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linux_old1/fs/proc/array.c

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// SPDX-License-Identifier: GPL-2.0
/*
* 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/sched/mm.h>
#include <linux/sched/numa_balancing.h>
#include <linux/sched/task_stack.h>
#include <linux/sched/task.h>
#include <linux/sched/cputime.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/prctl.h>
#include <linux/ptrace.h>
#include <linux/tracehook.h>
#include <linux/string_helpers.h>
#include <linux/user_namespace.h>
#include <linux/fs_struct.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include "internal.h"
void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape)
{
char *buf;
size_t size;
char tcomm[64];
int ret;
if (p->flags & PF_WQ_WORKER)
wq_worker_comm(tcomm, sizeof(tcomm), p);
else
__get_task_comm(tcomm, sizeof(tcomm), p);
size = seq_get_buf(m, &buf);
if (escape) {
ret = string_escape_str(tcomm, buf, size,
ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\");
if (ret >= size)
ret = -1;
} else {
ret = strscpy(buf, tcomm, size);
}
seq_commit(m, ret);
}
/*
* 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[] = {
/* states in TASK_REPORT: */
"R (running)", /* 0x00 */
"S (sleeping)", /* 0x01 */
"D (disk sleep)", /* 0x02 */
"T (stopped)", /* 0x04 */
"t (tracing stop)", /* 0x08 */
"X (dead)", /* 0x10 */
"Z (zombie)", /* 0x20 */
"P (parked)", /* 0x40 */
/* states beyond TASK_REPORT: */
"I (idle)", /* 0x80 */
};
static inline const char *get_task_state(struct task_struct *tsk)
{
BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_array));
return task_state_array[task_state_index(tsk)];
}
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, umask = -1;
struct task_struct *tracer;
const struct cred *cred;
pid_t ppid, tpid = 0, tgid, ngid;
unsigned int max_fds = 0;
rcu_read_lock();
ppid = pid_alive(p) ?
task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
tracer = ptrace_parent(p);
if (tracer)
tpid = task_pid_nr_ns(tracer, ns);
tgid = task_tgid_nr_ns(p, ns);
ngid = task_numa_group_id(p);
cred = get_task_cred(p);
task_lock(p);
if (p->fs)
umask = p->fs->umask;
if (p->files)
max_fds = files_fdtable(p->files)->max_fds;
task_unlock(p);
rcu_read_unlock();
if (umask >= 0)
seq_printf(m, "Umask:\t%#04o\n", umask);
seq_puts(m, "State:\t");
seq_puts(m, get_task_state(p));
seq_put_decimal_ull(m, "\nTgid:\t", tgid);
seq_put_decimal_ull(m, "\nNgid:\t", ngid);
seq_put_decimal_ull(m, "\nPid:\t", pid_nr_ns(pid, ns));
seq_put_decimal_ull(m, "\nPPid:\t", ppid);
seq_put_decimal_ull(m, "\nTracerPid:\t", tpid);
seq_put_decimal_ull(m, "\nUid:\t", from_kuid_munged(user_ns, cred->uid));
seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->euid));
seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->suid));
seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->fsuid));
seq_put_decimal_ull(m, "\nGid:\t", from_kgid_munged(user_ns, cred->gid));
seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->egid));
seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->sgid));
seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->fsgid));
seq_put_decimal_ull(m, "\nFDSize:\t", max_fds);
seq_puts(m, "\nGroups:\t");
group_info = cred->group_info;
for (g = 0; g < group_info->ngroups; g++)
seq_put_decimal_ull(m, g ? " " : "",
from_kgid_munged(user_ns, group_info->gid[g]));
put_cred(cred);
/* Trailing space shouldn't have been added in the first place. */
seq_putc(m, ' ');
#ifdef CONFIG_PID_NS
seq_puts(m, "\nNStgid:");
for (g = ns->level; g <= pid->level; g++)
seq_put_decimal_ull(m, "\t", task_tgid_nr_ns(p, pid->numbers[g].ns));
seq_puts(m, "\nNSpid:");
for (g = ns->level; g <= pid->level; g++)
seq_put_decimal_ull(m, "\t", task_pid_nr_ns(p, pid->numbers[g].ns));
seq_puts(m, "\nNSpgid:");
for (g = ns->level; g <= pid->level; g++)
seq_put_decimal_ull(m, "\t", task_pgrp_nr_ns(p, pid->numbers[g].ns));
seq_puts(m, "\nNSsid:");
for (g = ns->level; g <= pid->level; g++)
seq_put_decimal_ull(m, "\t", task_session_nr_ns(p, pid->numbers[g].ns));
#endif
seq_putc(m, '\n');
}
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_putc(m, hex_asc[x]);
} while (i >= 4);
seq_putc(m, '\n');
}
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 int 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_put_decimal_ull(m, "Threads:\t", num_threads);
seq_put_decimal_ull(m, "\nSigQ:\t", qsize);
seq_put_decimal_ull(m, "/", qlim);
/* render them all */
render_sigset_t(m, "\nSigPnd:\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_put_hex_ll(m, NULL,
a->cap[CAP_LAST_U32 - __capi], 8);
}
seq_putc(m, '\n');
}
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, cap_ambient;
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;
cap_ambient = cred->cap_ambient;
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);
render_cap_t(m, "CapAmb:\t", &cap_ambient);
}
static inline void task_seccomp(struct seq_file *m, struct task_struct *p)
{
seq_put_decimal_ull(m, "NoNewPrivs:\t", task_no_new_privs(p));
#ifdef CONFIG_SECCOMP
seq_put_decimal_ull(m, "\nSeccomp:\t", p->seccomp.mode);
#endif
seq_puts(m, "\nSpeculation_Store_Bypass:\t");
switch (arch_prctl_spec_ctrl_get(p, PR_SPEC_STORE_BYPASS)) {
case -EINVAL:
seq_puts(m, "unknown");
break;
case PR_SPEC_NOT_AFFECTED:
seq_puts(m, "not vulnerable");
break;
case PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE:
seq_puts(m, "thread force mitigated");
break;
case PR_SPEC_PRCTL | PR_SPEC_DISABLE:
seq_puts(m, "thread mitigated");
break;
case PR_SPEC_PRCTL | PR_SPEC_ENABLE:
seq_puts(m, "thread vulnerable");
break;
case PR_SPEC_DISABLE:
seq_puts(m, "globally mitigated");
break;
default:
seq_puts(m, "vulnerable");
break;
}
seq_putc(m, '\n');
}
static inline void task_context_switch_counts(struct seq_file *m,
struct task_struct *p)
{
seq_put_decimal_ull(m, "voluntary_ctxt_switches:\t", p->nvcsw);
seq_put_decimal_ull(m, "\nnonvoluntary_ctxt_switches:\t", p->nivcsw);
seq_putc(m, '\n');
}
static void task_cpus_allowed(struct seq_file *m, struct task_struct *task)
{
seq_printf(m, "Cpus_allowed:\t%*pb\n",
cpumask_pr_args(task->cpus_ptr));
seq_printf(m, "Cpus_allowed_list:\t%*pbl\n",
cpumask_pr_args(task->cpus_ptr));
}
static inline void task_core_dumping(struct seq_file *m, struct mm_struct *mm)
{
seq_put_decimal_ull(m, "CoreDumping:\t", !!mm->core_state);
seq_putc(m, '\n');
}
static inline void task_thp_status(struct seq_file *m, struct mm_struct *mm)
{
bool thp_enabled = IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE);
if (thp_enabled)
thp_enabled = !test_bit(MMF_DISABLE_THP, &mm->flags);
seq_printf(m, "THP_enabled:\t%d\n", thp_enabled);
}
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);
seq_puts(m, "Name:\t");
proc_task_name(m, task, true);
seq_putc(m, '\n');
task_state(m, ns, pid, task);
if (mm) {
task_mem(m, mm);
task_core_dumping(m, mm);
task_thp_status(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 = 0;
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;
u64 cutime, cstime, utime, stime;
u64 cgtime, gtime;
unsigned long rsslim = 0;
unsigned long flags;
state = *get_task_state(task);
vsize = eip = esp = 0;
permitted = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS | PTRACE_MODE_NOAUDIT);
mm = get_task_mm(task);
if (mm) {
vsize = task_vsize(mm);
/*
* esp and eip are intentionally zeroed out. There is no
* non-racy way to read them without freezing the task.
* Programs that need reliable values can use ptrace(2).
*
* The only exception is if the task is core dumping because
* a program is not able to use ptrace(2) in that case. It is
* safe because the task has stopped executing permanently.
*/
if (permitted && (task->flags & (PF_EXITING|PF_DUMPCORE))) {
if (try_get_task_stack(task)) {
eip = KSTK_EIP(task);
esp = KSTK_ESP(task);
put_task_stack(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 = READ_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);
/* convert nsec -> ticks */
start_time = nsec_to_clock_t(task->real_start_time);
seq_put_decimal_ull(m, "", pid_nr_ns(pid, ns));
seq_puts(m, " (");
proc_task_name(m, task, false);
seq_puts(m, ") ");
seq_putc(m, 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, " ", nsec_to_clock_t(utime));
seq_put_decimal_ull(m, " ", nsec_to_clock_t(stime));
seq_put_decimal_ll(m, " ", nsec_to_clock_t(cutime));
seq_put_decimal_ll(m, " ", nsec_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);
/*
* We used to output the absolute kernel address, but that's an
* information leak - so instead we show a 0/1 flag here, to signal
* to user-space whether there's a wchan field in /proc/PID/wchan.
*
* This works with older implementations of procps as well.
*/
if (wchan)
seq_puts(m, " 1");
else
seq_puts(m, " 0");
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, " ", nsec_to_clock_t(gtime));
seq_put_decimal_ll(m, " ", nsec_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_puts(m, " 0 0 0 0 0 0 0");
if (permitted)
seq_put_decimal_ll(m, " ", task->exit_code);
else
seq_puts(m, " 0");
seq_putc(m, '\n');
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\n",
* size, resident, shared, text, data);
*/
seq_put_decimal_ull(m, "", 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, '\n');
return 0;
}
#ifdef CONFIG_PROC_CHILDREN
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 = file_inode(seq->file);
seq_printf(seq, "%d ", pid_nr_ns(v, proc_pid_ns(inode)));
return 0;
}
static void *children_seq_start(struct seq_file *seq, loff_t *pos)
{
return get_children_pid(file_inode(seq->file), NULL, *pos);
}
static void *children_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
struct pid *pid;
pid = get_children_pid(file_inode(seq->file), 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)
{
return seq_open(file, &children_seq_ops);
}
const struct file_operations proc_tid_children_operations = {
.open = children_seq_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
#endif /* CONFIG_PROC_CHILDREN */
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