187 lines
3.8 KiB
C
187 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* Sample kfifo int type 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 int type fifo.
|
|
*/
|
|
|
|
/* fifo size in elements (ints) */
|
|
#define FIFO_SIZE 32
|
|
|
|
/* name of the proc entry */
|
|
#define PROC_FIFO "int-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
|
|
|
|
#ifdef DYNAMIC
|
|
static DECLARE_KFIFO_PTR(test, int);
|
|
#else
|
|
static DEFINE_KFIFO(test, int, FIFO_SIZE);
|
|
#endif
|
|
|
|
static const int 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)
|
|
{
|
|
int buf[6];
|
|
int i, j;
|
|
unsigned int ret;
|
|
|
|
printk(KERN_INFO "int fifo test start\n");
|
|
|
|
/* 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 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_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;
|
|
}
|
|
#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>");
|