Re: nft_rhash_walk, rhashtable and resize event

Hi Herbert,

On Sat, Sep 16, 2023 at 11:37:51AM +0800, Herbert Xu wrote:

On Fri, Sep 15, 2023 at 10:05:06AM -0400, Alexander Aring wrote:

quoted

My question is here? Is that allowed to do because a resize event may
change the order how to iterate over a rhashtable.

Walking over an rhashtable should be a last resort.  There is
no guarantee of stability.

If you skip entries after a resize then you may miss entries.

One more question: this walk might miss entries but may it also
duplicate the same entries?

If you want a stable walk, allocate an extra 8 bytes and use
a linked list.

I will work on a patch to update netfilter clients for this code to
use a rcu linked list.

Thanks.