Update

Author: smalinux

Makefile

@@ -7,6 +7,7 @@ obj-m += net.o
 #obj-m += netfilter.o
 obj-m += list.o				# <linux/list.h>
 obj-m += hashtable.o			# <linux/hashtable.h>
+obj-m += phone_table.o			# simple hashtable.h example
 obj-m += container_of.o			# Now I understand container_macro deeply ..
 obj-m += container_of_container_of.o
 #obj-m += cdev.o 			# complete char device

README.adoc

@@ -11,4 +11,7 @@ image:images/list.png[alt text]
 #### link:../main/hashtable.c[hashtable.c] dmesg
 image:images/hashtable.png[alt text]
 
+#### link:../main/phone_table.c[phone_table.c] dmesg
+image:images/phone_table.png[alt text]
+
 

hashtable.c

@@ -1,6 +1,3 @@
-/**
- * Reference	https://stackoverflow.com/a/60873789/5688267
- */
 #include <linux/hashtable.h> // hashtable API
 #include <linux/module.h>    // module_{init,exit}, MODULE_*
 #include <linux/string.h>    // strcpy, strcmp
@@ -106,3 +103,7 @@ module_exit(myhashtable_exit);
 MODULE_VERSION("0.1");
 MODULE_DESCRIPTION("Silly kernel hashtable API example module.");
 MODULE_AUTHOR("Sohaib Mhmd");
+/**
+ * Link:
+ * https://stackoverflow.com/a/60873789/5688267
+ */

hello.c

@@ -1,6 +1,3 @@
-/*                                                     
- * LDD3 P: 16
- */                                                    
 #include <linux/init.h>
 #include <linux/module.h>
 MODULE_LICENSE("GPL");

images/phone_table.png

@@ -0,0 +1,110 @@
+#include <linux/hashtable.h>
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/slab.h>		// kmalloc()
+MODULE_LICENSE("GPL");
+
+#define LENGTH 11
+
+typedef struct num_node {
+	char data[LENGTH];
+	struct hlist_node node;
+} num_node;
+
+DECLARE_HASHTABLE(tbl, 3);
+
+// Just to demonstrate the behavior when two keys are equal.
+static u32 myhash(const char *s)
+{
+	u32 key = 0;
+	char c;
+
+	//pr_err("Calculating the key of %s....", s);
+
+	while ((c = *s++)) {
+		key += c;
+		//pr_err("key = %u\n", key);
+	}
+
+	return key;
+}
+
+static u32 add_num(char * num)
+{
+	u32 key;
+	struct num_node *a = kmalloc(sizeof(num_node), GFP_KERNEL);
+	strcpy(a->data, num);
+	key = myhash(a->data);
+	hash_add(tbl, &a->node, key);
+	pr_err("Phone num %s added!\n", a->data);
+	return key;
+};
+
+static int __init myhashtable_init(void)
+{
+	struct num_node *cur;
+	unsigned bkt;
+	u32 key;
+
+	pr_info("myhashtable: module loaded\n");
+
+	// Initialize the hashtable.
+	hash_init(tbl);
+
+	key = add_num("01157133430");
+	add_num("01157133403");
+	add_num("01157134303");
+	add_num("01157122403");
+	add_num("01157166403");
+
+
+	add_num("01111111111");
+	add_num("01122222222");
+	add_num("01133333333");
+	add_num("01144444444");
+	add_num("01155555555");
+
+	// List all elements in the table.
+	pr_cont("List all elements in the table");
+	hash_for_each(tbl, bkt, cur, node) {
+        	pr_info("myhashtable: Phone num = %s\n", 
+				cur->data);
+	}
+
+	// Get the element = "01157133430".
+	pr_cont("Get the phone number = \"01157133430\"");
+	hash_for_each_possible(tbl, cur, node, key) {
+		pr_info("myhashtable: match for key %u: Phone = %s\n",
+				key, cur->data);
+
+		// Check the value
+		if (!strcmp(cur->data, "01157133430")) {
+			pr_err("myhashtable: \"01157133430\" found!\n");
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static void myhashtable_exit(void)
+{
+
+	struct num_node *cur;
+	unsigned bkt;
+
+	// Remove elements.
+	hash_for_each(tbl, bkt, cur, node) {
+		hash_del_rcu(&cur->node);
+	}
+
+	hash_for_each(tbl, bkt, cur, node) {
+        	pr_info("myhashtable: Phone num = %s\n", 
+				cur->data);
+	}
+
+	pr_info("myhashtable: module unloaded\n");
+}
+
+module_init(myhashtable_init);
+module_exit(myhashtable_exit);