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![Alexey Dobriyan](/assets/img/avatar_default.png)
Currently core /proc code uses "struct file_operations" for custom hooks, however, VFS doesn't directly call them. Every time VFS expands file_operations hook set, /proc code bloats for no reason. Introduce "struct proc_ops" which contains only those hooks which /proc allows to call into (open, release, read, write, ioctl, mmap, poll). It doesn't contain module pointer as well. Save ~184 bytes per usage: add/remove: 26/26 grow/shrink: 1/4 up/down: 1922/-6674 (-4752) Function old new delta sysvipc_proc_ops - 72 +72 ... config_gz_proc_ops - 72 +72 proc_get_inode 289 339 +50 proc_reg_get_unmapped_area 110 107 -3 close_pdeo 227 224 -3 proc_reg_open 289 284 -5 proc_create_data 60 53 -7 rt_cpu_seq_fops 256 - -256 ... default_affinity_proc_fops 256 - -256 Total: Before=5430095, After=5425343, chg -0.09% Link: http://lkml.kernel.org/r/20191225172228.GA13378@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
491 lines
12 KiB
C
491 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/fs/proc/inode.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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#include <linux/cache.h>
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#include <linux/time.h>
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#include <linux/proc_fs.h>
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#include <linux/kernel.h>
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#include <linux/pid_namespace.h>
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#include <linux/mm.h>
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#include <linux/string.h>
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#include <linux/stat.h>
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#include <linux/completion.h>
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#include <linux/poll.h>
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#include <linux/printk.h>
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#include <linux/file.h>
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#include <linux/limits.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/sysctl.h>
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#include <linux/seq_file.h>
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#include <linux/slab.h>
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#include <linux/mount.h>
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#include <linux/uaccess.h>
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#include "internal.h"
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static void proc_evict_inode(struct inode *inode)
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{
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struct proc_dir_entry *de;
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struct ctl_table_header *head;
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truncate_inode_pages_final(&inode->i_data);
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clear_inode(inode);
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/* Stop tracking associated processes */
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put_pid(PROC_I(inode)->pid);
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/* Let go of any associated proc directory entry */
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de = PDE(inode);
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if (de)
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pde_put(de);
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head = PROC_I(inode)->sysctl;
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if (head) {
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RCU_INIT_POINTER(PROC_I(inode)->sysctl, NULL);
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proc_sys_evict_inode(inode, head);
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}
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}
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static struct kmem_cache *proc_inode_cachep __ro_after_init;
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static struct kmem_cache *pde_opener_cache __ro_after_init;
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static struct inode *proc_alloc_inode(struct super_block *sb)
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{
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struct proc_inode *ei;
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ei = kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
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if (!ei)
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return NULL;
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ei->pid = NULL;
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ei->fd = 0;
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ei->op.proc_get_link = NULL;
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ei->pde = NULL;
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ei->sysctl = NULL;
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ei->sysctl_entry = NULL;
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ei->ns_ops = NULL;
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return &ei->vfs_inode;
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}
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static void proc_free_inode(struct inode *inode)
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{
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kmem_cache_free(proc_inode_cachep, PROC_I(inode));
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}
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static void init_once(void *foo)
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{
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struct proc_inode *ei = (struct proc_inode *) foo;
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inode_init_once(&ei->vfs_inode);
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}
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void __init proc_init_kmemcache(void)
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{
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proc_inode_cachep = kmem_cache_create("proc_inode_cache",
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sizeof(struct proc_inode),
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0, (SLAB_RECLAIM_ACCOUNT|
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SLAB_MEM_SPREAD|SLAB_ACCOUNT|
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SLAB_PANIC),
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init_once);
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pde_opener_cache =
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kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0,
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SLAB_ACCOUNT|SLAB_PANIC, NULL);
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proc_dir_entry_cache = kmem_cache_create_usercopy(
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"proc_dir_entry", SIZEOF_PDE, 0, SLAB_PANIC,
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offsetof(struct proc_dir_entry, inline_name),
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SIZEOF_PDE_INLINE_NAME, NULL);
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BUILD_BUG_ON(sizeof(struct proc_dir_entry) >= SIZEOF_PDE);
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}
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static int proc_show_options(struct seq_file *seq, struct dentry *root)
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{
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struct super_block *sb = root->d_sb;
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struct pid_namespace *pid = sb->s_fs_info;
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if (!gid_eq(pid->pid_gid, GLOBAL_ROOT_GID))
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seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, pid->pid_gid));
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if (pid->hide_pid != HIDEPID_OFF)
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seq_printf(seq, ",hidepid=%u", pid->hide_pid);
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return 0;
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}
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const struct super_operations proc_sops = {
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.alloc_inode = proc_alloc_inode,
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.free_inode = proc_free_inode,
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.drop_inode = generic_delete_inode,
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.evict_inode = proc_evict_inode,
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.statfs = simple_statfs,
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.show_options = proc_show_options,
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};
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enum {BIAS = -1U<<31};
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static inline int use_pde(struct proc_dir_entry *pde)
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{
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return likely(atomic_inc_unless_negative(&pde->in_use));
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}
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static void unuse_pde(struct proc_dir_entry *pde)
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{
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if (unlikely(atomic_dec_return(&pde->in_use) == BIAS))
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complete(pde->pde_unload_completion);
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}
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/* pde is locked on entry, unlocked on exit */
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static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
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{
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/*
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* close() (proc_reg_release()) can't delete an entry and proceed:
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* ->release hook needs to be available at the right moment.
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*
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* rmmod (remove_proc_entry() et al) can't delete an entry and proceed:
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* "struct file" needs to be available at the right moment.
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*
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* Therefore, first process to enter this function does ->release() and
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* signals its completion to the other process which does nothing.
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*/
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if (pdeo->closing) {
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/* somebody else is doing that, just wait */
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DECLARE_COMPLETION_ONSTACK(c);
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pdeo->c = &c;
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spin_unlock(&pde->pde_unload_lock);
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wait_for_completion(&c);
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} else {
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struct file *file;
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struct completion *c;
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pdeo->closing = true;
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spin_unlock(&pde->pde_unload_lock);
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file = pdeo->file;
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pde->proc_ops->proc_release(file_inode(file), file);
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spin_lock(&pde->pde_unload_lock);
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/* After ->release. */
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list_del(&pdeo->lh);
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c = pdeo->c;
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spin_unlock(&pde->pde_unload_lock);
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if (unlikely(c))
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complete(c);
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kmem_cache_free(pde_opener_cache, pdeo);
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}
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}
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void proc_entry_rundown(struct proc_dir_entry *de)
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{
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DECLARE_COMPLETION_ONSTACK(c);
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/* Wait until all existing callers into module are done. */
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de->pde_unload_completion = &c;
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if (atomic_add_return(BIAS, &de->in_use) != BIAS)
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wait_for_completion(&c);
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/* ->pde_openers list can't grow from now on. */
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spin_lock(&de->pde_unload_lock);
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while (!list_empty(&de->pde_openers)) {
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struct pde_opener *pdeo;
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pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
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close_pdeo(de, pdeo);
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spin_lock(&de->pde_unload_lock);
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}
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spin_unlock(&de->pde_unload_lock);
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}
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static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
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{
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struct proc_dir_entry *pde = PDE(file_inode(file));
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loff_t rv = -EINVAL;
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if (use_pde(pde)) {
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typeof_member(struct proc_ops, proc_lseek) lseek;
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lseek = pde->proc_ops->proc_lseek;
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if (!lseek)
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lseek = default_llseek;
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rv = lseek(file, offset, whence);
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unuse_pde(pde);
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}
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return rv;
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}
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static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
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{
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struct proc_dir_entry *pde = PDE(file_inode(file));
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ssize_t rv = -EIO;
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if (use_pde(pde)) {
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typeof_member(struct proc_ops, proc_read) read;
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read = pde->proc_ops->proc_read;
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if (read)
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rv = read(file, buf, count, ppos);
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unuse_pde(pde);
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}
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return rv;
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}
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static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
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{
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struct proc_dir_entry *pde = PDE(file_inode(file));
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ssize_t rv = -EIO;
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if (use_pde(pde)) {
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typeof_member(struct proc_ops, proc_write) write;
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write = pde->proc_ops->proc_write;
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if (write)
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rv = write(file, buf, count, ppos);
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unuse_pde(pde);
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}
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return rv;
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}
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static __poll_t proc_reg_poll(struct file *file, struct poll_table_struct *pts)
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{
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struct proc_dir_entry *pde = PDE(file_inode(file));
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__poll_t rv = DEFAULT_POLLMASK;
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if (use_pde(pde)) {
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typeof_member(struct proc_ops, proc_poll) poll;
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poll = pde->proc_ops->proc_poll;
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if (poll)
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rv = poll(file, pts);
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unuse_pde(pde);
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}
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return rv;
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}
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static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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{
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struct proc_dir_entry *pde = PDE(file_inode(file));
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long rv = -ENOTTY;
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if (use_pde(pde)) {
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typeof_member(struct proc_ops, proc_ioctl) ioctl;
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ioctl = pde->proc_ops->proc_ioctl;
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if (ioctl)
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rv = ioctl(file, cmd, arg);
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unuse_pde(pde);
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}
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return rv;
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}
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#ifdef CONFIG_COMPAT
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static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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{
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struct proc_dir_entry *pde = PDE(file_inode(file));
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long rv = -ENOTTY;
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if (use_pde(pde)) {
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typeof_member(struct proc_ops, proc_compat_ioctl) compat_ioctl;
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compat_ioctl = pde->proc_ops->proc_compat_ioctl;
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if (compat_ioctl)
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rv = compat_ioctl(file, cmd, arg);
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unuse_pde(pde);
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}
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return rv;
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}
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#endif
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static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
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{
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struct proc_dir_entry *pde = PDE(file_inode(file));
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int rv = -EIO;
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if (use_pde(pde)) {
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typeof_member(struct proc_ops, proc_mmap) mmap;
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mmap = pde->proc_ops->proc_mmap;
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if (mmap)
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rv = mmap(file, vma);
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unuse_pde(pde);
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}
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return rv;
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}
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static unsigned long
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proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr,
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unsigned long len, unsigned long pgoff,
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unsigned long flags)
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{
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struct proc_dir_entry *pde = PDE(file_inode(file));
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unsigned long rv = -EIO;
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if (use_pde(pde)) {
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typeof_member(struct proc_ops, proc_get_unmapped_area) get_area;
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get_area = pde->proc_ops->proc_get_unmapped_area;
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#ifdef CONFIG_MMU
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if (!get_area)
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get_area = current->mm->get_unmapped_area;
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#endif
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if (get_area)
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rv = get_area(file, orig_addr, len, pgoff, flags);
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else
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rv = orig_addr;
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unuse_pde(pde);
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}
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return rv;
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}
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static int proc_reg_open(struct inode *inode, struct file *file)
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{
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struct proc_dir_entry *pde = PDE(inode);
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int rv = 0;
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typeof_member(struct proc_ops, proc_open) open;
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typeof_member(struct proc_ops, proc_release) release;
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struct pde_opener *pdeo;
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/*
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* Ensure that
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* 1) PDE's ->release hook will be called no matter what
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* either normally by close()/->release, or forcefully by
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* rmmod/remove_proc_entry.
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*
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* 2) rmmod isn't blocked by opening file in /proc and sitting on
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* the descriptor (including "rmmod foo </proc/foo" scenario).
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*
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* Save every "struct file" with custom ->release hook.
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*/
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if (!use_pde(pde))
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return -ENOENT;
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release = pde->proc_ops->proc_release;
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if (release) {
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pdeo = kmem_cache_alloc(pde_opener_cache, GFP_KERNEL);
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if (!pdeo) {
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rv = -ENOMEM;
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goto out_unuse;
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}
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}
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open = pde->proc_ops->proc_open;
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if (open)
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rv = open(inode, file);
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if (release) {
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if (rv == 0) {
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/* To know what to release. */
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pdeo->file = file;
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pdeo->closing = false;
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pdeo->c = NULL;
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spin_lock(&pde->pde_unload_lock);
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list_add(&pdeo->lh, &pde->pde_openers);
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spin_unlock(&pde->pde_unload_lock);
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} else
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kmem_cache_free(pde_opener_cache, pdeo);
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}
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out_unuse:
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unuse_pde(pde);
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return rv;
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}
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static int proc_reg_release(struct inode *inode, struct file *file)
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{
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struct proc_dir_entry *pde = PDE(inode);
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struct pde_opener *pdeo;
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spin_lock(&pde->pde_unload_lock);
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list_for_each_entry(pdeo, &pde->pde_openers, lh) {
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if (pdeo->file == file) {
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close_pdeo(pde, pdeo);
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return 0;
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}
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}
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spin_unlock(&pde->pde_unload_lock);
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return 0;
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}
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static const struct file_operations proc_reg_file_ops = {
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.llseek = proc_reg_llseek,
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.read = proc_reg_read,
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.write = proc_reg_write,
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.poll = proc_reg_poll,
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.unlocked_ioctl = proc_reg_unlocked_ioctl,
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#ifdef CONFIG_COMPAT
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.compat_ioctl = proc_reg_compat_ioctl,
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#endif
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.mmap = proc_reg_mmap,
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.get_unmapped_area = proc_reg_get_unmapped_area,
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.open = proc_reg_open,
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.release = proc_reg_release,
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};
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#ifdef CONFIG_COMPAT
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static const struct file_operations proc_reg_file_ops_no_compat = {
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.llseek = proc_reg_llseek,
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.read = proc_reg_read,
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.write = proc_reg_write,
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.poll = proc_reg_poll,
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.unlocked_ioctl = proc_reg_unlocked_ioctl,
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.mmap = proc_reg_mmap,
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.get_unmapped_area = proc_reg_get_unmapped_area,
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.open = proc_reg_open,
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.release = proc_reg_release,
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};
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#endif
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static void proc_put_link(void *p)
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{
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unuse_pde(p);
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}
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static const char *proc_get_link(struct dentry *dentry,
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struct inode *inode,
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struct delayed_call *done)
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{
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struct proc_dir_entry *pde = PDE(inode);
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if (!use_pde(pde))
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return ERR_PTR(-EINVAL);
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set_delayed_call(done, proc_put_link, pde);
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return pde->data;
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}
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const struct inode_operations proc_link_inode_operations = {
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.get_link = proc_get_link,
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};
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struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
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{
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struct inode *inode = new_inode_pseudo(sb);
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if (inode) {
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inode->i_ino = de->low_ino;
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inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
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PROC_I(inode)->pde = de;
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if (is_empty_pde(de)) {
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make_empty_dir_inode(inode);
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return inode;
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}
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if (de->mode) {
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inode->i_mode = de->mode;
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inode->i_uid = de->uid;
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inode->i_gid = de->gid;
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}
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if (de->size)
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inode->i_size = de->size;
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if (de->nlink)
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set_nlink(inode, de->nlink);
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if (S_ISREG(inode->i_mode)) {
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inode->i_op = de->proc_iops;
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inode->i_fop = &proc_reg_file_ops;
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#ifdef CONFIG_COMPAT
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if (!de->proc_ops->proc_compat_ioctl) {
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inode->i_fop = &proc_reg_file_ops_no_compat;
|
|
}
|
|
#endif
|
|
} else if (S_ISDIR(inode->i_mode)) {
|
|
inode->i_op = de->proc_iops;
|
|
inode->i_fop = de->proc_dir_ops;
|
|
} else if (S_ISLNK(inode->i_mode)) {
|
|
inode->i_op = de->proc_iops;
|
|
inode->i_fop = NULL;
|
|
} else
|
|
BUG();
|
|
} else
|
|
pde_put(de);
|
|
return inode;
|
|
}
|