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Message-ID: <20250912112420.4394-3-mmietus97@yahoo.com>
Date: Fri, 12 Sep 2025 13:24:19 +0200
From: Marek Mietus <mmietus97@...oo.com>
To: netdev@...r.kernel.org,
antonio@...nvpn.net,
kuba@...nel.org
Cc: openvpn-devel@...ts.sourceforge.net,
Marek Mietus <mmietus97@...oo.com>
Subject: [PATCH net-next v2 2/3] net: tunnel: implement noref flows in udp_tunnel_xmit_skb
In cases where udp_tunnel_xmit_skb is called inside a RCU read-side
critical section, we can avoid referencing the dst_entry.
Implement noref variants for udp_tunnel_xmit_skb and iptunnel_xmit to be
used in noref flows.
Signed-off-by: Marek Mietus <mmietus97@...oo.com>
---
include/net/ip_tunnels.h | 3 +++
include/net/udp_tunnel.h | 4 ++++
net/ipv4/ip_tunnel_core.c | 34 +++++++++++++++++++++++++++-------
net/ipv4/udp_tunnel_core.c | 29 +++++++++++++++++++++++++----
4 files changed, 59 insertions(+), 11 deletions(-)
diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h
index 8cf1380f3656..6dcea237bf21 100644
--- a/include/net/ip_tunnels.h
+++ b/include/net/ip_tunnels.h
@@ -604,6 +604,9 @@ static inline int iptunnel_pull_header(struct sk_buff *skb, int hdr_len,
void iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
__be32 src, __be32 dst, u8 proto,
u8 tos, u8 ttl, __be16 df, bool xnet, u16 ipcb_flags);
+void iptunnel_xmit_noref(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
+ __be32 src, __be32 dst, u8 proto,
+ u8 tos, u8 ttl, __be16 df, bool xnet, u16 ipcb_flags);
struct metadata_dst *iptunnel_metadata_reply(struct metadata_dst *md,
gfp_t flags);
int skb_tunnel_check_pmtu(struct sk_buff *skb, struct dst_entry *encap_dst,
diff --git a/include/net/udp_tunnel.h b/include/net/udp_tunnel.h
index 9acef2fbd2fd..033098ebf789 100644
--- a/include/net/udp_tunnel.h
+++ b/include/net/udp_tunnel.h
@@ -135,6 +135,10 @@ void udp_tunnel_xmit_skb(struct rtable *rt, struct sock *sk, struct sk_buff *skb
__be32 src, __be32 dst, __u8 tos, __u8 ttl,
__be16 df, __be16 src_port, __be16 dst_port,
bool xnet, bool nocheck, u16 ipcb_flags);
+void udp_tunnel_xmit_skb_noref(struct rtable *rt, struct sock *sk, struct sk_buff *skb,
+ __be32 src, __be32 dst, __u8 tos, __u8 ttl,
+ __be16 df, __be16 src_port, __be16 dst_port,
+ bool xnet, bool nocheck, u16 ipcb_flags);
void udp_tunnel6_xmit_skb(struct dst_entry *dst, struct sock *sk,
struct sk_buff *skb,
diff --git a/net/ipv4/ip_tunnel_core.c b/net/ipv4/ip_tunnel_core.c
index cc9915543637..8b03fb380397 100644
--- a/net/ipv4/ip_tunnel_core.c
+++ b/net/ipv4/ip_tunnel_core.c
@@ -47,10 +47,10 @@ const struct ip6_tnl_encap_ops __rcu *
ip6tun_encaps[MAX_IPTUN_ENCAP_OPS] __read_mostly;
EXPORT_SYMBOL(ip6tun_encaps);
-void iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
- __be32 src, __be32 dst, __u8 proto,
- __u8 tos, __u8 ttl, __be16 df, bool xnet,
- u16 ipcb_flags)
+static void __iptunnel_xmit(struct sock *sk, struct rtable *rt,
+ struct sk_buff *skb, __be32 src, __be32 dst,
+ __u8 proto, __u8 tos, __u8 ttl, __be16 df,
+ u16 ipcb_flags)
{
int pkt_len = skb->len - skb_inner_network_offset(skb);
struct net *net = dev_net(rt->dst.dev);
@@ -58,10 +58,7 @@ void iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
struct iphdr *iph;
int err;
- skb_scrub_packet(skb, xnet);
-
skb_clear_hash_if_not_l4(skb);
- skb_dst_set(skb, &rt->dst);
memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
IPCB(skb)->flags = ipcb_flags;
@@ -89,8 +86,31 @@ void iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
iptunnel_xmit_stats(dev, pkt_len);
}
}
+
+void iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
+ __be32 src, __be32 dst, __u8 proto,
+ __u8 tos, __u8 ttl, __be16 df, bool xnet,
+ u16 ipcb_flags)
+{
+ skb_scrub_packet(skb, xnet);
+ skb_dst_set(skb, &rt->dst);
+
+ __iptunnel_xmit(sk, rt, skb, src, dst, proto, tos, ttl, df, ipcb_flags);
+}
EXPORT_SYMBOL_GPL(iptunnel_xmit);
+void iptunnel_xmit_noref(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
+ __be32 src, __be32 dst, __u8 proto,
+ __u8 tos, __u8 ttl, __be16 df, bool xnet,
+ u16 ipcb_flags)
+{
+ skb_scrub_packet(skb, xnet);
+ skb_dst_set_noref(skb, &rt->dst);
+
+ __iptunnel_xmit(sk, rt, skb, src, dst, proto, tos, ttl, df, ipcb_flags);
+}
+EXPORT_SYMBOL_GPL(iptunnel_xmit_noref);
+
int __iptunnel_pull_header(struct sk_buff *skb, int hdr_len,
__be16 inner_proto, bool raw_proto, bool xnet)
{
diff --git a/net/ipv4/udp_tunnel_core.c b/net/ipv4/udp_tunnel_core.c
index fce945f23069..c0e9007cf081 100644
--- a/net/ipv4/udp_tunnel_core.c
+++ b/net/ipv4/udp_tunnel_core.c
@@ -170,10 +170,9 @@ void udp_tunnel_notify_del_rx_port(struct socket *sock, unsigned short type)
}
EXPORT_SYMBOL_GPL(udp_tunnel_notify_del_rx_port);
-void udp_tunnel_xmit_skb(struct rtable *rt, struct sock *sk, struct sk_buff *skb,
- __be32 src, __be32 dst, __u8 tos, __u8 ttl,
- __be16 df, __be16 src_port, __be16 dst_port,
- bool xnet, bool nocheck, u16 ipcb_flags)
+static void udp_tunnel_add_hdr(struct sk_buff *skb, __be32 src,
+ __be32 dst, __be16 src_port,
+ __be16 dst_port, bool nocheck)
{
struct udphdr *uh;
@@ -188,12 +187,34 @@ void udp_tunnel_xmit_skb(struct rtable *rt, struct sock *sk, struct sk_buff *skb
memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
udp_set_csum(nocheck, skb, src, dst, skb->len);
+}
+
+void udp_tunnel_xmit_skb(struct rtable *rt, struct sock *sk,
+ struct sk_buff *skb, __be32 src, __be32 dst,
+ __u8 tos, __u8 ttl, __be16 df, __be16 src_port,
+ __be16 dst_port, bool xnet, bool nocheck,
+ u16 ipcb_flags)
+{
+ udp_tunnel_add_hdr(skb, src, dst, src_port, dst_port, nocheck);
iptunnel_xmit(sk, rt, skb, src, dst, IPPROTO_UDP, tos, ttl, df, xnet,
ipcb_flags);
}
EXPORT_SYMBOL_GPL(udp_tunnel_xmit_skb);
+void udp_tunnel_xmit_skb_noref(struct rtable *rt, struct sock *sk,
+ struct sk_buff *skb, __be32 src, __be32 dst,
+ __u8 tos, __u8 ttl, __be16 df, __be16 src_port,
+ __be16 dst_port, bool xnet, bool nocheck,
+ u16 ipcb_flags)
+{
+ udp_tunnel_add_hdr(skb, src, dst, src_port, dst_port, nocheck);
+
+ iptunnel_xmit_noref(sk, rt, skb, src, dst, IPPROTO_UDP, tos, ttl, df,
+ xnet, ipcb_flags);
+}
+EXPORT_SYMBOL_GPL(udp_tunnel_xmit_skb_noref);
+
void udp_tunnel_sock_release(struct socket *sock)
{
rcu_assign_sk_user_data(sock->sk, NULL);
--
2.51.0
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