Re: [PATCH net-next 1/2] net: store netdevs in an xarray

[Paolo Abeni <pabeni@redhat.com>]

On Mon, 2023-07-24 at 08:41 -0700, Jakub Kicinski wrote:
> On Mon, 24 Jul 2023 10:18:04 +0200 Paolo Abeni wrote:
> > A possibly dumb question: why using an xarray over a plain list?
> 
> We need to drop the lock during the walk. 

I should have looked more closely to patch 2/2.

> So for a list we'd need 
> to either 
>  - add explicit iteration "cursor" or 

Would a cursor require acquiring a netdev reference? If so it looks
problematic (an evil/buggy userspace could keep such reference held for
an unbounded amount of time).

I agree xarray looks a better solution.

I still have some minor doubts WRT the 'missed device' scenario you
described in the commit message. What if the user-space is doing
'create the new one before deleting the old one' with the assumption
that at least one of old/new is always reported in dumps? Is that a too
bold assumption?

> I was measuring it to find out if we can delete the hash table without
> anyone noticing, but it's not really the motivation.

Understood. I though about rhashtable with the opposite assumption :)
So no need to discuss such option further, I guess.

Cheers,

Paolo