net: Add init_dummy_netdev() and fix EMAC driver using it

This adds an init_dummy_netdev() function that gets a network device
structure (allocation and lifetime entirely under caller's control) and
initialize the minimum amount of fields so it can be used to schedule
NAPI polls without registering a full blown interface. This is to be
used by drivers that need to tie several hardware interfaces to a single
NAPI poll scheduler due to HW limitations.

It also updates the ibm_newemac driver to use that, this fixing the
oops on 2.6.29 due to passing NULL as "dev" to netif_napi_add()

Symbol is exported GPL only a I don't think we want binary drivers doing
that sort of acrobatics (if we want them at all).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Tested-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 4647604c7ca9..ec54785d34f9 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -795,6 +795,7 @@ struct net_device
                NETREG_UNREGISTERING,    /* called unregister_netdevice */
                NETREG_UNREGISTERED,     /* completed unregister todo */
                NETREG_RELEASED,         /* called free_netdev */
+               NETREG_DUMMY,            /* dummy device for NAPI poll */
         } reg_state;
 
         /* Called from unregister, can be used to call free_netdev */
@@ -1077,6 +1078,8 @@ extern void		free_netdev(struct net_device *dev);
 extern void             synchronize_net(void);
 extern int              register_netdevice_notifier(struct notifier_block *nb);
 extern int              unregister_netdevice_notifier(struct notifier_block *nb);
+extern int              init_dummy_netdev(struct net_device *dev);
+
 extern int call_netdevice_notifiers(unsigned long val, struct net_device *dev);
 extern struct net_device        *dev_get_by_index(struct net *net, int ifindex);
 extern struct net_device        *__dev_get_by_index(struct net *net, int ifindex);