linux-kernel - Re: [PATCH] tpm: vtpm_proxy: Do not run tpm2

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Message-Id: <cf746443-5ef5-211f-6b62-a5d4d66e27fd@linux.vnet.ibm.com>
Date:   Thu, 25 May 2017 16:54:01 -0400
From:   Stefan Berger <stefanb@...ux.vnet.ibm.com>
To:     Jason Gunthorpe <jgunthorpe@...idianresearch.com>
Cc:     jarkko.sakkinen@...ux.intel.com, tpmdd-devel@...ts.sourceforge.net,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tpm: vtpm_proxy: Do not run tpm2_shutdown

On 05/25/2017 04:44 PM, Jason Gunthorpe wrote:
> On Thu, May 25, 2017 at 04:32:50PM -0400, Stefan Berger wrote:
>
>> It doesn't hang. Everything is torn down immediately. What is primarily
>> annoying are these two log messages:
>> tpm tpm0: tpm_transmit: tpm_send: error -32
>> tpm tpm0: transmit returned -32 while stopping the TPM
> I think it would be better to change the core to suppress that logging
> if the FD is closed.

This particular command will never reach anyone listening on the proxy's 
file descriptor since the tear-down only begins when the front- and 
backend are closed.
The logging happens somewhere else than where the error occurs. What is 
the best way to suppress the logging? Remove it entirely  -- probably 
not. Return a special error code that doesn't get logged? Return a 2nd 
parameter that indicates this condition? It's not clear to me. Why not 
just prevent the command from being sent if it will never reach its 
intended destination ?

   Stefan

>
> Jason
>