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>

3 files changed, 9 insertions, 9 deletions

diff --git a/net/decnet/af_decnet.c b/net/decnet/af_decnet.c
index 664965c87e16..2e355841ca99 100644
--- a/net/decnet/af_decnet.c
+++ b/net/decnet/af_decnet.c
@@ -749,9 +749,9 @@ static int dn_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 
         if (!(saddr->sdn_flags & SDF_WILD)) {
                 if (le16_to_cpu(saddr->sdn_nodeaddrl)) {
-                        read_lock(&dev_base_lock);
+                        rcu_read_lock();
                         ldev = NULL;
-                        for_each_netdev(&init_net, dev) {
+                        for_each_netdev_rcu(&init_net, dev) {
                                 if (!dev->dn_ptr)
                                         continue;
                                 if (dn_dev_islocal(dev, dn_saddr2dn(saddr))) {
@@ -759,7 +759,7 @@ static int dn_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
                                         break;
                                 }
                         }
-                        read_unlock(&dev_base_lock);
+                        rcu_read_unlock();
                         if (ldev == NULL)
                                 return -EADDRNOTAVAIL;
                 }
diff --git a/net/decnet/dn_fib.c b/net/decnet/dn_fib.c
index 27ea2e9b080a..fd641f65e092 100644
--- a/net/decnet/dn_fib.c
+++ b/net/decnet/dn_fib.c
@@ -607,8 +607,8 @@ static void dn_fib_del_ifaddr(struct dn_ifaddr *ifa)
         ASSERT_RTNL();
 
         /* Scan device list */
-        read_lock(&dev_base_lock);
-        for_each_netdev(&init_net, dev) {
+        rcu_read_lock();
+        for_each_netdev_rcu(&init_net, dev) {
                 dn_db = dev->dn_ptr;
                 if (dn_db == NULL)
                         continue;
@@ -619,7 +619,7 @@ static void dn_fib_del_ifaddr(struct dn_ifaddr *ifa)
                         }
                 }
         }
-        read_unlock(&dev_base_lock);
+        rcu_read_unlock();
 
         if (found_it == 0) {
                 fib_magic(RTM_DELROUTE, RTN_LOCAL, ifa->ifa_local, 16, ifa);
diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index 57662cabaf9b..860286a3921b 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -908,8 +908,8 @@ static int dn_route_output_slow(struct dst_entry **pprt, const struct flowi *old
                         dev_put(dev_out);
                         goto out;
                 }
-                read_lock(&dev_base_lock);
-                for_each_netdev(&init_net, dev) {
+                rcu_read_lock();
+                for_each_netdev_rcu(&init_net, dev) {
                         if (!dev->dn_ptr)
                                 continue;
                         if (!dn_dev_islocal(dev, oldflp->fld_src))
@@ -922,7 +922,7 @@ static int dn_route_output_slow(struct dst_entry **pprt, const struct flowi *old
                         dev_out = dev;
                         break;
                 }
-                read_unlock(&dev_base_lock);
+                rcu_read_unlock();
                 if (dev_out == NULL)
                         goto out;
                 dev_hold(dev_out);