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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 exit_mm(struct task_struct * tsk); |
63 | |
64 | static void __unhash_process(struct task_struct *p, bool group_dead) |
65 | { |
66 | nr_threads--; |
67 | detach_pid(p, PIDTYPE_PID); |
68 | if (group_dead) { |
69 | detach_pid(p, PIDTYPE_PGID); |
70 | detach_pid(p, PIDTYPE_SID); |
71 | |
72 | list_del_rcu(&p->tasks); |
73 | list_del_init(&p->sibling); |
74 | __this_cpu_dec(process_counts); |
75 | } |
76 | list_del_rcu(&p->thread_group); |
77 | list_del_rcu(&p->thread_node); |
78 | } |
79 | |
80 | /* |
81 | * This function expects the tasklist_lock write-locked. |
82 | */ |
83 | static void __exit_signal(struct task_struct *tsk) |
84 | { |
85 | struct signal_struct *sig = tsk->signal; |
86 | bool group_dead = thread_group_leader(tsk); |
87 | struct sighand_struct *sighand; |
88 | struct tty_struct *uninitialized_var(tty); |
89 | cputime_t utime, stime; |
90 | |
91 | sighand = rcu_dereference_check(tsk->sighand, |
92 | lockdep_tasklist_lock_is_held()); |
93 | spin_lock(&sighand->siglock); |
94 | |
95 | posix_cpu_timers_exit(tsk); |
96 | if (group_dead) { |
97 | posix_cpu_timers_exit_group(tsk); |
98 | tty = sig->tty; |
99 | sig->tty = NULL; |
100 | } else { |
101 | /* |
102 | * This can only happen if the caller is de_thread(). |
103 | * FIXME: this is the temporary hack, we should teach |
104 | * posix-cpu-timers to handle this case correctly. |
105 | */ |
106 | if (unlikely(has_group_leader_pid(tsk))) |
107 | posix_cpu_timers_exit_group(tsk); |
108 | |
109 | /* |
110 | * If there is any task waiting for the group exit |
111 | * then notify it: |
112 | */ |
113 | if (sig->notify_count > 0 && !--sig->notify_count) |
114 | wake_up_process(sig->group_exit_task); |
115 | |
116 | if (tsk == sig->curr_target) |
117 | sig->curr_target = next_thread(tsk); |
118 | /* |
119 | * Accumulate here the counters for all threads but the |
120 | * group leader as they die, so they can be added into |
121 | * the process-wide totals when those are taken. |
122 | * The group leader stays around as a zombie as long |
123 | * as there are other threads. When it gets reaped, |
124 | * the exit.c code will add its counts into these totals. |
125 | * We won't ever get here for the group leader, since it |
126 | * will have been the last reference on the signal_struct. |
127 | */ |
128 | task_cputime(tsk, &utime, &stime); |
129 | sig->utime += utime; |
130 | sig->stime += stime; |
131 | sig->gtime += task_gtime(tsk); |
132 | sig->min_flt += tsk->min_flt; |
133 | sig->maj_flt += tsk->maj_flt; |
134 | sig->nvcsw += tsk->nvcsw; |
135 | sig->nivcsw += tsk->nivcsw; |
136 | sig->inblock += task_io_get_inblock(tsk); |
137 | sig->oublock += task_io_get_oublock(tsk); |
138 | task_io_accounting_add(&sig->ioac, &tsk->ioac); |
139 | sig->sum_sched_runtime += tsk->se.sum_exec_runtime; |
140 | } |
141 | |
142 | sig->nr_threads--; |
143 | __unhash_process(tsk, group_dead); |
144 | |
145 | /* |
146 | * Do this under ->siglock, we can race with another thread |
147 | * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. |
148 | */ |
149 | flush_sigqueue(&tsk->pending); |
150 | tsk->sighand = NULL; |
151 | spin_unlock(&sighand->siglock); |
152 | |
153 | __cleanup_sighand(sighand); |
154 | clear_tsk_thread_flag(tsk,TIF_SIGPENDING); |
155 | if (group_dead) { |
156 | flush_sigqueue(&sig->shared_pending); |
157 | tty_kref_put(tty); |
158 | } |
159 | } |
160 | |
161 | static void delayed_put_task_struct(struct rcu_head *rhp) |
162 | { |
163 | struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); |
164 | |
165 | perf_event_delayed_put(tsk); |
166 | trace_sched_process_free(tsk); |
167 | put_task_struct(tsk); |
168 | } |
169 | |
170 | |
171 | void release_task(struct task_struct * p) |
172 | { |
173 | struct task_struct *leader; |
174 | int zap_leader; |
175 | repeat: |
176 | /* don't need to get the RCU readlock here - the process is dead and |
177 | * can't be modifying its own credentials. But shut RCU-lockdep up */ |
178 | rcu_read_lock(); |
179 | atomic_dec(&__task_cred(p)->user->processes); |
180 | rcu_read_unlock(); |
181 | |
182 | proc_flush_task(p); |
183 | |
184 | write_lock_irq(&tasklist_lock); |
185 | ptrace_release_task(p); |
186 | __exit_signal(p); |
187 | |
188 | /* |
189 | * If we are the last non-leader member of the thread |
190 | * group, and the leader is zombie, then notify the |
191 | * group leader's parent process. (if it wants notification.) |
192 | */ |
193 | zap_leader = 0; |
194 | leader = p->group_leader; |
195 | if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) { |
196 | /* |
197 | * If we were the last child thread and the leader has |
198 | * exited already, and the leader's parent ignores SIGCHLD, |
199 | * then we are the one who should release the leader. |
200 | */ |
201 | zap_leader = do_notify_parent(leader, leader->exit_signal); |
202 | if (zap_leader) |
203 | leader->exit_state = EXIT_DEAD; |
204 | } |
205 | |
206 | write_unlock_irq(&tasklist_lock); |
207 | release_thread(p); |
208 | call_rcu(&p->rcu, delayed_put_task_struct); |
209 | |
210 | p = leader; |
211 | if (unlikely(zap_leader)) |
212 | goto repeat; |
213 | } |
214 | |
215 | /* |
216 | * This checks not only the pgrp, but falls back on the pid if no |
217 | * satisfactory pgrp is found. I dunno - gdb doesn't work correctly |
218 | * without this... |
219 | * |
220 | * The caller must hold rcu lock or the tasklist lock. |
221 | */ |
222 | struct pid *session_of_pgrp(struct pid *pgrp) |
223 | { |
224 | struct task_struct *p; |
225 | struct pid *sid = NULL; |
226 | |
227 | p = pid_task(pgrp, PIDTYPE_PGID); |
228 | if (p == NULL) |
229 | p = pid_task(pgrp, PIDTYPE_PID); |
230 | if (p != NULL) |
231 | sid = task_session(p); |
232 | |
233 | return sid; |
234 | } |
235 | |
236 | /* |
237 | * Determine if a process group is "orphaned", according to the POSIX |
238 | * definition in 2.2.2.52. Orphaned process groups are not to be affected |
239 | * by terminal-generated stop signals. Newly orphaned process groups are |
240 | * to receive a SIGHUP and a SIGCONT. |
241 | * |
242 | * "I ask you, have you ever known what it is to be an orphan?" |
243 | */ |
244 | static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task) |
245 | { |
246 | struct task_struct *p; |
247 | |
248 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
249 | if ((p == ignored_task) || |
250 | (p->exit_state && thread_group_empty(p)) || |
251 | is_global_init(p->real_parent)) |
252 | continue; |
253 | |
254 | if (task_pgrp(p->real_parent) != pgrp && |
255 | task_session(p->real_parent) == task_session(p)) |
256 | return 0; |
257 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
258 | |
259 | return 1; |
260 | } |
261 | |
262 | int is_current_pgrp_orphaned(void) |
263 | { |
264 | int retval; |
265 | |
266 | read_lock(&tasklist_lock); |
267 | retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); |
268 | read_unlock(&tasklist_lock); |
269 | |
270 | return retval; |
271 | } |
272 | |
273 | static bool has_stopped_jobs(struct pid *pgrp) |
274 | { |
275 | struct task_struct *p; |
276 | |
277 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
278 | if (p->signal->flags & SIGNAL_STOP_STOPPED) |
279 | return true; |
280 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
281 | |
282 | return false; |
283 | } |
284 | |
285 | /* |
286 | * Check to see if any process groups have become orphaned as |
287 | * a result of our exiting, and if they have any stopped jobs, |
288 | * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) |
289 | */ |
290 | static void |
291 | kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) |
292 | { |
293 | struct pid *pgrp = task_pgrp(tsk); |
294 | struct task_struct *ignored_task = tsk; |
295 | |
296 | if (!parent) |
297 | /* exit: our father is in a different pgrp than |
298 | * we are and we were the only connection outside. |
299 | */ |
300 | parent = tsk->real_parent; |
301 | else |
302 | /* reparent: our child is in a different pgrp than |
303 | * we are, and it was the only connection outside. |
304 | */ |
305 | ignored_task = NULL; |
306 | |
307 | if (task_pgrp(parent) != pgrp && |
308 | task_session(parent) == task_session(tsk) && |
309 | will_become_orphaned_pgrp(pgrp, ignored_task) && |
310 | has_stopped_jobs(pgrp)) { |
311 | __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); |
312 | __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); |
313 | } |
314 | } |
315 | |
316 | /* |
317 | * Let kernel threads use this to say that they allow a certain signal. |
318 | * Must not be used if kthread was cloned with CLONE_SIGHAND. |
319 | */ |
320 | int allow_signal(int sig) |
321 | { |
322 | if (!valid_signal(sig) || sig < 1) |
323 | return -EINVAL; |
324 | |
325 | spin_lock_irq(¤t->sighand->siglock); |
326 | /* This is only needed for daemonize()'ed kthreads */ |
327 | sigdelset(¤t->blocked, sig); |
328 | /* |
329 | * Kernel threads handle their own signals. Let the signal code |
330 | * know it'll be handled, so that they don't get converted to |
331 | * SIGKILL or just silently dropped. |
332 | */ |
333 | current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2; |
334 | recalc_sigpending(); |
335 | spin_unlock_irq(¤t->sighand->siglock); |
336 | return 0; |
337 | } |
338 | |
339 | EXPORT_SYMBOL(allow_signal); |
340 | |
341 | int disallow_signal(int sig) |
342 | { |
343 | if (!valid_signal(sig) || sig < 1) |
344 | return -EINVAL; |
345 | |
346 | spin_lock_irq(¤t->sighand->siglock); |
347 | current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN; |
348 | recalc_sigpending(); |
349 | spin_unlock_irq(¤t->sighand->siglock); |
350 | return 0; |
351 | } |
352 | |
353 | EXPORT_SYMBOL(disallow_signal); |
354 | |
355 | #ifdef CONFIG_MM_OWNER |
356 | /* |
357 | * A task is exiting. If it owned this mm, find a new owner for the mm. |
358 | */ |
359 | void mm_update_next_owner(struct mm_struct *mm) |
360 | { |
361 | struct task_struct *c, *g, *p = current; |
362 | |
363 | retry: |
364 | /* |
365 | * If the exiting or execing task is not the owner, it's |
366 | * someone else's problem. |
367 | */ |
368 | if (mm->owner != p) |
369 | return; |
370 | /* |
371 | * The current owner is exiting/execing and there are no other |
372 | * candidates. Do not leave the mm pointing to a possibly |
373 | * freed task structure. |
374 | */ |
375 | if (atomic_read(&mm->mm_users) <= 1) { |
376 | mm->owner = NULL; |
377 | return; |
378 | } |
379 | |
380 | read_lock(&tasklist_lock); |
381 | /* |
382 | * Search in the children |
383 | */ |
384 | list_for_each_entry(c, &p->children, sibling) { |
385 | if (c->mm == mm) |
386 | goto assign_new_owner; |
387 | } |
388 | |
389 | /* |
390 | * Search in the siblings |
391 | */ |
392 | list_for_each_entry(c, &p->real_parent->children, sibling) { |
393 | if (c->mm == mm) |
394 | goto assign_new_owner; |
395 | } |
396 | |
397 | /* |
398 | * Search through everything else. We should not get |
399 | * here often |
400 | */ |
401 | do_each_thread(g, c) { |
402 | if (c->mm == mm) |
403 | goto assign_new_owner; |
404 | } while_each_thread(g, c); |
405 | |
406 | read_unlock(&tasklist_lock); |
407 | /* |
408 | * We found no owner yet mm_users > 1: this implies that we are |
409 | * most likely racing with swapoff (try_to_unuse()) or /proc or |
410 | * ptrace or page migration (get_task_mm()). Mark owner as NULL. |
411 | */ |
412 | mm->owner = NULL; |
413 | return; |
414 | |
415 | assign_new_owner: |
416 | BUG_ON(c == p); |
417 | get_task_struct(c); |
418 | /* |
419 | * The task_lock protects c->mm from changing. |
420 | * We always want mm->owner->mm == mm |
421 | */ |
422 | task_lock(c); |
423 | /* |
424 | * Delay read_unlock() till we have the task_lock() |
425 | * to ensure that c does not slip away underneath us |
426 | */ |
427 | read_unlock(&tasklist_lock); |
428 | if (c->mm != mm) { |
429 | task_unlock(c); |
430 | put_task_struct(c); |
431 | goto retry; |
432 | } |
433 | mm->owner = c; |
434 | task_unlock(c); |
435 | put_task_struct(c); |
436 | } |
437 | #endif /* CONFIG_MM_OWNER */ |
438 | |
439 | /* |
440 | * Turn us into a lazy TLB process if we |
441 | * aren't already.. |
442 | */ |
443 | static void exit_mm(struct task_struct * tsk) |
444 | { |
445 | struct mm_struct *mm = tsk->mm; |
446 | struct core_state *core_state; |
447 | |
448 | mm_release(tsk, mm); |
449 | if (!mm) |
450 | return; |
451 | sync_mm_rss(mm); |
452 | /* |
453 | * Serialize with any possible pending coredump. |
454 | * We must hold mmap_sem around checking core_state |
455 | * and clearing tsk->mm. The core-inducing thread |
456 | * will increment ->nr_threads for each thread in the |
457 | * group with ->mm != NULL. |
458 | */ |
459 | down_read(&mm->mmap_sem); |
460 | core_state = mm->core_state; |
461 | if (core_state) { |
462 | struct core_thread self; |
463 | up_read(&mm->mmap_sem); |
464 | |
465 | self.task = tsk; |
466 | self.next = xchg(&core_state->dumper.next, &self); |
467 | /* |
468 | * Implies mb(), the result of xchg() must be visible |
469 | * to core_state->dumper. |
470 | */ |
471 | if (atomic_dec_and_test(&core_state->nr_threads)) |
472 | complete(&core_state->startup); |
473 | |
474 | for (;;) { |
475 | set_task_state(tsk, TASK_UNINTERRUPTIBLE); |
476 | if (!self.task) /* see coredump_finish() */ |
477 | break; |
478 | freezable_schedule(); |
479 | } |
480 | __set_task_state(tsk, TASK_RUNNING); |
481 | down_read(&mm->mmap_sem); |
482 | } |
483 | atomic_inc(&mm->mm_count); |
484 | BUG_ON(mm != tsk->active_mm); |
485 | /* more a memory barrier than a real lock */ |
486 | task_lock(tsk); |
487 | tsk->mm = NULL; |
488 | up_read(&mm->mmap_sem); |
489 | enter_lazy_tlb(mm, current); |
490 | task_unlock(tsk); |
491 | mm_update_next_owner(mm); |
492 | mmput(mm); |
493 | } |
494 | |
495 | /* |
496 | * When we die, we re-parent all our children, and try to: |
497 | * 1. give them to another thread in our thread group, if such a member exists |
498 | * 2. give it to the first ancestor process which prctl'd itself as a |
499 | * child_subreaper for its children (like a service manager) |
500 | * 3. give it to the init process (PID 1) in our pid namespace |
501 | */ |
502 | static struct task_struct *find_new_reaper(struct task_struct *father) |
503 | __releases(&tasklist_lock) |
504 | __acquires(&tasklist_lock) |
505 | { |
506 | struct pid_namespace *pid_ns = task_active_pid_ns(father); |
507 | struct task_struct *thread; |
508 | |
509 | thread = father; |
510 | while_each_thread(father, thread) { |
511 | if (thread->flags & PF_EXITING) |
512 | continue; |
513 | if (unlikely(pid_ns->child_reaper == father)) |
514 | pid_ns->child_reaper = thread; |
515 | return thread; |
516 | } |
517 | |
518 | if (unlikely(pid_ns->child_reaper == father)) { |
519 | write_unlock_irq(&tasklist_lock); |
520 | if (unlikely(pid_ns == &init_pid_ns)) { |
521 | panic("Attempted to kill init! exitcode=0x%08x\n", |
522 | father->signal->group_exit_code ?: |
523 | father->exit_code); |
524 | } |
525 | |
526 | zap_pid_ns_processes(pid_ns); |
527 | write_lock_irq(&tasklist_lock); |
528 | } else if (father->signal->has_child_subreaper) { |
529 | struct task_struct *reaper; |
530 | |
531 | /* |
532 | * Find the first ancestor marked as child_subreaper. |
533 | * Note that the code below checks same_thread_group(reaper, |
534 | * pid_ns->child_reaper). This is what we need to DTRT in a |
535 | * PID namespace. However we still need the check above, see |
536 | * http://marc.info/?l=linux-kernel&m=131385460420380 |
537 | */ |
538 | for (reaper = father->real_parent; |
539 | reaper != &init_task; |
540 | reaper = reaper->real_parent) { |
541 | if (same_thread_group(reaper, pid_ns->child_reaper)) |
542 | break; |
543 | if (!reaper->signal->is_child_subreaper) |
544 | continue; |
545 | thread = reaper; |
546 | do { |
547 | if (!(thread->flags & PF_EXITING)) |
548 | return reaper; |
549 | } while_each_thread(reaper, thread); |
550 | } |
551 | } |
552 | |
553 | return pid_ns->child_reaper; |
554 | } |
555 | |
556 | /* |
557 | * Any that need to be release_task'd are put on the @dead list. |
558 | */ |
559 | static void reparent_leader(struct task_struct *father, struct task_struct *p, |
560 | struct list_head *dead) |
561 | { |
562 | list_move_tail(&p->sibling, &p->real_parent->children); |
563 | |
564 | if (p->exit_state == EXIT_DEAD) |
565 | return; |
566 | /* |
567 | * If this is a threaded reparent there is no need to |
568 | * notify anyone anything has happened. |
569 | */ |
570 | if (same_thread_group(p->real_parent, father)) |
571 | return; |
572 | |
573 | /* We don't want people slaying init. */ |
574 | p->exit_signal = SIGCHLD; |
575 | |
576 | /* If it has exited notify the new parent about this child's death. */ |
577 | if (!p->ptrace && |
578 | p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { |
579 | if (do_notify_parent(p, p->exit_signal)) { |
580 | p->exit_state = EXIT_DEAD; |
581 | list_move_tail(&p->sibling, dead); |
582 | } |
583 | } |
584 | |
585 | kill_orphaned_pgrp(p, father); |
586 | } |
587 | |
588 | static void forget_original_parent(struct task_struct *father) |
589 | { |
590 | struct task_struct *p, *n, *reaper; |
591 | LIST_HEAD(dead_children); |
592 | |
593 | write_lock_irq(&tasklist_lock); |
594 | /* |
595 | * Note that exit_ptrace() and find_new_reaper() might |
596 | * drop tasklist_lock and reacquire it. |
597 | */ |
598 | exit_ptrace(father); |
599 | reaper = find_new_reaper(father); |
600 | |
601 | list_for_each_entry_safe(p, n, &father->children, sibling) { |
602 | struct task_struct *t = p; |
603 | do { |
604 | t->real_parent = reaper; |
605 | if (t->parent == father) { |
606 | BUG_ON(t->ptrace); |
607 | t->parent = t->real_parent; |
608 | } |
609 | if (t->pdeath_signal) |
610 | group_send_sig_info(t->pdeath_signal, |
611 | SEND_SIG_NOINFO, t); |
612 | } while_each_thread(p, t); |
613 | reparent_leader(father, p, &dead_children); |
614 | } |
615 | write_unlock_irq(&tasklist_lock); |
616 | |
617 | BUG_ON(!list_empty(&father->children)); |
618 | |
619 | list_for_each_entry_safe(p, n, &dead_children, sibling) { |
620 | list_del_init(&p->sibling); |
621 | release_task(p); |
622 | } |
623 | } |
624 | |
625 | /* |
626 | * Send signals to all our closest relatives so that they know |
627 | * to properly mourn us.. |
628 | */ |
629 | static void exit_notify(struct task_struct *tsk, int group_dead) |
630 | { |
631 | bool autoreap; |
632 | |
633 | /* |
634 | * This does two things: |
635 | * |
636 | * A. Make init inherit all the child processes |
637 | * B. Check to see if any process groups have become orphaned |
638 | * as a result of our exiting, and if they have any stopped |
639 | * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) |
640 | */ |
641 | forget_original_parent(tsk); |
642 | |
643 | write_lock_irq(&tasklist_lock); |
644 | if (group_dead) |
645 | kill_orphaned_pgrp(tsk->group_leader, NULL); |
646 | |
647 | if (unlikely(tsk->ptrace)) { |
648 | int sig = thread_group_leader(tsk) && |
649 | thread_group_empty(tsk) && |
650 | !ptrace_reparented(tsk) ? |
651 | tsk->exit_signal : SIGCHLD; |
652 | autoreap = do_notify_parent(tsk, sig); |
653 | } else if (thread_group_leader(tsk)) { |
654 | autoreap = thread_group_empty(tsk) && |
655 | do_notify_parent(tsk, tsk->exit_signal); |
656 | } else { |
657 | autoreap = true; |
658 | } |
659 | |
660 | tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE; |
661 | |
662 | /* mt-exec, de_thread() is waiting for group leader */ |
663 | if (unlikely(tsk->signal->notify_count < 0)) |
664 | wake_up_process(tsk->signal->group_exit_task); |
665 | write_unlock_irq(&tasklist_lock); |
666 | |
667 | /* If the process is dead, release it - nobody will wait for it */ |
668 | if (autoreap) |
669 | release_task(tsk); |
670 | } |
671 | |
672 | #ifdef CONFIG_DEBUG_STACK_USAGE |
673 | static void check_stack_usage(void) |
674 | { |
675 | static DEFINE_SPINLOCK(low_water_lock); |
676 | static int lowest_to_date = THREAD_SIZE; |
677 | unsigned long free; |
678 | |
679 | free = stack_not_used(current); |
680 | |
681 | if (free >= lowest_to_date) |
682 | return; |
683 | |
684 | spin_lock(&low_water_lock); |
685 | if (free < lowest_to_date) { |
686 | printk(KERN_WARNING "%s (%d) used greatest stack depth: " |
687 | "%lu bytes left\n", |
688 | current->comm, task_pid_nr(current), free); |
689 | lowest_to_date = free; |
690 | } |
691 | spin_unlock(&low_water_lock); |
692 | } |
693 | #else |
694 | static inline void check_stack_usage(void) {} |
695 | #endif |
696 | |
697 | void do_exit(long code) |
698 | { |
699 | struct task_struct *tsk = current; |
700 | int group_dead; |
701 | |
702 | profile_task_exit(tsk); |
703 | |
704 | WARN_ON(blk_needs_flush_plug(tsk)); |
705 | |
706 | if (unlikely(in_interrupt())) |
707 | panic("Aiee, killing interrupt handler!"); |
708 | if (unlikely(!tsk->pid)) |
709 | panic("Attempted to kill the idle task!"); |
710 | |
711 | /* |
712 | * If do_exit is called because this processes oopsed, it's possible |
713 | * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before |
714 | * continuing. Amongst other possible reasons, this is to prevent |
715 | * mm_release()->clear_child_tid() from writing to a user-controlled |
716 | * kernel address. |
717 | */ |
718 | set_fs(USER_DS); |
719 | |
720 | ptrace_event(PTRACE_EVENT_EXIT, code); |
721 | |
722 | validate_creds_for_do_exit(tsk); |
723 | |
724 | /* |
725 | * We're taking recursive faults here in do_exit. Safest is to just |
726 | * leave this task alone and wait for reboot. |
727 | */ |
728 | if (unlikely(tsk->flags & PF_EXITING)) { |
729 | printk(KERN_ALERT |
730 | "Fixing recursive fault but reboot is needed!\n"); |
731 | /* |
732 | * We can do this unlocked here. The futex code uses |
733 | * this flag just to verify whether the pi state |
734 | * cleanup has been done or not. In the worst case it |
735 | * loops once more. We pretend that the cleanup was |
736 | * done as there is no way to return. Either the |
737 | * OWNER_DIED bit is set by now or we push the blocked |
738 | * task into the wait for ever nirwana as well. |
739 | */ |
740 | tsk->flags |= PF_EXITPIDONE; |
741 | set_current_state(TASK_UNINTERRUPTIBLE); |
742 | schedule(); |
743 | } |
744 | |
745 | exit_signals(tsk); /* sets PF_EXITING */ |
746 | /* |
747 | * tsk->flags are checked in the futex code to protect against |
748 | * an exiting task cleaning up the robust pi futexes. |
749 | */ |
750 | smp_mb(); |
751 | raw_spin_unlock_wait(&tsk->pi_lock); |
752 | |
753 | if (unlikely(in_atomic())) |
754 | printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n", |
755 | current->comm, task_pid_nr(current), |
756 | preempt_count()); |
757 | |
758 | acct_update_integrals(tsk); |
759 | /* sync mm's RSS info before statistics gathering */ |
760 | if (tsk->mm) |
761 | sync_mm_rss(tsk->mm); |
762 | group_dead = atomic_dec_and_test(&tsk->signal->live); |
763 | if (group_dead) { |
764 | hrtimer_cancel(&tsk->signal->real_timer); |
765 | exit_itimers(tsk->signal); |
766 | if (tsk->mm) |
767 | setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); |
768 | } |
769 | acct_collect(code, group_dead); |
770 | if (group_dead) |
771 | tty_audit_exit(); |
772 | audit_free(tsk); |
773 | |
774 | tsk->exit_code = code; |
775 | taskstats_exit(tsk, group_dead); |
776 | |
777 | exit_mm(tsk); |
778 | |
779 | if (group_dead) |
780 | acct_process(); |
781 | trace_sched_process_exit(tsk); |
782 | |
783 | exit_sem(tsk); |
784 | exit_shm(tsk); |
785 | exit_files(tsk); |
786 | exit_fs(tsk); |
787 | if (group_dead) |
788 | disassociate_ctty(1); |
789 | exit_task_namespaces(tsk); |
790 | exit_task_work(tsk); |
791 | exit_thread(); |
792 | |
793 | /* |
794 | * Flush inherited counters to the parent - before the parent |
795 | * gets woken up by child-exit notifications. |
796 | * |
797 | * because of cgroup mode, must be called before cgroup_exit() |
798 | */ |
799 | perf_event_exit_task(tsk); |
800 | |
801 | cgroup_exit(tsk); |
802 | |
803 | module_put(task_thread_info(tsk)->exec_domain->module); |
804 | |
805 | /* |
806 | * FIXME: do that only when needed, using sched_exit tracepoint |
807 | */ |
808 | flush_ptrace_hw_breakpoint(tsk); |
809 | |
810 | exit_notify(tsk, group_dead); |
811 | proc_exit_connector(tsk); |
812 | #ifdef CONFIG_NUMA |
813 | task_lock(tsk); |
814 | mpol_put(tsk->mempolicy); |
815 | tsk->mempolicy = NULL; |
816 | task_unlock(tsk); |
817 | #endif |
818 | #ifdef CONFIG_FUTEX |
819 | if (unlikely(current->pi_state_cache)) |
820 | kfree(current->pi_state_cache); |
821 | #endif |
822 | /* |
823 | * Make sure we are holding no locks: |
824 | */ |
825 | debug_check_no_locks_held(); |
826 | /* |
827 | * We can do this unlocked here. The futex code uses this flag |
828 | * just to verify whether the pi state cleanup has been done |
829 | * or not. In the worst case it loops once more. |
830 | */ |
831 | tsk->flags |= PF_EXITPIDONE; |
832 | |
833 | if (tsk->io_context) |
834 | exit_io_context(tsk); |
835 | |
836 | if (tsk->splice_pipe) |
837 | free_pipe_info(tsk->splice_pipe); |
838 | |
839 | if (tsk->task_frag.page) |
840 | put_page(tsk->task_frag.page); |
841 | |
842 | validate_creds_for_do_exit(tsk); |
843 | |
844 | check_stack_usage(); |
845 | preempt_disable(); |
846 | if (tsk->nr_dirtied) |
847 | __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); |
848 | exit_rcu(); |
849 | |
850 | /* |
851 | * The setting of TASK_RUNNING by try_to_wake_up() may be delayed |
852 | * when the following two conditions become true. |
853 | * - There is race condition of mmap_sem (It is acquired by |
854 | * exit_mm()), and |
855 | * - SMI occurs before setting TASK_RUNINNG. |
856 | * (or hypervisor of virtual machine switches to other guest) |
857 | * As a result, we may become TASK_RUNNING after becoming TASK_DEAD |
858 | * |
859 | * To avoid it, we have to wait for releasing tsk->pi_lock which |
860 | * is held by try_to_wake_up() |
861 | */ |
862 | smp_mb(); |
863 | raw_spin_unlock_wait(&tsk->pi_lock); |
864 | |
865 | /* causes final put_task_struct in finish_task_switch(). */ |
866 | tsk->state = TASK_DEAD; |
867 | tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */ |
868 | schedule(); |
869 | BUG(); |
870 | /* Avoid "noreturn function does return". */ |
871 | for (;;) |
872 | cpu_relax(); /* For when BUG is null */ |
873 | } |
874 | |
875 | EXPORT_SYMBOL_GPL(do_exit); |
876 | |
877 | void complete_and_exit(struct completion *comp, long code) |
878 | { |
879 | if (comp) |
880 | complete(comp); |
881 | |
882 | do_exit(code); |
883 | } |
884 | |
885 | EXPORT_SYMBOL(complete_and_exit); |
886 | |
887 | SYSCALL_DEFINE1(exit, int, error_code) |
888 | { |
889 | do_exit((error_code&0xff)<<8); |
890 | } |
891 | |
892 | /* |
893 | * Take down every thread in the group. This is called by fatal signals |
894 | * as well as by sys_exit_group (below). |
895 | */ |
896 | void |
897 | do_group_exit(int exit_code) |
898 | { |
899 | struct signal_struct *sig = current->signal; |
900 | |
901 | BUG_ON(exit_code & 0x80); /* core dumps don't get here */ |
902 | |
903 | if (signal_group_exit(sig)) |
904 | exit_code = sig->group_exit_code; |
905 | else if (!thread_group_empty(current)) { |
906 | struct sighand_struct *const sighand = current->sighand; |
907 | spin_lock_irq(&sighand->siglock); |
908 | if (signal_group_exit(sig)) |
909 | /* Another thread got here before we took the lock. */ |
910 | exit_code = sig->group_exit_code; |
911 | else { |
912 | sig->group_exit_code = exit_code; |
913 | sig->flags = SIGNAL_GROUP_EXIT; |
914 | zap_other_threads(current); |
915 | } |
916 | spin_unlock_irq(&sighand->siglock); |
917 | } |
918 | |
919 | do_exit(exit_code); |
920 | /* NOTREACHED */ |
921 | } |
922 | |
923 | /* |
924 | * this kills every thread in the thread group. Note that any externally |
925 | * wait4()-ing process will get the correct exit code - even if this |
926 | * thread is not the thread group leader. |
927 | */ |
928 | SYSCALL_DEFINE1(exit_group, int, error_code) |
929 | { |
930 | do_group_exit((error_code & 0xff) << 8); |
931 | /* NOTREACHED */ |
932 | return 0; |
933 | } |
934 | |
935 | struct wait_opts { |
936 | enum pid_type wo_type; |
937 | int wo_flags; |
938 | struct pid *wo_pid; |
939 | |
940 | struct siginfo __user *wo_info; |
941 | int __user *wo_stat; |
942 | struct rusage __user *wo_rusage; |
943 | |
944 | wait_queue_t child_wait; |
945 | int notask_error; |
946 | }; |
947 | |
948 | static inline |
949 | struct pid *task_pid_type(struct task_struct *task, enum pid_type type) |
950 | { |
951 | if (type != PIDTYPE_PID) |
952 | task = task->group_leader; |
953 | return task->pids[type].pid; |
954 | } |
955 | |
956 | static int eligible_pid(struct wait_opts *wo, struct task_struct *p) |
957 | { |
958 | return wo->wo_type == PIDTYPE_MAX || |
959 | task_pid_type(p, wo->wo_type) == wo->wo_pid; |
960 | } |
961 | |
962 | static int eligible_child(struct wait_opts *wo, struct task_struct *p) |
963 | { |
964 | if (!eligible_pid(wo, p)) |
965 | return 0; |
966 | /* Wait for all children (clone and not) if __WALL is set; |
967 | * otherwise, wait for clone children *only* if __WCLONE is |
968 | * set; otherwise, wait for non-clone children *only*. (Note: |
969 | * A "clone" child here is one that reports to its parent |
970 | * using a signal other than SIGCHLD.) */ |
971 | if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) |
972 | && !(wo->wo_flags & __WALL)) |
973 | return 0; |
974 | |
975 | return 1; |
976 | } |
977 | |
978 | static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p, |
979 | pid_t pid, uid_t uid, int why, int status) |
980 | { |
981 | struct siginfo __user *infop; |
982 | int retval = wo->wo_rusage |
983 | ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; |
984 | |
985 | put_task_struct(p); |
986 | infop = wo->wo_info; |
987 | if (infop) { |
988 | if (!retval) |
989 | retval = put_user(SIGCHLD, &infop->si_signo); |
990 | if (!retval) |
991 | retval = put_user(0, &infop->si_errno); |
992 | if (!retval) |
993 | retval = put_user((short)why, &infop->si_code); |
994 | if (!retval) |
995 | retval = put_user(pid, &infop->si_pid); |
996 | if (!retval) |
997 | retval = put_user(uid, &infop->si_uid); |
998 | if (!retval) |
999 | retval = put_user(status, &infop->si_status); |
1000 | } |
1001 | if (!retval) |
1002 | retval = pid; |
1003 | return retval; |
1004 | } |
1005 | |
1006 | /* |
1007 | * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold |
1008 | * read_lock(&tasklist_lock) on entry. If we return zero, we still hold |
1009 | * the lock and this task is uninteresting. If we return nonzero, we have |
1010 | * released the lock and the system call should return. |
1011 | */ |
1012 | static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) |
1013 | { |
1014 | unsigned long state; |
1015 | int retval, status, traced; |
1016 | pid_t pid = task_pid_vnr(p); |
1017 | uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
1018 | struct siginfo __user *infop; |
1019 | |
1020 | if (!likely(wo->wo_flags & WEXITED)) |
1021 | return 0; |
1022 | |
1023 | if (unlikely(wo->wo_flags & WNOWAIT)) { |
1024 | int exit_code = p->exit_code; |
1025 | int why; |
1026 | |
1027 | get_task_struct(p); |
1028 | read_unlock(&tasklist_lock); |
1029 | if ((exit_code & 0x7f) == 0) { |
1030 | why = CLD_EXITED; |
1031 | status = exit_code >> 8; |
1032 | } else { |
1033 | why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED; |
1034 | status = exit_code & 0x7f; |
1035 | } |
1036 | return wait_noreap_copyout(wo, p, pid, uid, why, status); |
1037 | } |
1038 | |
1039 | traced = ptrace_reparented(p); |
1040 | /* |
1041 | * Move the task's state to DEAD/TRACE, only one thread can do this. |
1042 | */ |
1043 | state = traced && thread_group_leader(p) ? EXIT_TRACE : EXIT_DEAD; |
1044 | if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) |
1045 | return 0; |
1046 | /* |
1047 | * It can be ptraced but not reparented, check |
1048 | * thread_group_leader() to filter out sub-threads. |
1049 | */ |
1050 | if (likely(!traced) && thread_group_leader(p)) { |
1051 | struct signal_struct *psig; |
1052 | struct signal_struct *sig; |
1053 | unsigned long maxrss; |
1054 | cputime_t tgutime, tgstime; |
1055 | |
1056 | /* |
1057 | * The resource counters for the group leader are in its |
1058 | * own task_struct. Those for dead threads in the group |
1059 | * are in its signal_struct, as are those for the child |
1060 | * processes it has previously reaped. All these |
1061 | * accumulate in the parent's signal_struct c* fields. |
1062 | * |
1063 | * We don't bother to take a lock here to protect these |
1064 | * p->signal fields, because they are only touched by |
1065 | * __exit_signal, which runs with tasklist_lock |
1066 | * write-locked anyway, and so is excluded here. We do |
1067 | * need to protect the access to parent->signal fields, |
1068 | * as other threads in the parent group can be right |
1069 | * here reaping other children at the same time. |
1070 | * |
1071 | * We use thread_group_cputime_adjusted() to get times for the thread |
1072 | * group, which consolidates times for all threads in the |
1073 | * group including the group leader. |
1074 | */ |
1075 | thread_group_cputime_adjusted(p, &tgutime, &tgstime); |
1076 | spin_lock_irq(&p->real_parent->sighand->siglock); |
1077 | psig = p->real_parent->signal; |
1078 | sig = p->signal; |
1079 | psig->cutime += tgutime + sig->cutime; |
1080 | psig->cstime += tgstime + sig->cstime; |
1081 | psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime; |
1082 | psig->cmin_flt += |
1083 | p->min_flt + sig->min_flt + sig->cmin_flt; |
1084 | psig->cmaj_flt += |
1085 | p->maj_flt + sig->maj_flt + sig->cmaj_flt; |
1086 | psig->cnvcsw += |
1087 | p->nvcsw + sig->nvcsw + sig->cnvcsw; |
1088 | psig->cnivcsw += |
1089 | p->nivcsw + sig->nivcsw + sig->cnivcsw; |
1090 | psig->cinblock += |
1091 | task_io_get_inblock(p) + |
1092 | sig->inblock + sig->cinblock; |
1093 | psig->coublock += |
1094 | task_io_get_oublock(p) + |
1095 | sig->oublock + sig->coublock; |
1096 | maxrss = max(sig->maxrss, sig->cmaxrss); |
1097 | if (psig->cmaxrss < maxrss) |
1098 | psig->cmaxrss = maxrss; |
1099 | task_io_accounting_add(&psig->ioac, &p->ioac); |
1100 | task_io_accounting_add(&psig->ioac, &sig->ioac); |
1101 | spin_unlock_irq(&p->real_parent->sighand->siglock); |
1102 | } |
1103 | |
1104 | /* |
1105 | * Now we are sure this task is interesting, and no other |
1106 | * thread can reap it because we its state == DEAD/TRACE. |
1107 | */ |
1108 | read_unlock(&tasklist_lock); |
1109 | |
1110 | retval = wo->wo_rusage |
1111 | ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; |
1112 | status = (p->signal->flags & SIGNAL_GROUP_EXIT) |
1113 | ? p->signal->group_exit_code : p->exit_code; |
1114 | if (!retval && wo->wo_stat) |
1115 | retval = put_user(status, wo->wo_stat); |
1116 | |
1117 | infop = wo->wo_info; |
1118 | if (!retval && infop) |
1119 | retval = put_user(SIGCHLD, &infop->si_signo); |
1120 | if (!retval && infop) |
1121 | retval = put_user(0, &infop->si_errno); |
1122 | if (!retval && infop) { |
1123 | int why; |
1124 | |
1125 | if ((status & 0x7f) == 0) { |
1126 | why = CLD_EXITED; |
1127 | status >>= 8; |
1128 | } else { |
1129 | why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; |
1130 | status &= 0x7f; |
1131 | } |
1132 | retval = put_user((short)why, &infop->si_code); |
1133 | if (!retval) |
1134 | retval = put_user(status, &infop->si_status); |
1135 | } |
1136 | if (!retval && infop) |
1137 | retval = put_user(pid, &infop->si_pid); |
1138 | if (!retval && infop) |
1139 | retval = put_user(uid, &infop->si_uid); |
1140 | if (!retval) |
1141 | retval = pid; |
1142 | |
1143 | if (state == EXIT_TRACE) { |
1144 | write_lock_irq(&tasklist_lock); |
1145 | /* We dropped tasklist, ptracer could die and untrace */ |
1146 | ptrace_unlink(p); |
1147 | |
1148 | /* If parent wants a zombie, don't release it now */ |
1149 | state = EXIT_ZOMBIE; |
1150 | if (do_notify_parent(p, p->exit_signal)) |
1151 | state = EXIT_DEAD; |
1152 | p->exit_state = state; |
1153 | write_unlock_irq(&tasklist_lock); |
1154 | } |
1155 | if (state == EXIT_DEAD) |
1156 | release_task(p); |
1157 | |
1158 | return retval; |
1159 | } |
1160 | |
1161 | static int *task_stopped_code(struct task_struct *p, bool ptrace) |
1162 | { |
1163 | if (ptrace) { |
1164 | if (task_is_stopped_or_traced(p) && |
1165 | !(p->jobctl & JOBCTL_LISTENING)) |
1166 | return &p->exit_code; |
1167 | } else { |
1168 | if (p->signal->flags & SIGNAL_STOP_STOPPED) |
1169 | return &p->signal->group_exit_code; |
1170 | } |
1171 | return NULL; |
1172 | } |
1173 | |
1174 | /** |
1175 | * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED |
1176 | * @wo: wait options |
1177 | * @ptrace: is the wait for ptrace |
1178 | * @p: task to wait for |
1179 | * |
1180 | * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED. |
1181 | * |
1182 | * CONTEXT: |
1183 | * read_lock(&tasklist_lock), which is released if return value is |
1184 | * non-zero. Also, grabs and releases @p->sighand->siglock. |
1185 | * |
1186 | * RETURNS: |
1187 | * 0 if wait condition didn't exist and search for other wait conditions |
1188 | * should continue. Non-zero return, -errno on failure and @p's pid on |
1189 | * success, implies that tasklist_lock is released and wait condition |
1190 | * search should terminate. |
1191 | */ |
1192 | static int wait_task_stopped(struct wait_opts *wo, |
1193 | int ptrace, struct task_struct *p) |
1194 | { |
1195 | struct siginfo __user *infop; |
1196 | int retval, exit_code, *p_code, why; |
1197 | uid_t uid = 0; /* unneeded, required by compiler */ |
1198 | pid_t pid; |
1199 | |
1200 | /* |
1201 | * Traditionally we see ptrace'd stopped tasks regardless of options. |
1202 | */ |
1203 | if (!ptrace && !(wo->wo_flags & WUNTRACED)) |
1204 | return 0; |
1205 | |
1206 | if (!task_stopped_code(p, ptrace)) |
1207 | return 0; |
1208 | |
1209 | exit_code = 0; |
1210 | spin_lock_irq(&p->sighand->siglock); |
1211 | |
1212 | p_code = task_stopped_code(p, ptrace); |
1213 | if (unlikely(!p_code)) |
1214 | goto unlock_sig; |
1215 | |
1216 | exit_code = *p_code; |
1217 | if (!exit_code) |
1218 | goto unlock_sig; |
1219 | |
1220 | if (!unlikely(wo->wo_flags & WNOWAIT)) |
1221 | *p_code = 0; |
1222 | |
1223 | uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
1224 | unlock_sig: |
1225 | spin_unlock_irq(&p->sighand->siglock); |
1226 | if (!exit_code) |
1227 | return 0; |
1228 | |
1229 | /* |
1230 | * Now we are pretty sure this task is interesting. |
1231 | * Make sure it doesn't get reaped out from under us while we |
1232 | * give up the lock and then examine it below. We don't want to |
1233 | * keep holding onto the tasklist_lock while we call getrusage and |
1234 | * possibly take page faults for user memory. |
1235 | */ |
1236 | get_task_struct(p); |
1237 | pid = task_pid_vnr(p); |
1238 | why = ptrace ? CLD_TRAPPED : CLD_STOPPED; |
1239 | read_unlock(&tasklist_lock); |
1240 | |
1241 | if (unlikely(wo->wo_flags & WNOWAIT)) |
1242 | return wait_noreap_copyout(wo, p, pid, uid, why, exit_code); |
1243 | |
1244 | retval = wo->wo_rusage |
1245 | ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; |
1246 | if (!retval && wo->wo_stat) |
1247 | retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat); |
1248 | |
1249 | infop = wo->wo_info; |
1250 | if (!retval && infop) |
1251 | retval = put_user(SIGCHLD, &infop->si_signo); |
1252 | if (!retval && infop) |
1253 | retval = put_user(0, &infop->si_errno); |
1254 | if (!retval && infop) |
1255 | retval = put_user((short)why, &infop->si_code); |
1256 | if (!retval && infop) |
1257 | retval = put_user(exit_code, &infop->si_status); |
1258 | if (!retval && infop) |
1259 | retval = put_user(pid, &infop->si_pid); |
1260 | if (!retval && infop) |
1261 | retval = put_user(uid, &infop->si_uid); |
1262 | if (!retval) |
1263 | retval = pid; |
1264 | put_task_struct(p); |
1265 | |
1266 | BUG_ON(!retval); |
1267 | return retval; |
1268 | } |
1269 | |
1270 | /* |
1271 | * Handle do_wait work for one task in a live, non-stopped state. |
1272 | * read_lock(&tasklist_lock) on entry. If we return zero, we still hold |
1273 | * the lock and this task is uninteresting. If we return nonzero, we have |
1274 | * released the lock and the system call should return. |
1275 | */ |
1276 | static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) |
1277 | { |
1278 | int retval; |
1279 | pid_t pid; |
1280 | uid_t uid; |
1281 | |
1282 | if (!unlikely(wo->wo_flags & WCONTINUED)) |
1283 | return 0; |
1284 | |
1285 | if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) |
1286 | return 0; |
1287 | |
1288 | spin_lock_irq(&p->sighand->siglock); |
1289 | /* Re-check with the lock held. */ |
1290 | if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { |
1291 | spin_unlock_irq(&p->sighand->siglock); |
1292 | return 0; |
1293 | } |
1294 | if (!unlikely(wo->wo_flags & WNOWAIT)) |
1295 | p->signal->flags &= ~SIGNAL_STOP_CONTINUED; |
1296 | uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
1297 | spin_unlock_irq(&p->sighand->siglock); |
1298 | |
1299 | pid = task_pid_vnr(p); |
1300 | get_task_struct(p); |
1301 | read_unlock(&tasklist_lock); |
1302 | |
1303 | if (!wo->wo_info) { |
1304 | retval = wo->wo_rusage |
1305 | ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0; |
1306 | put_task_struct(p); |
1307 | if (!retval && wo->wo_stat) |
1308 | retval = put_user(0xffff, wo->wo_stat); |
1309 | if (!retval) |
1310 | retval = pid; |
1311 | } else { |
1312 | retval = wait_noreap_copyout(wo, p, pid, uid, |
1313 | CLD_CONTINUED, SIGCONT); |
1314 | BUG_ON(retval == 0); |
1315 | } |
1316 | |
1317 | return retval; |
1318 | } |
1319 | |
1320 | /* |
1321 | * Consider @p for a wait by @parent. |
1322 | * |
1323 | * -ECHILD should be in ->notask_error before the first call. |
1324 | * Returns nonzero for a final return, when we have unlocked tasklist_lock. |
1325 | * Returns zero if the search for a child should continue; |
1326 | * then ->notask_error is 0 if @p is an eligible child, |
1327 | * or another error from security_task_wait(), or still -ECHILD. |
1328 | */ |
1329 | static int wait_consider_task(struct wait_opts *wo, int ptrace, |
1330 | struct task_struct *p) |
1331 | { |
1332 | int ret; |
1333 | |
1334 | if (unlikely(p->exit_state == EXIT_DEAD)) |
1335 | return 0; |
1336 | |
1337 | ret = eligible_child(wo, p); |
1338 | if (!ret) |
1339 | return ret; |
1340 | |
1341 | ret = security_task_wait(p); |
1342 | if (unlikely(ret < 0)) { |
1343 | /* |
1344 | * If we have not yet seen any eligible child, |
1345 | * then let this error code replace -ECHILD. |
1346 | * A permission error will give the user a clue |
1347 | * to look for security policy problems, rather |
1348 | * than for mysterious wait bugs. |
1349 | */ |
1350 | if (wo->notask_error) |
1351 | wo->notask_error = ret; |
1352 | return 0; |
1353 | } |
1354 | |
1355 | if (unlikely(p->exit_state == EXIT_TRACE)) { |
1356 | /* |
1357 | * ptrace == 0 means we are the natural parent. In this case |
1358 | * we should clear notask_error, debugger will notify us. |
1359 | */ |
1360 | if (likely(!ptrace)) |
1361 | wo->notask_error = 0; |
1362 | return 0; |
1363 | } |
1364 | |
1365 | if (likely(!ptrace) && unlikely(p->ptrace)) { |
1366 | /* |
1367 | * If it is traced by its real parent's group, just pretend |
1368 | * the caller is ptrace_do_wait() and reap this child if it |
1369 | * is zombie. |
1370 | * |
1371 | * This also hides group stop state from real parent; otherwise |
1372 | * a single stop can be reported twice as group and ptrace stop. |
1373 | * If a ptracer wants to distinguish these two events for its |
1374 | * own children it should create a separate process which takes |
1375 | * the role of real parent. |
1376 | */ |
1377 | if (!ptrace_reparented(p)) |
1378 | ptrace = 1; |
1379 | } |
1380 | |
1381 | /* slay zombie? */ |
1382 | if (p->exit_state == EXIT_ZOMBIE) { |
1383 | /* we don't reap group leaders with subthreads */ |
1384 | if (!delay_group_leader(p)) { |
1385 | /* |
1386 | * A zombie ptracee is only visible to its ptracer. |
1387 | * Notification and reaping will be cascaded to the |
1388 | * real parent when the ptracer detaches. |
1389 | */ |
1390 | if (unlikely(ptrace) || likely(!p->ptrace)) |
1391 | return wait_task_zombie(wo, p); |
1392 | } |
1393 | |
1394 | /* |
1395 | * Allow access to stopped/continued state via zombie by |
1396 | * falling through. Clearing of notask_error is complex. |
1397 | * |
1398 | * When !@ptrace: |
1399 | * |
1400 | * If WEXITED is set, notask_error should naturally be |
1401 | * cleared. If not, subset of WSTOPPED|WCONTINUED is set, |
1402 | * so, if there are live subthreads, there are events to |
1403 | * wait for. If all subthreads are dead, it's still safe |
1404 | * to clear - this function will be called again in finite |
1405 | * amount time once all the subthreads are released and |
1406 | * will then return without clearing. |
1407 | * |
1408 | * When @ptrace: |
1409 | * |
1410 | * Stopped state is per-task and thus can't change once the |
1411 | * target task dies. Only continued and exited can happen. |
1412 | * Clear notask_error if WCONTINUED | WEXITED. |
1413 | */ |
1414 | if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED))) |
1415 | wo->notask_error = 0; |
1416 | } else { |
1417 | /* |
1418 | * @p is alive and it's gonna stop, continue or exit, so |
1419 | * there always is something to wait for. |
1420 | */ |
1421 | wo->notask_error = 0; |
1422 | } |
1423 | |
1424 | /* |
1425 | * Wait for stopped. Depending on @ptrace, different stopped state |
1426 | * is used and the two don't interact with each other. |
1427 | */ |
1428 | ret = wait_task_stopped(wo, ptrace, p); |
1429 | if (ret) |
1430 | return ret; |
1431 | |
1432 | /* |
1433 | * Wait for continued. There's only one continued state and the |
1434 | * ptracer can consume it which can confuse the real parent. Don't |
1435 | * use WCONTINUED from ptracer. You don't need or want it. |
1436 | */ |
1437 | return wait_task_continued(wo, p); |
1438 | } |
1439 | |
1440 | /* |
1441 | * Do the work of do_wait() for one thread in the group, @tsk. |
1442 | * |
1443 | * -ECHILD should be in ->notask_error before the first call. |
1444 | * Returns nonzero for a final return, when we have unlocked tasklist_lock. |
1445 | * Returns zero if the search for a child should continue; then |
1446 | * ->notask_error is 0 if there were any eligible children, |
1447 | * or another error from security_task_wait(), or still -ECHILD. |
1448 | */ |
1449 | static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) |
1450 | { |
1451 | struct task_struct *p; |
1452 | |
1453 | list_for_each_entry(p, &tsk->children, sibling) { |
1454 | int ret = wait_consider_task(wo, 0, p); |
1455 | if (ret) |
1456 | return ret; |
1457 | } |
1458 | |
1459 | return 0; |
1460 | } |
1461 | |
1462 | static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) |
1463 | { |
1464 | struct task_struct *p; |
1465 | |
1466 | list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { |
1467 | int ret = wait_consider_task(wo, 1, p); |
1468 | if (ret) |
1469 | return ret; |
1470 | } |
1471 | |
1472 | return 0; |
1473 | } |
1474 | |
1475 | static int child_wait_callback(wait_queue_t *wait, unsigned mode, |
1476 | int sync, void *key) |
1477 | { |
1478 | struct wait_opts *wo = container_of(wait, struct wait_opts, |
1479 | child_wait); |
1480 | struct task_struct *p = key; |
1481 | |
1482 | if (!eligible_pid(wo, p)) |
1483 | return 0; |
1484 | |
1485 | if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) |
1486 | return 0; |
1487 | |
1488 | return default_wake_function(wait, mode, sync, key); |
1489 | } |
1490 | |
1491 | void __wake_up_parent(struct task_struct *p, struct task_struct *parent) |
1492 | { |
1493 | __wake_up_sync_key(&parent->signal->wait_chldexit, |
1494 | TASK_INTERRUPTIBLE, 1, p); |
1495 | } |
1496 | |
1497 | static long do_wait(struct wait_opts *wo) |
1498 | { |
1499 | struct task_struct *tsk; |
1500 | int retval; |
1501 | |
1502 | trace_sched_process_wait(wo->wo_pid); |
1503 | |
1504 | init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); |
1505 | wo->child_wait.private = current; |
1506 | add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); |
1507 | repeat: |
1508 | /* |
1509 | * If there is nothing that can match our critiera just get out. |
1510 | * We will clear ->notask_error to zero if we see any child that |
1511 | * might later match our criteria, even if we are not able to reap |
1512 | * it yet. |
1513 | */ |
1514 | wo->notask_error = -ECHILD; |
1515 | if ((wo->wo_type < PIDTYPE_MAX) && |
1516 | (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type]))) |
1517 | goto notask; |
1518 | |
1519 | set_current_state(TASK_INTERRUPTIBLE); |
1520 | read_lock(&tasklist_lock); |
1521 | tsk = current; |
1522 | do { |
1523 | retval = do_wait_thread(wo, tsk); |
1524 | if (retval) |
1525 | goto end; |
1526 | |
1527 | retval = ptrace_do_wait(wo, tsk); |
1528 | if (retval) |
1529 | goto end; |
1530 | |
1531 | if (wo->wo_flags & __WNOTHREAD) |
1532 | break; |
1533 | } while_each_thread(current, tsk); |
1534 | read_unlock(&tasklist_lock); |
1535 | |
1536 | notask: |
1537 | retval = wo->notask_error; |
1538 | if (!retval && !(wo->wo_flags & WNOHANG)) { |
1539 | retval = -ERESTARTSYS; |
1540 | if (!signal_pending(current)) { |
1541 | schedule(); |
1542 | goto repeat; |
1543 | } |
1544 | } |
1545 | end: |
1546 | __set_current_state(TASK_RUNNING); |
1547 | remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); |
1548 | return retval; |
1549 | } |
1550 | |
1551 | SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, |
1552 | infop, int, options, struct rusage __user *, ru) |
1553 | { |
1554 | struct wait_opts wo; |
1555 | struct pid *pid = NULL; |
1556 | enum pid_type type; |
1557 | long ret; |
1558 | |
1559 | if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED)) |
1560 | return -EINVAL; |
1561 | if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) |
1562 | return -EINVAL; |
1563 | |
1564 | switch (which) { |
1565 | case P_ALL: |
1566 | type = PIDTYPE_MAX; |
1567 | break; |
1568 | case P_PID: |
1569 | type = PIDTYPE_PID; |
1570 | if (upid <= 0) |
1571 | return -EINVAL; |
1572 | break; |
1573 | case P_PGID: |
1574 | type = PIDTYPE_PGID; |
1575 | if (upid <= 0) |
1576 | return -EINVAL; |
1577 | break; |
1578 | default: |
1579 | return -EINVAL; |
1580 | } |
1581 | |
1582 | if (type < PIDTYPE_MAX) |
1583 | pid = find_get_pid(upid); |
1584 | |
1585 | wo.wo_type = type; |
1586 | wo.wo_pid = pid; |
1587 | wo.wo_flags = options; |
1588 | wo.wo_info = infop; |
1589 | wo.wo_stat = NULL; |
1590 | wo.wo_rusage = ru; |
1591 | ret = do_wait(&wo); |
1592 | |
1593 | if (ret > 0) { |
1594 | ret = 0; |
1595 | } else if (infop) { |
1596 | /* |
1597 | * For a WNOHANG return, clear out all the fields |
1598 | * we would set so the user can easily tell the |
1599 | * difference. |
1600 | */ |
1601 | if (!ret) |
1602 | ret = put_user(0, &infop->si_signo); |
1603 | if (!ret) |
1604 | ret = put_user(0, &infop->si_errno); |
1605 | if (!ret) |
1606 | ret = put_user(0, &infop->si_code); |
1607 | if (!ret) |
1608 | ret = put_user(0, &infop->si_pid); |
1609 | if (!ret) |
1610 | ret = put_user(0, &infop->si_uid); |
1611 | if (!ret) |
1612 | ret = put_user(0, &infop->si_status); |
1613 | } |
1614 | |
1615 | put_pid(pid); |
1616 | return ret; |
1617 | } |
1618 | |
1619 | SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, |
1620 | int, options, struct rusage __user *, ru) |
1621 | { |
1622 | struct wait_opts wo; |
1623 | struct pid *pid = NULL; |
1624 | enum pid_type type; |
1625 | long ret; |
1626 | |
1627 | if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| |
1628 | __WNOTHREAD|__WCLONE|__WALL)) |
1629 | return -EINVAL; |
1630 | |
1631 | if (upid == -1) |
1632 | type = PIDTYPE_MAX; |
1633 | else if (upid < 0) { |
1634 | type = PIDTYPE_PGID; |
1635 | pid = find_get_pid(-upid); |
1636 | } else if (upid == 0) { |
1637 | type = PIDTYPE_PGID; |
1638 | pid = get_task_pid(current, PIDTYPE_PGID); |
1639 | } else /* upid > 0 */ { |
1640 | type = PIDTYPE_PID; |
1641 | pid = find_get_pid(upid); |
1642 | } |
1643 | |
1644 | wo.wo_type = type; |
1645 | wo.wo_pid = pid; |
1646 | wo.wo_flags = options | WEXITED; |
1647 | wo.wo_info = NULL; |
1648 | wo.wo_stat = stat_addr; |
1649 | wo.wo_rusage = ru; |
1650 | ret = do_wait(&wo); |
1651 | put_pid(pid); |
1652 | |
1653 | return ret; |
1654 | } |
1655 | |
1656 | #ifdef __ARCH_WANT_SYS_WAITPID |
1657 | |
1658 | /* |
1659 | * sys_waitpid() remains for compatibility. waitpid() should be |
1660 | * implemented by calling sys_wait4() from libc.a. |
1661 | */ |
1662 | SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) |
1663 | { |
1664 | return sys_wait4(pid, stat_addr, options, NULL); |
1665 | } |
1666 | |
1667 | #endif |
1668 |
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