Subject: Re: [PATCH net-next] net: shaper: Reject zero weight in shaper config

From: Jakub Kicinski <[email-masked]>
Date: Mon, 13 Apr 2026 14:50:39 -0700

On Fri, 10 Apr 2026 15:51:23 -0700 Mohsin Bashir wrote:
> A zero weight is meaningless for DWRR scheduling and can cause
> starvation of the affected node. Add a min-value constraint to
> the weight attribute in the net_shaper netlink spec so that zero
> is rejected at the netlink policy level.
> 
> Found while prototyping a new driver, existing drivers are not
> affected.

AI review points out that if the netlink attr is not present core will
leave the DWRR weight as 0 in the struct. I guess we need to think this
thru a little more carefully. What should the "default" weight be?
What if user specifies weights only for subset of leaves?

This part of the uAPI seems under-defined.

Maybe a better adjustment would be to make core set the weight to 1
automatically if the user has not defined it? Only when sending it to
the driver tho, because we'd still want it to not be reported back to
user space. Not sure how hairy it'd get code-wise.