0002-Use-kernel-api-in-hello-module.patch

From 40232a43d57aed77bd6be45d583c7af26a721312 Mon Sep 17 00:00:00 2001
From: "Hossein.Assaran" <Hossein.Assaran@gmail.com>
Date: Fri, 10 Jul 2020 11:02:29 +0430
Subject: [PATCH] Use kernel api in hello module

---
 drivers/test-module/hello.c | 67 ++++++++++++++++++++++++++++++++-----
 1 file changed, 58 insertions(+), 9 deletions(-)

diff --git a/drivers/test-module/hello.c b/drivers/test-module/hello.c
index d18d3fc52..64918bf03 100644
--- a/drivers/test-module/hello.c
+++ b/drivers/test-module/hello.c
@@ -2,34 +2,83 @@
 #include <linux/moduleparam.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/string.h>
 
 static char *string = "Hello world";
 module_param(string,charp,S_IRUSR | S_IWUSR);
 MODULE_PARM_DESC(string, "The string to be printed");
 
+static int count = 5;
+module_param(count, int, S_IRUSR | S_IWUSR);
+MODULE_PARM_DESC(count, "The number of objects");
+
+static char **string_list = 0;
+
 int add(int a, int b)
 {
 	return a+b;
 }
 EXPORT_SYMBOL(add);
 
+typedef struct my_dev {
+	 char *name;
+	 int id;
+}my_dev;
+
+static int count_backup;
 static int __init hello_init(void)
 {
-#ifdef CONFIG_HELLO_COUNT
-	int count = CONFIG_HELLO_COUNT;
-#else
-	int count = 5;
-#endif
+	int i = 0;
+	int ret_code = 0;
 	if (count <0)
 		count = 0;
-	while(count--)
-		pr_alert("%s\n",string);
-	pr_alert("2+5 is %d\n", add(2,5));
-	return 0;
+	if (count > 9999)
+		count = 9999;
+	string_list = kcalloc(count, sizeof(char*), GFP_KERNEL);
+	if (!string_list){
+		 pr_alert("No memo!\n");
+		 ret_code = -ENOMEM;
+		 goto exit_point1;
+	}
+	char *name = kmalloc(sizeof("device_0000"), GFP_KERNEL);
+	count_backup = count;
+	if(!name){
+		pr_alert("No memory!\n");
+		ret_code = -ENOMEM;
+		goto exit_point;
+	}
+	for (i = 0; i < count ; i++) {
+		sprintf(name, "device_%04d", i);
+		string_list[i] = kstrdup(name, GFP_KERNEL);
+        pr_alert("Adding new device: %s\n", string_list[i]);
+		if (!string_list[i]){
+			 pr_alert("No Memory for %d-th object\n", i);
+			ret_code = -ENOMEM;
+			goto exit_point;
+		}
+	}
+
+exit_point:
+	kfree (name);
+	if(ret_code && i){
+		do{
+			kfree(string_list[--i]);
+		}while(i);
+		kfree(string_list);
+	}
+exit_point1:
+	return ret_code;
 }
 
 static void __exit hello_exit(void)
 {
+	int i;
+	for (i = 0; i < count_backup; i++){
+		pr_alert("device name %d = %s\n", i, string_list[i]);
+		kfree(string_list[i]);
+	}
+	kfree(string_list);
 	pr_alert("Good bye the string was %s\n", string);
 }
 
-- 
2.17.1