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Merge branch 'locking/urgent' into locking/core, to pick up fixes before applying...
[mirror_ubuntu-bionic-kernel.git] / kernel / exit.c
CommitLineData
1da177e4
LT
1/*
2 * linux/kernel/exit.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
1da177e4
LT
7#include <linux/mm.h>
8#include <linux/slab.h>
9#include <linux/interrupt.h>
1da177e4 10#include <linux/module.h>
c59ede7b 11#include <linux/capability.h>
1da177e4
LT
12#include <linux/completion.h>
13#include <linux/personality.h>
14#include <linux/tty.h>
da9cbc87 15#include <linux/iocontext.h>
1da177e4
LT
16#include <linux/key.h>
17#include <linux/security.h>
18#include <linux/cpu.h>
19#include <linux/acct.h>
8f0ab514 20#include <linux/tsacct_kern.h>
1da177e4 21#include <linux/file.h>
9f3acc31 22#include <linux/fdtable.h>
80d26af8 23#include <linux/freezer.h>
1da177e4 24#include <linux/binfmts.h>
ab516013 25#include <linux/nsproxy.h>
84d73786 26#include <linux/pid_namespace.h>
1da177e4
LT
27#include <linux/ptrace.h>
28#include <linux/profile.h>
29#include <linux/mount.h>
30#include <linux/proc_fs.h>
49d769d5 31#include <linux/kthread.h>
1da177e4 32#include <linux/mempolicy.h>
c757249a 33#include <linux/taskstats_kern.h>
ca74e92b 34#include <linux/delayacct.h>
b4f48b63 35#include <linux/cgroup.h>
1da177e4 36#include <linux/syscalls.h>
7ed20e1a 37#include <linux/signal.h>
6a14c5c9 38#include <linux/posix-timers.h>
9f46080c 39#include <linux/cn_proc.h>
de5097c2 40#include <linux/mutex.h>
0771dfef 41#include <linux/futex.h>
b92ce558 42#include <linux/pipe_fs_i.h>
fa84cb93 43#include <linux/audit.h> /* for audit_free() */
83cc5ed3 44#include <linux/resource.h>
0d67a46d 45#include <linux/blkdev.h>
6eaeeaba 46#include <linux/task_io_accounting_ops.h>
30199f5a 47#include <linux/tracehook.h>
5ad4e53b 48#include <linux/fs_struct.h>
d84f4f99 49#include <linux/init_task.h>
cdd6c482 50#include <linux/perf_event.h>
ad8d75ff 51#include <trace/events/sched.h>
24f1e32c 52#include <linux/hw_breakpoint.h>
3d5992d2 53#include <linux/oom.h>
54848d73 54#include <linux/writeback.h>
40401530 55#include <linux/shm.h>
1da177e4
LT
56
57#include <asm/uaccess.h>
58#include <asm/unistd.h>
59#include <asm/pgtable.h>
60#include <asm/mmu_context.h>
61
a0be55de 62static void exit_mm(struct task_struct *tsk);
408b664a 63
d40e48e0 64static void __unhash_process(struct task_struct *p, bool group_dead)
1da177e4
LT
65{
66 nr_threads--;
50d75f8d 67 detach_pid(p, PIDTYPE_PID);
d40e48e0 68 if (group_dead) {
1da177e4
LT
69 detach_pid(p, PIDTYPE_PGID);
70 detach_pid(p, PIDTYPE_SID);
c97d9893 71
5e85d4ab 72 list_del_rcu(&p->tasks);
9cd80bbb 73 list_del_init(&p->sibling);
909ea964 74 __this_cpu_dec(process_counts);
1da177e4 75 }
47e65328 76 list_del_rcu(&p->thread_group);
0c740d0a 77 list_del_rcu(&p->thread_node);
1da177e4
LT
78}
79
6a14c5c9
ON
80/*
81 * This function expects the tasklist_lock write-locked.
82 */
83static void __exit_signal(struct task_struct *tsk)
84{
85 struct signal_struct *sig = tsk->signal;
d40e48e0 86 bool group_dead = thread_group_leader(tsk);
6a14c5c9 87 struct sighand_struct *sighand;
4ada856f 88 struct tty_struct *uninitialized_var(tty);
6fac4829 89 cputime_t utime, stime;
6a14c5c9 90
d11c563d 91 sighand = rcu_dereference_check(tsk->sighand,
db1466b3 92 lockdep_tasklist_lock_is_held());
6a14c5c9
ON
93 spin_lock(&sighand->siglock);
94
95 posix_cpu_timers_exit(tsk);
d40e48e0 96 if (group_dead) {
6a14c5c9 97 posix_cpu_timers_exit_group(tsk);
4ada856f
ON
98 tty = sig->tty;
99 sig->tty = NULL;
4a599942 100 } else {
e0a70217
ON
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
6a14c5c9
ON
109 /*
110 * If there is any task waiting for the group exit
111 * then notify it:
112 */
d344193a 113 if (sig->notify_count > 0 && !--sig->notify_count)
6a14c5c9 114 wake_up_process(sig->group_exit_task);
6db840fa 115
6a14c5c9
ON
116 if (tsk == sig->curr_target)
117 sig->curr_target = next_thread(tsk);
6a14c5c9
ON
118 }
119
90ed9cbe 120 /*
26e75b5c
ON
121 * Accumulate here the counters for all threads as they die. We could
122 * skip the group leader because it is the last user of signal_struct,
123 * but we want to avoid the race with thread_group_cputime() which can
124 * see the empty ->thread_head list.
90ed9cbe
RR
125 */
126 task_cputime(tsk, &utime, &stime);
e78c3496 127 write_seqlock(&sig->stats_lock);
90ed9cbe
RR
128 sig->utime += utime;
129 sig->stime += stime;
130 sig->gtime += task_gtime(tsk);
131 sig->min_flt += tsk->min_flt;
132 sig->maj_flt += tsk->maj_flt;
133 sig->nvcsw += tsk->nvcsw;
134 sig->nivcsw += tsk->nivcsw;
135 sig->inblock += task_io_get_inblock(tsk);
136 sig->oublock += task_io_get_oublock(tsk);
137 task_io_accounting_add(&sig->ioac, &tsk->ioac);
138 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
b3ac022c 139 sig->nr_threads--;
d40e48e0 140 __unhash_process(tsk, group_dead);
e78c3496 141 write_sequnlock(&sig->stats_lock);
5876700c 142
da7978b0
ON
143 /*
144 * Do this under ->siglock, we can race with another thread
145 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
146 */
147 flush_sigqueue(&tsk->pending);
a7e5328a 148 tsk->sighand = NULL;
6a14c5c9 149 spin_unlock(&sighand->siglock);
6a14c5c9 150
a7e5328a 151 __cleanup_sighand(sighand);
a0be55de 152 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
d40e48e0 153 if (group_dead) {
6a14c5c9 154 flush_sigqueue(&sig->shared_pending);
4ada856f 155 tty_kref_put(tty);
6a14c5c9
ON
156 }
157}
158
8c7904a0
EB
159static void delayed_put_task_struct(struct rcu_head *rhp)
160{
0a16b607
MD
161 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
162
4e231c79 163 perf_event_delayed_put(tsk);
0a16b607
MD
164 trace_sched_process_free(tsk);
165 put_task_struct(tsk);
8c7904a0
EB
166}
167
f470021a 168
a0be55de 169void release_task(struct task_struct *p)
1da177e4 170{
36c8b586 171 struct task_struct *leader;
1da177e4 172 int zap_leader;
1f09f974 173repeat:
c69e8d9c 174 /* don't need to get the RCU readlock here - the process is dead and
d11c563d
PM
175 * can't be modifying its own credentials. But shut RCU-lockdep up */
176 rcu_read_lock();
c69e8d9c 177 atomic_dec(&__task_cred(p)->user->processes);
d11c563d 178 rcu_read_unlock();
c69e8d9c 179
60347f67 180 proc_flush_task(p);
0203026b 181
1da177e4 182 write_lock_irq(&tasklist_lock);
a288eecc 183 ptrace_release_task(p);
1da177e4 184 __exit_signal(p);
35f5cad8 185
1da177e4
LT
186 /*
187 * If we are the last non-leader member of the thread
188 * group, and the leader is zombie, then notify the
189 * group leader's parent process. (if it wants notification.)
190 */
191 zap_leader = 0;
192 leader = p->group_leader;
a0be55de
IA
193 if (leader != p && thread_group_empty(leader)
194 && leader->exit_state == EXIT_ZOMBIE) {
1da177e4
LT
195 /*
196 * If we were the last child thread and the leader has
197 * exited already, and the leader's parent ignores SIGCHLD,
198 * then we are the one who should release the leader.
dae33574 199 */
86773473 200 zap_leader = do_notify_parent(leader, leader->exit_signal);
dae33574
RM
201 if (zap_leader)
202 leader->exit_state = EXIT_DEAD;
1da177e4
LT
203 }
204
1da177e4 205 write_unlock_irq(&tasklist_lock);
1da177e4 206 release_thread(p);
8c7904a0 207 call_rcu(&p->rcu, delayed_put_task_struct);
1da177e4
LT
208
209 p = leader;
210 if (unlikely(zap_leader))
211 goto repeat;
212}
213
1da177e4
LT
214/*
215 * Determine if a process group is "orphaned", according to the POSIX
216 * definition in 2.2.2.52. Orphaned process groups are not to be affected
217 * by terminal-generated stop signals. Newly orphaned process groups are
218 * to receive a SIGHUP and a SIGCONT.
219 *
220 * "I ask you, have you ever known what it is to be an orphan?"
221 */
a0be55de
IA
222static int will_become_orphaned_pgrp(struct pid *pgrp,
223 struct task_struct *ignored_task)
1da177e4
LT
224{
225 struct task_struct *p;
1da177e4 226
0475ac08 227 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
05e83df6
ON
228 if ((p == ignored_task) ||
229 (p->exit_state && thread_group_empty(p)) ||
230 is_global_init(p->real_parent))
1da177e4 231 continue;
05e83df6 232
0475ac08 233 if (task_pgrp(p->real_parent) != pgrp &&
05e83df6
ON
234 task_session(p->real_parent) == task_session(p))
235 return 0;
0475ac08 236 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
05e83df6
ON
237
238 return 1;
1da177e4
LT
239}
240
3e7cd6c4 241int is_current_pgrp_orphaned(void)
1da177e4
LT
242{
243 int retval;
244
245 read_lock(&tasklist_lock);
3e7cd6c4 246 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
1da177e4
LT
247 read_unlock(&tasklist_lock);
248
249 return retval;
250}
251
961c4675 252static bool has_stopped_jobs(struct pid *pgrp)
1da177e4 253{
1da177e4
LT
254 struct task_struct *p;
255
0475ac08 256 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
961c4675
ON
257 if (p->signal->flags & SIGNAL_STOP_STOPPED)
258 return true;
0475ac08 259 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
961c4675
ON
260
261 return false;
1da177e4
LT
262}
263
f49ee505
ON
264/*
265 * Check to see if any process groups have become orphaned as
266 * a result of our exiting, and if they have any stopped jobs,
267 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
268 */
269static void
270kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
271{
272 struct pid *pgrp = task_pgrp(tsk);
273 struct task_struct *ignored_task = tsk;
274
275 if (!parent)
a0be55de
IA
276 /* exit: our father is in a different pgrp than
277 * we are and we were the only connection outside.
278 */
f49ee505
ON
279 parent = tsk->real_parent;
280 else
281 /* reparent: our child is in a different pgrp than
282 * we are, and it was the only connection outside.
283 */
284 ignored_task = NULL;
285
286 if (task_pgrp(parent) != pgrp &&
287 task_session(parent) == task_session(tsk) &&
288 will_become_orphaned_pgrp(pgrp, ignored_task) &&
289 has_stopped_jobs(pgrp)) {
290 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
291 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
292 }
293}
294
f98bafa0 295#ifdef CONFIG_MEMCG
cf475ad2 296/*
733eda7a 297 * A task is exiting. If it owned this mm, find a new owner for the mm.
cf475ad2 298 */
cf475ad2
BS
299void mm_update_next_owner(struct mm_struct *mm)
300{
301 struct task_struct *c, *g, *p = current;
302
303retry:
733eda7a
KH
304 /*
305 * If the exiting or execing task is not the owner, it's
306 * someone else's problem.
307 */
308 if (mm->owner != p)
cf475ad2 309 return;
733eda7a
KH
310 /*
311 * The current owner is exiting/execing and there are no other
312 * candidates. Do not leave the mm pointing to a possibly
313 * freed task structure.
314 */
315 if (atomic_read(&mm->mm_users) <= 1) {
316 mm->owner = NULL;
317 return;
318 }
cf475ad2
BS
319
320 read_lock(&tasklist_lock);
321 /*
322 * Search in the children
323 */
324 list_for_each_entry(c, &p->children, sibling) {
325 if (c->mm == mm)
326 goto assign_new_owner;
327 }
328
329 /*
330 * Search in the siblings
331 */
dea33cfd 332 list_for_each_entry(c, &p->real_parent->children, sibling) {
cf475ad2
BS
333 if (c->mm == mm)
334 goto assign_new_owner;
335 }
336
337 /*
f87fb599 338 * Search through everything else, we should not get here often.
cf475ad2 339 */
39af1765
ON
340 for_each_process(g) {
341 if (g->flags & PF_KTHREAD)
342 continue;
343 for_each_thread(g, c) {
344 if (c->mm == mm)
345 goto assign_new_owner;
346 if (c->mm)
347 break;
348 }
f87fb599 349 }
cf475ad2 350 read_unlock(&tasklist_lock);
31a78f23
BS
351 /*
352 * We found no owner yet mm_users > 1: this implies that we are
353 * most likely racing with swapoff (try_to_unuse()) or /proc or
e5991371 354 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
31a78f23 355 */
31a78f23 356 mm->owner = NULL;
cf475ad2
BS
357 return;
358
359assign_new_owner:
360 BUG_ON(c == p);
361 get_task_struct(c);
362 /*
363 * The task_lock protects c->mm from changing.
364 * We always want mm->owner->mm == mm
365 */
366 task_lock(c);
e5991371
HD
367 /*
368 * Delay read_unlock() till we have the task_lock()
369 * to ensure that c does not slip away underneath us
370 */
371 read_unlock(&tasklist_lock);
cf475ad2
BS
372 if (c->mm != mm) {
373 task_unlock(c);
374 put_task_struct(c);
375 goto retry;
376 }
cf475ad2
BS
377 mm->owner = c;
378 task_unlock(c);
379 put_task_struct(c);
380}
f98bafa0 381#endif /* CONFIG_MEMCG */
cf475ad2 382
1da177e4
LT
383/*
384 * Turn us into a lazy TLB process if we
385 * aren't already..
386 */
a0be55de 387static void exit_mm(struct task_struct *tsk)
1da177e4
LT
388{
389 struct mm_struct *mm = tsk->mm;
b564daf8 390 struct core_state *core_state;
1da177e4 391
48d212a2 392 mm_release(tsk, mm);
1da177e4
LT
393 if (!mm)
394 return;
4fe7efdb 395 sync_mm_rss(mm);
1da177e4
LT
396 /*
397 * Serialize with any possible pending coredump.
999d9fc1 398 * We must hold mmap_sem around checking core_state
1da177e4 399 * and clearing tsk->mm. The core-inducing thread
999d9fc1 400 * will increment ->nr_threads for each thread in the
1da177e4
LT
401 * group with ->mm != NULL.
402 */
403 down_read(&mm->mmap_sem);
b564daf8
ON
404 core_state = mm->core_state;
405 if (core_state) {
406 struct core_thread self;
a0be55de 407
1da177e4 408 up_read(&mm->mmap_sem);
1da177e4 409
b564daf8
ON
410 self.task = tsk;
411 self.next = xchg(&core_state->dumper.next, &self);
412 /*
413 * Implies mb(), the result of xchg() must be visible
414 * to core_state->dumper.
415 */
416 if (atomic_dec_and_test(&core_state->nr_threads))
417 complete(&core_state->startup);
1da177e4 418
a94e2d40
ON
419 for (;;) {
420 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
421 if (!self.task) /* see coredump_finish() */
422 break;
80d26af8 423 freezable_schedule();
a94e2d40
ON
424 }
425 __set_task_state(tsk, TASK_RUNNING);
1da177e4
LT
426 down_read(&mm->mmap_sem);
427 }
428 atomic_inc(&mm->mm_count);
125e1874 429 BUG_ON(mm != tsk->active_mm);
1da177e4
LT
430 /* more a memory barrier than a real lock */
431 task_lock(tsk);
432 tsk->mm = NULL;
433 up_read(&mm->mmap_sem);
434 enter_lazy_tlb(mm, current);
435 task_unlock(tsk);
cf475ad2 436 mm_update_next_owner(mm);
1da177e4 437 mmput(mm);
c32b3cbe 438 if (test_thread_flag(TIF_MEMDIE))
16e95196 439 exit_oom_victim();
1da177e4
LT
440}
441
c9dc05bf
ON
442static struct task_struct *find_alive_thread(struct task_struct *p)
443{
444 struct task_struct *t;
445
446 for_each_thread(p, t) {
447 if (!(t->flags & PF_EXITING))
448 return t;
449 }
450 return NULL;
451}
452
1109909c
ON
453static struct task_struct *find_child_reaper(struct task_struct *father)
454 __releases(&tasklist_lock)
455 __acquires(&tasklist_lock)
456{
457 struct pid_namespace *pid_ns = task_active_pid_ns(father);
458 struct task_struct *reaper = pid_ns->child_reaper;
459
460 if (likely(reaper != father))
461 return reaper;
462
c9dc05bf
ON
463 reaper = find_alive_thread(father);
464 if (reaper) {
1109909c
ON
465 pid_ns->child_reaper = reaper;
466 return reaper;
467 }
468
469 write_unlock_irq(&tasklist_lock);
470 if (unlikely(pid_ns == &init_pid_ns)) {
471 panic("Attempted to kill init! exitcode=0x%08x\n",
472 father->signal->group_exit_code ?: father->exit_code);
473 }
474 zap_pid_ns_processes(pid_ns);
475 write_lock_irq(&tasklist_lock);
476
477 return father;
478}
479
1da177e4 480/*
ebec18a6
LP
481 * When we die, we re-parent all our children, and try to:
482 * 1. give them to another thread in our thread group, if such a member exists
483 * 2. give it to the first ancestor process which prctl'd itself as a
484 * child_subreaper for its children (like a service manager)
485 * 3. give it to the init process (PID 1) in our pid namespace
1da177e4 486 */
1109909c
ON
487static struct task_struct *find_new_reaper(struct task_struct *father,
488 struct task_struct *child_reaper)
1da177e4 489{
c9dc05bf 490 struct task_struct *thread, *reaper;
1da177e4 491
c9dc05bf
ON
492 thread = find_alive_thread(father);
493 if (thread)
950bbabb 494 return thread;
1da177e4 495
7d24e2df 496 if (father->signal->has_child_subreaper) {
ebec18a6 497 /*
175aed3f
ON
498 * Find the first ->is_child_subreaper ancestor in our pid_ns.
499 * We start from father to ensure we can not look into another
500 * namespace, this is safe because all its threads are dead.
ebec18a6 501 */
7d24e2df 502 for (reaper = father;
1109909c 503 !same_thread_group(reaper, child_reaper);
ebec18a6 504 reaper = reaper->real_parent) {
175aed3f
ON
505 /* call_usermodehelper() descendants need this check */
506 if (reaper == &init_task)
ebec18a6
LP
507 break;
508 if (!reaper->signal->is_child_subreaper)
509 continue;
c9dc05bf
ON
510 thread = find_alive_thread(reaper);
511 if (thread)
512 return thread;
ebec18a6 513 }
1da177e4 514 }
762a24be 515
1109909c 516 return child_reaper;
950bbabb
ON
517}
518
5dfc80be
ON
519/*
520* Any that need to be release_task'd are put on the @dead list.
521 */
9cd80bbb 522static void reparent_leader(struct task_struct *father, struct task_struct *p,
5dfc80be
ON
523 struct list_head *dead)
524{
2831096e 525 if (unlikely(p->exit_state == EXIT_DEAD))
5dfc80be
ON
526 return;
527
abd50b39 528 /* We don't want people slaying init. */
5dfc80be
ON
529 p->exit_signal = SIGCHLD;
530
531 /* If it has exited notify the new parent about this child's death. */
d21142ec 532 if (!p->ptrace &&
5dfc80be 533 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
86773473 534 if (do_notify_parent(p, p->exit_signal)) {
5dfc80be 535 p->exit_state = EXIT_DEAD;
dc2fd4b0 536 list_add(&p->ptrace_entry, dead);
5dfc80be
ON
537 }
538 }
539
540 kill_orphaned_pgrp(p, father);
541}
542
482a3767
ON
543/*
544 * This does two things:
545 *
546 * A. Make init inherit all the child processes
547 * B. Check to see if any process groups have become orphaned
548 * as a result of our exiting, and if they have any stopped
549 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
550 */
551static void forget_original_parent(struct task_struct *father,
552 struct list_head *dead)
1da177e4 553{
482a3767 554 struct task_struct *p, *t, *reaper;
762a24be 555
7c8bd232 556 if (unlikely(!list_empty(&father->ptraced)))
482a3767 557 exit_ptrace(father, dead);
f470021a 558
7c8bd232 559 /* Can drop and reacquire tasklist_lock */
1109909c 560 reaper = find_child_reaper(father);
ad9e206a 561 if (list_empty(&father->children))
482a3767 562 return;
1109909c
ON
563
564 reaper = find_new_reaper(father, reaper);
2831096e 565 list_for_each_entry(p, &father->children, sibling) {
57a05918 566 for_each_thread(p, t) {
9cd80bbb 567 t->real_parent = reaper;
57a05918
ON
568 BUG_ON((!t->ptrace) != (t->parent == father));
569 if (likely(!t->ptrace))
9cd80bbb 570 t->parent = t->real_parent;
9cd80bbb
ON
571 if (t->pdeath_signal)
572 group_send_sig_info(t->pdeath_signal,
573 SEND_SIG_NOINFO, t);
57a05918 574 }
2831096e
ON
575 /*
576 * If this is a threaded reparent there is no need to
577 * notify anyone anything has happened.
578 */
579 if (!same_thread_group(reaper, father))
482a3767 580 reparent_leader(father, p, dead);
1da177e4 581 }
2831096e 582 list_splice_tail_init(&father->children, &reaper->children);
1da177e4
LT
583}
584
585/*
586 * Send signals to all our closest relatives so that they know
587 * to properly mourn us..
588 */
821c7de7 589static void exit_notify(struct task_struct *tsk, int group_dead)
1da177e4 590{
53c8f9f1 591 bool autoreap;
482a3767
ON
592 struct task_struct *p, *n;
593 LIST_HEAD(dead);
1da177e4 594
762a24be 595 write_lock_irq(&tasklist_lock);
482a3767
ON
596 forget_original_parent(tsk, &dead);
597
821c7de7
ON
598 if (group_dead)
599 kill_orphaned_pgrp(tsk->group_leader, NULL);
1da177e4 600
45cdf5cc
ON
601 if (unlikely(tsk->ptrace)) {
602 int sig = thread_group_leader(tsk) &&
603 thread_group_empty(tsk) &&
604 !ptrace_reparented(tsk) ?
605 tsk->exit_signal : SIGCHLD;
606 autoreap = do_notify_parent(tsk, sig);
607 } else if (thread_group_leader(tsk)) {
608 autoreap = thread_group_empty(tsk) &&
609 do_notify_parent(tsk, tsk->exit_signal);
610 } else {
611 autoreap = true;
612 }
1da177e4 613
53c8f9f1 614 tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
6c66e7db
ON
615 if (tsk->exit_state == EXIT_DEAD)
616 list_add(&tsk->ptrace_entry, &dead);
1da177e4 617
9c339168
ON
618 /* mt-exec, de_thread() is waiting for group leader */
619 if (unlikely(tsk->signal->notify_count < 0))
6db840fa 620 wake_up_process(tsk->signal->group_exit_task);
1da177e4
LT
621 write_unlock_irq(&tasklist_lock);
622
482a3767
ON
623 list_for_each_entry_safe(p, n, &dead, ptrace_entry) {
624 list_del_init(&p->ptrace_entry);
625 release_task(p);
626 }
1da177e4
LT
627}
628
e18eecb8
JD
629#ifdef CONFIG_DEBUG_STACK_USAGE
630static void check_stack_usage(void)
631{
632 static DEFINE_SPINLOCK(low_water_lock);
633 static int lowest_to_date = THREAD_SIZE;
e18eecb8
JD
634 unsigned long free;
635
7c9f8861 636 free = stack_not_used(current);
e18eecb8
JD
637
638 if (free >= lowest_to_date)
639 return;
640
641 spin_lock(&low_water_lock);
642 if (free < lowest_to_date) {
a0be55de
IA
643 pr_warn("%s (%d) used greatest stack depth: %lu bytes left\n",
644 current->comm, task_pid_nr(current), free);
e18eecb8
JD
645 lowest_to_date = free;
646 }
647 spin_unlock(&low_water_lock);
648}
649#else
650static inline void check_stack_usage(void) {}
651#endif
652
9402c95f 653void do_exit(long code)
1da177e4
LT
654{
655 struct task_struct *tsk = current;
656 int group_dead;
3f95aa81 657 TASKS_RCU(int tasks_rcu_i);
1da177e4
LT
658
659 profile_task_exit(tsk);
660
73c10101 661 WARN_ON(blk_needs_flush_plug(tsk));
22e2c507 662
1da177e4
LT
663 if (unlikely(in_interrupt()))
664 panic("Aiee, killing interrupt handler!");
665 if (unlikely(!tsk->pid))
666 panic("Attempted to kill the idle task!");
1da177e4 667
33dd94ae
NE
668 /*
669 * If do_exit is called because this processes oopsed, it's possible
670 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
671 * continuing. Amongst other possible reasons, this is to prevent
672 * mm_release()->clear_child_tid() from writing to a user-controlled
673 * kernel address.
674 */
675 set_fs(USER_DS);
676
a288eecc 677 ptrace_event(PTRACE_EVENT_EXIT, code);
1da177e4 678
e0e81739
DH
679 validate_creds_for_do_exit(tsk);
680
df164db5
AN
681 /*
682 * We're taking recursive faults here in do_exit. Safest is to just
683 * leave this task alone and wait for reboot.
684 */
685 if (unlikely(tsk->flags & PF_EXITING)) {
a0be55de 686 pr_alert("Fixing recursive fault but reboot is needed!\n");
778e9a9c
AK
687 /*
688 * We can do this unlocked here. The futex code uses
689 * this flag just to verify whether the pi state
690 * cleanup has been done or not. In the worst case it
691 * loops once more. We pretend that the cleanup was
692 * done as there is no way to return. Either the
693 * OWNER_DIED bit is set by now or we push the blocked
694 * task into the wait for ever nirwana as well.
695 */
696 tsk->flags |= PF_EXITPIDONE;
df164db5
AN
697 set_current_state(TASK_UNINTERRUPTIBLE);
698 schedule();
699 }
700
d12619b5 701 exit_signals(tsk); /* sets PF_EXITING */
778e9a9c
AK
702 /*
703 * tsk->flags are checked in the futex code to protect against
ed3e694d 704 * an exiting task cleaning up the robust pi futexes.
778e9a9c 705 */
d2ee7198 706 smp_mb();
1d615482 707 raw_spin_unlock_wait(&tsk->pi_lock);
1da177e4 708
1da177e4 709 if (unlikely(in_atomic()))
a0be55de
IA
710 pr_info("note: %s[%d] exited with preempt_count %d\n",
711 current->comm, task_pid_nr(current),
712 preempt_count());
1da177e4 713
48d212a2
LT
714 /* sync mm's RSS info before statistics gathering */
715 if (tsk->mm)
716 sync_mm_rss(tsk->mm);
51229b49 717 acct_update_integrals(tsk);
1da177e4 718 group_dead = atomic_dec_and_test(&tsk->signal->live);
c3068951 719 if (group_dead) {
778e9a9c 720 hrtimer_cancel(&tsk->signal->real_timer);
25f407f0 721 exit_itimers(tsk->signal);
1f10206c
JP
722 if (tsk->mm)
723 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
c3068951 724 }
f6ec29a4 725 acct_collect(code, group_dead);
522ed776
MT
726 if (group_dead)
727 tty_audit_exit();
a4ff8dba 728 audit_free(tsk);
115085ea 729
48d212a2 730 tsk->exit_code = code;
115085ea 731 taskstats_exit(tsk, group_dead);
c757249a 732
1da177e4
LT
733 exit_mm(tsk);
734
0e464814 735 if (group_dead)
f6ec29a4 736 acct_process();
0a16b607
MD
737 trace_sched_process_exit(tsk);
738
1da177e4 739 exit_sem(tsk);
b34a6b1d 740 exit_shm(tsk);
1ec7f1dd
AV
741 exit_files(tsk);
742 exit_fs(tsk);
c39df5fa
ON
743 if (group_dead)
744 disassociate_ctty(1);
8aac6270 745 exit_task_namespaces(tsk);
ed3e694d 746 exit_task_work(tsk);
1da177e4 747 exit_thread();
0b3fcf17
SE
748
749 /*
750 * Flush inherited counters to the parent - before the parent
751 * gets woken up by child-exit notifications.
752 *
753 * because of cgroup mode, must be called before cgroup_exit()
754 */
755 perf_event_exit_task(tsk);
756
1ec41830 757 cgroup_exit(tsk);
1da177e4 758
24f1e32c
FW
759 /*
760 * FIXME: do that only when needed, using sched_exit tracepoint
761 */
7c8df286 762 flush_ptrace_hw_breakpoint(tsk);
33b2fb30 763
3f95aa81 764 TASKS_RCU(tasks_rcu_i = __srcu_read_lock(&tasks_rcu_exit_srcu));
821c7de7 765 exit_notify(tsk, group_dead);
ef982393 766 proc_exit_connector(tsk);
1da177e4 767#ifdef CONFIG_NUMA
c0ff7453 768 task_lock(tsk);
f0be3d32 769 mpol_put(tsk->mempolicy);
1da177e4 770 tsk->mempolicy = NULL;
c0ff7453 771 task_unlock(tsk);
1da177e4 772#endif
42b2dd0a 773#ifdef CONFIG_FUTEX
c87e2837
IM
774 if (unlikely(current->pi_state_cache))
775 kfree(current->pi_state_cache);
42b2dd0a 776#endif
de5097c2 777 /*
9a11b49a 778 * Make sure we are holding no locks:
de5097c2 779 */
1b1d2fb4 780 debug_check_no_locks_held();
778e9a9c
AK
781 /*
782 * We can do this unlocked here. The futex code uses this flag
783 * just to verify whether the pi state cleanup has been done
784 * or not. In the worst case it loops once more.
785 */
786 tsk->flags |= PF_EXITPIDONE;
1da177e4 787
afc847b7 788 if (tsk->io_context)
b69f2292 789 exit_io_context(tsk);
afc847b7 790
b92ce558 791 if (tsk->splice_pipe)
4b8a8f1e 792 free_pipe_info(tsk->splice_pipe);
b92ce558 793
5640f768
ED
794 if (tsk->task_frag.page)
795 put_page(tsk->task_frag.page);
796
e0e81739
DH
797 validate_creds_for_do_exit(tsk);
798
4bcb8232 799 check_stack_usage();
7407251a 800 preempt_disable();
54848d73
WF
801 if (tsk->nr_dirtied)
802 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
f41d911f 803 exit_rcu();
3f95aa81 804 TASKS_RCU(__srcu_read_unlock(&tasks_rcu_exit_srcu, tasks_rcu_i));
b5740f4b
YG
805
806 /*
807 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
808 * when the following two conditions become true.
809 * - There is race condition of mmap_sem (It is acquired by
810 * exit_mm()), and
811 * - SMI occurs before setting TASK_RUNINNG.
812 * (or hypervisor of virtual machine switches to other guest)
813 * As a result, we may become TASK_RUNNING after becoming TASK_DEAD
814 *
815 * To avoid it, we have to wait for releasing tsk->pi_lock which
816 * is held by try_to_wake_up()
817 */
818 smp_mb();
819 raw_spin_unlock_wait(&tsk->pi_lock);
820
55a101f8 821 /* causes final put_task_struct in finish_task_switch(). */
c394cc9f 822 tsk->state = TASK_DEAD;
a585042f 823 tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */
1da177e4
LT
824 schedule();
825 BUG();
826 /* Avoid "noreturn function does return". */
54306cf0
AC
827 for (;;)
828 cpu_relax(); /* For when BUG is null */
1da177e4 829}
012914da
RA
830EXPORT_SYMBOL_GPL(do_exit);
831
9402c95f 832void complete_and_exit(struct completion *comp, long code)
1da177e4
LT
833{
834 if (comp)
835 complete(comp);
55a101f8 836
1da177e4
LT
837 do_exit(code);
838}
1da177e4
LT
839EXPORT_SYMBOL(complete_and_exit);
840
754fe8d2 841SYSCALL_DEFINE1(exit, int, error_code)
1da177e4
LT
842{
843 do_exit((error_code&0xff)<<8);
844}
845
1da177e4
LT
846/*
847 * Take down every thread in the group. This is called by fatal signals
848 * as well as by sys_exit_group (below).
849 */
9402c95f 850void
1da177e4
LT
851do_group_exit(int exit_code)
852{
bfc4b089
ON
853 struct signal_struct *sig = current->signal;
854
1da177e4
LT
855 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
856
bfc4b089
ON
857 if (signal_group_exit(sig))
858 exit_code = sig->group_exit_code;
1da177e4 859 else if (!thread_group_empty(current)) {
1da177e4 860 struct sighand_struct *const sighand = current->sighand;
a0be55de 861
1da177e4 862 spin_lock_irq(&sighand->siglock);
ed5d2cac 863 if (signal_group_exit(sig))
1da177e4
LT
864 /* Another thread got here before we took the lock. */
865 exit_code = sig->group_exit_code;
866 else {
1da177e4 867 sig->group_exit_code = exit_code;
ed5d2cac 868 sig->flags = SIGNAL_GROUP_EXIT;
1da177e4
LT
869 zap_other_threads(current);
870 }
871 spin_unlock_irq(&sighand->siglock);
1da177e4
LT
872 }
873
874 do_exit(exit_code);
875 /* NOTREACHED */
876}
877
878/*
879 * this kills every thread in the thread group. Note that any externally
880 * wait4()-ing process will get the correct exit code - even if this
881 * thread is not the thread group leader.
882 */
754fe8d2 883SYSCALL_DEFINE1(exit_group, int, error_code)
1da177e4
LT
884{
885 do_group_exit((error_code & 0xff) << 8);
2ed7c03e
HC
886 /* NOTREACHED */
887 return 0;
1da177e4
LT
888}
889
9e8ae01d
ON
890struct wait_opts {
891 enum pid_type wo_type;
9e8ae01d 892 int wo_flags;
e1eb1ebc 893 struct pid *wo_pid;
9e8ae01d
ON
894
895 struct siginfo __user *wo_info;
896 int __user *wo_stat;
897 struct rusage __user *wo_rusage;
898
0b7570e7 899 wait_queue_t child_wait;
9e8ae01d
ON
900 int notask_error;
901};
902
989264f4
ON
903static inline
904struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
161550d7 905{
989264f4
ON
906 if (type != PIDTYPE_PID)
907 task = task->group_leader;
908 return task->pids[type].pid;
161550d7
EB
909}
910
989264f4 911static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
1da177e4 912{
5c01ba49
ON
913 return wo->wo_type == PIDTYPE_MAX ||
914 task_pid_type(p, wo->wo_type) == wo->wo_pid;
915}
1da177e4 916
5c01ba49
ON
917static int eligible_child(struct wait_opts *wo, struct task_struct *p)
918{
919 if (!eligible_pid(wo, p))
920 return 0;
1da177e4
LT
921 /* Wait for all children (clone and not) if __WALL is set;
922 * otherwise, wait for clone children *only* if __WCLONE is
923 * set; otherwise, wait for non-clone children *only*. (Note:
924 * A "clone" child here is one that reports to its parent
925 * using a signal other than SIGCHLD.) */
9e8ae01d
ON
926 if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
927 && !(wo->wo_flags & __WALL))
1da177e4 928 return 0;
1da177e4 929
14dd0b81 930 return 1;
1da177e4
LT
931}
932
9e8ae01d
ON
933static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
934 pid_t pid, uid_t uid, int why, int status)
1da177e4 935{
9e8ae01d
ON
936 struct siginfo __user *infop;
937 int retval = wo->wo_rusage
938 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
36c8b586 939
1da177e4 940 put_task_struct(p);
9e8ae01d 941 infop = wo->wo_info;
b6fe2d11
VM
942 if (infop) {
943 if (!retval)
944 retval = put_user(SIGCHLD, &infop->si_signo);
945 if (!retval)
946 retval = put_user(0, &infop->si_errno);
947 if (!retval)
948 retval = put_user((short)why, &infop->si_code);
949 if (!retval)
950 retval = put_user(pid, &infop->si_pid);
951 if (!retval)
952 retval = put_user(uid, &infop->si_uid);
953 if (!retval)
954 retval = put_user(status, &infop->si_status);
955 }
1da177e4
LT
956 if (!retval)
957 retval = pid;
958 return retval;
959}
960
961/*
962 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
963 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
964 * the lock and this task is uninteresting. If we return nonzero, we have
965 * released the lock and the system call should return.
966 */
9e8ae01d 967static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
1da177e4 968{
f6507f83 969 int state, retval, status;
6c5f3e7b 970 pid_t pid = task_pid_vnr(p);
43e13cc1 971 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
9e8ae01d 972 struct siginfo __user *infop;
1da177e4 973
9e8ae01d 974 if (!likely(wo->wo_flags & WEXITED))
98abed02
RM
975 return 0;
976
9e8ae01d 977 if (unlikely(wo->wo_flags & WNOWAIT)) {
1da177e4 978 int exit_code = p->exit_code;
f3abd4f9 979 int why;
1da177e4 980
1da177e4
LT
981 get_task_struct(p);
982 read_unlock(&tasklist_lock);
1029a2b5
PZ
983 sched_annotate_sleep();
984
1da177e4
LT
985 if ((exit_code & 0x7f) == 0) {
986 why = CLD_EXITED;
987 status = exit_code >> 8;
988 } else {
989 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
990 status = exit_code & 0x7f;
991 }
9e8ae01d 992 return wait_noreap_copyout(wo, p, pid, uid, why, status);
1da177e4 993 }
1da177e4 994 /*
abd50b39 995 * Move the task's state to DEAD/TRACE, only one thread can do this.
1da177e4 996 */
f6507f83
ON
997 state = (ptrace_reparented(p) && thread_group_leader(p)) ?
998 EXIT_TRACE : EXIT_DEAD;
abd50b39 999 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
1da177e4 1000 return 0;
986094df
ON
1001 /*
1002 * We own this thread, nobody else can reap it.
1003 */
1004 read_unlock(&tasklist_lock);
1005 sched_annotate_sleep();
f6507f83 1006
befca967 1007 /*
f6507f83 1008 * Check thread_group_leader() to exclude the traced sub-threads.
befca967 1009 */
f6507f83 1010 if (state == EXIT_DEAD && thread_group_leader(p)) {
f953ccd0
ON
1011 struct signal_struct *sig = p->signal;
1012 struct signal_struct *psig = current->signal;
1f10206c 1013 unsigned long maxrss;
0cf55e1e 1014 cputime_t tgutime, tgstime;
3795e161 1015
1da177e4
LT
1016 /*
1017 * The resource counters for the group leader are in its
1018 * own task_struct. Those for dead threads in the group
1019 * are in its signal_struct, as are those for the child
1020 * processes it has previously reaped. All these
1021 * accumulate in the parent's signal_struct c* fields.
1022 *
1023 * We don't bother to take a lock here to protect these
f953ccd0
ON
1024 * p->signal fields because the whole thread group is dead
1025 * and nobody can change them.
1026 *
1027 * psig->stats_lock also protects us from our sub-theads
1028 * which can reap other children at the same time. Until
1029 * we change k_getrusage()-like users to rely on this lock
1030 * we have to take ->siglock as well.
0cf55e1e 1031 *
a0be55de
IA
1032 * We use thread_group_cputime_adjusted() to get times for
1033 * the thread group, which consolidates times for all threads
1034 * in the group including the group leader.
1da177e4 1035 */
e80d0a1a 1036 thread_group_cputime_adjusted(p, &tgutime, &tgstime);
f953ccd0 1037 spin_lock_irq(&current->sighand->siglock);
e78c3496 1038 write_seqlock(&psig->stats_lock);
64861634
MS
1039 psig->cutime += tgutime + sig->cutime;
1040 psig->cstime += tgstime + sig->cstime;
6fac4829 1041 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
3795e161
JJ
1042 psig->cmin_flt +=
1043 p->min_flt + sig->min_flt + sig->cmin_flt;
1044 psig->cmaj_flt +=
1045 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1046 psig->cnvcsw +=
1047 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1048 psig->cnivcsw +=
1049 p->nivcsw + sig->nivcsw + sig->cnivcsw;
6eaeeaba
ED
1050 psig->cinblock +=
1051 task_io_get_inblock(p) +
1052 sig->inblock + sig->cinblock;
1053 psig->coublock +=
1054 task_io_get_oublock(p) +
1055 sig->oublock + sig->coublock;
1f10206c
JP
1056 maxrss = max(sig->maxrss, sig->cmaxrss);
1057 if (psig->cmaxrss < maxrss)
1058 psig->cmaxrss = maxrss;
5995477a
AR
1059 task_io_accounting_add(&psig->ioac, &p->ioac);
1060 task_io_accounting_add(&psig->ioac, &sig->ioac);
e78c3496 1061 write_sequnlock(&psig->stats_lock);
f953ccd0 1062 spin_unlock_irq(&current->sighand->siglock);
1da177e4
LT
1063 }
1064
9e8ae01d
ON
1065 retval = wo->wo_rusage
1066 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1da177e4
LT
1067 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1068 ? p->signal->group_exit_code : p->exit_code;
9e8ae01d
ON
1069 if (!retval && wo->wo_stat)
1070 retval = put_user(status, wo->wo_stat);
1071
1072 infop = wo->wo_info;
1da177e4
LT
1073 if (!retval && infop)
1074 retval = put_user(SIGCHLD, &infop->si_signo);
1075 if (!retval && infop)
1076 retval = put_user(0, &infop->si_errno);
1077 if (!retval && infop) {
1078 int why;
1079
1080 if ((status & 0x7f) == 0) {
1081 why = CLD_EXITED;
1082 status >>= 8;
1083 } else {
1084 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1085 status &= 0x7f;
1086 }
1087 retval = put_user((short)why, &infop->si_code);
1088 if (!retval)
1089 retval = put_user(status, &infop->si_status);
1090 }
1091 if (!retval && infop)
3a515e4a 1092 retval = put_user(pid, &infop->si_pid);
1da177e4 1093 if (!retval && infop)
c69e8d9c 1094 retval = put_user(uid, &infop->si_uid);
2f4e6e2a 1095 if (!retval)
3a515e4a 1096 retval = pid;
2f4e6e2a 1097
b4360690 1098 if (state == EXIT_TRACE) {
1da177e4 1099 write_lock_irq(&tasklist_lock);
2f4e6e2a
ON
1100 /* We dropped tasklist, ptracer could die and untrace */
1101 ptrace_unlink(p);
b4360690
ON
1102
1103 /* If parent wants a zombie, don't release it now */
1104 state = EXIT_ZOMBIE;
1105 if (do_notify_parent(p, p->exit_signal))
1106 state = EXIT_DEAD;
abd50b39 1107 p->exit_state = state;
1da177e4
LT
1108 write_unlock_irq(&tasklist_lock);
1109 }
abd50b39 1110 if (state == EXIT_DEAD)
1da177e4 1111 release_task(p);
2f4e6e2a 1112
1da177e4
LT
1113 return retval;
1114}
1115
90bc8d8b
ON
1116static int *task_stopped_code(struct task_struct *p, bool ptrace)
1117{
1118 if (ptrace) {
544b2c91
TH
1119 if (task_is_stopped_or_traced(p) &&
1120 !(p->jobctl & JOBCTL_LISTENING))
90bc8d8b
ON
1121 return &p->exit_code;
1122 } else {
1123 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1124 return &p->signal->group_exit_code;
1125 }
1126 return NULL;
1127}
1128
19e27463
TH
1129/**
1130 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1131 * @wo: wait options
1132 * @ptrace: is the wait for ptrace
1133 * @p: task to wait for
1134 *
1135 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1136 *
1137 * CONTEXT:
1138 * read_lock(&tasklist_lock), which is released if return value is
1139 * non-zero. Also, grabs and releases @p->sighand->siglock.
1140 *
1141 * RETURNS:
1142 * 0 if wait condition didn't exist and search for other wait conditions
1143 * should continue. Non-zero return, -errno on failure and @p's pid on
1144 * success, implies that tasklist_lock is released and wait condition
1145 * search should terminate.
1da177e4 1146 */
9e8ae01d
ON
1147static int wait_task_stopped(struct wait_opts *wo,
1148 int ptrace, struct task_struct *p)
1da177e4 1149{
9e8ae01d 1150 struct siginfo __user *infop;
90bc8d8b 1151 int retval, exit_code, *p_code, why;
ee7c82da 1152 uid_t uid = 0; /* unneeded, required by compiler */
c8950783 1153 pid_t pid;
1da177e4 1154
47918025
ON
1155 /*
1156 * Traditionally we see ptrace'd stopped tasks regardless of options.
1157 */
9e8ae01d 1158 if (!ptrace && !(wo->wo_flags & WUNTRACED))
98abed02
RM
1159 return 0;
1160
19e27463
TH
1161 if (!task_stopped_code(p, ptrace))
1162 return 0;
1163
ee7c82da
ON
1164 exit_code = 0;
1165 spin_lock_irq(&p->sighand->siglock);
1166
90bc8d8b
ON
1167 p_code = task_stopped_code(p, ptrace);
1168 if (unlikely(!p_code))
ee7c82da
ON
1169 goto unlock_sig;
1170
90bc8d8b 1171 exit_code = *p_code;
ee7c82da
ON
1172 if (!exit_code)
1173 goto unlock_sig;
1174
9e8ae01d 1175 if (!unlikely(wo->wo_flags & WNOWAIT))
90bc8d8b 1176 *p_code = 0;
ee7c82da 1177
8ca937a6 1178 uid = from_kuid_munged(current_user_ns(), task_uid(p));
ee7c82da
ON
1179unlock_sig:
1180 spin_unlock_irq(&p->sighand->siglock);
1181 if (!exit_code)
1da177e4
LT
1182 return 0;
1183
1184 /*
1185 * Now we are pretty sure this task is interesting.
1186 * Make sure it doesn't get reaped out from under us while we
1187 * give up the lock and then examine it below. We don't want to
1188 * keep holding onto the tasklist_lock while we call getrusage and
1189 * possibly take page faults for user memory.
1190 */
1191 get_task_struct(p);
6c5f3e7b 1192 pid = task_pid_vnr(p);
f470021a 1193 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1da177e4 1194 read_unlock(&tasklist_lock);
1029a2b5 1195 sched_annotate_sleep();
1da177e4 1196
9e8ae01d
ON
1197 if (unlikely(wo->wo_flags & WNOWAIT))
1198 return wait_noreap_copyout(wo, p, pid, uid, why, exit_code);
1199
1200 retval = wo->wo_rusage
1201 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1202 if (!retval && wo->wo_stat)
1203 retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
1da177e4 1204
9e8ae01d 1205 infop = wo->wo_info;
1da177e4
LT
1206 if (!retval && infop)
1207 retval = put_user(SIGCHLD, &infop->si_signo);
1208 if (!retval && infop)
1209 retval = put_user(0, &infop->si_errno);
1210 if (!retval && infop)
6efcae46 1211 retval = put_user((short)why, &infop->si_code);
1da177e4
LT
1212 if (!retval && infop)
1213 retval = put_user(exit_code, &infop->si_status);
1214 if (!retval && infop)
c8950783 1215 retval = put_user(pid, &infop->si_pid);
1da177e4 1216 if (!retval && infop)
ee7c82da 1217 retval = put_user(uid, &infop->si_uid);
1da177e4 1218 if (!retval)
c8950783 1219 retval = pid;
1da177e4
LT
1220 put_task_struct(p);
1221
1222 BUG_ON(!retval);
1223 return retval;
1224}
1225
1226/*
1227 * Handle do_wait work for one task in a live, non-stopped state.
1228 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1229 * the lock and this task is uninteresting. If we return nonzero, we have
1230 * released the lock and the system call should return.
1231 */
9e8ae01d 1232static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1da177e4
LT
1233{
1234 int retval;
1235 pid_t pid;
1236 uid_t uid;
1237
9e8ae01d 1238 if (!unlikely(wo->wo_flags & WCONTINUED))
98abed02
RM
1239 return 0;
1240
1da177e4
LT
1241 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1242 return 0;
1243
1244 spin_lock_irq(&p->sighand->siglock);
1245 /* Re-check with the lock held. */
1246 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1247 spin_unlock_irq(&p->sighand->siglock);
1248 return 0;
1249 }
9e8ae01d 1250 if (!unlikely(wo->wo_flags & WNOWAIT))
1da177e4 1251 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
8ca937a6 1252 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1da177e4
LT
1253 spin_unlock_irq(&p->sighand->siglock);
1254
6c5f3e7b 1255 pid = task_pid_vnr(p);
1da177e4
LT
1256 get_task_struct(p);
1257 read_unlock(&tasklist_lock);
1029a2b5 1258 sched_annotate_sleep();
1da177e4 1259
9e8ae01d
ON
1260 if (!wo->wo_info) {
1261 retval = wo->wo_rusage
1262 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1da177e4 1263 put_task_struct(p);
9e8ae01d
ON
1264 if (!retval && wo->wo_stat)
1265 retval = put_user(0xffff, wo->wo_stat);
1da177e4 1266 if (!retval)
3a515e4a 1267 retval = pid;
1da177e4 1268 } else {
9e8ae01d
ON
1269 retval = wait_noreap_copyout(wo, p, pid, uid,
1270 CLD_CONTINUED, SIGCONT);
1da177e4
LT
1271 BUG_ON(retval == 0);
1272 }
1273
1274 return retval;
1275}
1276
98abed02
RM
1277/*
1278 * Consider @p for a wait by @parent.
1279 *
9e8ae01d 1280 * -ECHILD should be in ->notask_error before the first call.
98abed02
RM
1281 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1282 * Returns zero if the search for a child should continue;
9e8ae01d 1283 * then ->notask_error is 0 if @p is an eligible child,
14dd0b81 1284 * or another error from security_task_wait(), or still -ECHILD.
98abed02 1285 */
b6e763f0
ON
1286static int wait_consider_task(struct wait_opts *wo, int ptrace,
1287 struct task_struct *p)
98abed02 1288{
3245d6ac
ON
1289 /*
1290 * We can race with wait_task_zombie() from another thread.
1291 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
1292 * can't confuse the checks below.
1293 */
1294 int exit_state = ACCESS_ONCE(p->exit_state);
b3ab0316
ON
1295 int ret;
1296
3245d6ac 1297 if (unlikely(exit_state == EXIT_DEAD))
b3ab0316
ON
1298 return 0;
1299
1300 ret = eligible_child(wo, p);
14dd0b81 1301 if (!ret)
98abed02
RM
1302 return ret;
1303
a2322e1d 1304 ret = security_task_wait(p);
14dd0b81
RM
1305 if (unlikely(ret < 0)) {
1306 /*
1307 * If we have not yet seen any eligible child,
1308 * then let this error code replace -ECHILD.
1309 * A permission error will give the user a clue
1310 * to look for security policy problems, rather
1311 * than for mysterious wait bugs.
1312 */
9e8ae01d
ON
1313 if (wo->notask_error)
1314 wo->notask_error = ret;
78a3d9d5 1315 return 0;
14dd0b81
RM
1316 }
1317
3245d6ac 1318 if (unlikely(exit_state == EXIT_TRACE)) {
50b8d257 1319 /*
abd50b39
ON
1320 * ptrace == 0 means we are the natural parent. In this case
1321 * we should clear notask_error, debugger will notify us.
50b8d257 1322 */
abd50b39 1323 if (likely(!ptrace))
50b8d257 1324 wo->notask_error = 0;
823b018e 1325 return 0;
50b8d257 1326 }
823b018e 1327
377d75da
ON
1328 if (likely(!ptrace) && unlikely(p->ptrace)) {
1329 /*
1330 * If it is traced by its real parent's group, just pretend
1331 * the caller is ptrace_do_wait() and reap this child if it
1332 * is zombie.
1333 *
1334 * This also hides group stop state from real parent; otherwise
1335 * a single stop can be reported twice as group and ptrace stop.
1336 * If a ptracer wants to distinguish these two events for its
1337 * own children it should create a separate process which takes
1338 * the role of real parent.
1339 */
1340 if (!ptrace_reparented(p))
1341 ptrace = 1;
1342 }
1343
45cb24a1 1344 /* slay zombie? */
3245d6ac 1345 if (exit_state == EXIT_ZOMBIE) {
9b84cca2 1346 /* we don't reap group leaders with subthreads */
7c733eb3
ON
1347 if (!delay_group_leader(p)) {
1348 /*
1349 * A zombie ptracee is only visible to its ptracer.
1350 * Notification and reaping will be cascaded to the
1351 * real parent when the ptracer detaches.
1352 */
1353 if (unlikely(ptrace) || likely(!p->ptrace))
1354 return wait_task_zombie(wo, p);
1355 }
98abed02 1356
f470021a 1357 /*
9b84cca2
TH
1358 * Allow access to stopped/continued state via zombie by
1359 * falling through. Clearing of notask_error is complex.
1360 *
1361 * When !@ptrace:
1362 *
1363 * If WEXITED is set, notask_error should naturally be
1364 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1365 * so, if there are live subthreads, there are events to
1366 * wait for. If all subthreads are dead, it's still safe
1367 * to clear - this function will be called again in finite
1368 * amount time once all the subthreads are released and
1369 * will then return without clearing.
1370 *
1371 * When @ptrace:
1372 *
1373 * Stopped state is per-task and thus can't change once the
1374 * target task dies. Only continued and exited can happen.
1375 * Clear notask_error if WCONTINUED | WEXITED.
1376 */
1377 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1378 wo->notask_error = 0;
1379 } else {
1380 /*
1381 * @p is alive and it's gonna stop, continue or exit, so
1382 * there always is something to wait for.
f470021a 1383 */
9e8ae01d 1384 wo->notask_error = 0;
f470021a
RM
1385 }
1386
98abed02 1387 /*
45cb24a1
TH
1388 * Wait for stopped. Depending on @ptrace, different stopped state
1389 * is used and the two don't interact with each other.
98abed02 1390 */
19e27463
TH
1391 ret = wait_task_stopped(wo, ptrace, p);
1392 if (ret)
1393 return ret;
98abed02
RM
1394
1395 /*
45cb24a1
TH
1396 * Wait for continued. There's only one continued state and the
1397 * ptracer can consume it which can confuse the real parent. Don't
1398 * use WCONTINUED from ptracer. You don't need or want it.
98abed02 1399 */
9e8ae01d 1400 return wait_task_continued(wo, p);
98abed02
RM
1401}
1402
1403/*
1404 * Do the work of do_wait() for one thread in the group, @tsk.
1405 *
9e8ae01d 1406 * -ECHILD should be in ->notask_error before the first call.
98abed02
RM
1407 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1408 * Returns zero if the search for a child should continue; then
9e8ae01d 1409 * ->notask_error is 0 if there were any eligible children,
14dd0b81 1410 * or another error from security_task_wait(), or still -ECHILD.
98abed02 1411 */
9e8ae01d 1412static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
98abed02
RM
1413{
1414 struct task_struct *p;
1415
1416 list_for_each_entry(p, &tsk->children, sibling) {
9cd80bbb 1417 int ret = wait_consider_task(wo, 0, p);
a0be55de 1418
9cd80bbb
ON
1419 if (ret)
1420 return ret;
98abed02
RM
1421 }
1422
1423 return 0;
1424}
1425
9e8ae01d 1426static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
98abed02
RM
1427{
1428 struct task_struct *p;
1429
f470021a 1430 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
b6e763f0 1431 int ret = wait_consider_task(wo, 1, p);
a0be55de 1432
f470021a 1433 if (ret)
98abed02 1434 return ret;
98abed02
RM
1435 }
1436
1437 return 0;
1438}
1439
0b7570e7
ON
1440static int child_wait_callback(wait_queue_t *wait, unsigned mode,
1441 int sync, void *key)
1442{
1443 struct wait_opts *wo = container_of(wait, struct wait_opts,
1444 child_wait);
1445 struct task_struct *p = key;
1446
5c01ba49 1447 if (!eligible_pid(wo, p))
0b7570e7
ON
1448 return 0;
1449
b4fe5182
ON
1450 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1451 return 0;
1452
0b7570e7
ON
1453 return default_wake_function(wait, mode, sync, key);
1454}
1455
a7f0765e
ON
1456void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1457{
0b7570e7
ON
1458 __wake_up_sync_key(&parent->signal->wait_chldexit,
1459 TASK_INTERRUPTIBLE, 1, p);
a7f0765e
ON
1460}
1461
9e8ae01d 1462static long do_wait(struct wait_opts *wo)
1da177e4 1463{
1da177e4 1464 struct task_struct *tsk;
98abed02 1465 int retval;
1da177e4 1466
9e8ae01d 1467 trace_sched_process_wait(wo->wo_pid);
0a16b607 1468
0b7570e7
ON
1469 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1470 wo->child_wait.private = current;
1471 add_wait_queue(&current->signal->wait_chldexit, &wo->child_wait);
1da177e4 1472repeat:
98abed02 1473 /*
3da56d16 1474 * If there is nothing that can match our criteria, just get out.
9e8ae01d
ON
1475 * We will clear ->notask_error to zero if we see any child that
1476 * might later match our criteria, even if we are not able to reap
1477 * it yet.
98abed02 1478 */
64a16caf 1479 wo->notask_error = -ECHILD;
9e8ae01d
ON
1480 if ((wo->wo_type < PIDTYPE_MAX) &&
1481 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
64a16caf 1482 goto notask;
161550d7 1483
f95d39d1 1484 set_current_state(TASK_INTERRUPTIBLE);
1da177e4
LT
1485 read_lock(&tasklist_lock);
1486 tsk = current;
1487 do {
64a16caf
ON
1488 retval = do_wait_thread(wo, tsk);
1489 if (retval)
1490 goto end;
9e8ae01d 1491
64a16caf
ON
1492 retval = ptrace_do_wait(wo, tsk);
1493 if (retval)
98abed02 1494 goto end;
98abed02 1495
9e8ae01d 1496 if (wo->wo_flags & __WNOTHREAD)
1da177e4 1497 break;
a3f6dfb7 1498 } while_each_thread(current, tsk);
1da177e4 1499 read_unlock(&tasklist_lock);
f2cc3eb1 1500
64a16caf 1501notask:
9e8ae01d
ON
1502 retval = wo->notask_error;
1503 if (!retval && !(wo->wo_flags & WNOHANG)) {
1da177e4 1504 retval = -ERESTARTSYS;
98abed02
RM
1505 if (!signal_pending(current)) {
1506 schedule();
1507 goto repeat;
1508 }
1da177e4 1509 }
1da177e4 1510end:
f95d39d1 1511 __set_current_state(TASK_RUNNING);
0b7570e7 1512 remove_wait_queue(&current->signal->wait_chldexit, &wo->child_wait);
1da177e4
LT
1513 return retval;
1514}
1515
17da2bd9
HC
1516SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1517 infop, int, options, struct rusage __user *, ru)
1da177e4 1518{
9e8ae01d 1519 struct wait_opts wo;
161550d7
EB
1520 struct pid *pid = NULL;
1521 enum pid_type type;
1da177e4
LT
1522 long ret;
1523
1524 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1525 return -EINVAL;
1526 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1527 return -EINVAL;
1528
1529 switch (which) {
1530 case P_ALL:
161550d7 1531 type = PIDTYPE_MAX;
1da177e4
LT
1532 break;
1533 case P_PID:
161550d7
EB
1534 type = PIDTYPE_PID;
1535 if (upid <= 0)
1da177e4
LT
1536 return -EINVAL;
1537 break;
1538 case P_PGID:
161550d7
EB
1539 type = PIDTYPE_PGID;
1540 if (upid <= 0)
1da177e4 1541 return -EINVAL;
1da177e4
LT
1542 break;
1543 default:
1544 return -EINVAL;
1545 }
1546
161550d7
EB
1547 if (type < PIDTYPE_MAX)
1548 pid = find_get_pid(upid);
9e8ae01d
ON
1549
1550 wo.wo_type = type;
1551 wo.wo_pid = pid;
1552 wo.wo_flags = options;
1553 wo.wo_info = infop;
1554 wo.wo_stat = NULL;
1555 wo.wo_rusage = ru;
1556 ret = do_wait(&wo);
dfe16dfa
VM
1557
1558 if (ret > 0) {
1559 ret = 0;
1560 } else if (infop) {
1561 /*
1562 * For a WNOHANG return, clear out all the fields
1563 * we would set so the user can easily tell the
1564 * difference.
1565 */
1566 if (!ret)
1567 ret = put_user(0, &infop->si_signo);
1568 if (!ret)
1569 ret = put_user(0, &infop->si_errno);
1570 if (!ret)
1571 ret = put_user(0, &infop->si_code);
1572 if (!ret)
1573 ret = put_user(0, &infop->si_pid);
1574 if (!ret)
1575 ret = put_user(0, &infop->si_uid);
1576 if (!ret)
1577 ret = put_user(0, &infop->si_status);
1578 }
1579
161550d7 1580 put_pid(pid);
1da177e4
LT
1581 return ret;
1582}
1583
754fe8d2
HC
1584SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1585 int, options, struct rusage __user *, ru)
1da177e4 1586{
9e8ae01d 1587 struct wait_opts wo;
161550d7
EB
1588 struct pid *pid = NULL;
1589 enum pid_type type;
1da177e4
LT
1590 long ret;
1591
1592 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1593 __WNOTHREAD|__WCLONE|__WALL))
1594 return -EINVAL;
161550d7
EB
1595
1596 if (upid == -1)
1597 type = PIDTYPE_MAX;
1598 else if (upid < 0) {
1599 type = PIDTYPE_PGID;
1600 pid = find_get_pid(-upid);
1601 } else if (upid == 0) {
1602 type = PIDTYPE_PGID;
2ae448ef 1603 pid = get_task_pid(current, PIDTYPE_PGID);
161550d7
EB
1604 } else /* upid > 0 */ {
1605 type = PIDTYPE_PID;
1606 pid = find_get_pid(upid);
1607 }
1608
9e8ae01d
ON
1609 wo.wo_type = type;
1610 wo.wo_pid = pid;
1611 wo.wo_flags = options | WEXITED;
1612 wo.wo_info = NULL;
1613 wo.wo_stat = stat_addr;
1614 wo.wo_rusage = ru;
1615 ret = do_wait(&wo);
161550d7 1616 put_pid(pid);
1da177e4 1617
1da177e4
LT
1618 return ret;
1619}
1620
1621#ifdef __ARCH_WANT_SYS_WAITPID
1622
1623/*
1624 * sys_waitpid() remains for compatibility. waitpid() should be
1625 * implemented by calling sys_wait4() from libc.a.
1626 */
17da2bd9 1627SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1da177e4
LT
1628{
1629 return sys_wait4(pid, stat_addr, options, NULL);
1630}
1631
1632#endif