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From:   NeilBrown <neilb@suse.com>
To:     Herbert Xu <herbert@gondor.apana.org.au>
Date:   Thu, 29 Mar 2018 12:13:24 +1100
Cc:     Thomas Graf <tgraf@suug.ch>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/6] rhashtable: allow a walk of the hash table without missing objects.
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References: <152210688405.11435.13010923693146415942.stgit@noble> <152210718430.11435.5761213978298714527.stgit@noble> <20180327155118.GB14001@gondor.apana.org.au> <87po3p421q.fsf@notabene.neil.brown.name> <20180328060734.GB16291@gondor.apana.org.au> <87a7us4qje.fsf@notabene.neil.brown.name> <20180328073023.GB17306@gondor.apana.org.au> <87zi2r3mve.fsf@notabene.neil.brown.name>
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On Thu, Mar 29 2018, NeilBrown wrote:

>
> How about storing the hash chains in order by object address?
> Then rhashtable_walk_start() can easily find it's place regardless of
> whether the old object was still present or not, using <= on the
> address.
> "Insert" would need to record an insert location and insert there rather
> than at the head of the chain.
> I might try coding that.

Unfortunately rhltables make this approach unworkable.
However while trying to write the code I found a bug :-(
I'll post a patch for the bug, and a patch to transparently make the
current interface more reliable when the caller keeps the current
object in the table.
I think this is sufficient for all current use-cases.

Thanks,
NeilBrown

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