From: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Subject: Re: [PATCH] tpm: Move Linux RNG connection to hwrng
Date: Wed, 25 Oct 2017 20:55:33 +0530
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 <20171025151859.GB15557@obsidianresearch.com>
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Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Stefan Berger <stefanb@linux.vnet.ibm.com>,
        linux-integrity@vger.kernel.org,
        David Howells <dhowells@redhat.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
        open list <linux-kernel@vger.kernel.org>,
        linux-security-module@vger.kernel.org,
        "open list:KEYS-TRUSTED" <keyrings@vger.kernel.org>,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
        <linux-crypto@vger.kernel.org>,
        James Morris <james.l.morris@oracle.com>,
        Matt Mackall <mpm@selenic.com>,
        David Safford <safford@us.ibm.com>,
        Mimi Zohar <zohar@linux.vnet.ibm.com>,
        "Serge E. Hallyn" <serge@hallyn.com>
To: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
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Hi Jason,

On 25 October 2017 at 20:48, Jason Gunthorpe
<jgunthorpe@obsidianresearch.com> wrote:
> On Wed, Oct 25, 2017 at 08:15:09PM +0530, PrasannaKumar Muralidharan
> wrote:
>
>> > +static int tpm_add_hwrng(struct tpm_chip *chip)
>> > +{
>> > +       if (!IS_ENABLED(CONFIG_HW_RANDOM_TPM))
>> > +               return 0;
>>
>> Can #ifndef CONFIG_HW_RANDOM_TPM be used instead? That way an if
>> condition can be avoided.
>
> Generally speaking IS_ENABLED is prefered over #ifdef as it reduces the
> set of compilation combinations.

Oh okay. No issues then.

Regards,
PrasannaKumar