[PATCH 6.6.y 1/3] net: Add net_passive_inc() and net_passive_dec().

[Sasha Levin <sashal@kernel.org>]

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit e57a6320215c3967f51ab0edeff87db2095440e4 ]

net_drop_ns() is NULL when CONFIG_NET_NS is disabled.

The next patch introduces a function that increments
and decrements net->passive.

As a prep, let's rename and export net_free() to
net_passive_dec() and add net_passive_inc().

Suggested-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/netdev/CANn89i+oUCt2VGvrbrweniTendZFEh+nwS=uonc004-aPkWy-Q@mail.gmail.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250217191129.19967-2-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 59b33fab4ca4 ("smb: client: fix netns refcount leak after net_passive changes")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/net/net_namespace.h | 16 ++++++++++++++++
 net/core/net_namespace.c    |  8 ++++----
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index ce3f84c6eb8e..5ddcadee62b7 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -293,6 +293,7 @@ static inline int check_net(const struct net *net)
 }
 
 void net_drop_ns(void *);
+void net_passive_dec(struct net *net);
 
 #else
 
@@ -322,8 +323,23 @@ static inline int check_net(const struct net *net)
 }
 
 #define net_drop_ns NULL
+
+static inline void net_passive_dec(struct net *net)
+{
+	refcount_dec(&net->passive);
+}
 #endif
 
+static inline void net_passive_inc(struct net *net)
+{
+	refcount_inc(&net->passive);
+}
+
+/* Returns true if the netns initialization is completed successfully */
+static inline bool net_initialized(const struct net *net)
+{
+	return READ_ONCE(net->list.next);
+}
 
 static inline void __netns_tracker_alloc(struct net *net,
 					 netns_tracker *tracker,
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 70ac9d9bc877..20829e0c36cd 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -467,7 +467,7 @@ static void net_complete_free(void)
 
 }
 
-static void net_free(struct net *net)
+void net_passive_dec(struct net *net)
 {
 	if (refcount_dec_and_test(&net->passive)) {
 		kfree(rcu_access_pointer(net->gen));
@@ -485,7 +485,7 @@ void net_drop_ns(void *p)
 	struct net *net = (struct net *)p;
 
 	if (net)
-		net_free(net);
+		net_passive_dec(net);
 }
 
 struct net *copy_net_ns(unsigned long flags,
@@ -527,7 +527,7 @@ struct net *copy_net_ns(unsigned long flags,
 		key_remove_domain(net->key_domain);
 #endif
 		put_user_ns(user_ns);
-		net_free(net);
+		net_passive_dec(net);
 dec_ucounts:
 		dec_net_namespaces(ucounts);
 		return ERR_PTR(rv);
@@ -672,7 +672,7 @@ static void cleanup_net(struct work_struct *work)
 		key_remove_domain(net->key_domain);
 #endif
 		put_user_ns(net->user_ns);
-		net_free(net);
+		net_passive_dec(net);
 	}
 }
 
-- 
2.39.5