内核模块编程-proc

The Linux Kernel Module Programming Guide中，
讲/proc的那一章节的源代码编译没有问题，insmod时，提示：
procfs.o: unresolved symbol proc_register
procfs.o: unresolved symbol proc_unregister
最后google了一下，最后发现新的内核没export出这两个接口，
使用create_proc_entry()和remove_proc_entry()就ok了。

修改代码之后编译时，总报错：
couldn't find the kernel version the module was compiled for
查看源代码，添加了
#include linux/module.h
#include linux/version.h
问题就解决了。
代码如下：

#include
#include
#include
#include
#include
#include

/* Deal with CONFIG_MODVERSIONS */
#if CONFIG_MODVERSIONS==1
#define MODVERSIONS
#include
#endif

/* In 2.2.3 /usr/include/linux/version.h includes a
 * macro for this, but 2.0.35 doesn't - so I add it
 * here if necessary. */
#ifndef KERNEL_VERSION
#define KERNEL_VERSION(a,b,c) ((a)*65536+(b)*256+(c))
#endif

#define MY_PROC_ENTRY_NAME "my_proc_entry"
struct proc_dir_entry *my_proc_entry=NULL;

static ssize_t ip_prof_output(
             struct file *file,
             char *buf,
             size_t len,
             loff_t *offset)
{
/* ... implement output from proc entry here ... */
return 0; /* returns number of output bytes */
}
static ssize_t ip_prof_input(
               struct file *file,
               const char *buf,
               size_t len,
               loff_t *offset)
{
/* ... implemetnt input into proc entry here ... */
return 0; /* returns number of input bytes */
}

int my_proc_entry_open(struct inode *inode, struct file *file) {
  return 0;
}

int my_proc_entry_close(struct inode *inode, struct file *file){
  return 0;
}

static int my_proc_entry_permission( struct inode *inode, int op) {
/* allow supeuser access only. doesn't really matter. */
  if(op==4 || (op==2 && current->euid==0))
    return 0;
  return -EACCES;
}

static struct file_operations my_proc_entry_fops =
{
        read: ip_prof_output,
        write: ip_prof_input,
        open: my_proc_entry_open,
        release:my_proc_entry_close,
};


static struct inode_operations my_proc_entry_iops =
{
       permission: my_proc_entry_permission
};

int start_my_proc_entry(void) {
  my_proc_entry = create_proc_entry(MY_PROC_ENTRY_NAME, S_IFREG | S_IRUGO | S_IWUSR, &proc_root);
  if ( !my_proc_entry ) return -ENOMEM;
  my_proc_entry->proc_fops = &my_proc_entry_fops;
  my_proc_entry->proc_iops = &my_proc_entry_iops;
  return 0;
}

int stop_my_proc_entry(void) {
  printk("my_proc_entry: terminating. ");
  remove_proc_entry(MY_PROC_ENTRY_NAME, &proc_root);
  return 0;
}

module_init(start_my_proc_entry);
module_exit(stop_my_proc_entry);