Re: [PATCH net] net/sched: ets: use old 'nbands' while purging unused classes

[Davide Caratti <dcaratti@redhat.com>]

On Fri, Aug 08, 2025 at 03:15:13PM -0300, Victor Nogueira wrote:
> On 8/7/25 12:48, Davide Caratti wrote:

[...]
 
> > Fixes: 103406b38c60 ("net/sched: Always pass notifications when child class becomes empty")
> > Fixes: c062f2a0b04d ("net/sched: sch_ets: don't remove idle classes from the round-robin list")
> > Fixes: dcc68b4d8084 ("net: sch_ets: Add a new Qdisc")
> > Reported-by: Li Shuang <shuali@redhat.com>
> > Closes: https://issues.redhat.com/browse/RHEL-108026
> > Co-developed-by: Ivan Vecera <ivecera@redhat.com>
> > Signed-off-by: Ivan Vecera <ivecera@redhat.com>
> > Signed-off-by: Davide Caratti <dcaratti@redhat.com>
> 
> Can you submit a tdc test case for this bug?

hello Victor,

Thanks for looking at this!

At a first look: TDC is not the correct tool here, because it doesn't
allow changing the qdisc tree while the scapy plugin emits traffic.
Maybe it's better to extend sch_ets.sh from net/forwarding instead?

If so, I can follow-up on net-next with a patch that adds a new
test-case that includes the 3-lines in [1] - while this patch can go
as-is in 'net' (and eventually in stable). In alternative, I can
investigate on TDC adding "sch_plug" to the qdisc tree in a way
that DWRR never deplete, and the crash would then happen with "verifyCmd".


WDYT?

-- 
davide

[1] https://lore.kernel.org/netdev/e08c7f4a6882f260011909a868311c6e9b54f3e4.1639153474.git.dcaratti@redhat.com/