netdev - Re: [PATCH v4] mac80211: move extra crypto data off the stack

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Message-ID: <1476710169.315.1.camel@sipsolutions.net>
Date:   Mon, 17 Oct 2016 15:16:09 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     "<linux-wireless@...r.kernel.org>" <linux-wireless@...r.kernel.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        "<netdev@...r.kernel.org>" <netdev@...r.kernel.org>,
        Herbert Xu <herbert@...dor.apana.org.au>
Subject: Re: [PATCH v4] mac80211: move extra crypto data off the stack

On Mon, 2016-10-17 at 14:06 +0100, Ard Biesheuvel wrote:
> 
> Actually, while I think it will be worthwhile going forward to
> implement such an 'auxiliary data' feature in a generic way, I still
> think we should address the issue at hand without too much
> complication.
> 
> If we pedal back to the version of 'mac80211: move struct aead_req
> off the stack' that uses kzalloc() instead of aead_request_alloc(),
> we can simply add some space for aad[] and/or zero[], and get rid of
> the kmem cache entirely.
> 
> If you're past this point already, i won't bother but otherwise I can
> rework 'mac80211: move struct aead_req off the stack' so that the
> other patch is no longer required (and IIRC, this is actually
> something you proposed yourself a couple of iterations ago?)

Yes, I did consider that.

It makes some sense, and I guess the extra memcpy() would be cheaper
than the extra alloc?

I'd happily use that instead of the combination of my two patches. The
aead_request_alloc() is just a simple inline anyway, so no real problem
not using it.

johannes