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Re: [PATCH v4 1/2] drivers/misc: sysgenid: add system generation id driv
From: |
Michael S. Tsirkin |
Subject: |
Re: [PATCH v4 1/2] drivers/misc: sysgenid: add system generation id driver |
Date: |
Tue, 2 Feb 2021 09:32:50 -0500 |
On Wed, Jan 27, 2021 at 11:15:05PM +0100, Pavel Machek wrote:
> Hi!
>
> > - Solution
> >
> > The System Generation ID is a simple concept meant to alleviate the
> > issue by providing a monotonically increasing u32 counter that changes
> > each time the VM or container is restored from a snapshot.
>
> I'd make it u64.
>
> But as people explained, this has race problems that may be impossible
> to solve?
Well the read/write interface could be used in a safe way thinkably:
- application checks VM gen id
- application sends a transaction e.g. to database
- application re-checks VM gen id
- if id changed, application checks the database for duplicate
transactions
not sure how can the mmap interface be used safely.
Drop it for now?
> Best regards,
> Pavel
>
> --
> http://www.livejournal.com/~pavelmachek
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