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+/*
+ * Burrowed from the Linux kernel.
+ */
+
+#ifndef _RATPOISON_LINKLIST_H
+#define _RATPOISON_LINKLIST_H
+
+static inline void prefetch(const void *x) {;}
+
+/*
+ * Simple doubly linked list implementation.
+ *
+ * Some of the internal functions ("__xxx") are useful when
+ * manipulating whole lists rather than single entries, as
+ * sometimes we already know the next/prev entries and we can
+ * generate better code by using them directly rather than
+ * using the generic single-entry routines.
+ */
+
+struct list_head {
+ struct list_head *next, *prev;
+};
+
+#define LIST_HEAD_INIT(name) { &(name), &(name) }
+
+#define LIST_HEAD(name) \
+ struct list_head name = LIST_HEAD_INIT(name)
+
+#define INIT_LIST_HEAD(ptr) do { \
+ (ptr)->next = (ptr); (ptr)->prev = (ptr); \
+} while (0)
+
+/*
+ * Insert a new entry between two known consecutive entries.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ */
+static inline void __list_add(struct list_head *new,
+ struct list_head *prev,
+ struct list_head *next)
+{
+ next->prev = new;
+ new->next = next;
+ new->prev = prev;
+ prev->next = new;
+}
+
+/**
+ * list_add - add a new entry
+ * @new: new entry to be added
+ * @head: list head to add it after
+ *
+ * Insert a new entry after the specified head.
+ * This is good for implementing stacks.
+ */
+static inline void list_add(struct list_head *new, struct list_head *head)
+{
+ __list_add(new, head, head->next);
+}
+
+/**
+ * list_add_tail - add a new entry
+ * @new: new entry to be added
+ * @head: list head to add it before
+ *
+ * Insert a new entry before the specified head.
+ * This is useful for implementing queues.
+ */
+static inline void list_add_tail(struct list_head *new, struct list_head *head)
+{
+ __list_add(new, head->prev, head);
+}
+
+/*
+ * Delete a list entry by making the prev/next entries
+ * point to each other.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ */
+static inline void __list_del(struct list_head * prev, struct list_head * next)
+{
+ next->prev = prev;
+ prev->next = next;
+}
+
+/**
+ * list_del - deletes entry from list.
+ * @entry: the element to delete from the list.
+ * Note: list_empty on entry does not return true after this, the entry is
+ * in an undefined state.
+ */
+static inline void list_del(struct list_head *entry)
+{
+ __list_del(entry->prev, entry->next);
+}
+
+/**
+ * list_del_init - deletes entry from list and reinitialize it.
+ * @entry: the element to delete from the list.
+ */
+static inline void list_del_init(struct list_head *entry)
+{
+ __list_del(entry->prev, entry->next);
+ INIT_LIST_HEAD(entry);
+}
+
+/**
+ * list_move - delete from one list and add as another's head
+ * @list: the entry to move
+ * @head: the head that will precede our entry
+ */
+static inline void list_move(struct list_head *list, struct list_head *head)
+{
+ __list_del(list->prev, list->next);
+ list_add(list, head);
+}
+
+/**
+ * list_move_tail - delete from one list and add as another's tail
+ * @list: the entry to move
+ * @head: the head that will follow our entry
+ */
+static inline void list_move_tail(struct list_head *list,
+ struct list_head *head)
+{
+ __list_del(list->prev, list->next);
+ list_add_tail(list, head);
+}
+
+/**
+ * list_empty - tests whether a list is empty
+ * @head: the list to test.
+ */
+static inline int list_empty(struct list_head *head)
+{
+ return head->next == head;
+}
+
+static inline void __list_splice(struct list_head *list,
+ struct list_head *head)
+{
+ struct list_head *first = list->next;
+ struct list_head *last = list->prev;
+ struct list_head *at = head->next;
+
+ first->prev = head;
+ head->next = first;
+
+ last->next = at;
+ at->prev = last;
+}
+
+/**
+ * list_splice - join two lists
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ */
+static inline void list_splice(struct list_head *list, struct list_head *head)
+{
+ if (!list_empty(list))
+ __list_splice(list, head);
+}
+
+/**
+ * list_splice_init - join two lists and reinitialise the emptied list.
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ *
+ * The list at @list is reinitialised
+ */
+static inline void list_splice_init(struct list_head *list,
+ struct list_head *head)
+{
+ if (!list_empty(list)) {
+ __list_splice(list, head);
+ INIT_LIST_HEAD(list);
+ }
+}
+
+/**
+ * container_of - cast a member of a structure out to the containing structure
+ *
+ * @ptr: the pointer to the member.
+ * @type: the type of the container struct this is embedded in.
+ * @member: the name of the member within the struct.
+ *
+ */
+#define container_of(ptr, type, member) ({ \
+ const typeof( ((type *)0)->member ) *__mptr = (ptr); \
+ (type *)( (char *)__mptr - offsetof(type,member) );})
+
+/**
+ * list_entry - get the struct for this entry
+ * @ptr: the &struct list_head pointer.
+ * @type: the type of the struct this is embedded in.
+ * @member: the name of the list_struct within the struct.
+ */
+#define list_entry(ptr, type, member) \
+ container_of(ptr, type, member)
+
+
+/**
+ * __list_for_each - iterate over a list
+ * @pos: the &struct list_head to use as a loop counter.
+ * @head: the head for your list.
+ *
+ * This variant differs from list_for_each() in that it's the
+ * simplest possible list iteration code, no prefetching is done.
+ * Use this for code that knows the list to be very short (empty
+ * or 1 entry) most of the time.
+ */
+#define list_for_each(pos, head) \
+ for (pos = (head)->next; pos != (head); pos = pos->next)
+
+/**
+ * list_for_each_prev - iterate over a list backwards
+ * @pos: the &struct list_head to use as a loop counter.
+ * @head: the head for your list.
+ */
+#define list_for_each_prev(pos, head) \
+ for (pos = (head)->prev, prefetch(pos->prev); pos != (head); \
+ pos = pos->prev, prefetch(pos->prev))
+
+/**
+ * list_for_each_safe - iterate over a list safe against removal of list entry
+ * @pos: the &struct list_head to use as a loop counter.
+ * @n: another &struct list_head to use as temporary storage
+ * @head: the head for your list.
+ */
+#define list_for_each_safe(pos, n, head) \
+ for (pos = (head)->next, n = pos->next; pos != (head); \
+ pos = n, n = pos->next)
+
+#define list_for_each_safe_entry(item, pos, n, head, member) \
+ for (pos = (head)->next, \
+ item = list_entry(pos, typeof(*item), member), \
+ n = pos->next \
+ ; \
+ pos != (head) \
+ ; \
+ pos = n, \
+ item = list_entry(pos, typeof(*item), member), \
+ n = pos->next) \
+
+/**
+ * list_for_each_entry - iterate over list of given type
+ * @pos: the type * to use as a loop counter.
+ * @head: the head for your list.
+ * @member: the name of the list_struct within the struct.
+ */
+#define list_for_each_entry(pos, head, member) \
+ for (pos = list_entry((head)->next, typeof(*pos), member), \
+ prefetch(pos->member.next); \
+ &pos->member != (head); \
+ pos = list_entry(pos->member.next, typeof(*pos), member), \
+ prefetch(pos->member.next))
+
+#define list_for_each_entry_safe(pos, n, head, member) \
+ for (pos = list_entry((head)->next, typeof(*pos), member), \
+ n = list_entry(pos->member.next, typeof(*pos), member); \
+ &pos->member != (head); \
+ pos = n, \
+ n = list_entry(pos->member.next, typeof(*pos), member))
+
+#define list_direction_entry(pos, head, member, direction) \
+({ \
+ typeof(pos) ret = NULL; \
+ struct list_head *a_head = head; \
+ if (pos->member.direction == a_head) { \
+ if (a_head->direction != &pos->member) \
+ ret = list_entry(a_head->direction, \
+ typeof(*pos), member); \
+ } else { \
+ ret = list_entry(pos->member.direction, \
+ typeof(*pos), member); \
+ } \
+ ret; \
+})
+
+#define list_next_entry(pos, head, member) \
+ list_direction_entry(pos, head, member, next)
+
+#define list_prev_entry(pos, head, member) \
+ list_direction_entry(pos, head, member, prev)
+
+#define list_for_each_entry_prev(pos, head, member) \
+ for (pos = list_entry((head)->prev, typeof(*pos), member), \
+ prefetch(pos->member.prev); \
+ &pos->member != (head); \
+ pos = list_entry(pos->member.prev, typeof(*pos), member), \
+ prefetch(pos->member.prev))
+
+#endif