net: Introduce for_each_netdev_rcu() iterator

Adds RCU management to the list of netdevices.

Convert some for_each_netdev() users to RCU version, if
it can avoid read_lock-ing dev_base_lock

Ie:
	read_lock(&dev_base_loack);
	for_each_netdev(net, dev)
		some_action();
	read_unlock(&dev_base_lock);

becomes :

	rcu_read_lock();
	for_each_netdev_rcu(net, dev)
		some_action();
	rcu_read_unlock();


Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 3 deletions

diff --git a/net/ipv6/anycast.c b/net/ipv6/anycast.c
index 1ae58bec1de0..2f00ca83f049 100644
--- a/net/ipv6/anycast.c
+++ b/net/ipv6/anycast.c
@@ -404,13 +404,13 @@ int ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
 
         if (dev)
                 return ipv6_chk_acast_dev(dev, addr);
-        read_lock(&dev_base_lock);
-        for_each_netdev(net, dev)
+        rcu_read_lock();
+        for_each_netdev_rcu(net, dev)
                 if (ipv6_chk_acast_dev(dev, addr)) {
                         found = 1;
                         break;
                 }
-        read_unlock(&dev_base_lock);
+        rcu_read_unlock();
         return found;
 }