linux-kernel - Re: [PATCH 01/10] crypto: aead - allow to allocate AEAD requests on the stack

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Date:   Sat, 5 May 2018 19:17:34 +0200
From:   'Antoine Tenart' <antoine.tenart@...tlin.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>
Cc:     'Antoine Tenart' <antoine.tenart@...tlin.com>,
        David Laight <David.Laight@...lab.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "thomas.petazzoni@...tlin.com" <thomas.petazzoni@...tlin.com>,
        "maxime.chevallier@...tlin.com" <maxime.chevallier@...tlin.com>,
        "gregory.clement@...tlin.com" <gregory.clement@...tlin.com>,
        "miquel.raynal@...tlin.com" <miquel.raynal@...tlin.com>,
        "nadavh@...vell.com" <nadavh@...vell.com>,
        "oferh@...vell.com" <oferh@...vell.com>,
        "igall@...vell.com" <igall@...vell.com>
Subject: Re: [PATCH 01/10] crypto: aead - allow to allocate AEAD requests on
 the stack

Hi Herbert,

On Sat, May 05, 2018 at 02:18:55PM +0800, Herbert Xu wrote:
> On Fri, May 04, 2018 at 09:18:41AM +0200, 'Antoine Tenart' wrote:
> >
> > In this driver we need to perform in certain cases an invalidation,
> > which is done thanks to invalidation requests. To do this we create
> > dummy requests, using SKCIPHER_REQUEST_ON_STACK and
> > AHASH_REQUEST_ON_STACK for ciphers and hashes. So when adding the AEAD
> > algs support, in patch 8/10, AEAD_REQUEST_ON_STACK is used for the same
> > reason.
> > 
> > Should we allocate this in a different way?
> 
> These are not uses intended for the ON_STACK macros.  They were
> only ever meant for existing users of the synchonous crypto API.

OK, I see.

> I would suggest either allocating a new request on the spot or if
> that is not convenient, pre-allocating it in the cra_init function.

Or we could have similar macros in the driver: we wouldn't have VLAs
since it would be driver specific.

Thanks!
Antoine

-- 
Antoine Ténart, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com