From 504db8a2bae95d7bafb9b68074fdc46c49f08c9f Mon Sep 17 00:00:00 2001
From: Manuel Traut <manut@linutronix.de>
Date: Fri, 4 Jan 2019 09:32:18 +0100
Subject: [PATCH] klist example

this can be used to show the usage of klists

Signed-off-by: Manuel Traut <manut@linutronix.de>
---
 drivers/staging/Kconfig         |  2 +
 drivers/staging/Makefile        |  1 +
 drivers/staging/klist/Kconfig  |  5 +++
 drivers/staging/klist/Makefile |  1 +
 drivers/staging/klist/klist.c | 68 +++++++++++++++++++++++++++++++++
 5 files changed, 77 insertions(+)
 create mode 100644 drivers/staging/klist/Kconfig
 create mode 100644 drivers/staging/klist/Makefile
 create mode 100644 drivers/staging/klist/klist.c

diff --git a/drivers/staging/Kconfig b/drivers/staging/Kconfig
index bfa2bf720a03..98541d7a41be 100644
--- a/drivers/staging/Kconfig
+++ b/drivers/staging/Kconfig
@@ -24,6 +24,8 @@ menuconfig STAGING
 
 if STAGING
 
+source "drivers/staging/klist/Kconfig"
+
 source "drivers/staging/wlan-ng/Kconfig"
 
 source "drivers/staging/comedi/Kconfig"
diff --git a/drivers/staging/Makefile b/drivers/staging/Makefile
index 25b3a8eafaa1..7a6d82750008 100644
--- a/drivers/staging/Makefile
+++ b/drivers/staging/Makefile
@@ -2,6 +2,7 @@
 # Makefile for staging directory
 
 obj-y				+= media/
+obj-$(CONFIG_KLISTEXAMPLE)		+= klist/
 obj-$(CONFIG_PRISM2_USB)	+= wlan-ng/
 obj-$(CONFIG_COMEDI)		+= comedi/
 obj-$(CONFIG_FB_OLPC_DCON)	+= olpc_dcon/
diff --git a/drivers/staging/klist/Kconfig b/drivers/staging/klist/Kconfig
new file mode 100644
index 000000000000..18f517e56cb9
--- /dev/null
+++ b/drivers/staging/klist/Kconfig
@@ -0,0 +1,4 @@
+config KLISTEXAMPLE
+	tristate "module to teach klist usage"
+	---help---
+	  This is only useful for learning the usage of klist.
diff --git a/drivers/staging/klist/Makefile b/drivers/staging/klist/Makefile
new file mode 100644
index 000000000000..2939c11d72ff
--- /dev/null
+++ b/drivers/staging/klist/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_KLISTEXAMPLE)		+= klist.o
diff --git a/drivers/staging/klist/klist.c b/drivers/staging/klist/klist.c
new file mode 100644
index 000000000000..365acaa3263a
--- /dev/null
+++ b/drivers/staging/klist/klist.c
@@ -0,0 +1,68 @@
+/*
+ * Example driver for using klist
+ * Copyright (C) 2019, Manuel Traut <manut@linutronix.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+
+#define DRV_NAME "klist"
+
+struct mynode {
+	struct list_head node;
+	unsigned long val;
+};
+
+static struct list_head mylist;
+static char mystring[] = "1 2 3 4 5\n";
+
+static void klist_free_list(void) {
+	struct mynode *n, *tmp;
+	list_for_each_entry_safe(n, tmp, &mylist, node)
+		kfree(n);
+}
+
+static void klist_init_list(void) {
+	unsigned long val;
+	struct mynode *n;
+	char *tok;
+	char *b = kstrdup(mystring, GFP_KERNEL);
+
+	INIT_LIST_HEAD(&mylist);
+
+	while ((tok = strsep(&b, " ")) && *tok) {
+		printk(KERN_INFO "adding %s to list\n", tok);
+		if (kstrtoul(tok, 0, &val)) {
+			printk(KERN_ERR "failed to convert %s to int\n", tok);
+			goto exit_init;
+		}
+		n = kzalloc(sizeof(*n), GFP_KERNEL);
+		n->val = val;
+		list_add_tail(&n->node, &mylist);
+	}
+exit_init:
+	kfree(b);
+}
+
+static int __init klist_init(void) {
+	printk(KERN_INFO "%s\n", __func__);
+	klist_init_list();
+	return 0;
+}
+
+static void __exit klist_exit(void) {
+	printk(KERN_INFO "%s\n", __func__);
+	klist_free_list();
+}
+
+module_init(klist_init);
+module_exit(klist_exit);
+MODULE_AUTHOR("Manuel Traut");
+MODULE_LICENSE("GPL");
-- 
2.19.2