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>

2 files changed, 5 insertions, 1 deletions

diff --git a/drivers/net/ibm_newemac/mal.c b/drivers/net/ibm_newemac/mal.c
index ecf9798987fa..2a2fc17b2878 100644
--- a/drivers/net/ibm_newemac/mal.c
+++ b/drivers/net/ibm_newemac/mal.c
@@ -613,7 +613,9 @@ static int __devinit mal_probe(struct of_device *ofdev,
         INIT_LIST_HEAD(&mal->list);
         spin_lock_init(&mal->lock);
 
-        netif_napi_add(NULL, &mal->napi, mal_poll,
+        init_dummy_netdev(&mal->dummy_dev);
+
+        netif_napi_add(&mal->dummy_dev, &mal->napi, mal_poll,
                        CONFIG_IBM_NEW_EMAC_POLL_WEIGHT);
 
         /* Load power-on reset defaults */
diff --git a/drivers/net/ibm_newemac/mal.h b/drivers/net/ibm_newemac/mal.h
index 2f0a87360844..9ededfbf0726 100644
--- a/drivers/net/ibm_newemac/mal.h
+++ b/drivers/net/ibm_newemac/mal.h
@@ -214,6 +214,8 @@ struct mal_instance {
         int                     index;
         spinlock_t              lock;
 
+        struct net_device       dummy_dev;
+
         unsigned int features;
 };