/*
   *  linux/fs/proc/array.c
   *
   *  Copyright (C) 1992  by Linus Torvalds
   *  based on ideas by Darren Senn
   *
   * Fixes:
   * Michael. K. Johnson: stat,statm extensions.
   *                      <johnsonm@stolaf.edu>
   *
   * Pauline Middelink :  Made cmdline,envline only break at '\0's, to
   *                      make sure SET_PROCTITLE works. Also removed
   *                      bad '!' which forced address recalculation for
   *                      EVERY character on the current page.
   *                      <middelin@polyware.iaf.nl>
   *
   * Danny ter Haar    :	added cpuinfo
   *			<dth@cistron.nl>
   *
   * Alessandro Rubini :  profile extension.
   *                      <rubini@ipvvis.unipv.it>
   *
   * Jeff Tranter      :  added BogoMips field to cpuinfo
   *                      <Jeff_Tranter@Mitel.COM>
   *
   * Bruno Haible      :  remove 4K limit for the maps file
   *			<haible@ma2s2.mathematik.uni-karlsruhe.de>
   *
   * Yves Arrouye      :  remove removal of trailing spaces in get_array.
   *			<Yves.Arrouye@marin.fdn.fr>
   *
   * Jerome Forissier  :  added per-CPU time information to /proc/stat
   *                      and /proc/<pid>/cpu extension
   *                      <forissier@isia.cma.fr>
   *			- Incorporation and non-SMP safe operation
   *			of forissier patch in 2.1.78 by
   *			Hans Marcus <crowbar@concepts.nl>
   *
   * aeb@cwi.nl        :  /proc/partitions
   *
   *
   * Alan Cox	     :  security fixes.
   *			<alan@lxorguk.ukuu.org.uk>
   *
   * Al Viro           :  safe handling of mm_struct
   *
   * Gerhard Wichert   :  added BIGMEM support
   * Siemens AG           <Gerhard.Wichert@pdb.siemens.de>
   *
   * Al Viro & Jeff Garzik :  moved most of the thing into base.c and
   *			 :  proc_misc.c. The rest may eventually go into
   *			 :  base.c too.
   */
  
  #include <linux/types.h>
  #include <linux/errno.h>
  #include <linux/time.h>
  #include <linux/kernel.h>
  #include <linux/kernel_stat.h>
  #include <linux/tty.h>
  #include <linux/string.h>
  #include <linux/mman.h>
  #include <linux/proc_fs.h>
  #include <linux/ioport.h>
  #include <linux/uaccess.h>
  #include <linux/io.h>
  #include <linux/mm.h>
  #include <linux/hugetlb.h>
  #include <linux/pagemap.h>
  #include <linux/swap.h>
  #include <linux/smp.h>
  #include <linux/signal.h>
  #include <linux/highmem.h>
  #include <linux/file.h>
  #include <linux/fdtable.h>
  #include <linux/times.h>
  #include <linux/cpuset.h>
  #include <linux/rcupdate.h>
  #include <linux/delayacct.h>
  #include <linux/seq_file.h>
  #include <linux/pid_namespace.h>
  #include <linux/ptrace.h>
  #include <linux/tracehook.h>
  #include <linux/user_namespace.h>
  
  #include <asm/pgtable.h>
  #include <asm/processor.h>
  #include "internal.h"
  
  static inline void task_name(struct seq_file *m, struct task_struct *p)
  {
  	int i;
  	char *buf, *end;
  	char *name;
  	char tcomm[sizeof(p->comm)];
  
  	get_task_comm(tcomm, p);
  
  	seq_puts(m, "Name:\t");
  	end = m->buf + m->size;
  	buf = m->buf + m->count;
  	name = tcomm;
  	i = sizeof(tcomm);
  	while (i && (buf < end)) {
  		unsigned char c = *name;
  		name++;
  		i--;
  		*buf = c;
  		if (!c)
  			break;
  		if (c == '\\') {
  			buf++;
  			if (buf < end)
  				*buf++ = c;
  			continue;
  		}
  		if (c == '
  ') {
  			*buf++ = '\\';
  			if (buf < end)
  				*buf++ = 'n';
  			continue;
  		}
  		buf++;
  	}
  	m->count = buf - m->buf;
  	seq_putc(m, '
  ');
  }
  
  /*
   * The task state array is a strange "bitmap" of
   * reasons to sleep. Thus "running" is zero, and
   * you can test for combinations of others with
   * simple bit tests.
   */
  static const char * const task_state_array[] = {
  	"R (running)",		/*   0 */
  	"S (sleeping)",		/*   1 */
  	"D (disk sleep)",	/*   2 */
  	"T (stopped)",		/*   4 */
  	"t (tracing stop)",	/*   8 */
  	"Z (zombie)",		/*  16 */
  	"X (dead)",		/*  32 */
  };
  
  static inline const char *get_task_state(struct task_struct *tsk)
  {
  	unsigned int state = (tsk->state | tsk->exit_state) & TASK_REPORT;
  
  	BUILD_BUG_ON(1 + ilog2(TASK_REPORT) != ARRAY_SIZE(task_state_array)-1);
  
  	return task_state_array[fls(state)];
  }
  
  static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
  				struct pid *pid, struct task_struct *p)
  {
  	struct user_namespace *user_ns = seq_user_ns(m);
  	struct group_info *group_info;
  	int g;
  	struct fdtable *fdt = NULL;
  	const struct cred *cred;
  	pid_t ppid, tpid;
  
  	rcu_read_lock();
  	ppid = pid_alive(p) ?
  		task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
  	tpid = 0;
  	if (pid_alive(p)) {
  		struct task_struct *tracer = ptrace_parent(p);
  		if (tracer)
  			tpid = task_pid_nr_ns(tracer, ns);
  	}
  	cred = get_task_cred(p);
  	seq_printf(m,
  		"State:\t%s
  "
  		"Tgid:\t%d
  "
  		"Ngid:\t%d
  "
  		"Pid:\t%d
  "
  		"PPid:\t%d
  "
  		"TracerPid:\t%d
  "
  		"Uid:\t%d\t%d\t%d\t%d
  "
  		"Gid:\t%d\t%d\t%d\t%d
  ",
  		get_task_state(p),
  		task_tgid_nr_ns(p, ns),
  		task_numa_group_id(p),
  		pid_nr_ns(pid, ns),
  		ppid, tpid,
  		from_kuid_munged(user_ns, cred->uid),
  		from_kuid_munged(user_ns, cred->euid),
  		from_kuid_munged(user_ns, cred->suid),
  		from_kuid_munged(user_ns, cred->fsuid),
  		from_kgid_munged(user_ns, cred->gid),
  		from_kgid_munged(user_ns, cred->egid),
  		from_kgid_munged(user_ns, cred->sgid),
  		from_kgid_munged(user_ns, cred->fsgid));
  
  	task_lock(p);
  	if (p->files)
  		fdt = files_fdtable(p->files);
  	seq_printf(m,
  		"FDSize:\t%d
  "
  		"Groups:\t",
  		fdt ? fdt->max_fds : 0);
  	rcu_read_unlock();
  
  	group_info = cred->group_info;
  	task_unlock(p);
  
  	for (g = 0; g < group_info->ngroups; g++)
  		seq_printf(m, "%d ",
  			   from_kgid_munged(user_ns, GROUP_AT(group_info, g)));
  	put_cred(cred);
  
  	seq_putc(m, '
  ');
  }
  
  void render_sigset_t(struct seq_file *m, const char *header,
  				sigset_t *set)
  {
  	int i;
  
  	seq_puts(m, header);
  
  	i = _NSIG;
  	do {
  		int x = 0;
  
  		i -= 4;
  		if (sigismember(set, i+1)) x |= 1;
  		if (sigismember(set, i+2)) x |= 2;
  		if (sigismember(set, i+3)) x |= 4;
  		if (sigismember(set, i+4)) x |= 8;
  		seq_printf(m, "%x", x);
  	} while (i >= 4);
  
  	seq_putc(m, '
  ');
  }
  
  static void collect_sigign_sigcatch(struct task_struct *p, sigset_t *ign,
  				    sigset_t *catch)
  {
  	struct k_sigaction *k;
  	int i;
  
  	k = p->sighand->action;
  	for (i = 1; i <= _NSIG; ++i, ++k) {
  		if (k->sa.sa_handler == SIG_IGN)
  			sigaddset(ign, i);
  		else if (k->sa.sa_handler != SIG_DFL)
  			sigaddset(catch, i);
  	}
  }
  
  static inline void task_sig(struct seq_file *m, struct task_struct *p)
  {
  	unsigned long flags;
  	sigset_t pending, shpending, blocked, ignored, caught;
  	int num_threads = 0;
  	unsigned long qsize = 0;
  	unsigned long qlim = 0;
  
  	sigemptyset(&pending);
  	sigemptyset(&shpending);
  	sigemptyset(&blocked);
  	sigemptyset(&ignored);
  	sigemptyset(&caught);
  
  	if (lock_task_sighand(p, &flags)) {
  		pending = p->pending.signal;
  		shpending = p->signal->shared_pending.signal;
  		blocked = p->blocked;
  		collect_sigign_sigcatch(p, &ignored, &caught);
  		num_threads = get_nr_threads(p);
  		rcu_read_lock();  /* FIXME: is this correct? */
  		qsize = atomic_read(&__task_cred(p)->user->sigpending);
  		rcu_read_unlock();
  		qlim = task_rlimit(p, RLIMIT_SIGPENDING);
  		unlock_task_sighand(p, &flags);
  	}
  
  	seq_printf(m, "Threads:\t%d
  ", num_threads);
  	seq_printf(m, "SigQ:\t%lu/%lu
  ", qsize, qlim);
  
  	/* render them all */
  	render_sigset_t(m, "SigPnd:\t", &pending);
  	render_sigset_t(m, "ShdPnd:\t", &shpending);
  	render_sigset_t(m, "SigBlk:\t", &blocked);
  	render_sigset_t(m, "SigIgn:\t", &ignored);
  	render_sigset_t(m, "SigCgt:\t", &caught);
  }
  
  static void render_cap_t(struct seq_file *m, const char *header,
  			kernel_cap_t *a)
  {
  	unsigned __capi;
  
  	seq_puts(m, header);
  	CAP_FOR_EACH_U32(__capi) {
  		seq_printf(m, "%08x",
  			   a->cap[CAP_LAST_U32 - __capi]);
  	}
  	seq_putc(m, '
  ');
  }
  
  static inline void task_cap(struct seq_file *m, struct task_struct *p)
  {
  	const struct cred *cred;
  	kernel_cap_t cap_inheritable, cap_permitted, cap_effective, cap_bset;
  
  	rcu_read_lock();
  	cred = __task_cred(p);
  	cap_inheritable	= cred->cap_inheritable;
  	cap_permitted	= cred->cap_permitted;
  	cap_effective	= cred->cap_effective;
  	cap_bset	= cred->cap_bset;
  	rcu_read_unlock();
  
  	render_cap_t(m, "CapInh:\t", &cap_inheritable);
  	render_cap_t(m, "CapPrm:\t", &cap_permitted);
  	render_cap_t(m, "CapEff:\t", &cap_effective);
  	render_cap_t(m, "CapBnd:\t", &cap_bset);
  }
  
  static inline void task_seccomp(struct seq_file *m, struct task_struct *p)
  {
  #ifdef CONFIG_SECCOMP
  	seq_printf(m, "Seccomp:\t%d
  ", p->seccomp.mode);
  #endif
  }
  
  static inline void task_context_switch_counts(struct seq_file *m,
  						struct task_struct *p)
  {
  	seq_printf(m,	"voluntary_ctxt_switches:\t%lu
  "
  			"nonvoluntary_ctxt_switches:\t%lu
  ",
  			p->nvcsw,
  			p->nivcsw);
  }
  
  static void task_cpus_allowed(struct seq_file *m, struct task_struct *task)
  {
  	seq_puts(m, "Cpus_allowed:\t");
  	seq_cpumask(m, &task->cpus_allowed);
  	seq_putc(m, '
  ');
  	seq_puts(m, "Cpus_allowed_list:\t");
  	seq_cpumask_list(m, &task->cpus_allowed);
  	seq_putc(m, '
  ');
  }
  
  int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
  			struct pid *pid, struct task_struct *task)
  {
  	struct mm_struct *mm = get_task_mm(task);
  
  	task_name(m, task);
  	task_state(m, ns, pid, task);
  
  	if (mm) {
  		task_mem(m, mm);
  		mmput(mm);
  	}
  	task_sig(m, task);
  	task_cap(m, task);
  	task_seccomp(m, task);
  	task_cpus_allowed(m, task);
  	cpuset_task_status_allowed(m, task);
  	task_context_switch_counts(m, task);
  	return 0;
  }
  
  static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
  			struct pid *pid, struct task_struct *task, int whole)
  {
  	unsigned long vsize, eip, esp, wchan = ~0UL;
  	int priority, nice;
  	int tty_pgrp = -1, tty_nr = 0;
  	sigset_t sigign, sigcatch;
  	char state;
  	pid_t ppid = 0, pgid = -1, sid = -1;
  	int num_threads = 0;
  	int permitted;
  	struct mm_struct *mm;
  	unsigned long long start_time;
  	unsigned long cmin_flt = 0, cmaj_flt = 0;
  	unsigned long  min_flt = 0,  maj_flt = 0;
  	cputime_t cutime, cstime, utime, stime;
  	cputime_t cgtime, gtime;
  	unsigned long rsslim = 0;
  	char tcomm[sizeof(task->comm)];
  	unsigned long flags;
  
  	state = *get_task_state(task);
  	vsize = eip = esp = 0;
  	permitted = ptrace_may_access(task, PTRACE_MODE_READ | PTRACE_MODE_NOAUDIT);
  	mm = get_task_mm(task);
  	if (mm) {
  		vsize = task_vsize(mm);
  		if (permitted) {
  			eip = KSTK_EIP(task);
  			esp = KSTK_ESP(task);
  		}
  	}
  
  	get_task_comm(tcomm, task);
  
  	sigemptyset(&sigign);
  	sigemptyset(&sigcatch);
  	cutime = cstime = utime = stime = 0;
  	cgtime = gtime = 0;
  
  	if (lock_task_sighand(task, &flags)) {
  		struct signal_struct *sig = task->signal;
  
  		if (sig->tty) {
  			struct pid *pgrp = tty_get_pgrp(sig->tty);
  			tty_pgrp = pid_nr_ns(pgrp, ns);
  			put_pid(pgrp);
  			tty_nr = new_encode_dev(tty_devnum(sig->tty));
  		}
  
  		num_threads = get_nr_threads(task);
  		collect_sigign_sigcatch(task, &sigign, &sigcatch);
  
  		cmin_flt = sig->cmin_flt;
  		cmaj_flt = sig->cmaj_flt;
  		cutime = sig->cutime;
  		cstime = sig->cstime;
  		cgtime = sig->cgtime;
  		rsslim = ACCESS_ONCE(sig->rlim[RLIMIT_RSS].rlim_cur);
  
  		/* add up live thread stats at the group level */
  		if (whole) {
  			struct task_struct *t = task;
  			do {
  				min_flt += t->min_flt;
  				maj_flt += t->maj_flt;
  				gtime += task_gtime(t);
  			} while_each_thread(task, t);
  
  			min_flt += sig->min_flt;
  			maj_flt += sig->maj_flt;
  			thread_group_cputime_adjusted(task, &utime, &stime);
  			gtime += sig->gtime;
  		}
  
  		sid = task_session_nr_ns(task, ns);
  		ppid = task_tgid_nr_ns(task->real_parent, ns);
  		pgid = task_pgrp_nr_ns(task, ns);
  
  		unlock_task_sighand(task, &flags);
  	}
  
  	if (permitted && (!whole || num_threads < 2))
  		wchan = get_wchan(task);
  	if (!whole) {
  		min_flt = task->min_flt;
  		maj_flt = task->maj_flt;
  		task_cputime_adjusted(task, &utime, &stime);
  		gtime = task_gtime(task);
  	}
  
  	/* scale priority and nice values from timeslices to -20..20 */
  	/* to make it look like a "normal" Unix priority/nice value  */
  	priority = task_prio(task);
  	nice = task_nice(task);
  
  	/* Temporary variable needed for gcc-2.96 */
  	/* convert timespec -> nsec*/
  	start_time =
  		(unsigned long long)task->real_start_time.tv_sec * NSEC_PER_SEC
  				+ task->real_start_time.tv_nsec;
  	/* convert nsec -> ticks */
  	start_time = nsec_to_clock_t(start_time);
  
  	seq_printf(m, "%d (%s) %c", pid_nr_ns(pid, ns), tcomm, state);
  	seq_put_decimal_ll(m, ' ', ppid);
  	seq_put_decimal_ll(m, ' ', pgid);
  	seq_put_decimal_ll(m, ' ', sid);
  	seq_put_decimal_ll(m, ' ', tty_nr);
  	seq_put_decimal_ll(m, ' ', tty_pgrp);
  	seq_put_decimal_ull(m, ' ', task->flags);
  	seq_put_decimal_ull(m, ' ', min_flt);
  	seq_put_decimal_ull(m, ' ', cmin_flt);
  	seq_put_decimal_ull(m, ' ', maj_flt);
  	seq_put_decimal_ull(m, ' ', cmaj_flt);
  	seq_put_decimal_ull(m, ' ', cputime_to_clock_t(utime));
  	seq_put_decimal_ull(m, ' ', cputime_to_clock_t(stime));
  	seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cutime));
  	seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cstime));
  	seq_put_decimal_ll(m, ' ', priority);
  	seq_put_decimal_ll(m, ' ', nice);
  	seq_put_decimal_ll(m, ' ', num_threads);
  	seq_put_decimal_ull(m, ' ', 0);
  	seq_put_decimal_ull(m, ' ', start_time);
  	seq_put_decimal_ull(m, ' ', vsize);
  	seq_put_decimal_ull(m, ' ', mm ? get_mm_rss(mm) : 0);
  	seq_put_decimal_ull(m, ' ', rsslim);
  	seq_put_decimal_ull(m, ' ', mm ? (permitted ? mm->start_code : 1) : 0);
  	seq_put_decimal_ull(m, ' ', mm ? (permitted ? mm->end_code : 1) : 0);
  	seq_put_decimal_ull(m, ' ', (permitted && mm) ? mm->start_stack : 0);
  	seq_put_decimal_ull(m, ' ', esp);
  	seq_put_decimal_ull(m, ' ', eip);
  	/* The signal information here is obsolete.
  	 * It must be decimal for Linux 2.0 compatibility.
  	 * Use /proc/#/status for real-time signals.
  	 */
  	seq_put_decimal_ull(m, ' ', task->pending.signal.sig[0] & 0x7fffffffUL);
  	seq_put_decimal_ull(m, ' ', task->blocked.sig[0] & 0x7fffffffUL);
  	seq_put_decimal_ull(m, ' ', sigign.sig[0] & 0x7fffffffUL);
  	seq_put_decimal_ull(m, ' ', sigcatch.sig[0] & 0x7fffffffUL);
  	seq_put_decimal_ull(m, ' ', wchan);
  	seq_put_decimal_ull(m, ' ', 0);
  	seq_put_decimal_ull(m, ' ', 0);
  	seq_put_decimal_ll(m, ' ', task->exit_signal);
  	seq_put_decimal_ll(m, ' ', task_cpu(task));
  	seq_put_decimal_ull(m, ' ', task->rt_priority);
  	seq_put_decimal_ull(m, ' ', task->policy);
  	seq_put_decimal_ull(m, ' ', delayacct_blkio_ticks(task));
  	seq_put_decimal_ull(m, ' ', cputime_to_clock_t(gtime));
  	seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cgtime));
  
  	if (mm && permitted) {
  		seq_put_decimal_ull(m, ' ', mm->start_data);
  		seq_put_decimal_ull(m, ' ', mm->end_data);
  		seq_put_decimal_ull(m, ' ', mm->start_brk);
  		seq_put_decimal_ull(m, ' ', mm->arg_start);
  		seq_put_decimal_ull(m, ' ', mm->arg_end);
  		seq_put_decimal_ull(m, ' ', mm->env_start);
  		seq_put_decimal_ull(m, ' ', mm->env_end);
  	} else
  		seq_printf(m, " 0 0 0 0 0 0 0");
  
  	if (permitted)
  		seq_put_decimal_ll(m, ' ', task->exit_code);
  	else
  		seq_put_decimal_ll(m, ' ', 0);
  
  	seq_putc(m, '
  ');
  	if (mm)
  		mmput(mm);
  	return 0;
  }
  
  int proc_tid_stat(struct seq_file *m, struct pid_namespace *ns,
  			struct pid *pid, struct task_struct *task)
  {
  	return do_task_stat(m, ns, pid, task, 0);
  }
  
  int proc_tgid_stat(struct seq_file *m, struct pid_namespace *ns,
  			struct pid *pid, struct task_struct *task)
  {
  	return do_task_stat(m, ns, pid, task, 1);
  }
  
  int proc_pid_statm(struct seq_file *m, struct pid_namespace *ns,
  			struct pid *pid, struct task_struct *task)
  {
  	unsigned long size = 0, resident = 0, shared = 0, text = 0, data = 0;
  	struct mm_struct *mm = get_task_mm(task);
  
  	if (mm) {
  		size = task_statm(mm, &shared, &text, &data, &resident);
  		mmput(mm);
  	}
  	/*
  	 * For quick read, open code by putting numbers directly
  	 * expected format is
  	 * seq_printf(m, "%lu %lu %lu %lu 0 %lu 0
  ",
  	 *               size, resident, shared, text, data);
  	 */
  	seq_put_decimal_ull(m, 0, size);
  	seq_put_decimal_ull(m, ' ', resident);
  	seq_put_decimal_ull(m, ' ', shared);
  	seq_put_decimal_ull(m, ' ', text);
  	seq_put_decimal_ull(m, ' ', 0);
  	seq_put_decimal_ull(m, ' ', data);
  	seq_put_decimal_ull(m, ' ', 0);
  	seq_putc(m, '
  ');
  
  	return 0;
  }
  
  #ifdef CONFIG_CHECKPOINT_RESTORE
  static struct pid *
  get_children_pid(struct inode *inode, struct pid *pid_prev, loff_t pos)
  {
  	struct task_struct *start, *task;
  	struct pid *pid = NULL;
  
  	read_lock(&tasklist_lock);
  
  	start = pid_task(proc_pid(inode), PIDTYPE_PID);
  	if (!start)
  		goto out;
  
  	/*
  	 * Lets try to continue searching first, this gives
  	 * us significant speedup on children-rich processes.
  	 */
  	if (pid_prev) {
  		task = pid_task(pid_prev, PIDTYPE_PID);
  		if (task && task->real_parent == start &&
  		    !(list_empty(&task->sibling))) {
  			if (list_is_last(&task->sibling, &start->children))
  				goto out;
  			task = list_first_entry(&task->sibling,
  						struct task_struct, sibling);
  			pid = get_pid(task_pid(task));
  			goto out;
  		}
  	}
  
  	/*
  	 * Slow search case.
  	 *
  	 * We might miss some children here if children
  	 * are exited while we were not holding the lock,
  	 * but it was never promised to be accurate that
  	 * much.
  	 *
  	 * "Just suppose that the parent sleeps, but N children
  	 *  exit after we printed their tids. Now the slow paths
  	 *  skips N extra children, we miss N tasks." (c)
  	 *
  	 * So one need to stop or freeze the leader and all
  	 * its children to get a precise result.
  	 */
  	list_for_each_entry(task, &start->children, sibling) {
  		if (pos-- == 0) {
  			pid = get_pid(task_pid(task));
  			break;
  		}
  	}
  
  out:
  	read_unlock(&tasklist_lock);
  	return pid;
  }
  
  static int children_seq_show(struct seq_file *seq, void *v)
  {
  	struct inode *inode = seq->private;
  	pid_t pid;
  
  	pid = pid_nr_ns(v, inode->i_sb->s_fs_info);
  	return seq_printf(seq, "%d ", pid);
  }
  
  static void *children_seq_start(struct seq_file *seq, loff_t *pos)
  {
  	return get_children_pid(seq->private, NULL, *pos);
  }
  
  static void *children_seq_next(struct seq_file *seq, void *v, loff_t *pos)
  {
  	struct pid *pid;
  
  	pid = get_children_pid(seq->private, v, *pos + 1);
  	put_pid(v);
  
  	++*pos;
  	return pid;
  }
  
  static void children_seq_stop(struct seq_file *seq, void *v)
  {
  	put_pid(v);
  }
  
  static const struct seq_operations children_seq_ops = {
  	.start	= children_seq_start,
  	.next	= children_seq_next,
  	.stop	= children_seq_stop,
  	.show	= children_seq_show,
  };
  
  static int children_seq_open(struct inode *inode, struct file *file)
  {
  	struct seq_file *m;
  	int ret;
  
  	ret = seq_open(file, &children_seq_ops);
  	if (ret)
  		return ret;
  
  	m = file->private_data;
  	m->private = inode;
  
  	return ret;
  }
  
  int children_seq_release(struct inode *inode, struct file *file)
  {
  	seq_release(inode, file);
  	return 0;
  }
  
  const struct file_operations proc_tid_children_operations = {
  	.open    = children_seq_open,
  	.read    = seq_read,
  	.llseek  = seq_lseek,
  	.release = children_seq_release,
  };
  #endif /* CONFIG_CHECKPOINT_RESTORE */