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Linux 4.8.3
[linux/fpc-iii.git] / fs / proc / array.c
blob88c7de12197bd763c452b7770fcd19d15dcb3df1
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 #include <linux/fs_struct.h>
87
88 #include <asm/pgtable.h>
89 #include <asm/processor.h>
90 #include "internal.h"
91
92 static inline void task_name(struct seq_file *m, struct task_struct *p)
93 {
94 char *buf;
95 size_t size;
96 char tcomm[sizeof(p->comm)];
97 int ret;
98
99 get_task_comm(tcomm, p);
100
101 seq_puts(m, "Name:\t");
102
103 size = seq_get_buf(m, &buf);
104 ret = string_escape_str(tcomm, buf, size, ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\");
105 seq_commit(m, ret < size ? ret : -1);
106
107 seq_putc(m, '\n');
108 }
109
110 /*
111 * The task state array is a strange "bitmap" of
112 * reasons to sleep. Thus "running" is zero, and
113 * you can test for combinations of others with
114 * simple bit tests.
115 */
116 static const char * const task_state_array[] = {
117 "R (running)", /* 0 */
118 "S (sleeping)", /* 1 */
119 "D (disk sleep)", /* 2 */
120 "T (stopped)", /* 4 */
121 "t (tracing stop)", /* 8 */
122 "X (dead)", /* 16 */
123 "Z (zombie)", /* 32 */
124 };
125
126 static inline const char *get_task_state(struct task_struct *tsk)
127 {
128 unsigned int state = (tsk->state | tsk->exit_state) & TASK_REPORT;
129
130 /*
131 * Parked tasks do not run; they sit in __kthread_parkme().
132 * Without this check, we would report them as running, which is
133 * clearly wrong, so we report them as sleeping instead.
134 */
135 if (tsk->state == TASK_PARKED)
136 state = TASK_INTERRUPTIBLE;
137
138 BUILD_BUG_ON(1 + ilog2(TASK_REPORT) != ARRAY_SIZE(task_state_array)-1);
139
140 return task_state_array[fls(state)];
141 }
142
143 static inline int get_task_umask(struct task_struct *tsk)
144 {
145 struct fs_struct *fs;
146 int umask = -ENOENT;
147
148 task_lock(tsk);
149 fs = tsk->fs;
150 if (fs)
151 umask = fs->umask;
152 task_unlock(tsk);
153 return umask;
154 }
155
156 static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
157 struct pid *pid, struct task_struct *p)
158 {
159 struct user_namespace *user_ns = seq_user_ns(m);
160 struct group_info *group_info;
161 int g, umask;
162 struct task_struct *tracer;
163 const struct cred *cred;
164 pid_t ppid, tpid = 0, tgid, ngid;
165 unsigned int max_fds = 0;
166
167 rcu_read_lock();
168 ppid = pid_alive(p) ?
169 task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
170
171 tracer = ptrace_parent(p);
172 if (tracer)
173 tpid = task_pid_nr_ns(tracer, ns);
174
175 tgid = task_tgid_nr_ns(p, ns);
176 ngid = task_numa_group_id(p);
177 cred = get_task_cred(p);
178
179 umask = get_task_umask(p);
180 if (umask >= 0)
181 seq_printf(m, "Umask:\t%#04o\n", umask);
182
183 task_lock(p);
184 if (p->files)
185 max_fds = files_fdtable(p->files)->max_fds;
186 task_unlock(p);
187 rcu_read_unlock();
188
189 seq_printf(m,
190 "State:\t%s\n"
191 "Tgid:\t%d\n"
192 "Ngid:\t%d\n"
193 "Pid:\t%d\n"
194 "PPid:\t%d\n"
195 "TracerPid:\t%d\n"
196 "Uid:\t%d\t%d\t%d\t%d\n"
197 "Gid:\t%d\t%d\t%d\t%d\n"
198 "FDSize:\t%d\nGroups:\t",
199 get_task_state(p),
200 tgid, ngid, pid_nr_ns(pid, ns), ppid, tpid,
201 from_kuid_munged(user_ns, cred->uid),
202 from_kuid_munged(user_ns, cred->euid),
203 from_kuid_munged(user_ns, cred->suid),
204 from_kuid_munged(user_ns, cred->fsuid),
205 from_kgid_munged(user_ns, cred->gid),
206 from_kgid_munged(user_ns, cred->egid),
207 from_kgid_munged(user_ns, cred->sgid),
208 from_kgid_munged(user_ns, cred->fsgid),
209 max_fds);
210
211 group_info = cred->group_info;
212 for (g = 0; g < group_info->ngroups; g++)
213 seq_printf(m, "%d ",
214 from_kgid_munged(user_ns, GROUP_AT(group_info, g)));
215 put_cred(cred);
216
217 #ifdef CONFIG_PID_NS
218 seq_puts(m, "\nNStgid:");
219 for (g = ns->level; g <= pid->level; g++)
220 seq_printf(m, "\t%d",
221 task_tgid_nr_ns(p, pid->numbers[g].ns));
222 seq_puts(m, "\nNSpid:");
223 for (g = ns->level; g <= pid->level; g++)
224 seq_printf(m, "\t%d",
225 task_pid_nr_ns(p, pid->numbers[g].ns));
226 seq_puts(m, "\nNSpgid:");
227 for (g = ns->level; g <= pid->level; g++)
228 seq_printf(m, "\t%d",
229 task_pgrp_nr_ns(p, pid->numbers[g].ns));
230 seq_puts(m, "\nNSsid:");
231 for (g = ns->level; g <= pid->level; g++)
232 seq_printf(m, "\t%d",
233 task_session_nr_ns(p, pid->numbers[g].ns));
234 #endif
235 seq_putc(m, '\n');
236 }
237
238 void render_sigset_t(struct seq_file *m, const char *header,
239 sigset_t *set)
240 {
241 int i;
242
243 seq_puts(m, header);
244
245 i = _NSIG;
246 do {
247 int x = 0;
248
249 i -= 4;
250 if (sigismember(set, i+1)) x |= 1;
251 if (sigismember(set, i+2)) x |= 2;
252 if (sigismember(set, i+3)) x |= 4;
253 if (sigismember(set, i+4)) x |= 8;
254 seq_printf(m, "%x", x);
255 } while (i >= 4);
256
257 seq_putc(m, '\n');
258 }
259
260 static void collect_sigign_sigcatch(struct task_struct *p, sigset_t *ign,
261 sigset_t *catch)
262 {
263 struct k_sigaction *k;
264 int i;
265
266 k = p->sighand->action;
267 for (i = 1; i <= _NSIG; ++i, ++k) {
268 if (k->sa.sa_handler == SIG_IGN)
269 sigaddset(ign, i);
270 else if (k->sa.sa_handler != SIG_DFL)
271 sigaddset(catch, i);
272 }
273 }
274
275 static inline void task_sig(struct seq_file *m, struct task_struct *p)
276 {
277 unsigned long flags;
278 sigset_t pending, shpending, blocked, ignored, caught;
279 int num_threads = 0;
280 unsigned long qsize = 0;
281 unsigned long qlim = 0;
282
283 sigemptyset(&pending);
284 sigemptyset(&shpending);
285 sigemptyset(&blocked);
286 sigemptyset(&ignored);
287 sigemptyset(&caught);
288
289 if (lock_task_sighand(p, &flags)) {
290 pending = p->pending.signal;
291 shpending = p->signal->shared_pending.signal;
292 blocked = p->blocked;
293 collect_sigign_sigcatch(p, &ignored, &caught);
294 num_threads = get_nr_threads(p);
295 rcu_read_lock(); /* FIXME: is this correct? */
296 qsize = atomic_read(&__task_cred(p)->user->sigpending);
297 rcu_read_unlock();
298 qlim = task_rlimit(p, RLIMIT_SIGPENDING);
299 unlock_task_sighand(p, &flags);
300 }
301
302 seq_printf(m, "Threads:\t%d\n", num_threads);
303 seq_printf(m, "SigQ:\t%lu/%lu\n", qsize, qlim);
304
305 /* render them all */
306 render_sigset_t(m, "SigPnd:\t", &pending);
307 render_sigset_t(m, "ShdPnd:\t", &shpending);
308 render_sigset_t(m, "SigBlk:\t", &blocked);
309 render_sigset_t(m, "SigIgn:\t", &ignored);
310 render_sigset_t(m, "SigCgt:\t", &caught);
311 }
312
313 static void render_cap_t(struct seq_file *m, const char *header,
314 kernel_cap_t *a)
315 {
316 unsigned __capi;
317
318 seq_puts(m, header);
319 CAP_FOR_EACH_U32(__capi) {
320 seq_printf(m, "%08x",
321 a->cap[CAP_LAST_U32 - __capi]);
322 }
323 seq_putc(m, '\n');
324 }
325
326 static inline void task_cap(struct seq_file *m, struct task_struct *p)
327 {
328 const struct cred *cred;
329 kernel_cap_t cap_inheritable, cap_permitted, cap_effective,
330 cap_bset, cap_ambient;
331
332 rcu_read_lock();
333 cred = __task_cred(p);
334 cap_inheritable = cred->cap_inheritable;
335 cap_permitted = cred->cap_permitted;
336 cap_effective = cred->cap_effective;
337 cap_bset = cred->cap_bset;
338 cap_ambient = cred->cap_ambient;
339 rcu_read_unlock();
340
341 render_cap_t(m, "CapInh:\t", &cap_inheritable);
342 render_cap_t(m, "CapPrm:\t", &cap_permitted);
343 render_cap_t(m, "CapEff:\t", &cap_effective);
344 render_cap_t(m, "CapBnd:\t", &cap_bset);
345 render_cap_t(m, "CapAmb:\t", &cap_ambient);
346 }
347
348 static inline void task_seccomp(struct seq_file *m, struct task_struct *p)
349 {
350 #ifdef CONFIG_SECCOMP
351 seq_printf(m, "Seccomp:\t%d\n", p->seccomp.mode);
352 #endif
353 }
354
355 static inline void task_context_switch_counts(struct seq_file *m,
356 struct task_struct *p)
357 {
358 seq_printf(m, "voluntary_ctxt_switches:\t%lu\n"
359 "nonvoluntary_ctxt_switches:\t%lu\n",
360 p->nvcsw,
361 p->nivcsw);
362 }
363
364 static void task_cpus_allowed(struct seq_file *m, struct task_struct *task)
365 {
366 seq_printf(m, "Cpus_allowed:\t%*pb\n",
367 cpumask_pr_args(&task->cpus_allowed));
368 seq_printf(m, "Cpus_allowed_list:\t%*pbl\n",
369 cpumask_pr_args(&task->cpus_allowed));
370 }
371
372 int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
373 struct pid *pid, struct task_struct *task)
374 {
375 struct mm_struct *mm = get_task_mm(task);
376
377 task_name(m, task);
378 task_state(m, ns, pid, task);
379
380 if (mm) {
381 task_mem(m, mm);
382 mmput(mm);
383 }
384 task_sig(m, task);
385 task_cap(m, task);
386 task_seccomp(m, task);
387 task_cpus_allowed(m, task);
388 cpuset_task_status_allowed(m, task);
389 task_context_switch_counts(m, task);
390 return 0;
391 }
392
393 static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
394 struct pid *pid, struct task_struct *task, int whole)
395 {
396 unsigned long vsize, eip, esp, wchan = 0;
397 int priority, nice;
398 int tty_pgrp = -1, tty_nr = 0;
399 sigset_t sigign, sigcatch;
400 char state;
401 pid_t ppid = 0, pgid = -1, sid = -1;
402 int num_threads = 0;
403 int permitted;
404 struct mm_struct *mm;
405 unsigned long long start_time;
406 unsigned long cmin_flt = 0, cmaj_flt = 0;
407 unsigned long min_flt = 0, maj_flt = 0;
408 cputime_t cutime, cstime, utime, stime;
409 cputime_t cgtime, gtime;
410 unsigned long rsslim = 0;
411 char tcomm[sizeof(task->comm)];
412 unsigned long flags;
413
414 state = *get_task_state(task);
415 vsize = eip = esp = 0;
416 permitted = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS | PTRACE_MODE_NOAUDIT);
417 mm = get_task_mm(task);
418 if (mm) {
419 vsize = task_vsize(mm);
420 if (permitted) {
421 eip = KSTK_EIP(task);
422 esp = KSTK_ESP(task);
423 }
424 }
425
426 get_task_comm(tcomm, task);
427
428 sigemptyset(&sigign);
429 sigemptyset(&sigcatch);
430 cutime = cstime = utime = stime = 0;
431 cgtime = gtime = 0;
432
433 if (lock_task_sighand(task, &flags)) {
434 struct signal_struct *sig = task->signal;
435
436 if (sig->tty) {
437 struct pid *pgrp = tty_get_pgrp(sig->tty);
438 tty_pgrp = pid_nr_ns(pgrp, ns);
439 put_pid(pgrp);
440 tty_nr = new_encode_dev(tty_devnum(sig->tty));
441 }
442
443 num_threads = get_nr_threads(task);
444 collect_sigign_sigcatch(task, &sigign, &sigcatch);
445
446 cmin_flt = sig->cmin_flt;
447 cmaj_flt = sig->cmaj_flt;
448 cutime = sig->cutime;
449 cstime = sig->cstime;
450 cgtime = sig->cgtime;
451 rsslim = ACCESS_ONCE(sig->rlim[RLIMIT_RSS].rlim_cur);
452
453 /* add up live thread stats at the group level */
454 if (whole) {
455 struct task_struct *t = task;
456 do {
457 min_flt += t->min_flt;
458 maj_flt += t->maj_flt;
459 gtime += task_gtime(t);
460 } while_each_thread(task, t);
461
462 min_flt += sig->min_flt;
463 maj_flt += sig->maj_flt;
464 thread_group_cputime_adjusted(task, &utime, &stime);
465 gtime += sig->gtime;
466 }
467
468 sid = task_session_nr_ns(task, ns);
469 ppid = task_tgid_nr_ns(task->real_parent, ns);
470 pgid = task_pgrp_nr_ns(task, ns);
471
472 unlock_task_sighand(task, &flags);
473 }
474
475 if (permitted && (!whole || num_threads < 2))
476 wchan = get_wchan(task);
477 if (!whole) {
478 min_flt = task->min_flt;
479 maj_flt = task->maj_flt;
480 task_cputime_adjusted(task, &utime, &stime);
481 gtime = task_gtime(task);
482 }
483
484 /* scale priority and nice values from timeslices to -20..20 */
485 /* to make it look like a "normal" Unix priority/nice value */
486 priority = task_prio(task);
487 nice = task_nice(task);
488
489 /* convert nsec -> ticks */
490 start_time = nsec_to_clock_t(task->real_start_time);
491
492 seq_printf(m, "%d (%s) %c", pid_nr_ns(pid, ns), tcomm, state);
493 seq_put_decimal_ll(m, ' ', ppid);
494 seq_put_decimal_ll(m, ' ', pgid);
495 seq_put_decimal_ll(m, ' ', sid);
496 seq_put_decimal_ll(m, ' ', tty_nr);
497 seq_put_decimal_ll(m, ' ', tty_pgrp);
498 seq_put_decimal_ull(m, ' ', task->flags);
499 seq_put_decimal_ull(m, ' ', min_flt);
500 seq_put_decimal_ull(m, ' ', cmin_flt);
501 seq_put_decimal_ull(m, ' ', maj_flt);
502 seq_put_decimal_ull(m, ' ', cmaj_flt);
503 seq_put_decimal_ull(m, ' ', cputime_to_clock_t(utime));
504 seq_put_decimal_ull(m, ' ', cputime_to_clock_t(stime));
505 seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cutime));
506 seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cstime));
507 seq_put_decimal_ll(m, ' ', priority);
508 seq_put_decimal_ll(m, ' ', nice);
509 seq_put_decimal_ll(m, ' ', num_threads);
510 seq_put_decimal_ull(m, ' ', 0);
511 seq_put_decimal_ull(m, ' ', start_time);
512 seq_put_decimal_ull(m, ' ', vsize);
513 seq_put_decimal_ull(m, ' ', mm ? get_mm_rss(mm) : 0);
514 seq_put_decimal_ull(m, ' ', rsslim);
515 seq_put_decimal_ull(m, ' ', mm ? (permitted ? mm->start_code : 1) : 0);
516 seq_put_decimal_ull(m, ' ', mm ? (permitted ? mm->end_code : 1) : 0);
517 seq_put_decimal_ull(m, ' ', (permitted && mm) ? mm->start_stack : 0);
518 seq_put_decimal_ull(m, ' ', esp);
519 seq_put_decimal_ull(m, ' ', eip);
520 /* The signal information here is obsolete.
521 * It must be decimal for Linux 2.0 compatibility.
522 * Use /proc/#/status for real-time signals.
523 */
524 seq_put_decimal_ull(m, ' ', task->pending.signal.sig[0] & 0x7fffffffUL);
525 seq_put_decimal_ull(m, ' ', task->blocked.sig[0] & 0x7fffffffUL);
526 seq_put_decimal_ull(m, ' ', sigign.sig[0] & 0x7fffffffUL);
527 seq_put_decimal_ull(m, ' ', sigcatch.sig[0] & 0x7fffffffUL);
528
529 /*
530 * We used to output the absolute kernel address, but that's an
531 * information leak - so instead we show a 0/1 flag here, to signal
532 * to user-space whether there's a wchan field in /proc/PID/wchan.
533 *
534 * This works with older implementations of procps as well.
535 */
536 if (wchan)
537 seq_puts(m, " 1");
538 else
539 seq_puts(m, " 0");
540
541 seq_put_decimal_ull(m, ' ', 0);
542 seq_put_decimal_ull(m, ' ', 0);
543 seq_put_decimal_ll(m, ' ', task->exit_signal);
544 seq_put_decimal_ll(m, ' ', task_cpu(task));
545 seq_put_decimal_ull(m, ' ', task->rt_priority);
546 seq_put_decimal_ull(m, ' ', task->policy);
547 seq_put_decimal_ull(m, ' ', delayacct_blkio_ticks(task));
548 seq_put_decimal_ull(m, ' ', cputime_to_clock_t(gtime));
549 seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cgtime));
550
551 if (mm && permitted) {
552 seq_put_decimal_ull(m, ' ', mm->start_data);
553 seq_put_decimal_ull(m, ' ', mm->end_data);
554 seq_put_decimal_ull(m, ' ', mm->start_brk);
555 seq_put_decimal_ull(m, ' ', mm->arg_start);
556 seq_put_decimal_ull(m, ' ', mm->arg_end);
557 seq_put_decimal_ull(m, ' ', mm->env_start);
558 seq_put_decimal_ull(m, ' ', mm->env_end);
559 } else
560 seq_printf(m, " 0 0 0 0 0 0 0");
561
562 if (permitted)
563 seq_put_decimal_ll(m, ' ', task->exit_code);
564 else
565 seq_put_decimal_ll(m, ' ', 0);
566
567 seq_putc(m, '\n');
568 if (mm)
569 mmput(mm);
570 return 0;
571 }
572
573 int proc_tid_stat(struct seq_file *m, struct pid_namespace *ns,
574 struct pid *pid, struct task_struct *task)
575 {
576 return do_task_stat(m, ns, pid, task, 0);
577 }
578
579 int proc_tgid_stat(struct seq_file *m, struct pid_namespace *ns,
580 struct pid *pid, struct task_struct *task)
581 {
582 return do_task_stat(m, ns, pid, task, 1);
583 }
584
585 int proc_pid_statm(struct seq_file *m, struct pid_namespace *ns,
586 struct pid *pid, struct task_struct *task)
587 {
588 unsigned long size = 0, resident = 0, shared = 0, text = 0, data = 0;
589 struct mm_struct *mm = get_task_mm(task);
590
591 if (mm) {
592 size = task_statm(mm, &shared, &text, &data, &resident);
593 mmput(mm);
594 }
595 /*
596 * For quick read, open code by putting numbers directly
597 * expected format is
598 * seq_printf(m, "%lu %lu %lu %lu 0 %lu 0\n",
599 * size, resident, shared, text, data);
600 */
601 seq_put_decimal_ull(m, 0, size);
602 seq_put_decimal_ull(m, ' ', resident);
603 seq_put_decimal_ull(m, ' ', shared);
604 seq_put_decimal_ull(m, ' ', text);
605 seq_put_decimal_ull(m, ' ', 0);
606 seq_put_decimal_ull(m, ' ', data);
607 seq_put_decimal_ull(m, ' ', 0);
608 seq_putc(m, '\n');
609
610 return 0;
611 }
612
613 #ifdef CONFIG_PROC_CHILDREN
614 static struct pid *
615 get_children_pid(struct inode *inode, struct pid *pid_prev, loff_t pos)
616 {
617 struct task_struct *start, *task;
618 struct pid *pid = NULL;
619
620 read_lock(&tasklist_lock);
621
622 start = pid_task(proc_pid(inode), PIDTYPE_PID);
623 if (!start)
624 goto out;
625
626 /*
627 * Lets try to continue searching first, this gives
628 * us significant speedup on children-rich processes.
629 */
630 if (pid_prev) {
631 task = pid_task(pid_prev, PIDTYPE_PID);
632 if (task && task->real_parent == start &&
633 !(list_empty(&task->sibling))) {
634 if (list_is_last(&task->sibling, &start->children))
635 goto out;
636 task = list_first_entry(&task->sibling,
637 struct task_struct, sibling);
638 pid = get_pid(task_pid(task));
639 goto out;
640 }
641 }
642
643 /*
644 * Slow search case.
645 *
646 * We might miss some children here if children
647 * are exited while we were not holding the lock,
648 * but it was never promised to be accurate that
649 * much.
650 *
651 * "Just suppose that the parent sleeps, but N children
652 * exit after we printed their tids. Now the slow paths
653 * skips N extra children, we miss N tasks." (c)
654 *
655 * So one need to stop or freeze the leader and all
656 * its children to get a precise result.
657 */
658 list_for_each_entry(task, &start->children, sibling) {
659 if (pos-- == 0) {
660 pid = get_pid(task_pid(task));
661 break;
662 }
663 }
664
665 out:
666 read_unlock(&tasklist_lock);
667 return pid;
668 }
669
670 static int children_seq_show(struct seq_file *seq, void *v)
671 {
672 struct inode *inode = seq->private;
673 pid_t pid;
674
675 pid = pid_nr_ns(v, inode->i_sb->s_fs_info);
676 seq_printf(seq, "%d ", pid);
677
678 return 0;
679 }
680
681 static void *children_seq_start(struct seq_file *seq, loff_t *pos)
682 {
683 return get_children_pid(seq->private, NULL, *pos);
684 }
685
686 static void *children_seq_next(struct seq_file *seq, void *v, loff_t *pos)
687 {
688 struct pid *pid;
689
690 pid = get_children_pid(seq->private, v, *pos + 1);
691 put_pid(v);
692
693 ++*pos;
694 return pid;
695 }
696
697 static void children_seq_stop(struct seq_file *seq, void *v)
698 {
699 put_pid(v);
700 }
701
702 static const struct seq_operations children_seq_ops = {
703 .start = children_seq_start,
704 .next = children_seq_next,
705 .stop = children_seq_stop,
706 .show = children_seq_show,
707 };
708
709 static int children_seq_open(struct inode *inode, struct file *file)
710 {
711 struct seq_file *m;
712 int ret;
713
714 ret = seq_open(file, &children_seq_ops);
715 if (ret)
716 return ret;
717
718 m = file->private_data;
719 m->private = inode;
720
721 return ret;
722 }
723
724 int children_seq_release(struct inode *inode, struct file *file)
725 {
726 seq_release(inode, file);
727 return 0;
728 }
729
730 const struct file_operations proc_tid_children_operations = {
731 .open = children_seq_open,
732 .read = seq_read,
733 .llseek = seq_lseek,
734 .release = children_seq_release,
735 };
736 #endif /* CONFIG_PROC_CHILDREN */
Linux with added FPC-III support