netdev - [PATCH net 05/16] ipv4: use RCU protection in rt_is

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Message-ID: <20250131171334.1172661-6-edumazet@google.com>
Date: Fri, 31 Jan 2025 17:13:23 +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, Kuniyuki Iwashima <kuniyu@...zon.com>, 
	Simon Horman <horms@...nel.org>, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net 05/16] ipv4: use RCU protection in rt_is_expired()

rt_is_expired() must use RCU protection to make
sure the net structure it reads does not disappear.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/route.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 74c074f45758be5ae78a87edb31837481cc40278..e959327c0ba8979ce5c7ca8c46ae41068824edc6 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -390,7 +390,13 @@ static inline int ip_rt_proc_init(void)
 
 static inline bool rt_is_expired(const struct rtable *rth)
 {
-	return rth->rt_genid != rt_genid_ipv4(dev_net(rth->dst.dev));
+	bool res;
+
+	rcu_read_lock();
+	res = rth->rt_genid != rt_genid_ipv4(dev_net_rcu(rth->dst.dev));
+	rcu_read_unlock();
+
+	return res;
 }
 
 void rt_cache_flush(struct net *net)
-- 
2.48.1.362.g079036d154-goog