netdev - [PATCH net-next] udp: udplite is unlikely

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Message-ID: <20260105101719.2378881-1-edumazet@google.com>
Date: Mon,  5 Jan 2026 10:17:19 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: Willem de Bruijn <willemb@...gle.com>, Simon Horman <horms@...nel.org>, netdev@...r.kernel.org, 
	eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next] udp: udplite is unlikely

Add some unlikely() annotations to speed up the fast path,
at least with clang compiler.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 include/linux/udp.h | 2 +-
 include/net/udp.h   | 8 ++++----
 net/ipv4/udp.c      | 5 +++--
 net/ipv6/udp.c      | 5 +++--
 4 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/include/linux/udp.h b/include/linux/udp.h
index 58795688a186..1cbf6b4d3aab 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -236,7 +236,7 @@ static inline void udp_allow_gso(struct sock *sk)
 	hlist_nulls_for_each_entry_rcu(__up, node, list, udp_lrpa_node)
 #endif
 
-#define IS_UDPLITE(__sk) (__sk->sk_protocol == IPPROTO_UDPLITE)
+#define IS_UDPLITE(__sk) (unlikely(__sk->sk_protocol == IPPROTO_UDPLITE))
 
 static inline struct sock *udp_tunnel_sk(const struct net *net, bool is_ipv6)
 {
diff --git a/include/net/udp.h b/include/net/udp.h
index a061d1b22ddc..700dbedcb15f 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -527,18 +527,18 @@ static inline int copy_linear_skb(struct sk_buff *skb, int len, int off,
  * 	SNMP statistics for UDP and UDP-Lite
  */
 #define UDP_INC_STATS(net, field, is_udplite)		      do { \
-	if (is_udplite) SNMP_INC_STATS((net)->mib.udplite_statistics, field);       \
+	if (unlikely(is_udplite)) SNMP_INC_STATS((net)->mib.udplite_statistics, field);	\
 	else		SNMP_INC_STATS((net)->mib.udp_statistics, field);  }  while(0)
 #define __UDP_INC_STATS(net, field, is_udplite) 	      do { \
-	if (is_udplite) __SNMP_INC_STATS((net)->mib.udplite_statistics, field);         \
+	if (unlikely(is_udplite)) __SNMP_INC_STATS((net)->mib.udplite_statistics, field);	\
 	else		__SNMP_INC_STATS((net)->mib.udp_statistics, field);    }  while(0)
 
 #define __UDP6_INC_STATS(net, field, is_udplite)	    do { \
-	if (is_udplite) __SNMP_INC_STATS((net)->mib.udplite_stats_in6, field);\
+	if (unlikely(is_udplite)) __SNMP_INC_STATS((net)->mib.udplite_stats_in6, field);	\
 	else		__SNMP_INC_STATS((net)->mib.udp_stats_in6, field);  \
 } while(0)
 #define UDP6_INC_STATS(net, field, __lite)		    do { \
-	if (__lite) SNMP_INC_STATS((net)->mib.udplite_stats_in6, field);  \
+	if (unlikely(__lite)) SNMP_INC_STATS((net)->mib.udplite_stats_in6, field);	\
 	else	    SNMP_INC_STATS((net)->mib.udp_stats_in6, field);      \
 } while(0)
 
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index ffe074cb5865..a5b9de2bd1a3 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1193,7 +1193,7 @@ static int udp_send_skb(struct sk_buff *skb, struct flowi4 *fl4,
 
 send:
 	err = ip_send_skb(sock_net(sk), skb);
-	if (err) {
+	if (unlikely(err)) {
 		if (err == -ENOBUFS &&
 		    !inet_test_bit(RECVERR, sk)) {
 			UDP_INC_STATS(sock_net(sk),
@@ -2428,7 +2428,8 @@ static int udp_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb)
 	/*
 	 * 	UDP-Lite specific tests, ignored on UDP sockets
 	 */
-	if (udp_test_bit(UDPLITE_RECV_CC, sk) && UDP_SKB_CB(skb)->partial_cov) {
+	if (unlikely(udp_test_bit(UDPLITE_RECV_CC, sk) &&
+		     UDP_SKB_CB(skb)->partial_cov)) {
 		u16 pcrlen = READ_ONCE(up->pcrlen);
 
 		/*
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 794c13674e8a..010b909275dd 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -875,7 +875,8 @@ static int udpv6_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb)
 	/*
 	 * UDP-Lite specific tests, ignored on UDP sockets (see net/ipv4/udp.c).
 	 */
-	if (udp_test_bit(UDPLITE_RECV_CC, sk) && UDP_SKB_CB(skb)->partial_cov) {
+	if (unlikely(udp_test_bit(UDPLITE_RECV_CC, sk) &&
+		     UDP_SKB_CB(skb)->partial_cov)) {
 		u16 pcrlen = READ_ONCE(up->pcrlen);
 
 		if (pcrlen == 0) {          /* full coverage was set  */
@@ -1439,7 +1440,7 @@ static int udp_v6_send_skb(struct sk_buff *skb, struct flowi6 *fl6,
 
 send:
 	err = ip6_send_skb(skb);
-	if (err) {
+	if (unlikely(err)) {
 		if (err == -ENOBUFS && !inet6_test_bit(RECVERR6, sk)) {
 			UDP6_INC_STATS(sock_net(sk),
 				       UDP_MIB_SNDBUFERRORS, is_udplite);
-- 
2.52.0.351.gbe84eed79e-goog