rtnetlink: Add assertion helpers for per-netns RTNL.

Once an RTNL scope is converted with rtnl_net_lock(), we will replace
RTNL helper functions inside the scope with the following per-netns
alternatives:

  ASSERT_RTNL()           -> ASSERT_RTNL_NET(net)
  rcu_dereference_rtnl(p) -> rcu_dereference_rtnl_net(net, p)

Note that the per-netns helpers are equivalent to the conventional
helpers unless CONFIG_DEBUG_NET_SMALL_RTNL is enabled.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index edd840a49989c670f1aa58ae9f5779220aa4b829..8468a4ce8510eafc98e94b2aacf9756fe3bf0dad 100644 (file)
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -51,6 +51,10 @@ extern atomic_t dev_unreg_count;
 extern struct rw_semaphore pernet_ops_rwsem;
 extern struct rw_semaphore net_rwsem;
 
+#define ASSERT_RTNL() \
+       WARN_ONCE(!rtnl_is_locked(), \
+                 "RTNL: assertion failed at %s (%d)\n", __FILE__,  __LINE__)
+
 #ifdef CONFIG_PROVE_LOCKING
 extern bool lockdep_rtnl_is_held(void);
 #else
@@ -98,6 +102,22 @@ void __rtnl_net_unlock(struct net *net);
 void rtnl_net_lock(struct net *net);
 void rtnl_net_unlock(struct net *net);
 int rtnl_net_lock_cmp_fn(const struct lockdep_map *a, const struct lockdep_map *b);
+
+bool rtnl_net_is_locked(struct net *net);
+
+#define ASSERT_RTNL_NET(net)                                           \
+       WARN_ONCE(!rtnl_net_is_locked(net),                             \
+                 "RTNL_NET: assertion failed at %s (%d)\n",            \
+                 __FILE__,  __LINE__)
+
+bool lockdep_rtnl_net_is_held(struct net *net);
+
+#define rcu_dereference_rtnl_net(net, p)                               \
+       rcu_dereference_check(p, lockdep_rtnl_net_is_held(net))
+#define rtnl_net_dereference(net, p)                                   \
+       rcu_dereference_protected(p, lockdep_rtnl_net_is_held(net))
+#define rcu_replace_pointer_rtnl_net(net, rp, p)                       \
+       rcu_replace_pointer(rp, p, lockdep_rtnl_net_is_held(net))
 #else
 static inline void __rtnl_net_lock(struct net *net) {}
 static inline void __rtnl_net_unlock(struct net *net) {}
@@ -111,6 +131,27 @@ static inline void rtnl_net_unlock(struct net *net)
 {
        rtnl_unlock();
 }
+
+static inline void ASSERT_RTNL_NET(struct net *net)
+{
+       ASSERT_RTNL();
+}
+
+static inline void *rcu_dereference_rtnl_net(struct net *net, void *p)
+{
+       return rcu_dereference_rtnl(p);
+}
+
+static inline void *rtnl_net_dereference(struct net *net, void *p)
+{
+       return rtnl_dereference(p);
+}
+
+static inline void *rcu_replace_pointer_rtnl_net(struct net *net,
+                                                void *rp, void *p)
+{
+       return rcu_replace_pointer_rtnl(rp, p);
+}
 #endif
 
 static inline struct netdev_queue *dev_ingress_queue(struct net_device *dev)
@@ -140,10 +181,6 @@ void rtnetlink_init(void);
 void __rtnl_unlock(void);
 void rtnl_kfree_skbs(struct sk_buff *head, struct sk_buff *tail);
 
-#define ASSERT_RTNL() \
-       WARN_ONCE(!rtnl_is_locked(), \
-                 "RTNL: assertion failed at %s (%d)\n", __FILE__,  __LINE__)
-
 extern int ndo_dflt_fdb_dump(struct sk_buff *skb,
                             struct netlink_callback *cb,
                             struct net_device *dev,

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 46567fa54e42eb1ea57088da119ceb9ca7ffa1e7..6d68247aea70e311a09669013126f3de8a68c916 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -235,6 +235,18 @@ int rtnl_net_lock_cmp_fn(const struct lockdep_map *a, const struct lockdep_map *
 
        return rtnl_net_cmp_locks(net_a, net_b);
 }
+
+bool rtnl_net_is_locked(struct net *net)
+{
+       return rtnl_is_locked() && mutex_is_locked(&net->rtnl_mutex);
+}
+EXPORT_SYMBOL(rtnl_net_is_locked);
+
+bool lockdep_rtnl_net_is_held(struct net *net)
+{
+       return lockdep_rtnl_is_held() && lockdep_is_held(&net->rtnl_mutex);
+}
+EXPORT_SYMBOL(lockdep_rtnl_net_is_held);
 #endif
 
 static struct rtnl_link __rcu *__rcu *rtnl_msg_handlers[RTNL_FAMILY_MAX + 1];