From: Jiri Pirko <jiri@resnulli.us>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: netdev@vger.kernel.org, davem@davemloft.net,
xdp-newbies@vger.kernel.org, bpf@vger.kernel.org,
Stephen Hemminger <sthemmin@microsoft.com>,
Jason Wang <jasowang@redhat.com>
Subject: Re: [PATCH v2 net 2/2] net: core: generic XDP support for stacked device
Date: Mon, 20 May 2019 11:11:05 +0200 [thread overview]
Message-ID: <20190520091105.GA2142@nanopsycho> (raw)
In-Reply-To: <20190519031046.4049-3-sthemmin@microsoft.com>
Sun, May 19, 2019 at 05:10:46AM CEST, stephen@networkplumber.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@redhat.com>
>Fixes: d445516966dc ("net: xdp: support xdp generic on virtual devices")
>Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
>Acked-by: Jason Wang <jasowang@redhat.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).
The reason for troubles was often fact that different flows were treated
differently (vlan accel/non-accel).
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()?
> goto another_round;
> case RX_HANDLER_EXACT:
> deliver_exact = true;
>--
>2.20.1
>
next prev parent reply other threads:[~2019-05-20 9:11 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-19 3:10 [PATCH v2 net 0/2] XDP generic related fixes Stephen Hemminger
2019-05-19 3:10 ` [PATCH v2 net 1/2] netvsc: unshare skb in VF rx handler Stephen Hemminger
2019-05-19 3:10 ` [PATCH v2 net 2/2] net: core: generic XDP support for stacked device Stephen Hemminger
2019-05-20 9:11 ` Jiri Pirko [this message]
2019-05-20 15:53 ` Stephen Hemminger
2019-05-21 5:54 ` Jason Wang
2019-05-20 16:04 ` Stephen Hemminger
2019-05-21 6:15 ` Jiri Pirko
2019-05-21 14:45 ` Stephen Hemminger
2019-05-21 15:21 ` Jiri Pirko
2019-05-21 4:47 ` Jason Wang
2019-05-21 6:08 ` Jiri Pirko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190520091105.GA2142@nanopsycho \
--to=jiri@resnulli.us \
--cc=bpf@vger.kernel.org \
--cc=davem@davemloft.net \
--cc=jasowang@redhat.com \
--cc=netdev@vger.kernel.org \
--cc=stephen@networkplumber.org \
--cc=sthemmin@microsoft.com \
--cc=xdp-newbies@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).