linux-kernel - Re: [PATCH v7 07/10] tmp, tmp_tis: Implement usage counter for locality

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Message-ID: <YuJFuBFtImG/k+C0@kernel.org>
Date:   Thu, 28 Jul 2022 11:15:52 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Lino Sanfilippo <LinoSanfilippo@....de>
Cc:     peterhuewe@....de, jgg@...pe.ca, stefanb@...ux.vnet.ibm.com,
        linux@...ewoehner.de, linux-integrity@...r.kernel.org,
        linux-kernel@...r.kernel.org, l.sanfilippo@...bus.com,
        lukas@...ner.de, p.rosenberger@...bus.com
Subject: Re: [PATCH v7 07/10] tmp, tmp_tis: Implement usage counter for
 locality

On Wed, Jul 27, 2022 at 02:16:56PM +0200, Lino Sanfilippo wrote:
> 
> 
> On 11.07.22 04:50, Jarkko Sakkinen wrote:
> > On Mon, Jul 04, 2022 at 07:45:12PM +0200, Lino Sanfilippo wrote:
> >>
> >>
> >> On 01.07.22 01:29, Jarkko Sakkinen wrote:
> >>
> >>>
> >>> I'm kind of thinking that should tpm_tis_data have a lock for its
> >>> contents?
> >>
> >> Most of the tpm_tis_data structure elements are set once during init and
> >> then never changed but only read. So no need for locking for these. The
> >> exceptions I see are
> >>
> >> - flags
> >> - locality_count
> >> - locality
> >
> > I'd still go for single data struct lock, since this lock would
> > be taken in every transmit flow. It makes the whole thing easier
> > to maintain over time, and does not really affect scalability.
> >
> 
> This means switching to a complete new locking scheme which affects many
> parts of the TIS core code. It is also not directly related to what this patch series
> is about, namely activating the interrupts for TPM TIS.
> 
> I suggest to first finish polishing this series especially since there have
> only been minor issues in the last versions. Once the interrupts work we
> still can think of implementing another lock handling in a follow up series.

So what if you would use kref instead here?

On surface this looks like ad-hoc kref but I could wrong too (as always).

BR, Jarkko