linux-kernel - Re: [PATCH 1/3 RESEND] tpm: add longer timeouts for creation commands.

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Message-ID: <20180306080159.GC3624@linux.intel.com>
Date:   Tue, 6 Mar 2018 10:02:15 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     "Winkler, Tomas" <tomas.winkler@...el.com>
Cc:     Jason Gunthorpe <jgg@...pe.ca>,
        "Usyskin, Alexander" <alexander.usyskin@...el.com>,
        "linux-integrity@...r.kernel.org" <linux-integrity@...r.kernel.org>,
        "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3 RESEND] tpm: add longer timeouts for creation
 commands.

On Mon, Mar 05, 2018 at 06:04:56PM +0000, Winkler, Tomas wrote:
> > 
> > On Mon, Mar 05, 2018 at 01:09:09PM +0000, Winkler, Tomas wrote:
> > > > enum tpm_duration {
> > > > 	TPM_DURATION_DEFAULT = 2000,
> > > > 	TPM_DURATION_LONG = 300000,
> > > > };
> > > >
> > > How is this aligned with the spec PTP spec?
> > 
> > For TPM 2.0 that spec only partially defines durations for CCs and thus our
> > look up table is already kind "flakky". In a sense that the default duration is
> > upper limit for spec defined durations.
> 
> The timeouts for LONG and MEDIUM is defined by the  PTP spec,  we need to maintain those as those effect the system.
> The UNDEFINED and LONG LONG is the implementation choice we driver from empirical data we have so far.

Where can be get this empirical data?

You are not only adding 30s delay but also turning the 2s delay to 12s
delay.

IMHO we could very well use PTP LONG for all commands as the timeout.
Why that would not work?

/Jarkko