[PATCH v2 net-next] ipv6: sit: Add ipip6_tunnel_dst_find() for cleanup
From: Yue Haibing <hidden>
Date: 2025-08-29 09:48:17
Extract the dst lookup logic from ipip6_tunnel_xmit() into new helper
ipip6_tunnel_dst_find() to reduce code duplication and enhance readability.
No functional change intended.
On a x86_64, with allmodconfig object size is also reduced:
./scripts/bloat-o-meter net/ipv6/sit.o net/ipv6/sit-new.o
add/remove: 5/3 grow/shrink: 3/4 up/down: 1841/-2275 (-434)
Function old new delta
ipip6_tunnel_dst_find - 1697 +1697
__pfx_ipip6_tunnel_dst_find - 64 +64
__UNIQUE_ID_modinfo2094 - 43 +43
ipip6_tunnel_xmit.isra.cold 79 88 +9
__UNIQUE_ID_modinfo2096 12 20 +8
__UNIQUE_ID___addressable_init_module2092 - 8 +8
__UNIQUE_ID___addressable_cleanup_module2093 - 8 +8
__func__ 55 59 +4
__UNIQUE_ID_modinfo2097 20 18 -2
__UNIQUE_ID___addressable_init_module2093 8 - -8
__UNIQUE_ID___addressable_cleanup_module2094 8 - -8
__UNIQUE_ID_modinfo2098 18 - -18
__UNIQUE_ID_modinfo2095 43 12 -31
descriptor 112 56 -56
ipip6_tunnel_xmit.isra 9910 7758 -2152
Total: Before=72537, After=72103, chg -0.60%
Signed-off-by: Yue Haibing <redacted>
---
v2: add newlines before return in ipip6_tunnel_dst_find()
add bloat-o-meter info in commit log
---
net/ipv6/sit.c | 95 ++++++++++++++++++++++++--------------------------
1 file changed, 45 insertions(+), 50 deletions(-)
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 12496ba1b7d4..60bd7f01fa09 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c@@ -848,6 +848,49 @@ static inline __be32 try_6rd(struct ip_tunnel *tunnel, return dst; } +static bool ipip6_tunnel_dst_find(struct sk_buff *skb, __be32 *dst, + bool is_isatap) +{ + const struct ipv6hdr *iph6 = ipv6_hdr(skb); + struct neighbour *neigh = NULL; + const struct in6_addr *addr6; + bool found = false; + int addr_type; + + if (skb_dst(skb)) + neigh = dst_neigh_lookup(skb_dst(skb), &iph6->daddr); + + if (!neigh) { + net_dbg_ratelimited("nexthop == NULL\n"); + return false; + } + + addr6 = (const struct in6_addr *)&neigh->primary_key; + addr_type = ipv6_addr_type(addr6); + + if (is_isatap) { + if ((addr_type & IPV6_ADDR_UNICAST) && + ipv6_addr_is_isatap(addr6)) { + *dst = addr6->s6_addr32[3]; + found = true; + } + } else { + if (addr_type == IPV6_ADDR_ANY) { + addr6 = &ipv6_hdr(skb)->daddr; + addr_type = ipv6_addr_type(addr6); + } + + if ((addr_type & IPV6_ADDR_COMPATv4) != 0) { + *dst = addr6->s6_addr32[3]; + found = true; + } + } + + neigh_release(neigh); + + return found; +} + /* * This function assumes it is being called from dev_queue_xmit() * and that skb is filled properly by that function.
@@ -867,8 +910,6 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb, __be32 dst = tiph->daddr; struct flowi4 fl4; int mtu; - const struct in6_addr *addr6; - int addr_type; u8 ttl; u8 protocol = IPPROTO_IPV6; int t_hlen = tunnel->hlen + sizeof(struct iphdr);
@@ -878,28 +919,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb, /* ISATAP (RFC4214) - must come before 6to4 */ if (dev->priv_flags & IFF_ISATAP) { - struct neighbour *neigh = NULL; - bool do_tx_error = false; - - if (skb_dst(skb)) - neigh = dst_neigh_lookup(skb_dst(skb), &iph6->daddr); - - if (!neigh) { - net_dbg_ratelimited("nexthop == NULL\n"); - goto tx_error; - } - - addr6 = (const struct in6_addr *)&neigh->primary_key; - addr_type = ipv6_addr_type(addr6); - - if ((addr_type & IPV6_ADDR_UNICAST) && - ipv6_addr_is_isatap(addr6)) - dst = addr6->s6_addr32[3]; - else - do_tx_error = true; - - neigh_release(neigh); - if (do_tx_error) + if (!ipip6_tunnel_dst_find(skb, &dst, true)) goto tx_error; }
@@ -907,32 +927,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb, dst = try_6rd(tunnel, &iph6->daddr); if (!dst) { - struct neighbour *neigh = NULL; - bool do_tx_error = false; - - if (skb_dst(skb)) - neigh = dst_neigh_lookup(skb_dst(skb), &iph6->daddr); - - if (!neigh) { - net_dbg_ratelimited("nexthop == NULL\n"); - goto tx_error; - } - - addr6 = (const struct in6_addr *)&neigh->primary_key; - addr_type = ipv6_addr_type(addr6); - - if (addr_type == IPV6_ADDR_ANY) { - addr6 = &ipv6_hdr(skb)->daddr; - addr_type = ipv6_addr_type(addr6); - } - - if ((addr_type & IPV6_ADDR_COMPATv4) != 0) - dst = addr6->s6_addr32[3]; - else - do_tx_error = true; - - neigh_release(neigh); - if (do_tx_error) + if (!ipip6_tunnel_dst_find(skb, &dst, false)) goto tx_error; }
--
2.34.1