netpoll: Extract IPv6 address retrieval function

Extract the IPv6 address retrieval logic from netpoll_setup() into
a dedicated helper function netpoll_take_ipv6() to improve code
organization and readability.

The function handles obtaining the local IPv6 address from the
network device, including proper address type matching between
local and remote addresses (link-local vs global), and includes
appropriate error handling when IPv6 is not supported or no
suitable address is available.

Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250618-netpoll_ip_ref-v1-3-c2ac00fe558f@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 6ab494559b5c67e90d31177b217aa3d775cded01..7021ea45a0539b5329fbca0c21a8d4e366118dc5 100644 (file)
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -598,6 +598,47 @@ static void netpoll_wait_carrier(struct netpoll *np, struct net_device *ndev,
        }
 }
 
+/*
+ * Take the IPv6 from ndev and populate local_ip structure in netpoll
+ */
+static int netpoll_take_ipv6(struct netpoll *np, struct net_device *ndev)
+{
+       char buf[MAC_ADDR_STR_LEN + 1];
+       int err = -EDESTADDRREQ;
+       struct inet6_dev *idev;
+
+       if (!IS_ENABLED(CONFIG_IPV6)) {
+               np_err(np, "IPv6 is not supported %s, aborting\n",
+                      egress_dev(np, buf));
+               return -EINVAL;
+       }
+
+       idev = __in6_dev_get(ndev);
+       if (idev) {
+               struct inet6_ifaddr *ifp;
+
+               read_lock_bh(&idev->lock);
+               list_for_each_entry(ifp, &idev->addr_list, if_list) {
+                       if (!!(ipv6_addr_type(&ifp->addr) & IPV6_ADDR_LINKLOCAL) !=
+                               !!(ipv6_addr_type(&np->remote_ip.in6) & IPV6_ADDR_LINKLOCAL))
+                               continue;
+                       /* Got the IP, let's return */
+                       np->local_ip.in6 = ifp->addr;
+                       err = 0;
+                       break;
+               }
+               read_unlock_bh(&idev->lock);
+       }
+       if (err) {
+               np_err(np, "no IPv6 address for %s, aborting\n",
+                      egress_dev(np, buf));
+               return err;
+       }
+
+       np_info(np, "local IPv6 %pI6c\n", &np->local_ip.in6);
+       return 0;
+}
+
 /*
  * Take the IPv4 from ndev and populate local_ip structure in netpoll
  */
@@ -675,41 +716,12 @@ int netpoll_setup(struct netpoll *np)
                        err = netpoll_take_ipv4(np, ndev);
                        if (err)
                                goto put;
-                       ip_overwritten = true;
                } else {
-#if IS_ENABLED(CONFIG_IPV6)
-                       struct inet6_dev *idev;
-
-                       err = -EDESTADDRREQ;
-                       idev = __in6_dev_get(ndev);
-                       if (idev) {
-                               struct inet6_ifaddr *ifp;
-
-                               read_lock_bh(&idev->lock);
-                               list_for_each_entry(ifp, &idev->addr_list, if_list) {
-                                       if (!!(ipv6_addr_type(&ifp->addr) & IPV6_ADDR_LINKLOCAL) !=
-                                           !!(ipv6_addr_type(&np->remote_ip.in6) & IPV6_ADDR_LINKLOCAL))
-                                               continue;
-                                       np->local_ip.in6 = ifp->addr;
-                                       ip_overwritten = true;
-                                       err = 0;
-                                       break;
-                               }
-                               read_unlock_bh(&idev->lock);
-                       }
-                       if (err) {
-                               np_err(np, "no IPv6 address for %s, aborting\n",
-                                      egress_dev(np, buf));
+                       err = netpoll_take_ipv6(np, ndev);
+                       if (err)
                                goto put;
-                       } else
-                               np_info(np, "local IPv6 %pI6c\n", &np->local_ip.in6);
-#else
-                       np_err(np, "IPv6 is not supported %s, aborting\n",
-                              egress_dev(np, buf));
-                       err = -EINVAL;
-                       goto put;
-#endif
                }
+               ip_overwritten = true;
        }
 
        err = __netpoll_setup(np, ndev);