net: gro: remove is_ipv6 from napi_gro_cb

Remove is_ipv6 from napi_gro_cb and use sk->sk_family instead.
This frees up space for another ip_fixedid bit that will be added
in the next commit.

udp_sock_create always creates either a AF_INET or a AF_INET6 socket,
so using sk->sk_family is reliable. In IPv6-FOU, cfg->ipv6_v6only is
always enabled.

Signed-off-by: Richard Gobert <richardbgobert@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250923085908.4687-2-richardbgobert@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

2 files changed, 14 insertions, 20 deletions

diff --git a/net/ipv4/fou_core.c b/net/ipv4/fou_core.c
index 3e30745e2c09..3970b6b7ace5 100644
--- a/net/ipv4/fou_core.c
+++ b/net/ipv4/fou_core.c
@@ -228,21 +228,27 @@ drop:
 	return 0;
 }
 
+static const struct net_offload *fou_gro_ops(const struct sock *sk,
+					     int proto)
+{
+	const struct net_offload __rcu **offloads;
+
+	/* FOU doesn't allow IPv4 on IPv6 sockets. */
+	offloads = sk->sk_family == AF_INET6 ? inet6_offloads : inet_offloads;
+	return rcu_dereference(offloads[proto]);
+}
+
 static struct sk_buff *fou_gro_receive(struct sock *sk,
 				       struct list_head *head,
 				       struct sk_buff *skb)
 {
-	const struct net_offload __rcu **offloads;
 	struct fou *fou = fou_from_sock(sk);
 	const struct net_offload *ops;
 	struct sk_buff *pp = NULL;
-	u8 proto;
 
 	if (!fou)
 		goto out;
 
-	proto = fou->protocol;
-
 	/* We can clear the encap_mark for FOU as we are essentially doing
 	 * one of two possible things.  We are either adding an L4 tunnel
 	 * header to the outer L3 tunnel header, or we are simply
@@ -254,8 +260,7 @@ static struct sk_buff *fou_gro_receive(struct sock *sk,
 	/* Flag this frame as already having an outer encap header */
 	NAPI_GRO_CB(skb)->is_fou = 1;
 
-	offloads = NAPI_GRO_CB(skb)->is_ipv6 ? inet6_offloads : inet_offloads;
-	ops = rcu_dereference(offloads[proto]);
+	ops = fou_gro_ops(sk, fou->protocol);
 	if (!ops || !ops->callbacks.gro_receive)
 		goto out;
 
@@ -268,10 +273,8 @@ out:
 static int fou_gro_complete(struct sock *sk, struct sk_buff *skb,
 			    int nhoff)
 {
-	const struct net_offload __rcu **offloads;
 	struct fou *fou = fou_from_sock(sk);
 	const struct net_offload *ops;
-	u8 proto;
 	int err;
 
 	if (!fou) {
@@ -279,10 +282,7 @@ static int fou_gro_complete(struct sock *sk, struct sk_buff *skb,
 		goto out;
 	}
 
-	proto = fou->protocol;
-
-	offloads = NAPI_GRO_CB(skb)->is_ipv6 ? inet6_offloads : inet_offloads;
-	ops = rcu_dereference(offloads[proto]);
+	ops = fou_gro_ops(sk, fou->protocol);
 	if (WARN_ON(!ops || !ops->callbacks.gro_complete)) {
 		err = -ENOSYS;
 		goto out;
@@ -323,7 +323,6 @@ static struct sk_buff *gue_gro_receive(struct sock *sk,
 				       struct list_head *head,
 				       struct sk_buff *skb)
 {
-	const struct net_offload __rcu **offloads;
 	const struct net_offload *ops;
 	struct sk_buff *pp = NULL;
 	struct sk_buff *p;
@@ -450,8 +449,7 @@ next_proto:
 	/* Flag this frame as already having an outer encap header */
 	NAPI_GRO_CB(skb)->is_fou = 1;
 
-	offloads = NAPI_GRO_CB(skb)->is_ipv6 ? inet6_offloads : inet_offloads;
-	ops = rcu_dereference(offloads[proto]);
+	ops = fou_gro_ops(sk, proto);
 	if (!ops || !ops->callbacks.gro_receive)
 		goto out;
 
@@ -467,7 +465,6 @@ out:
 static int gue_gro_complete(struct sock *sk, struct sk_buff *skb, int nhoff)
 {
 	struct guehdr *guehdr = (struct guehdr *)(skb->data + nhoff);
-	const struct net_offload __rcu **offloads;
 	const struct net_offload *ops;
 	unsigned int guehlen = 0;
 	u8 proto;
@@ -494,8 +491,7 @@ static int gue_gro_complete(struct sock *sk, struct sk_buff *skb, int nhoff)
 		return err;
 	}
 
-	offloads = NAPI_GRO_CB(skb)->is_ipv6 ? inet6_offloads : inet_offloads;
-	ops = rcu_dereference(offloads[proto]);
+	ops = fou_gro_ops(sk, proto);
 	if (WARN_ON(!ops || !ops->callbacks.gro_complete))
 		goto out;
 
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index b1f3fd302e9d..19d0b5b09ffa 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -891,8 +891,6 @@ struct sk_buff *udp4_gro_receive(struct list_head *head, struct sk_buff *skb)
 		skb_gro_checksum_try_convert(skb, IPPROTO_UDP,
 					     inet_gro_compute_pseudo);
 skip:
-	NAPI_GRO_CB(skb)->is_ipv6 = 0;
-
 	if (static_branch_unlikely(&udp_encap_needed_key))
 		sk = udp4_gro_lookup_skb(skb, uh->source, uh->dest);