On Tue, Jun 10, 2025 at 04:24:13PM +0200, Claudio Jeker wrote:
> On Tue, Jun 10, 2025 at 08:02:02AM -0600, Theo de Raadt wrote:
> > Stefan Fritsch <sf@sfritsch.de> wrote:
> > 
> > > Diff below. Does one need to do something special when changing the sysctl 
> > > structs? Comments, opinions?
> > 
> > It will be a subtle and small ABI breakage between the kernel and the
> > netstat binary, but I don't see anything else actually looking at the
> > fields in the structure.  It is extremely unlikely anything in ports
> > looks at any fields, and will notice their positions have changed.
>  
> I think best would be to just replace the fields with pads. There is some
> rather bad code in golang and rust. We may be lucky and nobody pulls those
> sysctl structs out yet but e.g. node_exporter is very sloppy since
> everyone thinks the ABI will never change.

The ABI has changed a few releases ago when I added the defrag and
prepend counters at the end of the struct.  So software that epxects
the old struct from 2002 should be broken anyway.  These fields
look very BSD specific to me.  I would just remove them and don't
bother with padding.

Incrementing the fail counter is obvious.  This chunk is OK bluhm.

Our stack has not use mbufs drain for a long time.  So removing the
counter seems reasonable unless someone wants this feature back.

The wait counter would be interesting.  Accounting whenever
m_get(M_WAIT) actually has to sleep, could help to indentify
performance bottlenecks.  But only pool knows about sleeps.  Problem
is to propagate this information from pl_sleep() to mbuf layer with
a clean API.  Or should we add a pool counter for that?

bluhm