xref: /openbmc/linux/fs/proc/array.c (revision 034f90b3)
1 /*
2  *  linux/fs/proc/array.c
3  *
4  *  Copyright (C) 1992  by Linus Torvalds
5  *  based on ideas by Darren Senn
6  *
7  * Fixes:
8  * Michael. K. Johnson: stat,statm extensions.
9  *                      <johnsonm@stolaf.edu>
10  *
11  * Pauline Middelink :  Made cmdline,envline only break at '\0's, to
12  *                      make sure SET_PROCTITLE works. Also removed
13  *                      bad '!' which forced address recalculation for
14  *                      EVERY character on the current page.
15  *                      <middelin@polyware.iaf.nl>
16  *
17  * Danny ter Haar    :	added cpuinfo
18  *			<dth@cistron.nl>
19  *
20  * Alessandro Rubini :  profile extension.
21  *                      <rubini@ipvvis.unipv.it>
22  *
23  * Jeff Tranter      :  added BogoMips field to cpuinfo
24  *                      <Jeff_Tranter@Mitel.COM>
25  *
26  * Bruno Haible      :  remove 4K limit for the maps file
27  *			<haible@ma2s2.mathematik.uni-karlsruhe.de>
28  *
29  * Yves Arrouye      :  remove removal of trailing spaces in get_array.
30  *			<Yves.Arrouye@marin.fdn.fr>
31  *
32  * Jerome Forissier  :  added per-CPU time information to /proc/stat
33  *                      and /proc/<pid>/cpu extension
34  *                      <forissier@isia.cma.fr>
35  *			- Incorporation and non-SMP safe operation
36  *			of forissier patch in 2.1.78 by
37  *			Hans Marcus <crowbar@concepts.nl>
38  *
39  * aeb@cwi.nl        :  /proc/partitions
40  *
41  *
42  * Alan Cox	     :  security fixes.
43  *			<alan@lxorguk.ukuu.org.uk>
44  *
45  * Al Viro           :  safe handling of mm_struct
46  *
47  * Gerhard Wichert   :  added BIGMEM support
48  * Siemens AG           <Gerhard.Wichert@pdb.siemens.de>
49  *
50  * Al Viro & Jeff Garzik :  moved most of the thing into base.c and
51  *			 :  proc_misc.c. The rest may eventually go into
52  *			 :  base.c too.
53  */
54 
55 #include <linux/types.h>
56 #include <linux/errno.h>
57 #include <linux/time.h>
58 #include <linux/kernel.h>
59 #include <linux/kernel_stat.h>
60 #include <linux/tty.h>
61 #include <linux/string.h>
62 #include <linux/mman.h>
63 #include <linux/proc_fs.h>
64 #include <linux/ioport.h>
65 #include <linux/uaccess.h>
66 #include <linux/io.h>
67 #include <linux/mm.h>
68 #include <linux/hugetlb.h>
69 #include <linux/pagemap.h>
70 #include <linux/swap.h>
71 #include <linux/smp.h>
72 #include <linux/signal.h>
73 #include <linux/highmem.h>
74 #include <linux/file.h>
75 #include <linux/fdtable.h>
76 #include <linux/times.h>
77 #include <linux/cpuset.h>
78 #include <linux/rcupdate.h>
79 #include <linux/delayacct.h>
80 #include <linux/seq_file.h>
81 #include <linux/pid_namespace.h>
82 #include <linux/ptrace.h>
83 #include <linux/tracehook.h>
84 #include <linux/string_helpers.h>
85 #include <linux/user_namespace.h>
86 
87 #include <asm/pgtable.h>
88 #include <asm/processor.h>
89 #include "internal.h"
90 
91 static inline void task_name(struct seq_file *m, struct task_struct *p)
92 {
93 	char *buf;
94 	char tcomm[sizeof(p->comm)];
95 
96 	get_task_comm(tcomm, p);
97 
98 	seq_puts(m, "Name:\t");
99 	buf = m->buf + m->count;
100 
101 	/* Ignore error for now */
102 	string_escape_str(tcomm, &buf, m->size - m->count,
103 			  ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\");
104 
105 	m->count = buf - m->buf;
106 	seq_putc(m, '\n');
107 }
108 
109 /*
110  * The task state array is a strange "bitmap" of
111  * reasons to sleep. Thus "running" is zero, and
112  * you can test for combinations of others with
113  * simple bit tests.
114  */
115 static const char * const task_state_array[] = {
116 	"R (running)",		/*   0 */
117 	"S (sleeping)",		/*   1 */
118 	"D (disk sleep)",	/*   2 */
119 	"T (stopped)",		/*   4 */
120 	"t (tracing stop)",	/*   8 */
121 	"X (dead)",		/*  16 */
122 	"Z (zombie)",		/*  32 */
123 };
124 
125 static inline const char *get_task_state(struct task_struct *tsk)
126 {
127 	unsigned int state = (tsk->state | tsk->exit_state) & TASK_REPORT;
128 
129 	BUILD_BUG_ON(1 + ilog2(TASK_REPORT) != ARRAY_SIZE(task_state_array)-1);
130 
131 	return task_state_array[fls(state)];
132 }
133 
134 static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
135 				struct pid *pid, struct task_struct *p)
136 {
137 	struct user_namespace *user_ns = seq_user_ns(m);
138 	struct group_info *group_info;
139 	int g;
140 	struct task_struct *tracer;
141 	const struct cred *cred;
142 	pid_t ppid, tpid = 0, tgid, ngid;
143 	unsigned int max_fds = 0;
144 
145 	rcu_read_lock();
146 	ppid = pid_alive(p) ?
147 		task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
148 
149 	tracer = ptrace_parent(p);
150 	if (tracer)
151 		tpid = task_pid_nr_ns(tracer, ns);
152 
153 	tgid = task_tgid_nr_ns(p, ns);
154 	ngid = task_numa_group_id(p);
155 	cred = get_task_cred(p);
156 
157 	task_lock(p);
158 	if (p->files)
159 		max_fds = files_fdtable(p->files)->max_fds;
160 	task_unlock(p);
161 	rcu_read_unlock();
162 
163 	seq_printf(m,
164 		"State:\t%s\n"
165 		"Tgid:\t%d\n"
166 		"Ngid:\t%d\n"
167 		"Pid:\t%d\n"
168 		"PPid:\t%d\n"
169 		"TracerPid:\t%d\n"
170 		"Uid:\t%d\t%d\t%d\t%d\n"
171 		"Gid:\t%d\t%d\t%d\t%d\n"
172 		"FDSize:\t%d\nGroups:\t",
173 		get_task_state(p),
174 		tgid, ngid, pid_nr_ns(pid, ns), ppid, tpid,
175 		from_kuid_munged(user_ns, cred->uid),
176 		from_kuid_munged(user_ns, cred->euid),
177 		from_kuid_munged(user_ns, cred->suid),
178 		from_kuid_munged(user_ns, cred->fsuid),
179 		from_kgid_munged(user_ns, cred->gid),
180 		from_kgid_munged(user_ns, cred->egid),
181 		from_kgid_munged(user_ns, cred->sgid),
182 		from_kgid_munged(user_ns, cred->fsgid),
183 		max_fds);
184 
185 	group_info = cred->group_info;
186 	for (g = 0; g < group_info->ngroups; g++)
187 		seq_printf(m, "%d ",
188 			   from_kgid_munged(user_ns, GROUP_AT(group_info, g)));
189 	put_cred(cred);
190 
191 	seq_putc(m, '\n');
192 }
193 
194 void render_sigset_t(struct seq_file *m, const char *header,
195 				sigset_t *set)
196 {
197 	int i;
198 
199 	seq_puts(m, header);
200 
201 	i = _NSIG;
202 	do {
203 		int x = 0;
204 
205 		i -= 4;
206 		if (sigismember(set, i+1)) x |= 1;
207 		if (sigismember(set, i+2)) x |= 2;
208 		if (sigismember(set, i+3)) x |= 4;
209 		if (sigismember(set, i+4)) x |= 8;
210 		seq_printf(m, "%x", x);
211 	} while (i >= 4);
212 
213 	seq_putc(m, '\n');
214 }
215 
216 static void collect_sigign_sigcatch(struct task_struct *p, sigset_t *ign,
217 				    sigset_t *catch)
218 {
219 	struct k_sigaction *k;
220 	int i;
221 
222 	k = p->sighand->action;
223 	for (i = 1; i <= _NSIG; ++i, ++k) {
224 		if (k->sa.sa_handler == SIG_IGN)
225 			sigaddset(ign, i);
226 		else if (k->sa.sa_handler != SIG_DFL)
227 			sigaddset(catch, i);
228 	}
229 }
230 
231 static inline void task_sig(struct seq_file *m, struct task_struct *p)
232 {
233 	unsigned long flags;
234 	sigset_t pending, shpending, blocked, ignored, caught;
235 	int num_threads = 0;
236 	unsigned long qsize = 0;
237 	unsigned long qlim = 0;
238 
239 	sigemptyset(&pending);
240 	sigemptyset(&shpending);
241 	sigemptyset(&blocked);
242 	sigemptyset(&ignored);
243 	sigemptyset(&caught);
244 
245 	if (lock_task_sighand(p, &flags)) {
246 		pending = p->pending.signal;
247 		shpending = p->signal->shared_pending.signal;
248 		blocked = p->blocked;
249 		collect_sigign_sigcatch(p, &ignored, &caught);
250 		num_threads = get_nr_threads(p);
251 		rcu_read_lock();  /* FIXME: is this correct? */
252 		qsize = atomic_read(&__task_cred(p)->user->sigpending);
253 		rcu_read_unlock();
254 		qlim = task_rlimit(p, RLIMIT_SIGPENDING);
255 		unlock_task_sighand(p, &flags);
256 	}
257 
258 	seq_printf(m, "Threads:\t%d\n", num_threads);
259 	seq_printf(m, "SigQ:\t%lu/%lu\n", qsize, qlim);
260 
261 	/* render them all */
262 	render_sigset_t(m, "SigPnd:\t", &pending);
263 	render_sigset_t(m, "ShdPnd:\t", &shpending);
264 	render_sigset_t(m, "SigBlk:\t", &blocked);
265 	render_sigset_t(m, "SigIgn:\t", &ignored);
266 	render_sigset_t(m, "SigCgt:\t", &caught);
267 }
268 
269 static void render_cap_t(struct seq_file *m, const char *header,
270 			kernel_cap_t *a)
271 {
272 	unsigned __capi;
273 
274 	seq_puts(m, header);
275 	CAP_FOR_EACH_U32(__capi) {
276 		seq_printf(m, "%08x",
277 			   a->cap[CAP_LAST_U32 - __capi]);
278 	}
279 	seq_putc(m, '\n');
280 }
281 
282 static inline void task_cap(struct seq_file *m, struct task_struct *p)
283 {
284 	const struct cred *cred;
285 	kernel_cap_t cap_inheritable, cap_permitted, cap_effective, cap_bset;
286 
287 	rcu_read_lock();
288 	cred = __task_cred(p);
289 	cap_inheritable	= cred->cap_inheritable;
290 	cap_permitted	= cred->cap_permitted;
291 	cap_effective	= cred->cap_effective;
292 	cap_bset	= cred->cap_bset;
293 	rcu_read_unlock();
294 
295 	render_cap_t(m, "CapInh:\t", &cap_inheritable);
296 	render_cap_t(m, "CapPrm:\t", &cap_permitted);
297 	render_cap_t(m, "CapEff:\t", &cap_effective);
298 	render_cap_t(m, "CapBnd:\t", &cap_bset);
299 }
300 
301 static inline void task_seccomp(struct seq_file *m, struct task_struct *p)
302 {
303 #ifdef CONFIG_SECCOMP
304 	seq_printf(m, "Seccomp:\t%d\n", p->seccomp.mode);
305 #endif
306 }
307 
308 static inline void task_context_switch_counts(struct seq_file *m,
309 						struct task_struct *p)
310 {
311 	seq_printf(m,	"voluntary_ctxt_switches:\t%lu\n"
312 			"nonvoluntary_ctxt_switches:\t%lu\n",
313 			p->nvcsw,
314 			p->nivcsw);
315 }
316 
317 static void task_cpus_allowed(struct seq_file *m, struct task_struct *task)
318 {
319 	seq_printf(m, "Cpus_allowed:\t%*pb\n",
320 		   cpumask_pr_args(&task->cpus_allowed));
321 	seq_printf(m, "Cpus_allowed_list:\t%*pbl\n",
322 		   cpumask_pr_args(&task->cpus_allowed));
323 }
324 
325 int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
326 			struct pid *pid, struct task_struct *task)
327 {
328 	struct mm_struct *mm = get_task_mm(task);
329 
330 	task_name(m, task);
331 	task_state(m, ns, pid, task);
332 
333 	if (mm) {
334 		task_mem(m, mm);
335 		mmput(mm);
336 	}
337 	task_sig(m, task);
338 	task_cap(m, task);
339 	task_seccomp(m, task);
340 	task_cpus_allowed(m, task);
341 	cpuset_task_status_allowed(m, task);
342 	task_context_switch_counts(m, task);
343 	return 0;
344 }
345 
346 static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
347 			struct pid *pid, struct task_struct *task, int whole)
348 {
349 	unsigned long vsize, eip, esp, wchan = ~0UL;
350 	int priority, nice;
351 	int tty_pgrp = -1, tty_nr = 0;
352 	sigset_t sigign, sigcatch;
353 	char state;
354 	pid_t ppid = 0, pgid = -1, sid = -1;
355 	int num_threads = 0;
356 	int permitted;
357 	struct mm_struct *mm;
358 	unsigned long long start_time;
359 	unsigned long cmin_flt = 0, cmaj_flt = 0;
360 	unsigned long  min_flt = 0,  maj_flt = 0;
361 	cputime_t cutime, cstime, utime, stime;
362 	cputime_t cgtime, gtime;
363 	unsigned long rsslim = 0;
364 	char tcomm[sizeof(task->comm)];
365 	unsigned long flags;
366 
367 	state = *get_task_state(task);
368 	vsize = eip = esp = 0;
369 	permitted = ptrace_may_access(task, PTRACE_MODE_READ | PTRACE_MODE_NOAUDIT);
370 	mm = get_task_mm(task);
371 	if (mm) {
372 		vsize = task_vsize(mm);
373 		if (permitted) {
374 			eip = KSTK_EIP(task);
375 			esp = KSTK_ESP(task);
376 		}
377 	}
378 
379 	get_task_comm(tcomm, task);
380 
381 	sigemptyset(&sigign);
382 	sigemptyset(&sigcatch);
383 	cutime = cstime = utime = stime = 0;
384 	cgtime = gtime = 0;
385 
386 	if (lock_task_sighand(task, &flags)) {
387 		struct signal_struct *sig = task->signal;
388 
389 		if (sig->tty) {
390 			struct pid *pgrp = tty_get_pgrp(sig->tty);
391 			tty_pgrp = pid_nr_ns(pgrp, ns);
392 			put_pid(pgrp);
393 			tty_nr = new_encode_dev(tty_devnum(sig->tty));
394 		}
395 
396 		num_threads = get_nr_threads(task);
397 		collect_sigign_sigcatch(task, &sigign, &sigcatch);
398 
399 		cmin_flt = sig->cmin_flt;
400 		cmaj_flt = sig->cmaj_flt;
401 		cutime = sig->cutime;
402 		cstime = sig->cstime;
403 		cgtime = sig->cgtime;
404 		rsslim = ACCESS_ONCE(sig->rlim[RLIMIT_RSS].rlim_cur);
405 
406 		/* add up live thread stats at the group level */
407 		if (whole) {
408 			struct task_struct *t = task;
409 			do {
410 				min_flt += t->min_flt;
411 				maj_flt += t->maj_flt;
412 				gtime += task_gtime(t);
413 			} while_each_thread(task, t);
414 
415 			min_flt += sig->min_flt;
416 			maj_flt += sig->maj_flt;
417 			thread_group_cputime_adjusted(task, &utime, &stime);
418 			gtime += sig->gtime;
419 		}
420 
421 		sid = task_session_nr_ns(task, ns);
422 		ppid = task_tgid_nr_ns(task->real_parent, ns);
423 		pgid = task_pgrp_nr_ns(task, ns);
424 
425 		unlock_task_sighand(task, &flags);
426 	}
427 
428 	if (permitted && (!whole || num_threads < 2))
429 		wchan = get_wchan(task);
430 	if (!whole) {
431 		min_flt = task->min_flt;
432 		maj_flt = task->maj_flt;
433 		task_cputime_adjusted(task, &utime, &stime);
434 		gtime = task_gtime(task);
435 	}
436 
437 	/* scale priority and nice values from timeslices to -20..20 */
438 	/* to make it look like a "normal" Unix priority/nice value  */
439 	priority = task_prio(task);
440 	nice = task_nice(task);
441 
442 	/* convert nsec -> ticks */
443 	start_time = nsec_to_clock_t(task->real_start_time);
444 
445 	seq_printf(m, "%d (%s) %c", pid_nr_ns(pid, ns), tcomm, state);
446 	seq_put_decimal_ll(m, ' ', ppid);
447 	seq_put_decimal_ll(m, ' ', pgid);
448 	seq_put_decimal_ll(m, ' ', sid);
449 	seq_put_decimal_ll(m, ' ', tty_nr);
450 	seq_put_decimal_ll(m, ' ', tty_pgrp);
451 	seq_put_decimal_ull(m, ' ', task->flags);
452 	seq_put_decimal_ull(m, ' ', min_flt);
453 	seq_put_decimal_ull(m, ' ', cmin_flt);
454 	seq_put_decimal_ull(m, ' ', maj_flt);
455 	seq_put_decimal_ull(m, ' ', cmaj_flt);
456 	seq_put_decimal_ull(m, ' ', cputime_to_clock_t(utime));
457 	seq_put_decimal_ull(m, ' ', cputime_to_clock_t(stime));
458 	seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cutime));
459 	seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cstime));
460 	seq_put_decimal_ll(m, ' ', priority);
461 	seq_put_decimal_ll(m, ' ', nice);
462 	seq_put_decimal_ll(m, ' ', num_threads);
463 	seq_put_decimal_ull(m, ' ', 0);
464 	seq_put_decimal_ull(m, ' ', start_time);
465 	seq_put_decimal_ull(m, ' ', vsize);
466 	seq_put_decimal_ull(m, ' ', mm ? get_mm_rss(mm) : 0);
467 	seq_put_decimal_ull(m, ' ', rsslim);
468 	seq_put_decimal_ull(m, ' ', mm ? (permitted ? mm->start_code : 1) : 0);
469 	seq_put_decimal_ull(m, ' ', mm ? (permitted ? mm->end_code : 1) : 0);
470 	seq_put_decimal_ull(m, ' ', (permitted && mm) ? mm->start_stack : 0);
471 	seq_put_decimal_ull(m, ' ', esp);
472 	seq_put_decimal_ull(m, ' ', eip);
473 	/* The signal information here is obsolete.
474 	 * It must be decimal for Linux 2.0 compatibility.
475 	 * Use /proc/#/status for real-time signals.
476 	 */
477 	seq_put_decimal_ull(m, ' ', task->pending.signal.sig[0] & 0x7fffffffUL);
478 	seq_put_decimal_ull(m, ' ', task->blocked.sig[0] & 0x7fffffffUL);
479 	seq_put_decimal_ull(m, ' ', sigign.sig[0] & 0x7fffffffUL);
480 	seq_put_decimal_ull(m, ' ', sigcatch.sig[0] & 0x7fffffffUL);
481 	seq_put_decimal_ull(m, ' ', wchan);
482 	seq_put_decimal_ull(m, ' ', 0);
483 	seq_put_decimal_ull(m, ' ', 0);
484 	seq_put_decimal_ll(m, ' ', task->exit_signal);
485 	seq_put_decimal_ll(m, ' ', task_cpu(task));
486 	seq_put_decimal_ull(m, ' ', task->rt_priority);
487 	seq_put_decimal_ull(m, ' ', task->policy);
488 	seq_put_decimal_ull(m, ' ', delayacct_blkio_ticks(task));
489 	seq_put_decimal_ull(m, ' ', cputime_to_clock_t(gtime));
490 	seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cgtime));
491 
492 	if (mm && permitted) {
493 		seq_put_decimal_ull(m, ' ', mm->start_data);
494 		seq_put_decimal_ull(m, ' ', mm->end_data);
495 		seq_put_decimal_ull(m, ' ', mm->start_brk);
496 		seq_put_decimal_ull(m, ' ', mm->arg_start);
497 		seq_put_decimal_ull(m, ' ', mm->arg_end);
498 		seq_put_decimal_ull(m, ' ', mm->env_start);
499 		seq_put_decimal_ull(m, ' ', mm->env_end);
500 	} else
501 		seq_printf(m, " 0 0 0 0 0 0 0");
502 
503 	if (permitted)
504 		seq_put_decimal_ll(m, ' ', task->exit_code);
505 	else
506 		seq_put_decimal_ll(m, ' ', 0);
507 
508 	seq_putc(m, '\n');
509 	if (mm)
510 		mmput(mm);
511 	return 0;
512 }
513 
514 int proc_tid_stat(struct seq_file *m, struct pid_namespace *ns,
515 			struct pid *pid, struct task_struct *task)
516 {
517 	return do_task_stat(m, ns, pid, task, 0);
518 }
519 
520 int proc_tgid_stat(struct seq_file *m, struct pid_namespace *ns,
521 			struct pid *pid, struct task_struct *task)
522 {
523 	return do_task_stat(m, ns, pid, task, 1);
524 }
525 
526 int proc_pid_statm(struct seq_file *m, struct pid_namespace *ns,
527 			struct pid *pid, struct task_struct *task)
528 {
529 	unsigned long size = 0, resident = 0, shared = 0, text = 0, data = 0;
530 	struct mm_struct *mm = get_task_mm(task);
531 
532 	if (mm) {
533 		size = task_statm(mm, &shared, &text, &data, &resident);
534 		mmput(mm);
535 	}
536 	/*
537 	 * For quick read, open code by putting numbers directly
538 	 * expected format is
539 	 * seq_printf(m, "%lu %lu %lu %lu 0 %lu 0\n",
540 	 *               size, resident, shared, text, data);
541 	 */
542 	seq_put_decimal_ull(m, 0, size);
543 	seq_put_decimal_ull(m, ' ', resident);
544 	seq_put_decimal_ull(m, ' ', shared);
545 	seq_put_decimal_ull(m, ' ', text);
546 	seq_put_decimal_ull(m, ' ', 0);
547 	seq_put_decimal_ull(m, ' ', data);
548 	seq_put_decimal_ull(m, ' ', 0);
549 	seq_putc(m, '\n');
550 
551 	return 0;
552 }
553 
554 #ifdef CONFIG_CHECKPOINT_RESTORE
555 static struct pid *
556 get_children_pid(struct inode *inode, struct pid *pid_prev, loff_t pos)
557 {
558 	struct task_struct *start, *task;
559 	struct pid *pid = NULL;
560 
561 	read_lock(&tasklist_lock);
562 
563 	start = pid_task(proc_pid(inode), PIDTYPE_PID);
564 	if (!start)
565 		goto out;
566 
567 	/*
568 	 * Lets try to continue searching first, this gives
569 	 * us significant speedup on children-rich processes.
570 	 */
571 	if (pid_prev) {
572 		task = pid_task(pid_prev, PIDTYPE_PID);
573 		if (task && task->real_parent == start &&
574 		    !(list_empty(&task->sibling))) {
575 			if (list_is_last(&task->sibling, &start->children))
576 				goto out;
577 			task = list_first_entry(&task->sibling,
578 						struct task_struct, sibling);
579 			pid = get_pid(task_pid(task));
580 			goto out;
581 		}
582 	}
583 
584 	/*
585 	 * Slow search case.
586 	 *
587 	 * We might miss some children here if children
588 	 * are exited while we were not holding the lock,
589 	 * but it was never promised to be accurate that
590 	 * much.
591 	 *
592 	 * "Just suppose that the parent sleeps, but N children
593 	 *  exit after we printed their tids. Now the slow paths
594 	 *  skips N extra children, we miss N tasks." (c)
595 	 *
596 	 * So one need to stop or freeze the leader and all
597 	 * its children to get a precise result.
598 	 */
599 	list_for_each_entry(task, &start->children, sibling) {
600 		if (pos-- == 0) {
601 			pid = get_pid(task_pid(task));
602 			break;
603 		}
604 	}
605 
606 out:
607 	read_unlock(&tasklist_lock);
608 	return pid;
609 }
610 
611 static int children_seq_show(struct seq_file *seq, void *v)
612 {
613 	struct inode *inode = seq->private;
614 	pid_t pid;
615 
616 	pid = pid_nr_ns(v, inode->i_sb->s_fs_info);
617 	return seq_printf(seq, "%d ", pid);
618 }
619 
620 static void *children_seq_start(struct seq_file *seq, loff_t *pos)
621 {
622 	return get_children_pid(seq->private, NULL, *pos);
623 }
624 
625 static void *children_seq_next(struct seq_file *seq, void *v, loff_t *pos)
626 {
627 	struct pid *pid;
628 
629 	pid = get_children_pid(seq->private, v, *pos + 1);
630 	put_pid(v);
631 
632 	++*pos;
633 	return pid;
634 }
635 
636 static void children_seq_stop(struct seq_file *seq, void *v)
637 {
638 	put_pid(v);
639 }
640 
641 static const struct seq_operations children_seq_ops = {
642 	.start	= children_seq_start,
643 	.next	= children_seq_next,
644 	.stop	= children_seq_stop,
645 	.show	= children_seq_show,
646 };
647 
648 static int children_seq_open(struct inode *inode, struct file *file)
649 {
650 	struct seq_file *m;
651 	int ret;
652 
653 	ret = seq_open(file, &children_seq_ops);
654 	if (ret)
655 		return ret;
656 
657 	m = file->private_data;
658 	m->private = inode;
659 
660 	return ret;
661 }
662 
663 int children_seq_release(struct inode *inode, struct file *file)
664 {
665 	seq_release(inode, file);
666 	return 0;
667 }
668 
669 const struct file_operations proc_tid_children_operations = {
670 	.open    = children_seq_open,
671 	.read    = seq_read,
672 	.llseek  = seq_lseek,
673 	.release = children_seq_release,
674 };
675 #endif /* CONFIG_CHECKPOINT_RESTORE */
676