Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/fs/proc/array.c
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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/user_namespace.h> 85 86 #include <asm/pgtable.h> 87 #include <asm/processor.h> 88 #include "internal.h" 89 90 static inline void task_name(struct seq_file *m, struct task_struct *p) 91 { 92 int i; 93 char *buf, *end; 94 char *name; 95 char tcomm[sizeof(p->comm)]; 96 97 get_task_comm(tcomm, p); 98 99 seq_puts(m, "Name:\t"); 100 end = m->buf + m->size; 101 buf = m->buf + m->count; 102 name = tcomm; 103 i = sizeof(tcomm); 104 while (i && (buf < end)) { 105 unsigned char c = *name; 106 name++; 107 i--; 108 *buf = c; 109 if (!c) 110 break; 111 if (c == '\\') { 112 buf++; 113 if (buf < end) 114 *buf++ = c; 115 continue; 116 } 117 if (c == '\n') { 118 *buf++ = '\\'; 119 if (buf < end) 120 *buf++ = 'n'; 121 continue; 122 } 123 buf++; 124 } 125 m->count = buf - m->buf; 126 seq_putc(m, '\n'); 127 } 128 129 /* 130 * The task state array is a strange "bitmap" of 131 * reasons to sleep. Thus "running" is zero, and 132 * you can test for combinations of others with 133 * simple bit tests. 134 */ 135 static const char * const task_state_array[] = { 136 "R (running)", /* 0 */ 137 "S (sleeping)", /* 1 */ 138 "D (disk sleep)", /* 2 */ 139 "T (stopped)", /* 4 */ 140 "t (tracing stop)", /* 8 */ 141 "Z (zombie)", /* 16 */ 142 "X (dead)", /* 32 */ 143 "x (dead)", /* 64 */ 144 "K (wakekill)", /* 128 */ 145 "W (waking)", /* 256 */ 146 }; 147 148 static inline const char *get_task_state(struct task_struct *tsk) 149 { 150 unsigned int state = (tsk->state & TASK_REPORT) | tsk->exit_state; 151 const char * const *p = &task_state_array[0]; 152 153 BUILD_BUG_ON(1 + ilog2(TASK_STATE_MAX) != ARRAY_SIZE(task_state_array)); 154 155 while (state) { 156 p++; 157 state >>= 1; 158 } 159 return *p; 160 } 161 162 static inline void task_state(struct seq_file *m, struct pid_namespace *ns, 163 struct pid *pid, struct task_struct *p) 164 { 165 struct user_namespace *user_ns = seq_user_ns(m); 166 struct group_info *group_info; 167 int g; 168 struct fdtable *fdt = NULL; 169 const struct cred *cred; 170 pid_t ppid, tpid; 171 172 rcu_read_lock(); 173 ppid = pid_alive(p) ? 174 task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0; 175 tpid = 0; 176 if (pid_alive(p)) { 177 struct task_struct *tracer = ptrace_parent(p); 178 if (tracer) 179 tpid = task_pid_nr_ns(tracer, ns); 180 } 181 cred = get_task_cred(p); 182 seq_printf(m, 183 "State:\t%s\n" 184 "Tgid:\t%d\n" 185 "Pid:\t%d\n" 186 "PPid:\t%d\n" 187 "TracerPid:\t%d\n" 188 "Uid:\t%d\t%d\t%d\t%d\n" 189 "Gid:\t%d\t%d\t%d\t%d\n", 190 get_task_state(p), 191 task_tgid_nr_ns(p, ns), 192 pid_nr_ns(pid, ns), 193 ppid, tpid, 194 from_kuid_munged(user_ns, cred->uid), 195 from_kuid_munged(user_ns, cred->euid), 196 from_kuid_munged(user_ns, cred->suid), 197 from_kuid_munged(user_ns, cred->fsuid), 198 from_kgid_munged(user_ns, cred->gid), 199 from_kgid_munged(user_ns, cred->egid), 200 from_kgid_munged(user_ns, cred->sgid), 201 from_kgid_munged(user_ns, cred->fsgid)); 202 203 task_lock(p); 204 if (p->files) 205 fdt = files_fdtable(p->files); 206 seq_printf(m, 207 "FDSize:\t%d\n" 208 "Groups:\t", 209 fdt ? fdt->max_fds : 0); 210 rcu_read_unlock(); 211 212 group_info = cred->group_info; 213 task_unlock(p); 214 215 for (g = 0; g < group_info->ngroups; g++) 216 seq_printf(m, "%d ", 217 from_kgid_munged(user_ns, GROUP_AT(group_info, g))); 218 put_cred(cred); 219 220 seq_putc(m, '\n'); 221 } 222 223 void render_sigset_t(struct seq_file *m, const char *header, 224 sigset_t *set) 225 { 226 int i; 227 228 seq_puts(m, header); 229 230 i = _NSIG; 231 do { 232 int x = 0; 233 234 i -= 4; 235 if (sigismember(set, i+1)) x |= 1; 236 if (sigismember(set, i+2)) x |= 2; 237 if (sigismember(set, i+3)) x |= 4; 238 if (sigismember(set, i+4)) x |= 8; 239 seq_printf(m, "%x", x); 240 } while (i >= 4); 241 242 seq_putc(m, '\n'); 243 } 244 245 static void collect_sigign_sigcatch(struct task_struct *p, sigset_t *ign, 246 sigset_t *catch) 247 { 248 struct k_sigaction *k; 249 int i; 250 251 k = p->sighand->action; 252 for (i = 1; i <= _NSIG; ++i, ++k) { 253 if (k->sa.sa_handler == SIG_IGN) 254 sigaddset(ign, i); 255 else if (k->sa.sa_handler != SIG_DFL) 256 sigaddset(catch, i); 257 } 258 } 259 260 static inline void task_sig(struct seq_file *m, struct task_struct *p) 261 { 262 unsigned long flags; 263 sigset_t pending, shpending, blocked, ignored, caught; 264 int num_threads = 0; 265 unsigned long qsize = 0; 266 unsigned long qlim = 0; 267 268 sigemptyset(&pending); 269 sigemptyset(&shpending); 270 sigemptyset(&blocked); 271 sigemptyset(&ignored); 272 sigemptyset(&caught); 273 274 if (lock_task_sighand(p, &flags)) { 275 pending = p->pending.signal; 276 shpending = p->signal->shared_pending.signal; 277 blocked = p->blocked; 278 collect_sigign_sigcatch(p, &ignored, &caught); 279 num_threads = get_nr_threads(p); 280 rcu_read_lock(); /* FIXME: is this correct? */ 281 qsize = atomic_read(&__task_cred(p)->user->sigpending); 282 rcu_read_unlock(); 283 qlim = task_rlimit(p, RLIMIT_SIGPENDING); 284 unlock_task_sighand(p, &flags); 285 } 286 287 seq_printf(m, "Threads:\t%d\n", num_threads); 288 seq_printf(m, "SigQ:\t%lu/%lu\n", qsize, qlim); 289 290 /* render them all */ 291 render_sigset_t(m, "SigPnd:\t", &pending); 292 render_sigset_t(m, "ShdPnd:\t", &shpending); 293 render_sigset_t(m, "SigBlk:\t", &blocked); 294 render_sigset_t(m, "SigIgn:\t", &ignored); 295 render_sigset_t(m, "SigCgt:\t", &caught); 296 } 297 298 static void render_cap_t(struct seq_file *m, const char *header, 299 kernel_cap_t *a) 300 { 301 unsigned __capi; 302 303 seq_puts(m, header); 304 CAP_FOR_EACH_U32(__capi) { 305 seq_printf(m, "%08x", 306 a->cap[(_KERNEL_CAPABILITY_U32S-1) - __capi]); 307 } 308 seq_putc(m, '\n'); 309 } 310 311 /* Remove non-existent capabilities */ 312 #define NORM_CAPS(v) (v.cap[CAP_TO_INDEX(CAP_LAST_CAP)] &= \ 313 CAP_TO_MASK(CAP_LAST_CAP + 1) - 1) 314 315 static inline void task_cap(struct seq_file *m, struct task_struct *p) 316 { 317 const struct cred *cred; 318 kernel_cap_t cap_inheritable, cap_permitted, cap_effective, cap_bset; 319 320 rcu_read_lock(); 321 cred = __task_cred(p); 322 cap_inheritable = cred->cap_inheritable; 323 cap_permitted = cred->cap_permitted; 324 cap_effective = cred->cap_effective; 325 cap_bset = cred->cap_bset; 326 rcu_read_unlock(); 327 328 NORM_CAPS(cap_inheritable); 329 NORM_CAPS(cap_permitted); 330 NORM_CAPS(cap_effective); 331 NORM_CAPS(cap_bset); 332 333 render_cap_t(m, "CapInh:\t", &cap_inheritable); 334 render_cap_t(m, "CapPrm:\t", &cap_permitted); 335 render_cap_t(m, "CapEff:\t", &cap_effective); 336 render_cap_t(m, "CapBnd:\t", &cap_bset); 337 } 338 339 static inline void task_seccomp(struct seq_file *m, struct task_struct *p) 340 { 341 #ifdef CONFIG_SECCOMP 342 seq_printf(m, "Seccomp:\t%d\n", p->seccomp.mode); 343 #endif 344 } 345 346 static inline void task_context_switch_counts(struct seq_file *m, 347 struct task_struct *p) 348 { 349 seq_printf(m, "voluntary_ctxt_switches:\t%lu\n" 350 "nonvoluntary_ctxt_switches:\t%lu\n", 351 p->nvcsw, 352 p->nivcsw); 353 } 354 355 static void task_cpus_allowed(struct seq_file *m, struct task_struct *task) 356 { 357 seq_puts(m, "Cpus_allowed:\t"); 358 seq_cpumask(m, &task->cpus_allowed); 359 seq_putc(m, '\n'); 360 seq_puts(m, "Cpus_allowed_list:\t"); 361 seq_cpumask_list(m, &task->cpus_allowed); 362 seq_putc(m, '\n'); 363 } 364 365 int proc_pid_status(struct seq_file *m, struct pid_namespace *ns, 366 struct pid *pid, struct task_struct *task) 367 { 368 struct mm_struct *mm = get_task_mm(task); 369 370 task_name(m, task); 371 task_state(m, ns, pid, task); 372 373 if (mm) { 374 task_mem(m, mm); 375 mmput(mm); 376 } 377 task_sig(m, task); 378 task_cap(m, task); 379 task_seccomp(m, task); 380 task_cpus_allowed(m, task); 381 cpuset_task_status_allowed(m, task); 382 task_context_switch_counts(m, task); 383 return 0; 384 } 385 386 static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, 387 struct pid *pid, struct task_struct *task, int whole) 388 { 389 unsigned long vsize, eip, esp, wchan = ~0UL; 390 int priority, nice; 391 int tty_pgrp = -1, tty_nr = 0; 392 sigset_t sigign, sigcatch; 393 char state; 394 pid_t ppid = 0, pgid = -1, sid = -1; 395 int num_threads = 0; 396 int permitted; 397 struct mm_struct *mm; 398 unsigned long long start_time; 399 unsigned long cmin_flt = 0, cmaj_flt = 0; 400 unsigned long min_flt = 0, maj_flt = 0; 401 cputime_t cutime, cstime, utime, stime; 402 cputime_t cgtime, gtime; 403 unsigned long rsslim = 0; 404 char tcomm[sizeof(task->comm)]; 405 unsigned long flags; 406 407 state = *get_task_state(task); 408 vsize = eip = esp = 0; 409 permitted = ptrace_may_access(task, PTRACE_MODE_READ | PTRACE_MODE_NOAUDIT); 410 mm = get_task_mm(task); 411 if (mm) { 412 vsize = task_vsize(mm); 413 if (permitted) { 414 eip = KSTK_EIP(task); 415 esp = KSTK_ESP(task); 416 } 417 } 418 419 get_task_comm(tcomm, task); 420 421 sigemptyset(&sigign); 422 sigemptyset(&sigcatch); 423 cutime = cstime = utime = stime = 0; 424 cgtime = gtime = 0; 425 426 if (lock_task_sighand(task, &flags)) { 427 struct signal_struct *sig = task->signal; 428 429 if (sig->tty) { 430 struct pid *pgrp = tty_get_pgrp(sig->tty); 431 tty_pgrp = pid_nr_ns(pgrp, ns); 432 put_pid(pgrp); 433 tty_nr = new_encode_dev(tty_devnum(sig->tty)); 434 } 435 436 num_threads = get_nr_threads(task); 437 collect_sigign_sigcatch(task, &sigign, &sigcatch); 438 439 cmin_flt = sig->cmin_flt; 440 cmaj_flt = sig->cmaj_flt; 441 cutime = sig->cutime; 442 cstime = sig->cstime; 443 cgtime = sig->cgtime; 444 rsslim = ACCESS_ONCE(sig->rlim[RLIMIT_RSS].rlim_cur); 445 446 /* add up live thread stats at the group level */ 447 if (whole) { 448 struct task_struct *t = task; 449 do { 450 min_flt += t->min_flt; 451 maj_flt += t->maj_flt; 452 gtime += t->gtime; 453 t = next_thread(t); 454 } while (t != task); 455 456 min_flt += sig->min_flt; 457 maj_flt += sig->maj_flt; 458 thread_group_cputime_adjusted(task, &utime, &stime); 459 gtime += sig->gtime; 460 } 461 462 sid = task_session_nr_ns(task, ns); 463 ppid = task_tgid_nr_ns(task->real_parent, ns); 464 pgid = task_pgrp_nr_ns(task, ns); 465 466 unlock_task_sighand(task, &flags); 467 } 468 469 if (permitted && (!whole || num_threads < 2)) 470 wchan = get_wchan(task); 471 if (!whole) { 472 min_flt = task->min_flt; 473 maj_flt = task->maj_flt; 474 task_cputime_adjusted(task, &utime, &stime); 475 gtime = task->gtime; 476 } 477 478 /* scale priority and nice values from timeslices to -20..20 */ 479 /* to make it look like a "normal" Unix priority/nice value */ 480 priority = task_prio(task); 481 nice = task_nice(task); 482 483 /* Temporary variable needed for gcc-2.96 */ 484 /* convert timespec -> nsec*/ 485 start_time = 486 (unsigned long long)task->real_start_time.tv_sec * NSEC_PER_SEC 487 + task->real_start_time.tv_nsec; 488 /* convert nsec -> ticks */ 489 start_time = nsec_to_clock_t(start_time); 490 491 seq_printf(m, "%d (%s) %c", pid_nr_ns(pid, ns), tcomm, state); 492 seq_put_decimal_ll(m, ' ', ppid); 493 seq_put_decimal_ll(m, ' ', pgid); 494 seq_put_decimal_ll(m, ' ', sid); 495 seq_put_decimal_ll(m, ' ', tty_nr); 496 seq_put_decimal_ll(m, ' ', tty_pgrp); 497 seq_put_decimal_ull(m, ' ', task->flags); 498 seq_put_decimal_ull(m, ' ', min_flt); 499 seq_put_decimal_ull(m, ' ', cmin_flt); 500 seq_put_decimal_ull(m, ' ', maj_flt); 501 seq_put_decimal_ull(m, ' ', cmaj_flt); 502 seq_put_decimal_ull(m, ' ', cputime_to_clock_t(utime)); 503 seq_put_decimal_ull(m, ' ', cputime_to_clock_t(stime)); 504 seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cutime)); 505 seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cstime)); 506 seq_put_decimal_ll(m, ' ', priority); 507 seq_put_decimal_ll(m, ' ', nice); 508 seq_put_decimal_ll(m, ' ', num_threads); 509 seq_put_decimal_ull(m, ' ', 0); 510 seq_put_decimal_ull(m, ' ', start_time); 511 seq_put_decimal_ull(m, ' ', vsize); 512 seq_put_decimal_ull(m, ' ', mm ? get_mm_rss(mm) : 0); 513 seq_put_decimal_ull(m, ' ', rsslim); 514 seq_put_decimal_ull(m, ' ', mm ? (permitted ? mm->start_code : 1) : 0); 515 seq_put_decimal_ull(m, ' ', mm ? (permitted ? mm->end_code : 1) : 0); 516 seq_put_decimal_ull(m, ' ', (permitted && mm) ? mm->start_stack : 0); 517 seq_put_decimal_ull(m, ' ', esp); 518 seq_put_decimal_ull(m, ' ', eip); 519 /* The signal information here is obsolete. 520 * It must be decimal for Linux 2.0 compatibility. 521 * Use /proc/#/status for real-time signals. 522 */ 523 seq_put_decimal_ull(m, ' ', task->pending.signal.sig[0] & 0x7fffffffUL); 524 seq_put_decimal_ull(m, ' ', task->blocked.sig[0] & 0x7fffffffUL); 525 seq_put_decimal_ull(m, ' ', sigign.sig[0] & 0x7fffffffUL); 526 seq_put_decimal_ull(m, ' ', sigcatch.sig[0] & 0x7fffffffUL); 527 seq_put_decimal_ull(m, ' ', wchan); 528 seq_put_decimal_ull(m, ' ', 0); 529 seq_put_decimal_ull(m, ' ', 0); 530 seq_put_decimal_ll(m, ' ', task->exit_signal); 531 seq_put_decimal_ll(m, ' ', task_cpu(task)); 532 seq_put_decimal_ull(m, ' ', task->rt_priority); 533 seq_put_decimal_ull(m, ' ', task->policy); 534 seq_put_decimal_ull(m, ' ', delayacct_blkio_ticks(task)); 535 seq_put_decimal_ull(m, ' ', cputime_to_clock_t(gtime)); 536 seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cgtime)); 537 538 if (mm && permitted) { 539 seq_put_decimal_ull(m, ' ', mm->start_data); 540 seq_put_decimal_ull(m, ' ', mm->end_data); 541 seq_put_decimal_ull(m, ' ', mm->start_brk); 542 seq_put_decimal_ull(m, ' ', mm->arg_start); 543 seq_put_decimal_ull(m, ' ', mm->arg_end); 544 seq_put_decimal_ull(m, ' ', mm->env_start); 545 seq_put_decimal_ull(m, ' ', mm->env_end); 546 } else 547 seq_printf(m, " 0 0 0 0 0 0 0"); 548 549 if (permitted) 550 seq_put_decimal_ll(m, ' ', task->exit_code); 551 else 552 seq_put_decimal_ll(m, ' ', 0); 553 554 seq_putc(m, '\n'); 555 if (mm) 556 mmput(mm); 557 return 0; 558 } 559 560 int proc_tid_stat(struct seq_file *m, struct pid_namespace *ns, 561 struct pid *pid, struct task_struct *task) 562 { 563 return do_task_stat(m, ns, pid, task, 0); 564 } 565 566 int proc_tgid_stat(struct seq_file *m, struct pid_namespace *ns, 567 struct pid *pid, struct task_struct *task) 568 { 569 return do_task_stat(m, ns, pid, task, 1); 570 } 571 572 int proc_pid_statm(struct seq_file *m, struct pid_namespace *ns, 573 struct pid *pid, struct task_struct *task) 574 { 575 unsigned long size = 0, resident = 0, shared = 0, text = 0, data = 0; 576 struct mm_struct *mm = get_task_mm(task); 577 578 if (mm) { 579 size = task_statm(mm, &shared, &text, &data, &resident); 580 mmput(mm); 581 } 582 /* 583 * For quick read, open code by putting numbers directly 584 * expected format is 585 * seq_printf(m, "%lu %lu %lu %lu 0 %lu 0\n", 586 * size, resident, shared, text, data); 587 */ 588 seq_put_decimal_ull(m, 0, size); 589 seq_put_decimal_ull(m, ' ', resident); 590 seq_put_decimal_ull(m, ' ', shared); 591 seq_put_decimal_ull(m, ' ', text); 592 seq_put_decimal_ull(m, ' ', 0); 593 seq_put_decimal_ull(m, ' ', data); 594 seq_put_decimal_ull(m, ' ', 0); 595 seq_putc(m, '\n'); 596 597 return 0; 598 } 599 600 #ifdef CONFIG_CHECKPOINT_RESTORE 601 static struct pid * 602 get_children_pid(struct inode *inode, struct pid *pid_prev, loff_t pos) 603 { 604 struct task_struct *start, *task; 605 struct pid *pid = NULL; 606 607 read_lock(&tasklist_lock); 608 609 start = pid_task(proc_pid(inode), PIDTYPE_PID); 610 if (!start) 611 goto out; 612 613 /* 614 * Lets try to continue searching first, this gives 615 * us significant speedup on children-rich processes. 616 */ 617 if (pid_prev) { 618 task = pid_task(pid_prev, PIDTYPE_PID); 619 if (task && task->real_parent == start && 620 !(list_empty(&task->sibling))) { 621 if (list_is_last(&task->sibling, &start->children)) 622 goto out; 623 task = list_first_entry(&task->sibling, 624 struct task_struct, sibling); 625 pid = get_pid(task_pid(task)); 626 goto out; 627 } 628 } 629 630 /* 631 * Slow search case. 632 * 633 * We might miss some children here if children 634 * are exited while we were not holding the lock, 635 * but it was never promised to be accurate that 636 * much. 637 * 638 * "Just suppose that the parent sleeps, but N children 639 * exit after we printed their tids. Now the slow paths 640 * skips N extra children, we miss N tasks." (c) 641 * 642 * So one need to stop or freeze the leader and all 643 * its children to get a precise result. 644 */ 645 list_for_each_entry(task, &start->children, sibling) { 646 if (pos-- == 0) { 647 pid = get_pid(task_pid(task)); 648 break; 649 } 650 } 651 652 out: 653 read_unlock(&tasklist_lock); 654 return pid; 655 } 656 657 static int children_seq_show(struct seq_file *seq, void *v) 658 { 659 struct inode *inode = seq->private; 660 pid_t pid; 661 662 pid = pid_nr_ns(v, inode->i_sb->s_fs_info); 663 return seq_printf(seq, "%d ", pid); 664 } 665 666 static void *children_seq_start(struct seq_file *seq, loff_t *pos) 667 { 668 return get_children_pid(seq->private, NULL, *pos); 669 } 670 671 static void *children_seq_next(struct seq_file *seq, void *v, loff_t *pos) 672 { 673 struct pid *pid; 674 675 pid = get_children_pid(seq->private, v, *pos + 1); 676 put_pid(v); 677 678 ++*pos; 679 return pid; 680 } 681 682 static void children_seq_stop(struct seq_file *seq, void *v) 683 { 684 put_pid(v); 685 } 686 687 static const struct seq_operations children_seq_ops = { 688 .start = children_seq_start, 689 .next = children_seq_next, 690 .stop = children_seq_stop, 691 .show = children_seq_show, 692 }; 693 694 static int children_seq_open(struct inode *inode, struct file *file) 695 { 696 struct seq_file *m; 697 int ret; 698 699 ret = seq_open(file, &children_seq_ops); 700 if (ret) 701 return ret; 702 703 m = file->private_data; 704 m->private = inode; 705 706 return ret; 707 } 708 709 int children_seq_release(struct inode *inode, struct file *file) 710 { 711 seq_release(inode, file); 712 return 0; 713 } 714 715 const struct file_operations proc_tid_children_operations = { 716 .open = children_seq_open, 717 .read = seq_read, 718 .llseek = seq_lseek, 719 .release = children_seq_release, 720 }; 721 #endif /* CONFIG_CHECKPOINT_RESTORE */
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