netdev - [PATCH net-next] ndisc: ndisc_send

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Message-ID: <20250214140705.2105890-1-edumazet@google.com>
Date: Fri, 14 Feb 2025 14:07:05 +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: netdev@...r.kernel.org, David Ahern <dsahern@...nel.org>, 
	Simon Horman <horms@...nel.org>, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next] ndisc: ndisc_send_redirect() cleanup

ndisc_send_redirect() is always called under rcu_read_lock().

It can use dev_net_rcu() and avoid one redundant
rcu_read_lock()/rcu_read_unlock() pair.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv6/ndisc.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 8699d1a188dc4a15ac0b65229c4dd19240c9c054..ecb5c4b8518fdd72d0e89640641ec917743e9c72 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1680,7 +1680,7 @@ static void ndisc_fill_redirect_hdr_option(struct sk_buff *skb,
 void ndisc_send_redirect(struct sk_buff *skb, const struct in6_addr *target)
 {
 	struct net_device *dev = skb->dev;
-	struct net *net = dev_net(dev);
+	struct net *net = dev_net_rcu(dev);
 	struct sock *sk = net->ipv6.ndisc_sk;
 	int optlen = 0;
 	struct inet_peer *peer;
@@ -1695,8 +1695,8 @@ void ndisc_send_redirect(struct sk_buff *skb, const struct in6_addr *target)
 	   ops_data_buf[NDISC_OPS_REDIRECT_DATA_SPACE], *ops_data = NULL;
 	bool ret;
 
-	if (netif_is_l3_master(skb->dev)) {
-		dev = dev_get_by_index_rcu(dev_net(skb->dev), IPCB(skb)->iif);
+	if (netif_is_l3_master(dev)) {
+		dev = dev_get_by_index_rcu(net, IPCB(skb)->iif);
 		if (!dev)
 			return;
 	}
@@ -1734,10 +1734,8 @@ void ndisc_send_redirect(struct sk_buff *skb, const struct in6_addr *target)
 		goto release;
 	}
 
-	rcu_read_lock();
 	peer = inet_getpeer_v6(net->ipv6.peers, &ipv6_hdr(skb)->saddr);
 	ret = inet_peer_xrlim_allow(peer, 1*HZ);
-	rcu_read_unlock();
 
 	if (!ret)
 		goto release;
-- 
2.48.1.601.g30ceb7b040-goog