list_for_each_entry

list_for_each_entry is a macro in the Linux kernel that is used to iterate over a linked list of a particular type of data structures.

Syntax:

list_for_each_entry(pos, head, member)

Parameters:
- pos: A pointer to the current element of the list being processed.
- head: A pointer to the head of the list being processed.
- member: The name of the list_head field within the data structure type.

Usage:
- This macro is commonly used in kernel code that maintains linked lists of data structures.
- It is used to iterate over the list and perform some operation on each element of the list.
- The macro takes care of the pointer arithmetic involved in traversing the list and accessing the data structures.

Example:

struct my_struct {
    int data;
    struct list_head list;
};

struct list_head my_list;

struct my_struct *ptr;

// Add some elements to the list

list_for_each_entry(ptr, &my_list, list) {
    printk(KERN_INFO "Data: %d\n", ptr->data);
}

In the above example, list_for_each_entry is used to iterate over a list of my_struct data structures. The macro is used to print the data field of each element in the list.