linux-kernel - Re: [tpmdd-devel] [PATCH 6/6] tpm2: add session handle context saving and restoring to the space code

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Message-ID: <1486753935.2502.35.camel@HansenPartnership.com>
Date:   Fri, 10 Feb 2017 11:12:15 -0800
From:   James Bottomley <James.Bottomley@...senPartnership.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     open list <linux-kernel@...r.kernel.org>,
        linux-security-module@...r.kernel.org,
        tpmdd-devel@...ts.sourceforge.net
Subject: Re: [tpmdd-devel] [PATCH 6/6] tpm2: add session handle context
 saving and restoring to the space code

On Fri, 2017-02-10 at 21:10 +0200, Jarkko Sakkinen wrote:
> On Fri, Feb 10, 2017 at 08:17:11AM -0800, James Bottomley wrote:
> > On Fri, 2017-02-10 at 14:32 +0200, Jarkko Sakkinen wrote:
> > > On Wed, Feb 08, 2017 at 01:07:08PM +0200, Jarkko Sakkinen wrote:
> > > > From: James Bottomley <James.Bottomley@...senPartnership.com>
> > [...] 
> > > > +static int tpm2_session_add(struct tpm_chip *chip, u32 handle)
> > > > +{
> > > > +	struct tpm_space *space = &chip->work_space;
> > > > +	int i;
> > > > +
> > > > +	for (i = 0; i < ARRAY_SIZE(space->session_tbl); i++)
> > > > +		if (space->session_tbl[i] == 0)
> > > > +			break;
> > > > +	if (i == ARRAY_SIZE(space->session_tbl)) {
> > > > +		dev_err(&chip->dev, "out of session slots\n");
> > > 
> > > This really should be dev_dbg.
> > 
> > This was my reply to the comment the last time:
> > 
> >     I can do that, but I think this should be higher than debug. 
> >  If
> >     this trips, something an application was doing will fail with a
> > non
> >     TPM error and someone may wish to investigate why.  Having a
> > kernel
> >     message would help with that (but they won't see it if it's
> > debug).
> > 
> >     I'm also leaning towards the idea that we should actually have
> > one
> >     more _tbl slot than we know the TPM does, so that if someone
> > goes
> >     over it's the TPM that gives them a real TPM out of memory
> > error
> >     rather than the space code returning -ENOMEM.
> > 
> >     If you agree, I think it should be four for both sessions_tbl
> > and
> >     context_tbl.
> > 
> > So I really don't think it should be debug.  Could we compromise on
> > dev_info?
> > 
> > James
> 
> Oops, I'm sorry about that. I use the release chaos as an excuse :-)
> I would lower it to dev_warn().

That works.  Do you want me to resend the patch?

James