On Sun, Feb 15, 2026 at 02:06:42PM +0100, Florian Westphal wrote:
> Jakub Kicinski <kuba@kernel.org> wrote:
> > On Fri, 13 Feb 2026 12:30:58 +0100 Florian Westphal wrote:
> > > > > Looking at the *upper layer*, I don't think it expected drivers to use
> > > > > a single global list for this bit something that is scoped to the
> > > > > net_device.  
> > > > 
> > > > Maybe subjective but the fix seems a little off to me.
> > > > Isn't flow_block_cb_setup_simple() just a "simple" implementation 
> > > > for reuse in drivers locking in there doesn't really guarantee much?  
> > > 
> > > Not sure what you mean.  I see the same pattern as netdevsim in all
> > > drivers using this API. 
> > 
> > Grep for flow_block_cb_add(). Not all drivers use
> 
> static int
> mtk_eth_setup_tc_block(struct net_device *dev, struct flow_block_offload *f)
> {
>         struct mtk_mac *mac = netdev_priv(dev);
>         struct mtk_eth *eth = mac->hw;
>         static LIST_HEAD(block_cb_list);
> 	~~~~~~
> I have a question.
> 
> [..]
>         f->driver_block_list = &block_cb_list;
> 
> Now I have many questions!
> 
> How is this supposed to work?

Last time I met people, I asked how is hw offload actually working
with netns (6 years ago?), someone told me: "maybe there is a driver
that supports it...". I have never seen one, but I am very much
outdates on how this has evolved TBH, I might be wrong.

I don't think any driver really supports netns + hardware offload, so
I suggest to restrict it, see attached patch.

It would be better to add a helper function such as int net_setup_tc()
for the myriad of ->ndo_setup_tc() calls in the code, then move this
check in it to consolidate, but I think you want something you can
pass to -stable at this stage?