From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Subject: Re: [PATCH v2] tpm: use struct tpm_chip for tpm_chip_find_get()
Date: Thu, 26 Oct 2017 12:54:30 +0200
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Cc: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>,
        linux-integrity@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        Matt Mackall <mpm@selenic.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Peter Huewe <peterhuewe@gmx.de>,
        Marcel Selhorst <tpmdd@selhorst.net>,
        Mimi Zohar <zohar@linux.vnet.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
        James Morris <james.l.morris@oracle.com>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        David Safford <safford@us.ibm.com>,
        David Howells <dhowells@redhat.com>,
        Jerry Snitselaar <jsnitsel@redhat.com>,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
        <linux-crypto@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        "moderated list:TPM DEVICE DRIVER"
        <tpmdd-devel@lists.sourceforge.net>,
To: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
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On Wed, Oct 25, 2017 at 02:17:44PM -0600, Jason Gunthorpe wrote:
> On Wed, Oct 25, 2017 at 10:07:46PM +0200, Jarkko Sakkinen wrote:
> 
> > The id has a nice feature that it is unique for one boot cycle you can
> > even try to get a chip that has been deleted. It has the most stable
> > properties in the long run.
> 
> It isn't unique, we can re-use ids them via idr_alloc(). We should
> never use index inside the kernel.
> 
> > Address is a reusable identifier in one boot cycle.
> 
> It is invalid to pass in a chip for which the caller does not hold a
> kref, so address is the safest argument.
> 
> Jason

I'll buy this too (sending update today).

/Jarkko