
1283 | if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { | |
1284 | spin_unlock_irq(&p->sighand->siglock); | |
1285 | return 0; | |
1286 | } | |
1287 | if (!unlikely(wo->wo_flags & WNOWAIT)) | |
1288 | p->signal->flags &= ~SIGNAL_STOP_CONTINUED; | |
1289 | uid = from_kuid_munged(current_user_ns(), task_uid(p)); | |
1290 | spin_unlock_irq(&p->sighand->siglock); | |
1291 | ||
1292 | pid = task_pid_vnr(p); | |
1293 | get_task_struct(p); | |
1294 | read_unlock(&tasklist_lock); | |
1295 | sched_annotate_sleep(); | |
1296 | if (wo->wo_rusage) | |
1297 | getrusage(p, RUSAGE_BOTH, wo->wo_rusage); | |
1298 | put_task_struct(p); | |
1299 | ||
1300 | infop = wo->wo_info; | |
1301 | if (!infop) { | |
1302 | wo->wo_stat = 0xffff; | |
1303 | } else { | |
1304 | infop->cause = CLD_CONTINUED; | |
1305 | infop->pid = pid; | |
1306 | infop->uid = uid; | |
1307 | infop->status = SIGCONT; | |
1308 | } | |
1309 | return pid; | |
1310 | } | |
1311 | ||
1312 | /* | |
1313 | * Consider @p for a wait by @parent. | |
1314 | * | |
1315 | * -ECHILD should be in ->notask_error before the first call. | |
1316 | * Returns nonzero for a final return, when we have unlocked tasklist_lock. | |
1317 | * Returns zero if the search for a child should continue; | |
1318 | * then ->notask_error is 0 if @p is an eligible child, | |
1319 | * or still -ECHILD. | |
1320 | */ | |
1321 | static int wait_consider_task(struct wait_opts *wo, int ptrace, | |
1322 | struct task_struct *p) | |
1323 | { | |
1324 | /* | |
1325 | * We can race with wait_task_zombie() from another thread. | |
1326 | * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition | |
1327 | * can't confuse the checks below. | |
1328 | */ | |
1329 | int exit_state = READ_ONCE(p->exit_state); | |
1330 | int ret; | |
1331 | ||
1332 | if (unlikely(exit_state == EXIT_DEAD)) | |
1333 | return 0; | |
1334 | ||
1335 | ret = eligible_child(wo, ptrace, p); | |
1336 | if (!ret) | |
1337 | return ret; | |
1338 | ||
1339 | if (unlikely(exit_state == EXIT_TRACE)) { | |
1340 | /* | |
1341 | * ptrace == 0 means we are the natural parent. In this case | |
1342 | * we should clear notask_error, debugger will notify us. | |
1343 | */ | |
1344 | if (likely(!ptrace)) | |
1345 | wo->notask_error = 0; | |
1346 | return 0; | |
1347 | } | |
1348 | ||
1349 | if (likely(!ptrace) && unlikely(p->ptrace)) { | |
1350 | /* | |
1351 | * If it is traced by its real parent's group, just pretend | |
1352 | * the caller is ptrace_do_wait() and reap this child if it | |
1353 | * is zombie. | |
1354 | * | |
1355 | * This also hides group stop state from real parent; otherwise | |
1356 | * a single stop can be reported twice as group and ptrace stop. | |
1357 | * If a ptracer wants to distinguish these two events for its | |
1358 | * own children it should create a separate process which takes | |
1359 | * the role of real parent. | |
1360 | */ | |
1361 | if (!ptrace_reparented(p)) | |
1362 | ptrace = 1; | |
1363 | } | |
1364 | ||
1365 | /* slay zombie? */ | |
1366 | if (exit_state == EXIT_ZOMBIE) { | |
1367 | /* we don't reap group leaders with subthreads */ | |
1368 | if (!delay_group_leader(p)) { | |
1369 | /* | |
1370 | * A zombie ptracee is only visible to its ptracer. | |
1371 | * Notification and reaping will be cascaded to the | |
1372 | * real parent when the ptracer detaches. | |
1373 | */ | |
1374 | if (unlikely(ptrace) || likely(!p->ptrace)) | |
1375 | return wait_task_zombie(wo, p); | |
1376 | } | |
1377 | ||
1378 | /* | |
1379 | * Allow access to stopped/continued state via zombie by | |
1380 | * falling through. Clearing of notask_error is complex. | |
1381 | * | |
1382 | * When !@ptrace: | |
1383 | * | |
1384 | * If WEXITED is set, notask_error should naturally be | |
1385 | * cleared. If not, subset of WSTOPPED|WCONTINUED is set, | |
1386 | * so, if there are live subthreads, there are events to | |
1387 | * wait for. If all subthreads are dead, it's still safe | |
1388 | * to clear - this function will be called again in finite | |
1389 | * amount time once all the subthreads are released and | |
1390 | * will then return without clearing. | |
1391 | * | |
1392 | * When @ptrace: | |
1393 | * | |
1394 | * Stopped state is per-task and thus can't change once the | |
1395 | * target task dies. Only continued and exited can happen. | |
1396 | * Clear notask_error if WCONTINUED | WEXITED. | |
1397 | */ | |
1398 | if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED))) | |
1399 | wo->notask_error = 0; | |
1400 | } else { | |
1401 | /* | |
1402 | * @p is alive and it's gonna stop, continue or exit, so | |
1403 | * there always is something to wait for. | |
1404 | */ | |
1405 | wo->notask_error = 0; | |
1406 | } | |
1407 | ||
1408 | /* | |
1409 | * Wait for stopped. Depending on @ptrace, different stopped state | |
1410 | * is used and the two don't interact with each other. | |
1411 | */ | |
1412 | ret = wait_task_stopped(wo, ptrace, p); | |
1413 | if (ret) | |
1414 | return ret; | |
1415 | ||
1416 | /* | |
1417 | * Wait for continued. There's only one continued state and the | |
1418 | * ptracer can consume it which can confuse the real parent. Don't | |
1419 | * use WCONTINUED from ptracer. You don't need or want it. | |
1420 | */ | |
1421 | return wait_task_continued(wo, p); | |
1422 | } | |
1423 | ||
1424 | /* | |
1425 | * Do the work of do_wait() for one thread in the group, @tsk. | |
1426 | * | |
1427 | * -ECHILD should be in ->notask_error before the first call. | |
1428 | * Returns nonzero for a final return, when we have unlocked tasklist_lock. | |
1429 | * Returns zero if the search for a child should continue; then | |
1430 | * ->notask_error is 0 if there were any eligible children, | |
1431 | * or still -ECHILD. | |
1432 | */ | |
1433 | static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) | |
1434 | { | |
1435 | struct task_struct *p; | |
1436 | ||
1437 | list_for_each_entry(p, &tsk->children, sibling) { | |
1438 | int ret = wait_consider_task(wo, 0, p); | |
1439 | ||
1440 | if (ret) | |
1441 | return ret; | |
1442 | } | |
1443 | ||
1444 | return 0; | |
1445 | } | |
1446 | ||
1447 | static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) | |
1448 | { | |
1449 | struct task_struct *p; | |
1450 | ||
1451 | list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { | |
1452 | int ret = wait_consider_task(wo, 1, p); | |
1453 | ||
1454 | if (ret) | |
1455 | return ret; | |
1456 | } | |
1457 | ||
1458 | return 0; | |
1459 | } | |
1460 | ||
1461 | static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode, | |
1462 | int sync, void *key) | |
1463 | { | |
1464 | struct wait_opts *wo = container_of(wait, struct wait_opts, | |
1465 | child_wait); | |
1466 | struct task_struct *p = key; | |
1467 | ||
1468 | if (!eligible_pid(wo, p)) | |
1469 | return 0; | |
1470 | ||
1471 | if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) | |
1472 | return 0; | |
1473 | ||
1474 | return default_wake_function(wait, mode, sync, key); | |
1475 | } | |
1476 | ||
1477 | void __wake_up_parent(struct task_struct *p, struct task_struct *parent) | |
1478 | { | |
1479 | __wake_up_sync_key(&parent->signal->wait_chldexit, | |
1480 | TASK_INTERRUPTIBLE, 1, p); | |
1481 | } | |
1482 | ||
1483 | static long do_wait(struct wait_opts *wo) | |
1484 | { | |
1485 | struct task_struct *tsk; | |
1486 | int retval; | |
1487 | ||
1488 | trace_sched_process_wait(wo->wo_pid); | |
1489 | ||
1490 | init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); | |
1491 | wo->child_wait.private = current; | |
1492 | add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); | |
1493 | repeat: | |
1494 | /* | |
1495 | * If there is nothing that can match our criteria, just get out. | |
1496 | * We will clear ->notask_error to zero if we see any child that | |
1497 | * might later match our criteria, even if we are not able to reap | |
1498 | * it yet. | |
1499 | */ | |
1500 | wo->notask_error = -ECHILD; | |
1501 | if ((wo->wo_type < PIDTYPE_MAX) && | |
1502 | (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type]))) | |
1503 | goto notask; | |
1504 | ||
1505 | set_current_state(TASK_INTERRUPTIBLE); | |
1506 | read_lock(&tasklist_lock); | |
1507 | tsk = current; | |
1508 | do { | |
1509 | retval = do_wait_thread(wo, tsk); | |
1510 | if (retval) | |
1511 | goto end; | |
1512 | ||
1513 | retval = ptrace_do_wait(wo, tsk); | |
1514 | if (retval) | |
1515 | goto end; | |
1516 | ||
1517 | if (wo->wo_flags & __WNOTHREAD) | |
1518 | break; | |
1519 | } while_each_thread(current, tsk); | |
1520 | read_unlock(&tasklist_lock); | |
1521 | ||
1522 | notask: | |
1523 | retval = wo->notask_error; | |
1524 | if (!retval && !(wo->wo_flags & WNOHANG)) { | |
1525 | retval = -ERESTARTSYS; | |
1526 | if (!signal_pending(current)) { | |
1527 | schedule(); | |
1528 | goto repeat; | |
1529 | } | |
1530 | } | |
1531 | end: | |
1532 | __set_current_state(TASK_RUNNING); | |
1533 | remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); | |
1534 | return retval; | |
1535 | } | |
1536 | ||
1537 | static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, | |
1538 | int options, struct rusage *ru) | |
1539 | { | |
1540 | struct wait_opts wo; | |
1541 | struct pid *pid = NULL; | |
1542 | enum pid_type type; | |
1543 | long ret; | |
1544 | ||
1545 | if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED| | |
1546 | __WNOTHREAD|__WCLONE|__WALL)) | |
1547 | return -EINVAL; | |
1548 | if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) | |
1549 | return -EINVAL; | |
1550 | ||
1551 | switch (which) { | |
1552 | case P_ALL: | |
1553 | type = PIDTYPE_MAX; | |
1554 | break; | |
1555 | case P_PID: | |
1556 | type = PIDTYPE_PID; | |
1557 | if (upid <= 0) | |
1558 | return -EINVAL; | |
1559 | break; | |
1560 | case P_PGID: | |
1561 | type = PIDTYPE_PGID; | |
1562 | if (upid <= 0) | |
1563 | return -EINVAL; | |
1564 | break; | |
1565 | default: | |
1566 | return -EINVAL; | |
1567 | } | |
1568 | ||
1569 | if (type < PIDTYPE_MAX) | |
1570 | pid = find_get_pid(upid); | |
1571 | ||
1572 | wo.wo_type = type; | |
1573 | wo.wo_pid = pid; | |
1574 | wo.wo_flags = options; | |
1575 | wo.wo_info = infop; | |
1576 | wo.wo_rusage = ru; | |
1577 | ret = do_wait(&wo); | |
1578 | ||
1579 | put_pid(pid); | |
1580 | return ret; | |
1581 | } | |
1582 | ||
1583 | SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, | |
1584 | infop, int, options, struct rusage __user *, ru) | |
1585 | { | |
1586 | struct rusage r; | |
1587 | struct waitid_info info = {.status = 0}; | |
1588 | long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL); | |
1589 | int signo = 0; | |
1590 | ||
1591 | if (err > 0) { | |
1592 | signo = SIGCHLD; | |
1593 | err = 0; | |
1594 | if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) | |
1595 | return -EFAULT; | |
1596 | } | |
1597 | if (!infop) | |
1598 | return err; | |
1599 | ||
1600 | if (!access_ok(VERIFY_WRITE, infop, sizeof(*infop))) | |
1601 | return -EFAULT; | |
1602 | ||
1603 | user_access_begin(); | |
1604 | unsafe_put_user(signo, &infop->si_signo, Efault); | |
1605 | unsafe_put_user(0, &infop->si_errno, Efault); | |
1606 | unsafe_put_user(info.cause, &infop->si_code, Efault); | |
1607 | unsafe_put_user(info.pid, &infop->si_pid, Efault); | |
1608 | unsafe_put_user(info.uid, &infop->si_uid, Efault); | |
1609 | unsafe_put_user(info.status, &infop->si_status, Efault); | |
1610 | user_access_end(); | |
1611 | return err; | |
1612 | Efault: | |
1613 | user_access_end(); | |
1614 | return -EFAULT; | |
1615 | } | |
1616 | ||
1617 | long kernel_wait4(pid_t upid, int __user *stat_addr, int options, | |
1618 | struct rusage *ru) | |
1619 | { | |
1620 | struct wait_opts wo; | |
1621 | struct pid *pid = NULL; | |
1622 | enum pid_type type; | |
1623 | long ret; | |
1624 | ||
1625 | if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| | |
1626 | __WNOTHREAD|__WCLONE|__WALL)) | |
1627 | return -EINVAL; | |
1628 | ||
1629 | /* -INT_MIN is not defined */ | |
1630 | if (upid == INT_MIN) | |
1631 | return -ESRCH; | |
1632 | ||
1633 | if (upid == -1) | |
1634 | type = PIDTYPE_MAX; | |
1635 | else if (upid < 0) { | |
1636 | type = PIDTYPE_PGID; | |
1637 | pid = find_get_pid(-upid); | |
1638 | } else if (upid == 0) { | |
1639 | type = PIDTYPE_PGID; | |
1640 | pid = get_task_pid(current, PIDTYPE_PGID); | |
1641 | } else /* upid > 0 */ { | |
1642 | type = PIDTYPE_PID; | |
1643 | pid = find_get_pid(upid); | |
1644 | } | |
1645 | ||
1646 | wo.wo_type = type; | |
1647 | wo.wo_pid = pid; | |
1648 | wo.wo_flags = options | WEXITED; | |
1649 | wo.wo_info = NULL; | |
1650 | wo.wo_stat = 0; | |
1651 | wo.wo_rusage = ru; | |
1652 | ret = do_wait(&wo); | |
1653 | put_pid(pid); | |
1654 | if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr)) | |
1655 | ret = -EFAULT; | |
1656 | ||
1657 | return ret; | |
1658 | } | |
1659 | ||
1660 | SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, | |
1661 | int, options, struct rusage __user *, ru) | |
1662 | { | |
1663 | struct rusage r; | |
1664 | long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL); | |
1665 | ||
1666 | if (err > 0) { | |
1667 | if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) | |
1668 | return -EFAULT; | |
1669 | } | |
1670 | return err; | |
1671 | } | |
1672 | ||
1673 | #ifdef __ARCH_WANT_SYS_WAITPID | |
1674 | ||
1675 | /* | |
1676 | * sys_waitpid() remains for compatibility. waitpid() should be | |
1677 | * implemented by calling sys_wait4() from libc.a. | |
1678 | */ | |
1679 | SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) | |
1680 | { | |
1681 | return sys_wait4(pid, stat_addr, options, NULL); | |
1682 | } | |
1683 | ||
1684 | #endif | |
1685 | ||
1686 | #ifdef CONFIG_COMPAT | |
1687 | COMPAT_SYSCALL_DEFINE4(wait4, | |
1688 | compat_pid_t, pid, | |
1689 | compat_uint_t __user *, stat_addr, | |
1690 | int, options, | |
1691 | struct compat_rusage __user *, ru) | |
1692 | { | |
1693 | struct rusage r; | |
1694 | long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL); | |
1695 | if (err > 0) { | |
1696 | if (ru && put_compat_rusage(&r, ru)) | |
1697 | return -EFAULT; | |
1698 | } | |
1699 | return err; | |
1700 | } | |
1701 | ||
1702 | COMPAT_SYSCALL_DEFINE5(waitid, | |
1703 | int, which, compat_pid_t, pid, | |
1704 | struct compat_siginfo __user *, infop, int, options, | |
1705 | struct compat_rusage __user *, uru) | |
1706 | { | |
1707 | struct rusage ru; | |
1708 | struct waitid_info info = {.status = 0}; | |
1709 | long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL); | |
1710 | int signo = 0; | |
1711 | if (err > 0) { | |
1712 | signo = SIGCHLD; | |
1713 | err = 0; | |
1714 | if (uru) { | |
1715 | /* kernel_waitid() overwrites everything in ru */ | |
1716 | if (COMPAT_USE_64BIT_TIME) | |
1717 | err = copy_to_user(uru, &ru, sizeof(ru)); | |
1718 | else | |
1719 | err = put_compat_rusage(&ru, uru); | |
1720 | if (err) | |
1721 | return -EFAULT; | |
1722 | } | |
1723 | } | |
1724 | ||
1725 | if (!infop) | |
1726 | return err; | |
1727 | ||
1728 | if (!access_ok(VERIFY_WRITE, infop, sizeof(*infop))) | |
1729 | return -EFAULT; | |
1730 | ||
1731 | user_access_begin(); | |
1732 | unsafe_put_user(signo, &infop->si_signo, Efault); | |
1733 | unsafe_put_user(0, &infop->si_errno, Efault); | |
1734 | unsafe_put_user(info.cause, &infop->si_code, Efault); | |
1735 | unsafe_put_user(info.pid, &infop->si_pid, Efault); | |
1736 | unsafe_put_user(info.uid, &infop->si_uid, Efault); | |
1737 | unsafe_put_user(info.status, &infop->si_status, Efault); | |
1738 | user_access_end(); | |
1739 | return err; | |
1740 | Efault: | |
1741 | user_access_end(); | |
1742 | return -EFAULT; | |
1743 | } | |
1744 | #endif | |
1745 | ||
1746 | __weak void abort(void) | |
1747 | { | |
1748 | BUG(); | |
1749 | ||
1750 | /* if that doesn't kill us, halt */ | |
1751 | panic("Oops failed to kill thread"); | |
1752 | } | |
1753 | EXPORT_SYMBOL(abort); |