netpoll: extract IPv4 address retrieval into helper function

[ Upstream commit 3699f99 ]

Move the IPv4 address retrieval logic from netpoll_setup() into a
separate netpoll_take_ipv4() function to improve code organization
and readability. This change consolidates the IPv4-specific logic
and error handling into a dedicated function while maintaining
the same functionality.

No functional changes.

Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250618-netpoll_ip_ref-v1-2-c2ac00fe558f@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 3bc179b ("netpoll: fix IPv6 local-address corruption")
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: leitao

net/core/netpoll.c

@@ -721,13 +721,41 @@ static void netpoll_wait_carrier(struct netpoll *np, struct net_device *ndev,
 	}
 }
 
+/*
+ * Take the IPv4 from ndev and populate local_ip structure in netpoll
+ */
+static int netpoll_take_ipv4(struct netpoll *np, struct net_device *ndev)
+{
+	char buf[MAC_ADDR_STR_LEN + 1];
+	const struct in_ifaddr *ifa;
+	struct in_device *in_dev;
+
+	in_dev = __in_dev_get_rtnl(ndev);
+	if (!in_dev) {
+		np_err(np, "no IP address for %s, aborting\n",
+		       egress_dev(np, buf));
+		return -EDESTADDRREQ;
+	}
+
+	ifa = rtnl_dereference(in_dev->ifa_list);
+	if (!ifa) {
+		np_err(np, "no IP address for %s, aborting\n",
+		       egress_dev(np, buf));
+		return -EDESTADDRREQ;
+	}
+
+	np->local_ip.ip = ifa->ifa_local;
+	np_info(np, "local IP %pI4\n", &np->local_ip.ip);
+
+	return 0;
+}
+
 int netpoll_setup(struct netpoll *np)
 {
 	struct net *net = current->nsproxy->net_ns;
 	char buf[MAC_ADDR_STR_LEN + 1];
 	struct net_device *ndev = NULL;
 	bool ip_overwritten = false;
-	struct in_device *in_dev;
 	int err;
 
 	rtnl_lock();
@@ -767,24 +795,10 @@ int netpoll_setup(struct netpoll *np)
 
 	if (!np->local_ip.ip) {
 		if (!np->ipv6) {
-			const struct in_ifaddr *ifa;
-
-			in_dev = __in_dev_get_rtnl(ndev);
-			if (!in_dev)
-				goto put_noaddr;
-
-			ifa = rtnl_dereference(in_dev->ifa_list);
-			if (!ifa) {
-put_noaddr:
-				np_err(np, "no IP address for %s, aborting\n",
-				       egress_dev(np, buf));
-				err = -EDESTADDRREQ;
+			err = netpoll_take_ipv4(np, ndev);
+			if (err)
 				goto put;
-			}
-
-			np->local_ip.ip = ifa->ifa_local;
 			ip_overwritten = true;
-			np_info(np, "local IP %pI4\n", &np->local_ip.ip);
 		} else {
 #if IS_ENABLED(CONFIG_IPV6)
 			struct inet6_dev *idev;