mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-20 19:18:50 +07:00
2fd1d2c4ce
Andrei Vagin writes: FYI: This bug has been reproduced on 4.11.7 > BUG: Dentry ffff895a3dd01240{i=4e7c09a,n=lo} still in use (1) [unmount of proc proc] > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 13588 at fs/dcache.c:1445 umount_check+0x6e/0x80 > CPU: 1 PID: 13588 Comm: kworker/1:1 Not tainted 4.11.7-200.fc25.x86_64 #1 > Hardware name: CompuLab sbc-flt1/fitlet, BIOS SBCFLT_0.08.04 06/27/2015 > Workqueue: events proc_cleanup_work > Call Trace: > dump_stack+0x63/0x86 > __warn+0xcb/0xf0 > warn_slowpath_null+0x1d/0x20 > umount_check+0x6e/0x80 > d_walk+0xc6/0x270 > ? dentry_free+0x80/0x80 > do_one_tree+0x26/0x40 > shrink_dcache_for_umount+0x2d/0x90 > generic_shutdown_super+0x1f/0xf0 > kill_anon_super+0x12/0x20 > proc_kill_sb+0x40/0x50 > deactivate_locked_super+0x43/0x70 > deactivate_super+0x5a/0x60 > cleanup_mnt+0x3f/0x90 > mntput_no_expire+0x13b/0x190 > kern_unmount+0x3e/0x50 > pid_ns_release_proc+0x15/0x20 > proc_cleanup_work+0x15/0x20 > process_one_work+0x197/0x450 > worker_thread+0x4e/0x4a0 > kthread+0x109/0x140 > ? process_one_work+0x450/0x450 > ? kthread_park+0x90/0x90 > ret_from_fork+0x2c/0x40 > ---[ end trace e1c109611e5d0b41 ]--- > VFS: Busy inodes after unmount of proc. Self-destruct in 5 seconds. Have a nice day... > BUG: unable to handle kernel NULL pointer dereference at (null) > IP: _raw_spin_lock+0xc/0x30 > PGD 0 Fix this by taking a reference to the super block in proc_sys_prune_dcache. The superblock reference is the core of the fix however the sysctl_inodes list is converted to a hlist so that hlist_del_init_rcu may be used. This allows proc_sys_prune_dache to remove inodes the sysctl_inodes list, while not causing problems for proc_sys_evict_inode when if it later choses to remove the inode from the sysctl_inodes list. Removing inodes from the sysctl_inodes list allows proc_sys_prune_dcache to have a progress guarantee, while still being able to drop all locks. The fact that head->unregistering is set in start_unregistering ensures that no more inodes will be added to the the sysctl_inodes list. Previously the code did a dance where it delayed calling iput until the next entry in the list was being considered to ensure the inode remained on the sysctl_inodes list until the next entry was walked to. The structure of the loop in this patch does not need that so is much easier to understand and maintain. Cc: stable@vger.kernel.org Reported-by: Andrei Vagin <avagin@gmail.com> Tested-by: Andrei Vagin <avagin@openvz.org> Fixes:ace0c791e6
("proc/sysctl: Don't grab i_lock under sysctl_lock.") Fixes:d6cffbbe9a
("proc/sysctl: prune stale dentries during unregistering") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
300 lines
8.2 KiB
C
300 lines
8.2 KiB
C
/* Internal procfs definitions
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*
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* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/proc_fs.h>
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#include <linux/proc_ns.h>
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#include <linux/spinlock.h>
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#include <linux/atomic.h>
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#include <linux/binfmts.h>
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#include <linux/sched/coredump.h>
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#include <linux/sched/task.h>
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struct ctl_table_header;
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struct mempolicy;
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/*
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* This is not completely implemented yet. The idea is to
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* create an in-memory tree (like the actual /proc filesystem
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* tree) of these proc_dir_entries, so that we can dynamically
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* add new files to /proc.
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*
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* parent/subdir are used for the directory structure (every /proc file has a
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* parent, but "subdir" is empty for all non-directory entries).
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* subdir_node is used to build the rb tree "subdir" of the parent.
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*/
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struct proc_dir_entry {
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unsigned int low_ino;
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umode_t mode;
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nlink_t nlink;
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kuid_t uid;
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kgid_t gid;
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loff_t size;
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const struct inode_operations *proc_iops;
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const struct file_operations *proc_fops;
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struct proc_dir_entry *parent;
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struct rb_root subdir;
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struct rb_node subdir_node;
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void *data;
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atomic_t count; /* use count */
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atomic_t in_use; /* number of callers into module in progress; */
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/* negative -> it's going away RSN */
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struct completion *pde_unload_completion;
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struct list_head pde_openers; /* who did ->open, but not ->release */
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spinlock_t pde_unload_lock; /* proc_fops checks and pde_users bumps */
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u8 namelen;
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char name[];
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};
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union proc_op {
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int (*proc_get_link)(struct dentry *, struct path *);
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int (*proc_show)(struct seq_file *m,
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struct pid_namespace *ns, struct pid *pid,
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struct task_struct *task);
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};
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struct proc_inode {
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struct pid *pid;
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unsigned int fd;
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union proc_op op;
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struct proc_dir_entry *pde;
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struct ctl_table_header *sysctl;
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struct ctl_table *sysctl_entry;
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struct hlist_node sysctl_inodes;
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const struct proc_ns_operations *ns_ops;
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struct inode vfs_inode;
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};
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/*
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* General functions
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*/
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static inline struct proc_inode *PROC_I(const struct inode *inode)
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{
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return container_of(inode, struct proc_inode, vfs_inode);
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}
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static inline struct proc_dir_entry *PDE(const struct inode *inode)
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{
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return PROC_I(inode)->pde;
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}
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static inline void *__PDE_DATA(const struct inode *inode)
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{
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return PDE(inode)->data;
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}
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static inline struct pid *proc_pid(struct inode *inode)
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{
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return PROC_I(inode)->pid;
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}
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static inline struct task_struct *get_proc_task(struct inode *inode)
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{
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return get_pid_task(proc_pid(inode), PIDTYPE_PID);
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}
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void task_dump_owner(struct task_struct *task, mode_t mode,
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kuid_t *ruid, kgid_t *rgid);
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static inline unsigned name_to_int(const struct qstr *qstr)
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{
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const char *name = qstr->name;
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int len = qstr->len;
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unsigned n = 0;
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if (len > 1 && *name == '0')
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goto out;
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while (len-- > 0) {
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unsigned c = *name++ - '0';
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if (c > 9)
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goto out;
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if (n >= (~0U-9)/10)
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goto out;
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n *= 10;
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n += c;
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}
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return n;
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out:
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return ~0U;
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}
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/*
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* Offset of the first process in the /proc root directory..
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*/
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#define FIRST_PROCESS_ENTRY 256
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/* Worst case buffer size needed for holding an integer. */
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#define PROC_NUMBUF 13
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/*
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* array.c
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*/
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extern const struct file_operations proc_tid_children_operations;
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extern int proc_tid_stat(struct seq_file *, struct pid_namespace *,
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struct pid *, struct task_struct *);
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extern int proc_tgid_stat(struct seq_file *, struct pid_namespace *,
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struct pid *, struct task_struct *);
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extern int proc_pid_status(struct seq_file *, struct pid_namespace *,
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struct pid *, struct task_struct *);
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extern int proc_pid_statm(struct seq_file *, struct pid_namespace *,
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struct pid *, struct task_struct *);
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/*
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* base.c
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*/
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extern const struct dentry_operations pid_dentry_operations;
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extern int pid_getattr(const struct path *, struct kstat *, u32, unsigned int);
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extern int proc_setattr(struct dentry *, struct iattr *);
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extern struct inode *proc_pid_make_inode(struct super_block *, struct task_struct *, umode_t);
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extern int pid_revalidate(struct dentry *, unsigned int);
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extern int pid_delete_dentry(const struct dentry *);
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extern int proc_pid_readdir(struct file *, struct dir_context *);
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extern struct dentry *proc_pid_lookup(struct inode *, struct dentry *, unsigned int);
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extern loff_t mem_lseek(struct file *, loff_t, int);
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/* Lookups */
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typedef int instantiate_t(struct inode *, struct dentry *,
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struct task_struct *, const void *);
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extern bool proc_fill_cache(struct file *, struct dir_context *, const char *, int,
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instantiate_t, struct task_struct *, const void *);
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/*
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* generic.c
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*/
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extern struct dentry *proc_lookup(struct inode *, struct dentry *, unsigned int);
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extern struct dentry *proc_lookup_de(struct proc_dir_entry *, struct inode *,
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struct dentry *);
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extern int proc_readdir(struct file *, struct dir_context *);
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extern int proc_readdir_de(struct proc_dir_entry *, struct file *, struct dir_context *);
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static inline struct proc_dir_entry *pde_get(struct proc_dir_entry *pde)
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{
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atomic_inc(&pde->count);
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return pde;
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}
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extern void pde_put(struct proc_dir_entry *);
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static inline bool is_empty_pde(const struct proc_dir_entry *pde)
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{
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return S_ISDIR(pde->mode) && !pde->proc_iops;
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}
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/*
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* inode.c
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*/
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struct pde_opener {
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struct file *file;
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struct list_head lh;
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bool closing;
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struct completion *c;
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};
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extern const struct inode_operations proc_link_inode_operations;
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extern const struct inode_operations proc_pid_link_inode_operations;
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extern void proc_init_inodecache(void);
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void set_proc_pid_nlink(void);
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extern struct inode *proc_get_inode(struct super_block *, struct proc_dir_entry *);
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extern int proc_fill_super(struct super_block *, void *data, int flags);
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extern void proc_entry_rundown(struct proc_dir_entry *);
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/*
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* proc_namespaces.c
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*/
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extern const struct inode_operations proc_ns_dir_inode_operations;
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extern const struct file_operations proc_ns_dir_operations;
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/*
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* proc_net.c
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*/
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extern const struct file_operations proc_net_operations;
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extern const struct inode_operations proc_net_inode_operations;
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#ifdef CONFIG_NET
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extern int proc_net_init(void);
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#else
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static inline int proc_net_init(void) { return 0; }
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#endif
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/*
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* proc_self.c
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*/
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extern int proc_setup_self(struct super_block *);
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/*
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* proc_thread_self.c
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*/
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extern int proc_setup_thread_self(struct super_block *);
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extern void proc_thread_self_init(void);
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/*
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* proc_sysctl.c
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*/
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#ifdef CONFIG_PROC_SYSCTL
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extern int proc_sys_init(void);
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extern void proc_sys_evict_inode(struct inode *inode,
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struct ctl_table_header *head);
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#else
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static inline void proc_sys_init(void) { }
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static inline void proc_sys_evict_inode(struct inode *inode,
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struct ctl_table_header *head) { }
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#endif
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/*
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* proc_tty.c
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*/
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#ifdef CONFIG_TTY
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extern void proc_tty_init(void);
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#else
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static inline void proc_tty_init(void) {}
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#endif
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/*
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* root.c
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*/
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extern struct proc_dir_entry proc_root;
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extern int proc_parse_options(char *options, struct pid_namespace *pid);
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extern void proc_self_init(void);
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extern int proc_remount(struct super_block *, int *, char *);
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/*
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* task_[no]mmu.c
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*/
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struct proc_maps_private {
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struct inode *inode;
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struct task_struct *task;
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struct mm_struct *mm;
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#ifdef CONFIG_MMU
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struct vm_area_struct *tail_vma;
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#endif
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#ifdef CONFIG_NUMA
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struct mempolicy *task_mempolicy;
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#endif
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};
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struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode);
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extern const struct file_operations proc_pid_maps_operations;
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extern const struct file_operations proc_tid_maps_operations;
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extern const struct file_operations proc_pid_numa_maps_operations;
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extern const struct file_operations proc_tid_numa_maps_operations;
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extern const struct file_operations proc_pid_smaps_operations;
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extern const struct file_operations proc_tid_smaps_operations;
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extern const struct file_operations proc_clear_refs_operations;
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extern const struct file_operations proc_pagemap_operations;
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extern unsigned long task_vsize(struct mm_struct *);
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extern unsigned long task_statm(struct mm_struct *,
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unsigned long *, unsigned long *,
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unsigned long *, unsigned long *);
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extern void task_mem(struct seq_file *, struct mm_struct *);
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