Linux Ethernet Bridging - Mar 2017 - [Bridge] [PATCH 07/17] net: convert sock.sk_refcnt from atomic_t to refcount_t

From: Kees Cook <keescook at chromium.org>
Date: Thu, 16 Mar 2017 11:38:25 -0600
> I am, of course, biased, but I think the evidence of actual
> refcounting attacks outweighs the theoretical performance cost of
> these changes.
This is not theoretical at all.

We count the nanoseconds that every packet takes to get processed and
you are adding quite a bit.

I understand your point of view, but this is knowingly going to add
performance regressions to the networking code.

> From: Kees Cook <keescook at chromium.org>
> Date: Thu, 16 Mar 2017 11:38:25 -0600
> 
> > I am, of course, biased, but I think the evidence of actual
> > refcounting attacks outweighs the theoretical performance cost of
> > these changes.
> 
> This is not theoretical at all.
> 
> We count the nanoseconds that every packet takes to get processed and
> you are adding quite a bit.
> 
> I understand your point of view, but this is knowingly going to add
> performance regressions to the networking code.
Should we then first measure the actual numbers to understand what we are
talking here about?
I would be glad to do it if you suggest what is the correct way to do
measurements here to actually reflect the real life use cases.

Best Regards,
Elena.