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 */ 737