netdev - Re: rhashtable: Move hash_rnd into bucket

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Message-ID: <20150309222105.GA12158@gondor.apana.org.au>
Date:	Tue, 10 Mar 2015 09:21:05 +1100
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Daniel Borkmann <daniel@...earbox.net>
Cc:	David Miller <davem@...emloft.net>, tgraf@...g.ch,
	netdev@...r.kernel.org
Subject: Re: rhashtable: Move hash_rnd into bucket_table

On Mon, Mar 09, 2015 at 05:26:52PM +0100, Daniel Borkmann wrote:
> 
> I believe the original purpose was to have reproduceability, but
> yeah, there are no users of it currently.

If anyone ever needed that we could always provide a way to set
the random value, through a rehash.
 
> Have you tested this patch? ;-)

Clearly not :)

> If I see this correctly, the first time you shrink or expand, your hash_rnd
> from then onwards will constantly be 0.
> 
> You need to copy over the above old hash_rnd to the new one from the newly
> allocated tbl. So, bucket_table_alloc() needs a change as well. Of course,
> with rehashing, the get_random_bytes() would directly move there.

Yes it should copy them.  I've fixed in my tree now and it actually
works!

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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