Re: [net-next PATCH v13 2/9] net: dsa: realtek: rtl8365mb: reject unsupported topologies

[Andrew Lunn]

On Sun, Jun 07, 2026 at 02:55:07PM +0200, Mieczyslaw Nalewaj wrote:
> On 6/6/2026 10:29 AM, Luiz Angelo Daros de Luca wrote:
> > Explicitly enforce the presence of a CPU port (-EINVAL) and reject DSA
> > cascade links (-EOPNOTSUPP) during setup to prevent silent failures.
> > 
> > These topologies were already non-functional. Without a CPU port, the
> > driver does not activate CPU tagging. Additionally, the switch hardware
> > was not designed to be cascaded, and DSA links never worked because
> > CPU tagging is not enabled for them.
> > 
> > Reviewed-by: Mieczyslaw Nalewaj <namiltd@xxxxxxxxx>
> > Reviewed-by: Linus Walleij <linusw@xxxxxxxxxx>
> > Signed-off-by: Luiz Angelo Daros de Luca <luizluca@xxxxxxxxx>
> > ---
> [...]
> >drivers/net/dsa/realtek/rtl8365mb.c:rtl8365mb_get_stats64() {
> >    ...
> >	mb = priv->chip_data;
> >	p = &mb->ports[port];
> >	spin_lock(&p->stats_lock);
> >	memcpy(s, &p->stats, sizeof(*s));
> >	spin_unlock(&p->stats_lock);
> >}
> 
> Sashiko reports a potential deadlock around stats_lock, however I couldn't find a call chain reaching rtl8365mb_get_stats64() from softirq context. Can anyone point to such a path?

Enable CONFIG_PROVE_LOCKING and use the device, get the statistics
etc. If you hit the two paths with a potential deadlock you will get a
report.

	Andrew