Handy to get last item in a list. Also corrected parameter name for
list_first_entry.
Signed-off-by: Jiri Pirko <[email protected]>
diff --git a/include/linux/list.h b/include/linux/list.h
index 3a54266..e10862e 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -352,14 +352,25 @@ static inline void list_splice_tail_init(struct list_head *list,
/**
* list_first_entry - get the first element from a list
- * @ptr: the list head to take the element from.
+ * @head: the list head to take the element from.
* @type: the type of the struct this is embedded in.
* @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)
+#define list_first_entry(head, type, member) \
+ list_entry((head)->next, type, member)
+
+/**
+ * list_last_entry - get the last element from a list
+ * @head: the list head to take the element from.
+ * @type: the type of the struct this is embedded in.
+ * @member: the name of the list_struct within the struct.
+ *
+ * Note, that list is expected to be not empty.
+ */
+#define list_last_entry(head, type, member) \
+ list_entry((head)->prev, type, member)
/**
* list_for_each - iterate over a list
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 2dea94f..2cfa99f 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -229,7 +229,7 @@ static inline void list_splice_init_rcu(struct list_head *list,
/**
* list_first_entry_rcu - get the first element from a list
- * @ptr: the list head to take the element from.
+ * @head: the list head to take the element from.
* @type: the type of the struct this is embedded in.
* @member: the name of the list_struct within the struct.
*
@@ -238,8 +238,23 @@ static inline void list_splice_init_rcu(struct list_head *list,
* This primitive may safely run concurrently with the _rcu list-mutation
* primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
*/
-#define list_first_entry_rcu(ptr, type, member) \
- list_entry_rcu((ptr)->next, type, member)
+#define list_first_entry_rcu(head, type, member) \
+ list_entry_rcu((head)->next, type, member)
+
+/**
+ * list_last_entry_rcu - get the last element from a list
+ * @head: the list head to take the element from.
+ * @type: the type of the struct this is embedded in.
+ * @member: the name of the list_struct within the struct.
+ *
+ * Note, that list is expected to be not empty.
+ *
+ * This primitive may safely run concurrently with the _rcu list-mutation
+ * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
+ */
+
+#define list_last_entry_rcu(head, type, member) \
+ list_entry_rcu((head)->prev, type, member)
/**
* list_for_each_entry_rcu - iterate over rcu list of given type
On Sun, Feb 27, 2011 at 11:46:21AM +0100, Jiri Pirko wrote:
> Handy to get last item in a list. Also corrected parameter name for
> list_first_entry.
>
> Signed-off-by: Jiri Pirko <[email protected]>
>
> diff --git a/include/linux/list.h b/include/linux/list.h
> index 3a54266..e10862e 100644
> --- a/include/linux/list.h
> +++ b/include/linux/list.h
> @@ -352,14 +352,25 @@ static inline void list_splice_tail_init(struct list_head *list,
>
> /**
> * list_first_entry - get the first element from a list
> - * @ptr: the list head to take the element from.
> + * @head: the list head to take the element from.
> * @type: the type of the struct this is embedded in.
> * @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)
> +#define list_first_entry(head, type, member) \
> + list_entry((head)->next, type, member)
> +
> +/**
> + * list_last_entry - get the last element from a list
> + * @head: the list head to take the element from.
> + * @type: the type of the struct this is embedded in.
> + * @member: the name of the list_struct within the struct.
> + *
> + * Note, that list is expected to be not empty.
> + */
> +#define list_last_entry(head, type, member) \
> + list_entry((head)->prev, type, member)
>
> /**
> * list_for_each - iterate over a list
> diff --git a/include/linux/rculist.h b/include/linux/rculist.h
> index 2dea94f..2cfa99f 100644
> --- a/include/linux/rculist.h
> +++ b/include/linux/rculist.h
> @@ -229,7 +229,7 @@ static inline void list_splice_init_rcu(struct list_head *list,
>
> /**
> * list_first_entry_rcu - get the first element from a list
> - * @ptr: the list head to take the element from.
> + * @head: the list head to take the element from.
> * @type: the type of the struct this is embedded in.
> * @member: the name of the list_struct within the struct.
> *
> @@ -238,8 +238,23 @@ static inline void list_splice_init_rcu(struct list_head *list,
> * This primitive may safely run concurrently with the _rcu list-mutation
> * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
> */
> -#define list_first_entry_rcu(ptr, type, member) \
> - list_entry_rcu((ptr)->next, type, member)
> +#define list_first_entry_rcu(head, type, member) \
> + list_entry_rcu((head)->next, type, member)
> +
> +/**
> + * list_last_entry_rcu - get the last element from a list
> + * @head: the list head to take the element from.
> + * @type: the type of the struct this is embedded in.
> + * @member: the name of the list_struct within the struct.
> + *
> + * Note, that list is expected to be not empty.
> + *
> + * This primitive may safely run concurrently with the _rcu list-mutation
> + * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
> + */
> +
> +#define list_last_entry_rcu(head, type, member) \
> + list_entry_rcu((head)->prev, type, member)
But won't a concurrent list_del_rcu() on head, which removes the full
list, poison the ->prev pointer?
Do you have a definite use case for list_last_entry_rcu()?
Thanx, Paul
> /**
> * list_for_each_entry_rcu - iterate over rcu list of given type
> --
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