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/sched/mm.h> 64 #include <linux/sched/numa_balancing.h> 65 #include <linux/sched/task.h> 66 #include <linux/sched/cputime.h> 67 #include <linux/proc_fs.h> 68 #include <linux/ioport.h> 69 #include <linux/uaccess.h> 70 #include <linux/io.h> 71 #include <linux/mm.h> 72 #include <linux/hugetlb.h> 73 #include <linux/pagemap.h> 74 #include <linux/swap.h> 75 #include <linux/smp.h> 76 #include <linux/signal.h> 77 #include <linux/highmem.h> 78 #include <linux/file.h> 79 #include <linux/fdtable.h> 80 #include <linux/times.h> 81 #include <linux/cpuset.h> 82 #include <linux/rcupdate.h> 83 #include <linux/delayacct.h> 84 #include <linux/seq_file.h> 85 #include <linux/pid_namespace.h> 86 #include <linux/ptrace.h> 87 #include <linux/tracehook.h> 88 #include <linux/string_helpers.h> 89 #include <linux/user_namespace.h> 90 #include <linux/fs_struct.h> 91 92 #include <asm/pgtable.h> 93 #include <asm/processor.h> 94 #include "internal.h" 95 96 static inline void task_name(struct seq_file *m, struct task_struct *p) 97 { 98 char *buf; 99 size_t size; 100 char tcomm[sizeof(p->comm)]; 101 int ret; 102 103 get_task_comm(tcomm, p); 104 105 seq_puts(m, "Name:\t"); 106 107 size = seq_get_buf(m, &buf); 108 ret = string_escape_str(tcomm, buf, size, ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\"); 109 seq_commit(m, ret < size ? ret : -1); 110 111 seq_putc(m, '\n'); 112 } 113 114 /* 115 * The task state array is a strange "bitmap" of 116 * reasons to sleep. Thus "running" is zero, and 117 * you can test for combinations of others with 118 * simple bit tests. 119 */ 120 static const char * const task_state_array[] = { 121 "R (running)", /* 0 */ 122 "S (sleeping)", /* 1 */ 123 "D (disk sleep)", /* 2 */ 124 "T (stopped)", /* 4 */ 125 "t (tracing stop)", /* 8 */ 126 "X (dead)", /* 16 */ 127 "Z (zombie)", /* 32 */ 128 }; 129 130 static inline const char *get_task_state(struct task_struct *tsk) 131 { 132 unsigned int state = (tsk->state | tsk->exit_state) & TASK_REPORT; 133 134 /* 135 * Parked tasks do not run; they sit in __kthread_parkme(). 136 * Without this check, we would report them as running, which is 137 * clearly wrong, so we report them as sleeping instead. 138 */ 139 if (tsk->state == TASK_PARKED) 140 state = TASK_INTERRUPTIBLE; 141 142 BUILD_BUG_ON(1 + ilog2(TASK_REPORT) != ARRAY_SIZE(task_state_array)-1); 143 144 return task_state_array[fls(state)]; 145 } 146 147 static inline int get_task_umask(struct task_struct *tsk) 148 { 149 struct fs_struct *fs; 150 int umask = -ENOENT; 151 152 task_lock(tsk); 153 fs = tsk->fs; 154 if (fs) 155 umask = fs->umask; 156 task_unlock(tsk); 157 return umask; 158 } 159 160 static inline void task_state(struct seq_file *m, struct pid_namespace *ns, 161 struct pid *pid, struct task_struct *p) 162 { 163 struct user_namespace *user_ns = seq_user_ns(m); 164 struct group_info *group_info; 165 int g, umask; 166 struct task_struct *tracer; 167 const struct cred *cred; 168 pid_t ppid, tpid = 0, tgid, ngid; 169 unsigned int max_fds = 0; 170 171 rcu_read_lock(); 172 ppid = pid_alive(p) ? 173 task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0; 174 175 tracer = ptrace_parent(p); 176 if (tracer) 177 tpid = task_pid_nr_ns(tracer, ns); 178 179 tgid = task_tgid_nr_ns(p, ns); 180 ngid = task_numa_group_id(p); 181 cred = get_task_cred(p); 182 183 umask = get_task_umask(p); 184 if (umask >= 0) 185 seq_printf(m, "Umask:\t%#04o\n", umask); 186 187 task_lock(p); 188 if (p->files) 189 max_fds = files_fdtable(p->files)->max_fds; 190 task_unlock(p); 191 rcu_read_unlock(); 192 193 seq_printf(m, "State:\t%s", get_task_state(p)); 194 195 seq_put_decimal_ull(m, "\nTgid:\t", tgid); 196 seq_put_decimal_ull(m, "\nNgid:\t", ngid); 197 seq_put_decimal_ull(m, "\nPid:\t", pid_nr_ns(pid, ns)); 198 seq_put_decimal_ull(m, "\nPPid:\t", ppid); 199 seq_put_decimal_ull(m, "\nTracerPid:\t", tpid); 200 seq_put_decimal_ull(m, "\nUid:\t", from_kuid_munged(user_ns, cred->uid)); 201 seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->euid)); 202 seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->suid)); 203 seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->fsuid)); 204 seq_put_decimal_ull(m, "\nGid:\t", from_kgid_munged(user_ns, cred->gid)); 205 seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->egid)); 206 seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->sgid)); 207 seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->fsgid)); 208 seq_put_decimal_ull(m, "\nFDSize:\t", max_fds); 209 210 seq_puts(m, "\nGroups:\t"); 211 group_info = cred->group_info; 212 for (g = 0; g < group_info->ngroups; g++) 213 seq_put_decimal_ull(m, g ? " " : "", 214 from_kgid_munged(user_ns, group_info->gid[g])); 215 put_cred(cred); 216 /* Trailing space shouldn't have been added in the first place. */ 217 seq_putc(m, ' '); 218 219 #ifdef CONFIG_PID_NS 220 seq_puts(m, "\nNStgid:"); 221 for (g = ns->level; g <= pid->level; g++) 222 seq_put_decimal_ull(m, "\t", task_tgid_nr_ns(p, pid->numbers[g].ns)); 223 seq_puts(m, "\nNSpid:"); 224 for (g = ns->level; g <= pid->level; g++) 225 seq_put_decimal_ull(m, "\t", 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_put_decimal_ull(m, "\t", task_pgrp_nr_ns(p, pid->numbers[g].ns)); 229 seq_puts(m, "\nNSsid:"); 230 for (g = ns->level; g <= pid->level; g++) 231 seq_put_decimal_ull(m, "\t", task_session_nr_ns(p, pid->numbers[g].ns)); 232 #endif 233 seq_putc(m, '\n'); 234 } 235 236 void render_sigset_t(struct seq_file *m, const char *header, 237 sigset_t *set) 238 { 239 int i; 240 241 seq_puts(m, header); 242 243 i = _NSIG; 244 do { 245 int x = 0; 246 247 i -= 4; 248 if (sigismember(set, i+1)) x |= 1; 249 if (sigismember(set, i+2)) x |= 2; 250 if (sigismember(set, i+3)) x |= 4; 251 if (sigismember(set, i+4)) x |= 8; 252 seq_putc(m, hex_asc[x]); 253 } while (i >= 4); 254 255 seq_putc(m, '\n'); 256 } 257 258 static void collect_sigign_sigcatch(struct task_struct *p, sigset_t *ign, 259 sigset_t *catch) 260 { 261 struct k_sigaction *k; 262 int i; 263 264 k = p->sighand->action; 265 for (i = 1; i <= _NSIG; ++i, ++k) { 266 if (k->sa.sa_handler == SIG_IGN) 267 sigaddset(ign, i); 268 else if (k->sa.sa_handler != SIG_DFL) 269 sigaddset(catch, i); 270 } 271 } 272 273 static inline void task_sig(struct seq_file *m, struct task_struct *p) 274 { 275 unsigned long flags; 276 sigset_t pending, shpending, blocked, ignored, caught; 277 int num_threads = 0; 278 unsigned long qsize = 0; 279 unsigned long qlim = 0; 280 281 sigemptyset(&pending); 282 sigemptyset(&shpending); 283 sigemptyset(&blocked); 284 sigemptyset(&ignored); 285 sigemptyset(&caught); 286 287 if (lock_task_sighand(p, &flags)) { 288 pending = p->pending.signal; 289 shpending = p->signal->shared_pending.signal; 290 blocked = p->blocked; 291 collect_sigign_sigcatch(p, &ignored, &caught); 292 num_threads = get_nr_threads(p); 293 rcu_read_lock(); /* FIXME: is this correct? */ 294 qsize = atomic_read(&__task_cred(p)->user->sigpending); 295 rcu_read_unlock(); 296 qlim = task_rlimit(p, RLIMIT_SIGPENDING); 297 unlock_task_sighand(p, &flags); 298 } 299 300 seq_put_decimal_ull(m, "Threads:\t", num_threads); 301 seq_put_decimal_ull(m, "\nSigQ:\t", qsize); 302 seq_put_decimal_ull(m, "/", qlim); 303 304 /* render them all */ 305 render_sigset_t(m, "\nSigPnd:\t", &pending); 306 render_sigset_t(m, "ShdPnd:\t", &shpending); 307 render_sigset_t(m, "SigBlk:\t", &blocked); 308 render_sigset_t(m, "SigIgn:\t", &ignored); 309 render_sigset_t(m, "SigCgt:\t", &caught); 310 } 311 312 static void render_cap_t(struct seq_file *m, const char *header, 313 kernel_cap_t *a) 314 { 315 unsigned __capi; 316 317 seq_puts(m, header); 318 CAP_FOR_EACH_U32(__capi) { 319 seq_printf(m, "%08x", 320 a->cap[CAP_LAST_U32 - __capi]); 321 } 322 seq_putc(m, '\n'); 323 } 324 325 static inline void task_cap(struct seq_file *m, struct task_struct *p) 326 { 327 const struct cred *cred; 328 kernel_cap_t cap_inheritable, cap_permitted, cap_effective, 329 cap_bset, cap_ambient; 330 331 rcu_read_lock(); 332 cred = __task_cred(p); 333 cap_inheritable = cred->cap_inheritable; 334 cap_permitted = cred->cap_permitted; 335 cap_effective = cred->cap_effective; 336 cap_bset = cred->cap_bset; 337 cap_ambient = cred->cap_ambient; 338 rcu_read_unlock(); 339 340 render_cap_t(m, "CapInh:\t", &cap_inheritable); 341 render_cap_t(m, "CapPrm:\t", &cap_permitted); 342 render_cap_t(m, "CapEff:\t", &cap_effective); 343 render_cap_t(m, "CapBnd:\t", &cap_bset); 344 render_cap_t(m, "CapAmb:\t", &cap_ambient); 345 } 346 347 static inline void task_seccomp(struct seq_file *m, struct task_struct *p) 348 { 349 seq_put_decimal_ull(m, "NoNewPrivs:\t", task_no_new_privs(p)); 350 #ifdef CONFIG_SECCOMP 351 seq_put_decimal_ull(m, "\nSeccomp:\t", p->seccomp.mode); 352 #endif 353 seq_putc(m, '\n'); 354 } 355 356 static inline void task_context_switch_counts(struct seq_file *m, 357 struct task_struct *p) 358 { 359 seq_put_decimal_ull(m, "voluntary_ctxt_switches:\t", p->nvcsw); 360 seq_put_decimal_ull(m, "\nnonvoluntary_ctxt_switches:\t", p->nivcsw); 361 seq_putc(m, '\n'); 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 u64 cutime, cstime, utime, stime; 409 u64 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 /* 421 * esp and eip are intentionally zeroed out. There is no 422 * non-racy way to read them without freezing the task. 423 * Programs that need reliable values can use ptrace(2). 424 */ 425 } 426 427 get_task_comm(tcomm, task); 428 429 sigemptyset(&sigign); 430 sigemptyset(&sigcatch); 431 cutime = cstime = utime = stime = 0; 432 cgtime = gtime = 0; 433 434 if (lock_task_sighand(task, &flags)) { 435 struct signal_struct *sig = task->signal; 436 437 if (sig->tty) { 438 struct pid *pgrp = tty_get_pgrp(sig->tty); 439 tty_pgrp = pid_nr_ns(pgrp, ns); 440 put_pid(pgrp); 441 tty_nr = new_encode_dev(tty_devnum(sig->tty)); 442 } 443 444 num_threads = get_nr_threads(task); 445 collect_sigign_sigcatch(task, &sigign, &sigcatch); 446 447 cmin_flt = sig->cmin_flt; 448 cmaj_flt = sig->cmaj_flt; 449 cutime = sig->cutime; 450 cstime = sig->cstime; 451 cgtime = sig->cgtime; 452 rsslim = ACCESS_ONCE(sig->rlim[RLIMIT_RSS].rlim_cur); 453 454 /* add up live thread stats at the group level */ 455 if (whole) { 456 struct task_struct *t = task; 457 do { 458 min_flt += t->min_flt; 459 maj_flt += t->maj_flt; 460 gtime += task_gtime(t); 461 } while_each_thread(task, t); 462 463 min_flt += sig->min_flt; 464 maj_flt += sig->maj_flt; 465 thread_group_cputime_adjusted(task, &utime, &stime); 466 gtime += sig->gtime; 467 } 468 469 sid = task_session_nr_ns(task, ns); 470 ppid = task_tgid_nr_ns(task->real_parent, ns); 471 pgid = task_pgrp_nr_ns(task, ns); 472 473 unlock_task_sighand(task, &flags); 474 } 475 476 if (permitted && (!whole || num_threads < 2)) 477 wchan = get_wchan(task); 478 if (!whole) { 479 min_flt = task->min_flt; 480 maj_flt = task->maj_flt; 481 task_cputime_adjusted(task, &utime, &stime); 482 gtime = task_gtime(task); 483 } 484 485 /* scale priority and nice values from timeslices to -20..20 */ 486 /* to make it look like a "normal" Unix priority/nice value */ 487 priority = task_prio(task); 488 nice = task_nice(task); 489 490 /* convert nsec -> ticks */ 491 start_time = nsec_to_clock_t(task->real_start_time); 492 493 seq_printf(m, "%d (%s) %c", pid_nr_ns(pid, ns), tcomm, state); 494 seq_put_decimal_ll(m, " ", ppid); 495 seq_put_decimal_ll(m, " ", pgid); 496 seq_put_decimal_ll(m, " ", sid); 497 seq_put_decimal_ll(m, " ", tty_nr); 498 seq_put_decimal_ll(m, " ", tty_pgrp); 499 seq_put_decimal_ull(m, " ", task->flags); 500 seq_put_decimal_ull(m, " ", min_flt); 501 seq_put_decimal_ull(m, " ", cmin_flt); 502 seq_put_decimal_ull(m, " ", maj_flt); 503 seq_put_decimal_ull(m, " ", cmaj_flt); 504 seq_put_decimal_ull(m, " ", nsec_to_clock_t(utime)); 505 seq_put_decimal_ull(m, " ", nsec_to_clock_t(stime)); 506 seq_put_decimal_ll(m, " ", nsec_to_clock_t(cutime)); 507 seq_put_decimal_ll(m, " ", nsec_to_clock_t(cstime)); 508 seq_put_decimal_ll(m, " ", priority); 509 seq_put_decimal_ll(m, " ", nice); 510 seq_put_decimal_ll(m, " ", num_threads); 511 seq_put_decimal_ull(m, " ", 0); 512 seq_put_decimal_ull(m, " ", start_time); 513 seq_put_decimal_ull(m, " ", vsize); 514 seq_put_decimal_ull(m, " ", mm ? get_mm_rss(mm) : 0); 515 seq_put_decimal_ull(m, " ", rsslim); 516 seq_put_decimal_ull(m, " ", mm ? (permitted ? mm->start_code : 1) : 0); 517 seq_put_decimal_ull(m, " ", mm ? (permitted ? mm->end_code : 1) : 0); 518 seq_put_decimal_ull(m, " ", (permitted && mm) ? mm->start_stack : 0); 519 seq_put_decimal_ull(m, " ", esp); 520 seq_put_decimal_ull(m, " ", eip); 521 /* The signal information here is obsolete. 522 * It must be decimal for Linux 2.0 compatibility. 523 * Use /proc/#/status for real-time signals. 524 */ 525 seq_put_decimal_ull(m, " ", task->pending.signal.sig[0] & 0x7fffffffUL); 526 seq_put_decimal_ull(m, " ", task->blocked.sig[0] & 0x7fffffffUL); 527 seq_put_decimal_ull(m, " ", sigign.sig[0] & 0x7fffffffUL); 528 seq_put_decimal_ull(m, " ", sigcatch.sig[0] & 0x7fffffffUL); 529 530 /* 531 * We used to output the absolute kernel address, but that's an 532 * information leak - so instead we show a 0/1 flag here, to signal 533 * to user-space whether there's a wchan field in /proc/PID/wchan. 534 * 535 * This works with older implementations of procps as well. 536 */ 537 if (wchan) 538 seq_puts(m, " 1"); 539 else 540 seq_puts(m, " 0"); 541 542 seq_put_decimal_ull(m, " ", 0); 543 seq_put_decimal_ull(m, " ", 0); 544 seq_put_decimal_ll(m, " ", task->exit_signal); 545 seq_put_decimal_ll(m, " ", task_cpu(task)); 546 seq_put_decimal_ull(m, " ", task->rt_priority); 547 seq_put_decimal_ull(m, " ", task->policy); 548 seq_put_decimal_ull(m, " ", delayacct_blkio_ticks(task)); 549 seq_put_decimal_ull(m, " ", nsec_to_clock_t(gtime)); 550 seq_put_decimal_ll(m, " ", nsec_to_clock_t(cgtime)); 551 552 if (mm && permitted) { 553 seq_put_decimal_ull(m, " ", mm->start_data); 554 seq_put_decimal_ull(m, " ", mm->end_data); 555 seq_put_decimal_ull(m, " ", mm->start_brk); 556 seq_put_decimal_ull(m, " ", mm->arg_start); 557 seq_put_decimal_ull(m, " ", mm->arg_end); 558 seq_put_decimal_ull(m, " ", mm->env_start); 559 seq_put_decimal_ull(m, " ", mm->env_end); 560 } else 561 seq_puts(m, " 0 0 0 0 0 0 0"); 562 563 if (permitted) 564 seq_put_decimal_ll(m, " ", task->exit_code); 565 else 566 seq_puts(m, " 0"); 567 568 seq_putc(m, '\n'); 569 if (mm) 570 mmput(mm); 571 return 0; 572 } 573 574 int proc_tid_stat(struct seq_file *m, struct pid_namespace *ns, 575 struct pid *pid, struct task_struct *task) 576 { 577 return do_task_stat(m, ns, pid, task, 0); 578 } 579 580 int proc_tgid_stat(struct seq_file *m, struct pid_namespace *ns, 581 struct pid *pid, struct task_struct *task) 582 { 583 return do_task_stat(m, ns, pid, task, 1); 584 } 585 586 int proc_pid_statm(struct seq_file *m, struct pid_namespace *ns, 587 struct pid *pid, struct task_struct *task) 588 { 589 unsigned long size = 0, resident = 0, shared = 0, text = 0, data = 0; 590 struct mm_struct *mm = get_task_mm(task); 591 592 if (mm) { 593 size = task_statm(mm, &shared, &text, &data, &resident); 594 mmput(mm); 595 } 596 /* 597 * For quick read, open code by putting numbers directly 598 * expected format is 599 * seq_printf(m, "%lu %lu %lu %lu 0 %lu 0\n", 600 * size, resident, shared, text, data); 601 */ 602 seq_put_decimal_ull(m, "", size); 603 seq_put_decimal_ull(m, " ", resident); 604 seq_put_decimal_ull(m, " ", shared); 605 seq_put_decimal_ull(m, " ", text); 606 seq_put_decimal_ull(m, " ", 0); 607 seq_put_decimal_ull(m, " ", data); 608 seq_put_decimal_ull(m, " ", 0); 609 seq_putc(m, '\n'); 610 611 return 0; 612 } 613 614 #ifdef CONFIG_PROC_CHILDREN 615 static struct pid * 616 get_children_pid(struct inode *inode, struct pid *pid_prev, loff_t pos) 617 { 618 struct task_struct *start, *task; 619 struct pid *pid = NULL; 620 621 read_lock(&tasklist_lock); 622 623 start = pid_task(proc_pid(inode), PIDTYPE_PID); 624 if (!start) 625 goto out; 626 627 /* 628 * Lets try to continue searching first, this gives 629 * us significant speedup on children-rich processes. 630 */ 631 if (pid_prev) { 632 task = pid_task(pid_prev, PIDTYPE_PID); 633 if (task && task->real_parent == start && 634 !(list_empty(&task->sibling))) { 635 if (list_is_last(&task->sibling, &start->children)) 636 goto out; 637 task = list_first_entry(&task->sibling, 638 struct task_struct, sibling); 639 pid = get_pid(task_pid(task)); 640 goto out; 641 } 642 } 643 644 /* 645 * Slow search case. 646 * 647 * We might miss some children here if children 648 * are exited while we were not holding the lock, 649 * but it was never promised to be accurate that 650 * much. 651 * 652 * "Just suppose that the parent sleeps, but N children 653 * exit after we printed their tids. Now the slow paths 654 * skips N extra children, we miss N tasks." (c) 655 * 656 * So one need to stop or freeze the leader and all 657 * its children to get a precise result. 658 */ 659 list_for_each_entry(task, &start->children, sibling) { 660 if (pos-- == 0) { 661 pid = get_pid(task_pid(task)); 662 break; 663 } 664 } 665 666 out: 667 read_unlock(&tasklist_lock); 668 return pid; 669 } 670 671 static int children_seq_show(struct seq_file *seq, void *v) 672 { 673 struct inode *inode = seq->private; 674 pid_t pid; 675 676 pid = pid_nr_ns(v, inode->i_sb->s_fs_info); 677 seq_printf(seq, "%d ", pid); 678 679 return 0; 680 } 681 682 static void *children_seq_start(struct seq_file *seq, loff_t *pos) 683 { 684 return get_children_pid(seq->private, NULL, *pos); 685 } 686 687 static void *children_seq_next(struct seq_file *seq, void *v, loff_t *pos) 688 { 689 struct pid *pid; 690 691 pid = get_children_pid(seq->private, v, *pos + 1); 692 put_pid(v); 693 694 ++*pos; 695 return pid; 696 } 697 698 static void children_seq_stop(struct seq_file *seq, void *v) 699 { 700 put_pid(v); 701 } 702 703 static const struct seq_operations children_seq_ops = { 704 .start = children_seq_start, 705 .next = children_seq_next, 706 .stop = children_seq_stop, 707 .show = children_seq_show, 708 }; 709 710 static int children_seq_open(struct inode *inode, struct file *file) 711 { 712 struct seq_file *m; 713 int ret; 714 715 ret = seq_open(file, &children_seq_ops); 716 if (ret) 717 return ret; 718 719 m = file->private_data; 720 m->private = inode; 721 722 return ret; 723 } 724 725 int children_seq_release(struct inode *inode, struct file *file) 726 { 727 seq_release(inode, file); 728 return 0; 729 } 730 731 const struct file_operations proc_tid_children_operations = { 732 .open = children_seq_open, 733 .read = seq_read, 734 .llseek = seq_lseek, 735 .release = children_seq_release, 736 }; 737 #endif /* CONFIG_PROC_CHILDREN */ 738