[linux-block.git] / samples / kfifo / record-example.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Sample dynamic sized record fifo implementation
 *
 * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
 */

#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 variable sized record fifo.
 */

/* fifo size in elements (bytes) */
#define FIFO_SIZE	128

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

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

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

/*
 * 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

/*
 * struct kfifo_rec_ptr_1 and  STRUCT_KFIFO_REC_1 can handle records of a
 * length between 0 and 255 bytes.
 *
 * struct kfifo_rec_ptr_2 and  STRUCT_KFIFO_REC_2 can handle records of a
 * length between 0 and 65535 bytes.
 */

#ifdef DYNAMIC
struct kfifo_rec_ptr_1 test;

#else
typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest;

static mytest test;
#endif

static const char *expected_result[] = {
	"a",
	"bb",
	"ccc",
	"dddd",
	"eeeee",
	"ffffff",
	"ggggggg",
	"hhhhhhhh",
	"iiiiiiiii",
	"jjjjjjjjjj",
};

static int __init testfunc(void)
{
	char		buf[100];
	unsigned int	i;
	unsigned int	ret;
	struct { unsigned char buf[6]; } hello = { "hello" };

	printk(KERN_INFO "record fifo test start\n");

	kfifo_in(&test, &hello, sizeof(hello));

	/* show the size of the next record in the fifo */
	printk(KERN_INFO "fifo peek len: %u\n", kfifo_peek_len(&test));

	/* put in variable length data */
	for (i = 0; i < 10; i++) {
		memset(buf, 'a' + i, i + 1);
		kfifo_in(&test, buf, i + 1);
	}

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

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

	/* show the first record without removing from the fifo */
	ret = kfifo_out_peek(&test, buf, sizeof(buf));
	if (ret)
		printk(KERN_INFO "%.*s\n", ret, buf);

	/* check the correctness of all values in the fifo */
	i = 0;
	while (!kfifo_is_empty(&test)) {
		ret = kfifo_out(&test, buf, sizeof(buf));
		buf[ret] = '\0';
		printk(KERN_INFO "item = %.*s\n", ret, buf);
		if (strcmp(buf, expected_result[i++])) {
			printk(KERN_WARNING "value mismatch: test failed\n");
			return -EIO;
		}
	}
	if (i != 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_access))
		return -ERESTARTSYS;

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

	mutex_unlock(&write_access);
	if (ret)
		return ret;

	return 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_access))
		return -ERESTARTSYS;

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

	mutex_unlock(&read_access);
	if (ret)
		return ret;

	return copied;
}

static const struct proc_ops fifo_proc_ops = {
	.proc_read	= fifo_read,
	.proc_write	= fifo_write,
	.proc_lseek	= noop_llseek,
};

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_proc_ops) == 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
912d0f0b	1	// SPDX-License-Identifier: GPL-2.0-only
5bf2b193 SS	2	/*
	3	* Sample dynamic sized record fifo implementation
	4	*
	5	* Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
5bf2b193 SS	6	*/
	7
	8	#include <linux/init.h>
	9	#include <linux/module.h>
	10	#include <linux/proc_fs.h>
	11	#include <linux/mutex.h>
	12	#include <linux/kfifo.h>
	13
	14	/*
	15	* This module shows how to create a variable sized record fifo.
	16	*/
	17
	18	/* fifo size in elements (bytes) */
	19	#define FIFO_SIZE 128
	20
	21	/* name of the proc entry */
	22	#define PROC_FIFO "record-fifo"
	23
	24	/* lock for procfs read access */
880732ae	25	static DEFINE_MUTEX(read_access);
5bf2b193 SS	26
5bf2b193 SS	27	/* lock for procfs write access */
880732ae	28	static DEFINE_MUTEX(write_access);
5bf2b193 SS	29
	30	/*
	31	* define DYNAMIC in this example for a dynamically allocated fifo.
	32	*
	33	* Otherwise the fifo storage will be a part of the fifo structure.
	34	*/
	35	#if 0
	36	#define DYNAMIC
	37	#endif
	38
	39	/*
	40	* struct kfifo_rec_ptr_1 and STRUCT_KFIFO_REC_1 can handle records of a
	41	* length between 0 and 255 bytes.
	42	*
	43	* struct kfifo_rec_ptr_2 and STRUCT_KFIFO_REC_2 can handle records of a
	44	* length between 0 and 65535 bytes.
	45	*/
	46
	47	#ifdef DYNAMIC
	48	struct kfifo_rec_ptr_1 test;
	49
	50	#else
	51	typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest;
	52
	53	static mytest test;
	54	#endif
	55
a25effa4 AR	56	static const char *expected_result[] = {
	57	"a",
	58	"bb",
	59	"ccc",
	60	"dddd",
	61	"eeeee",
	62	"ffffff",
	63	"ggggggg",
	64	"hhhhhhhh",
	65	"iiiiiiiii",
	66	"jjjjjjjjjj",
	67	};
	68
5bf2b193 SS	69	static int __init testfunc(void)
	70	{
	71	char buf[100];
	72	unsigned int i;
	73	unsigned int ret;
	74	struct { unsigned char buf[6]; } hello = { "hello" };
	75
	76	printk(KERN_INFO "record fifo test start\n");
	77
	78	kfifo_in(&test, &hello, sizeof(hello));
	79
	80	/* show the size of the next record in the fifo */
	81	printk(KERN_INFO "fifo peek len: %u\n", kfifo_peek_len(&test));
	82
	83	/* put in variable length data */
	84	for (i = 0; i < 10; i++) {
	85	memset(buf, 'a' + i, i + 1);
	86	kfifo_in(&test, buf, i + 1);
	87	}
	88
a25effa4 AR	89	/* skip first element of the fifo */
	90	printk(KERN_INFO "skip 1st element\n");
	91	kfifo_skip(&test);
	92
5bf2b193 SS	93	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
	94
	95	/* show the first record without removing from the fifo */
	96	ret = kfifo_out_peek(&test, buf, sizeof(buf));
	97	if (ret)
	98	printk(KERN_INFO "%.*s\n", ret, buf);
	99
a25effa4 AR	100	/* check the correctness of all values in the fifo */
a25effa4 AR	101	i = 0;
5bf2b193 SS	102	while (!kfifo_is_empty(&test)) {
5bf2b193 SS	103	ret = kfifo_out(&test, buf, sizeof(buf));
a25effa4 AR	104	buf[ret] = '\0';
	105	printk(KERN_INFO "item = %.*s\n", ret, buf);
	106	if (strcmp(buf, expected_result[i++])) {
	107	printk(KERN_WARNING "value mismatch: test failed\n");
	108	return -EIO;
	109	}
	110	}
	111	if (i != ARRAY_SIZE(expected_result)) {
	112	printk(KERN_WARNING "size mismatch: test failed\n");
	113	return -EIO;
5bf2b193	114	}
a25effa4	115	printk(KERN_INFO "test passed\n");
5bf2b193 SS	116
	117	return 0;
	118	}
	119
	120	static ssize_t fifo_write(struct file file, const char __user buf,
	121	size_t count, loff_t *ppos)
	122	{
	123	int ret;
	124	unsigned int copied;
	125
880732ae	126	if (mutex_lock_interruptible(&write_access))
5bf2b193 SS	127	return -ERESTARTSYS;
	128
	129	ret = kfifo_from_user(&test, buf, count, &copied);
	130
880732ae	131	mutex_unlock(&write_access);
926ee00e DC	132	if (ret)
926ee00e DC	133	return ret;
5bf2b193	134
926ee00e	135	return copied;
5bf2b193 SS	136	}
	137
	138	static ssize_t fifo_read(struct file file, char __user buf,
	139	size_t count, loff_t *ppos)
	140	{
	141	int ret;
	142	unsigned int copied;
	143
880732ae	144	if (mutex_lock_interruptible(&read_access))
5bf2b193 SS	145	return -ERESTARTSYS;
	146
	147	ret = kfifo_to_user(&test, buf, count, &copied);
	148
880732ae	149	mutex_unlock(&read_access);
926ee00e DC	150	if (ret)
926ee00e DC	151	return ret;
5bf2b193	152
926ee00e	153	return copied;
5bf2b193 SS	154	}
5bf2b193 SS	155
97a32539 AD	156	static const struct proc_ops fifo_proc_ops = {
	157	.proc_read = fifo_read,
	158	.proc_write = fifo_write,
	159	.proc_lseek = noop_llseek,
5bf2b193 SS	160	};
	161
	162	static int __init example_init(void)
	163	{
	164	#ifdef DYNAMIC
	165	int ret;
	166
	167	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
	168	if (ret) {
	169	printk(KERN_ERR "error kfifo_alloc\n");
	170	return ret;
	171	}
	172	#else
	173	INIT_KFIFO(test);
	174	#endif
a25effa4 AR	175	if (testfunc() < 0) {
	176	#ifdef DYNAMIC
	177	kfifo_free(&test);
	178	#endif
	179	return -EIO;
	180	}
5bf2b193	181
97a32539	182	if (proc_create(PROC_FIFO, 0, NULL, &fifo_proc_ops) == NULL) {
5bf2b193 SS	183	#ifdef DYNAMIC
	184	kfifo_free(&test);
	185	#endif
	186	return -ENOMEM;
	187	}
	188	return 0;
	189	}
	190
	191	static void __exit example_exit(void)
	192	{
	193	remove_proc_entry(PROC_FIFO, NULL);
	194	#ifdef DYNAMIC
	195	kfifo_free(&test);
	196	#endif
	197	}
	198
	199	module_init(example_init);
	200	module_exit(example_exit);
	201	MODULE_LICENSE("GPL");
	202	MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");