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: 71b8471c93fa ("ipv4: use RCU protection in ipv4_default_advmss()")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 02d3bafebbe77c61bd607433da4cdc666a0f36f7..4f17b786828af778e27ef8b095538b8e86fd5166 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2577,6 +2577,12 @@ 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 9398c8f49953684a674b9465c49b007c03943743..da93873df4dbd73e8141e0edbc8f2f666105406a 100644 (file)
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -387,7 +387,7 @@ 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);