Re: [Patch v2 net 1/2] netem: Fix skb duplication logic to prevent infinite loops

[Simon Horman <horms@kernel.org>]

On Tue, Jul 08, 2025 at 09:19:50AM -0400, Jamal Hadi Salim wrote:
> On Tue, Jul 8, 2025 at 9:18 AM Simon Horman <horms@kernel.org> wrote:
> >
> > On Mon, Jul 07, 2025 at 12:50:14PM -0700, Cong Wang wrote:
> > > This patch refines the packet duplication handling in netem_enqueue() to ensure
> > > that only newly cloned skbs are marked as duplicates. This prevents scenarios
> > > where nested netem qdiscs with 100% duplication could cause infinite loops of
> > > skb duplication.
> > >
> > > By ensuring the duplicate flag is properly managed, this patch maintains skb
> > > integrity and avoids excessive packet duplication in complex qdisc setups.
> > >
> > > Now we could also get rid of the ugly temporary overwrite of
> > > q->duplicate.
> > >
> > > Fixes: 0afb51e72855 ("[PKT_SCHED]: netem: reinsert for duplication")
> > > Reported-by: William Liu <will@willsroot.io>
> > > Reported-by: Savino Dicanosa <savy@syst3mfailure.io>
> > > Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
> >
> > Reviewed-by: Simon Horman <horms@kernel.org>
> 
> Simon,
> This patch wont work - see the sample config i presented.

Sorry, I convinced myself it would.
But it seems I was wrong.