Re: [PATCH v9 02/16] vpci: use per-domain PCI lock to protect vpci structure

[Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>]

Hi Roger,

Roger Pau Monné <roger.pau@citrix.com> writes:

> On Tue, Aug 29, 2023 at 11:19:42PM +0000, Volodymyr Babchuk wrote:
>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>> 
>> Use a previously introduced per-domain read/write lock to check
>> whether vpci is present, so we are sure there are no accesses to the
>> contents of the vpci struct if not. This lock can be used (and in a
>> few cases is used right away) so that vpci removal can be performed
>> while holding the lock in write mode. Previously such removal could
>> race with vpci_read for example.
>> 
>> When taking both d->pci_lock and pdev->vpci->lock they are should be
>
> When taking both d->pci_lock and pdev->vpci->lock the order should be
> ...
>

>> taken in this exact order: d->pci_lock then pdev->vpci->lock to avoid
>> possible deadlock situations.
>>

Will it be better to write like this:

"When taking both d->pci_lock and pdev->vpci->lock, they should be
taken in this exact order: d->pci_lock then pdev->vpci->lock to avoid
possible deadlock situations."

?

I am asking because your suggestion leads to "When taking both
d->pci_lock and pdev->vpci->lock the order should be taken in this exact
order: ... "

[...]

As for other comments, I am taking into account your, Jan's and Stewart's
comments and reworking this patch.

-- 
WBR, Volodymyr