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