Prev: [PATCH 3/4] replace the old non generic API
Next: [PATCH 0/4] enhanced reimplemention of the kfifo API
From: stefani on 10 Aug 2010 02:50
From: Stefani Seibold <stefani(a)seibold.net>

This patch 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

Signed-off-by: Stefani Seibold <stefani(a)seibold.net>
---
samples/Kconfig | 10 ++
samples/Makefile | 2 +-
samples/kfifo/Makefile | 1 +
samples/kfifo/bytestream-example.c | 163 +++++++++++++++++++++++++++++++++++
samples/kfifo/dma-example.c | 115 +++++++++++++++++++++++++
samples/kfifo/inttype-example.c | 157 +++++++++++++++++++++++++++++++++
samples/kfifo/record-example.c | 167 ++++++++++++++++++++++++++++++++++++
7 files changed, 614 insertions(+), 1 deletions(-)
create mode 100644 samples/kfifo/Makefile
create mode 100644 samples/kfifo/bytestream-example.c
create mode 100644 samples/kfifo/dma-example.c
create mode 100644 samples/kfifo/inttype-example.c
create mode 100644 samples/kfifo/record-example.c

diff --git a/samples/Kconfig b/samples/Kconfig
index 8924f72..954a1d5 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -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
diff --git a/samples/Makefile b/samples/Makefile
index 0f15e6d..76b3c34 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -1,4 +1,4 @@
# Makefile for Linux samples code

obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ tracepoints/ trace_events/ \
- hw_breakpoint/
+ hw_breakpoint/ kfifo/
diff --git a/samples/kfifo/Makefile b/samples/kfifo/Makefile
new file mode 100644
index 0000000..bcc9484
--- /dev/null
+++ b/samples/kfifo/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_SAMPLE_KFIFO) += bytestream-example.o dma-example.o inttype-example.o record-example.o
diff --git a/samples/kfifo/bytestream-example.c b/samples/kfifo/bytestream-example.c
new file mode 100644
index 0000000..642eef3
--- /dev/null
+++ b/samples/kfifo/bytestream-example.c
@@ -0,0 +1,163 @@
+/*
+ * Sample kfifo byte stream implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani(a)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(a)seibold.net>");
diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c
new file mode 100644
index 0000000..4ef4749
--- /dev/null
+++ b/samples/kfifo/dma-example.c
@@ -0,0 +1,115 @@
+/*
+ * Sample fifo dma implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani(a)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(a)seibold.net>");
diff --git a/samples/kfifo/inttype-example.c b/samples/kfifo/inttype-example.c
new file mode 100644
index 0000000..d6c5b7d
--- /dev/null
+++ b/samples/kfifo/inttype-example.c
@@ -0,0 +1,157 @@
+/*
+ * Sample kfifo int type implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani(a)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(a)seibold.net>");
diff --git a/samples/kfifo/record-example.c b/samples/kfifo/record-example.c
new file mode 100644
index 0000000..32c6e0b
--- /dev/null
+++ b/samples/kfifo/record-example.c
@@ -0,0 +1,167 @@
+/*
+ * Sample dynamic sized record fifo implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani(a)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(a)seibold.net>");
--
1.7.2

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