net: sched: RCU cls_tcindex

Make cls_tcindex RCU safe.

This patch addds a new RCU routine rcu_dereference_bh_rtnl() to check
caller either holds the rcu read lock or RTNL. This is needed to
handle the case where tcindex_lookup() is being called in both cases.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/rtnetlink.h

@@ -46,6 +46,16 @@ static inline int lockdep_rtnl_is_held(void)
 #define rcu_dereference_rtnl(p)					\
 	rcu_dereference_check(p, lockdep_rtnl_is_held())
 
+/**
+ * rcu_dereference_bh_rtnl - rcu_dereference_bh with debug checking
+ * @p: The pointer to read, prior to dereference
+ *
+ * Do an rcu_dereference_bh(p), but check caller either holds rcu_read_lock_bh()
+ * or RTNL. Note : Please prefer rtnl_dereference() or rcu_dereference_bh()
+ */
+#define rcu_dereference_bh_rtnl(p)				\
+	rcu_dereference_bh_check(p, lockdep_rtnl_is_held())
+
 /**
  * rtnl_dereference - fetch RCU pointer when updates are prevented by RTNL
  * @p: The pointer to read, prior to dereferencing