BSTRUCTMODULE: Add list

Add list of strings insted of int value. Add logs

Signed-off-by: Maryna Malakhova <[email protected]>

04_basic_struct/BBB_log.txt

@@ -0,0 +1,57 @@
+/mnt #
+/mnt # ls -la
+total 16
+drwxr-xr-x    2 root     root          4096 Mar 18  2021 .
+drwxr-xr-x   14 root     root          4096 Mar 18  2021 ..
+-rw-r--r--    1 root     root          5744 Mar 19  2021 bstructmodule.ko
+/mnt #
+/mnt #
+/mnt # dmesg -c
+/mnt #
+/mnt # lsmod
+/mnt #
+/mnt # insmod bstructmodule.ko
+/mnt #
+/mnt # lsmod
+bstructmodule 16384 0 - Live 0xbf018000 (O)
+/mnt #
+/mnt # dmesg
+/mnt #
+/mnt # cat /sys/kernel/hello/list
+/mnt #
+/mnt # echo first > /sys/kernel/hello/list
+[15507.266994] bstructmodule: store nodes: Added node = first
+/mnt #
+/mnt # echo second > /sys/kernel/hello/list
+[15518.703747] bstructmodule: store nodes: Added node = second
+/mnt #
+/mnt # cat /sys/kernel/hello/list
+second
+first
+/mnt #
+/mnt # echo third > /sys/kernel/hello/list
+[15563.359760] bstructmodule: store nodes: Added node = third
+/mnt #
+/mnt # cat /sys/kernel/hello/list
+third
+second
+first
+/mnt #
+/mnt # rmmod bstructmodule.ko
+[15586.216674] bstructmodule: remove node: third
+[15586.221264] bstructmodule: remove node: second
+[15586.226007] bstructmodule: remove node: first
+[15586.230584] bstructmodule: module exited
+/mnt #
+/mnt # dmesg
+[15507.266994] bstructmodule: store nodes: Added node = first
+[15518.703747] bstructmodule: store nodes: Added node = second
+[15563.359760] bstructmodule: store nodes: Added node = third
+[15586.216674] bstructmodule: remove node: third
+[15586.221264] bstructmodule: remove node: second
+[15586.226007] bstructmodule: remove node: first
+[15586.230584] bstructmodule: module exited
+/mnt #
+/mnt # lsmod
+/mnt #
+

04_basic_struct/bstructmodule.c

@@ -7,22 +7,43 @@
 #include <linux/err.h>
 #include <linux/string.h>
 #include <linux/sysfs.h>
+#include <linux/list.h>
+#include <linux/slab.h>
 
-static int value;
+struct list_node {
+	char *node;
+	struct list_head head_list;
+};
+
+LIST_HEAD(linkedlist);
 
 static ssize_t hello_show(struct kobject *kobj, struct kobj_attribute *attr,
 	char *buf)
 {
-	pr_info("hello_show: value = %d\n", value);
-	sprintf(buf, "%d\n", value);
-	return strlen(buf);
+	struct list_node *cur_node = NULL;
+	int offset = 0;
+	int res = 0;
+
+	list_for_each_entry(cur_node, &linkedlist, head_list) {
+		res = scnprintf(buf+offset, PAGE_SIZE-offset, "%s", cur_node->node);
+		offset += res;
+	}
+	return offset;
 }
 
 static ssize_t hello_store(struct kobject *kobj, struct kobj_attribute *attr,
 	const char *buf, size_t count)
 {
-	sscanf(buf, "%d\n", &value);
-	pr_info("hello_store: value = %d\n", value);
+	struct list_node *new_node =
+		kmalloc(sizeof(struct list_node), GFP_KERNEL);
+
+	if (!new_node)
+		return -ENOMEM;
+	new_node->node = kstrdup(buf, GFP_KERNEL);
+	if (new_node->node == NULL)
+		return -ENOMEM;
+	list_add_tail(&new_node->head_list, &linkedlist);
+	pr_info("store nodes: Added node = %s", buf);
 	return count;
 }
 
@@ -57,6 +78,15 @@ static int __init hello_init(void)
 
 static void __exit hello_exit(void)
 {
+	struct list_node *cur_node = NULL;
+	struct list_node *tmp_node = NULL;
+
+	list_for_each_entry_safe(cur_node, tmp_node, &linkedlist, head_list) {
+		pr_info("remove node: %s", cur_node->node);
+		list_del(&cur_node->head_list);
+		kfree(cur_node->node);
+		kfree(cur_node);
+	}
 	kobject_put(hello_kobj);
 	pr_info("module exited\n");
 }

04_basic_struct/checkpatch_log.txt

@@ -0,0 +1,4 @@
+total: 0 errors, 0 warnings, 100 lines checked
+
+/home/marynam/Maryna/KernelProCamp21/gl-kernel-training-2021/04_basic_struct/bstructmodule.c has no obvious style problems and is ready for submission.
+