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authorRicardo Martinez <ricardo.martinez@linux.intel.com>2022-05-06 11:12:57 -0700
committerDavid S. Miller <davem@davemloft.net>2022-05-09 10:51:58 +0100
commit2fbdf45d7d26361a0c3ec8833fd96edf0f5812da (patch)
tree656bac038c34f0ba955ddb466d39d32cc0a9acde /include/linux/list.h
parentc908565eecf2d310edddaecea6166015abe9df08 (diff)
list: Add list_next_entry_circular() and list_prev_entry_circular()
Add macros to get the next or previous entries and wraparound if needed. For example, calling list_next_entry_circular() on the last element should return the first element in the list. Signed-off-by: Ricardo Martinez <ricardo.martinez@linux.intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/list.h')
-rw-r--r--include/linux/list.h26
1 files changed, 26 insertions, 0 deletions
diff --git a/include/linux/list.h b/include/linux/list.h
index dd6c2041d09c..c147eeb2d39d 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -564,6 +564,19 @@ static inline void list_splice_tail_init(struct list_head *list,
list_entry((pos)->member.next, typeof(*(pos)), member)
/**
+ * list_next_entry_circular - get the next element in list
+ * @pos: the type * to cursor.
+ * @head: the list head to take the element from.
+ * @member: the name of the list_head within the struct.
+ *
+ * Wraparound if pos is the last element (return the first element).
+ * Note, that list is expected to be not empty.
+ */
+#define list_next_entry_circular(pos, head, member) \
+ (list_is_last(&(pos)->member, head) ? \
+ list_first_entry(head, typeof(*(pos)), member) : list_next_entry(pos, member))
+
+/**
* list_prev_entry - get the prev element in list
* @pos: the type * to cursor
* @member: the name of the list_head within the struct.
@@ -572,6 +585,19 @@ static inline void list_splice_tail_init(struct list_head *list,
list_entry((pos)->member.prev, typeof(*(pos)), member)
/**
+ * list_prev_entry_circular - get the prev element in list
+ * @pos: the type * to cursor.
+ * @head: the list head to take the element from.
+ * @member: the name of the list_head within the struct.
+ *
+ * Wraparound if pos is the first element (return the last element).
+ * Note, that list is expected to be not empty.
+ */
+#define list_prev_entry_circular(pos, head, member) \
+ (list_is_first(&(pos)->member, head) ? \
+ list_last_entry(head, typeof(*(pos)), member) : list_prev_entry(pos, member))
+
+/**
* list_for_each - iterate over a list
* @pos: the &struct list_head to use as a loop cursor.
* @head: the head for your list.