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

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Message-ID: <d3f16f0a-cc05-a6f1-17cb-2649b5ab42c8@gmx.de>
Date:   Thu, 28 Jul 2022 17:45:42 +0200
From:   Lino Sanfilippo <LinoSanfilippo@....de>
To:     Jarkko Sakkinen <jarkko@...nel.org>
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 28.07.22 10:15, Jarkko Sakkinen wrote:
> 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?
>

Sure, that should not be too difficult to do. I will implement this for the next version.

Regards,
Lino