Linux Cross Reference
Linux-2.6.17/net/nonet.c

   /*
    * net/nonet.c
    *
    * Dummy functions to allow us to configure network support entirely
    * out of the kernel.
    *
    * Distributed under the terms of the GNU GPL version 2.
    * Copyright (c) Matthew Wilcox 2003
    */
  
  #include <linux/module.h>
  #include <linux/errno.h>
  #include <linux/fs.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  
  static int sock_no_open(struct inode *irrelevant, struct file *dontcare)
  {
          return -ENXIO;
  }
  
  const struct file_operations bad_sock_fops = {
          .owner = THIS_MODULE,
          .open = sock_no_open,
  };