list_for_each_safe和list_for_each_entry的区别

list_for_each_safe和list_for_each_entry是Linux内核中遍历链表的两种方法。它们的区别在于，list_for_each_safe可以删除当前遍历到的节点的下一个节点；而list_for_each_entry则可以根据链表节点中的成员偏移量，获取链表节点结构体的指针。这两种方法都比较常用，具体使用哪种方法取决于具体的需求。

相关问题

list_for_each_entry_safe和list_for_each_entry有什么区别

`list_for_each_entry`和`list_for_each_entry_safe`都是Linux内核中双向链表的遍历函数，区别在于它们的安全性。

`list_for_each_entry`是一个简单的遍历函数，它只遍历链表并执行回调函数，不会修改链表的结构。因此，它不需要额外的安全保护，适合在遍历期间不需要修改链表的情况下使用。

`list_for_each_entry_safe`在遍历链表时，可以安全地删除当前遍历节点，而不会影响下一个遍历节点的访问。它需要一个额外的临时节点来保护当前遍历节点，以防止删除当前节点后，下一个节点指针丢失。因此，`list_for_each_entry_safe`相对于`list_for_each_entry`来说更加安全，适合在遍历期间需要修改链表的情况下使用。

总之，`list_for_each_entry_safe`是`list_for_each_entry`的安全版本，它可以在修改链表的情况下遍历链表，并且不会影响其他遍历节点的访问。

list_for_each_entry_safe_reverse

list_for_each_entry_safe_reverse is a macro in the Linux kernel that is used to iterate over a doubly linked list in reverse order, while safely removing or modifying the entries in the list.

The macro takes four arguments:

1. pointer to the current entry in the list
2. pointer to the temporary variable used to store the next entry
3. pointer to the head of the list
4. name of the member in the struct that represents the list

Here is the syntax for the macro:

list_for_each_entry_safe_reverse(pos, n, head, member) {
    // do something with pos
}

The macro works by iterating over the list in reverse order, starting from the last entry and moving towards the head of the list. It uses a temporary variable (n) to store the next entry before modifying or removing the current entry (pos). This ensures that the list remains intact while the iteration is in progress.

Overall, list_for_each_entry_safe_reverse is a useful macro for safely iterating over and modifying doubly linked lists in the Linux kernel.