![Alexey Dobriyan](/assets/img/avatar_default.png)
WARN_ON(de && de->deleted); is sooo unreliable. Why? proc_lookup remove_proc_entry =========== ================= lock_kernel(); spin_lock(&proc_subdir_lock); [find proc entry] spin_unlock(&proc_subdir_lock); spin_lock(&proc_subdir_lock); [find proc entry] proc_get_inode ============== WARN_ON(de && de->deleted); ... if (!atomic_read(&de->count)) free_proc_entry(de); else de->deleted = 1; So, if you have some strange oops [1], and doesn't see this WARN_ON it means nothing. [1] try_module_get() of module which doesn't exist, two lines below should suffice, or not? Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
212 lines
4.3 KiB
C
212 lines
4.3 KiB
C
/*
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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/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/mm.h>
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#include <linux/string.h>
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#include <linux/stat.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/smp_lock.h>
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#include <asm/system.h>
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#include <asm/uaccess.h>
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#include "internal.h"
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struct proc_dir_entry *de_get(struct proc_dir_entry *de)
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{
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if (de)
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atomic_inc(&de->count);
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return de;
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}
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/*
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* Decrements the use count and checks for deferred deletion.
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*/
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void de_put(struct proc_dir_entry *de)
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{
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if (de) {
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lock_kernel();
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if (!atomic_read(&de->count)) {
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printk("de_put: entry %s already free!\n", de->name);
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unlock_kernel();
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return;
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}
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if (atomic_dec_and_test(&de->count)) {
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if (de->deleted) {
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printk("de_put: deferred delete of %s\n",
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de->name);
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free_proc_entry(de);
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}
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}
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unlock_kernel();
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}
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}
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/*
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* Decrement the use count of the proc_dir_entry.
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*/
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static void proc_delete_inode(struct inode *inode)
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{
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struct proc_dir_entry *de;
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truncate_inode_pages(&inode->i_data, 0);
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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 = PROC_I(inode)->pde;
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if (de) {
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if (de->owner)
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module_put(de->owner);
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de_put(de);
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}
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clear_inode(inode);
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}
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struct vfsmount *proc_mnt;
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static void proc_read_inode(struct inode * inode)
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{
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inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
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}
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static struct kmem_cache * proc_inode_cachep;
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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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struct inode *inode;
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ei = (struct proc_inode *)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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inode = &ei->vfs_inode;
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inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
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return inode;
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}
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static void proc_destroy_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, struct kmem_cache * cachep, unsigned long flags)
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{
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struct proc_inode *ei = (struct proc_inode *) foo;
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if (flags & SLAB_CTOR_CONSTRUCTOR)
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inode_init_once(&ei->vfs_inode);
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}
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int __init proc_init_inodecache(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),
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init_once, NULL);
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if (proc_inode_cachep == NULL)
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return -ENOMEM;
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return 0;
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}
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static int proc_remount(struct super_block *sb, int *flags, char *data)
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{
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*flags |= MS_NODIRATIME;
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return 0;
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}
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static const struct super_operations proc_sops = {
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.alloc_inode = proc_alloc_inode,
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.destroy_inode = proc_destroy_inode,
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.read_inode = proc_read_inode,
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.drop_inode = generic_delete_inode,
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.delete_inode = proc_delete_inode,
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.statfs = simple_statfs,
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.remount_fs = proc_remount,
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};
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struct inode *proc_get_inode(struct super_block *sb, unsigned int ino,
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struct proc_dir_entry *de)
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{
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struct inode * inode;
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if (de != NULL && !try_module_get(de->owner))
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goto out_mod;
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inode = iget(sb, ino);
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if (!inode)
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goto out_ino;
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PROC_I(inode)->fd = 0;
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PROC_I(inode)->pde = de;
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if (de) {
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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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inode->i_nlink = de->nlink;
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if (de->proc_iops)
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inode->i_op = de->proc_iops;
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if (de->proc_fops)
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inode->i_fop = de->proc_fops;
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}
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return inode;
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out_ino:
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if (de != NULL)
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module_put(de->owner);
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out_mod:
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return NULL;
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}
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int proc_fill_super(struct super_block *s, void *data, int silent)
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{
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struct inode * root_inode;
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s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC;
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s->s_blocksize = 1024;
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s->s_blocksize_bits = 10;
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s->s_magic = PROC_SUPER_MAGIC;
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s->s_op = &proc_sops;
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s->s_time_gran = 1;
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de_get(&proc_root);
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root_inode = proc_get_inode(s, PROC_ROOT_INO, &proc_root);
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if (!root_inode)
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goto out_no_root;
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root_inode->i_uid = 0;
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root_inode->i_gid = 0;
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s->s_root = d_alloc_root(root_inode);
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if (!s->s_root)
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goto out_no_root;
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return 0;
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out_no_root:
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printk("proc_read_super: get root inode failed\n");
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iput(root_inode);
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de_put(&proc_root);
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return -ENOMEM;
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}
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MODULE_LICENSE("GPL");
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