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 <b...@kernel.crashing.org>
---
Index: linux-work/include/linux/netdevice.h
===================================================================
--- linux-work.orig/include/linux/netdevice.h 2009-01-13 16:13:41.000000000
+1100
+++ linux-work/include/linux/netdevice.h 2009-01-14 14:13:24.000000000
+1100
@@ -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_devi
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);
Index: linux-work/net/core/dev.c
===================================================================
--- linux-work.orig/net/core/dev.c 2009-01-13 16:17:52.000000000 +1100
+++ linux-work/net/core/dev.c 2009-01-14 14:24:03.000000000 +1100
@@ -4434,6 +4434,45 @@ err_uninit:
}
/**
+ * init_dummy_netdev - init a dummy network device for NAPI
+ * @dev: device to init
+ *
+ * This takes a network device structure 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.
+ */
+int init_dummy_netdev(struct net_device *dev)
+{
+ /* Clear everything. Note we don't initialize spinlocks
+ * are they aren't supposed to be taken by any of the
+ * NAPI code and this dummy netdev is supposed to be
+ * only ever used for NAPI polls
+ */
+ memset(dev, 0, sizeof(struct net_device));
+
+ /* make sure we BUG if trying to hit standard
+ * register/unregister code path
+ */
+ dev->reg_state = NETREG_DUMMY;
+
+ /* initialize the ref count */
+ atomic_set(&dev->refcnt, 1);
+
+ /* NAPI wants this */
+ INIT_LIST_HEAD(&dev->napi_list);
+
+ /* a dummy interface is started by default */
+ set_bit(__LINK_STATE_PRESENT, &dev->state);
+ set_bit(__LINK_STATE_START, &dev->state);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(init_dummy_netdev);
+
+
+/**
* register_netdev - register a network device
* @dev: device to register
*
Index: linux-work/drivers/net/ibm_newemac/mal.c
===================================================================
--- linux-work.orig/drivers/net/ibm_newemac/mal.c 2009-01-14
14:25:10.000000000 +1100
+++ linux-work/drivers/net/ibm_newemac/mal.c 2009-01-14 14:25:30.000000000
+1100
@@ -613,7 +613,9 @@ static int __devinit mal_probe(struct of
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 */
Index: linux-work/drivers/net/ibm_newemac/mal.h
===================================================================
--- linux-work.orig/drivers/net/ibm_newemac/mal.h 2009-01-14
14:24:40.000000000 +1100
+++ linux-work/drivers/net/ibm_newemac/mal.h 2009-01-14 14:24:58.000000000
+1100
@@ -214,6 +214,8 @@ struct mal_instance {
int index;
spinlock_t lock;
+ struct net_device dummy_dev;
+
unsigned int features;
};
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