// SPDX-License-Identifier: GPL-2.0 /* * linux/fs/proc/array.c * * Copyright (C) 1992 by Linus Torvalds * based on ideas by Darren Senn * * Fixes: * Michael. K. Johnson: stat,statm extensions. * <johnsonm@stolaf.edu> * * Pauline Middelink : Made cmdline,envline only break at '\0's, to * make sure SET_PROCTITLE works. Also removed * bad '!' which forced address recalculation for * EVERY character on the current page. * <middelin@polyware.iaf.nl> * * Danny ter Haar : added cpuinfo * <dth@cistron.nl> * * Alessandro Rubini : profile extension. * <rubini@ipvvis.unipv.it> * * Jeff Tranter : added BogoMips field to cpuinfo * <Jeff_Tranter@Mitel.COM> * * Bruno Haible : remove 4K limit for the maps file * <haible@ma2s2.mathematik.uni-karlsruhe.de> * * Yves Arrouye : remove removal of trailing spaces in get_array. * <Yves.Arrouye@marin.fdn.fr> * * Jerome Forissier : added per-CPU time information to /proc/stat * and /proc/<pid>/cpu extension * <forissier@isia.cma.fr> * - Incorporation and non-SMP safe operation * of forissier patch in 2.1.78 by * Hans Marcus <crowbar@concepts.nl> * * aeb@cwi.nl : /proc/partitions * * * Alan Cox : security fixes. * <alan@lxorguk.ukuu.org.uk> * * Al Viro : safe handling of mm_struct * * Gerhard Wichert : added BIGMEM support * Siemens AG <Gerhard.Wichert@pdb.siemens.de> * * Al Viro & Jeff Garzik : moved most of the thing into base.c and * : proc_misc.c. The rest may eventually go into * : base.c too. */ #include <linux/types.h> #include <linux/errno.h> #include <linux/time.h> #include <linux/time_namespace.h> #include <linux/kernel.h> #include <linux/kernel_stat.h> #include <linux/tty.h> #include <linux/string.h> #include <linux/mman.h> #include <linux/sched/mm.h> #include <linux/sched/numa_balancing.h> #include <linux/sched/task_stack.h> #include <linux/sched/task.h> #include <linux/sched/cputime.h> #include <linux/proc_fs.h> #include <linux/ioport.h> #include <linux/io.h> #include <linux/mm.h> #include <linux/hugetlb.h> #include <linux/pagemap.h> #include <linux/swap.h> #include <linux/smp.h> #include <linux/signal.h> #include <linux/highmem.h> #include <linux/file.h> #include <linux/fdtable.h> #include <linux/times.h> #include <linux/cpuset.h> #include <linux/rcupdate.h> #include <linux/delayacct.h> #include <linux/seq_file.h> #include <linux/pid_namespace.h> #include <linux/prctl.h> #include <linux/ptrace.h> #include <linux/string_helpers.h> #include <linux/user_namespace.h> #include <linux/fs_struct.h> #include <linux/kthread.h> #include <asm/processor.h> #include "internal.h" void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape) { char tcomm[64]; /* * Test before PF_KTHREAD because all workqueue worker threads are * kernel threads. */ if (p->flags & PF_WQ_WORKER) wq_worker_comm(tcomm, sizeof(tcomm), p); else if (p->flags & PF_KTHREAD) get_kthread_comm(tcomm, sizeof(tcomm), p); else __get_task_comm(tcomm, sizeof(tcomm), p); if (escape) seq_escape_str(m, tcomm, ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\"); else seq_printf(m, "%.64s", tcomm); } /* * The task state array is a strange "bitmap" of * reasons to sleep. Thus "running" is zero, and * you can test for combinations of others with * simple bit tests. */ static const char * const task_state_array[] = { /* states in TASK_REPORT: */ "R (running)", /* 0x00 */ "S (sleeping)", /* 0x01 */ "D (disk sleep)", /* 0x02 */ "T (stopped)", /* 0x04 */ "t (tracing stop)", /* 0x08 */ "X (dead)", /* 0x10 */ "Z (zombie)", /* 0x20 */ "P (parked)", /* 0x40 */ /* states beyond TASK_REPORT: */ "I (idle)", /* 0x80 */ }; static inline const char *get_task_state(struct task_struct *tsk) { BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_array)); return task_state_array[task_state_index(tsk)]; } static inline void task_state(struct seq_file *m, struct pid_namespace *ns, struct pid *pid, struct task_struct *p) { struct user_namespace *user_ns = seq_user_ns(m); struct group_info *group_info; int g, umask = -1; struct task_struct *tracer; const struct cred *cred; pid_t ppid, tpid = 0, tgid, ngid; unsigned int max_fds = 0; rcu_read_lock(); ppid = pid_alive(p) ? task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0; tracer = ptrace_parent(p); if (tracer) tpid = task_pid_nr_ns(tracer, ns); tgid = task_tgid_nr_ns(p, ns); ngid = task_numa_group_id(p); cred = get_task_cred(p); task_lock(p); if (p->fs) umask = p->fs->umask; if (p->files) max_fds = files_fdtable(p->files)->max_fds; task_unlock(p); rcu_read_unlock(); if (umask >= 0) seq_printf(m, "Umask:\t%#04o\n", umask); seq_puts(m, "State:\t"); seq_puts(m, get_task_state(p)); seq_put_decimal_ull(m, "\nTgid:\t", tgid); seq_put_decimal_ull(m, "\nNgid:\t", ngid); seq_put_decimal_ull(m, "\nPid:\t", pid_nr_ns(pid, ns)); seq_put_decimal_ull(m, "\nPPid:\t", ppid); seq_put_decimal_ull(m, "\nTracerPid:\t", tpid); seq_put_decimal_ull(m, "\nUid:\t", from_kuid_munged(user_ns, cred->uid)); seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->euid)); seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->suid)); seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->fsuid)); seq_put_decimal_ull(m, "\nGid:\t", from_kgid_munged(user_ns, cred->gid)); seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->egid)); seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->sgid)); seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->fsgid)); seq_put_decimal_ull(m, "\nFDSize:\t", max_fds); seq_puts(m, "\nGroups:\t"); group_info = cred->group_info; for (g = 0; g < group_info->ngroups; g++) seq_put_decimal_ull(m, g ? " " : "", from_kgid_munged(user_ns, group_info->gid[g])); put_cred(cred); /* Trailing space shouldn't have been added in the first place. */ seq_putc(m, ' '); #ifdef CONFIG_PID_NS seq_puts(m, "\nNStgid:"); for (g = ns->level; g <= pid->level; g++) seq_put_decimal_ull(m, "\t", task_tgid_nr_ns(p, pid->numbers[g].ns)); seq_puts(m, "\nNSpid:"); for (g = ns->level; g <= pid->level; g++) seq_put_decimal_ull(m, "\t", task_pid_nr_ns(p, pid->numbers[g].ns)); seq_puts(m, "\nNSpgid:"); for (g = ns->level; g <= pid->level; g++) seq_put_decimal_ull(m, "\t", task_pgrp_nr_ns(p, pid->numbers[g].ns)); seq_puts(m, "\nNSsid:"); for (g = ns->level; g <= pid->level; g++) seq_put_decimal_ull(m, "\t", task_session_nr_ns(p, pid->numbers[g].ns)); #endif seq_putc(m, '\n'); } void render_sigset_t(struct seq_file *m, const char *header, sigset_t *set) { int i; seq_puts(m, header); i = _NSIG; do { int x = 0; i -= 4; if (sigismember(set, i+1)) x |= 1; if (sigismember(set, i+2)) x |= 2; if (sigismember(set, i+3)) x |= 4; if (sigismember(set, i+4)) x |= 8; seq_putc(m, hex_asc[x]); } while (i >= 4); seq_putc(m, '\n'); } static void collect_sigign_sigcatch(struct task_struct *p, sigset_t *sigign, sigset_t *sigcatch) { struct k_sigaction *k; int i; k = p->sighand->action; for (i = 1; i <= _NSIG; ++i, ++k) { if (k->sa.sa_handler == SIG_IGN) sigaddset(sigign, i); else if (k->sa.sa_handler != SIG_DFL) sigaddset(sigcatch, i); } } static inline void task_sig(struct seq_file *m, struct task_struct *p) { unsigned long flags; sigset_t pending, shpending, blocked, ignored, caught; int num_threads = 0; unsigned int qsize = 0; unsigned long qlim = 0; sigemptyset(&pending); sigemptyset(&shpending); sigemptyset(&blocked); sigemptyset(&ignored); sigemptyset(&caught); if (lock_task_sighand(p, &flags)) { pending = p->pending.signal; shpending = p->signal->shared_pending.signal; blocked = p->blocked; collect_sigign_sigcatch(p, &ignored, &caught); num_threads = get_nr_threads(p); rcu_read_lock(); /* FIXME: is this correct? */ qsize = get_rlimit_value(task_ucounts(p), UCOUNT_RLIMIT_SIGPENDING); rcu_read_unlock(); qlim = task_rlimit(p, RLIMIT_SIGPENDING); unlock_task_sighand(p, &flags); } seq_put_decimal_ull(m, "Threads:\t", num_threads); seq_put_decimal_ull(m, "\nSigQ:\t", qsize); seq_put_decimal_ull(m, "/", qlim); /* render them all */ render_sigset_t(m, "\nSigPnd:\t", &pending); render_sigset_t(m, "ShdPnd:\t", &shpending); render_sigset_t(m, "SigBlk:\t", &blocked); render_sigset_t(m, "SigIgn:\t", &ignored); render_sigset_t(m, "SigCgt:\t", &caught); } static void render_cap_t(struct seq_file *m, const char *header, kernel_cap_t *a) { unsigned __capi; seq_puts(m, header); CAP_FOR_EACH_U32(__capi) { seq_put_hex_ll(m, NULL, a->cap[CAP_LAST_U32 - __capi], 8); } seq_putc(m, '\n'); } static inline void task_cap(struct seq_file *m, struct task_struct *p) { const struct cred *cred; kernel_cap_t cap_inheritable, cap_permitted, cap_effective, cap_bset, cap_ambient; rcu_read_lock(); cred = __task_cred(p); cap_inheritable = cred->cap_inheritable; cap_permitted = cred->cap_permitted; cap_effective = cred->cap_effective; cap_bset = cred->cap_bset; cap_ambient = cred->cap_ambient; rcu_read_unlock(); render_cap_t(m, "CapInh:\t", &cap_inheritable); render_cap_t(m, "CapPrm:\t", &cap_permitted); render_cap_t(m, "CapEff:\t", &cap_effective); render_cap_t(m, "CapBnd:\t", &cap_bset); render_cap_t(m, "CapAmb:\t", &cap_ambient); } static inline void task_seccomp(struct seq_file *m, struct task_struct *p) { seq_put_decimal_ull(m, "NoNewPrivs:\t", task_no_new_privs(p)); #ifdef CONFIG_SECCOMP seq_put_decimal_ull(m, "\nSeccomp:\t", p->seccomp.mode); #ifdef CONFIG_SECCOMP_FILTER seq_put_decimal_ull(m, "\nSeccomp_filters:\t", atomic_read(&p->seccomp.filter_count)); #endif #endif seq_puts(m, "\nSpeculation_Store_Bypass:\t"); switch (arch_prctl_spec_ctrl_get(p, PR_SPEC_STORE_BYPASS)) { case -EINVAL: seq_puts(m, "unknown"); break; case PR_SPEC_NOT_AFFECTED: seq_puts(m, "not vulnerable"); break; case PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE: seq_puts(m, "thread force mitigated"); break; case PR_SPEC_PRCTL | PR_SPEC_DISABLE: seq_puts(m, "thread mitigated"); break; case PR_SPEC_PRCTL | PR_SPEC_ENABLE: seq_puts(m, "thread vulnerable"); break; case PR_SPEC_DISABLE: seq_puts(m, "globally mitigated"); break; default: seq_puts(m, "vulnerable"); break; } seq_puts(m, "\nSpeculationIndirectBranch:\t"); switch (arch_prctl_spec_ctrl_get(p, PR_SPEC_INDIRECT_BRANCH)) { case -EINVAL: seq_puts(m, "unsupported"); break; case PR_SPEC_NOT_AFFECTED: seq_puts(m, "not affected"); break; case PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE: seq_puts(m, "conditional force disabled"); break; case PR_SPEC_PRCTL | PR_SPEC_DISABLE: seq_puts(m, "conditional disabled"); break; case PR_SPEC_PRCTL | PR_SPEC_ENABLE: seq_puts(m, "conditional enabled"); break; case PR_SPEC_ENABLE: seq_puts(m, "always enabled"); break; case PR_SPEC_DISABLE: seq_puts(m, "always disabled"); break; default: seq_puts(m, "unknown"); break; } seq_putc(m, '\n'); } static inline void task_context_switch_counts(struct seq_file *m, struct task_struct *p) { seq_put_decimal_ull(m, "voluntary_ctxt_switches:\t", p->nvcsw); seq_put_decimal_ull(m, "\nnonvoluntary_ctxt_switches:\t", p->nivcsw); seq_putc(m, '\n'); } static void task_cpus_allowed(struct seq_file *m, struct task_struct *task) { seq_printf(m, "Cpus_allowed:\t%*pb\n", cpumask_pr_args(&task->cpus_mask)); seq_printf(m, "Cpus_allowed_list:\t%*pbl\n", cpumask_pr_args(&task->cpus_mask)); } static inline void task_core_dumping(struct seq_file *m, struct task_struct *task) { seq_put_decimal_ull(m, "CoreDumping:\t", !!task->signal->core_state); seq_putc(m, '\n'); } static inline void task_thp_status(struct seq_file *m, struct mm_struct *mm) { bool thp_enabled = IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE); if (thp_enabled) thp_enabled = !test_bit(MMF_DISABLE_THP, &mm->flags); seq_printf(m, "THP_enabled:\t%d\n", thp_enabled); } int proc_pid_status(struct seq_file *m, struct pid_namespace *ns, struct pid *pid, struct task_struct *task) { struct mm_struct *mm = get_task_mm(task); seq_puts(m, "Name:\t"); proc_task_name(m, task, true); seq_putc(m, '\n'); task_state(m, ns, pid, task); if (mm) { task_mem(m, mm); task_core_dumping(m, task); task_thp_status(m, mm); mmput(mm); } task_sig(m, task); task_cap(m, task); task_seccomp(m, task); task_cpus_allowed(m, task); cpuset_task_status_allowed(m, task); task_context_switch_counts(m, task); return 0; } static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, struct pid *pid, struct task_struct *task, int whole) { unsigned long vsize, eip, esp, wchan = 0; int priority, nice; int tty_pgrp = -1, tty_nr = 0; sigset_t sigign, sigcatch; char state; pid_t ppid = 0, pgid = -1, sid = -1; int num_threads = 0; int permitted; struct mm_struct *mm; unsigned long long start_time; unsigned long cmin_flt = 0, cmaj_flt = 0; unsigned long min_flt = 0, maj_flt = 0; u64 cutime, cstime, utime, stime; u64 cgtime, gtime; unsigned long rsslim = 0; unsigned long flags; int exit_code = task->exit_code; state = *get_task_state(task); vsize = eip = esp = 0; permitted = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS | PTRACE_MODE_NOAUDIT); mm = get_task_mm(task); if (mm) { vsize = task_vsize(mm); /* * esp and eip are intentionally zeroed out. There is no * non-racy way to read them without freezing the task. * Programs that need reliable values can use ptrace(2). * * The only exception is if the task is core dumping because * a program is not able to use ptrace(2) in that case. It is * safe because the task has stopped executing permanently. */ if (permitted && (task->flags & (PF_EXITING|PF_DUMPCORE))) { if (try_get_task_stack(task)) { eip = KSTK_EIP(task); esp = KSTK_ESP(task); put_task_stack(task); } } } sigemptyset(&sigign); sigemptyset(&sigcatch); cutime = cstime = utime = stime = 0; cgtime = gtime = 0; if (lock_task_sighand(task, &flags)) { struct signal_struct *sig = task->signal; if (sig->tty) { struct pid *pgrp = tty_get_pgrp(sig->tty); tty_pgrp = pid_nr_ns(pgrp, ns); put_pid(pgrp); tty_nr = new_encode_dev(tty_devnum(sig->tty)); } num_threads = get_nr_threads(task); collect_sigign_sigcatch(task, &sigign, &sigcatch); cmin_flt = sig->cmin_flt; cmaj_flt = sig->cmaj_flt; cutime = sig->cutime; cstime = sig->cstime; cgtime = sig->cgtime; rsslim = READ_ONCE(sig->rlim[RLIMIT_RSS].rlim_cur); /* add up live thread stats at the group level */ if (whole) { struct task_struct *t = task; do { min_flt += t->min_flt; maj_flt += t->maj_flt; gtime += task_gtime(t); } while_each_thread(task, t); min_flt += sig->min_flt; maj_flt += sig->maj_flt; thread_group_cputime_adjusted(task, &utime, &stime); gtime += sig->gtime; if (sig->flags & (SIGNAL_GROUP_EXIT | SIGNAL_STOP_STOPPED)) exit_code = sig->group_exit_code; } sid = task_session_nr_ns(task, ns); ppid = task_tgid_nr_ns(task->real_parent, ns); pgid = task_pgrp_nr_ns(task, ns); unlock_task_sighand(task, &flags); } if (permitted && (!whole || num_threads < 2)) wchan = !task_is_running(task); if (!whole) { min_flt = task->min_flt; maj_flt = task->maj_flt; task_cputime_adjusted(task, &utime, &stime); gtime = task_gtime(task); } /* scale priority and nice values from timeslices to -20..20 */ /* to make it look like a "normal" Unix priority/nice value */ priority = task_prio(task); nice = task_nice(task); /* apply timens offset for boottime and convert nsec -> ticks */ start_time = nsec_to_clock_t(timens_add_boottime_ns(task->start_boottime)); seq_put_decimal_ull(m, "", pid_nr_ns(pid, ns)); seq_puts(m, " ("); proc_task_name(m, task, false); seq_puts(m, ") "); seq_putc(m, state); seq_put_decimal_ll(m, " ", ppid); seq_put_decimal_ll(m, " ", pgid); seq_put_decimal_ll(m, " ", sid); seq_put_decimal_ll(m, " ", tty_nr); seq_put_decimal_ll(m, " ", tty_pgrp); seq_put_decimal_ull(m, " ", task->flags); seq_put_decimal_ull(m, " ", min_flt); seq_put_decimal_ull(m, " ", cmin_flt); seq_put_decimal_ull(m, " ", maj_flt); seq_put_decimal_ull(m, " ", cmaj_flt); seq_put_decimal_ull(m, " ", nsec_to_clock_t(utime)); seq_put_decimal_ull(m, " ", nsec_to_clock_t(stime)); seq_put_decimal_ll(m, " ", nsec_to_clock_t(cutime)); seq_put_decimal_ll(m, " ", nsec_to_clock_t(cstime)); seq_put_decimal_ll(m, " ", priority); seq_put_decimal_ll(m, " ", nice); seq_put_decimal_ll(m, " ", num_threads); seq_put_decimal_ull(m, " ", 0); seq_put_decimal_ull(m, " ", start_time); seq_put_decimal_ull(m, " ", vsize); seq_put_decimal_ull(m, " ", mm ? get_mm_rss(mm) : 0); seq_put_decimal_ull(m, " ", rsslim); seq_put_decimal_ull(m, " ", mm ? (permitted ? mm->start_code : 1) : 0); seq_put_decimal_ull(m, " ", mm ? (permitted ? mm->end_code : 1) : 0); seq_put_decimal_ull(m, " ", (permitted && mm) ? mm->start_stack : 0); seq_put_decimal_ull(m, " ", esp); seq_put_decimal_ull(m, " ", eip); /* The signal information here is obsolete. * It must be decimal for Linux 2.0 compatibility. * Use /proc/#/status for real-time signals. */ seq_put_decimal_ull(m, " ", task->pending.signal.sig[0] & 0x7fffffffUL); seq_put_decimal_ull(m, " ", task->blocked.sig[0] & 0x7fffffffUL); seq_put_decimal_ull(m, " ", sigign.sig[0] & 0x7fffffffUL); seq_put_decimal_ull(m, " ", sigcatch.sig[0] & 0x7fffffffUL); /* * We used to output the absolute kernel address, but that's an * information leak - so instead we show a 0/1 flag here, to signal * to user-space whether there's a wchan field in /proc/PID/wchan. * * This works with older implementations of procps as well. */ seq_put_decimal_ull(m, " ", wchan); seq_put_decimal_ull(m, " ", 0); seq_put_decimal_ull(m, " ", 0); seq_put_decimal_ll(m, " ", task->exit_signal); seq_put_decimal_ll(m, " ", task_cpu(task)); seq_put_decimal_ull(m, " ", task->rt_priority); seq_put_decimal_ull(m, " ", task->policy); seq_put_decimal_ull(m, " ", delayacct_blkio_ticks(task)); seq_put_decimal_ull(m, " ", nsec_to_clock_t(gtime)); seq_put_decimal_ll(m, " ", nsec_to_clock_t(cgtime)); if (mm && permitted) { seq_put_decimal_ull(m, " ", mm->start_data); seq_put_decimal_ull(m, " ", mm->end_data); seq_put_decimal_ull(m, " ", mm->start_brk); seq_put_decimal_ull(m, " ", mm->arg_start); seq_put_decimal_ull(m, " ", mm->arg_end); seq_put_decimal_ull(m, " ", mm->env_start); seq_put_decimal_ull(m, " ", mm->env_end); } else seq_puts(m, " 0 0 0 0 0 0 0"); if (permitted) seq_put_decimal_ll(m, " ", exit_code); else seq_puts(m, " 0"); seq_putc(m, '\n'); if (mm) mmput(mm); return 0; } int proc_tid_stat(struct seq_file *m, struct pid_namespace *ns, struct pid *pid, struct task_struct *task) { return do_task_stat(m, ns, pid, task, 0); } int proc_tgid_stat(struct seq_file *m, struct pid_namespace *ns, struct pid *pid, struct task_struct *task) { return do_task_stat(m, ns, pid, task, 1); } int proc_pid_statm(struct seq_file *m, struct pid_namespace *ns, struct pid *pid, struct task_struct *task) { struct mm_struct *mm = get_task_mm(task); if (mm) { unsigned long size; unsigned long resident = 0; unsigned long shared = 0; unsigned long text = 0; unsigned long data = 0; size = task_statm(mm, &shared, &text, &data, &resident); mmput(mm); /* * For quick read, open code by putting numbers directly * expected format is * seq_printf(m, "%lu %lu %lu %lu 0 %lu 0\n", * size, resident, shared, text, data); */ seq_put_decimal_ull(m, "", size); seq_put_decimal_ull(m, " ", resident); seq_put_decimal_ull(m, " ", shared); seq_put_decimal_ull(m, " ", text); seq_put_decimal_ull(m, " ", 0); seq_put_decimal_ull(m, " ", data); seq_put_decimal_ull(m, " ", 0); seq_putc(m, '\n'); } else { seq_write(m, "0 0 0 0 0 0 0\n", 14); } return 0; } #ifdef CONFIG_PROC_CHILDREN static struct pid * get_children_pid(struct inode *inode, struct pid *pid_prev, loff_t pos) { struct task_struct *start, *task; struct pid *pid = NULL; read_lock(&tasklist_lock); start = pid_task(proc_pid(inode), PIDTYPE_PID); if (!start) goto out; /* * Lets try to continue searching first, this gives * us significant speedup on children-rich processes. */ if (pid_prev) { task = pid_task(pid_prev, PIDTYPE_PID); if (task && task->real_parent == start && !(list_empty(&task->sibling))) { if (list_is_last(&task->sibling, &start->children)) goto out; task = list_first_entry(&task->sibling, struct task_struct, sibling); pid = get_pid(task_pid(task)); goto out; } } /* * Slow search case. * * We might miss some children here if children * are exited while we were not holding the lock, * but it was never promised to be accurate that * much. * * "Just suppose that the parent sleeps, but N children * exit after we printed their tids. Now the slow paths * skips N extra children, we miss N tasks." (c) * * So one need to stop or freeze the leader and all * its children to get a precise result. */ list_for_each_entry(task, &start->children, sibling) { if (pos-- == 0) { pid = get_pid(task_pid(task)); break; } } out: read_unlock(&tasklist_lock); return pid; } static int children_seq_show(struct seq_file *seq, void *v) { struct inode *inode = file_inode(seq->file); seq_printf(seq, "%d ", pid_nr_ns(v, proc_pid_ns(inode->i_sb))); return 0; } static void *children_seq_start(struct seq_file *seq, loff_t *pos) { return get_children_pid(file_inode(seq->file), NULL, *pos); } static void *children_seq_next(struct seq_file *seq, void *v, loff_t *pos) { struct pid *pid; pid = get_children_pid(file_inode(seq->file), v, *pos + 1); put_pid(v); ++*pos; return pid; } static void children_seq_stop(struct seq_file *seq, void *v) { put_pid(v); } static const struct seq_operations children_seq_ops = { .start = children_seq_start, .next = children_seq_next, .stop = children_seq_stop, .show = children_seq_show, }; static int children_seq_open(struct inode *inode, struct file *file) { return seq_open(file, &children_seq_ops); } const struct file_operations proc_tid_children_operations = { .open = children_seq_open, .read = seq_read, .llseek = seq_lseek, .release = seq_release, }; #endif /* CONFIG_PROC_CHILDREN */