2023-10-20 05:33:05

by Yan Zhai

Subject: [PATCH v3 net-next 2/3] ipv6: refactor ip6_finish_output for GSO handling

Separate GSO and non-GSO packets handling to make the logic cleaner. For
GSO packets, frag_max_size check can be omitted because it is only
useful for packets defragmented by netfilter hooks. Both local output
and GRO logic won't produce GSO packets when defragment is needed. This
also mirrors what IPv4 side code is doing.

Suggested-by: Florian Westphal <[email protected]>
Signed-off-by: Yan Zhai <[email protected]>
---
net/ipv6/ip6_output.c | 22 +++++++++++++++-------
1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index ae87a3817d4a..3270d56b5c37 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -170,6 +170,16 @@ ip6_finish_output_gso_slowpath_drop(struct net *net, struct sock *sk,
return ret;
}

+static int ip6_finish_output_gso(struct net *net, struct sock *sk,
+ struct sk_buff *skb, unsigned int mtu)
+{
+ if (!(IP6CB(skb)->flags & IP6SKB_FAKEJUMBO) &&
+ !skb_gso_validate_network_len(skb, mtu))
+ return ip6_finish_output_gso_slowpath_drop(net, sk, skb, mtu);
+
+ return ip6_finish_output2(net, sk, skb);
+}
+
static int __ip6_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
{
unsigned int mtu;
@@ -183,16 +193,14 @@ static int __ip6_finish_output(struct net *net, struct sock *sk, struct sk_buff
#endif

mtu = ip6_skb_dst_mtu(skb);
- if (skb_is_gso(skb) &&
- !(IP6CB(skb)->flags & IP6SKB_FAKEJUMBO) &&
- !skb_gso_validate_network_len(skb, mtu))
- return ip6_finish_output_gso_slowpath_drop(net, sk, skb, mtu);
+ if (skb_is_gso(skb))
+ return ip6_finish_output_gso(net, sk, skb, mtu);

- if ((skb->len > mtu && !skb_is_gso(skb)) ||
+ if (skb->len > mtu ||
(IP6CB(skb)->frag_max_size && skb->len > IP6CB(skb)->frag_max_size))
return ip6_fragment(net, sk, skb, ip6_finish_output2);
- else
- return ip6_finish_output2(net, sk, skb);
+
+ return ip6_finish_output2(net, sk, skb);
}

static int ip6_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
--
2.30.2

2023-10-20 19:16:29

by Willem de Bruijn

Subject: Re: [PATCH v3 net-next 2/3] ipv6: refactor ip6_finish_output for GSO handling

Yan Zhai wrote:
> Separate GSO and non-GSO packets handling to make the logic cleaner. For
> GSO packets, frag_max_size check can be omitted because it is only
> useful for packets defragmented by netfilter hooks. Both local output
> and GRO logic won't produce GSO packets when defragment is needed. This
> also mirrors what IPv4 side code is doing.
>
> Suggested-by: Florian Westphal <[email protected]>
> Signed-off-by: Yan Zhai <[email protected]>

Reviewed-by: Willem de Bruijn <[email protected]>

Thanks for splitting up the series. This change alone is subtle enough
that it benefits from standing alone. I thought it was intended to be
a NOOP, but you indeed call out the frag_max_size special case.