Merge branch 'rtnetlink-refactor-rtnl_-new-del-set-link-for-per-netns-rtnl'

Kuniyuki Iwashima says:

====================
rtnetlink: Refactor rtnl_{new,del,set}link() for per-netns RTNL.

This is a prep for the next series where we will push RTNL down to
rtnl_{new,del,set}link().

That means, for example, __rtnl_newlink() is always under RTNL, but
rtnl_newlink() has a non-RTNL section.

As a prerequisite for per-netns RTNL, we will move netns validation
(and RTNL-independent validations if possible) to that section.

rtnl_link_ops and rtnl_af_ops will be protected with SRCU not to
depend on RTNL.

Changes:
  v2:
    * Add Eric's Reviewed-by to patch 1-4,6,8-11, (no tag on 5,7,12-14)
    * Patch 7
      * Handle error of init_srcu_struct().
      * Call cleanup_srcu_struct() after synchronize_srcu().
    * Patch 12
      * Move put_net() before errorout label
    * Patch 13
      * Newly added as prep for patch 14
    * Patch 14
      * Handle error of init_srcu_struct().
      * Call cleanup_srcu_struct() after synchronize_srcu().

  v1: https://lore.kernel.org/netdev/[email protected]/
====================

Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>

Author: Paolo Abeni

include/net/rtnetlink.h

@@ -3,6 +3,7 @@
 #define __NET_RTNETLINK_H
 
 #include <linux/rtnetlink.h>
+#include <linux/srcu.h>
 #include <net/netlink.h>
 
 typedef int (*rtnl_doit_func)(struct sk_buff *, struct nlmsghdr *,
@@ -69,7 +70,8 @@ static inline int rtnl_msg_family(const struct nlmsghdr *nlh)
 /**
  *	struct rtnl_link_ops - rtnetlink link operations
  *
- *	@list: Used internally
+ *	@list: Used internally, protected by RTNL and SRCU
+ *	@srcu: Used internally
  *	@kind: Identifier
  *	@netns_refund: Physical device, move to init_net on netns exit
  *	@maxtype: Highest device specific netlink attribute number
@@ -100,6 +102,7 @@ static inline int rtnl_msg_family(const struct nlmsghdr *nlh)
  */
 struct rtnl_link_ops {
 	struct list_head	list;
+	struct srcu_struct	srcu;
 
 	const char		*kind;
 
@@ -169,7 +172,8 @@ void rtnl_link_unregister(struct rtnl_link_ops *ops);
 /**
  * 	struct rtnl_af_ops - rtnetlink address family operations
  *
- *	@list: Used internally
+ *	@list: Used internally, protected by RTNL and SRCU
+ *	@srcu: Used internally
  * 	@family: Address family
  * 	@fill_link_af: Function to fill IFLA_AF_SPEC with address family
  * 		       specific netlink attributes.
@@ -182,6 +186,8 @@ void rtnl_link_unregister(struct rtnl_link_ops *ops);
  */
 struct rtnl_af_ops {
 	struct list_head	list;
+	struct srcu_struct	srcu;
+
 	int			family;
 
 	int			(*fill_link_af)(struct sk_buff *skb,
@@ -201,7 +207,7 @@ struct rtnl_af_ops {
 	size_t			(*get_stats_af_size)(const struct net_device *dev);
 };
 
-void rtnl_af_register(struct rtnl_af_ops *ops);
+int rtnl_af_register(struct rtnl_af_ops *ops);
 void rtnl_af_unregister(struct rtnl_af_ops *ops);
 
 struct net *rtnl_link_get_net(struct net *src_net, struct nlattr *tb[]);

net/bridge/br_netlink.c

@@ -1924,7 +1924,9 @@ int __init br_netlink_init(void)
 	if (err)
 		goto out;
 
-	rtnl_af_register(&br_af_ops);
+	err = rtnl_af_register(&br_af_ops);
+	if (err)
+		goto out_vlan;
 
 	err = rtnl_link_register(&br_link_ops);
 	if (err)
@@ -1934,6 +1936,8 @@ int __init br_netlink_init(void)
 
 out_af:
 	rtnl_af_unregister(&br_af_ops);
+out_vlan:
+	br_vlan_rtnl_uninit();
 out:
 	return err;
 }