On Mon, Sep 10, 2007 at 02:05:47PM +0200, Johannes Berg wrote:
> To implement the multicast list callback in mac80211 we need to
> do partial list iteration. Since I want to convert the interface
> list to an RCU list, I need a new list walking primitive:
> list_for_each_entry_continue_rcu().
>
> Additional help text was provided by Paul McKenney.
Acked-by: Paul E. McKenney <[email protected]>
> Signed-off-by: Johannes Berg <[email protected]>
> Cc: [email protected]
> Cc: Paul E. McKenney <[email protected]>
>
> ---
> John, I don't know if you want to merge this or not. There's no clear
> list.h maintainer and this patch is requisite for the bugfix I'm going
> to send in a minute so it'd probably be best if this goes into the tree
> together.
> If you don't want to take it, however, I have no idea how to handle the
> situation :)
>
> include/linux/list.h | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> --- wireless-dev.orig/include/linux/list.h 2007-09-07 22:00:41.234425862 +0200
> +++ wireless-dev/include/linux/list.h 2007-09-07 22:05:08.184425862 +0200
> @@ -665,6 +665,32 @@ static inline void list_splice_init_rcu(
> prefetch(rcu_dereference((pos))->next), (pos) != (head); \
> (pos) = (pos)->next)
>
> +
> +/**
> + * list_for_each_entry_continue_rcu - continue iteration over rcu list
> + * @pos: the type * to use as a loop cursor.
> + * @head: the head for your list.
> + * @member: the name of the list_struct within the struct.
> + *
> + * Continue to iterate over rcu list of given type, continuing after
> + * the current position.
> + *
> + * This list-traversal primitive may safely run concurrently with
> + * the _rcu list-mutation primitives such as list_add_rcu()
> + * as long as the traversal is guarded by rcu_read_lock().
> + *
> + * Note that the caller is responsible for making sure that
> + * the element remains in place between the earlier iterator
> + * and this one. One way to do this is to ensure that
> + * both iterators are covered by the same rcu_read_lock(),
> + * while others involve reference counts, flags, or mutexes.
> + */
> +#define list_for_each_entry_continue_rcu(pos, head, member) \
> + for ((pos) = list_entry((pos)->member.next, typeof(*pos), member); \
> + prefetch(rcu_dereference((pos))->member.next), \
> + &pos->member != (head); \
> + (pos) = list_entry(pos->member.next, typeof(*pos), member))
> +
> /*
> * Double linked lists with a single pointer list head.
> * Mostly useful for hash tables where the two pointer list head is
>
>
-
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