net: add dev_net_rcu() helper

[ Upstream commit 482ad2a4ace2740ca0ff1cbc8f3c7f862f3ab507 ]

dev->nd_net can change, readers should either
use rcu_read_lock() or RTNL.

We currently use a generic helper, dev_net() with
no debugging support. We probably have many hidden bugs.

Add dev_net_rcu() helper for callers using rcu_read_lock()
protection.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250205155120.1676781-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: dd205fcc33d9 ("ipv4: use RCU protection in rt_is_expired()")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 829ebde5d50d5b998ac94e6a68cf6df9bc06f229..79b528c128c1486919b9578953fb942dde947cab 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2454,6 +2454,12 @@ struct net *dev_net(const struct net_device *dev)
        return read_pnet(&dev->nd_net);
 }
 
+static inline
+struct net *dev_net_rcu(const struct net_device *dev)
+{
+       return read_pnet_rcu(&dev->nd_net);
+}
+
 static inline
 void dev_net_set(struct net_device *dev, struct net *net)
 {

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 0b6bea456fce67386343f516e1b53fdf928e43d0..ff9ecc76d622b568512e19b19ff0cb7b54d8f834 100644 (file)
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -336,7 +336,7 @@ static inline struct net *read_pnet(const possible_net_t *pnet)
 #endif
 }
 
-static inline struct net *read_pnet_rcu(possible_net_t *pnet)
+static inline struct net *read_pnet_rcu(const possible_net_t *pnet)
 {
 #ifdef CONFIG_NET_NS
        return rcu_dereference(pnet->net);