linux-kernel - Re: [PATCH v3 3/6] crypto: Add Qcom prng driver

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Message-ID: <20180704041059.GT22377@vkoul-mobl>
Date:   Wed, 4 Jul 2018 09:40:59 +0530
From:   Vinod <vkoul@...nel.org>
To:     Stephan Mueller <smueller@...onox.de>
Cc:     linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Matt Mackall <mpm@...enic.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-msm@...r.kernel.org, Stephen Boyd <swboyd@...omium.org>,
        Timur Tabi <timur@...eaurora.org>
Subject: Re: [PATCH v3 3/6] crypto: Add Qcom prng driver

Hi Stephan,

On 03-07-18, 15:28, Stephan Mueller wrote:
> Am Dienstag, 3. Juli 2018, 08:04:31 CEST schrieb Vinod Koul:
> > +static int qcom_rng_read(struct qcom_rng *rng, void *data, size_t max)
> > +{
> > +	size_t currsize = 0;
> > +	u32 *retdata = data;
> 
> How can you be sure that this cast is appropriate? I.e. how is it guaranteed 
> that data is 4-byte aligned?

While reading we check the alignment:

               /* make sure we stay on 32bit boundary */
               if ((max - currsize) < WORD_SZ)
                       break;

> Also, the data variable in qcom_rng_generate is a u8 -- shouldn't this type be 
> used instead of a void?

That does make sense to me. IIRC the read is for a byte. I will check
this and update it

Thanks for the quick review
-- 
~Vinod