net: introduce rcu_dereference_rtnl

We use rcu_dereference_check(p, rcu_read_lock_held() ||
lockdep_rtnl_is_held()) several times in network stack.

More usages to come too, so its time to create a helper.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index 58d44491880f..263690d991a8 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -749,6 +749,17 @@ extern int rtnl_is_locked(void);
 extern int lockdep_rtnl_is_held(void);
 #endif /* #ifdef CONFIG_PROVE_LOCKING */
 
+/**
+ * rcu_dereference_rtnl - rcu_dereference with debug checking
+ * @p: The pointer to read, prior to dereferencing
+ *
+ * Do an rcu_dereference(p), but check caller either holds rcu_read_lock()
+ * or RTNL
+ */
+#define rcu_dereference_rtnl(p)                                 \
+        rcu_dereference_check(p, rcu_read_lock_held() ||        \
+                                 lockdep_rtnl_is_held())
+
 extern void rtnetlink_init(void);
 extern void __rtnl_unlock(void);