#define __NO_VERSION__
#include <linux/config.h>
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/personality.h>
#include <linux/smp_lock.h>
#include <linux/delay.h>

#define kdebug(FMT,...)
//#define kdebug printk

MODULE_AUTHOR("David Howells");
MODULE_DESCRIPTION("R/W semaphore test demo");


struct proc_dir_entry *rwsem_proc;

struct rw_semaphore rwsem_sem;

static int rwsem_read_proc(char *page, char **start, off_t off,
			   int count, int *eof, void *data)
{
	kdebug("[%d] r-downing: %08x\n",current->pid,rwsem_sem.count.counter);
	down_read(&rwsem_sem);
	kdebug("[%d] r-downed: %08x\n",current->pid,rwsem_sem.count.counter);
	mdelay(2);
	kdebug("[%d] r-upping: %08x\n",current->pid,rwsem_sem.count.counter);
	up_read(&rwsem_sem);
	kdebug("[%d] r-upped: %08x\n",current->pid,rwsem_sem.count.counter);

	return -ENOENT;
}

static int rwsem_write_proc(struct file *file, const char *buffer, unsigned long count, void *data)
{
	kdebug("[%d] w-downing: %08x\n",current->pid,rwsem_sem.count.counter);
	down_write(&rwsem_sem);
	kdebug("[%d] w-downed: %08x\n",current->pid,rwsem_sem.count.counter);
	mdelay(2);
	kdebug("[%d] w-upping: %08x\n",current->pid,rwsem_sem.count.counter);
	up_write(&rwsem_sem);
	kdebug("[%d] w-upped: %08x\n",current->pid,rwsem_sem.count.counter);

	return -ENOENT;
}

static int __init rwsem_init_module(void)
{
	kdebug(KERN_INFO "rwsem loading...\n");

	init_rwsem(&rwsem_sem);

	rwsem_proc = create_proc_entry("rwsem",S_IRUGO|S_IWUGO,NULL);
	if (!rwsem_proc)
		return -EEXIST;

	rwsem_proc->read_proc = &rwsem_read_proc;
	rwsem_proc->write_proc = &rwsem_write_proc;
	return 0;
}

static void __exit rwsem_cleanup_module(void)
{
	kdebug(KERN_INFO "rwsem unloading\n");

	remove_proc_entry("rwsem",NULL);

}

module_init(rwsem_init_module);
module_exit(rwsem_cleanup_module);