Re: [PATCH v6 03/13] vpci: move lock outside of struct vpci

[Jan Beulich <jbeulich@xxxxxxxx>]

On 07.02.2022 12:08, Oleksandr Andrushchenko wrote:
> 1. vpci_{read|write} are not protected with pcidevs_lock and can run in
> parallel with pci_remove_device which can remove pdev after vpci_{read|write}
> acquired the pdev pointer. This may lead to a fail due to pdev dereference.
> 
> So, to protect pdev dereference vpci_{read|write} must also use pdevs_lock.

I think this is not the only place where there is a theoretical race
against pci_remove_device(). I would recommend to separate the
overall situation with pcidevs_lock from the issue here. I don't view
it as an option to acquire pcidevs_lock in vpci_{read,write}(). If
anything, we need proper refcounting of PCI devices (at which point
likely a number of lock uses can go away).

Jan