Merge branch 'Rework-ip_ra_chain-protection'

Kirill Tkhai says:

====================
Rework ip_ra_chain protection

Commit 1215e51edad1 "ipv4: fix a deadlock in ip_ra_control"
made rtnl_lock() be used in raw_close(). This function is called
on every RAW socket destruction, so that rtnl_mutex is taken
every time. This scales very sadly. I observe cleanup_net()
spending a lot of time in rtnl_lock() and raw_close() is one
of the biggest rtnl user (since we have percpu net->ipv4.icmp_sk).

This patchset reworks the locking: reverts the problem commit
and its descendant, and introduces rtnl-independent locking.
This may have a continuation, and someone may work on killing
rtnl_lock() in mrtsock_destruct() in the future.

v3: Change patches order: [2/5] and [3/5].
v2: Fix sparse warning [4/5], as reported by kbuild test robot.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 13 insertions, 2 deletions

diff --git a/include/net/ip.h b/include/net/ip.h
index fe63ba95d12b..d53b5a9eae34 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -91,6 +91,17 @@ static inline int inet_sdif(struct sk_buff *skb)
 	return 0;
 }
 
+/* Special input handler for packets caught by router alert option.
+   They are selected only by protocol field, and then processed likely
+   local ones; but only if someone wants them! Otherwise, router
+   not running rsvpd will kill RSVP.
+
+   It is user level problem, what it will make with them.
+   I have no idea, how it will masquearde or NAT them (it is joke, joke :-)),
+   but receiver should be enough clever f.e. to forward mtrace requests,
+   sent to multicast group to reach destination designated router.
+ */
+
 struct ip_ra_chain {
 	struct ip_ra_chain __rcu *next;
 	struct sock		*sk;
@@ -101,8 +112,6 @@ struct ip_ra_chain {
 	struct rcu_head		rcu;
 };
 
-extern struct ip_ra_chain __rcu *ip_ra_chain;
-
 /* IP flags. */
 #define IP_CE		0x8000		/* Flag: "Congestion"		*/
 #define IP_DF		0x4000		/* Flag: "Don't Fragment"	*/
diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 382bfd7583cf..8491bc9c86b1 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -49,6 +49,8 @@ struct netns_ipv4 {
 #endif
 	struct ipv4_devconf	*devconf_all;
 	struct ipv4_devconf	*devconf_dflt;
+	struct ip_ra_chain __rcu *ra_chain;
+	struct mutex		ra_mutex;
 #ifdef CONFIG_IP_MULTIPLE_TABLES
 	struct fib_rules_ops	*rules_ops;
 	bool			fib_has_custom_rules;