* Copied from the Linux kernel source tree, version 2.6.13.
*
* Licensed under the GPL v2 as per the whole kernel source tree.
- *
*/
-/** \file list.h doubly linked list implementation */
+/** \file list.h Doubly linked list implementation. */
#include <stddef.h> /* offsetof */
-/** get the struct this entry is embedded in */
+/** Get the struct this entry is embedded in. */
#define container_of(ptr, type, member) ({ \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) );})
-/**
- * Non-NULL pointers that will result in page faults under normal
- * circumstances, used to verify that nobody uses non-initialized list entries.
- * Used for poisoning the \a next pointer of struct list_head.
- */
-#define LIST_POISON1 ((void *) 0x00100100)
-/** Non-null pointer, used for poisoning the \a prev pointer of struct
- * list_head
- */
-#define LIST_POISON2 ((void *) 0x00200200)
-
-/** Simple doubly linked list implementation. */
+/** A list head is just a pair of pointers. */
struct list_head {
- /** pointer to the next list entry */
+ /** Pointer to the next list entry. */
struct list_head *next;
- /** pointer to the previous list entry */
+ /** Pointer to the previous list entry. */
struct list_head *prev;
};
/** Define an initialized list head. */
-#define INITIALIZED_LIST_HEAD(name) struct list_head name = { &(name), &(name) }
-
-
-/** must be called before using any other list functions */
-#define INIT_LIST_HEAD(ptr) do { \
- (ptr)->next = (ptr); (ptr)->prev = (ptr); \
-} while (0)
+#define INITIALIZED_LIST_HEAD(name) struct list_head name = {&(name), &(name)}
-
-/*
- * 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.
- */
-
-
-/*
- * 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)
+/** This must be called before using any other list functions. */
+static inline void init_list_head(struct list_head *head)
{
- next->prev = new;
- new->next = next;
- new->prev = prev;
- prev->next = new;
+ head->next = head;
+ head->prev = head;
}
/**
- * add a new entry
+ * Insert a new entry after the specified head.
*
- * \param new new entry to be added
- * \param head list head to add it after
+ * \param entry The new entry to add.
+ * \param head The list head to add it after.
*
- * Insert a new entry after the specified head.
* This is good for implementing stacks.
*/
-static inline void para_list_add(struct list_head *new, struct list_head *head)
+static inline void para_list_add(struct list_head *entry, struct list_head *head)
{
- __list_add(new, head, head->next);
+ entry->prev = head;
+ entry->next = head->next;
+ head->next->prev = entry;
+ head->next = entry;
}
/**
- * add a new entry
+ * Insert a new entry before the specified head.
*
- * \param new new entry to be added
- * \param head list head to add it before
+ * \param entry The new entry to add.
+ * \param 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)
+static inline void list_add_tail(struct list_head *entry, struct list_head *head)
{
- __list_add(new, head->prev, head);
+ entry->prev = head->prev;
+ entry->next = head;
+ head->prev->next = entry;
+ head->prev = entry;
}
-/*
- * Delete a list entry by making the prev/next entries
- * point to each other.
+/**
+ * Delete an entry from a list.
+ *
+ * \param entry The element to delete.
*
- * This is only for internal list manipulation where we know
- * the prev/next entries already!
+ * The list entry is in an undefined state after this and \ref list_empty()
+ * does not return true.
*/
-static inline void __list_del(struct list_head * prev, struct list_head * next)
+static inline void list_del(struct list_head *entry)
{
- next->prev = prev;
- prev->next = next;
+ entry->prev->next = entry->next;
+ entry->next->prev = entry->prev;
+ /*
+ * These non-NULL pointers result in page faults when dereferenced.
+ * This helps to catch bugs resulting from using deleted list heads.
+ */
+ entry->next = (void *)0x00100100;
+ entry->prev = (void *)0x00200200;
}
/**
- * Delete entry from list.
- *
- * \param entry the element to delete from the list.
+ * Delete an entry from one list and add it as another list's head.
*
- * Note: list_empty on entry does not return true after this, the entry is
- * in an undefined state.
+ * \param entry The entry to move.
+ * \param head The head that will precede our entry.
*/
-static inline void list_del(struct list_head *entry)
+static inline void list_move(struct list_head *entry, struct list_head *head)
{
- __list_del(entry->prev, entry->next);
- entry->next = LIST_POISON1;
- entry->prev = LIST_POISON2;
+ list_del(entry);
+ para_list_add(entry, head);
}
/**
- * delete from one list and add as another's head
+ * Test whether a list contains no entries.
*
- * \param list: the entry to move
- * \param head: the head that will precede our entry
+ * \param head The list to test.
*/
-static inline void list_move(struct list_head *list, struct list_head *head)
+static inline int list_empty(const struct list_head *head)
{
- __list_del(list->prev, list->next);
- para_list_add(list, head);
+ return head->next == head;
}
/**
- * test whether a list is empty
+ * Test whether a list has just one entry.
*
- * \param head the list to test.
+ * \param head The list to test.
*/
-static inline int list_empty(const struct list_head *head)
+static inline int list_is_singular(const struct list_head *head)
{
- return head->next == head;
+ return !list_empty(head) && (head->next == head->prev);
}
/**
- * get the struct for this entry
+ * Get the struct in which this entry is embedded in.
*
- * \param ptr the &struct list_head pointer.
- * \param type the type of the struct this is embedded in.
- * \param member the name of the list_struct within the struct.
+ * \param ptr The list head pointer.
+ * \param type The type of containing structure.
+ * \param member The name of the list head member within the structure.
*/
-#define list_entry(ptr, type, member) \
- container_of(ptr, type, member)
+#define list_entry(ptr, type, member) container_of(ptr, type, member)
/**
- * iterate over list of given type
+ * Iterate over a list.
*
- * \param pos the type * to use as a loop counter.
- * \param head the head for your list.
- * \param member the name of the list_struct within the struct.
+ * \param pos A struct pointer which serves as the iterator.
+ * \param head The head of the list.
+ * \param member The name of the list head member within the structure.
*/
#define list_for_each_entry(pos, head, member) \
for (pos = list_entry((head)->next, typeof(*pos), member); \
pos = list_entry(pos->member.next, typeof(*pos), member))
/**
- * iterate over list of given type safe against removal of list entry
+ * Iterate over list, safe against removal of list entry.
*
- * \param pos the type * to use as a loop counter.
- * \param n another type * to use as temporary storage
- * \param head the head for your list.
- * \param member the name of the list_struct within the struct.
+ * \param pos The iterator struct pointer.
+ * \param n A second struct pointer which is used as temporary storage.
+ * \param head The head of the list.
+ * \param member The name of the list head member within the structure.
*/
#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(n->member.next, typeof(*n), member))
-/**
- * iterate backwards over list of given type safe against removal of list entry
- * \param pos the type * to use as a loop counter.
- * \param n another type * to use as temporary storage
- * \param head the head for your list.
- * \param member the name of the list_struct within the struct.
- */
-#define list_for_each_entry_safe_reverse(pos, n, head, member) \
- for (pos = list_entry((head)->prev, typeof(*pos), member), \
- n = list_entry(pos->member.prev, typeof(*pos), member); \
- &pos->member != (head); \
- pos = n, n = list_entry(n->member.prev, typeof(*n), member))
/**
- * Get the first element from a list
- * \param ptr the list head to take the element from.
+ * Get the first element of a list.
+ *
+ * \param ptr The list head to take the element from.
* \param type The type of the struct this is embedded in.
* \param member The name of the list_struct within the struct.
*
- * Note that list is expected to be not empty.
+ * Note that the list is expected to be non-empty.
*/
#define list_first_entry(ptr, type, member) \
- list_entry((ptr)->next, type, member)
-
-/**
- * Test whether a list has just one entry.
- *
- * \param head The list to test.
- */
-static inline int list_is_singular(const struct list_head *head)
-{
- return !list_empty(head) && (head->next == head->prev);
-}
-
+ list_entry((ptr)->next, type, member)
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