list_size counts the number of entries. list_at_index retrieves the
entry at an index. list_for_each_from iterates over a list from some
entry to the end.
Signed-off-by: Ole Schuerks <ole0811sch@gmail.com>
---
scripts/include/list.h | 49 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 49 insertions(+)
diff --git a/scripts/include/list.h b/scripts/include/list.h
index 8bdcaadca709..0c50774606c2 100644
--- a/scripts/include/list.h
+++ b/scripts/include/list.h
@@ -219,6 +219,21 @@ static inline int list_empty(const struct list_head *head)
return head->next == head;
}
+/**
+ * list_size - counts the number of entries in a list
+ * @head: the list whose entries are counted
+ */
+static inline size_t list_size(const struct list_head *head)
+{
+ size_t ret = 0;
+
+ for (struct list_head *curr = head->next; curr != head;
+ curr = curr->next)
+ ++ret;
+
+ return ret;
+}
+
/**
* list_entry - get the struct for this entry
* @ptr: the &struct list_head pointer.
@@ -310,6 +325,40 @@ static inline int list_empty(const struct list_head *head)
!list_entry_is_head(pos, head, member); \
pos = n, n = list_next_entry(n, member))
+/**
+ * list_for_each_entry_from - iterate over list of given type starting at a given node
+ * @pos: the type * to use as a loop cursor.
+ * @start: the node to start iterating at
+ * @head: the head for your list.
+ * @member: the name of the list_head within the struct.
+ */
+#define list_for_each_entry_from(pos, start, head, member) \
+ for (pos = list_entry(start, typeof(*pos), member); \
+ !list_entry_is_head(pos, head, member); \
+ pos = list_next_entry(pos, member))
+
+/**
+ * list_at_index - retrieve the entry at index i in O(n)
+ * @i: index of entry to retrieve.
+ * @head: the head for your list.
+ * @type: the type of the struct the entries are embedded in.
+ * @member: the name of the list_head within the struct.
+ */
+#define list_at_index(i, head, type, member) \
+ ({ \
+ type *__pos; \
+ size_t __counter = 0; \
+ list_for_each_entry(__pos, head, member) { \
+ if (__counter++ == i) \
+ break; \
+ if (__pos->member.next == head) { \
+ __pos = NULL; \
+ break; \
+ } \
+ } \
+ __pos; \
+ })
+
/*
* Double linked lists with a single pointer list head.
* Mostly useful for hash tables where the two pointer list head is
--
2.39.5On Mon, Oct 28, 2024 at 04:49:40AM +0100, Ole Schuerks wrote:
> +/**
> + * list_size - counts the number of entries in a list
> + * @head: the list whose entries are counted
> + */
> +static inline size_t list_size(const struct list_head *head)
> +{
> + size_t ret = 0;
> +
> + for (struct list_head *curr = head->next; curr != head;
> + curr = curr->next)
> + ++ret;
> +
> + return ret;
What's wrong with list_count_nodes()?
> @@ -310,6 +325,40 @@ static inline int list_empty(const struct list_head *head)
> !list_entry_is_head(pos, head, member); \
> pos = n, n = list_next_entry(n, member))
>
> +/**
> + * list_for_each_entry_from - iterate over list of given type starting at a given node
> + * @pos: the type * to use as a loop cursor.
> + * @start: the node to start iterating at
> + * @head: the head for your list.
> + * @member: the name of the list_head within the struct.
> + */
> +#define list_for_each_entry_from(pos, start, head, member) \
> + for (pos = list_entry(start, typeof(*pos), member); \
> + !list_entry_is_head(pos, head, member); \
> + pos = list_next_entry(pos, member))
list_for_each_entry_from() exists on my tree on linux-next added
through commit e229c2fb3370a ("[LIST]: Introduce
list_for_each_entry_from") since v2.6.17, so since 2006.
> +/**
> + * list_at_index - retrieve the entry at index i in O(n)
> + * @i: index of entry to retrieve.
> + * @head: the head for your list.
> + * @type: the type of the struct the entries are embedded in.
> + * @member: the name of the list_head within the struct.
> + */
> +#define list_at_index(i, head, type, member) \
> + ({ \
> + type *__pos; \
> + size_t __counter = 0; \
> + list_for_each_entry(__pos, head, member) { \
> + if (__counter++ == i) \
> + break; \
> + if (__pos->member.next == head) { \
> + __pos = NULL; \
> + break; \
> + } \
> + } \
> + __pos; \
> + })
> +
Seems like the only thing being added. I'd just keep thsi internal
to your code for now, and later if we really want we can add this
as a generic helper. If you really want this on list.h I'd recommend
to find a few users of this already in kernel and generalize the common
thing to use it first and add it that way. Then you separate *that*
patches series from this one, and address that first, and address
the addition then as a seprate patch series.
If you keep it to the tool itself, just change the namespace to be not
be as generically named of course.
Luis
> What's wrong with list_count_nodes()?
> list_for_each_entry_from() exists on my tree on linux-next added
> through commit e229c2fb3370a ("[LIST]: Introduce
> list_for_each_entry_from") since v2.6.17, so since 2006.
These macros only exist in include/linux/list.h, not in
scripts/include/list.h. My assumption was that the build system should only
use scripts/include/list.h.
> I'd just keep thsi internal to your code for now, and later if we really
> want we can add this as a generic helper.
Alright, the additions will be internals in v7.
Best regards,
Ole Schuerks
On Mon, Dec 09, 2024 at 02:00:19AM +0100, Ole Schuerks wrote:
> > What's wrong with list_count_nodes()?
>
> > list_for_each_entry_from() exists on my tree on linux-next added
> > through commit e229c2fb3370a ("[LIST]: Introduce
> > list_for_each_entry_from") since v2.6.17, so since 2006.
>
> These macros only exist in include/linux/list.h, not in
> scripts/include/list.h. My assumption was that the build system should only
> use scripts/include/list.h.
We can update scripts/include/list.h from include/linux/list.h. So just
say, bleh blah exists in bleh bleh bleh.
Luis
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