netdev - [PATCH net-next v2 1/4] net/ipv6: flatten ip6_route_get

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Message-ID: <20250724150042.6361-2-equinox@diac24.net>
Date: Thu, 24 Jul 2025 17:00:38 +0200
From: David Lamparter <equinox@...c24.net>
To: netdev@...r.kernel.org,
	David Ahern <dsahern@...nel.org>,
	"David S. Miller" <davem@...emloft.net>
Cc: David Lamparter <equinox@...c24.net>,
	Lorenzo Colitti <lorenzo@...gle.com>,
	Patrick Rohr <prohr@...gle.com>
Subject: [PATCH net-next v2 1/4] net/ipv6: flatten ip6_route_get_saddr

Inline ip6_route_get_saddr()'s functionality in rt6_fill_node(), to
prepare for replacing the former with a dst based function.

NB: the l3mdev handling introduced by 252442f2ae31 "ipv6: fix source
address selection with route leak" is dropped here - the l3mdev ifindex
was a constant 0 on this call site, so that code was in fact dead.

Signed-off-by: David Lamparter <equinox@...c24.net>
---
 net/ipv6/route.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 3fbe0885c21c..a2362913ebed 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -5821,9 +5821,19 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
 			if (nla_put_u32(skb, RTA_IIF, iif))
 				goto nla_put_failure;
 	} else if (dest) {
-		struct in6_addr saddr_buf;
-		if (ip6_route_get_saddr(net, rt, dest, 0, 0, &saddr_buf) == 0 &&
-		    nla_put_in6_addr(skb, RTA_PREFSRC, &saddr_buf))
+		struct in6_addr saddr_buf, *saddr = NULL;
+
+		if (rt->fib6_prefsrc.plen) {
+			saddr = &rt->fib6_prefsrc.addr;
+		} else {
+			struct net_device *dev = fib6_info_nh_dev(rt);
+
+			if (ipv6_dev_get_saddr(net, dev, dest, 0,
+					       &saddr_buf) == 0)
+				saddr = &saddr_buf;
+		}
+
+		if (saddr && nla_put_in6_addr(skb, RTA_PREFSRC, saddr))
 			goto nla_put_failure;
 	}
 
-- 
2.47.2