netdev - Re: nft hash set expansion problem

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Message-ID: <54D8C7D0.9030803@akamai.com>
Date:	Mon, 09 Feb 2015 08:44:32 -0600
From:	Josh Hunt <johunt@...mai.com>
To:	Daniel Borkmann <daniel@...earbox.net>
CC:	Thomas Graf <tgraf@...g.ch>,
	Pablo Neira Ayuso <pablo@...filter.org>, kaber@...sh.net,
	netdev@...r.kernel.org, netfilter-devel@...r.kernel.org
Subject: Re: nft hash set expansion problem

On 02/08/2015 04:43 PM, Daniel Borkmann wrote:
> On 02/08/2015 08:38 PM, Josh Hunt wrote:
>> Nft hash sets are unable to expand past the initial # of buckets. This
>> is b/c nft hash sets don't define the max_shift parameter and so
>> rht_grow_above_75():
> ...
>> diff --git a/lib/rhashtable.c b/lib/rhashtable.c
>> index e96fc00..2c51617 100644
>> --- a/lib/rhashtable.c
>> +++ b/lib/rhashtable.c
>> @@ -250,7 +250,7 @@ bool rht_grow_above_75(const struct rhashtable
>> *ht, size_t new_size)
>>   {
>>          /* Expand table when exceeding 75% load */
>>          return atomic_read(&ht->nelems) > (new_size / 4 * 3) &&
>> -              (ht->p.max_shift && atomic_read(&ht->shift) <
>> ht->p.max_shift);
>> +              (ht->p.max_shift ? atomic_read(&ht->shift) <
>> ht->p.max_shift : 1);
>>   }
>>   EXPORT_SYMBOL_GPL(rht_grow_above_75);
>
> This seems not correct as we want to have an upper limit for
> rhashtable expansions. It's better to define a max_shift for
> nftables, instead.

Thanks Daniel that's what I wanted to know. I'll fix this on the 
nft_hash side.

Josh
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