initial commit

Makefile

@@ -0,0 +1,13 @@
+
+ifneq ($(KERNELRELEASE),)
+# kbuild part of makefile
+obj-m   := hello.o
+else
+# normal makefile
+KDIR ?= /lib/modules/`uname -r`/build
+
+default:
+	$(MAKE) -C $(KDIR) M=$$PWD
+clean:
+	$(MAKE) -C $(KDIR) M=$$PWD clean
+endif

hello.c

@@ -0,0 +1,134 @@
+
+/*
+ * 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>
+
+MODULE_AUTHOR("Serhii Popovych <serhii.popovych@globallogic.com>");
+MODULE_DESCRIPTION("Hello, world in Linux Kernel Training");
+MODULE_LICENSE("Dual BSD/GPL");
+
+struct TimingList {
+	struct TimingList *next;
+	ktime_t t;
+};
+
+static unsigned int msg_count = 1;
+static struct TimingList *tl_head = NULL;
+
+static void init_new_list(void)
+{
+	tl_head = kmalloc(sizeof(struct TimingList), GFP_KERNEL);
+
+	tl_head->next = NULL;
+	tl_head->t = ktime_get();
+}
+
+static void insert_new_time(void)
+{
+	struct TimingList *last_tl_node = tl_head;
+	struct TimingList *new_tl_node = kmalloc(sizeof(struct TimingList),
+						GFP_KERNEL);
+
+	while (last_tl_node->next != NULL)
+		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;
+}
+
+static void print_time(ktime_t *t)
+{
+	printk(KERN_EMERG "%lld\n", *t);
+}
+
+static void destroy_list(void)
+{
+	struct TimingList *curr_tl = tl_head;
+	struct TimingList *next_tl = NULL;
+
+	while (curr_tl != NULL) {
+		print_time(&(curr_tl->t));
+
+		next_tl = curr_tl->next;
+		kfree(curr_tl);
+		curr_tl = next_tl;
+	}
+}
+
+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);
+		return -EINVAL;
+	}
+
+	if (msg_count == 0 || msg_count >= 5) {
+		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;
+}
+
+static void __exit hello_exit(void)
+{
+	destroy_list();
+}
+
+module_param(msg_count, uint, 0444);
+MODULE_PARM_DESC(msg_count, "Amount of hello world outputs on load");
+
+module_init(hello_init);
+module_exit(hello_exit);