Using seqfile

#include <linux/kernel.h>    /* We're doing kernel work */
#include <linux/module.h>    /* Specifically, a module */
#include <linux/proc_fs.h>    /* Necessary because we use proc fs */
#include <linux/seq_file.h>    /* for seq_file */
 
#define PROC_NAME    "iter"
 
int global=9;
 
MODULE_AUTHOR("Philippe Reynes");
MODULE_LICENSE("GPL");
 
/**
 * This function is called at the beginning of a sequence.
 * ie, when:
 *    - the /proc file is read (first time)
 *    - after the function stop (end of sequence)
 *
 */
static void *my_seq_start(struct seq_file *s, loff_t *pos)
{
    static unsigned long counter = 0;
 
    /* beginning a new sequence ? */    
    if ( *pos == 0 )
    {    
        /* yes => return a non null value to begin the sequence */
        return &counter;
    }
    else
    {
        /* no => it's the end of the sequence, return end to stop reading */
        *pos = 0;
        global++;
        return NULL;
    }
}
 
/**
 * This function is called after the beginning of a sequence.
 * It's called untill the return is NULL (this ends the sequence).
 *
 */
static void *my_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
    unsigned long *tmp_v = (unsigned long *)v;
    (*tmp_v)++;
    (*pos)++;
    return NULL;
}
 
/**
 * This function is called at the end of a sequence
 * 
 */
static void my_seq_stop(struct seq_file *s, void *v)
{
    /* nothing to do, we use a static value in start() */
}
 
/**
 * This function is called for each "step" of a sequence
 *
 */
static int my_seq_show(struct seq_file *s, void *v)
{
    loff_t *spos = (loff_t *) v;
 
    seq_printf(s, "%Ld\n", *spos);
    return 0;
}
 
/**
 * This structure gather "function" to manage the sequence
 *
 */
static struct seq_operations my_seq_ops = {
    .start = my_seq_start,
    .next  = my_seq_next,
    .stop  = my_seq_stop,
    .show  = my_seq_show
};
 
/**
 * This function is called when the /proc file is open.
 *
 */
static int my_open(struct inode *inode, struct file *file)
{
    return seq_open(file, &my_seq_ops);
};
 
/**
 * This structure gather "function" that manage the /proc file
 *
 */
static struct file_operations my_file_ops = {
    .owner   = THIS_MODULE,
    .open    = my_open,
    .read    = seq_read,
    .llseek  = seq_lseek,
    .release = seq_release
};
 
/**
 * This function is called when the module is loaded
 *
 */
int init_module(void)
{
    struct proc_dir_entry *entry;
 
    entry = create_proc_entry(PROC_NAME, 0, NULL);
    if (entry) {
        entry->proc_fops = &my_file_ops;
    }
 
    return 0;
}
 
/**
 * This function is called when the module is unloaded.
 *
 */
void cleanup_module(void)
{
    remove_proc_entry(PROC_NAME, NULL);
}