linux-kernel - [PATCH net-next v2 5/7] netpoll: factor out UDP header setup into push

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Message-Id: <20250702-netpoll_untagle_ip-v2-5-13cf3db24e2b@debian.org>
Date: Wed, 02 Jul 2025 03:06:37 -0700
From: Breno Leitao <leitao@...ian.org>
To: "David S. Miller" <davem@...emloft.net>, 
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
 Andrew Lunn <andrew+netdev@...n.ch>, Shuah Khan <shuah@...nel.org>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-kselftest@...r.kernel.org, Breno Leitao <leitao@...ian.org>, 
 kernel-team@...a.com
Subject: [PATCH net-next v2 5/7] netpoll: factor out UDP header setup into
 push_udp() helper

Move UDP header construction from netpoll_send_udp() into a new
static helper function push_udp(). This completes the protocol
layer refactoring by:

1. Creating a dedicated helper for UDP header assembly
2. Removing UDP-specific logic from the main send function
3. Establishing a consistent pattern with existing IPv4/IPv6 helpers:
   - push_udp()
   - push_ipv4()
   - push_ipv6()

The change improves code organization and maintains the encapsulation
pattern established in previous refactorings.

Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 net/core/netpoll.c | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index ff64e94df5351..70035e27d91cc 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -473,11 +473,28 @@ static void push_ipv4(struct netpoll *np, struct sk_buff *skb, int len)
 	eth->h_proto = htons(ETH_P_IP);
 }

+static void push_udp(struct netpoll *np, struct sk_buff *skb, int len)
+{
+	struct udphdr *udph;
+	int udp_len;
+
+	udp_len = len + sizeof(struct udphdr);
+
+	skb_push(skb, sizeof(struct udphdr));
+	skb_reset_transport_header(skb);
+
+	udph = udp_hdr(skb);
+	udph->source = htons(np->local_port);
+	udph->dest = htons(np->remote_port);
+	udph->len = htons(udp_len);
+
+	netpoll_udp_checksum(np, skb, len);
+}
+
 int netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 {
 	int total_len, ip_len, udp_len;
 	struct sk_buff *skb;
-	struct udphdr *udph;
 	struct ethhdr *eth;

 	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
@@ -499,14 +516,7 @@ int netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 	skb_copy_to_linear_data(skb, msg, len);
 	skb_put(skb, len);

-	skb_push(skb, sizeof(struct udphdr));
-	skb_reset_transport_header(skb);
-	udph = udp_hdr(skb);
-	udph->source = htons(np->local_port);
-	udph->dest = htons(np->remote_port);
-	udph->len = htons(udp_len);
-
-	netpoll_udp_checksum(np, skb, len);
+	push_udp(np, skb, len);
 	if (np->ipv6)
 		push_ipv6(np, skb, len);
 	else

-- 
2.47.1