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Re: [PATCH 3/4] vpci: shrink critical section in vpci_{read/write}


  • To: Oleksandr Andrushchenko <Oleksandr_Andrushchenko@xxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Wed, 2 Feb 2022 10:45:36 +0100
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  • Cc: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, "julien@xxxxxxx" <julien@xxxxxxx>, "sstabellini@xxxxxxxxxx" <sstabellini@xxxxxxxxxx>, Oleksandr Tyshchenko <Oleksandr_Tyshchenko@xxxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, "george.dunlap@xxxxxxxxxx" <george.dunlap@xxxxxxxxxx>, "paul@xxxxxxx" <paul@xxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Rahul Singh <rahul.singh@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
  • Delivery-date: Wed, 02 Feb 2022 09:45:45 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 02.02.2022 10:38, Oleksandr Andrushchenko wrote:
> On 02.02.22 11:05, Jan Beulich wrote:
>> On 02.02.2022 09:44, Roger Pau Monné wrote:
>>> On Tue, Feb 01, 2022 at 06:25:07PM +0200, Oleksandr Andrushchenko wrote:
>>>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
>> Oleksandr, can you please clarify authorship here? The rule of thumb is
>> that From: matches ...
>>
>>>> Shrink critical section in vpci_{read/write} as racing calls to
>>>> vpci_{read,write}_hw() shouldn't be a problem. Those are just wrappers
>>>> around pci_conf_{read,write} functions, and the required locking (in
>>>> case of using the IO ports) is already taken care in pci_conf_{read,write}.
>>>>
>>>> Please note, that we anyways split 64bit writes into two 32bit ones
>>>> without taking the lock for the whole duration of the access, so it is
>>>> possible to see a partially updated state as a result of a 64bit write:
>>>> the PCI(e) specification don't seem to specify whether the ECAM is allowed
>>>> to split memory transactions into multiple Configuration Requests and
>>>> whether those could then interleave with requests from a different CPU.
>>>>
>>>> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
>>>> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
>> ... the first S-o-b, as these are expected to be in chronological
>> order.
> Well, I was not sure here: the idea and the original code belongs
> to Roger and it was a part of a dedicated other patch. So, technically,
> this patch didn't exist before and Roger hasn't created it (the patch).
> So, this is why I'm in doubt here: should I change the authorship
> to Roger's? I had no means to offend anyone here nor I pretend
> for the authorship in any form.

My personal view on it is that if you've broken this out of a larger
patch coming from Roger, then he should be named as the author.

Jan




 


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