Re: [PATCH 09/24] rcu/tree: cache specified number of objects

Uladzislau Rezki
2020-05-04T19:51:35Z

> > > Since we don't care about traversing backwards, isn't it better to use llist
> > > for this usecase?
> > >
> > > I think Vlad is using locking as we're also tracking the size of the llist to
> > > know when to free pages. This tracking could suffer from the lost-update
> > > problem without any locking, 2 lockless llist_add happened simulatenously.
> > >
> > > Also if list_head is used, it will take more space and still use locking.
> >
> > Indeed, it would be best to use a non-concurrent singly linked list.
>
> Ok cool :-)
>
> Is it safe to say something like the following is ruled out? ;-) :-D
> #define kfree_rcu_list_add llist_add
>
In that case i think it is better just to add a comment about using
llist_head. To state that it used as a singular list to save space
and the access is synchronized by the lock :)

IMHO.

--
Vlad Rezki