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![Denis V. Lunev](/assets/img/avatar_default.png)
This set of patches fixes an proc ->open'less usage due to ->proc_fops flip in
the most part of the kernel code. The original OOPS is described in the
commit 2d3a4e3666
:
Typical PDE creation code looks like:
pde = create_proc_entry("foo", 0, NULL);
if (pde)
pde->proc_fops = &foo_proc_fops;
Notice that PDE is first created, only then ->proc_fops is set up to
final value. This is a problem because right after creation
a) PDE is fully visible in /proc , and
b) ->proc_fops are proc_file_operations which do not have ->open callback. So, it's
possible to ->read without ->open (see one class of oopses below).
The fix is new API called proc_create() which makes sure ->proc_fops are
set up before gluing PDE to main tree. Typical new code looks like:
pde = proc_create("foo", 0, NULL, &foo_proc_fops);
if (!pde)
return -ENOMEM;
Fix most networking users for a start.
In the long run, create_proc_entry() for regular files will go.
In addition to this, proc_create_data is introduced to fix reading from
proc without PDE->data. The race is basically the same as above.
create_proc_entries is replaced in the entire kernel code as new method
is also simply better.
This patch:
The problem is the same as for de->proc_fops. Right now PDE becomes visible
without data set. So, the entry could be looked up without data. This, in
most cases, will simply OOPS.
proc_create_data call is created to address this issue. proc_create now
becomes a wrapper around it.
Signed-off-by: Denis V. Lunev <den@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Chris Mason <chris.mason@oracle.com>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Grant Grundler <grundler@parisc-linux.org>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jaroslav Kysela <perex@suse.cz>
Cc: Jeff Garzik <jgarzik@pobox.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Karsten Keil <kkeil@suse.de>
Cc: Kyle McMartin <kyle@parisc-linux.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Osterlund <petero2@telia.com>
Cc: Pierre Peiffer <peifferp@gmail.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
234 lines
5 KiB
C
234 lines
5 KiB
C
/*
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* linux/fs/proc/root.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* proc root directory handling functions
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*/
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#include <asm/uaccess.h>
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#include <linux/errno.h>
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#include <linux/time.h>
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#include <linux/proc_fs.h>
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#include <linux/stat.h>
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/module.h>
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#include <linux/bitops.h>
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#include <linux/smp_lock.h>
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#include <linux/mount.h>
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#include <linux/pid_namespace.h>
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#include "internal.h"
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static int proc_test_super(struct super_block *sb, void *data)
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{
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return sb->s_fs_info == data;
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}
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static int proc_set_super(struct super_block *sb, void *data)
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{
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struct pid_namespace *ns;
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ns = (struct pid_namespace *)data;
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sb->s_fs_info = get_pid_ns(ns);
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return set_anon_super(sb, NULL);
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}
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static int proc_get_sb(struct file_system_type *fs_type,
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int flags, const char *dev_name, void *data, struct vfsmount *mnt)
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{
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int err;
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struct super_block *sb;
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struct pid_namespace *ns;
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struct proc_inode *ei;
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if (proc_mnt) {
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/* Seed the root directory with a pid so it doesn't need
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* to be special in base.c. I would do this earlier but
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* the only task alive when /proc is mounted the first time
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* is the init_task and it doesn't have any pids.
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*/
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ei = PROC_I(proc_mnt->mnt_sb->s_root->d_inode);
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if (!ei->pid)
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ei->pid = find_get_pid(1);
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}
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if (flags & MS_KERNMOUNT)
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ns = (struct pid_namespace *)data;
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else
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ns = current->nsproxy->pid_ns;
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sb = sget(fs_type, proc_test_super, proc_set_super, ns);
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if (IS_ERR(sb))
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return PTR_ERR(sb);
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if (!sb->s_root) {
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sb->s_flags = flags;
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err = proc_fill_super(sb);
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if (err) {
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up_write(&sb->s_umount);
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deactivate_super(sb);
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return err;
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}
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ei = PROC_I(sb->s_root->d_inode);
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if (!ei->pid) {
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rcu_read_lock();
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ei->pid = get_pid(find_pid_ns(1, ns));
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rcu_read_unlock();
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}
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sb->s_flags |= MS_ACTIVE;
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ns->proc_mnt = mnt;
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}
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return simple_set_mnt(mnt, sb);
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}
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static void proc_kill_sb(struct super_block *sb)
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{
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struct pid_namespace *ns;
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ns = (struct pid_namespace *)sb->s_fs_info;
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kill_anon_super(sb);
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put_pid_ns(ns);
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}
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static struct file_system_type proc_fs_type = {
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.name = "proc",
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.get_sb = proc_get_sb,
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.kill_sb = proc_kill_sb,
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};
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void __init proc_root_init(void)
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{
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int err = proc_init_inodecache();
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if (err)
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return;
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err = register_filesystem(&proc_fs_type);
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if (err)
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return;
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proc_mnt = kern_mount_data(&proc_fs_type, &init_pid_ns);
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err = PTR_ERR(proc_mnt);
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if (IS_ERR(proc_mnt)) {
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unregister_filesystem(&proc_fs_type);
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return;
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}
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proc_misc_init();
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proc_net_init();
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#ifdef CONFIG_SYSVIPC
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proc_mkdir("sysvipc", NULL);
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#endif
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proc_mkdir("fs", NULL);
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proc_mkdir("driver", NULL);
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proc_mkdir("fs/nfsd", NULL); /* somewhere for the nfsd filesystem to be mounted */
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#if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
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/* just give it a mountpoint */
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proc_mkdir("openprom", NULL);
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#endif
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proc_tty_init();
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#ifdef CONFIG_PROC_DEVICETREE
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proc_device_tree_init();
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#endif
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proc_mkdir("bus", NULL);
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proc_sys_init();
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}
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static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat
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)
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{
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generic_fillattr(dentry->d_inode, stat);
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stat->nlink = proc_root.nlink + nr_processes();
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return 0;
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}
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static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
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{
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if (!proc_lookup(dir, dentry, nd)) {
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return NULL;
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}
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return proc_pid_lookup(dir, dentry, nd);
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}
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static int proc_root_readdir(struct file * filp,
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void * dirent, filldir_t filldir)
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{
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unsigned int nr = filp->f_pos;
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int ret;
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lock_kernel();
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if (nr < FIRST_PROCESS_ENTRY) {
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int error = proc_readdir(filp, dirent, filldir);
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if (error <= 0) {
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unlock_kernel();
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return error;
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}
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filp->f_pos = FIRST_PROCESS_ENTRY;
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}
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unlock_kernel();
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ret = proc_pid_readdir(filp, dirent, filldir);
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return ret;
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}
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/*
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* The root /proc directory is special, as it has the
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* <pid> directories. Thus we don't use the generic
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* directory handling functions for that..
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*/
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static const struct file_operations proc_root_operations = {
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.read = generic_read_dir,
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.readdir = proc_root_readdir,
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};
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/*
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* proc root can do almost nothing..
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*/
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static const struct inode_operations proc_root_inode_operations = {
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.lookup = proc_root_lookup,
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.getattr = proc_root_getattr,
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};
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/*
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* This is the root "inode" in the /proc tree..
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*/
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struct proc_dir_entry proc_root = {
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.low_ino = PROC_ROOT_INO,
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.namelen = 5,
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.name = "/proc",
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.mode = S_IFDIR | S_IRUGO | S_IXUGO,
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.nlink = 2,
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.count = ATOMIC_INIT(1),
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.proc_iops = &proc_root_inode_operations,
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.proc_fops = &proc_root_operations,
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.parent = &proc_root,
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};
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int pid_ns_prepare_proc(struct pid_namespace *ns)
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{
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struct vfsmount *mnt;
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mnt = kern_mount_data(&proc_fs_type, ns);
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if (IS_ERR(mnt))
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return PTR_ERR(mnt);
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return 0;
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}
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void pid_ns_release_proc(struct pid_namespace *ns)
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{
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mntput(ns->proc_mnt);
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}
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EXPORT_SYMBOL(proc_symlink);
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EXPORT_SYMBOL(proc_mkdir);
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EXPORT_SYMBOL(create_proc_entry);
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EXPORT_SYMBOL(proc_create_data);
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EXPORT_SYMBOL(remove_proc_entry);
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