netdev - [PATCH v2 net-next 12/15] ipv6: addrconf_disable

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Date: Tue, 27 Feb 2024 15:01:57 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: David Ahern <dsahern@...nel.org>, Jiri Pirko <jiri@...dia.com>, netdev@...r.kernel.org, 
	eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH v2 net-next 12/15] ipv6: addrconf_disable_policy() optimization

Writing over /proc/sys/net/ipv6/conf/default/disable_policy
does not need to hold RTNL.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv6/addrconf.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 392e64df991a4005736883af128cd82ac3895167..d198365b1ac669a1158c44c1c9d050ede276d638 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -6691,20 +6691,19 @@ void addrconf_disable_policy_idev(struct inet6_dev *idev, int val)
 static
 int addrconf_disable_policy(struct ctl_table *ctl, int *valp, int val)
 {
+	struct net *net = (struct net *)ctl->extra2;
 	struct inet6_dev *idev;
-	struct net *net;
+
+	if (valp == &net->ipv6.devconf_dflt->disable_policy) {
+		WRITE_ONCE(*valp, val);
+		return 0;
+	}
 
 	if (!rtnl_trylock())
 		return restart_syscall();
 
 	WRITE_ONCE(*valp, val);
 
-	net = (struct net *)ctl->extra2;
-	if (valp == &net->ipv6.devconf_dflt->disable_policy) {
-		rtnl_unlock();
-		return 0;
-	}
-
 	if (valp == &net->ipv6.devconf_all->disable_policy)  {
 		struct net_device *dev;
 
-- 
2.44.0.rc1.240.g4c46232300-goog