netdev - Re: [PATCH net] net: sched: cls: Fix offloading when ingress dev is vxlan

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Date:   Tue, 5 Jun 2018 11:59:46 -0700
From:   Jakub Kicinski <kubakici@...pl>
To:     Paul Blakey <paulb@...lanox.com>
Cc:     Jiri Pirko <jiri@...lanox.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
        Yevgeny Kliteynik <kliteyn@...lanox.com>,
        Roi Dayan <roid@...lanox.com>,
        Shahar Klein <shahark@...lanox.com>,
        Mark Bloch <markb@...lanox.com>,
        Or Gerlitz <ogerlitz@...lanox.com>
Subject: Re: [PATCH net] net: sched: cls: Fix offloading when ingress dev is
 vxlan

On Tue, 5 Jun 2018 11:57:47 -0700, Jakub Kicinski wrote:
> On Tue,  5 Jun 2018 11:04:03 +0300, Paul Blakey wrote:
> > When using a vxlan device as the ingress dev, we count it as a
> > "no offload dev", so when such a rule comes and err stop is true,
> > we fail early and don't try the egdev route which can offload it
> > through the egress device.
> > 
> > Fix that by not calling the block offload if one of the devices
> > attached to it is not offload capable, but make sure egress on such case
> > is capable instead.
> > 
> > Fixes: caa7260156eb ("net: sched: keep track of offloaded filters [..]")
> > Reviewed-by: Roi Dayan <roid@...lanox.com>
> > Acked-by: Jiri Pirko <jiri@...lanox.com>
> > Signed-off-by: Paul Blakey <paulb@...lanox.com>  
> 
> Very poor commit message.  What you're doing is re-enabling skip_sw
> filters on tunnel devices which semantically make no sense and
> shouldn't have been allowed in the first place.
> 
> This will breaks block sharing between tunnels and HW netdevs (because
> you skip the tcf_block_cb_call() completely).  The entire egdev idea
> remains badly broken accepting filters like this:
> 
> # tc filter add dev vxlan0 ingress \
> 	matchall action skip_sw \
> 		mirred egress redirect dev lo \
> 		mirred egress redirect dev sw1np0

For above we probably need something like this (untested):

diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 3f4cf930f809..71e5eebec31a 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -1511,7 +1511,7 @@ int tc_setup_cb_egdev_call(const struct net_device *dev,
        struct tcf_action_egdev *egdev = tcf_action_egdev_lookup(dev);
 
        if (!egdev)
-               return 0;
+               return err_stop ? -EOPNOTSUPP : 0;
        return tcf_action_egdev_cb_call(egdev, type, type_data, err_stop);
 }
 EXPORT_SYMBOL_GPL(tc_setup_cb_egdev_call);

But the correct fix is to remove egdev crutch completely IMO.