1 // SPDX-License-Identifier: GPL-2.0
3 * linux/fs/proc/array.c
5 * Copyright (C) 1992 by Linus Torvalds
6 * based on ideas by Darren Senn
9 * Michael. K. Johnson: stat,statm extensions.
12 * Pauline Middelink : Made cmdline,envline only break at '\0's, to
13 * make sure SET_PROCTITLE works. Also removed
14 * bad '!' which forced address recalculation for
15 * EVERY character on the current page.
18 * Danny ter Haar : added cpuinfo
21 * Alessandro Rubini : profile extension.
24 * Jeff Tranter : added BogoMips field to cpuinfo
27 * Bruno Haible : remove 4K limit for the maps file
30 * Yves Arrouye : remove removal of trailing spaces in get_array.
33 * Jerome Forissier : added per-CPU time information to /proc/stat
34 * and /proc/<pid>/cpu extension
36 * - Incorporation and non-SMP safe operation
37 * of forissier patch in 2.1.78 by
43 * Alan Cox : security fixes.
46 * Al Viro : safe handling of mm_struct
48 * Gerhard Wichert : added BIGMEM support
51 * Al Viro & Jeff Garzik : moved most of the thing into base.c and
52 * : proc_misc.c. The rest may eventually go into
56 #include <linux/types.h>
57 #include <linux/errno.h>
58 #include <linux/time.h>
59 #include <linux/time_namespace.h>
60 #include <linux/kernel.h>
61 #include <linux/kernel_stat.h>
62 #include <linux/tty.h>
63 #include <linux/string.h>
64 #include <linux/mman.h>
65 #include <linux/sched/mm.h>
66 #include <linux/sched/numa_balancing.h>
67 #include <linux/sched/task_stack.h>
68 #include <linux/sched/task.h>
69 #include <linux/sched/cputime.h>
70 #include <linux/proc_fs.h>
71 #include <linux/ioport.h>
74 #include <linux/hugetlb.h>
75 #include <linux/pagemap.h>
76 #include <linux/swap.h>
77 #include <linux/smp.h>
78 #include <linux/signal.h>
79 #include <linux/highmem.h>
80 #include <linux/file.h>
81 #include <linux/fdtable.h>
82 #include <linux/times.h>
83 #include <linux/cpuset.h>
84 #include <linux/rcupdate.h>
85 #include <linux/delayacct.h>
86 #include <linux/seq_file.h>
87 #include <linux/pid_namespace.h>
88 #include <linux/prctl.h>
89 #include <linux/ptrace.h>
90 #include <linux/string_helpers.h>
91 #include <linux/user_namespace.h>
92 #include <linux/fs_struct.h>
93 #include <linux/kthread.h>
95 #include <asm/processor.h>
98 void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape)
103 * Test before PF_KTHREAD because all workqueue worker threads are
106 if (p->flags & PF_WQ_WORKER)
107 wq_worker_comm(tcomm, sizeof(tcomm), p);
108 else if (p->flags & PF_KTHREAD)
109 get_kthread_comm(tcomm, sizeof(tcomm), p);
111 __get_task_comm(tcomm, sizeof(tcomm), p);
114 seq_escape_str(m, tcomm, ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\");
116 seq_printf(m, "%.64s", tcomm);
120 * The task state array is a strange "bitmap" of
121 * reasons to sleep. Thus "running" is zero, and
122 * you can test for combinations of others with
125 static const char * const task_state_array[] = {
127 /* states in TASK_REPORT: */
128 "R (running)", /* 0x00 */
129 "S (sleeping)", /* 0x01 */
130 "D (disk sleep)", /* 0x02 */
131 "T (stopped)", /* 0x04 */
132 "t (tracing stop)", /* 0x08 */
133 "X (dead)", /* 0x10 */
134 "Z (zombie)", /* 0x20 */
135 "P (parked)", /* 0x40 */
137 /* states beyond TASK_REPORT: */
138 "I (idle)", /* 0x80 */
141 static inline const char *get_task_state(struct task_struct *tsk)
143 BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_array));
144 return task_state_array[task_state_index(tsk)];
147 static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
148 struct pid *pid, struct task_struct *p)
150 struct user_namespace *user_ns = seq_user_ns(m);
151 struct group_info *group_info;
153 struct task_struct *tracer;
154 const struct cred *cred;
155 pid_t ppid, tpid = 0, tgid, ngid;
156 unsigned int max_fds = 0;
159 ppid = pid_alive(p) ?
160 task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
162 tracer = ptrace_parent(p);
164 tpid = task_pid_nr_ns(tracer, ns);
166 tgid = task_tgid_nr_ns(p, ns);
167 ngid = task_numa_group_id(p);
168 cred = get_task_cred(p);
172 umask = p->fs->umask;
174 max_fds = files_fdtable(p->files)->max_fds;
179 seq_printf(m, "Umask:\t%#04o\n", umask);
180 seq_puts(m, "State:\t");
181 seq_puts(m, get_task_state(p));
183 seq_put_decimal_ull(m, "\nTgid:\t", tgid);
184 seq_put_decimal_ull(m, "\nNgid:\t", ngid);
185 seq_put_decimal_ull(m, "\nPid:\t", pid_nr_ns(pid, ns));
186 seq_put_decimal_ull(m, "\nPPid:\t", ppid);
187 seq_put_decimal_ull(m, "\nTracerPid:\t", tpid);
188 seq_put_decimal_ull(m, "\nUid:\t", from_kuid_munged(user_ns, cred->uid));
189 seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->euid));
190 seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->suid));
191 seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->fsuid));
192 seq_put_decimal_ull(m, "\nGid:\t", from_kgid_munged(user_ns, cred->gid));
193 seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->egid));
194 seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->sgid));
195 seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->fsgid));
196 seq_put_decimal_ull(m, "\nFDSize:\t", max_fds);
198 seq_puts(m, "\nGroups:\t");
199 group_info = cred->group_info;
200 for (g = 0; g < group_info->ngroups; g++)
201 seq_put_decimal_ull(m, g ? " " : "",
202 from_kgid_munged(user_ns, group_info->gid[g]));
204 /* Trailing space shouldn't have been added in the first place. */
208 seq_puts(m, "\nNStgid:");
209 for (g = ns->level; g <= pid->level; g++)
210 seq_put_decimal_ull(m, "\t", task_tgid_nr_ns(p, pid->numbers[g].ns));
211 seq_puts(m, "\nNSpid:");
212 for (g = ns->level; g <= pid->level; g++)
213 seq_put_decimal_ull(m, "\t", task_pid_nr_ns(p, pid->numbers[g].ns));
214 seq_puts(m, "\nNSpgid:");
215 for (g = ns->level; g <= pid->level; g++)
216 seq_put_decimal_ull(m, "\t", task_pgrp_nr_ns(p, pid->numbers[g].ns));
217 seq_puts(m, "\nNSsid:");
218 for (g = ns->level; g <= pid->level; g++)
219 seq_put_decimal_ull(m, "\t", task_session_nr_ns(p, pid->numbers[g].ns));
224 void render_sigset_t(struct seq_file *m, const char *header,
236 if (sigismember(set, i+1)) x |= 1;
237 if (sigismember(set, i+2)) x |= 2;
238 if (sigismember(set, i+3)) x |= 4;
239 if (sigismember(set, i+4)) x |= 8;
240 seq_putc(m, hex_asc[x]);
246 static void collect_sigign_sigcatch(struct task_struct *p, sigset_t *sigign,
249 struct k_sigaction *k;
252 k = p->sighand->action;
253 for (i = 1; i <= _NSIG; ++i, ++k) {
254 if (k->sa.sa_handler == SIG_IGN)
255 sigaddset(sigign, i);
256 else if (k->sa.sa_handler != SIG_DFL)
257 sigaddset(sigcatch, i);
261 static inline void task_sig(struct seq_file *m, struct task_struct *p)
264 sigset_t pending, shpending, blocked, ignored, caught;
266 unsigned int qsize = 0;
267 unsigned long qlim = 0;
269 sigemptyset(&pending);
270 sigemptyset(&shpending);
271 sigemptyset(&blocked);
272 sigemptyset(&ignored);
273 sigemptyset(&caught);
275 if (lock_task_sighand(p, &flags)) {
276 pending = p->pending.signal;
277 shpending = p->signal->shared_pending.signal;
278 blocked = p->blocked;
279 collect_sigign_sigcatch(p, &ignored, &caught);
280 num_threads = get_nr_threads(p);
281 rcu_read_lock(); /* FIXME: is this correct? */
282 qsize = get_rlimit_value(task_ucounts(p), UCOUNT_RLIMIT_SIGPENDING);
284 qlim = task_rlimit(p, RLIMIT_SIGPENDING);
285 unlock_task_sighand(p, &flags);
288 seq_put_decimal_ull(m, "Threads:\t", num_threads);
289 seq_put_decimal_ull(m, "\nSigQ:\t", qsize);
290 seq_put_decimal_ull(m, "/", qlim);
292 /* render them all */
293 render_sigset_t(m, "\nSigPnd:\t", &pending);
294 render_sigset_t(m, "ShdPnd:\t", &shpending);
295 render_sigset_t(m, "SigBlk:\t", &blocked);
296 render_sigset_t(m, "SigIgn:\t", &ignored);
297 render_sigset_t(m, "SigCgt:\t", &caught);
300 static void render_cap_t(struct seq_file *m, const char *header,
304 seq_put_hex_ll(m, NULL, a->val, 16);
308 static inline void task_cap(struct seq_file *m, struct task_struct *p)
310 const struct cred *cred;
311 kernel_cap_t cap_inheritable, cap_permitted, cap_effective,
312 cap_bset, cap_ambient;
315 cred = __task_cred(p);
316 cap_inheritable = cred->cap_inheritable;
317 cap_permitted = cred->cap_permitted;
318 cap_effective = cred->cap_effective;
319 cap_bset = cred->cap_bset;
320 cap_ambient = cred->cap_ambient;
323 render_cap_t(m, "CapInh:\t", &cap_inheritable);
324 render_cap_t(m, "CapPrm:\t", &cap_permitted);
325 render_cap_t(m, "CapEff:\t", &cap_effective);
326 render_cap_t(m, "CapBnd:\t", &cap_bset);
327 render_cap_t(m, "CapAmb:\t", &cap_ambient);
330 static inline void task_seccomp(struct seq_file *m, struct task_struct *p)
332 seq_put_decimal_ull(m, "NoNewPrivs:\t", task_no_new_privs(p));
333 #ifdef CONFIG_SECCOMP
334 seq_put_decimal_ull(m, "\nSeccomp:\t", p->seccomp.mode);
335 #ifdef CONFIG_SECCOMP_FILTER
336 seq_put_decimal_ull(m, "\nSeccomp_filters:\t",
337 atomic_read(&p->seccomp.filter_count));
340 seq_puts(m, "\nSpeculation_Store_Bypass:\t");
341 switch (arch_prctl_spec_ctrl_get(p, PR_SPEC_STORE_BYPASS)) {
343 seq_puts(m, "unknown");
345 case PR_SPEC_NOT_AFFECTED:
346 seq_puts(m, "not vulnerable");
348 case PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE:
349 seq_puts(m, "thread force mitigated");
351 case PR_SPEC_PRCTL | PR_SPEC_DISABLE:
352 seq_puts(m, "thread mitigated");
354 case PR_SPEC_PRCTL | PR_SPEC_ENABLE:
355 seq_puts(m, "thread vulnerable");
357 case PR_SPEC_DISABLE:
358 seq_puts(m, "globally mitigated");
361 seq_puts(m, "vulnerable");
365 seq_puts(m, "\nSpeculationIndirectBranch:\t");
366 switch (arch_prctl_spec_ctrl_get(p, PR_SPEC_INDIRECT_BRANCH)) {
368 seq_puts(m, "unsupported");
370 case PR_SPEC_NOT_AFFECTED:
371 seq_puts(m, "not affected");
373 case PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE:
374 seq_puts(m, "conditional force disabled");
376 case PR_SPEC_PRCTL | PR_SPEC_DISABLE:
377 seq_puts(m, "conditional disabled");
379 case PR_SPEC_PRCTL | PR_SPEC_ENABLE:
380 seq_puts(m, "conditional enabled");
383 seq_puts(m, "always enabled");
385 case PR_SPEC_DISABLE:
386 seq_puts(m, "always disabled");
389 seq_puts(m, "unknown");
395 static inline void task_context_switch_counts(struct seq_file *m,
396 struct task_struct *p)
398 seq_put_decimal_ull(m, "voluntary_ctxt_switches:\t", p->nvcsw);
399 seq_put_decimal_ull(m, "\nnonvoluntary_ctxt_switches:\t", p->nivcsw);
403 static void task_cpus_allowed(struct seq_file *m, struct task_struct *task)
405 seq_printf(m, "Cpus_allowed:\t%*pb\n",
406 cpumask_pr_args(&task->cpus_mask));
407 seq_printf(m, "Cpus_allowed_list:\t%*pbl\n",
408 cpumask_pr_args(&task->cpus_mask));
411 static inline void task_core_dumping(struct seq_file *m, struct task_struct *task)
413 seq_put_decimal_ull(m, "CoreDumping:\t", !!task->signal->core_state);
417 static inline void task_thp_status(struct seq_file *m, struct mm_struct *mm)
419 bool thp_enabled = IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE);
422 thp_enabled = !test_bit(MMF_DISABLE_THP, &mm->flags);
423 seq_printf(m, "THP_enabled:\t%d\n", thp_enabled);
426 int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
427 struct pid *pid, struct task_struct *task)
429 struct mm_struct *mm = get_task_mm(task);
431 seq_puts(m, "Name:\t");
432 proc_task_name(m, task, true);
435 task_state(m, ns, pid, task);
439 task_core_dumping(m, task);
440 task_thp_status(m, mm);
445 task_seccomp(m, task);
446 task_cpus_allowed(m, task);
447 cpuset_task_status_allowed(m, task);
448 task_context_switch_counts(m, task);
452 static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
453 struct pid *pid, struct task_struct *task, int whole)
455 unsigned long vsize, eip, esp, wchan = 0;
457 int tty_pgrp = -1, tty_nr = 0;
458 sigset_t sigign, sigcatch;
460 pid_t ppid = 0, pgid = -1, sid = -1;
463 struct mm_struct *mm;
464 unsigned long long start_time;
465 unsigned long cmin_flt = 0, cmaj_flt = 0;
466 unsigned long min_flt = 0, maj_flt = 0;
467 u64 cutime, cstime, utime, stime;
469 unsigned long rsslim = 0;
471 int exit_code = task->exit_code;
473 state = *get_task_state(task);
474 vsize = eip = esp = 0;
475 permitted = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS | PTRACE_MODE_NOAUDIT);
476 mm = get_task_mm(task);
478 vsize = task_vsize(mm);
480 * esp and eip are intentionally zeroed out. There is no
481 * non-racy way to read them without freezing the task.
482 * Programs that need reliable values can use ptrace(2).
484 * The only exception is if the task is core dumping because
485 * a program is not able to use ptrace(2) in that case. It is
486 * safe because the task has stopped executing permanently.
488 if (permitted && (task->flags & (PF_EXITING|PF_DUMPCORE))) {
489 if (try_get_task_stack(task)) {
490 eip = KSTK_EIP(task);
491 esp = KSTK_ESP(task);
492 put_task_stack(task);
497 sigemptyset(&sigign);
498 sigemptyset(&sigcatch);
499 cutime = cstime = utime = stime = 0;
502 if (lock_task_sighand(task, &flags)) {
503 struct signal_struct *sig = task->signal;
506 struct pid *pgrp = tty_get_pgrp(sig->tty);
507 tty_pgrp = pid_nr_ns(pgrp, ns);
509 tty_nr = new_encode_dev(tty_devnum(sig->tty));
512 num_threads = get_nr_threads(task);
513 collect_sigign_sigcatch(task, &sigign, &sigcatch);
515 cmin_flt = sig->cmin_flt;
516 cmaj_flt = sig->cmaj_flt;
517 cutime = sig->cutime;
518 cstime = sig->cstime;
519 cgtime = sig->cgtime;
520 rsslim = READ_ONCE(sig->rlim[RLIMIT_RSS].rlim_cur);
522 /* add up live thread stats at the group level */
524 struct task_struct *t = task;
526 min_flt += t->min_flt;
527 maj_flt += t->maj_flt;
528 gtime += task_gtime(t);
529 } while_each_thread(task, t);
531 min_flt += sig->min_flt;
532 maj_flt += sig->maj_flt;
533 thread_group_cputime_adjusted(task, &utime, &stime);
536 if (sig->flags & (SIGNAL_GROUP_EXIT | SIGNAL_STOP_STOPPED))
537 exit_code = sig->group_exit_code;
540 sid = task_session_nr_ns(task, ns);
541 ppid = task_tgid_nr_ns(task->real_parent, ns);
542 pgid = task_pgrp_nr_ns(task, ns);
544 unlock_task_sighand(task, &flags);
547 if (permitted && (!whole || num_threads < 2))
548 wchan = !task_is_running(task);
550 min_flt = task->min_flt;
551 maj_flt = task->maj_flt;
552 task_cputime_adjusted(task, &utime, &stime);
553 gtime = task_gtime(task);
556 /* scale priority and nice values from timeslices to -20..20 */
557 /* to make it look like a "normal" Unix priority/nice value */
558 priority = task_prio(task);
559 nice = task_nice(task);
561 /* apply timens offset for boottime and convert nsec -> ticks */
563 nsec_to_clock_t(timens_add_boottime_ns(task->start_boottime));
565 seq_put_decimal_ull(m, "", pid_nr_ns(pid, ns));
567 proc_task_name(m, task, false);
570 seq_put_decimal_ll(m, " ", ppid);
571 seq_put_decimal_ll(m, " ", pgid);
572 seq_put_decimal_ll(m, " ", sid);
573 seq_put_decimal_ll(m, " ", tty_nr);
574 seq_put_decimal_ll(m, " ", tty_pgrp);
575 seq_put_decimal_ull(m, " ", task->flags);
576 seq_put_decimal_ull(m, " ", min_flt);
577 seq_put_decimal_ull(m, " ", cmin_flt);
578 seq_put_decimal_ull(m, " ", maj_flt);
579 seq_put_decimal_ull(m, " ", cmaj_flt);
580 seq_put_decimal_ull(m, " ", nsec_to_clock_t(utime));
581 seq_put_decimal_ull(m, " ", nsec_to_clock_t(stime));
582 seq_put_decimal_ll(m, " ", nsec_to_clock_t(cutime));
583 seq_put_decimal_ll(m, " ", nsec_to_clock_t(cstime));
584 seq_put_decimal_ll(m, " ", priority);
585 seq_put_decimal_ll(m, " ", nice);
586 seq_put_decimal_ll(m, " ", num_threads);
587 seq_put_decimal_ull(m, " ", 0);
588 seq_put_decimal_ull(m, " ", start_time);
589 seq_put_decimal_ull(m, " ", vsize);
590 seq_put_decimal_ull(m, " ", mm ? get_mm_rss(mm) : 0);
591 seq_put_decimal_ull(m, " ", rsslim);
592 seq_put_decimal_ull(m, " ", mm ? (permitted ? mm->start_code : 1) : 0);
593 seq_put_decimal_ull(m, " ", mm ? (permitted ? mm->end_code : 1) : 0);
594 seq_put_decimal_ull(m, " ", (permitted && mm) ? mm->start_stack : 0);
595 seq_put_decimal_ull(m, " ", esp);
596 seq_put_decimal_ull(m, " ", eip);
597 /* The signal information here is obsolete.
598 * It must be decimal for Linux 2.0 compatibility.
599 * Use /proc/#/status for real-time signals.
601 seq_put_decimal_ull(m, " ", task->pending.signal.sig[0] & 0x7fffffffUL);
602 seq_put_decimal_ull(m, " ", task->blocked.sig[0] & 0x7fffffffUL);
603 seq_put_decimal_ull(m, " ", sigign.sig[0] & 0x7fffffffUL);
604 seq_put_decimal_ull(m, " ", sigcatch.sig[0] & 0x7fffffffUL);
607 * We used to output the absolute kernel address, but that's an
608 * information leak - so instead we show a 0/1 flag here, to signal
609 * to user-space whether there's a wchan field in /proc/PID/wchan.
611 * This works with older implementations of procps as well.
613 seq_put_decimal_ull(m, " ", wchan);
615 seq_put_decimal_ull(m, " ", 0);
616 seq_put_decimal_ull(m, " ", 0);
617 seq_put_decimal_ll(m, " ", task->exit_signal);
618 seq_put_decimal_ll(m, " ", task_cpu(task));
619 seq_put_decimal_ull(m, " ", task->rt_priority);
620 seq_put_decimal_ull(m, " ", task->policy);
621 seq_put_decimal_ull(m, " ", delayacct_blkio_ticks(task));
622 seq_put_decimal_ull(m, " ", nsec_to_clock_t(gtime));
623 seq_put_decimal_ll(m, " ", nsec_to_clock_t(cgtime));
625 if (mm && permitted) {
626 seq_put_decimal_ull(m, " ", mm->start_data);
627 seq_put_decimal_ull(m, " ", mm->end_data);
628 seq_put_decimal_ull(m, " ", mm->start_brk);
629 seq_put_decimal_ull(m, " ", mm->arg_start);
630 seq_put_decimal_ull(m, " ", mm->arg_end);
631 seq_put_decimal_ull(m, " ", mm->env_start);
632 seq_put_decimal_ull(m, " ", mm->env_end);
634 seq_puts(m, " 0 0 0 0 0 0 0");
637 seq_put_decimal_ll(m, " ", exit_code);
647 int proc_tid_stat(struct seq_file *m, struct pid_namespace *ns,
648 struct pid *pid, struct task_struct *task)
650 return do_task_stat(m, ns, pid, task, 0);
653 int proc_tgid_stat(struct seq_file *m, struct pid_namespace *ns,
654 struct pid *pid, struct task_struct *task)
656 return do_task_stat(m, ns, pid, task, 1);
659 int proc_pid_statm(struct seq_file *m, struct pid_namespace *ns,
660 struct pid *pid, struct task_struct *task)
662 struct mm_struct *mm = get_task_mm(task);
666 unsigned long resident = 0;
667 unsigned long shared = 0;
668 unsigned long text = 0;
669 unsigned long data = 0;
671 size = task_statm(mm, &shared, &text, &data, &resident);
675 * For quick read, open code by putting numbers directly
677 * seq_printf(m, "%lu %lu %lu %lu 0 %lu 0\n",
678 * size, resident, shared, text, data);
680 seq_put_decimal_ull(m, "", size);
681 seq_put_decimal_ull(m, " ", resident);
682 seq_put_decimal_ull(m, " ", shared);
683 seq_put_decimal_ull(m, " ", text);
684 seq_put_decimal_ull(m, " ", 0);
685 seq_put_decimal_ull(m, " ", data);
686 seq_put_decimal_ull(m, " ", 0);
689 seq_write(m, "0 0 0 0 0 0 0\n", 14);
694 #ifdef CONFIG_PROC_CHILDREN
696 get_children_pid(struct inode *inode, struct pid *pid_prev, loff_t pos)
698 struct task_struct *start, *task;
699 struct pid *pid = NULL;
701 read_lock(&tasklist_lock);
703 start = pid_task(proc_pid(inode), PIDTYPE_PID);
708 * Lets try to continue searching first, this gives
709 * us significant speedup on children-rich processes.
712 task = pid_task(pid_prev, PIDTYPE_PID);
713 if (task && task->real_parent == start &&
714 !(list_empty(&task->sibling))) {
715 if (list_is_last(&task->sibling, &start->children))
717 task = list_first_entry(&task->sibling,
718 struct task_struct, sibling);
719 pid = get_pid(task_pid(task));
727 * We might miss some children here if children
728 * are exited while we were not holding the lock,
729 * but it was never promised to be accurate that
732 * "Just suppose that the parent sleeps, but N children
733 * exit after we printed their tids. Now the slow paths
734 * skips N extra children, we miss N tasks." (c)
736 * So one need to stop or freeze the leader and all
737 * its children to get a precise result.
739 list_for_each_entry(task, &start->children, sibling) {
741 pid = get_pid(task_pid(task));
747 read_unlock(&tasklist_lock);
751 static int children_seq_show(struct seq_file *seq, void *v)
753 struct inode *inode = file_inode(seq->file);
755 seq_printf(seq, "%d ", pid_nr_ns(v, proc_pid_ns(inode->i_sb)));
759 static void *children_seq_start(struct seq_file *seq, loff_t *pos)
761 return get_children_pid(file_inode(seq->file), NULL, *pos);
764 static void *children_seq_next(struct seq_file *seq, void *v, loff_t *pos)
768 pid = get_children_pid(file_inode(seq->file), v, *pos + 1);
775 static void children_seq_stop(struct seq_file *seq, void *v)
780 static const struct seq_operations children_seq_ops = {
781 .start = children_seq_start,
782 .next = children_seq_next,
783 .stop = children_seq_stop,
784 .show = children_seq_show,
787 static int children_seq_open(struct inode *inode, struct file *file)
789 return seq_open(file, &children_seq_ops);
792 const struct file_operations proc_tid_children_operations = {
793 .open = children_seq_open,
796 .release = seq_release,
798 #endif /* CONFIG_PROC_CHILDREN */