linux-kernel - Re: [PATCH] hw_random: Improve description of the ->read() interface

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Message-ID: <20160824131324.GB3850@gondor.apana.org.au>
Date:   Wed, 24 Aug 2016 21:13:24 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Daniel Thompson <daniel.thompson@...aro.org>
Cc:     Matt Mackall <mpm@...enic.com>, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org, patches@...aro.org,
        linaro-kernel@...ts.linaro.org,
        LABBE Corentin <clabbe.montjoie@...il.com>,
        PrasannaKumar Muralidharan <prasannatsmkumar@...il.com>
Subject: Re: [PATCH] hw_random: Improve description of the ->read() interface

On Thu, Aug 18, 2016 at 01:37:21PM +0100, Daniel Thompson wrote:
> Currently, very few RNG drivers support single byte reads using the
> ->read() interface. Of the 14 drivers in drivers/char/hw_random that
> support this interface only three of these actually support max == 1.
> The other behaviours vary between return 0, return 2, return 4 and return
> -EIO).
> 
> This is not a problem in practice because the core hw_random code never
> performs a read shorter than 16 bytes. The documentation for this function
> already contrains the alignment of the buffer pointer, so let's also
> guarantee that the buffer is at least as large as its alignment.
> 
> This constraint is intended to be the weakest guarantee neccessary to
> allow driver writers to safely simplify their code.
> 
> Signed-off-by: Daniel Thompson <daniel.thompson@...aro.org>

Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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