On Tue, 2016-11-22 at 19:06 +0100, Andre Noll wrote:
> On Tue, Nov 22, 09:56, Eric Dumazet wrote
> >
> > >
> > > >
> > > > @@ -157,6 +157,7 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
> > > > memcpy(key_eth_addrs, ð->h_dest, sizeof(*key_eth_addrs));
> > > > }
> > > >
> > > > + barrier();
> > > > again:
> > > > switch (proto) {
> > > > case htons(ETH_P_IP): {
> > >
> > > This patch on top of v4.4.34 makes no difference: I'm still getting
> > > the panic in eth_type_trans().
> > >
> >
> > What compiler are you using exactly ?
>
> gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3, as shipped with
> Ubuntu-12.04. I've also tried gcc (Ubuntu 4.8.4-2ubuntu1~14.04.3)
> 4.8.4 from Ubuntu-14.04. No difference.
>
> >
> > diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
> > index 69e4463a4b1b..48791f372aa2 100644
> > --- a/net/core/flow_dissector.c
> > +++ b/net/core/flow_dissector.c
> > @@ -551,6 +551,7 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
> >
> > key_control->thoff = (u16)nhoff;
> > out:
> > + barrier();
> > key_basic->n_proto = proto;
> > key_basic->ip_proto = ip_proto;
>
> No luck: Still the same panic.
>
> Andre
Okay I think I have figured it out, but I am not sure what a good
solution is.
I think the problem is the fact that the keys may not be initialized
until init_default_flow_dissectors is called and I am not sure that is
happening before the network interface is trying to do DHCP.
I have to look at the initialization framework to verify if that is the
case. It would make sense why I don't usually see it though since I
usually run igb as a module and that doesn't get loaded until later if
I am not mistaken.
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