net: sched: extend proto ops to support unlocked classifiers

Add 'rtnl_held' flag to tcf proto change, delete, destroy, dump, walk
functions to track rtnl lock status. Extend users of these function in cls
API to propagate rtnl lock status to them. This allows classifiers to
obtain rtnl lock when necessary and to pass rtnl lock status to extensions
and driver offload callbacks.

Add flags field to tcf proto ops. Add flag value to indicate that
classifier doesn't require rtnl lock.

Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/pkt_cls.h

@@ -47,7 +47,7 @@ void tcf_chain_put_by_act(struct tcf_chain *chain);
 struct tcf_chain *tcf_get_next_chain(struct tcf_block *block,
 				     struct tcf_chain *chain);
 struct tcf_proto *tcf_get_next_proto(struct tcf_chain *chain,
-				     struct tcf_proto *tp);
+				     struct tcf_proto *tp, bool rtnl_held);
 void tcf_block_netif_keep_dst(struct tcf_block *block);
 int tcf_block_get(struct tcf_block **p_block,
 		  struct tcf_proto __rcu **p_filter_chain, struct Qdisc *q,

include/net/sch_generic.h

@@ -273,20 +273,21 @@ struct tcf_proto_ops {
 					    const struct tcf_proto *,
 					    struct tcf_result *);
 	int			(*init)(struct tcf_proto*);
-	void			(*destroy)(struct tcf_proto *tp,
+	void			(*destroy)(struct tcf_proto *tp, bool rtnl_held,
 					   struct netlink_ext_ack *extack);
 
 	void*			(*get)(struct tcf_proto*, u32 handle);
 	void			(*put)(struct tcf_proto *tp, void *f);
 	int			(*change)(struct net *net, struct sk_buff *,
 					struct tcf_proto*, unsigned long,
 					u32 handle, struct nlattr **,
-					void **, bool,
+					void **, bool, bool,
 					struct netlink_ext_ack *);
 	int			(*delete)(struct tcf_proto *tp, void *arg,
-					  bool *last,
+					  bool *last, bool rtnl_held,
 					  struct netlink_ext_ack *);
-	void			(*walk)(struct tcf_proto*, struct tcf_walker *arg);
+	void			(*walk)(struct tcf_proto *tp,
+					struct tcf_walker *arg, bool rtnl_held);
 	int			(*reoffload)(struct tcf_proto *tp, bool add,
 					     tc_setup_cb_t *cb, void *cb_priv,
 					     struct netlink_ext_ack *extack);
@@ -299,12 +300,18 @@ struct tcf_proto_ops {
 
 	/* rtnetlink specific */
 	int			(*dump)(struct net*, struct tcf_proto*, void *,
-					struct sk_buff *skb, struct tcmsg*);
+					struct sk_buff *skb, struct tcmsg*,
+					bool);
 	int			(*tmplt_dump)(struct sk_buff *skb,
 					      struct net *net,
 					      void *tmplt_priv);
 
 	struct module		*owner;
+	int			flags;
+};
+
+enum tcf_proto_ops_flags {
+	TCF_PROTO_OPS_DOIT_UNLOCKED = 1,
 };
 
 struct tcf_proto {