separate modules into hello1 and hello2

hello1 handles all required operations while hello2 triggers them at
load and unload

Makefile

@@ -1,7 +1,8 @@
 
 ifneq ($(KERNELRELEASE),)
 # kbuild part of makefile
-obj-m   := hello.o
+obj-m   := hello1.o hello2.o
+ccflags-y := -I$(obj)/inc
 else
 # normal makefile
 KDIR ?= /lib/modules/`uname -r`/build

hello1.c

@@ -40,48 +40,54 @@ MODULE_LICENSE("Dual BSD/GPL");
 
 struct TimingList {
 	struct TimingList *next;
-	ktime_t t;
+	ktime_t t_before;
+	ktime_t t_after;
 };
 
 static unsigned int msg_count = 1;
 static struct TimingList *tl_head;
 
-static void init_new_list(void)
+static struct TimingList* write_first_node(void)
 {
 	tl_head = kmalloc(sizeof(struct TimingList), GFP_KERNEL);
-
 	tl_head->next = NULL;
-	tl_head->t = ktime_get();
+
+	return tl_head;
 }
 
-static void insert_new_time(void)
+static struct TimingList* insert_next_node(struct TimingList *tail)
 {
-	struct TimingList *last_tl_node = tl_head;
 	struct TimingList *new_tl_node = kmalloc(sizeof(struct TimingList),
 						GFP_KERNEL);
 
-	while (last_tl_node->next != NULL)
+	tail->next = new_tl_node;
-		last_tl_node = last_tl_node->next;
-
-
 	new_tl_node->next = NULL;
-	new_tl_node->t = ktime_get();
 
-	last_tl_node->next = new_tl_node;
+	return new_tl_node;
 }
 
-static void print_time(ktime_t *t)
+static struct TimingList* add_new_node(struct TimingList *tail)
 {
-	printk(KERN_EMERG "%lld\n", *t);
+	if (tail == NULL)
+		return write_first_node();
+	else
+		return insert_next_node(tail);
 }
 
-static void destroy_list(void)
+static void print_time_diff(struct TimingList *node)
+{
+	printk(KERN_EMERG "%lld\n", node->t_after - node->t_before);
+}
+
+void destroy_list(void)
 {
 	struct TimingList *curr_tl = tl_head;
 	struct TimingList *next_tl = NULL;
 
+	tl_head = NULL;
+
 	while (curr_tl != NULL) {
-		print_time(&(curr_tl->t));
+		print_time_diff(curr_tl);
 
 		next_tl = curr_tl->next;
 		kfree(curr_tl);
@@ -89,18 +95,8 @@ static void destroy_list(void)
 	}
 }
 
-static void update_timing_list(void)
-{
-	if (tl_head == NULL)
-		init_new_list();
-	else
-		insert_new_time();
-}
-
 static int __init hello_init(void)
 {
-	int i;
-
 	if (msg_count > 10) {
 		printk(KERN_EMERG "Error: msg_count too large (%d > 10)\n",
 				msg_count);
@@ -112,15 +108,23 @@ static int __init hello_init(void)
 				msg_count);
 	}
 
-	for (i = 0; i < msg_count; i++) {
-		update_timing_list();
-
-		printk(KERN_EMERG "Hello, world!\n");
-	}
-
 	return 0;
 }
 
+void print_hello(void)
+{
+	int i;
+	struct TimingList *current_tail = tl_head;
+
+	for (i = 0; i < msg_count; i++) {
+		current_tail = add_new_node(current_tail);
+
+		current_tail->t_before = ktime_get();
+		printk(KERN_EMERG "Hello, world!\n");
+		current_tail->t_after = ktime_get();
+	}
+}
+
 static void __exit hello_exit(void)
 {
 	destroy_list();
@@ -129,5 +133,8 @@ static void __exit hello_exit(void)
 module_param(msg_count, uint, 0444);
 MODULE_PARM_DESC(msg_count, "Amount of hello world outputs on load");
 
+EXPORT_SYMBOL(print_hello);
+EXPORT_SYMBOL(destroy_list);
+
 module_init(hello_init);
 module_exit(hello_exit);

hello2.c

@@ -0,0 +1,55 @@
+
+/*
+ * Copyright (c) 2017, GlobalLogic Ukraine LLC
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *    This product includes software developed by the GlobalLogic.
+ * 4. Neither the name of the GlobalLogic nor the
+ *    names of its contributors may be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY GLOBALLOGIC UKRAINE LLC ``AS IS`` AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL GLOBALLOGIC UKRAINE LLC BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
+
+#include "hello1.h"
+
+MODULE_AUTHOR("Serhii Popovych <serhii.popovych@globallogic.com>");
+MODULE_DESCRIPTION("Hello, world in Linux Kernel Training");
+MODULE_LICENSE("Dual BSD/GPL");
+
+static int __init hello_init(void)
+{
+	print_hello();
+	return 0;
+}
+
+static void __exit hello_exit(void)
+{
+	destroy_list();
+}
+
+module_init(hello_init);
+module_exit(hello_exit);

inc/hello1.h

@@ -0,0 +1,2 @@
+void print_hello(void);
+void destroy_list(void);