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authorStefani Seibold <stefani@seibold.net>2010-08-10 18:03:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-08-11 08:59:23 -0700
commit5bf2b19320ec31d094d7370fdf536f7fd91fd799 (patch)
tree47052fd9bdb0969d4a4a7d430695388094409964 /samples/kfifo/inttype-example.c
parent2e956fb320568cc70861761483e2f0e2db75fd66 (diff)
downloadleg-kernel-5bf2b19320ec31d094d7370fdf536f7fd91fd799.tar.gz
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: Stefani Seibold <stefani@seibold.net> Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'samples/kfifo/inttype-example.c')
-rw-r--r--samples/kfifo/inttype-example.c157
1 files changed, 157 insertions, 0 deletions
diff --git a/samples/kfifo/inttype-example.c b/samples/kfifo/inttype-example.c
new file mode 100644
index 000000000000..d6c5b7d9df64
--- /dev/null
+++ b/samples/kfifo/inttype-example.c
@@ -0,0 +1,157 @@
+/*
+ * 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>");