Re: [PATCH net] net: stmmac: allow a tc-taprio base-time of zero

[Yannick Vignon]

Hi Kurt,

On 11/9/2021 3:47 PM, Kurt Kanzenbach wrote:
> On Tue Nov 09 2021, Vladimir Oltean wrote:
> > On Tue, Nov 09, 2021 at 09:20:53AM +0100, Kurt Kanzenbach wrote:
> > > Hi Vladimir,
> > >
> > > On Mon Nov 08 2021, Vladimir Oltean wrote:
> > > > Commit fe28c53ed71d ("net: stmmac: fix taprio configuration when
> > > > base_time is in the past") allowed some base time values in the past,
> > > > but apparently not all, the base-time value of 0 (Jan 1st 1970) is still
> > > > explicitly denied by the driver.
> > > >
> > > > Remove the bogus check.
> > > >
> > > > Fixes: b60189e0392f ("net: stmmac: Integrate EST with TAPRIO scheduler API")
> > > > Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
> > >
> > > I've experienced the same problem and wanted to send a patch for
> > > it. Thanks!
> > >
> > > Reviewed-by: Kurt Kanzenbach <kurt@xxxxxxxxxxxxx>
> >
> > Cool. So you had that patch queued up? What other stmmac patches do you
> > have queued up? :).
>
> I'm experiencing some problems with XDP using this driver. We're
> currently investigating.

Could you elaborate a bit?
I've been using XDP a lot with the stmmac driver recently, and while I 
did see issues initially, most of them got fixed by using a recent 
enough kernel, thanks to the following commits:
. a6451192da2691dcf39507bd ("net: stmmac: fix kernel panic due to NULL 
pointer dereference of xsk_pool")
. 2b9fff64f03219d78044d1ab ("net: stmmac: fix kernel panic due to NULL 
pointer dereference of buf->xdp")
. 81d0885d68ec427e62044cf4 ("net: stmmac: Fix overall budget calculation 
for rxtx_napi")

There was one remaining issue for which I need to push a fix: if you 
remove an XDP program from an interface while transmitting traffic, you 
are likely to trigger a kernel panic. I'll try to push a patch for that 
soon.

> Thanks,
> Kurt

Regards,
Yannick