[NETNS]: Move some code into __init section when CONFIG_NET_NS=n

With the net namespaces many code leaved the __init section,
thus making the kernel occupy more memory than it did before.
Since we have a config option that prohibits the namespace
creation, the functions that initialize/finalize some netns
stuff are simply not needed and can be freed after the boot.

Currently, this is almost not noticeable, since few calls
are no longer in __init, but when the namespaces will be
merged it will be possible to free more code. I propose to
use the __net_init, __net_exit and __net_initdata "attributes"
for functions/variables that are not used if the CONFIG_NET_NS
is not set to save more space in memory.

The exiting functions cannot just reside in the __exit section,
as noticed by David, since the init section will have
references on it and the compilation will fail due to modpost
checks. These references can exist, since the init namespace
never dies and the exit callbacks are never called. So I
introduce the __exit_refok attribute just like it is already
done with the __init_refok.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index d6997aec45d..be25aa33971 100644
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -250,7 +250,7 @@ static void loopback_setup(struct net_device *dev)
 }
 
 /* Setup and register the loopback device. */
-static int loopback_net_init(struct net *net)
+static __net_init int loopback_net_init(struct net *net)
 {
         struct net_device *dev;
         int err;
@@ -278,14 +278,14 @@ out_free_netdev:
         goto out;
 }
 
-static void loopback_net_exit(struct net *net)
+static __net_exit void loopback_net_exit(struct net *net)
 {
         struct net_device *dev = net->loopback_dev;
 
         unregister_netdev(dev);
 }
 
-static struct pernet_operations loopback_net_ops = {
+static struct pernet_operations __net_initdata loopback_net_ops = {
        .init = loopback_net_init,
        .exit = loopback_net_exit,
 };