#include <stddef.h> /* offsetof */
+/** 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) );})
-/*
- * These are non-NULL pointers that will result in page faults
- * under normal circumstances, used to verify that nobody uses
- * non-initialized list entries.
+/**
+ * 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.
- *
+/** Simple doubly linked list implementation. */
+struct list_head {
+ /** pointer to the next list entry */
+ struct list_head *next;
+ /** 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)
+
+
+/*
* 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 INIT_LIST_HEAD(ptr) do { \
- (ptr)->next = (ptr); (ptr)->prev = (ptr); \
-} while (0)
/*
* Insert a new entry between two known consecutive entries.
#define list_entry(ptr, type, member) \
container_of(ptr, type, member)
-/**
- * iterate over a list safe against removal of list entry
- *
- * \param pos the &struct list_head to use as a loop counter.
- * \param n another &struct list_head to use as temporary storage
- * \param 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)
-
/**
* iterate over list of given type
*
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.
+ * \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.
+ */
+#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);
+}
+