Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) client-ip=2620:137:e000::3:7;
Date:   Thu, 19 Oct 2023 22:32:49 -0700
From:   Yan Zhai <yan@cloudflare.com>
To:     netdev@vger.kernel.org
Cc:     "David S. Miller" <davem@davemloft.net>,
        David Ahern <dsahern@kernel.org>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, Aya Levin <ayal@nvidia.com>,
        Tariq Toukan <tariqt@nvidia.com>, linux-kernel@vger.kernel.org,
        kernel-team@cloudflare.com, Florian Westphal <fw@strlen.de>,
        Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
        Alexander H Duyck <alexander.duyck@gmail.com>
Subject: [PATCH v3 net-next 2/3] ipv6: refactor ip6_finish_output for GSO
 handling
Message-ID: <496ccff707e16e98163d2a3fbcfbc1f824fd8ec3.1697779681.git.yan@cloudflare.com>
References: <cover.1697779681.git.yan@cloudflare.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <cover.1697779681.git.yan@cloudflare.com>
Precedence: bulk

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>
---
 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