linux-kernel - [PATCH net-next v2 6/7] netpoll: move Ethernet setup to push

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Message-Id: <20250702-netpoll_untagle_ip-v2-6-13cf3db24e2b@debian.org>
Date: Wed, 02 Jul 2025 03:06:38 -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 6/7] netpoll: move Ethernet setup to push_eth()
 helper

Refactor Ethernet header population into dedicated function, completing
the layered abstraction with:

- push_eth() for link layer
- push_udp() for transport
- push_ipv4()/push_ipv6() for network

Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 net/core/netpoll.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 70035e27d91cc..a1da97b5b30b6 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -417,7 +417,6 @@ EXPORT_SYMBOL(netpoll_send_skb);
 static void push_ipv6(struct netpoll *np, struct sk_buff *skb, int len)
 {
 	struct ipv6hdr *ip6h;
-	struct ethhdr *eth;
 
 	skb_push(skb, sizeof(struct ipv6hdr));
 	skb_reset_network_header(skb);
@@ -435,16 +434,12 @@ static void push_ipv6(struct netpoll *np, struct sk_buff *skb, int len)
 	ip6h->saddr = np->local_ip.in6;
 	ip6h->daddr = np->remote_ip.in6;
 
-	eth = skb_push(skb, ETH_HLEN);
-	skb_reset_mac_header(skb);
 	skb->protocol = htons(ETH_P_IPV6);
-	eth->h_proto = htons(ETH_P_IPV6);
 }
 
 static void push_ipv4(struct netpoll *np, struct sk_buff *skb, int len)
 {
 	static atomic_t ip_ident;
-	struct ethhdr *eth;
 	struct iphdr *iph;
 	int ip_len;
 
@@ -466,11 +461,7 @@ static void push_ipv4(struct netpoll *np, struct sk_buff *skb, int len)
 	put_unaligned(np->local_ip.ip, &iph->saddr);
 	put_unaligned(np->remote_ip.ip, &iph->daddr);
 	iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
-
-	eth = skb_push(skb, ETH_HLEN);
-	skb_reset_mac_header(skb);
 	skb->protocol = htons(ETH_P_IP);
-	eth->h_proto = htons(ETH_P_IP);
 }
 
 static void push_udp(struct netpoll *np, struct sk_buff *skb, int len)
@@ -491,11 +482,24 @@ static void push_udp(struct netpoll *np, struct sk_buff *skb, int len)
 	netpoll_udp_checksum(np, skb, len);
 }
 
+static void push_eth(struct netpoll *np, struct sk_buff *skb)
+{
+	struct ethhdr *eth;
+
+	eth = skb_push(skb, ETH_HLEN);
+	skb_reset_mac_header(skb);
+	ether_addr_copy(eth->h_source, np->dev->dev_addr);
+	ether_addr_copy(eth->h_dest, np->remote_mac);
+	if (np->ipv6)
+		eth->h_proto = htons(ETH_P_IPV6);
+	else
+		eth->h_proto = htons(ETH_P_IP);
+}
+
 int netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 {
 	int total_len, ip_len, udp_len;
 	struct sk_buff *skb;
-	struct ethhdr *eth;
 
 	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
 		WARN_ON_ONCE(!irqs_disabled());
@@ -521,11 +525,7 @@ int netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 		push_ipv6(np, skb, len);
 	else
 		push_ipv4(np, skb, len);
-
-	eth = eth_hdr(skb);
-	ether_addr_copy(eth->h_source, np->dev->dev_addr);
-	ether_addr_copy(eth->h_dest, np->remote_mac);
-
+	push_eth(np, skb);
 	skb->dev = np->dev;
 
 	return (int)netpoll_send_skb(np, skb);

-- 
2.47.1