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