rps: add __rcu annotations

Add __rcu annotations to :
	(struct netdev_rx_queue)->rps_map
	(struct netdev_rx_queue)->rps_flow_table
	struct rps_sock_flow_table *rps_sock_flow_table;

And use appropriate rcu primitives.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 01eee5d..385b609 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -34,7 +34,8 @@
 
 	mutex_lock(&sock_flow_mutex);
 
-	orig_sock_table = rps_sock_flow_table;
+	orig_sock_table = rcu_dereference_protected(rps_sock_flow_table,
+					lockdep_is_held(&sock_flow_mutex));
 	size = orig_size = orig_sock_table ? orig_sock_table->mask + 1 : 0;
 
 	ret = proc_dointvec(&tmp, write, buffer, lenp, ppos);