Re: [PATCH net-next v3] netdev: avoid skipping objects on race with device disappearance

[Jakub Kicinski <kuba@kernel.org>]

On Fri, 4 Sep 2026 01:08:11 +0200 Eric Dumazet wrote:
> On Fri, Sep 4, 2026 at 12:11 AM Jakub Kicinski <kuba@kernel.org> wrote:
> > If the currently dumped device disappears while we were mid-dump
> > we will get the next device without resetting the sub-object ID.
> > This is quite unlikely, it was reported by an AI tool not a real
> > user. Let's fix it for better dump consistency.
> >
> > We only intend to cover the case where device A disappears
> > and we skip over sub-objects of device B which was stable (B existed
> > before and after the dump). We don't intend to provide stable
> > results for any device that gets created or deleted during
> > the dump.  
> 
> SGTM. Note an ifindex can be reused by a new device, we might need to
> add a dev->dev_cookie
> (64bit unique number) like we have for sockets and netns to also catch
> this in the future.

That would work. IDK if it's worth the LoC, tho. The existing workaround
is to subscribe to NEW/DEL notifications, do the dump, and then "apply"
the notifications. The notifications carry correct state of the objects
which were modified, the dump has to cover only "stable" objects.
At least that's the excuse I'm telling myself :)