linux-kernel - Re: [PATCH 0/5] crypto: caam - avoid allocating memory at crypto request runtime

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Date:   Thu, 3 Dec 2020 09:34:08 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     "Iuliana Prodan (OSS)" <iuliana.prodan@....nxp.com>
Cc:     Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Horia Geanta <horia.geanta@....com>,
        Aymen Sghaier <aymen.sghaier@....com>,
        Silvano Di Ninno <silvano.dininno@....com>,
        Franck Lenormand <franck.lenormand@....com>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-imx <linux-imx@....com>,
        Iuliana Prodan <iuliana.prodan@....com>
Subject: Re: [PATCH 0/5] crypto: caam - avoid allocating memory at crypto
 request runtime

On Thu, 3 Dec 2020 at 02:35, Iuliana Prodan (OSS)
<iuliana.prodan@....nxp.com> wrote:
>
> From: Iuliana Prodan <iuliana.prodan@....com>
>
> This series removes CRYPTO_ALG_ALLOCATES_MEMORY flag and
> allocates the memory needed by the driver, to fulfil a
> request, within the crypto request object.
> The extra size needed for base extended descriptor, hw
> descriptor commands and link tables is added to the reqsize
> field that indicates how much memory could be needed per request.
>
> CRYPTO_ALG_ALLOCATES_MEMORY flag is limited only to
> dm-crypt use-cases, which seems to be 4 entries maximum.
> Therefore in reqsize we allocate memory for maximum 4 entries
> for src and 4 for dst, aligned.
> If the driver needs more than the 4 entries maximum, the memory
> is dynamically allocated, at runtime.
>

I'm confused. So the driver does allocate memory in some cases, right?
So why is it justified to remove CRYPTO_ALG_ALLOCATES_MEMORY?

> Iuliana Prodan (5):
>   crypto: caam/jr - avoid allocating memory at crypto request runtime
>     for skcipher
>   crypto: caam/jr - avoid allocating memory at crypto request runtime
>     for aead
>   crypto: caam/jr - avoid allocating memory at crypto request runtime
>     fost hash
>   crypto: caam/qi - avoid allocating memory at crypto request runtime
>   crypto: caam/qi2 - avoid allocating memory at crypto request runtime
>
>  drivers/crypto/caam/caamalg.c     | 141 +++++++---
>  drivers/crypto/caam/caamalg_qi.c  | 134 ++++++----
>  drivers/crypto/caam/caamalg_qi2.c | 415 ++++++++++++++++++++----------
>  drivers/crypto/caam/caamalg_qi2.h |   6 +
>  drivers/crypto/caam/caamhash.c    |  77 ++++--
>  5 files changed, 538 insertions(+), 235 deletions(-)
>
> --
> 2.17.1
>