Tue, May 21, 2019 at 06:47:23AM CEST, jasowang@xxxxxxxxxx wrote:
>
>On 2019/5/20 下午5:11, Jiri Pirko wrote:
>> Sun, May 19, 2019 at 05:10:46AM CEST, stephen@xxxxxxxxxxxxxxxxxx wrote:
>> > When a device is stacked like (team, bonding, failsafe or netvsc) the
>> > XDP generic program for the parent device is not called. In these
>> > cases, the rx handler changes skb->dev to its own in the receive
>> > handler, and returns RX_HANDLER_ANOTHER. Fix this by calling
>> > do_xdp_generic if necessary before starting another round.
>> >
>> > Review of all the places RX_HANDLER_ANOTHER is returned
>> > show that the current devices do correctly change skb->dev.
>> >
>> > There was an older patch that got abandoned that did the
>> > same thing, this is just a rewrite.
>> >
>> > Suggested-by: Jason Wang <jasowang@xxxxxxxxxx>
>> > Fixes: d445516966dc ("net: xdp: support xdp generic on virtual devices")
>> > Signed-off-by: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
>> > Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
>> > ---
>> > net/core/dev.c | 10 ++++++++++
>> > 1 file changed, 10 insertions(+)
>> >
>> > diff --git a/net/core/dev.c b/net/core/dev.c
>> > index b6b8505cfb3e..240d0b2de1a8 100644
>> > --- a/net/core/dev.c
>> > +++ b/net/core/dev.c
>> > @@ -4921,6 +4921,16 @@ static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc,
>> > ret = NET_RX_SUCCESS;
>> > goto out;
>> > case RX_HANDLER_ANOTHER:
>> > + if (static_branch_unlikely(&generic_xdp_needed_key)) {
>> > + struct bpf_prog *xdp_prog;
>> > +
>> > + xdp_prog = rcu_dereference(skb->dev->xdp_prog);
>> > + ret = do_xdp_generic(xdp_prog, skb);
>> > + if (ret != XDP_PASS) {
>> > + ret = NET_RX_SUCCESS;
>> > + goto out;
>> > + }
>> > + }
>> I'm always scarred of changes like this. The history tells us that this
>> codepaths are very fragile. It took us non-trivial efford to fix bonding
>> here, not to mention vlans (that was pain).
>
>
>I may miss something, did you see any issue for bonding with this patch?
No, I was talking about past.
>
>
>>
>> The reason for troubles was often fact that different flows were treated
>> differently (vlan accel/non-accel).
>
>
>Do you mean we need do something similar after vlan_do_receive() returns
>true?
No.
>
>
>> This patch calls do_xdp_generic for master device in different point in
>> the receive patch comparing to lower device. Would it be possible to
>> unify this? E.g. by moving do_xdp_generice() call from
>> netif_rx_internal()/netif_receive_skb_internal() here,
>> to the beginning of __netif_receive_skb_core()?
>
>
>Probably just after another_round label. And this means generic XDP is done
>after RPS which could be even better.
Yes. That is exactly the place I have in mind.
>
>Thanks
>
>
>>
>>
>>
>> > goto another_round;
>> > case RX_HANDLER_EXACT:
>> > deliver_exact = true;
>> > --
>> > 2.20.1
>> >
