1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * linux/kernel/exit.c |
4 | * |
5 | * Copyright (C) 1991, 1992 Linus Torvalds |
6 | */ |
7 | |
8 | #include <linux/mm.h> |
9 | #include <linux/slab.h> |
10 | #include <linux/sched/autogroup.h> |
11 | #include <linux/sched/mm.h> |
12 | #include <linux/sched/stat.h> |
13 | #include <linux/sched/task.h> |
14 | #include <linux/sched/task_stack.h> |
15 | #include <linux/sched/cputime.h> |
16 | #include <linux/interrupt.h> |
17 | #include <linux/module.h> |
18 | #include <linux/capability.h> |
19 | #include <linux/completion.h> |
20 | #include <linux/personality.h> |
21 | #include <linux/tty.h> |
22 | #include <linux/iocontext.h> |
23 | #include <linux/key.h> |
24 | #include <linux/cpu.h> |
25 | #include <linux/acct.h> |
26 | #include <linux/tsacct_kern.h> |
27 | #include <linux/file.h> |
28 | #include <linux/fdtable.h> |
29 | #include <linux/freezer.h> |
30 | #include <linux/binfmts.h> |
31 | #include <linux/nsproxy.h> |
32 | #include <linux/pid_namespace.h> |
33 | #include <linux/ptrace.h> |
34 | #include <linux/profile.h> |
35 | #include <linux/mount.h> |
36 | #include <linux/proc_fs.h> |
37 | #include <linux/kthread.h> |
38 | #include <linux/mempolicy.h> |
39 | #include <linux/taskstats_kern.h> |
40 | #include <linux/delayacct.h> |
41 | #include <linux/cgroup.h> |
42 | #include <linux/syscalls.h> |
43 | #include <linux/signal.h> |
44 | #include <linux/posix-timers.h> |
45 | #include <linux/cn_proc.h> |
46 | #include <linux/mutex.h> |
47 | #include <linux/futex.h> |
48 | #include <linux/pipe_fs_i.h> |
49 | #include <linux/audit.h> /* for audit_free() */ |
50 | #include <linux/resource.h> |
51 | #include <linux/task_io_accounting_ops.h> |
52 | #include <linux/blkdev.h> |
53 | #include <linux/task_work.h> |
54 | #include <linux/fs_struct.h> |
55 | #include <linux/init_task.h> |
56 | #include <linux/perf_event.h> |
57 | #include <trace/events/sched.h> |
58 | #include <linux/hw_breakpoint.h> |
59 | #include <linux/oom.h> |
60 | #include <linux/writeback.h> |
61 | #include <linux/shm.h> |
62 | #include <linux/kcov.h> |
63 | #include <linux/kmsan.h> |
64 | #include <linux/random.h> |
65 | #include <linux/rcuwait.h> |
66 | #include <linux/compat.h> |
67 | #include <linux/io_uring.h> |
68 | #include <linux/kprobes.h> |
69 | #include <linux/rethook.h> |
70 | #include <linux/sysfs.h> |
71 | #include <linux/user_events.h> |
72 | |
73 | #include <linux/uaccess.h> |
74 | #include <asm/unistd.h> |
75 | #include <asm/mmu_context.h> |
76 | |
77 | #include "exit.h" |
78 | |
79 | /* |
80 | * The default value should be high enough to not crash a system that randomly |
81 | * crashes its kernel from time to time, but low enough to at least not permit |
82 | * overflowing 32-bit refcounts or the ldsem writer count. |
83 | */ |
84 | static unsigned int oops_limit = 10000; |
85 | |
86 | #ifdef CONFIG_SYSCTL |
87 | static struct ctl_table kern_exit_table[] = { |
88 | { |
89 | .procname = "oops_limit" , |
90 | .data = &oops_limit, |
91 | .maxlen = sizeof(oops_limit), |
92 | .mode = 0644, |
93 | .proc_handler = proc_douintvec, |
94 | }, |
95 | { } |
96 | }; |
97 | |
98 | static __init int kernel_exit_sysctls_init(void) |
99 | { |
100 | register_sysctl_init("kernel" , kern_exit_table); |
101 | return 0; |
102 | } |
103 | late_initcall(kernel_exit_sysctls_init); |
104 | #endif |
105 | |
106 | static atomic_t oops_count = ATOMIC_INIT(0); |
107 | |
108 | #ifdef CONFIG_SYSFS |
109 | static ssize_t oops_count_show(struct kobject *kobj, struct kobj_attribute *attr, |
110 | char *page) |
111 | { |
112 | return sysfs_emit(buf: page, fmt: "%d\n" , atomic_read(v: &oops_count)); |
113 | } |
114 | |
115 | static struct kobj_attribute oops_count_attr = __ATTR_RO(oops_count); |
116 | |
117 | static __init int kernel_exit_sysfs_init(void) |
118 | { |
119 | sysfs_add_file_to_group(kobj: kernel_kobj, attr: &oops_count_attr.attr, NULL); |
120 | return 0; |
121 | } |
122 | late_initcall(kernel_exit_sysfs_init); |
123 | #endif |
124 | |
125 | static void __unhash_process(struct task_struct *p, bool group_dead) |
126 | { |
127 | nr_threads--; |
128 | detach_pid(task: p, PIDTYPE_PID); |
129 | if (group_dead) { |
130 | detach_pid(task: p, PIDTYPE_TGID); |
131 | detach_pid(task: p, PIDTYPE_PGID); |
132 | detach_pid(task: p, PIDTYPE_SID); |
133 | |
134 | list_del_rcu(entry: &p->tasks); |
135 | list_del_init(entry: &p->sibling); |
136 | __this_cpu_dec(process_counts); |
137 | } |
138 | list_del_rcu(entry: &p->thread_node); |
139 | } |
140 | |
141 | /* |
142 | * This function expects the tasklist_lock write-locked. |
143 | */ |
144 | static void __exit_signal(struct task_struct *tsk) |
145 | { |
146 | struct signal_struct *sig = tsk->signal; |
147 | bool group_dead = thread_group_leader(p: tsk); |
148 | struct sighand_struct *sighand; |
149 | struct tty_struct *tty; |
150 | u64 utime, stime; |
151 | |
152 | sighand = rcu_dereference_check(tsk->sighand, |
153 | lockdep_tasklist_lock_is_held()); |
154 | spin_lock(lock: &sighand->siglock); |
155 | |
156 | #ifdef CONFIG_POSIX_TIMERS |
157 | posix_cpu_timers_exit(task: tsk); |
158 | if (group_dead) |
159 | posix_cpu_timers_exit_group(task: tsk); |
160 | #endif |
161 | |
162 | if (group_dead) { |
163 | tty = sig->tty; |
164 | sig->tty = NULL; |
165 | } else { |
166 | /* |
167 | * If there is any task waiting for the group exit |
168 | * then notify it: |
169 | */ |
170 | if (sig->notify_count > 0 && !--sig->notify_count) |
171 | wake_up_process(tsk: sig->group_exec_task); |
172 | |
173 | if (tsk == sig->curr_target) |
174 | sig->curr_target = next_thread(p: tsk); |
175 | } |
176 | |
177 | add_device_randomness(buf: (const void*) &tsk->se.sum_exec_runtime, |
178 | len: sizeof(unsigned long long)); |
179 | |
180 | /* |
181 | * Accumulate here the counters for all threads as they die. We could |
182 | * skip the group leader because it is the last user of signal_struct, |
183 | * but we want to avoid the race with thread_group_cputime() which can |
184 | * see the empty ->thread_head list. |
185 | */ |
186 | task_cputime(t: tsk, utime: &utime, stime: &stime); |
187 | write_seqlock(sl: &sig->stats_lock); |
188 | sig->utime += utime; |
189 | sig->stime += stime; |
190 | sig->gtime += task_gtime(t: tsk); |
191 | sig->min_flt += tsk->min_flt; |
192 | sig->maj_flt += tsk->maj_flt; |
193 | sig->nvcsw += tsk->nvcsw; |
194 | sig->nivcsw += tsk->nivcsw; |
195 | sig->inblock += task_io_get_inblock(p: tsk); |
196 | sig->oublock += task_io_get_oublock(p: tsk); |
197 | task_io_accounting_add(dst: &sig->ioac, src: &tsk->ioac); |
198 | sig->sum_sched_runtime += tsk->se.sum_exec_runtime; |
199 | sig->nr_threads--; |
200 | __unhash_process(p: tsk, group_dead); |
201 | write_sequnlock(sl: &sig->stats_lock); |
202 | |
203 | /* |
204 | * Do this under ->siglock, we can race with another thread |
205 | * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. |
206 | */ |
207 | flush_sigqueue(queue: &tsk->pending); |
208 | tsk->sighand = NULL; |
209 | spin_unlock(lock: &sighand->siglock); |
210 | |
211 | __cleanup_sighand(sighand); |
212 | clear_tsk_thread_flag(tsk, TIF_SIGPENDING); |
213 | if (group_dead) { |
214 | flush_sigqueue(queue: &sig->shared_pending); |
215 | tty_kref_put(tty); |
216 | } |
217 | } |
218 | |
219 | static void delayed_put_task_struct(struct rcu_head *rhp) |
220 | { |
221 | struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); |
222 | |
223 | kprobe_flush_task(tsk); |
224 | rethook_flush_task(tk: tsk); |
225 | perf_event_delayed_put(task: tsk); |
226 | trace_sched_process_free(p: tsk); |
227 | put_task_struct(t: tsk); |
228 | } |
229 | |
230 | void put_task_struct_rcu_user(struct task_struct *task) |
231 | { |
232 | if (refcount_dec_and_test(r: &task->rcu_users)) |
233 | call_rcu(head: &task->rcu, func: delayed_put_task_struct); |
234 | } |
235 | |
236 | void __weak release_thread(struct task_struct *dead_task) |
237 | { |
238 | } |
239 | |
240 | void release_task(struct task_struct *p) |
241 | { |
242 | struct task_struct *leader; |
243 | struct pid *thread_pid; |
244 | int zap_leader; |
245 | repeat: |
246 | /* don't need to get the RCU readlock here - the process is dead and |
247 | * can't be modifying its own credentials. But shut RCU-lockdep up */ |
248 | rcu_read_lock(); |
249 | dec_rlimit_ucounts(task_ucounts(p), type: UCOUNT_RLIMIT_NPROC, v: 1); |
250 | rcu_read_unlock(); |
251 | |
252 | cgroup_release(p); |
253 | |
254 | write_lock_irq(&tasklist_lock); |
255 | ptrace_release_task(task: p); |
256 | thread_pid = get_pid(pid: p->thread_pid); |
257 | __exit_signal(tsk: p); |
258 | |
259 | /* |
260 | * If we are the last non-leader member of the thread |
261 | * group, and the leader is zombie, then notify the |
262 | * group leader's parent process. (if it wants notification.) |
263 | */ |
264 | zap_leader = 0; |
265 | leader = p->group_leader; |
266 | if (leader != p && thread_group_empty(p: leader) |
267 | && leader->exit_state == EXIT_ZOMBIE) { |
268 | /* |
269 | * If we were the last child thread and the leader has |
270 | * exited already, and the leader's parent ignores SIGCHLD, |
271 | * then we are the one who should release the leader. |
272 | */ |
273 | zap_leader = do_notify_parent(leader, leader->exit_signal); |
274 | if (zap_leader) |
275 | leader->exit_state = EXIT_DEAD; |
276 | } |
277 | |
278 | write_unlock_irq(&tasklist_lock); |
279 | seccomp_filter_release(tsk: p); |
280 | proc_flush_pid(thread_pid); |
281 | put_pid(pid: thread_pid); |
282 | release_thread(dead_task: p); |
283 | put_task_struct_rcu_user(task: p); |
284 | |
285 | p = leader; |
286 | if (unlikely(zap_leader)) |
287 | goto repeat; |
288 | } |
289 | |
290 | int rcuwait_wake_up(struct rcuwait *w) |
291 | { |
292 | int ret = 0; |
293 | struct task_struct *task; |
294 | |
295 | rcu_read_lock(); |
296 | |
297 | /* |
298 | * Order condition vs @task, such that everything prior to the load |
299 | * of @task is visible. This is the condition as to why the user called |
300 | * rcuwait_wake() in the first place. Pairs with set_current_state() |
301 | * barrier (A) in rcuwait_wait_event(). |
302 | * |
303 | * WAIT WAKE |
304 | * [S] tsk = current [S] cond = true |
305 | * MB (A) MB (B) |
306 | * [L] cond [L] tsk |
307 | */ |
308 | smp_mb(); /* (B) */ |
309 | |
310 | task = rcu_dereference(w->task); |
311 | if (task) |
312 | ret = wake_up_process(tsk: task); |
313 | rcu_read_unlock(); |
314 | |
315 | return ret; |
316 | } |
317 | EXPORT_SYMBOL_GPL(rcuwait_wake_up); |
318 | |
319 | /* |
320 | * Determine if a process group is "orphaned", according to the POSIX |
321 | * definition in 2.2.2.52. Orphaned process groups are not to be affected |
322 | * by terminal-generated stop signals. Newly orphaned process groups are |
323 | * to receive a SIGHUP and a SIGCONT. |
324 | * |
325 | * "I ask you, have you ever known what it is to be an orphan?" |
326 | */ |
327 | static int will_become_orphaned_pgrp(struct pid *pgrp, |
328 | struct task_struct *ignored_task) |
329 | { |
330 | struct task_struct *p; |
331 | |
332 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
333 | if ((p == ignored_task) || |
334 | (p->exit_state && thread_group_empty(p)) || |
335 | is_global_init(tsk: p->real_parent)) |
336 | continue; |
337 | |
338 | if (task_pgrp(task: p->real_parent) != pgrp && |
339 | task_session(task: p->real_parent) == task_session(task: p)) |
340 | return 0; |
341 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
342 | |
343 | return 1; |
344 | } |
345 | |
346 | int is_current_pgrp_orphaned(void) |
347 | { |
348 | int retval; |
349 | |
350 | read_lock(&tasklist_lock); |
351 | retval = will_become_orphaned_pgrp(pgrp: task_pgrp(current), NULL); |
352 | read_unlock(&tasklist_lock); |
353 | |
354 | return retval; |
355 | } |
356 | |
357 | static bool has_stopped_jobs(struct pid *pgrp) |
358 | { |
359 | struct task_struct *p; |
360 | |
361 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
362 | if (p->signal->flags & SIGNAL_STOP_STOPPED) |
363 | return true; |
364 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
365 | |
366 | return false; |
367 | } |
368 | |
369 | /* |
370 | * Check to see if any process groups have become orphaned as |
371 | * a result of our exiting, and if they have any stopped jobs, |
372 | * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) |
373 | */ |
374 | static void |
375 | kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) |
376 | { |
377 | struct pid *pgrp = task_pgrp(task: tsk); |
378 | struct task_struct *ignored_task = tsk; |
379 | |
380 | if (!parent) |
381 | /* exit: our father is in a different pgrp than |
382 | * we are and we were the only connection outside. |
383 | */ |
384 | parent = tsk->real_parent; |
385 | else |
386 | /* reparent: our child is in a different pgrp than |
387 | * we are, and it was the only connection outside. |
388 | */ |
389 | ignored_task = NULL; |
390 | |
391 | if (task_pgrp(task: parent) != pgrp && |
392 | task_session(task: parent) == task_session(task: tsk) && |
393 | will_become_orphaned_pgrp(pgrp, ignored_task) && |
394 | has_stopped_jobs(pgrp)) { |
395 | __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); |
396 | __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); |
397 | } |
398 | } |
399 | |
400 | static void coredump_task_exit(struct task_struct *tsk) |
401 | { |
402 | struct core_state *core_state; |
403 | |
404 | /* |
405 | * Serialize with any possible pending coredump. |
406 | * We must hold siglock around checking core_state |
407 | * and setting PF_POSTCOREDUMP. The core-inducing thread |
408 | * will increment ->nr_threads for each thread in the |
409 | * group without PF_POSTCOREDUMP set. |
410 | */ |
411 | spin_lock_irq(lock: &tsk->sighand->siglock); |
412 | tsk->flags |= PF_POSTCOREDUMP; |
413 | core_state = tsk->signal->core_state; |
414 | spin_unlock_irq(lock: &tsk->sighand->siglock); |
415 | |
416 | /* The vhost_worker does not particpate in coredumps */ |
417 | if (core_state && |
418 | ((tsk->flags & (PF_IO_WORKER | PF_USER_WORKER)) != PF_USER_WORKER)) { |
419 | struct core_thread self; |
420 | |
421 | self.task = current; |
422 | if (self.task->flags & PF_SIGNALED) |
423 | self.next = xchg(&core_state->dumper.next, &self); |
424 | else |
425 | self.task = NULL; |
426 | /* |
427 | * Implies mb(), the result of xchg() must be visible |
428 | * to core_state->dumper. |
429 | */ |
430 | if (atomic_dec_and_test(v: &core_state->nr_threads)) |
431 | complete(&core_state->startup); |
432 | |
433 | for (;;) { |
434 | set_current_state(TASK_UNINTERRUPTIBLE|TASK_FREEZABLE); |
435 | if (!self.task) /* see coredump_finish() */ |
436 | break; |
437 | schedule(); |
438 | } |
439 | __set_current_state(TASK_RUNNING); |
440 | } |
441 | } |
442 | |
443 | #ifdef CONFIG_MEMCG |
444 | /* |
445 | * A task is exiting. If it owned this mm, find a new owner for the mm. |
446 | */ |
447 | void mm_update_next_owner(struct mm_struct *mm) |
448 | { |
449 | struct task_struct *c, *g, *p = current; |
450 | |
451 | retry: |
452 | /* |
453 | * If the exiting or execing task is not the owner, it's |
454 | * someone else's problem. |
455 | */ |
456 | if (mm->owner != p) |
457 | return; |
458 | /* |
459 | * The current owner is exiting/execing and there are no other |
460 | * candidates. Do not leave the mm pointing to a possibly |
461 | * freed task structure. |
462 | */ |
463 | if (atomic_read(v: &mm->mm_users) <= 1) { |
464 | WRITE_ONCE(mm->owner, NULL); |
465 | return; |
466 | } |
467 | |
468 | read_lock(&tasklist_lock); |
469 | /* |
470 | * Search in the children |
471 | */ |
472 | list_for_each_entry(c, &p->children, sibling) { |
473 | if (c->mm == mm) |
474 | goto assign_new_owner; |
475 | } |
476 | |
477 | /* |
478 | * Search in the siblings |
479 | */ |
480 | list_for_each_entry(c, &p->real_parent->children, sibling) { |
481 | if (c->mm == mm) |
482 | goto assign_new_owner; |
483 | } |
484 | |
485 | /* |
486 | * Search through everything else, we should not get here often. |
487 | */ |
488 | for_each_process(g) { |
489 | if (g->flags & PF_KTHREAD) |
490 | continue; |
491 | for_each_thread(g, c) { |
492 | if (c->mm == mm) |
493 | goto assign_new_owner; |
494 | if (c->mm) |
495 | break; |
496 | } |
497 | } |
498 | read_unlock(&tasklist_lock); |
499 | /* |
500 | * We found no owner yet mm_users > 1: this implies that we are |
501 | * most likely racing with swapoff (try_to_unuse()) or /proc or |
502 | * ptrace or page migration (get_task_mm()). Mark owner as NULL. |
503 | */ |
504 | WRITE_ONCE(mm->owner, NULL); |
505 | return; |
506 | |
507 | assign_new_owner: |
508 | BUG_ON(c == p); |
509 | get_task_struct(t: c); |
510 | /* |
511 | * The task_lock protects c->mm from changing. |
512 | * We always want mm->owner->mm == mm |
513 | */ |
514 | task_lock(p: c); |
515 | /* |
516 | * Delay read_unlock() till we have the task_lock() |
517 | * to ensure that c does not slip away underneath us |
518 | */ |
519 | read_unlock(&tasklist_lock); |
520 | if (c->mm != mm) { |
521 | task_unlock(p: c); |
522 | put_task_struct(t: c); |
523 | goto retry; |
524 | } |
525 | WRITE_ONCE(mm->owner, c); |
526 | lru_gen_migrate_mm(mm); |
527 | task_unlock(p: c); |
528 | put_task_struct(t: c); |
529 | } |
530 | #endif /* CONFIG_MEMCG */ |
531 | |
532 | /* |
533 | * Turn us into a lazy TLB process if we |
534 | * aren't already.. |
535 | */ |
536 | static void exit_mm(void) |
537 | { |
538 | struct mm_struct *mm = current->mm; |
539 | |
540 | exit_mm_release(current, mm); |
541 | if (!mm) |
542 | return; |
543 | mmap_read_lock(mm); |
544 | mmgrab_lazy_tlb(mm); |
545 | BUG_ON(mm != current->active_mm); |
546 | /* more a memory barrier than a real lock */ |
547 | task_lock(current); |
548 | /* |
549 | * When a thread stops operating on an address space, the loop |
550 | * in membarrier_private_expedited() may not observe that |
551 | * tsk->mm, and the loop in membarrier_global_expedited() may |
552 | * not observe a MEMBARRIER_STATE_GLOBAL_EXPEDITED |
553 | * rq->membarrier_state, so those would not issue an IPI. |
554 | * Membarrier requires a memory barrier after accessing |
555 | * user-space memory, before clearing tsk->mm or the |
556 | * rq->membarrier_state. |
557 | */ |
558 | smp_mb__after_spinlock(); |
559 | local_irq_disable(); |
560 | current->mm = NULL; |
561 | membarrier_update_current_mm(NULL); |
562 | enter_lazy_tlb(mm, current); |
563 | local_irq_enable(); |
564 | task_unlock(current); |
565 | mmap_read_unlock(mm); |
566 | mm_update_next_owner(mm); |
567 | mmput(mm); |
568 | if (test_thread_flag(TIF_MEMDIE)) |
569 | exit_oom_victim(); |
570 | } |
571 | |
572 | static struct task_struct *find_alive_thread(struct task_struct *p) |
573 | { |
574 | struct task_struct *t; |
575 | |
576 | for_each_thread(p, t) { |
577 | if (!(t->flags & PF_EXITING)) |
578 | return t; |
579 | } |
580 | return NULL; |
581 | } |
582 | |
583 | static struct task_struct *find_child_reaper(struct task_struct *father, |
584 | struct list_head *dead) |
585 | __releases(&tasklist_lock) |
586 | __acquires(&tasklist_lock) |
587 | { |
588 | struct pid_namespace *pid_ns = task_active_pid_ns(tsk: father); |
589 | struct task_struct *reaper = pid_ns->child_reaper; |
590 | struct task_struct *p, *n; |
591 | |
592 | if (likely(reaper != father)) |
593 | return reaper; |
594 | |
595 | reaper = find_alive_thread(p: father); |
596 | if (reaper) { |
597 | pid_ns->child_reaper = reaper; |
598 | return reaper; |
599 | } |
600 | |
601 | write_unlock_irq(&tasklist_lock); |
602 | |
603 | list_for_each_entry_safe(p, n, dead, ptrace_entry) { |
604 | list_del_init(entry: &p->ptrace_entry); |
605 | release_task(p); |
606 | } |
607 | |
608 | zap_pid_ns_processes(pid_ns); |
609 | write_lock_irq(&tasklist_lock); |
610 | |
611 | return father; |
612 | } |
613 | |
614 | /* |
615 | * When we die, we re-parent all our children, and try to: |
616 | * 1. give them to another thread in our thread group, if such a member exists |
617 | * 2. give it to the first ancestor process which prctl'd itself as a |
618 | * child_subreaper for its children (like a service manager) |
619 | * 3. give it to the init process (PID 1) in our pid namespace |
620 | */ |
621 | static struct task_struct *find_new_reaper(struct task_struct *father, |
622 | struct task_struct *child_reaper) |
623 | { |
624 | struct task_struct *thread, *reaper; |
625 | |
626 | thread = find_alive_thread(p: father); |
627 | if (thread) |
628 | return thread; |
629 | |
630 | if (father->signal->has_child_subreaper) { |
631 | unsigned int ns_level = task_pid(task: father)->level; |
632 | /* |
633 | * Find the first ->is_child_subreaper ancestor in our pid_ns. |
634 | * We can't check reaper != child_reaper to ensure we do not |
635 | * cross the namespaces, the exiting parent could be injected |
636 | * by setns() + fork(). |
637 | * We check pid->level, this is slightly more efficient than |
638 | * task_active_pid_ns(reaper) != task_active_pid_ns(father). |
639 | */ |
640 | for (reaper = father->real_parent; |
641 | task_pid(task: reaper)->level == ns_level; |
642 | reaper = reaper->real_parent) { |
643 | if (reaper == &init_task) |
644 | break; |
645 | if (!reaper->signal->is_child_subreaper) |
646 | continue; |
647 | thread = find_alive_thread(p: reaper); |
648 | if (thread) |
649 | return thread; |
650 | } |
651 | } |
652 | |
653 | return child_reaper; |
654 | } |
655 | |
656 | /* |
657 | * Any that need to be release_task'd are put on the @dead list. |
658 | */ |
659 | static void reparent_leader(struct task_struct *father, struct task_struct *p, |
660 | struct list_head *dead) |
661 | { |
662 | if (unlikely(p->exit_state == EXIT_DEAD)) |
663 | return; |
664 | |
665 | /* We don't want people slaying init. */ |
666 | p->exit_signal = SIGCHLD; |
667 | |
668 | /* If it has exited notify the new parent about this child's death. */ |
669 | if (!p->ptrace && |
670 | p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { |
671 | if (do_notify_parent(p, p->exit_signal)) { |
672 | p->exit_state = EXIT_DEAD; |
673 | list_add(new: &p->ptrace_entry, head: dead); |
674 | } |
675 | } |
676 | |
677 | kill_orphaned_pgrp(tsk: p, parent: father); |
678 | } |
679 | |
680 | /* |
681 | * This does two things: |
682 | * |
683 | * A. Make init inherit all the child processes |
684 | * B. Check to see if any process groups have become orphaned |
685 | * as a result of our exiting, and if they have any stopped |
686 | * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) |
687 | */ |
688 | static void forget_original_parent(struct task_struct *father, |
689 | struct list_head *dead) |
690 | { |
691 | struct task_struct *p, *t, *reaper; |
692 | |
693 | if (unlikely(!list_empty(&father->ptraced))) |
694 | exit_ptrace(tracer: father, dead); |
695 | |
696 | /* Can drop and reacquire tasklist_lock */ |
697 | reaper = find_child_reaper(father, dead); |
698 | if (list_empty(head: &father->children)) |
699 | return; |
700 | |
701 | reaper = find_new_reaper(father, child_reaper: reaper); |
702 | list_for_each_entry(p, &father->children, sibling) { |
703 | for_each_thread(p, t) { |
704 | RCU_INIT_POINTER(t->real_parent, reaper); |
705 | BUG_ON((!t->ptrace) != (rcu_access_pointer(t->parent) == father)); |
706 | if (likely(!t->ptrace)) |
707 | t->parent = t->real_parent; |
708 | if (t->pdeath_signal) |
709 | group_send_sig_info(sig: t->pdeath_signal, |
710 | SEND_SIG_NOINFO, p: t, |
711 | type: PIDTYPE_TGID); |
712 | } |
713 | /* |
714 | * If this is a threaded reparent there is no need to |
715 | * notify anyone anything has happened. |
716 | */ |
717 | if (!same_thread_group(p1: reaper, p2: father)) |
718 | reparent_leader(father, p, dead); |
719 | } |
720 | list_splice_tail_init(list: &father->children, head: &reaper->children); |
721 | } |
722 | |
723 | /* |
724 | * Send signals to all our closest relatives so that they know |
725 | * to properly mourn us.. |
726 | */ |
727 | static void exit_notify(struct task_struct *tsk, int group_dead) |
728 | { |
729 | bool autoreap; |
730 | struct task_struct *p, *n; |
731 | LIST_HEAD(dead); |
732 | |
733 | write_lock_irq(&tasklist_lock); |
734 | forget_original_parent(father: tsk, dead: &dead); |
735 | |
736 | if (group_dead) |
737 | kill_orphaned_pgrp(tsk: tsk->group_leader, NULL); |
738 | |
739 | tsk->exit_state = EXIT_ZOMBIE; |
740 | if (unlikely(tsk->ptrace)) { |
741 | int sig = thread_group_leader(p: tsk) && |
742 | thread_group_empty(p: tsk) && |
743 | !ptrace_reparented(child: tsk) ? |
744 | tsk->exit_signal : SIGCHLD; |
745 | autoreap = do_notify_parent(tsk, sig); |
746 | } else if (thread_group_leader(p: tsk)) { |
747 | autoreap = thread_group_empty(p: tsk) && |
748 | do_notify_parent(tsk, tsk->exit_signal); |
749 | } else { |
750 | autoreap = true; |
751 | } |
752 | |
753 | if (autoreap) { |
754 | tsk->exit_state = EXIT_DEAD; |
755 | list_add(new: &tsk->ptrace_entry, head: &dead); |
756 | } |
757 | |
758 | /* mt-exec, de_thread() is waiting for group leader */ |
759 | if (unlikely(tsk->signal->notify_count < 0)) |
760 | wake_up_process(tsk: tsk->signal->group_exec_task); |
761 | write_unlock_irq(&tasklist_lock); |
762 | |
763 | list_for_each_entry_safe(p, n, &dead, ptrace_entry) { |
764 | list_del_init(entry: &p->ptrace_entry); |
765 | release_task(p); |
766 | } |
767 | } |
768 | |
769 | #ifdef CONFIG_DEBUG_STACK_USAGE |
770 | static void check_stack_usage(void) |
771 | { |
772 | static DEFINE_SPINLOCK(low_water_lock); |
773 | static int lowest_to_date = THREAD_SIZE; |
774 | unsigned long free; |
775 | |
776 | free = stack_not_used(current); |
777 | |
778 | if (free >= lowest_to_date) |
779 | return; |
780 | |
781 | spin_lock(lock: &low_water_lock); |
782 | if (free < lowest_to_date) { |
783 | pr_info("%s (%d) used greatest stack depth: %lu bytes left\n" , |
784 | current->comm, task_pid_nr(current), free); |
785 | lowest_to_date = free; |
786 | } |
787 | spin_unlock(lock: &low_water_lock); |
788 | } |
789 | #else |
790 | static inline void check_stack_usage(void) {} |
791 | #endif |
792 | |
793 | static void synchronize_group_exit(struct task_struct *tsk, long code) |
794 | { |
795 | struct sighand_struct *sighand = tsk->sighand; |
796 | struct signal_struct *signal = tsk->signal; |
797 | |
798 | spin_lock_irq(lock: &sighand->siglock); |
799 | signal->quick_threads--; |
800 | if ((signal->quick_threads == 0) && |
801 | !(signal->flags & SIGNAL_GROUP_EXIT)) { |
802 | signal->flags = SIGNAL_GROUP_EXIT; |
803 | signal->group_exit_code = code; |
804 | signal->group_stop_count = 0; |
805 | } |
806 | spin_unlock_irq(lock: &sighand->siglock); |
807 | } |
808 | |
809 | void __noreturn do_exit(long code) |
810 | { |
811 | struct task_struct *tsk = current; |
812 | int group_dead; |
813 | |
814 | WARN_ON(irqs_disabled()); |
815 | |
816 | synchronize_group_exit(tsk, code); |
817 | |
818 | WARN_ON(tsk->plug); |
819 | |
820 | kcov_task_exit(t: tsk); |
821 | kmsan_task_exit(task: tsk); |
822 | |
823 | coredump_task_exit(tsk); |
824 | ptrace_event(PTRACE_EVENT_EXIT, message: code); |
825 | user_events_exit(t: tsk); |
826 | |
827 | validate_creds_for_do_exit(tsk); |
828 | |
829 | io_uring_files_cancel(); |
830 | exit_signals(tsk); /* sets PF_EXITING */ |
831 | |
832 | acct_update_integrals(tsk); |
833 | group_dead = atomic_dec_and_test(v: &tsk->signal->live); |
834 | if (group_dead) { |
835 | /* |
836 | * If the last thread of global init has exited, panic |
837 | * immediately to get a useable coredump. |
838 | */ |
839 | if (unlikely(is_global_init(tsk))) |
840 | panic(fmt: "Attempted to kill init! exitcode=0x%08x\n" , |
841 | tsk->signal->group_exit_code ?: (int)code); |
842 | |
843 | #ifdef CONFIG_POSIX_TIMERS |
844 | hrtimer_cancel(timer: &tsk->signal->real_timer); |
845 | exit_itimers(tsk); |
846 | #endif |
847 | if (tsk->mm) |
848 | setmax_mm_hiwater_rss(maxrss: &tsk->signal->maxrss, mm: tsk->mm); |
849 | } |
850 | acct_collect(exitcode: code, group_dead); |
851 | if (group_dead) |
852 | tty_audit_exit(); |
853 | audit_free(task: tsk); |
854 | |
855 | tsk->exit_code = code; |
856 | taskstats_exit(tsk, group_dead); |
857 | |
858 | exit_mm(); |
859 | |
860 | if (group_dead) |
861 | acct_process(); |
862 | trace_sched_process_exit(p: tsk); |
863 | |
864 | exit_sem(tsk); |
865 | exit_shm(task: tsk); |
866 | exit_files(tsk); |
867 | exit_fs(tsk); |
868 | if (group_dead) |
869 | disassociate_ctty(priv: 1); |
870 | exit_task_namespaces(tsk); |
871 | exit_task_work(task: tsk); |
872 | exit_thread(tsk); |
873 | |
874 | /* |
875 | * Flush inherited counters to the parent - before the parent |
876 | * gets woken up by child-exit notifications. |
877 | * |
878 | * because of cgroup mode, must be called before cgroup_exit() |
879 | */ |
880 | perf_event_exit_task(child: tsk); |
881 | |
882 | sched_autogroup_exit_task(p: tsk); |
883 | cgroup_exit(p: tsk); |
884 | |
885 | /* |
886 | * FIXME: do that only when needed, using sched_exit tracepoint |
887 | */ |
888 | flush_ptrace_hw_breakpoint(tsk); |
889 | |
890 | exit_tasks_rcu_start(); |
891 | exit_notify(tsk, group_dead); |
892 | proc_exit_connector(task: tsk); |
893 | mpol_put_task_policy(tsk); |
894 | #ifdef CONFIG_FUTEX |
895 | if (unlikely(current->pi_state_cache)) |
896 | kfree(current->pi_state_cache); |
897 | #endif |
898 | /* |
899 | * Make sure we are holding no locks: |
900 | */ |
901 | debug_check_no_locks_held(); |
902 | |
903 | if (tsk->io_context) |
904 | exit_io_context(task: tsk); |
905 | |
906 | if (tsk->splice_pipe) |
907 | free_pipe_info(tsk->splice_pipe); |
908 | |
909 | if (tsk->task_frag.page) |
910 | put_page(page: tsk->task_frag.page); |
911 | |
912 | validate_creds_for_do_exit(tsk); |
913 | exit_task_stack_account(tsk); |
914 | |
915 | check_stack_usage(); |
916 | preempt_disable(); |
917 | if (tsk->nr_dirtied) |
918 | __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); |
919 | exit_rcu(); |
920 | exit_tasks_rcu_finish(); |
921 | |
922 | lockdep_free_task(task: tsk); |
923 | do_task_dead(); |
924 | } |
925 | |
926 | void __noreturn make_task_dead(int signr) |
927 | { |
928 | /* |
929 | * Take the task off the cpu after something catastrophic has |
930 | * happened. |
931 | * |
932 | * We can get here from a kernel oops, sometimes with preemption off. |
933 | * Start by checking for critical errors. |
934 | * Then fix up important state like USER_DS and preemption. |
935 | * Then do everything else. |
936 | */ |
937 | struct task_struct *tsk = current; |
938 | unsigned int limit; |
939 | |
940 | if (unlikely(in_interrupt())) |
941 | panic(fmt: "Aiee, killing interrupt handler!" ); |
942 | if (unlikely(!tsk->pid)) |
943 | panic(fmt: "Attempted to kill the idle task!" ); |
944 | |
945 | if (unlikely(irqs_disabled())) { |
946 | pr_info("note: %s[%d] exited with irqs disabled\n" , |
947 | current->comm, task_pid_nr(current)); |
948 | local_irq_enable(); |
949 | } |
950 | if (unlikely(in_atomic())) { |
951 | pr_info("note: %s[%d] exited with preempt_count %d\n" , |
952 | current->comm, task_pid_nr(current), |
953 | preempt_count()); |
954 | preempt_count_set(PREEMPT_ENABLED); |
955 | } |
956 | |
957 | /* |
958 | * Every time the system oopses, if the oops happens while a reference |
959 | * to an object was held, the reference leaks. |
960 | * If the oops doesn't also leak memory, repeated oopsing can cause |
961 | * reference counters to wrap around (if they're not using refcount_t). |
962 | * This means that repeated oopsing can make unexploitable-looking bugs |
963 | * exploitable through repeated oopsing. |
964 | * To make sure this can't happen, place an upper bound on how often the |
965 | * kernel may oops without panic(). |
966 | */ |
967 | limit = READ_ONCE(oops_limit); |
968 | if (atomic_inc_return(v: &oops_count) >= limit && limit) |
969 | panic(fmt: "Oopsed too often (kernel.oops_limit is %d)" , limit); |
970 | |
971 | /* |
972 | * We're taking recursive faults here in make_task_dead. Safest is to just |
973 | * leave this task alone and wait for reboot. |
974 | */ |
975 | if (unlikely(tsk->flags & PF_EXITING)) { |
976 | pr_alert("Fixing recursive fault but reboot is needed!\n" ); |
977 | futex_exit_recursive(tsk); |
978 | tsk->exit_state = EXIT_DEAD; |
979 | refcount_inc(r: &tsk->rcu_users); |
980 | do_task_dead(); |
981 | } |
982 | |
983 | do_exit(code: signr); |
984 | } |
985 | |
986 | SYSCALL_DEFINE1(exit, int, error_code) |
987 | { |
988 | do_exit(code: (error_code&0xff)<<8); |
989 | } |
990 | |
991 | /* |
992 | * Take down every thread in the group. This is called by fatal signals |
993 | * as well as by sys_exit_group (below). |
994 | */ |
995 | void __noreturn |
996 | do_group_exit(int exit_code) |
997 | { |
998 | struct signal_struct *sig = current->signal; |
999 | |
1000 | if (sig->flags & SIGNAL_GROUP_EXIT) |
1001 | exit_code = sig->group_exit_code; |
1002 | else if (sig->group_exec_task) |
1003 | exit_code = 0; |
1004 | else { |
1005 | struct sighand_struct *const sighand = current->sighand; |
1006 | |
1007 | spin_lock_irq(lock: &sighand->siglock); |
1008 | if (sig->flags & SIGNAL_GROUP_EXIT) |
1009 | /* Another thread got here before we took the lock. */ |
1010 | exit_code = sig->group_exit_code; |
1011 | else if (sig->group_exec_task) |
1012 | exit_code = 0; |
1013 | else { |
1014 | sig->group_exit_code = exit_code; |
1015 | sig->flags = SIGNAL_GROUP_EXIT; |
1016 | zap_other_threads(current); |
1017 | } |
1018 | spin_unlock_irq(lock: &sighand->siglock); |
1019 | } |
1020 | |
1021 | do_exit(code: exit_code); |
1022 | /* NOTREACHED */ |
1023 | } |
1024 | |
1025 | /* |
1026 | * this kills every thread in the thread group. Note that any externally |
1027 | * wait4()-ing process will get the correct exit code - even if this |
1028 | * thread is not the thread group leader. |
1029 | */ |
1030 | SYSCALL_DEFINE1(exit_group, int, error_code) |
1031 | { |
1032 | do_group_exit(exit_code: (error_code & 0xff) << 8); |
1033 | /* NOTREACHED */ |
1034 | return 0; |
1035 | } |
1036 | |
1037 | static int eligible_pid(struct wait_opts *wo, struct task_struct *p) |
1038 | { |
1039 | return wo->wo_type == PIDTYPE_MAX || |
1040 | task_pid_type(task: p, type: wo->wo_type) == wo->wo_pid; |
1041 | } |
1042 | |
1043 | static int |
1044 | eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p) |
1045 | { |
1046 | if (!eligible_pid(wo, p)) |
1047 | return 0; |
1048 | |
1049 | /* |
1050 | * Wait for all children (clone and not) if __WALL is set or |
1051 | * if it is traced by us. |
1052 | */ |
1053 | if (ptrace || (wo->wo_flags & __WALL)) |
1054 | return 1; |
1055 | |
1056 | /* |
1057 | * Otherwise, wait for clone children *only* if __WCLONE is set; |
1058 | * otherwise, wait for non-clone children *only*. |
1059 | * |
1060 | * Note: a "clone" child here is one that reports to its parent |
1061 | * using a signal other than SIGCHLD, or a non-leader thread which |
1062 | * we can only see if it is traced by us. |
1063 | */ |
1064 | if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) |
1065 | return 0; |
1066 | |
1067 | return 1; |
1068 | } |
1069 | |
1070 | /* |
1071 | * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold |
1072 | * read_lock(&tasklist_lock) on entry. If we return zero, we still hold |
1073 | * the lock and this task is uninteresting. If we return nonzero, we have |
1074 | * released the lock and the system call should return. |
1075 | */ |
1076 | static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) |
1077 | { |
1078 | int state, status; |
1079 | pid_t pid = task_pid_vnr(tsk: p); |
1080 | uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
1081 | struct waitid_info *infop; |
1082 | |
1083 | if (!likely(wo->wo_flags & WEXITED)) |
1084 | return 0; |
1085 | |
1086 | if (unlikely(wo->wo_flags & WNOWAIT)) { |
1087 | status = (p->signal->flags & SIGNAL_GROUP_EXIT) |
1088 | ? p->signal->group_exit_code : p->exit_code; |
1089 | get_task_struct(t: p); |
1090 | read_unlock(&tasklist_lock); |
1091 | sched_annotate_sleep(); |
1092 | if (wo->wo_rusage) |
1093 | getrusage(p, RUSAGE_BOTH, ru: wo->wo_rusage); |
1094 | put_task_struct(t: p); |
1095 | goto out_info; |
1096 | } |
1097 | /* |
1098 | * Move the task's state to DEAD/TRACE, only one thread can do this. |
1099 | */ |
1100 | state = (ptrace_reparented(child: p) && thread_group_leader(p)) ? |
1101 | EXIT_TRACE : EXIT_DEAD; |
1102 | if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) |
1103 | return 0; |
1104 | /* |
1105 | * We own this thread, nobody else can reap it. |
1106 | */ |
1107 | read_unlock(&tasklist_lock); |
1108 | sched_annotate_sleep(); |
1109 | |
1110 | /* |
1111 | * Check thread_group_leader() to exclude the traced sub-threads. |
1112 | */ |
1113 | if (state == EXIT_DEAD && thread_group_leader(p)) { |
1114 | struct signal_struct *sig = p->signal; |
1115 | struct signal_struct *psig = current->signal; |
1116 | unsigned long ; |
1117 | u64 tgutime, tgstime; |
1118 | |
1119 | /* |
1120 | * The resource counters for the group leader are in its |
1121 | * own task_struct. Those for dead threads in the group |
1122 | * are in its signal_struct, as are those for the child |
1123 | * processes it has previously reaped. All these |
1124 | * accumulate in the parent's signal_struct c* fields. |
1125 | * |
1126 | * We don't bother to take a lock here to protect these |
1127 | * p->signal fields because the whole thread group is dead |
1128 | * and nobody can change them. |
1129 | * |
1130 | * psig->stats_lock also protects us from our sub-threads |
1131 | * which can reap other children at the same time. Until |
1132 | * we change k_getrusage()-like users to rely on this lock |
1133 | * we have to take ->siglock as well. |
1134 | * |
1135 | * We use thread_group_cputime_adjusted() to get times for |
1136 | * the thread group, which consolidates times for all threads |
1137 | * in the group including the group leader. |
1138 | */ |
1139 | thread_group_cputime_adjusted(p, ut: &tgutime, st: &tgstime); |
1140 | spin_lock_irq(lock: ¤t->sighand->siglock); |
1141 | write_seqlock(sl: &psig->stats_lock); |
1142 | psig->cutime += tgutime + sig->cutime; |
1143 | psig->cstime += tgstime + sig->cstime; |
1144 | psig->cgtime += task_gtime(t: p) + sig->gtime + sig->cgtime; |
1145 | psig->cmin_flt += |
1146 | p->min_flt + sig->min_flt + sig->cmin_flt; |
1147 | psig->cmaj_flt += |
1148 | p->maj_flt + sig->maj_flt + sig->cmaj_flt; |
1149 | psig->cnvcsw += |
1150 | p->nvcsw + sig->nvcsw + sig->cnvcsw; |
1151 | psig->cnivcsw += |
1152 | p->nivcsw + sig->nivcsw + sig->cnivcsw; |
1153 | psig->cinblock += |
1154 | task_io_get_inblock(p) + |
1155 | sig->inblock + sig->cinblock; |
1156 | psig->coublock += |
1157 | task_io_get_oublock(p) + |
1158 | sig->oublock + sig->coublock; |
1159 | maxrss = max(sig->maxrss, sig->cmaxrss); |
1160 | if (psig->cmaxrss < maxrss) |
1161 | psig->cmaxrss = maxrss; |
1162 | task_io_accounting_add(dst: &psig->ioac, src: &p->ioac); |
1163 | task_io_accounting_add(dst: &psig->ioac, src: &sig->ioac); |
1164 | write_sequnlock(sl: &psig->stats_lock); |
1165 | spin_unlock_irq(lock: ¤t->sighand->siglock); |
1166 | } |
1167 | |
1168 | if (wo->wo_rusage) |
1169 | getrusage(p, RUSAGE_BOTH, ru: wo->wo_rusage); |
1170 | status = (p->signal->flags & SIGNAL_GROUP_EXIT) |
1171 | ? p->signal->group_exit_code : p->exit_code; |
1172 | wo->wo_stat = status; |
1173 | |
1174 | if (state == EXIT_TRACE) { |
1175 | write_lock_irq(&tasklist_lock); |
1176 | /* We dropped tasklist, ptracer could die and untrace */ |
1177 | ptrace_unlink(child: p); |
1178 | |
1179 | /* If parent wants a zombie, don't release it now */ |
1180 | state = EXIT_ZOMBIE; |
1181 | if (do_notify_parent(p, p->exit_signal)) |
1182 | state = EXIT_DEAD; |
1183 | p->exit_state = state; |
1184 | write_unlock_irq(&tasklist_lock); |
1185 | } |
1186 | if (state == EXIT_DEAD) |
1187 | release_task(p); |
1188 | |
1189 | out_info: |
1190 | infop = wo->wo_info; |
1191 | if (infop) { |
1192 | if ((status & 0x7f) == 0) { |
1193 | infop->cause = CLD_EXITED; |
1194 | infop->status = status >> 8; |
1195 | } else { |
1196 | infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; |
1197 | infop->status = status & 0x7f; |
1198 | } |
1199 | infop->pid = pid; |
1200 | infop->uid = uid; |
1201 | } |
1202 | |
1203 | return pid; |
1204 | } |
1205 | |
1206 | static int *task_stopped_code(struct task_struct *p, bool ptrace) |
1207 | { |
1208 | if (ptrace) { |
1209 | if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING)) |
1210 | return &p->exit_code; |
1211 | } else { |
1212 | if (p->signal->flags & SIGNAL_STOP_STOPPED) |
1213 | return &p->signal->group_exit_code; |
1214 | } |
1215 | return NULL; |
1216 | } |
1217 | |
1218 | /** |
1219 | * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED |
1220 | * @wo: wait options |
1221 | * @ptrace: is the wait for ptrace |
1222 | * @p: task to wait for |
1223 | * |
1224 | * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED. |
1225 | * |
1226 | * CONTEXT: |
1227 | * read_lock(&tasklist_lock), which is released if return value is |
1228 | * non-zero. Also, grabs and releases @p->sighand->siglock. |
1229 | * |
1230 | * RETURNS: |
1231 | * 0 if wait condition didn't exist and search for other wait conditions |
1232 | * should continue. Non-zero return, -errno on failure and @p's pid on |
1233 | * success, implies that tasklist_lock is released and wait condition |
1234 | * search should terminate. |
1235 | */ |
1236 | static int wait_task_stopped(struct wait_opts *wo, |
1237 | int ptrace, struct task_struct *p) |
1238 | { |
1239 | struct waitid_info *infop; |
1240 | int exit_code, *p_code, why; |
1241 | uid_t uid = 0; /* unneeded, required by compiler */ |
1242 | pid_t pid; |
1243 | |
1244 | /* |
1245 | * Traditionally we see ptrace'd stopped tasks regardless of options. |
1246 | */ |
1247 | if (!ptrace && !(wo->wo_flags & WUNTRACED)) |
1248 | return 0; |
1249 | |
1250 | if (!task_stopped_code(p, ptrace)) |
1251 | return 0; |
1252 | |
1253 | exit_code = 0; |
1254 | spin_lock_irq(lock: &p->sighand->siglock); |
1255 | |
1256 | p_code = task_stopped_code(p, ptrace); |
1257 | if (unlikely(!p_code)) |
1258 | goto unlock_sig; |
1259 | |
1260 | exit_code = *p_code; |
1261 | if (!exit_code) |
1262 | goto unlock_sig; |
1263 | |
1264 | if (!unlikely(wo->wo_flags & WNOWAIT)) |
1265 | *p_code = 0; |
1266 | |
1267 | uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
1268 | unlock_sig: |
1269 | spin_unlock_irq(lock: &p->sighand->siglock); |
1270 | if (!exit_code) |
1271 | return 0; |
1272 | |
1273 | /* |
1274 | * Now we are pretty sure this task is interesting. |
1275 | * Make sure it doesn't get reaped out from under us while we |
1276 | * give up the lock and then examine it below. We don't want to |
1277 | * keep holding onto the tasklist_lock while we call getrusage and |
1278 | * possibly take page faults for user memory. |
1279 | */ |
1280 | get_task_struct(t: p); |
1281 | pid = task_pid_vnr(tsk: p); |
1282 | why = ptrace ? CLD_TRAPPED : CLD_STOPPED; |
1283 | read_unlock(&tasklist_lock); |
1284 | sched_annotate_sleep(); |
1285 | if (wo->wo_rusage) |
1286 | getrusage(p, RUSAGE_BOTH, ru: wo->wo_rusage); |
1287 | put_task_struct(t: p); |
1288 | |
1289 | if (likely(!(wo->wo_flags & WNOWAIT))) |
1290 | wo->wo_stat = (exit_code << 8) | 0x7f; |
1291 | |
1292 | infop = wo->wo_info; |
1293 | if (infop) { |
1294 | infop->cause = why; |
1295 | infop->status = exit_code; |
1296 | infop->pid = pid; |
1297 | infop->uid = uid; |
1298 | } |
1299 | return pid; |
1300 | } |
1301 | |
1302 | /* |
1303 | * Handle do_wait work for one task in a live, non-stopped state. |
1304 | * read_lock(&tasklist_lock) on entry. If we return zero, we still hold |
1305 | * the lock and this task is uninteresting. If we return nonzero, we have |
1306 | * released the lock and the system call should return. |
1307 | */ |
1308 | static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) |
1309 | { |
1310 | struct waitid_info *infop; |
1311 | pid_t pid; |
1312 | uid_t uid; |
1313 | |
1314 | if (!unlikely(wo->wo_flags & WCONTINUED)) |
1315 | return 0; |
1316 | |
1317 | if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) |
1318 | return 0; |
1319 | |
1320 | spin_lock_irq(lock: &p->sighand->siglock); |
1321 | /* Re-check with the lock held. */ |
1322 | if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { |
1323 | spin_unlock_irq(lock: &p->sighand->siglock); |
1324 | return 0; |
1325 | } |
1326 | if (!unlikely(wo->wo_flags & WNOWAIT)) |
1327 | p->signal->flags &= ~SIGNAL_STOP_CONTINUED; |
1328 | uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
1329 | spin_unlock_irq(lock: &p->sighand->siglock); |
1330 | |
1331 | pid = task_pid_vnr(tsk: p); |
1332 | get_task_struct(t: p); |
1333 | read_unlock(&tasklist_lock); |
1334 | sched_annotate_sleep(); |
1335 | if (wo->wo_rusage) |
1336 | getrusage(p, RUSAGE_BOTH, ru: wo->wo_rusage); |
1337 | put_task_struct(t: p); |
1338 | |
1339 | infop = wo->wo_info; |
1340 | if (!infop) { |
1341 | wo->wo_stat = 0xffff; |
1342 | } else { |
1343 | infop->cause = CLD_CONTINUED; |
1344 | infop->pid = pid; |
1345 | infop->uid = uid; |
1346 | infop->status = SIGCONT; |
1347 | } |
1348 | return pid; |
1349 | } |
1350 | |
1351 | /* |
1352 | * Consider @p for a wait by @parent. |
1353 | * |
1354 | * -ECHILD should be in ->notask_error before the first call. |
1355 | * Returns nonzero for a final return, when we have unlocked tasklist_lock. |
1356 | * Returns zero if the search for a child should continue; |
1357 | * then ->notask_error is 0 if @p is an eligible child, |
1358 | * or still -ECHILD. |
1359 | */ |
1360 | static int wait_consider_task(struct wait_opts *wo, int ptrace, |
1361 | struct task_struct *p) |
1362 | { |
1363 | /* |
1364 | * We can race with wait_task_zombie() from another thread. |
1365 | * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition |
1366 | * can't confuse the checks below. |
1367 | */ |
1368 | int exit_state = READ_ONCE(p->exit_state); |
1369 | int ret; |
1370 | |
1371 | if (unlikely(exit_state == EXIT_DEAD)) |
1372 | return 0; |
1373 | |
1374 | ret = eligible_child(wo, ptrace, p); |
1375 | if (!ret) |
1376 | return ret; |
1377 | |
1378 | if (unlikely(exit_state == EXIT_TRACE)) { |
1379 | /* |
1380 | * ptrace == 0 means we are the natural parent. In this case |
1381 | * we should clear notask_error, debugger will notify us. |
1382 | */ |
1383 | if (likely(!ptrace)) |
1384 | wo->notask_error = 0; |
1385 | return 0; |
1386 | } |
1387 | |
1388 | if (likely(!ptrace) && unlikely(p->ptrace)) { |
1389 | /* |
1390 | * If it is traced by its real parent's group, just pretend |
1391 | * the caller is ptrace_do_wait() and reap this child if it |
1392 | * is zombie. |
1393 | * |
1394 | * This also hides group stop state from real parent; otherwise |
1395 | * a single stop can be reported twice as group and ptrace stop. |
1396 | * If a ptracer wants to distinguish these two events for its |
1397 | * own children it should create a separate process which takes |
1398 | * the role of real parent. |
1399 | */ |
1400 | if (!ptrace_reparented(child: p)) |
1401 | ptrace = 1; |
1402 | } |
1403 | |
1404 | /* slay zombie? */ |
1405 | if (exit_state == EXIT_ZOMBIE) { |
1406 | /* we don't reap group leaders with subthreads */ |
1407 | if (!delay_group_leader(p)) { |
1408 | /* |
1409 | * A zombie ptracee is only visible to its ptracer. |
1410 | * Notification and reaping will be cascaded to the |
1411 | * real parent when the ptracer detaches. |
1412 | */ |
1413 | if (unlikely(ptrace) || likely(!p->ptrace)) |
1414 | return wait_task_zombie(wo, p); |
1415 | } |
1416 | |
1417 | /* |
1418 | * Allow access to stopped/continued state via zombie by |
1419 | * falling through. Clearing of notask_error is complex. |
1420 | * |
1421 | * When !@ptrace: |
1422 | * |
1423 | * If WEXITED is set, notask_error should naturally be |
1424 | * cleared. If not, subset of WSTOPPED|WCONTINUED is set, |
1425 | * so, if there are live subthreads, there are events to |
1426 | * wait for. If all subthreads are dead, it's still safe |
1427 | * to clear - this function will be called again in finite |
1428 | * amount time once all the subthreads are released and |
1429 | * will then return without clearing. |
1430 | * |
1431 | * When @ptrace: |
1432 | * |
1433 | * Stopped state is per-task and thus can't change once the |
1434 | * target task dies. Only continued and exited can happen. |
1435 | * Clear notask_error if WCONTINUED | WEXITED. |
1436 | */ |
1437 | if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED))) |
1438 | wo->notask_error = 0; |
1439 | } else { |
1440 | /* |
1441 | * @p is alive and it's gonna stop, continue or exit, so |
1442 | * there always is something to wait for. |
1443 | */ |
1444 | wo->notask_error = 0; |
1445 | } |
1446 | |
1447 | /* |
1448 | * Wait for stopped. Depending on @ptrace, different stopped state |
1449 | * is used and the two don't interact with each other. |
1450 | */ |
1451 | ret = wait_task_stopped(wo, ptrace, p); |
1452 | if (ret) |
1453 | return ret; |
1454 | |
1455 | /* |
1456 | * Wait for continued. There's only one continued state and the |
1457 | * ptracer can consume it which can confuse the real parent. Don't |
1458 | * use WCONTINUED from ptracer. You don't need or want it. |
1459 | */ |
1460 | return wait_task_continued(wo, p); |
1461 | } |
1462 | |
1463 | /* |
1464 | * Do the work of do_wait() for one thread in the group, @tsk. |
1465 | * |
1466 | * -ECHILD should be in ->notask_error before the first call. |
1467 | * Returns nonzero for a final return, when we have unlocked tasklist_lock. |
1468 | * Returns zero if the search for a child should continue; then |
1469 | * ->notask_error is 0 if there were any eligible children, |
1470 | * or still -ECHILD. |
1471 | */ |
1472 | static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) |
1473 | { |
1474 | struct task_struct *p; |
1475 | |
1476 | list_for_each_entry(p, &tsk->children, sibling) { |
1477 | int ret = wait_consider_task(wo, ptrace: 0, p); |
1478 | |
1479 | if (ret) |
1480 | return ret; |
1481 | } |
1482 | |
1483 | return 0; |
1484 | } |
1485 | |
1486 | static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) |
1487 | { |
1488 | struct task_struct *p; |
1489 | |
1490 | list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { |
1491 | int ret = wait_consider_task(wo, ptrace: 1, p); |
1492 | |
1493 | if (ret) |
1494 | return ret; |
1495 | } |
1496 | |
1497 | return 0; |
1498 | } |
1499 | |
1500 | bool pid_child_should_wake(struct wait_opts *wo, struct task_struct *p) |
1501 | { |
1502 | if (!eligible_pid(wo, p)) |
1503 | return false; |
1504 | |
1505 | if ((wo->wo_flags & __WNOTHREAD) && wo->child_wait.private != p->parent) |
1506 | return false; |
1507 | |
1508 | return true; |
1509 | } |
1510 | |
1511 | static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode, |
1512 | int sync, void *key) |
1513 | { |
1514 | struct wait_opts *wo = container_of(wait, struct wait_opts, |
1515 | child_wait); |
1516 | struct task_struct *p = key; |
1517 | |
1518 | if (pid_child_should_wake(wo, p)) |
1519 | return default_wake_function(wq_entry: wait, mode, flags: sync, key); |
1520 | |
1521 | return 0; |
1522 | } |
1523 | |
1524 | void __wake_up_parent(struct task_struct *p, struct task_struct *parent) |
1525 | { |
1526 | __wake_up_sync_key(wq_head: &parent->signal->wait_chldexit, |
1527 | TASK_INTERRUPTIBLE, key: p); |
1528 | } |
1529 | |
1530 | static bool is_effectively_child(struct wait_opts *wo, bool ptrace, |
1531 | struct task_struct *target) |
1532 | { |
1533 | struct task_struct *parent = |
1534 | !ptrace ? target->real_parent : target->parent; |
1535 | |
1536 | return current == parent || (!(wo->wo_flags & __WNOTHREAD) && |
1537 | same_thread_group(current, p2: parent)); |
1538 | } |
1539 | |
1540 | /* |
1541 | * Optimization for waiting on PIDTYPE_PID. No need to iterate through child |
1542 | * and tracee lists to find the target task. |
1543 | */ |
1544 | static int do_wait_pid(struct wait_opts *wo) |
1545 | { |
1546 | bool ptrace; |
1547 | struct task_struct *target; |
1548 | int retval; |
1549 | |
1550 | ptrace = false; |
1551 | target = pid_task(pid: wo->wo_pid, PIDTYPE_TGID); |
1552 | if (target && is_effectively_child(wo, ptrace, target)) { |
1553 | retval = wait_consider_task(wo, ptrace, p: target); |
1554 | if (retval) |
1555 | return retval; |
1556 | } |
1557 | |
1558 | ptrace = true; |
1559 | target = pid_task(pid: wo->wo_pid, PIDTYPE_PID); |
1560 | if (target && target->ptrace && |
1561 | is_effectively_child(wo, ptrace, target)) { |
1562 | retval = wait_consider_task(wo, ptrace, p: target); |
1563 | if (retval) |
1564 | return retval; |
1565 | } |
1566 | |
1567 | return 0; |
1568 | } |
1569 | |
1570 | long __do_wait(struct wait_opts *wo) |
1571 | { |
1572 | long retval; |
1573 | |
1574 | /* |
1575 | * If there is nothing that can match our criteria, just get out. |
1576 | * We will clear ->notask_error to zero if we see any child that |
1577 | * might later match our criteria, even if we are not able to reap |
1578 | * it yet. |
1579 | */ |
1580 | wo->notask_error = -ECHILD; |
1581 | if ((wo->wo_type < PIDTYPE_MAX) && |
1582 | (!wo->wo_pid || !pid_has_task(pid: wo->wo_pid, type: wo->wo_type))) |
1583 | goto notask; |
1584 | |
1585 | read_lock(&tasklist_lock); |
1586 | |
1587 | if (wo->wo_type == PIDTYPE_PID) { |
1588 | retval = do_wait_pid(wo); |
1589 | if (retval) |
1590 | return retval; |
1591 | } else { |
1592 | struct task_struct *tsk = current; |
1593 | |
1594 | do { |
1595 | retval = do_wait_thread(wo, tsk); |
1596 | if (retval) |
1597 | return retval; |
1598 | |
1599 | retval = ptrace_do_wait(wo, tsk); |
1600 | if (retval) |
1601 | return retval; |
1602 | |
1603 | if (wo->wo_flags & __WNOTHREAD) |
1604 | break; |
1605 | } while_each_thread(current, tsk); |
1606 | } |
1607 | read_unlock(&tasklist_lock); |
1608 | |
1609 | notask: |
1610 | retval = wo->notask_error; |
1611 | if (!retval && !(wo->wo_flags & WNOHANG)) |
1612 | return -ERESTARTSYS; |
1613 | |
1614 | return retval; |
1615 | } |
1616 | |
1617 | static long do_wait(struct wait_opts *wo) |
1618 | { |
1619 | int retval; |
1620 | |
1621 | trace_sched_process_wait(pid: wo->wo_pid); |
1622 | |
1623 | init_waitqueue_func_entry(wq_entry: &wo->child_wait, func: child_wait_callback); |
1624 | wo->child_wait.private = current; |
1625 | add_wait_queue(wq_head: ¤t->signal->wait_chldexit, wq_entry: &wo->child_wait); |
1626 | |
1627 | do { |
1628 | set_current_state(TASK_INTERRUPTIBLE); |
1629 | retval = __do_wait(wo); |
1630 | if (retval != -ERESTARTSYS) |
1631 | break; |
1632 | if (signal_pending(current)) |
1633 | break; |
1634 | schedule(); |
1635 | } while (1); |
1636 | |
1637 | __set_current_state(TASK_RUNNING); |
1638 | remove_wait_queue(wq_head: ¤t->signal->wait_chldexit, wq_entry: &wo->child_wait); |
1639 | return retval; |
1640 | } |
1641 | |
1642 | int kernel_waitid_prepare(struct wait_opts *wo, int which, pid_t upid, |
1643 | struct waitid_info *infop, int options, |
1644 | struct rusage *ru) |
1645 | { |
1646 | unsigned int f_flags = 0; |
1647 | struct pid *pid = NULL; |
1648 | enum pid_type type; |
1649 | |
1650 | if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED| |
1651 | __WNOTHREAD|__WCLONE|__WALL)) |
1652 | return -EINVAL; |
1653 | if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) |
1654 | return -EINVAL; |
1655 | |
1656 | switch (which) { |
1657 | case P_ALL: |
1658 | type = PIDTYPE_MAX; |
1659 | break; |
1660 | case P_PID: |
1661 | type = PIDTYPE_PID; |
1662 | if (upid <= 0) |
1663 | return -EINVAL; |
1664 | |
1665 | pid = find_get_pid(nr: upid); |
1666 | break; |
1667 | case P_PGID: |
1668 | type = PIDTYPE_PGID; |
1669 | if (upid < 0) |
1670 | return -EINVAL; |
1671 | |
1672 | if (upid) |
1673 | pid = find_get_pid(nr: upid); |
1674 | else |
1675 | pid = get_task_pid(current, type: PIDTYPE_PGID); |
1676 | break; |
1677 | case P_PIDFD: |
1678 | type = PIDTYPE_PID; |
1679 | if (upid < 0) |
1680 | return -EINVAL; |
1681 | |
1682 | pid = pidfd_get_pid(fd: upid, flags: &f_flags); |
1683 | if (IS_ERR(ptr: pid)) |
1684 | return PTR_ERR(ptr: pid); |
1685 | |
1686 | break; |
1687 | default: |
1688 | return -EINVAL; |
1689 | } |
1690 | |
1691 | wo->wo_type = type; |
1692 | wo->wo_pid = pid; |
1693 | wo->wo_flags = options; |
1694 | wo->wo_info = infop; |
1695 | wo->wo_rusage = ru; |
1696 | if (f_flags & O_NONBLOCK) |
1697 | wo->wo_flags |= WNOHANG; |
1698 | |
1699 | return 0; |
1700 | } |
1701 | |
1702 | static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, |
1703 | int options, struct rusage *ru) |
1704 | { |
1705 | struct wait_opts wo; |
1706 | long ret; |
1707 | |
1708 | ret = kernel_waitid_prepare(wo: &wo, which, upid, infop, options, ru); |
1709 | if (ret) |
1710 | return ret; |
1711 | |
1712 | ret = do_wait(wo: &wo); |
1713 | if (!ret && !(options & WNOHANG) && (wo.wo_flags & WNOHANG)) |
1714 | ret = -EAGAIN; |
1715 | |
1716 | put_pid(pid: wo.wo_pid); |
1717 | return ret; |
1718 | } |
1719 | |
1720 | SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, |
1721 | infop, int, options, struct rusage __user *, ru) |
1722 | { |
1723 | struct rusage r; |
1724 | struct waitid_info info = {.status = 0}; |
1725 | long err = kernel_waitid(which, upid, infop: &info, options, ru: ru ? &r : NULL); |
1726 | int signo = 0; |
1727 | |
1728 | if (err > 0) { |
1729 | signo = SIGCHLD; |
1730 | err = 0; |
1731 | if (ru && copy_to_user(to: ru, from: &r, n: sizeof(struct rusage))) |
1732 | return -EFAULT; |
1733 | } |
1734 | if (!infop) |
1735 | return err; |
1736 | |
1737 | if (!user_write_access_begin(infop, sizeof(*infop))) |
1738 | return -EFAULT; |
1739 | |
1740 | unsafe_put_user(signo, &infop->si_signo, Efault); |
1741 | unsafe_put_user(0, &infop->si_errno, Efault); |
1742 | unsafe_put_user(info.cause, &infop->si_code, Efault); |
1743 | unsafe_put_user(info.pid, &infop->si_pid, Efault); |
1744 | unsafe_put_user(info.uid, &infop->si_uid, Efault); |
1745 | unsafe_put_user(info.status, &infop->si_status, Efault); |
1746 | user_write_access_end(); |
1747 | return err; |
1748 | Efault: |
1749 | user_write_access_end(); |
1750 | return -EFAULT; |
1751 | } |
1752 | |
1753 | long kernel_wait4(pid_t upid, int __user *stat_addr, int options, |
1754 | struct rusage *ru) |
1755 | { |
1756 | struct wait_opts wo; |
1757 | struct pid *pid = NULL; |
1758 | enum pid_type type; |
1759 | long ret; |
1760 | |
1761 | if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| |
1762 | __WNOTHREAD|__WCLONE|__WALL)) |
1763 | return -EINVAL; |
1764 | |
1765 | /* -INT_MIN is not defined */ |
1766 | if (upid == INT_MIN) |
1767 | return -ESRCH; |
1768 | |
1769 | if (upid == -1) |
1770 | type = PIDTYPE_MAX; |
1771 | else if (upid < 0) { |
1772 | type = PIDTYPE_PGID; |
1773 | pid = find_get_pid(nr: -upid); |
1774 | } else if (upid == 0) { |
1775 | type = PIDTYPE_PGID; |
1776 | pid = get_task_pid(current, type: PIDTYPE_PGID); |
1777 | } else /* upid > 0 */ { |
1778 | type = PIDTYPE_PID; |
1779 | pid = find_get_pid(nr: upid); |
1780 | } |
1781 | |
1782 | wo.wo_type = type; |
1783 | wo.wo_pid = pid; |
1784 | wo.wo_flags = options | WEXITED; |
1785 | wo.wo_info = NULL; |
1786 | wo.wo_stat = 0; |
1787 | wo.wo_rusage = ru; |
1788 | ret = do_wait(wo: &wo); |
1789 | put_pid(pid); |
1790 | if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr)) |
1791 | ret = -EFAULT; |
1792 | |
1793 | return ret; |
1794 | } |
1795 | |
1796 | int kernel_wait(pid_t pid, int *stat) |
1797 | { |
1798 | struct wait_opts wo = { |
1799 | .wo_type = PIDTYPE_PID, |
1800 | .wo_pid = find_get_pid(nr: pid), |
1801 | .wo_flags = WEXITED, |
1802 | }; |
1803 | int ret; |
1804 | |
1805 | ret = do_wait(wo: &wo); |
1806 | if (ret > 0 && wo.wo_stat) |
1807 | *stat = wo.wo_stat; |
1808 | put_pid(pid: wo.wo_pid); |
1809 | return ret; |
1810 | } |
1811 | |
1812 | SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, |
1813 | int, options, struct rusage __user *, ru) |
1814 | { |
1815 | struct rusage r; |
1816 | long err = kernel_wait4(upid, stat_addr, options, ru: ru ? &r : NULL); |
1817 | |
1818 | if (err > 0) { |
1819 | if (ru && copy_to_user(to: ru, from: &r, n: sizeof(struct rusage))) |
1820 | return -EFAULT; |
1821 | } |
1822 | return err; |
1823 | } |
1824 | |
1825 | #ifdef __ARCH_WANT_SYS_WAITPID |
1826 | |
1827 | /* |
1828 | * sys_waitpid() remains for compatibility. waitpid() should be |
1829 | * implemented by calling sys_wait4() from libc.a. |
1830 | */ |
1831 | SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) |
1832 | { |
1833 | return kernel_wait4(upid: pid, stat_addr, options, NULL); |
1834 | } |
1835 | |
1836 | #endif |
1837 | |
1838 | #ifdef CONFIG_COMPAT |
1839 | COMPAT_SYSCALL_DEFINE4(wait4, |
1840 | compat_pid_t, pid, |
1841 | compat_uint_t __user *, stat_addr, |
1842 | int, options, |
1843 | struct compat_rusage __user *, ru) |
1844 | { |
1845 | struct rusage r; |
1846 | long err = kernel_wait4(upid: pid, stat_addr, options, ru: ru ? &r : NULL); |
1847 | if (err > 0) { |
1848 | if (ru && put_compat_rusage(&r, ru)) |
1849 | return -EFAULT; |
1850 | } |
1851 | return err; |
1852 | } |
1853 | |
1854 | COMPAT_SYSCALL_DEFINE5(waitid, |
1855 | int, which, compat_pid_t, pid, |
1856 | struct compat_siginfo __user *, infop, int, options, |
1857 | struct compat_rusage __user *, uru) |
1858 | { |
1859 | struct rusage ru; |
1860 | struct waitid_info info = {.status = 0}; |
1861 | long err = kernel_waitid(which, upid: pid, infop: &info, options, ru: uru ? &ru : NULL); |
1862 | int signo = 0; |
1863 | if (err > 0) { |
1864 | signo = SIGCHLD; |
1865 | err = 0; |
1866 | if (uru) { |
1867 | /* kernel_waitid() overwrites everything in ru */ |
1868 | if (COMPAT_USE_64BIT_TIME) |
1869 | err = copy_to_user(to: uru, from: &ru, n: sizeof(ru)); |
1870 | else |
1871 | err = put_compat_rusage(&ru, uru); |
1872 | if (err) |
1873 | return -EFAULT; |
1874 | } |
1875 | } |
1876 | |
1877 | if (!infop) |
1878 | return err; |
1879 | |
1880 | if (!user_write_access_begin(infop, sizeof(*infop))) |
1881 | return -EFAULT; |
1882 | |
1883 | unsafe_put_user(signo, &infop->si_signo, Efault); |
1884 | unsafe_put_user(0, &infop->si_errno, Efault); |
1885 | unsafe_put_user(info.cause, &infop->si_code, Efault); |
1886 | unsafe_put_user(info.pid, &infop->si_pid, Efault); |
1887 | unsafe_put_user(info.uid, &infop->si_uid, Efault); |
1888 | unsafe_put_user(info.status, &infop->si_status, Efault); |
1889 | user_write_access_end(); |
1890 | return err; |
1891 | Efault: |
1892 | user_write_access_end(); |
1893 | return -EFAULT; |
1894 | } |
1895 | #endif |
1896 | |
1897 | /** |
1898 | * thread_group_exited - check that a thread group has exited |
1899 | * @pid: tgid of thread group to be checked. |
1900 | * |
1901 | * Test if the thread group represented by tgid has exited (all |
1902 | * threads are zombies, dead or completely gone). |
1903 | * |
1904 | * Return: true if the thread group has exited. false otherwise. |
1905 | */ |
1906 | bool thread_group_exited(struct pid *pid) |
1907 | { |
1908 | struct task_struct *task; |
1909 | bool exited; |
1910 | |
1911 | rcu_read_lock(); |
1912 | task = pid_task(pid, PIDTYPE_PID); |
1913 | exited = !task || |
1914 | (READ_ONCE(task->exit_state) && thread_group_empty(p: task)); |
1915 | rcu_read_unlock(); |
1916 | |
1917 | return exited; |
1918 | } |
1919 | EXPORT_SYMBOL(thread_group_exited); |
1920 | |
1921 | /* |
1922 | * This needs to be __function_aligned as GCC implicitly makes any |
1923 | * implementation of abort() cold and drops alignment specified by |
1924 | * -falign-functions=N. |
1925 | * |
1926 | * See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88345#c11 |
1927 | */ |
1928 | __weak __function_aligned void abort(void) |
1929 | { |
1930 | BUG(); |
1931 | |
1932 | /* if that doesn't kill us, halt */ |
1933 | panic(fmt: "Oops failed to kill thread" ); |
1934 | } |
1935 | EXPORT_SYMBOL(abort); |
1936 | |