Makefile

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

hello.c

@@ -40,54 +40,48 @@ MODULE_LICENSE("Dual BSD/GPL");
 
 struct TimingList {
 	struct TimingList *next;
-	ktime_t t_before;
+	ktime_t t;
-	ktime_t t_after;
 };
 
 static unsigned int msg_count = 1;
 static struct TimingList *tl_head;
 
-static struct TimingList* write_first_node(void)
+static void init_new_list(void)
 {
 	tl_head = kmalloc(sizeof(struct TimingList), GFP_KERNEL);
-	tl_head->next = NULL;
 
-	return tl_head;
+	tl_head->next = NULL;
+	tl_head->t = ktime_get();
 }
 
-static struct TimingList* insert_next_node(struct TimingList *tail)
+static void insert_new_time(void)
 {
+	struct TimingList *last_tl_node = tl_head;
 	struct TimingList *new_tl_node = kmalloc(sizeof(struct TimingList),
 						GFP_KERNEL);
 
-	tail->next = new_tl_node;
+	while (last_tl_node->next != NULL)
+		last_tl_node = last_tl_node->next;
+
+
 	new_tl_node->next = NULL;
+	new_tl_node->t = ktime_get();
 
-	return new_tl_node;
+	last_tl_node->next = new_tl_node;
 }
 
-static struct TimingList* add_new_node(struct TimingList *tail)
+static void print_time(ktime_t *t)
 {
-	if (tail == NULL)
+	printk(KERN_EMERG "%lld\n", *t);
-		return write_first_node();
-	else
-		return insert_next_node(tail);
 }
 
-static void print_time_diff(struct TimingList *node)
+static void destroy_list(void)
-{
-	pr_info("%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_diff(curr_tl);
+		print_time(&(curr_tl->t));
 
 		next_tl = curr_tl->next;
 		kfree(curr_tl);
@@ -95,34 +89,38 @@ 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) {
-		pr_err("Error: msg_count too large (%d > 10)\n", msg_count);
+		printk(KERN_EMERG "Error: msg_count too large (%d > 10)\n",
+				msg_count);
 		return -EINVAL;
 	}
 
 	if (msg_count == 0 || msg_count >= 5) {
-		pr_warn("Warning: msg_count = %d (msg_count == 0 or 5 <= msg_count <= 10)\n", msg_count);
+		printk(KERN_EMERG "Warning: msg_count = %d (msg_count == 0 or 5 <= msg_count <= 10)\n",
+				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();
-		pr_info("Hello, world!\n");
-		current_tail->t_after = ktime_get();
-	}
-}
-
 static void __exit hello_exit(void)
 {
 	destroy_list();
@@ -131,8 +129,5 @@ 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

@@ -1,55 +0,0 @@
-
-/*
- * 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

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