[PATCH 6.12.y 1/2] ipv6: annotate data-races around devconf->rpl_seg_enabled

[Sasha Levin <sashal@kernel.org>]

From: Yue Haibing <yuehaibing@huawei.com>

[ Upstream commit 3a5f55500f3e93cf4d62351c753452279b088b4b ]

devconf->rpl_seg_enabled can be changed concurrently from
/proc/sys/net/ipv6/conf, annotate lockless reads on it.

Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Link: https://patch.msgid.link/20250901123726.1972881-2-yuehaibing@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: f826df95332c ("ipv6: rpl: fix NULL dereference of idev in ipv6_rpl_srh_rcv()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/ipv6/exthdrs.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index e91afe5ec0b5d..e1e64e5507d22 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -504,10 +504,8 @@ static int ipv6_rpl_srh_rcv(struct sk_buff *skb)
 
 	idev = __in6_dev_get(skb->dev);
 
-	accept_rpl_seg = net->ipv6.devconf_all->rpl_seg_enabled;
-	if (accept_rpl_seg > idev->cnf.rpl_seg_enabled)
-		accept_rpl_seg = idev->cnf.rpl_seg_enabled;
-
+	accept_rpl_seg = min(READ_ONCE(net->ipv6.devconf_all->rpl_seg_enabled),
+			     READ_ONCE(idev->cnf.rpl_seg_enabled));
 	if (!accept_rpl_seg) {
 		kfree_skb(skb);
 		return -1;
-- 
2.53.0