netdev - Re: [PATCH v7 15/16] openvswitch: use new hashtable implementation

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Message-ID: <20121029182209.GB4066@htj.dyndns.org>
Date:	Mon, 29 Oct 2012 11:22:09 -0700
From:	Tejun Heo <tj@...nel.org>
To:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc:	Sasha Levin <levinsasha928@...il.com>,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
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Subject: Re: [PATCH v7 15/16] openvswitch: use new hashtable implementation

Hello,

On Mon, Oct 29, 2012 at 02:16:48PM -0400, Mathieu Desnoyers wrote:
> This is just one example in an attempt to show why different hash table
> users may have different constraints: for a hash table entirely
> populated by keys generated internally by the kernel, a random seed
> might not be required, but for cases where values are fed by user-space
> and from the NIC, I would argue that flexibility to implement a
> randomizable hash function beats implementation simplicity any time.
> 
> And you could keep the basic use-case simple by providing hints to the
> hash_32()/hash_64()/hash_ulong() helpers in comments.

If all you need is throwing in a salt value to avoid attacks, can't
you just do that from caller side?  Scrambling the key before feeding
it into hash_*() should work, no?

Thanks.

-- 
tejun
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