[PATCH net-next v3 8/9] ip6_gre: make prepare_ip6gre_xmit_other() void

[Anton Danilov <littlesmilingcloud@gmail.com>]

prepare_ip6gre_xmit_other() copies the flow template of the tunnel and
picks up its encapsulation limit, DS field and mark.  Unlike its IPv6
sibling, which fails when the tunnel encapsulation limit option leaves
no room for another header, it has nothing to fail on: its only return
statement is "return 0", and it has been that way since the function
was added by commit 41337f52b967 ("ip6_gre: set DSCP for non-IP").  Its
caller still checks the result and bails out on a branch that never
runs.

Make it void and drop the check, the way prepare_ip6gre_xmit_ipv4() is
already called.  The next patch gives every failing branch of the
transmit path a drop reason, and this one would otherwise get a reason
it can never report.

Assisted-by: Claude-Code:claude-fable-5-1
Signed-off-by: Anton Danilov <littlesmilingcloud@gmail.com>
---
 net/ipv6/ip6_gre.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 0b270f4ac774..e7d0fe4570e4 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -693,10 +693,10 @@ static int prepare_ip6gre_xmit_ipv6(struct sk_buff *skb,
 	return 0;
 }
 
-static int prepare_ip6gre_xmit_other(struct sk_buff *skb,
-				     struct net_device *dev,
-				     struct flowi6 *fl6, __u8 *dsfield,
-				     int *encap_limit)
+static void prepare_ip6gre_xmit_other(struct sk_buff *skb,
+				      struct net_device *dev,
+				      struct flowi6 *fl6, __u8 *dsfield,
+				      int *encap_limit)
 {
 	struct ip6_tnl *t = netdev_priv(dev);
 
@@ -716,8 +716,6 @@ static int prepare_ip6gre_xmit_other(struct sk_buff *skb,
 		fl6->flowi6_mark = t->parms.fwmark;
 
 	fl6->flowi6_uid = sock_net_uid(dev_net(dev), NULL);
-
-	return 0;
 }
 
 static struct ip_tunnel_info *skb_tunnel_info_txcheck(struct sk_buff *skb)
@@ -878,9 +876,9 @@ static int ip6gre_xmit_other(struct sk_buff *skb, struct net_device *dev)
 	__u32 mtu;
 	int err;
 
-	if (!t->parms.collect_md &&
-	    prepare_ip6gre_xmit_other(skb, dev, &fl6, &dsfield, &encap_limit))
-		return -1;
+	if (!t->parms.collect_md)
+		prepare_ip6gre_xmit_other(skb, dev, &fl6,
+					  &dsfield, &encap_limit);
 
 	err = gre_handle_offloads(skb, test_bit(IP_TUNNEL_CSUM_BIT,
 						t->parms.o_flags));
-- 
2.47.3