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Date: Tue, 21 May 2019 12:47:23 +0800 From: Jason Wang <jasowang@...hat.com> To: Jiri Pirko <jiri@...nulli.us>, Stephen Hemminger <stephen@...workplumber.org> Cc: netdev@...r.kernel.org, davem@...emloft.net, xdp-newbies@...r.kernel.org, bpf@...r.kernel.org, Stephen Hemminger <sthemmin@...rosoft.com> Subject: Re: [PATCH v2 net 2/2] net: core: generic XDP support for stacked device On 2019/5/20 下午5:11, Jiri Pirko wrote: > Sun, May 19, 2019 at 05:10:46AM CEST, stephen@...workplumber.org 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@...hat.com> >> Fixes: d445516966dc ("net: xdp: support xdp generic on virtual devices") >> Signed-off-by: Stephen Hemminger <sthemmin@...rosoft.com> >> Acked-by: Jason Wang <jasowang@...hat.com> >> --- >> 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? > > 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? > 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. Thanks > > > >> goto another_round; >> case RX_HANDLER_EXACT: >> deliver_exact = true; >> -- >> 2.20.1 >>
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