exit.c 41.8 KB
Newer Older
L
Linus Torvalds 已提交
1 2 3 4 5 6 7 8 9 10
/*
 *  linux/kernel/exit.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/module.h>
11
#include <linux/capability.h>
L
Linus Torvalds 已提交
12 13 14
#include <linux/completion.h>
#include <linux/personality.h>
#include <linux/tty.h>
15
#include <linux/mnt_namespace.h>
L
Linus Torvalds 已提交
16 17 18 19
#include <linux/key.h>
#include <linux/security.h>
#include <linux/cpu.h>
#include <linux/acct.h>
20
#include <linux/tsacct_kern.h>
L
Linus Torvalds 已提交
21 22
#include <linux/file.h>
#include <linux/binfmts.h>
S
Serge E. Hallyn 已提交
23
#include <linux/nsproxy.h>
24
#include <linux/pid_namespace.h>
L
Linus Torvalds 已提交
25 26 27 28
#include <linux/ptrace.h>
#include <linux/profile.h>
#include <linux/mount.h>
#include <linux/proc_fs.h>
29
#include <linux/kthread.h>
L
Linus Torvalds 已提交
30
#include <linux/mempolicy.h>
31
#include <linux/taskstats_kern.h>
32
#include <linux/delayacct.h>
33
#include <linux/freezer.h>
34
#include <linux/cgroup.h>
L
Linus Torvalds 已提交
35
#include <linux/syscalls.h>
36
#include <linux/signal.h>
37
#include <linux/posix-timers.h>
M
Matt Helsley 已提交
38
#include <linux/cn_proc.h>
39
#include <linux/mutex.h>
40
#include <linux/futex.h>
41
#include <linux/compat.h>
42
#include <linux/pipe_fs_i.h>
43
#include <linux/audit.h> /* for audit_free() */
A
Adrian Bunk 已提交
44
#include <linux/resource.h>
45
#include <linux/blkdev.h>
46
#include <linux/task_io_accounting_ops.h>
L
Linus Torvalds 已提交
47 48 49 50 51 52

#include <asm/uaccess.h>
#include <asm/unistd.h>
#include <asm/pgtable.h>
#include <asm/mmu_context.h>

A
Adrian Bunk 已提交
53 54
static void exit_mm(struct task_struct * tsk);

L
Linus Torvalds 已提交
55 56 57 58 59 60 61
static void __unhash_process(struct task_struct *p)
{
	nr_threads--;
	detach_pid(p, PIDTYPE_PID);
	if (thread_group_leader(p)) {
		detach_pid(p, PIDTYPE_PGID);
		detach_pid(p, PIDTYPE_SID);
62

63
		list_del_rcu(&p->tasks);
64
		__get_cpu_var(process_counts)--;
L
Linus Torvalds 已提交
65
	}
O
Oleg Nesterov 已提交
66
	list_del_rcu(&p->thread_group);
67
	remove_parent(p);
L
Linus Torvalds 已提交
68 69
}

70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92
/*
 * This function expects the tasklist_lock write-locked.
 */
static void __exit_signal(struct task_struct *tsk)
{
	struct signal_struct *sig = tsk->signal;
	struct sighand_struct *sighand;

	BUG_ON(!sig);
	BUG_ON(!atomic_read(&sig->count));

	rcu_read_lock();
	sighand = rcu_dereference(tsk->sighand);
	spin_lock(&sighand->siglock);

	posix_cpu_timers_exit(tsk);
	if (atomic_dec_and_test(&sig->count))
		posix_cpu_timers_exit_group(tsk);
	else {
		/*
		 * If there is any task waiting for the group exit
		 * then notify it:
		 */
93
		if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count)
94
			wake_up_process(sig->group_exit_task);
95

96 97 98 99 100 101 102 103 104 105 106 107 108 109
		if (tsk == sig->curr_target)
			sig->curr_target = next_thread(tsk);
		/*
		 * Accumulate here the counters for all threads but the
		 * group leader as they die, so they can be added into
		 * the process-wide totals when those are taken.
		 * The group leader stays around as a zombie as long
		 * as there are other threads.  When it gets reaped,
		 * the exit.c code will add its counts into these totals.
		 * We won't ever get here for the group leader, since it
		 * will have been the last reference on the signal_struct.
		 */
		sig->utime = cputime_add(sig->utime, tsk->utime);
		sig->stime = cputime_add(sig->stime, tsk->stime);
110
		sig->gtime = cputime_add(sig->gtime, tsk->gtime);
111 112 113 114
		sig->min_flt += tsk->min_flt;
		sig->maj_flt += tsk->maj_flt;
		sig->nvcsw += tsk->nvcsw;
		sig->nivcsw += tsk->nivcsw;
115 116
		sig->inblock += task_io_get_inblock(tsk);
		sig->oublock += task_io_get_oublock(tsk);
117
		sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
118 119 120
		sig = NULL; /* Marker for below. */
	}

121 122
	__unhash_process(tsk);

123
	tsk->signal = NULL;
124
	tsk->sighand = NULL;
125 126 127
	spin_unlock(&sighand->siglock);
	rcu_read_unlock();

128
	__cleanup_sighand(sighand);
129 130 131 132
	clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
	flush_sigqueue(&tsk->pending);
	if (sig) {
		flush_sigqueue(&sig->shared_pending);
133
		taskstats_tgid_free(sig);
134 135 136 137
		__cleanup_signal(sig);
	}
}

138 139 140 141 142
static void delayed_put_task_struct(struct rcu_head *rhp)
{
	put_task_struct(container_of(rhp, struct task_struct, rcu));
}

L
Linus Torvalds 已提交
143 144
void release_task(struct task_struct * p)
{
145
	struct task_struct *leader;
L
Linus Torvalds 已提交
146
	int zap_leader;
147
repeat:
L
Linus Torvalds 已提交
148
	atomic_dec(&p->user->processes);
149
	proc_flush_task(p);
L
Linus Torvalds 已提交
150
	write_lock_irq(&tasklist_lock);
151
	ptrace_unlink(p);
L
Linus Torvalds 已提交
152 153
	BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
	__exit_signal(p);
154

L
Linus Torvalds 已提交
155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177
	/*
	 * If we are the last non-leader member of the thread
	 * group, and the leader is zombie, then notify the
	 * group leader's parent process. (if it wants notification.)
	 */
	zap_leader = 0;
	leader = p->group_leader;
	if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
		BUG_ON(leader->exit_signal == -1);
		do_notify_parent(leader, leader->exit_signal);
		/*
		 * If we were the last child thread and the leader has
		 * exited already, and the leader's parent ignores SIGCHLD,
		 * then we are the one who should release the leader.
		 *
		 * do_notify_parent() will have marked it self-reaping in
		 * that case.
		 */
		zap_leader = (leader->exit_signal == -1);
	}

	write_unlock_irq(&tasklist_lock);
	release_thread(p);
178
	call_rcu(&p->rcu, delayed_put_task_struct);
L
Linus Torvalds 已提交
179 180 181 182 183 184 185 186 187 188

	p = leader;
	if (unlikely(zap_leader))
		goto repeat;
}

/*
 * This checks not only the pgrp, but falls back on the pid if no
 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
 * without this...
189 190
 *
 * The caller must hold rcu lock or the tasklist lock.
L
Linus Torvalds 已提交
191
 */
192
struct pid *session_of_pgrp(struct pid *pgrp)
L
Linus Torvalds 已提交
193 194
{
	struct task_struct *p;
195
	struct pid *sid = NULL;
196

197
	p = pid_task(pgrp, PIDTYPE_PGID);
198
	if (p == NULL)
199
		p = pid_task(pgrp, PIDTYPE_PID);
200
	if (p != NULL)
201
		sid = task_session(p);
202

L
Linus Torvalds 已提交
203 204 205 206 207 208 209 210 211 212 213
	return sid;
}

/*
 * Determine if a process group is "orphaned", according to the POSIX
 * definition in 2.2.2.52.  Orphaned process groups are not to be affected
 * by terminal-generated stop signals.  Newly orphaned process groups are
 * to receive a SIGHUP and a SIGCONT.
 *
 * "I ask you, have you ever known what it is to be an orphan?"
 */
214
static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
L
Linus Torvalds 已提交
215 216 217 218
{
	struct task_struct *p;
	int ret = 1;

219
	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
L
Linus Torvalds 已提交
220 221
		if (p == ignored_task
				|| p->exit_state
222
				|| is_global_init(p->real_parent))
L
Linus Torvalds 已提交
223
			continue;
224 225
		if (task_pgrp(p->real_parent) != pgrp &&
		    task_session(p->real_parent) == task_session(p)) {
L
Linus Torvalds 已提交
226 227 228
			ret = 0;
			break;
		}
229
	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
L
Linus Torvalds 已提交
230 231 232
	return ret;	/* (sighing) "Often!" */
}

233
int is_current_pgrp_orphaned(void)
L
Linus Torvalds 已提交
234 235 236 237
{
	int retval;

	read_lock(&tasklist_lock);
238
	retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
L
Linus Torvalds 已提交
239 240 241 242 243
	read_unlock(&tasklist_lock);

	return retval;
}

244
static int has_stopped_jobs(struct pid *pgrp)
L
Linus Torvalds 已提交
245 246 247 248
{
	int retval = 0;
	struct task_struct *p;

249
	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
M
Matthew Wilcox 已提交
250
		if (!task_is_stopped(p))
L
Linus Torvalds 已提交
251 252 253
			continue;
		retval = 1;
		break;
254
	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
L
Linus Torvalds 已提交
255 256 257 258
	return retval;
}

/**
259
 * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
L
Linus Torvalds 已提交
260 261
 *
 * If a kernel thread is launched as a result of a system call, or if
262 263
 * it ever exits, it should generally reparent itself to kthreadd so it
 * isn't in the way of other processes and is correctly cleaned up on exit.
L
Linus Torvalds 已提交
264 265 266 267
 *
 * The various task state such as scheduling policy and priority may have
 * been inherited from a user process, so we reset them to sane values here.
 *
268
 * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
L
Linus Torvalds 已提交
269
 */
270
static void reparent_to_kthreadd(void)
L
Linus Torvalds 已提交
271 272 273 274 275
{
	write_lock_irq(&tasklist_lock);

	ptrace_unlink(current);
	/* Reparent to init */
276
	remove_parent(current);
277
	current->real_parent = current->parent = kthreadd_task;
278
	add_parent(current);
L
Linus Torvalds 已提交
279 280 281 282

	/* Set the exit signal to SIGCHLD so we signal init on exit */
	current->exit_signal = SIGCHLD;

283
	if (task_nice(current) < 0)
L
Linus Torvalds 已提交
284 285 286 287 288 289 290 291 292 293 294 295
		set_user_nice(current, 0);
	/* cpus_allowed? */
	/* rt_priority? */
	/* signals? */
	security_task_reparent_to_init(current);
	memcpy(current->signal->rlim, init_task.signal->rlim,
	       sizeof(current->signal->rlim));
	atomic_inc(&(INIT_USER->__count));
	write_unlock_irq(&tasklist_lock);
	switch_uid(INIT_USER);
}

296
void __set_special_pids(struct pid *pid)
L
Linus Torvalds 已提交
297
{
298
	struct task_struct *curr = current->group_leader;
299
	pid_t nr = pid_nr(pid);
L
Linus Torvalds 已提交
300

301
	if (task_session(curr) != pid) {
L
Linus Torvalds 已提交
302
		detach_pid(curr, PIDTYPE_SID);
303 304
		attach_pid(curr, PIDTYPE_SID, pid);
		set_task_session(curr, nr);
L
Linus Torvalds 已提交
305
	}
306
	if (task_pgrp(curr) != pid) {
L
Linus Torvalds 已提交
307
		detach_pid(curr, PIDTYPE_PGID);
308 309
		attach_pid(curr, PIDTYPE_PGID, pid);
		set_task_pgrp(curr, nr);
L
Linus Torvalds 已提交
310 311 312
	}
}

313
static void set_special_pids(struct pid *pid)
L
Linus Torvalds 已提交
314 315
{
	write_lock_irq(&tasklist_lock);
316
	__set_special_pids(pid);
L
Linus Torvalds 已提交
317 318 319 320 321 322 323 324 325 326
	write_unlock_irq(&tasklist_lock);
}

/*
 * Let kernel threads use this to say that they
 * allow a certain signal (since daemonize() will
 * have disabled all of them by default).
 */
int allow_signal(int sig)
{
327
	if (!valid_signal(sig) || sig < 1)
L
Linus Torvalds 已提交
328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347
		return -EINVAL;

	spin_lock_irq(&current->sighand->siglock);
	sigdelset(&current->blocked, sig);
	if (!current->mm) {
		/* Kernel threads handle their own signals.
		   Let the signal code know it'll be handled, so
		   that they don't get converted to SIGKILL or
		   just silently dropped */
		current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
	}
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);
	return 0;
}

EXPORT_SYMBOL(allow_signal);

int disallow_signal(int sig)
{
348
	if (!valid_signal(sig) || sig < 1)
L
Linus Torvalds 已提交
349 350 351
		return -EINVAL;

	spin_lock_irq(&current->sighand->siglock);
352
	current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
L
Linus Torvalds 已提交
353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);
	return 0;
}

EXPORT_SYMBOL(disallow_signal);

/*
 *	Put all the gunge required to become a kernel thread without
 *	attached user resources in one place where it belongs.
 */

void daemonize(const char *name, ...)
{
	va_list args;
	struct fs_struct *fs;
	sigset_t blocked;

	va_start(args, name);
	vsnprintf(current->comm, sizeof(current->comm), name, args);
	va_end(args);

	/*
	 * If we were started as result of loading a module, close all of the
	 * user space pages.  We don't need them, and if we didn't close them
	 * they would be locked into memory.
	 */
	exit_mm(current);
381 382 383 384 385
	/*
	 * We don't want to have TIF_FREEZE set if the system-wide hibernation
	 * or suspend transition begins right now.
	 */
	current->flags |= PF_NOFREEZE;
L
Linus Torvalds 已提交
386

387 388 389 390
	if (current->nsproxy != &init_nsproxy) {
		get_nsproxy(&init_nsproxy);
		switch_task_namespaces(current, &init_nsproxy);
	}
391
	set_special_pids(&init_struct_pid);
392
	proc_clear_tty(current);
L
Linus Torvalds 已提交
393 394 395 396 397 398 399 400 401 402 403 404

	/* Block and flush all signals */
	sigfillset(&blocked);
	sigprocmask(SIG_BLOCK, &blocked, NULL);
	flush_signals(current);

	/* Become as one with the init task */

	exit_fs(current);	/* current->fs->count--; */
	fs = init_task.fs;
	current->fs = fs;
	atomic_inc(&fs->count);
S
Serge E. Hallyn 已提交
405

406
	exit_files(current);
L
Linus Torvalds 已提交
407 408 409
	current->files = init_task.files;
	atomic_inc(&current->files->count);

410
	reparent_to_kthreadd();
L
Linus Torvalds 已提交
411 412 413 414
}

EXPORT_SYMBOL(daemonize);

415
static void close_files(struct files_struct * files)
L
Linus Torvalds 已提交
416 417
{
	int i, j;
418
	struct fdtable *fdt;
L
Linus Torvalds 已提交
419 420

	j = 0;
421 422 423 424 425 426

	/*
	 * It is safe to dereference the fd table without RCU or
	 * ->file_lock because this is the last reference to the
	 * files structure.
	 */
427
	fdt = files_fdtable(files);
L
Linus Torvalds 已提交
428 429 430
	for (;;) {
		unsigned long set;
		i = j * __NFDBITS;
431
		if (i >= fdt->max_fds)
L
Linus Torvalds 已提交
432
			break;
433
		set = fdt->open_fds->fds_bits[j++];
L
Linus Torvalds 已提交
434 435
		while (set) {
			if (set & 1) {
436
				struct file * file = xchg(&fdt->fd[i], NULL);
437
				if (file) {
L
Linus Torvalds 已提交
438
					filp_close(file, files);
439 440
					cond_resched();
				}
L
Linus Torvalds 已提交
441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462
			}
			i++;
			set >>= 1;
		}
	}
}

struct files_struct *get_files_struct(struct task_struct *task)
{
	struct files_struct *files;

	task_lock(task);
	files = task->files;
	if (files)
		atomic_inc(&files->count);
	task_unlock(task);

	return files;
}

void fastcall put_files_struct(struct files_struct *files)
{
463 464
	struct fdtable *fdt;

L
Linus Torvalds 已提交
465 466 467 468
	if (atomic_dec_and_test(&files->count)) {
		close_files(files);
		/*
		 * Free the fd and fdset arrays if we expanded them.
469 470 471
		 * If the fdtable was embedded, pass files for freeing
		 * at the end of the RCU grace period. Otherwise,
		 * you can free files immediately.
L
Linus Torvalds 已提交
472
		 */
473
		fdt = files_fdtable(files);
474
		if (fdt != &files->fdtab)
475
			kmem_cache_free(files_cachep, files);
476
		free_fdtable(fdt);
L
Linus Torvalds 已提交
477 478 479 480 481
	}
}

EXPORT_SYMBOL(put_files_struct);

482 483 484 485 486 487 488 489 490 491 492 493
void reset_files_struct(struct task_struct *tsk, struct files_struct *files)
{
	struct files_struct *old;

	old = tsk->files;
	task_lock(tsk);
	tsk->files = files;
	task_unlock(tsk);
	put_files_struct(old);
}
EXPORT_SYMBOL(reset_files_struct);

A
Alexey Dobriyan 已提交
494
static void __exit_files(struct task_struct *tsk)
L
Linus Torvalds 已提交
495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510
{
	struct files_struct * files = tsk->files;

	if (files) {
		task_lock(tsk);
		tsk->files = NULL;
		task_unlock(tsk);
		put_files_struct(files);
	}
}

void exit_files(struct task_struct *tsk)
{
	__exit_files(tsk);
}

A
Alexey Dobriyan 已提交
511
static void __put_fs_struct(struct fs_struct *fs)
L
Linus Torvalds 已提交
512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531
{
	/* No need to hold fs->lock if we are killing it */
	if (atomic_dec_and_test(&fs->count)) {
		dput(fs->root);
		mntput(fs->rootmnt);
		dput(fs->pwd);
		mntput(fs->pwdmnt);
		if (fs->altroot) {
			dput(fs->altroot);
			mntput(fs->altrootmnt);
		}
		kmem_cache_free(fs_cachep, fs);
	}
}

void put_fs_struct(struct fs_struct *fs)
{
	__put_fs_struct(fs);
}

A
Alexey Dobriyan 已提交
532
static void __exit_fs(struct task_struct *tsk)
L
Linus Torvalds 已提交
533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554
{
	struct fs_struct * fs = tsk->fs;

	if (fs) {
		task_lock(tsk);
		tsk->fs = NULL;
		task_unlock(tsk);
		__put_fs_struct(fs);
	}
}

void exit_fs(struct task_struct *tsk)
{
	__exit_fs(tsk);
}

EXPORT_SYMBOL_GPL(exit_fs);

/*
 * Turn us into a lazy TLB process if we
 * aren't already..
 */
A
Adrian Bunk 已提交
555
static void exit_mm(struct task_struct * tsk)
L
Linus Torvalds 已提交
556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580
{
	struct mm_struct *mm = tsk->mm;

	mm_release(tsk, mm);
	if (!mm)
		return;
	/*
	 * Serialize with any possible pending coredump.
	 * We must hold mmap_sem around checking core_waiters
	 * and clearing tsk->mm.  The core-inducing thread
	 * will increment core_waiters for each thread in the
	 * group with ->mm != NULL.
	 */
	down_read(&mm->mmap_sem);
	if (mm->core_waiters) {
		up_read(&mm->mmap_sem);
		down_write(&mm->mmap_sem);
		if (!--mm->core_waiters)
			complete(mm->core_startup_done);
		up_write(&mm->mmap_sem);

		wait_for_completion(&mm->core_done);
		down_read(&mm->mmap_sem);
	}
	atomic_inc(&mm->mm_count);
E
Eric Sesterhenn 已提交
581
	BUG_ON(mm != tsk->active_mm);
L
Linus Torvalds 已提交
582 583 584 585 586
	/* more a memory barrier than a real lock */
	task_lock(tsk);
	tsk->mm = NULL;
	up_read(&mm->mmap_sem);
	enter_lazy_tlb(mm, current);
587 588
	/* We don't want this task to be frozen prematurely */
	clear_freeze_flag(tsk);
L
Linus Torvalds 已提交
589 590 591 592
	task_unlock(tsk);
	mmput(mm);
}

593 594
static void
reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
L
Linus Torvalds 已提交
595
{
596 597 598 599
	if (p->pdeath_signal)
		/* We already hold the tasklist_lock here.  */
		group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);

L
Linus Torvalds 已提交
600 601 602 603 604 605 606 607 608 609 610
	/* Move the child from its dying parent to the new one.  */
	if (unlikely(traced)) {
		/* Preserve ptrace links if someone else is tracing this child.  */
		list_del_init(&p->ptrace_list);
		if (p->parent != p->real_parent)
			list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
	} else {
		/* If this child is being traced, then we're the one tracing it
		 * anyway, so let go of it.
		 */
		p->ptrace = 0;
611
		remove_parent(p);
L
Linus Torvalds 已提交
612
		p->parent = p->real_parent;
613
		add_parent(p);
L
Linus Torvalds 已提交
614

M
Matthew Wilcox 已提交
615
		if (task_is_traced(p)) {
L
Linus Torvalds 已提交
616 617 618 619 620 621 622 623 624
			/*
			 * If it was at a trace stop, turn it into
			 * a normal stop since it's no longer being
			 * traced.
			 */
			ptrace_untrace(p);
		}
	}

625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641
	/* If this is a threaded reparent there is no need to
	 * notify anyone anything has happened.
	 */
	if (p->real_parent->group_leader == father->group_leader)
		return;

	/* We don't want people slaying init.  */
	if (p->exit_signal != -1)
		p->exit_signal = SIGCHLD;

	/* If we'd notified the old parent about this child's death,
	 * also notify the new parent.
	 */
	if (!traced && p->exit_state == EXIT_ZOMBIE &&
	    p->exit_signal != -1 && thread_group_empty(p))
		do_notify_parent(p, p->exit_signal);

L
Linus Torvalds 已提交
642 643 644 645 646 647
	/*
	 * process group orphan check
	 * Case ii: Our child is in a different pgrp
	 * than we are, and it was the only connection
	 * outside, so the child pgrp is now orphaned.
	 */
648 649 650
	if ((task_pgrp(p) != task_pgrp(father)) &&
	    (task_session(p) == task_session(father))) {
		struct pid *pgrp = task_pgrp(p);
L
Linus Torvalds 已提交
651

652 653
		if (will_become_orphaned_pgrp(pgrp, NULL) &&
		    has_stopped_jobs(pgrp)) {
654 655
			__kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
			__kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
L
Linus Torvalds 已提交
656 657 658 659 660 661 662 663
		}
	}
}

/*
 * When we die, we re-parent all our children.
 * Try to give them to another thread in our thread
 * group, and if no such member exists, give it to
664 665
 * the child reaper process (ie "init") in our pid
 * space.
L
Linus Torvalds 已提交
666
 */
667
static void forget_original_parent(struct task_struct *father)
L
Linus Torvalds 已提交
668
{
669
	struct task_struct *p, *n, *reaper = father;
670 671 672 673 674
	struct list_head ptrace_dead;

	INIT_LIST_HEAD(&ptrace_dead);

	write_lock_irq(&tasklist_lock);
L
Linus Torvalds 已提交
675 676 677 678

	do {
		reaper = next_thread(reaper);
		if (reaper == father) {
679
			reaper = task_child_reaper(father);
L
Linus Torvalds 已提交
680 681
			break;
		}
682
	} while (reaper->flags & PF_EXITING);
L
Linus Torvalds 已提交
683 684 685 686 687 688 689 690 691

	/*
	 * There are only two places where our children can be:
	 *
	 * - in our child list
	 * - in our ptraced child list
	 *
	 * Search them and reparent children.
	 */
692
	list_for_each_entry_safe(p, n, &father->children, sibling) {
L
Linus Torvalds 已提交
693 694 695 696 697 698 699 700 701
		int ptrace;

		ptrace = p->ptrace;

		/* if father isn't the real parent, then ptrace must be enabled */
		BUG_ON(father != p->real_parent && !ptrace);

		if (father == p->real_parent) {
			/* reparent with a reaper, real father it's us */
702
			p->real_parent = reaper;
L
Linus Torvalds 已提交
703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718
			reparent_thread(p, father, 0);
		} else {
			/* reparent ptraced task to its real parent */
			__ptrace_unlink (p);
			if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
			    thread_group_empty(p))
				do_notify_parent(p, p->exit_signal);
		}

		/*
		 * if the ptraced child is a zombie with exit_signal == -1
		 * we must collect it before we exit, or it will remain
		 * zombie forever since we prevented it from self-reap itself
		 * while it was being traced by us, to be able to see it in wait4.
		 */
		if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
719
			list_add(&p->ptrace_list, &ptrace_dead);
L
Linus Torvalds 已提交
720
	}
721

722
	list_for_each_entry_safe(p, n, &father->ptrace_children, ptrace_list) {
723
		p->real_parent = reaper;
L
Linus Torvalds 已提交
724 725
		reparent_thread(p, father, 1);
	}
726 727 728 729 730 731 732 733 734 735

	write_unlock_irq(&tasklist_lock);
	BUG_ON(!list_empty(&father->children));
	BUG_ON(!list_empty(&father->ptrace_children));

	list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_list) {
		list_del_init(&p->ptrace_list);
		release_task(p);
	}

L
Linus Torvalds 已提交
736 737 738 739 740 741 742 743 744 745
}

/*
 * Send signals to all our closest relatives so that they know
 * to properly mourn us..
 */
static void exit_notify(struct task_struct *tsk)
{
	int state;
	struct task_struct *t;
746
	struct pid *pgrp;
L
Linus Torvalds 已提交
747 748 749 750 751 752 753 754 755 756 757 758 759 760

	if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
	    && !thread_group_empty(tsk)) {
		/*
		 * This occurs when there was a race between our exit
		 * syscall and a group signal choosing us as the one to
		 * wake up.  It could be that we are the only thread
		 * alerted to check for pending signals, but another thread
		 * should be woken now to take the signal since we will not.
		 * Now we'll wake all the threads in the group just to make
		 * sure someone gets all the pending signals.
		 */
		spin_lock_irq(&tsk->sighand->siglock);
		for (t = next_thread(tsk); t != tsk; t = next_thread(t))
R
Roland McGrath 已提交
761 762
			if (!signal_pending(t) && !(t->flags & PF_EXITING))
				recalc_sigpending_and_wake(t);
L
Linus Torvalds 已提交
763 764 765 766 767 768 769 770 771 772 773
		spin_unlock_irq(&tsk->sighand->siglock);
	}

	/*
	 * This does two things:
	 *
  	 * A.  Make init inherit all the child processes
	 * B.  Check to see if any process groups have become orphaned
	 *	as a result of our exiting, and if they have any stopped
	 *	jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
	 */
774
	forget_original_parent(tsk);
775
	exit_task_namespaces(tsk);
L
Linus Torvalds 已提交
776

777
	write_lock_irq(&tasklist_lock);
L
Linus Torvalds 已提交
778 779 780 781 782 783 784 785 786 787
	/*
	 * Check to see if any process groups have become orphaned
	 * as a result of our exiting, and if they have any stopped
	 * jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
	 *
	 * Case i: Our father is in a different pgrp than we are
	 * and we were the only connection outside, so our pgrp
	 * is about to become orphaned.
	 */
	t = tsk->real_parent;
788

789 790
	pgrp = task_pgrp(tsk);
	if ((task_pgrp(t) != pgrp) &&
791
	    (task_session(t) == task_session(tsk)) &&
792 793 794 795
	    will_become_orphaned_pgrp(pgrp, tsk) &&
	    has_stopped_jobs(pgrp)) {
		__kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
		__kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
L
Linus Torvalds 已提交
796 797
	}

798
	/* Let father know we died
L
Linus Torvalds 已提交
799 800
	 *
	 * Thread signals are configurable, but you aren't going to use
801
	 * that to send signals to arbitary processes.
L
Linus Torvalds 已提交
802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830
	 * That stops right now.
	 *
	 * If the parent exec id doesn't match the exec id we saved
	 * when we started then we know the parent has changed security
	 * domain.
	 *
	 * If our self_exec id doesn't match our parent_exec_id then
	 * we have changed execution domain as these two values started
	 * the same after a fork.
	 */
	if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
	    ( tsk->parent_exec_id != t->self_exec_id  ||
	      tsk->self_exec_id != tsk->parent_exec_id)
	    && !capable(CAP_KILL))
		tsk->exit_signal = SIGCHLD;


	/* If something other than our normal parent is ptracing us, then
	 * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
	 * only has special meaning to our real parent.
	 */
	if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
		int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
		do_notify_parent(tsk, signal);
	} else if (tsk->ptrace) {
		do_notify_parent(tsk, SIGCHLD);
	}

	state = EXIT_ZOMBIE;
831
	if (tsk->exit_signal == -1 && likely(!tsk->ptrace))
L
Linus Torvalds 已提交
832 833 834
		state = EXIT_DEAD;
	tsk->exit_state = state;

835 836 837 838 839
	if (thread_group_leader(tsk) &&
	    tsk->signal->notify_count < 0 &&
	    tsk->signal->group_exit_task)
		wake_up_process(tsk->signal->group_exit_task);

L
Linus Torvalds 已提交
840 841 842 843 844 845 846
	write_unlock_irq(&tasklist_lock);

	/* If the process is dead, release it - nobody will wait for it */
	if (state == EXIT_DEAD)
		release_task(tsk);
}

847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874
#ifdef CONFIG_DEBUG_STACK_USAGE
static void check_stack_usage(void)
{
	static DEFINE_SPINLOCK(low_water_lock);
	static int lowest_to_date = THREAD_SIZE;
	unsigned long *n = end_of_stack(current);
	unsigned long free;

	while (*n == 0)
		n++;
	free = (unsigned long)n - (unsigned long)end_of_stack(current);

	if (free >= lowest_to_date)
		return;

	spin_lock(&low_water_lock);
	if (free < lowest_to_date) {
		printk(KERN_WARNING "%s used greatest stack depth: %lu bytes "
				"left\n",
				current->comm, free);
		lowest_to_date = free;
	}
	spin_unlock(&low_water_lock);
}
#else
static inline void check_stack_usage(void) {}
#endif

875 876
static inline void exit_child_reaper(struct task_struct *tsk)
{
877
	if (likely(tsk->group_leader != task_child_reaper(tsk)))
878 879
		return;

880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905
	if (tsk->nsproxy->pid_ns == &init_pid_ns)
		panic("Attempted to kill init!");

	/*
	 * @tsk is the last thread in the 'cgroup-init' and is exiting.
	 * Terminate all remaining processes in the namespace and reap them
	 * before exiting @tsk.
	 *
	 * Note that @tsk (last thread of cgroup-init) may not necessarily
	 * be the child-reaper (i.e main thread of cgroup-init) of the
	 * namespace i.e the child_reaper may have already exited.
	 *
	 * Even after a child_reaper exits, we let it inherit orphaned children,
	 * because, pid_ns->child_reaper remains valid as long as there is
	 * at least one living sub-thread in the cgroup init.

	 * This living sub-thread of the cgroup-init will be notified when
	 * a child inherited by the 'child-reaper' exits (do_notify_parent()
	 * uses __group_send_sig_info()). Further, when reaping child processes,
	 * do_wait() iterates over children of all living sub threads.

	 * i.e even though 'child_reaper' thread is listed as the parent of the
	 * orphaned children, any living sub-thread in the cgroup-init can
	 * perform the role of the child_reaper.
	 */
	zap_pid_ns_processes(tsk->nsproxy->pid_ns);
906 907
}

L
Linus Torvalds 已提交
908 909 910 911 912 913 914
fastcall NORET_TYPE void do_exit(long code)
{
	struct task_struct *tsk = current;
	int group_dead;

	profile_task_exit(tsk);

915 916
	WARN_ON(atomic_read(&tsk->fs_excl));

L
Linus Torvalds 已提交
917 918 919 920 921 922 923 924 925 926
	if (unlikely(in_interrupt()))
		panic("Aiee, killing interrupt handler!");
	if (unlikely(!tsk->pid))
		panic("Attempted to kill the idle task!");

	if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
		current->ptrace_message = code;
		ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
	}

927 928 929 930 931 932 933
	/*
	 * We're taking recursive faults here in do_exit. Safest is to just
	 * leave this task alone and wait for reboot.
	 */
	if (unlikely(tsk->flags & PF_EXITING)) {
		printk(KERN_ALERT
			"Fixing recursive fault but reboot is needed!\n");
934 935 936 937 938 939 940 941 942 943
		/*
		 * We can do this unlocked here. The futex code uses
		 * this flag just to verify whether the pi state
		 * cleanup has been done or not. In the worst case it
		 * loops once more. We pretend that the cleanup was
		 * done as there is no way to return. Either the
		 * OWNER_DIED bit is set by now or we push the blocked
		 * task into the wait for ever nirwana as well.
		 */
		tsk->flags |= PF_EXITPIDONE;
944 945
		if (tsk->io_context)
			exit_io_context();
946 947 948 949
		set_current_state(TASK_UNINTERRUPTIBLE);
		schedule();
	}

950
	tsk->flags |= PF_EXITING;
951 952 953 954
	/*
	 * tsk->flags are checked in the futex code to protect against
	 * an exiting task cleaning up the robust pi futexes.
	 */
955 956
	smp_mb();
	spin_unlock_wait(&tsk->pi_lock);
L
Linus Torvalds 已提交
957 958 959

	if (unlikely(in_atomic()))
		printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
960
				current->comm, task_pid_nr(current),
L
Linus Torvalds 已提交
961 962 963
				preempt_count());

	acct_update_integrals(tsk);
964 965 966 967
	if (tsk->mm) {
		update_hiwater_rss(tsk->mm);
		update_hiwater_vm(tsk->mm);
	}
L
Linus Torvalds 已提交
968
	group_dead = atomic_dec_and_test(&tsk->signal->live);
969
	if (group_dead) {
970
		exit_child_reaper(tsk);
971
		hrtimer_cancel(&tsk->signal->real_timer);
972
		exit_itimers(tsk->signal);
973
	}
974
	acct_collect(code, group_dead);
975
#ifdef CONFIG_FUTEX
976 977
	if (unlikely(tsk->robust_list))
		exit_robust_list(tsk);
978
#ifdef CONFIG_COMPAT
979 980
	if (unlikely(tsk->compat_robust_list))
		compat_exit_robust_list(tsk);
981
#endif
982
#endif
M
Miloslav Trmac 已提交
983 984
	if (group_dead)
		tty_audit_exit();
985 986
	if (unlikely(tsk->audit_context))
		audit_free(tsk);
987

988
	tsk->exit_code = code;
989
	taskstats_exit(tsk, group_dead);
990

L
Linus Torvalds 已提交
991 992
	exit_mm(tsk);

993
	if (group_dead)
994
		acct_process();
L
Linus Torvalds 已提交
995 996 997
	exit_sem(tsk);
	__exit_files(tsk);
	__exit_fs(tsk);
998
	check_stack_usage();
L
Linus Torvalds 已提交
999
	exit_thread();
1000
	cgroup_exit(tsk, 1);
L
Linus Torvalds 已提交
1001 1002 1003 1004 1005
	exit_keys(tsk);

	if (group_dead && tsk->signal->leader)
		disassociate_ctty(1);

A
Al Viro 已提交
1006
	module_put(task_thread_info(tsk)->exec_domain->module);
L
Linus Torvalds 已提交
1007 1008 1009
	if (tsk->binfmt)
		module_put(tsk->binfmt->module);

M
Matt Helsley 已提交
1010
	proc_exit_connector(tsk);
1011
	exit_notify(tsk);
L
Linus Torvalds 已提交
1012 1013 1014 1015
#ifdef CONFIG_NUMA
	mpol_free(tsk->mempolicy);
	tsk->mempolicy = NULL;
#endif
1016
#ifdef CONFIG_FUTEX
1017 1018 1019 1020 1021 1022 1023 1024
	/*
	 * This must happen late, after the PID is not
	 * hashed anymore:
	 */
	if (unlikely(!list_empty(&tsk->pi_state_list)))
		exit_pi_state_list(tsk);
	if (unlikely(current->pi_state_cache))
		kfree(current->pi_state_cache);
1025
#endif
1026
	/*
1027
	 * Make sure we are holding no locks:
1028
	 */
1029
	debug_check_no_locks_held(tsk);
1030 1031 1032 1033 1034 1035
	/*
	 * We can do this unlocked here. The futex code uses this flag
	 * just to verify whether the pi state cleanup has been done
	 * or not. In the worst case it loops once more.
	 */
	tsk->flags |= PF_EXITPIDONE;
L
Linus Torvalds 已提交
1036

1037 1038 1039
	if (tsk->io_context)
		exit_io_context();

1040 1041 1042
	if (tsk->splice_pipe)
		__free_pipe_info(tsk->splice_pipe);

C
Coywolf Qi Hunt 已提交
1043
	preempt_disable();
O
Oleg Nesterov 已提交
1044
	/* causes final put_task_struct in finish_task_switch(). */
1045
	tsk->state = TASK_DEAD;
C
Coywolf Qi Hunt 已提交
1046

L
Linus Torvalds 已提交
1047 1048 1049
	schedule();
	BUG();
	/* Avoid "noreturn function does return".  */
A
Alan Cox 已提交
1050 1051
	for (;;)
		cpu_relax();	/* For when BUG is null */
L
Linus Torvalds 已提交
1052 1053
}

1054 1055
EXPORT_SYMBOL_GPL(do_exit);

L
Linus Torvalds 已提交
1056 1057 1058 1059
NORET_TYPE void complete_and_exit(struct completion *comp, long code)
{
	if (comp)
		complete(comp);
O
Oleg Nesterov 已提交
1060

L
Linus Torvalds 已提交
1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085
	do_exit(code);
}

EXPORT_SYMBOL(complete_and_exit);

asmlinkage long sys_exit(int error_code)
{
	do_exit((error_code&0xff)<<8);
}

/*
 * Take down every thread in the group.  This is called by fatal signals
 * as well as by sys_exit_group (below).
 */
NORET_TYPE void
do_group_exit(int exit_code)
{
	BUG_ON(exit_code & 0x80); /* core dumps don't get here */

	if (current->signal->flags & SIGNAL_GROUP_EXIT)
		exit_code = current->signal->group_exit_code;
	else if (!thread_group_empty(current)) {
		struct signal_struct *const sig = current->signal;
		struct sighand_struct *const sighand = current->sighand;
		spin_lock_irq(&sighand->siglock);
1086
		if (signal_group_exit(sig))
L
Linus Torvalds 已提交
1087 1088 1089 1090
			/* Another thread got here before we took the lock.  */
			exit_code = sig->group_exit_code;
		else {
			sig->group_exit_code = exit_code;
1091
			sig->flags = SIGNAL_GROUP_EXIT;
L
Linus Torvalds 已提交
1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110
			zap_other_threads(current);
		}
		spin_unlock_irq(&sighand->siglock);
	}

	do_exit(exit_code);
	/* NOTREACHED */
}

/*
 * this kills every thread in the thread group. Note that any externally
 * wait4()-ing process will get the correct exit code - even if this
 * thread is not the thread group leader.
 */
asmlinkage void sys_exit_group(int error_code)
{
	do_group_exit((error_code & 0xff) << 8);
}

1111
static int eligible_child(pid_t pid, int options, struct task_struct *p)
L
Linus Torvalds 已提交
1112
{
1113
	int err;
1114
	struct pid_namespace *ns;
1115

1116
	ns = current->nsproxy->pid_ns;
L
Linus Torvalds 已提交
1117
	if (pid > 0) {
1118
		if (task_pid_nr_ns(p, ns) != pid)
L
Linus Torvalds 已提交
1119 1120
			return 0;
	} else if (!pid) {
1121
		if (task_pgrp_nr_ns(p, ns) != task_pgrp_vnr(current))
L
Linus Torvalds 已提交
1122 1123
			return 0;
	} else if (pid != -1) {
1124
		if (task_pgrp_nr_ns(p, ns) != -pid)
L
Linus Torvalds 已提交
1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143
			return 0;
	}

	/*
	 * Do not consider detached threads that are
	 * not ptraced:
	 */
	if (p->exit_signal == -1 && !p->ptrace)
		return 0;

	/* Wait for all children (clone and not) if __WALL is set;
	 * otherwise, wait for clone children *only* if __WCLONE is
	 * set; otherwise, wait for non-clone children *only*.  (Note:
	 * A "clone" child here is one that reports to its parent
	 * using a signal other than SIGCHLD.) */
	if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
	    && !(options & __WALL))
		return 0;

1144
	err = security_task_wait(p);
O
Oleg Nesterov 已提交
1145 1146
	if (likely(!err))
		return 1;
L
Linus Torvalds 已提交
1147

O
Oleg Nesterov 已提交
1148 1149 1150 1151 1152
	if (pid <= 0)
		return 0;
	/* This child was explicitly requested, abort */
	read_unlock(&tasklist_lock);
	return err;
L
Linus Torvalds 已提交
1153 1154
}

1155
static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
L
Linus Torvalds 已提交
1156 1157 1158 1159 1160
			       int why, int status,
			       struct siginfo __user *infop,
			       struct rusage __user *rusagep)
{
	int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1161

L
Linus Torvalds 已提交
1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185
	put_task_struct(p);
	if (!retval)
		retval = put_user(SIGCHLD, &infop->si_signo);
	if (!retval)
		retval = put_user(0, &infop->si_errno);
	if (!retval)
		retval = put_user((short)why, &infop->si_code);
	if (!retval)
		retval = put_user(pid, &infop->si_pid);
	if (!retval)
		retval = put_user(uid, &infop->si_uid);
	if (!retval)
		retval = put_user(status, &infop->si_status);
	if (!retval)
		retval = pid;
	return retval;
}

/*
 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
 * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
 * the lock and this task is uninteresting.  If we return nonzero, we have
 * released the lock and the system call should return.
 */
1186
static int wait_task_zombie(struct task_struct *p, int noreap,
L
Linus Torvalds 已提交
1187 1188 1189 1190
			    struct siginfo __user *infop,
			    int __user *stat_addr, struct rusage __user *ru)
{
	unsigned long state;
1191
	int retval, status, traced;
1192
	pid_t pid = task_pid_nr_ns(p, current->nsproxy->pid_ns);
L
Linus Torvalds 已提交
1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221

	if (unlikely(noreap)) {
		uid_t uid = p->uid;
		int exit_code = p->exit_code;
		int why, status;

		get_task_struct(p);
		read_unlock(&tasklist_lock);
		if ((exit_code & 0x7f) == 0) {
			why = CLD_EXITED;
			status = exit_code >> 8;
		} else {
			why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
			status = exit_code & 0x7f;
		}
		return wait_noreap_copyout(p, pid, uid, why,
					   status, infop, ru);
	}

	/*
	 * Try to move the task's state to DEAD
	 * only one thread is allowed to do this:
	 */
	state = xchg(&p->exit_state, EXIT_DEAD);
	if (state != EXIT_ZOMBIE) {
		BUG_ON(state != EXIT_DEAD);
		return 0;
	}

1222 1223 1224 1225
	/* traced means p->ptrace, but not vice versa */
	traced = (p->real_parent != p->parent);

	if (likely(!traced)) {
1226 1227 1228
		struct signal_struct *psig;
		struct signal_struct *sig;

L
Linus Torvalds 已提交
1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244
		/*
		 * The resource counters for the group leader are in its
		 * own task_struct.  Those for dead threads in the group
		 * are in its signal_struct, as are those for the child
		 * processes it has previously reaped.  All these
		 * accumulate in the parent's signal_struct c* fields.
		 *
		 * We don't bother to take a lock here to protect these
		 * p->signal fields, because they are only touched by
		 * __exit_signal, which runs with tasklist_lock
		 * write-locked anyway, and so is excluded here.  We do
		 * need to protect the access to p->parent->signal fields,
		 * as other threads in the parent group can be right
		 * here reaping other children at the same time.
		 */
		spin_lock_irq(&p->parent->sighand->siglock);
1245 1246 1247 1248
		psig = p->parent->signal;
		sig = p->signal;
		psig->cutime =
			cputime_add(psig->cutime,
L
Linus Torvalds 已提交
1249
			cputime_add(p->utime,
1250 1251 1252 1253
			cputime_add(sig->utime,
				    sig->cutime)));
		psig->cstime =
			cputime_add(psig->cstime,
L
Linus Torvalds 已提交
1254
			cputime_add(p->stime,
1255 1256
			cputime_add(sig->stime,
				    sig->cstime)));
1257 1258 1259 1260 1261
		psig->cgtime =
			cputime_add(psig->cgtime,
			cputime_add(p->gtime,
			cputime_add(sig->gtime,
				    sig->cgtime)));
1262 1263 1264 1265 1266 1267 1268 1269
		psig->cmin_flt +=
			p->min_flt + sig->min_flt + sig->cmin_flt;
		psig->cmaj_flt +=
			p->maj_flt + sig->maj_flt + sig->cmaj_flt;
		psig->cnvcsw +=
			p->nvcsw + sig->nvcsw + sig->cnvcsw;
		psig->cnivcsw +=
			p->nivcsw + sig->nivcsw + sig->cnivcsw;
1270 1271 1272 1273 1274 1275
		psig->cinblock +=
			task_io_get_inblock(p) +
			sig->inblock + sig->cinblock;
		psig->coublock +=
			task_io_get_oublock(p) +
			sig->oublock + sig->coublock;
L
Linus Torvalds 已提交
1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308
		spin_unlock_irq(&p->parent->sighand->siglock);
	}

	/*
	 * Now we are sure this task is interesting, and no other
	 * thread can reap it because we set its state to EXIT_DEAD.
	 */
	read_unlock(&tasklist_lock);

	retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
	status = (p->signal->flags & SIGNAL_GROUP_EXIT)
		? p->signal->group_exit_code : p->exit_code;
	if (!retval && stat_addr)
		retval = put_user(status, stat_addr);
	if (!retval && infop)
		retval = put_user(SIGCHLD, &infop->si_signo);
	if (!retval && infop)
		retval = put_user(0, &infop->si_errno);
	if (!retval && infop) {
		int why;

		if ((status & 0x7f) == 0) {
			why = CLD_EXITED;
			status >>= 8;
		} else {
			why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
			status &= 0x7f;
		}
		retval = put_user((short)why, &infop->si_code);
		if (!retval)
			retval = put_user(status, &infop->si_status);
	}
	if (!retval && infop)
1309
		retval = put_user(pid, &infop->si_pid);
L
Linus Torvalds 已提交
1310 1311
	if (!retval && infop)
		retval = put_user(p->uid, &infop->si_uid);
1312
	if (!retval)
1313
		retval = pid;
1314 1315

	if (traced) {
L
Linus Torvalds 已提交
1316
		write_lock_irq(&tasklist_lock);
1317 1318 1319 1320 1321 1322 1323 1324 1325
		/* We dropped tasklist, ptracer could die and untrace */
		ptrace_unlink(p);
		/*
		 * If this is not a detached task, notify the parent.
		 * If it's still not detached after that, don't release
		 * it now.
		 */
		if (p->exit_signal != -1) {
			do_notify_parent(p, p->exit_signal);
L
Linus Torvalds 已提交
1326
			if (p->exit_signal != -1) {
1327 1328
				p->exit_state = EXIT_ZOMBIE;
				p = NULL;
L
Linus Torvalds 已提交
1329 1330 1331 1332 1333 1334
			}
		}
		write_unlock_irq(&tasklist_lock);
	}
	if (p != NULL)
		release_task(p);
1335

L
Linus Torvalds 已提交
1336 1337 1338 1339 1340 1341 1342 1343 1344
	return retval;
}

/*
 * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
 * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
 * the lock and this task is uninteresting.  If we return nonzero, we have
 * released the lock and the system call should return.
 */
1345
static int wait_task_stopped(struct task_struct *p,
1346
			     int noreap, struct siginfo __user *infop,
L
Linus Torvalds 已提交
1347 1348
			     int __user *stat_addr, struct rusage __user *ru)
{
1349 1350
	int retval, exit_code, why;
	uid_t uid = 0; /* unneeded, required by compiler */
1351
	pid_t pid;
L
Linus Torvalds 已提交
1352

1353 1354 1355 1356 1357 1358
	exit_code = 0;
	spin_lock_irq(&p->sighand->siglock);

	if (unlikely(!task_is_stopped_or_traced(p)))
		goto unlock_sig;

1359
	if (!(p->ptrace & PT_PTRACED) && p->signal->group_stop_count > 0)
L
Linus Torvalds 已提交
1360 1361 1362 1363
		/*
		 * A group stop is in progress and this is the group leader.
		 * We won't report until all threads have stopped.
		 */
1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376
		goto unlock_sig;

	exit_code = p->exit_code;
	if (!exit_code)
		goto unlock_sig;

	if (!noreap)
		p->exit_code = 0;

	uid = p->uid;
unlock_sig:
	spin_unlock_irq(&p->sighand->siglock);
	if (!exit_code)
L
Linus Torvalds 已提交
1377 1378 1379 1380 1381 1382 1383 1384 1385 1386
		return 0;

	/*
	 * Now we are pretty sure this task is interesting.
	 * Make sure it doesn't get reaped out from under us while we
	 * give up the lock and then examine it below.  We don't want to
	 * keep holding onto the tasklist_lock while we call getrusage and
	 * possibly take page faults for user memory.
	 */
	get_task_struct(p);
1387 1388
	pid = task_pid_nr_ns(p, current->nsproxy->pid_ns);
	why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
L
Linus Torvalds 已提交
1389 1390
	read_unlock(&tasklist_lock);

1391
	if (unlikely(noreap))
L
Linus Torvalds 已提交
1392
		return wait_noreap_copyout(p, pid, uid,
1393
					   why, exit_code,
L
Linus Torvalds 已提交
1394 1395 1396 1397 1398 1399 1400 1401 1402 1403
					   infop, ru);

	retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
	if (!retval && stat_addr)
		retval = put_user((exit_code << 8) | 0x7f, stat_addr);
	if (!retval && infop)
		retval = put_user(SIGCHLD, &infop->si_signo);
	if (!retval && infop)
		retval = put_user(0, &infop->si_errno);
	if (!retval && infop)
1404
		retval = put_user(why, &infop->si_code);
L
Linus Torvalds 已提交
1405 1406 1407
	if (!retval && infop)
		retval = put_user(exit_code, &infop->si_status);
	if (!retval && infop)
1408
		retval = put_user(pid, &infop->si_pid);
L
Linus Torvalds 已提交
1409
	if (!retval && infop)
1410
		retval = put_user(uid, &infop->si_uid);
L
Linus Torvalds 已提交
1411
	if (!retval)
1412
		retval = pid;
L
Linus Torvalds 已提交
1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424
	put_task_struct(p);

	BUG_ON(!retval);
	return retval;
}

/*
 * Handle do_wait work for one task in a live, non-stopped state.
 * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
 * the lock and this task is uninteresting.  If we return nonzero, we have
 * released the lock and the system call should return.
 */
1425
static int wait_task_continued(struct task_struct *p, int noreap,
L
Linus Torvalds 已提交
1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445
			       struct siginfo __user *infop,
			       int __user *stat_addr, struct rusage __user *ru)
{
	int retval;
	pid_t pid;
	uid_t uid;

	if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
		return 0;

	spin_lock_irq(&p->sighand->siglock);
	/* Re-check with the lock held.  */
	if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
		spin_unlock_irq(&p->sighand->siglock);
		return 0;
	}
	if (!noreap)
		p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
	spin_unlock_irq(&p->sighand->siglock);

1446
	pid = task_pid_nr_ns(p, current->nsproxy->pid_ns);
L
Linus Torvalds 已提交
1447 1448 1449 1450 1451 1452 1453 1454 1455 1456
	uid = p->uid;
	get_task_struct(p);
	read_unlock(&tasklist_lock);

	if (!infop) {
		retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
		put_task_struct(p);
		if (!retval && stat_addr)
			retval = put_user(0xffff, stat_addr);
		if (!retval)
1457
			retval = pid;
L
Linus Torvalds 已提交
1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480
	} else {
		retval = wait_noreap_copyout(p, pid, uid,
					     CLD_CONTINUED, SIGCONT,
					     infop, ru);
		BUG_ON(retval == 0);
	}

	return retval;
}

static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
		    int __user *stat_addr, struct rusage __user *ru)
{
	DECLARE_WAITQUEUE(wait, current);
	struct task_struct *tsk;
	int flag, retval;

	add_wait_queue(&current->signal->wait_chldexit,&wait);
repeat:
	/*
	 * We will set this flag if we see any child that might later
	 * match our criteria, even if we are not able to reap it yet.
	 */
O
Oleg Nesterov 已提交
1481
	flag = retval = 0;
L
Linus Torvalds 已提交
1482 1483 1484 1485 1486 1487
	current->state = TASK_INTERRUPTIBLE;
	read_lock(&tasklist_lock);
	tsk = current;
	do {
		struct task_struct *p;

1488
		list_for_each_entry(p, &tsk->children, sibling) {
1489
			int ret = eligible_child(pid, options, p);
L
Linus Torvalds 已提交
1490 1491 1492
			if (!ret)
				continue;

1493
			if (unlikely(ret < 0)) {
O
Oleg Nesterov 已提交
1494 1495
				retval = ret;
			} else if (task_is_stopped_or_traced(p)) {
L
Linus Torvalds 已提交
1496 1497 1498 1499 1500
				/*
				 * It's stopped now, so it might later
				 * continue, exit, or stop again.
				 */
				flag = 1;
O
Oleg Nesterov 已提交
1501 1502 1503
				if (!(p->ptrace & PT_PTRACED) &&
				    !(options & WUNTRACED))
					continue;
M
Matthew Wilcox 已提交
1504

1505
				retval = wait_task_stopped(p,
M
Matthew Wilcox 已提交
1506 1507
						(options & WNOWAIT), infop,
						stat_addr, ru);
1508 1509
			} else if (p->exit_state == EXIT_ZOMBIE &&
					!delay_group_leader(p)) {
M
Matthew Wilcox 已提交
1510
				/*
1511
				 * We don't reap group leaders with subthreads.
M
Matthew Wilcox 已提交
1512 1513
				 */
				if (!likely(options & WEXITED))
L
Linus Torvalds 已提交
1514
					continue;
M
Matthew Wilcox 已提交
1515 1516 1517
				retval = wait_task_zombie(p,
						(options & WNOWAIT), infop,
						stat_addr, ru);
1518
			} else if (p->exit_state != EXIT_DEAD) {
L
Linus Torvalds 已提交
1519 1520 1521 1522 1523 1524 1525
				/*
				 * It's running now, so it might later
				 * exit, stop, or stop and then continue.
				 */
				flag = 1;
				if (!unlikely(options & WCONTINUED))
					continue;
M
Matthew Wilcox 已提交
1526 1527 1528
				retval = wait_task_continued(p,
						(options & WNOWAIT), infop,
						stat_addr, ru);
L
Linus Torvalds 已提交
1529
			}
1530 1531
			if (retval != 0) /* tasklist_lock released */
				goto end;
L
Linus Torvalds 已提交
1532 1533
		}
		if (!flag) {
1534
			list_for_each_entry(p, &tsk->ptrace_children,
O
Oleg Nesterov 已提交
1535 1536 1537
								ptrace_list) {
				flag = eligible_child(pid, options, p);
				if (!flag)
L
Linus Torvalds 已提交
1538
					continue;
O
Oleg Nesterov 已提交
1539 1540 1541 1542
				if (likely(flag > 0))
					break;
				retval = flag;
				goto end;
L
Linus Torvalds 已提交
1543 1544 1545 1546 1547
			}
		}
		if (options & __WNOTHREAD)
			break;
		tsk = next_thread(tsk);
E
Eric Sesterhenn 已提交
1548
		BUG_ON(tsk->signal != current->signal);
L
Linus Torvalds 已提交
1549 1550
	} while (tsk != current);
	read_unlock(&tasklist_lock);
O
Oleg Nesterov 已提交
1551

L
Linus Torvalds 已提交
1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566
	if (flag) {
		if (options & WNOHANG)
			goto end;
		retval = -ERESTARTSYS;
		if (signal_pending(current))
			goto end;
		schedule();
		goto repeat;
	}
	retval = -ECHILD;
end:
	current->state = TASK_RUNNING;
	remove_wait_queue(&current->signal->wait_chldexit,&wait);
	if (infop) {
		if (retval > 0)
1567
			retval = 0;
L
Linus Torvalds 已提交
1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652
		else {
			/*
			 * For a WNOHANG return, clear out all the fields
			 * we would set so the user can easily tell the
			 * difference.
			 */
			if (!retval)
				retval = put_user(0, &infop->si_signo);
			if (!retval)
				retval = put_user(0, &infop->si_errno);
			if (!retval)
				retval = put_user(0, &infop->si_code);
			if (!retval)
				retval = put_user(0, &infop->si_pid);
			if (!retval)
				retval = put_user(0, &infop->si_uid);
			if (!retval)
				retval = put_user(0, &infop->si_status);
		}
	}
	return retval;
}

asmlinkage long sys_waitid(int which, pid_t pid,
			   struct siginfo __user *infop, int options,
			   struct rusage __user *ru)
{
	long ret;

	if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
		return -EINVAL;
	if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
		return -EINVAL;

	switch (which) {
	case P_ALL:
		pid = -1;
		break;
	case P_PID:
		if (pid <= 0)
			return -EINVAL;
		break;
	case P_PGID:
		if (pid <= 0)
			return -EINVAL;
		pid = -pid;
		break;
	default:
		return -EINVAL;
	}

	ret = do_wait(pid, options, infop, NULL, ru);

	/* avoid REGPARM breakage on x86: */
	prevent_tail_call(ret);
	return ret;
}

asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
			  int options, struct rusage __user *ru)
{
	long ret;

	if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
			__WNOTHREAD|__WCLONE|__WALL))
		return -EINVAL;
	ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);

	/* avoid REGPARM breakage on x86: */
	prevent_tail_call(ret);
	return ret;
}

#ifdef __ARCH_WANT_SYS_WAITPID

/*
 * sys_waitpid() remains for compatibility. waitpid() should be
 * implemented by calling sys_wait4() from libc.a.
 */
asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
{
	return sys_wait4(pid, stat_addr, options, NULL);
}

#endif