Commit 5bf2b193 authored by Stefani Seibold's avatar Stefani Seibold Committed by Linus Torvalds

kfifo: add example files to the kernel sample directory

Add four examples to the kernel sample directory.

It shows how to handle:
- a byte stream fifo
- a integer type fifo
- a dynamic record sized fifo
- the fifo DMA functions

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: 's avatarStefani Seibold <stefani@seibold.net>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: 's avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2e956fb3
......@@ -44,4 +44,14 @@ config SAMPLE_HW_BREAKPOINT
help
This builds kernel hardware breakpoint example modules.
config SAMPLE_KFIFO
tristate "Build kfifo examples -- loadable modules only"
depends on m
help
This config option will allow you to build a number of
different kfifo sample modules showing how to use the
generic kfifo API.
If in doubt, say "N" here.
endif # SAMPLES
# Makefile for Linux samples code
obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ tracepoints/ trace_events/ \
hw_breakpoint/
hw_breakpoint/ kfifo/
obj-$(CONFIG_SAMPLE_KFIFO) += bytestream-example.o dma-example.o inttype-example.o record-example.o
/*
* 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 int __init testfunc(void)
{
unsigned char buf[6];
unsigned char i;
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);
/* 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));
/* print out all values in the fifo */
while (kfifo_get(&test, &i))
printk("%d ", i);
printk("\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
testfunc();
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>");
/*
* Sample fifo dma 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/kfifo.h>
/*
* This module shows how to handle fifo dma operations.
*/
/* fifo size in elements (bytes) */
#define FIFO_SIZE 32
static struct kfifo fifo;
static int __init example_init(void)
{
int i;
unsigned int ret;
struct scatterlist sg[10];
printk(KERN_INFO "DMA fifo test start\n");
if (kfifo_alloc(&fifo, FIFO_SIZE, GFP_KERNEL)) {
printk(KERN_ERR "error kfifo_alloc\n");
return 1;
}
printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo));
kfifo_in(&fifo, "test", 4);
for (i = 0; i != 9; i++)
kfifo_put(&fifo, &i);
/* kick away first byte */
ret = kfifo_get(&fifo, &i);
printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
ret = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
printk(KERN_INFO "DMA sgl entries: %d\n", ret);
/* if 0 was returned, fifo is full and no sgl was created */
if (ret) {
printk(KERN_INFO "scatterlist for receive:\n");
for (i = 0; i < ARRAY_SIZE(sg); i++) {
printk(KERN_INFO
"sg[%d] -> "
"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
i, sg[i].page_link, sg[i].offset, sg[i].length);
if (sg_is_last(&sg[i]))
break;
}
/* but here your code to setup and exectute the dma operation */
/* ... */
/* example: zero bytes received */
ret = 0;
/* finish the dma operation and update the received data */
kfifo_dma_in_finish(&fifo, ret);
}
ret = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8);
printk(KERN_INFO "DMA sgl entries: %d\n", ret);
/* if 0 was returned, no data was available and no sgl was created */
if (ret) {
printk(KERN_INFO "scatterlist for transmit:\n");
for (i = 0; i < ARRAY_SIZE(sg); i++) {
printk(KERN_INFO
"sg[%d] -> "
"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
i, sg[i].page_link, sg[i].offset, sg[i].length);
if (sg_is_last(&sg[i]))
break;
}
/* but here your code to setup and exectute the dma operation */
/* ... */
/* example: 5 bytes transmitted */
ret = 5;
/* finish the dma operation and update the transmitted data */
kfifo_dma_out_finish(&fifo, ret);
}
printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
return 0;
}
static void __exit example_exit(void)
{
#ifdef DYNAMIC
kfifo_free(&test);
#endif
}
module_init(example_init);
module_exit(example_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
/*
* Sample kfifo int type 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 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_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 DECLARE_KFIFO_PTR(test, int);
#else
static DEFINE_KFIFO(test, int, FIFO_SIZE);
#endif
static int __init testfunc(void)
{
int buf[6];
int i;
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);
for (i = 20; i != 30; i++)
kfifo_put(&test, &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);
/* print out all values in the fifo */
while (kfifo_get(&test, &i))
printk("%d ", i);
printk("\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;
}
#endif
testfunc();
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>");
/*
* Sample dynamic sized record fifo 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 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_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
/*
* 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 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);
}
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);
/* print out all records in the fifo */
while (!kfifo_is_empty(&test)) {
ret = kfifo_out(&test, buf, sizeof(buf));
printk(KERN_INFO "%.*s\n", ret, buf);
}
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
testfunc();
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>");
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