From: Jakub Kicinski <kuba@kernel.org>
To: Alexander Lobakin <alobakin@pm.me>
Cc: "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Miaohe Lin <linmiaohe@huawei.com>,
Martin Varghese <martin.varghese@nokia.com>,
Pravin B Shelar <pshelar@ovn.org>,
Willem de Bruijn <willemb@google.com>,
Guillaume Nault <gnault@redhat.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Florian Westphal <fw@strlen.de>,
Steffen Klassert <steffen.klassert@secunet.com>,
Paolo Abeni <pabeni@redhat.com>,
Yadu Kishore <kyk.segfault@gmail.com>,
Vladimir Oltean <vladimir.oltean@nxp.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next] net: skb_vlan_untag(): don't reset transport offset if set by GRO layer
Date: Mon, 9 Nov 2020 15:29:13 -0800 [thread overview]
Message-ID: <20201109152913.289c3cac@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> (raw)
In-Reply-To: <zYurwsZRN7BkqSoikWQLVqHyxz18h4LhHU4NFa2Vw@cp4-web-038.plabs.ch>
On Thu, 05 Nov 2020 21:29:01 +0000 Alexander Lobakin wrote:
> Similar to commit fda55eca5a33f
> ("net: introduce skb_transport_header_was_set()"), avoid resetting
> transport offsets that were already set by GRO layer. This not only
> mirrors the behavior of __netif_receive_skb_core(), but also makes
> sense when it comes to UDP GSO fraglists forwarding: transport offset
> of such skbs is set only once by GRO receive callback and remains
> untouched and correct up to the xmitting driver in 1:1 case, but
> becomes junk after untagging in ingress VLAN case and breaks UDP
> GSO offload. This does not happen after this change, and all types
> of forwarding of UDP GSO fraglists work as expected.
>
> Signed-off-by: Alexander Lobakin <alobakin@pm.me>
> ---
> net/core/skbuff.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index c5e6c0b83a92..39c13b9cf79d 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -5441,9 +5441,11 @@ struct sk_buff *skb_vlan_untag(struct sk_buff *skb)
> goto err_free;
>
> skb_reset_network_header(skb);
> - skb_reset_transport_header(skb);
> skb_reset_mac_len(skb);
>
> + if (!skb_transport_header_was_set(skb))
> + skb_reset_transport_header(skb);
> +
Patch looks fine, thanks, but I don't understand why you decided to
move the reset? It's not like it's not in order of headers, either.
Let's keep the series of resets identical to __netif_receive_skb_core(),
shall we?
> return skb;
>
> err_free:
next prev parent reply other threads:[~2020-11-09 23:29 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-05 21:29 [PATCH net-next] net: skb_vlan_untag(): don't reset transport offset if set by GRO layer Alexander Lobakin
2020-11-09 23:29 ` Jakub Kicinski [this message]
2020-11-09 23:38 ` Alexander Lobakin
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