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, 9 insertions, 9 deletions

diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c
index 9478d9b3d977..d936226916f2 100644
--- a/net/rose/rose_route.c
+++ b/net/rose/rose_route.c
@@ -600,13 +600,13 @@ struct net_device *rose_dev_first(void)
 {
         struct net_device *dev, *first = NULL;
 
-        read_lock(&dev_base_lock);
-        for_each_netdev(&init_net, dev) {
+        rcu_read_lock();
+        for_each_netdev_rcu(&init_net, dev) {
                 if ((dev->flags & IFF_UP) && dev->type == ARPHRD_ROSE)
                         if (first == NULL || strncmp(dev->name, first->name, 3) < 0)
                                 first = dev;
         }
-        read_unlock(&dev_base_lock);
+        rcu_read_unlock();
 
         return first;
 }
@@ -618,8 +618,8 @@ struct net_device *rose_dev_get(rose_address *addr)
 {
         struct net_device *dev;
 
-        read_lock(&dev_base_lock);
-        for_each_netdev(&init_net, dev) {
+        rcu_read_lock();
+        for_each_netdev_rcu(&init_net, dev) {
                 if ((dev->flags & IFF_UP) && dev->type == ARPHRD_ROSE && rosecmp(addr, (rose_address *)dev->dev_addr) == 0) {
                         dev_hold(dev);
                         goto out;
@@ -627,7 +627,7 @@ struct net_device *rose_dev_get(rose_address *addr)
         }
         dev = NULL;
 out:
-        read_unlock(&dev_base_lock);
+        rcu_read_unlock();
         return dev;
 }
 
@@ -635,14 +635,14 @@ static int rose_dev_exists(rose_address *addr)
 {
         struct net_device *dev;
 
-        read_lock(&dev_base_lock);
-        for_each_netdev(&init_net, dev) {
+        rcu_read_lock();
+        for_each_netdev_rcu(&init_net, dev) {
                 if ((dev->flags & IFF_UP) && dev->type == ARPHRD_ROSE && rosecmp(addr, (rose_address *)dev->dev_addr) == 0)
                         goto out;
         }
         dev = NULL;
 out:
-        read_unlock(&dev_base_lock);
+        rcu_read_unlock();
         return dev != NULL;
 }