[net-next-2.6.git] / samples / kfifo / bytestream-example.c

/*
 * Sample kfifo byte stream implementation
 *
 * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
 *
 * Released under the GPL version 2 only.
 *
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/mutex.h>
#include <linux/kfifo.h>

/*
 * This module shows how to create a byte stream fifo.
 */

/* fifo size in elements (bytes) */
#define FIFO_SIZE	32

/* name of the proc entry */
#define	PROC_FIFO	"bytestream-fifo"

/* lock for procfs read access */
static DEFINE_MUTEX(read_lock);

/* lock for procfs write access */
static DEFINE_MUTEX(write_lock);

/*
 * define DYNAMIC in this example for a dynamically allocated fifo.
 *
 * Otherwise the fifo storage will be a part of the fifo structure.
 */
#if 0
#define DYNAMIC
#endif

#ifdef DYNAMIC
static struct kfifo test;
#else
static DECLARE_KFIFO(test, unsigned char, FIFO_SIZE);
#endif

static const unsigned char expected_result[FIFO_SIZE] = {
	 3,  4,  5,  6,  7,  8,  9,  0,
	 1, 20, 21, 22, 23, 24, 25, 26,
	27, 28, 29, 30, 31, 32, 33, 34,
	35, 36, 37, 38, 39, 40, 41, 42,
};

static int __init testfunc(void)
{
	unsigned char	buf[6];
	unsigned char	i, j;
	unsigned int	ret;

	printk(KERN_INFO "byte stream fifo test start\n");

	/* put string into the fifo */
	kfifo_in(&test, "hello", 5);

	/* put values into the fifo */
	for (i = 0; i != 10; i++)
		kfifo_put(&test, &i);

	/* show the number of used elements */
	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));

	/* get max of 5 bytes from the fifo */
	i = kfifo_out(&test, buf, 5);
	printk(KERN_INFO "buf: %.*s\n", i, buf);

	/* get max of 2 elements from the fifo */
	ret = kfifo_out(&test, buf, 2);
	printk(KERN_INFO "ret: %d\n", ret);
	/* and put it back to the end of the fifo */
	ret = kfifo_in(&test, buf, ret);
	printk(KERN_INFO "ret: %d\n", ret);

	/* skip first element of the fifo */
	printk(KERN_INFO "skip 1st element\n");
	kfifo_skip(&test);

	/* put values into the fifo until is full */
	for (i = 20; kfifo_put(&test, &i); i++)
		;

	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));

	/* show the first value without removing from the fifo */
	if (kfifo_peek(&test, &i))
		printk(KERN_INFO "%d\n", i);

	/* check the correctness of all values in the fifo */
	j = 0;
	while (kfifo_get(&test, &i)) {
		printk(KERN_INFO "item = %d\n", i);
		if (i != expected_result[j++]) {
			printk(KERN_WARNING "value mismatch: test failed\n");
			return -EIO;
		}
	}
	if (j != ARRAY_SIZE(expected_result)) {
		printk(KERN_WARNING "size mismatch: test failed\n");
		return -EIO;
	}
	printk(KERN_INFO "test passed\n");

	return 0;
}

static ssize_t fifo_write(struct file *file, const char __user *buf,
						size_t count, loff_t *ppos)
{
	int ret;
	unsigned int copied;

	if (mutex_lock_interruptible(&write_lock))
		return -ERESTARTSYS;

	ret = kfifo_from_user(&test, buf, count, &copied);

	mutex_unlock(&write_lock);

	return ret ? ret : copied;
}

static ssize_t fifo_read(struct file *file, char __user *buf,
						size_t count, loff_t *ppos)
{
	int ret;
	unsigned int copied;

	if (mutex_lock_interruptible(&read_lock))
		return -ERESTARTSYS;

	ret = kfifo_to_user(&test, buf, count, &copied);

	mutex_unlock(&read_lock);

	return ret ? ret : copied;
}

static const struct file_operations fifo_fops = {
	.owner		= THIS_MODULE,
	.read		= fifo_read,
	.write		= fifo_write,
};

static int __init example_init(void)
{
#ifdef DYNAMIC
	int ret;

	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
	if (ret) {
		printk(KERN_ERR "error kfifo_alloc\n");
		return ret;
	}
#else
	INIT_KFIFO(test);
#endif
	if (testfunc() < 0) {
#ifdef DYNAMIC
		kfifo_free(&test);
#endif
		return -EIO;
	}

	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
#ifdef DYNAMIC
		kfifo_free(&test);
#endif
		return -ENOMEM;
	}
	return 0;
}

static void __exit example_exit(void)
{
	remove_proc_entry(PROC_FIFO, NULL);
#ifdef DYNAMIC
	kfifo_free(&test);
#endif
}

module_init(example_init);
module_exit(example_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
Commit	Line	Data
	1	/*
	2	* Sample kfifo byte stream implementation
	3	*
	4	* Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
	5	*
	6	* Released under the GPL version 2 only.
	7	*
	8	*/
	9
	10	#include <linux/init.h>
	11	#include <linux/module.h>
	12	#include <linux/proc_fs.h>
	13	#include <linux/mutex.h>
	14	#include <linux/kfifo.h>
	15
	16	/*
	17	* This module shows how to create a byte stream fifo.
	18	*/
	19
	20	/* fifo size in elements (bytes) */
	21	#define FIFO_SIZE 32
	22
	23	/* name of the proc entry */
	24	#define PROC_FIFO "bytestream-fifo"
	25
	26	/* lock for procfs read access */
	27	static DEFINE_MUTEX(read_lock);
	28
	29	/* lock for procfs write access */
	30	static DEFINE_MUTEX(write_lock);
	31
	32	/*
	33	* define DYNAMIC in this example for a dynamically allocated fifo.
	34	*
	35	* Otherwise the fifo storage will be a part of the fifo structure.
	36	*/
	37	#if 0
	38	#define DYNAMIC
	39	#endif
	40
	41	#ifdef DYNAMIC
	42	static struct kfifo test;
	43	#else
	44	static DECLARE_KFIFO(test, unsigned char, FIFO_SIZE);
	45	#endif
	46
	47	static const unsigned char expected_result[FIFO_SIZE] = {
	48	3, 4, 5, 6, 7, 8, 9, 0,
	49	1, 20, 21, 22, 23, 24, 25, 26,
	50	27, 28, 29, 30, 31, 32, 33, 34,
	51	35, 36, 37, 38, 39, 40, 41, 42,
	52	};
	53
	54	static int __init testfunc(void)
	55	{
	56	unsigned char buf[6];
	57	unsigned char i, j;
	58	unsigned int ret;
	59
	60	printk(KERN_INFO "byte stream fifo test start\n");
	61
	62	/* put string into the fifo */
	63	kfifo_in(&test, "hello", 5);
	64
	65	/* put values into the fifo */
	66	for (i = 0; i != 10; i++)
	67	kfifo_put(&test, &i);
	68
	69	/* show the number of used elements */
	70	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
	71
	72	/* get max of 5 bytes from the fifo */
	73	i = kfifo_out(&test, buf, 5);
	74	printk(KERN_INFO "buf: %.*s\n", i, buf);
	75
	76	/* get max of 2 elements from the fifo */
	77	ret = kfifo_out(&test, buf, 2);
	78	printk(KERN_INFO "ret: %d\n", ret);
	79	/* and put it back to the end of the fifo */
	80	ret = kfifo_in(&test, buf, ret);
	81	printk(KERN_INFO "ret: %d\n", ret);
	82
	83	/* skip first element of the fifo */
	84	printk(KERN_INFO "skip 1st element\n");
	85	kfifo_skip(&test);
	86
	87	/* put values into the fifo until is full */
	88	for (i = 20; kfifo_put(&test, &i); i++)
	89	;
	90
	91	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
	92
	93	/* show the first value without removing from the fifo */
	94	if (kfifo_peek(&test, &i))
	95	printk(KERN_INFO "%d\n", i);
	96
	97	/* check the correctness of all values in the fifo */
	98	j = 0;
	99	while (kfifo_get(&test, &i)) {
	100	printk(KERN_INFO "item = %d\n", i);
	101	if (i != expected_result[j++]) {
	102	printk(KERN_WARNING "value mismatch: test failed\n");
	103	return -EIO;
	104	}
	105	}
	106	if (j != ARRAY_SIZE(expected_result)) {
	107	printk(KERN_WARNING "size mismatch: test failed\n");
	108	return -EIO;
	109	}
	110	printk(KERN_INFO "test passed\n");
	111
	112	return 0;
	113	}
	114
	115	static ssize_t fifo_write(struct file file, const char __user buf,
	116	size_t count, loff_t *ppos)
	117	{
	118	int ret;
	119	unsigned int copied;
	120
	121	if (mutex_lock_interruptible(&write_lock))
	122	return -ERESTARTSYS;
	123
	124	ret = kfifo_from_user(&test, buf, count, &copied);
	125
	126	mutex_unlock(&write_lock);
	127
	128	return ret ? ret : copied;
	129	}
	130
	131	static ssize_t fifo_read(struct file file, char __user buf,
	132	size_t count, loff_t *ppos)
	133	{
	134	int ret;
	135	unsigned int copied;
	136
	137	if (mutex_lock_interruptible(&read_lock))
	138	return -ERESTARTSYS;
	139
	140	ret = kfifo_to_user(&test, buf, count, &copied);
	141
	142	mutex_unlock(&read_lock);
	143
	144	return ret ? ret : copied;
	145	}
	146
	147	static const struct file_operations fifo_fops = {
	148	.owner = THIS_MODULE,
	149	.read = fifo_read,
	150	.write = fifo_write,
	151	};
	152
	153	static int __init example_init(void)
	154	{
	155	#ifdef DYNAMIC
	156	int ret;
	157
	158	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
	159	if (ret) {
	160	printk(KERN_ERR "error kfifo_alloc\n");
	161	return ret;
	162	}
	163	#else
	164	INIT_KFIFO(test);
	165	#endif
	166	if (testfunc() < 0) {
	167	#ifdef DYNAMIC
	168	kfifo_free(&test);
	169	#endif
	170	return -EIO;
	171	}
	172
	173	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
	174	#ifdef DYNAMIC
	175	kfifo_free(&test);
	176	#endif
	177	return -ENOMEM;
	178	}
	179	return 0;
	180	}
	181
	182	static void __exit example_exit(void)
	183	{
	184	remove_proc_entry(PROC_FIFO, NULL);
	185	#ifdef DYNAMIC
	186	kfifo_free(&test);
	187	#endif
	188	}
	189
	190	module_init(example_init);
	191	module_exit(example_exit);
	192	MODULE_LICENSE("GPL");
	193	MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");