diff options
Diffstat (limited to '')
-rw-r--r-- | fs/proc/array.c | 777 |
1 files changed, 777 insertions, 0 deletions
diff --git a/fs/proc/array.c b/fs/proc/array.c new file mode 100644 index 000000000..18a4588c3 --- /dev/null +++ b/fs/proc/array.c @@ -0,0 +1,777 @@ +// 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/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/uaccess.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/tracehook.h> +#include <linux/string_helpers.h> +#include <linux/user_namespace.h> +#include <linux/fs_struct.h> + +#include <asm/processor.h> +#include "internal.h" + +void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape) +{ + char *buf; + size_t size; + char tcomm[64]; + int ret; + + if (p->flags & PF_WQ_WORKER) + wq_worker_comm(tcomm, sizeof(tcomm), p); + else + __get_task_comm(tcomm, sizeof(tcomm), p); + + size = seq_get_buf(m, &buf); + if (escape) { + ret = string_escape_str(tcomm, buf, size, + ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\"); + if (ret >= size) + ret = -1; + } else { + ret = strscpy(buf, tcomm, size); + } + + seq_commit(m, ret); +} + +/* + * 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 = atomic_read(&__task_cred(p)->user->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_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_ptr)); + seq_printf(m, "Cpus_allowed_list:\t%*pbl\n", + cpumask_pr_args(task->cpus_ptr)); +} + +static inline void task_core_dumping(struct seq_file *m, struct mm_struct *mm) +{ + seq_put_decimal_ull(m, "CoreDumping:\t", !!mm->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, mm); + 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; + + 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; + } + + 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 = get_wchan(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); + + /* convert nsec -> ticks */ + start_time = nsec_to_clock_t(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. + */ + if (wchan) + seq_puts(m, " 1"); + else + seq_puts(m, " 0"); + + 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, " ", task->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 */ |