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[v4,net-next,2/3] ipv6: refactor ip6_finish_output for GSO handling

Message ID 489a6b97c123700de4d28df86a95e79471cfe12b.1698114636.git.yan@cloudflare.com
State New
Headers
Series ipv6: avoid atomic fragment on GSO output |

Commit Message

Yan Zhai Oct. 24, 2023, 2:35 a.m. UTC 
  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 <fw@strlen.de>
Signed-off-by: Yan Zhai <yan@cloudflare.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
---
 net/ipv6/ip6_output.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)
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Patch

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 86efd901ee5a..4010dd97aaf8 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -172,6 +172,16 @@  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;
@@ -185,16 +195,14 @@  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)