[NET]: Make lapbether work on 2.6.0-test3.

- unneeded include (no proc here)
- redundant fields in local device structure
+ convert to dynamic network device allocation
- refcounts on local data are redundant, it is really part of network_device
- excessive __inline__
+ correctly manage references to underlying network device
+ cascade unregister
+ use RCU and RTNL to avoid deadlock
+ account for bytes as well as packets

drivers/net/wan/lapbether.c

@@ -37,7 +37,6 @@
 #include <linux/mm.h>
 #include <linux/interrupt.h>
 #include <linux/notifier.h>
-#include <linux/proc_fs.h>
 #include <linux/stat.h>
 #include <linux/netfilter.h>
 #include <linux/module.h>
@@ -52,50 +51,27 @@ static char bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
 
 struct lapbethdev {
 	struct list_head	node;
-	char			ethname[14];	/* ether device name */
 	struct net_device	*ethdev;	/* link to ethernet device */
-	struct net_device	axdev;		/* lapbeth device (lapb#) */
+	struct net_device	*axdev;		/* lapbeth device (lapb#) */
 	struct net_device_stats stats;		/* some statistics */
-	atomic_t		refcnt;
 };
 
 static struct list_head lapbeth_devices = LIST_HEAD_INIT(lapbeth_devices);
-static rwlock_t lapbeth_devices_lock = RW_LOCK_UNLOCKED;
 
-static __inline__ void lapbeth_hold(struct lapbethdev *lapbeth)
-{
-	atomic_inc(&lapbeth->refcnt);
-}
-
-static __inline__ void lapbeth_put(struct lapbethdev *lapbeth)
-{
-	if (atomic_dec_and_test(&lapbeth->refcnt))
-		kfree(lapbeth);
-}
 /* ------------------------------------------------------------------------ */
 
 /*
  *	Get the LAPB device for the ethernet device
  */
-static __inline__ struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
+static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
 {
-	struct list_head *entry;
-	struct lapbethdev *lapbeth, *use = NULL;
-
-	read_lock(&lapbeth_devices_lock);
+	struct lapbethdev *lapbeth;
 
-	list_for_each(entry, &lapbeth_devices) {
-		lapbeth = list_entry(entry, struct lapbethdev, node);
-		if (lapbeth->ethdev == dev) {
-			use = lapbeth;
-			break;
-		}
+	list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node) {
+		if (lapbeth->ethdev == dev) 
+			return lapbeth;
 	}
-	if (use)
-		lapbeth_hold(use);
-
-	read_unlock(&lapbeth_devices_lock);
-	return use;
+	return NULL;
 }
 
 static __inline__ int dev_is_ethdev(struct net_device *dev)
@@ -103,36 +79,6 @@ static __inline__ int dev_is_ethdev(struct net_device *dev)
 	return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
 }
 
-/*
- *	Sanity check: remove all devices that ceased to exists and
- *	return '1' if the given LAPB device was affected.
- */
-static int lapbeth_check_devices(struct net_device *dev)
-{
-	struct lapbethdev *lapbeth;
-	struct list_head *entry, *tmp;
-	int result = 0;
-
-	write_lock(&lapbeth_devices_lock);
-
-	list_for_each_safe(entry, tmp, &lapbeth_devices) {
-		lapbeth = list_entry(entry, struct lapbethdev, node);
-
-		if (!dev_get(lapbeth->ethname)) {
-			if (&lapbeth->axdev == dev)
-				result = 1;
-
-			unregister_netdev(&lapbeth->axdev);
-			dev_put(lapbeth->ethdev);
-			list_del(&lapbeth->node);
-			lapbeth_put(lapbeth);
-		}
-	}
-	write_unlock(&lapbeth_devices_lock);
-
-	return result;
-}
-
 /* ------------------------------------------------------------------------ */
 
 /*
@@ -145,29 +91,28 @@ static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packe
 
 	skb->sk = NULL;		/* Initially we don't know who it's for */
 
+	rcu_read_lock();
 	lapbeth = lapbeth_get_x25_dev(dev);
-
 	if (!lapbeth)
 		goto drop;
-	if (!netif_running(&lapbeth->axdev))
-		goto put_drop;
+	if (!netif_running(lapbeth->axdev))
+		goto drop;
 
 	lapbeth->stats.rx_packets++;
 
 	len = skb->data[0] + skb->data[1] * 256;
+	lapbeth->stats.rx_bytes += len;
 
 	skb_pull(skb, 2);	/* Remove the length bytes */
 	skb_trim(skb, len);	/* Set the length of the data */
 
 	if ((err = lapb_data_received(lapbeth, skb)) != LAPB_OK) {
 		printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
-		goto put_drop;
+		goto drop;
 	}
-	lapbeth_put(lapbeth);
 out:
+	rcu_read_unlock();
 	return 0;
-put_drop:
-	lapbeth_put(lapbeth);
 drop:
 	kfree_skb(skb);
 	goto out;
@@ -181,7 +126,7 @@ static int lapbeth_data_indication(void *token, struct sk_buff *skb)
 	ptr  = skb_push(skb, 1);
 	*ptr = 0x00;
 
-	skb->dev      = &lapbeth->axdev;
+	skb->dev      = lapbeth->axdev;
 	skb->protocol = htons(ETH_P_X25);
 	skb->mac.raw  = skb->data;
 	skb->pkt_type = PACKET_HOST;
@@ -203,7 +148,6 @@ static int lapbeth_xmit(struct sk_buff *skb, struct net_device *dev)
 	 * is down, the ethernet device may have gone.
 	 */
 	if (!netif_running(dev)) {
-		lapbeth_check_devices(dev);
 		goto drop;
 	}
 
@@ -257,6 +201,7 @@ static void lapbeth_data_transmit(void *token, struct sk_buff *skb)
 	*ptr++ = size / 256;
 
 	lapbeth->stats.tx_packets++;
+	lapbeth->stats.tx_bytes += size;
 
 	skb->dev = dev = lapbeth->ethdev;
 
@@ -279,7 +224,7 @@ static void lapbeth_connected(void *token, int reason)
 	ptr  = skb_put(skb, 1);
 	*ptr = 0x01;
 
-	skb->dev      = &lapbeth->axdev;
+	skb->dev      = lapbeth->axdev;
 	skb->protocol = htons(ETH_P_X25);
 	skb->mac.raw  = skb->data;
 	skb->pkt_type = PACKET_HOST;
@@ -302,7 +247,7 @@ static void lapbeth_disconnected(void *token, int reason)
 	ptr  = skb_put(skb, 1);
 	*ptr = 0x02;
 
-	skb->dev      = &lapbeth->axdev;
+	skb->dev      = lapbeth->axdev;
 	skb->protocol = htons(ETH_P_X25);
 	skb->mac.raw  = skb->data;
 	skb->pkt_type = PACKET_HOST;
@@ -330,27 +275,26 @@ static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
 	return 0;
 }
 
+
+static struct lapb_register_struct lapbeth_callbacks = {
+	.connect_confirmation    = lapbeth_connected,
+	.connect_indication      = lapbeth_connected,
+	.disconnect_confirmation = lapbeth_disconnected,
+	.disconnect_indication   = lapbeth_disconnected,
+	.data_indication         = lapbeth_data_indication,
+	.data_transmit           = lapbeth_data_transmit,
+
+};
+
 /*
  * open/close a device
  */
 static int lapbeth_open(struct net_device *dev)
 {
-	struct lapb_register_struct lapbeth_callbacks;
 	struct lapbethdev *lapbeth;
 	int err;
 
-	if (lapbeth_check_devices(dev))
-		return -ENODEV;		/* oops, it's gone */
-
 	lapbeth = (struct lapbethdev *)dev->priv;
-
-	lapbeth_callbacks.connect_confirmation    = lapbeth_connected;
-	lapbeth_callbacks.connect_indication      = lapbeth_connected;
-	lapbeth_callbacks.disconnect_confirmation = lapbeth_disconnected;
-	lapbeth_callbacks.disconnect_indication   = lapbeth_disconnected;
-	lapbeth_callbacks.data_indication         = lapbeth_data_indication;
-	lapbeth_callbacks.data_transmit           = lapbeth_data_transmit;
-
 	if ((err = lapb_register(lapbeth, &lapbeth_callbacks)) != LAPB_OK) {
 		printk(KERN_ERR "lapbeth: lapb_register error - %d\n", err);
 		return -ENODEV;
@@ -375,65 +319,52 @@ static int lapbeth_close(struct net_device *dev)
 
 /* ------------------------------------------------------------------------ */
 
+static void lapbeth_setup(struct net_device *dev)
+{
+	dev->hard_start_xmit = lapbeth_xmit;
+	dev->open	     = lapbeth_open;
+	dev->stop	     = lapbeth_close;
+	dev->destructor	     = (void (*)(struct net_device *))kfree;
+	dev->set_mac_address = lapbeth_set_mac_address;
+	dev->get_stats	     = lapbeth_get_stats;
+	dev->type            = ARPHRD_X25;
+	dev->hard_header_len = 3;
+	dev->mtu             = 1000;
+	dev->addr_len        = 0;
+	SET_MODULE_OWNER(dev);
+}
+
 /*
  *	Setup a new device.
  */
 static int lapbeth_new_device(struct net_device *dev)
 {
-	unsigned char buf[14];
+	struct net_device *ndev;
 	struct lapbethdev *lapbeth;
-	int k, rc = -ENOMEM;
+	int rc = -ENOMEM;
 
-	if ((lapbeth = kmalloc(sizeof(struct lapbethdev), GFP_ATOMIC)) == NULL)
+	ASSERT_RTNL();
+
+	ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", 
+			   lapbeth_setup);
+	if (!ndev)
 		goto out;
 
-	memset(lapbeth, 0, sizeof(struct lapbethdev));
+	lapbeth = ndev->priv;
+	lapbeth->axdev = ndev;
 
 	dev_hold(dev);
 	lapbeth->ethdev = dev;
 
-	strncpy(lapbeth->ethname, dev->name, sizeof(lapbeth->ethname) - 1);
-	lapbeth->ethname[sizeof(lapbeth->ethname) - 1] = '\0';
-	atomic_set(&lapbeth->refcnt, 1);
-
-	dev = &lapbeth->axdev;
-	SET_MODULE_OWNER(dev);
-
-	for (k = 0; k < MAXLAPBDEV; k++) {
-		struct net_device *odev;
-
-		sprintf(buf, "lapb%d", k);
-
-		if ((odev = __dev_get_by_name(buf)) == NULL ||
-		    lapbeth_check_devices(odev))
-			break;
-	}
-
-	rc = -ENODEV;
-	if (k == MAXLAPBDEV)
+	rc = dev_alloc_name(ndev, ndev->name);
+	if (rc < 0) 
 		goto fail;
 
-	dev->priv = (void *)lapbeth;	/* pointer back */
-	strcpy(dev->name, buf);
-
 	rc = -EIO;
-	if (register_netdev(dev))
+	if (register_netdevice(ndev))
 		goto fail;
 
-	dev->hard_start_xmit = lapbeth_xmit;
-	dev->open	     = lapbeth_open;
-	dev->stop	     = lapbeth_close;
-	dev->set_mac_address = lapbeth_set_mac_address;
-	dev->get_stats	     = lapbeth_get_stats;
-	dev->type            = ARPHRD_X25;
-	dev->hard_header_len = 3;
-	dev->mtu             = 1000;
-	dev->addr_len        = 0;
-
-	write_lock(&lapbeth_devices_lock);
-	list_add(&lapbeth->node, &lapbeth_devices);
-	lapbeth_hold(lapbeth);
-	write_unlock(&lapbeth_devices_lock);
+	list_add_rcu(&lapbeth->node, &lapbeth_devices);
 	rc = 0;
 out:
 	return rc;
@@ -443,6 +374,16 @@ static int lapbeth_new_device(struct net_device *dev)
 	goto out;
 }
 
+/*
+ *	Free a lapb network device.
+ */
+static void lapbeth_free_device(struct lapbethdev *lapbeth)
+{
+	dev_put(lapbeth->ethdev);
+	list_del_rcu(&lapbeth->node);
+	unregister_netdevice(lapbeth->axdev);
+}
+
 /*
  *	Handle device status changes.
  */
@@ -455,30 +396,27 @@ static int lapbeth_device_event(struct notifier_block *this,
 	if (!dev_is_ethdev(dev))
 		return NOTIFY_DONE;
 
-	lapbeth_check_devices(NULL);
-
+	rcu_read_lock();
 	switch (event) {
 	case NETDEV_UP:
-		/*
-		 * New ethernet device -> new LAPB interface
-		 */
-		lapbeth = lapbeth_get_x25_dev(dev);
-
-		if (lapbeth)
-			lapbeth_put(lapbeth);
-		else
+		/* New ethernet device -> new LAPB interface	 */
+		if (lapbeth_get_x25_dev(dev) == NULL)
 			lapbeth_new_device(dev);
 		break;
-	case NETDEV_GOING_DOWN:
-	case NETDEV_DOWN:	/* ethernet device closed -> close LAPB interface */
+	case NETDEV_DOWN:	
+		/* ethernet device closed -> close LAPB interface */
 		lapbeth = lapbeth_get_x25_dev(dev);
-
-		if (lapbeth) {
-			dev_close(lapbeth->ethdev);
-			lapbeth_put(lapbeth);
-		}
+		if (lapbeth) 
+			dev_close(lapbeth->axdev);
+		break;
+	case NETDEV_UNREGISTER:
+		/* ethernet device disappears -> remove LAPB interface */
+		lapbeth = lapbeth_get_x25_dev(dev);
+		if (lapbeth)
+			lapbeth_free_device(lapbeth);
 		break;
 	}
+	rcu_read_unlock();
 
 	return NOTIFY_DONE;
 }
@@ -506,15 +444,13 @@ static int __init lapbeth_init_driver(void)
 
 	printk(banner);
 
-	read_lock_bh(&dev_base_lock);
+	rtnl_lock();
 	for (dev = dev_base; dev; dev = dev->next) {
 		if (dev_is_ethdev(dev)) {
-			read_unlock_bh(&dev_base_lock);
 			lapbeth_new_device(dev);
-			read_lock_bh(&dev_base_lock);
 		}
 	}
-	read_unlock_bh(&dev_base_lock);
+	rtnl_unlock();
 
 	return 0;
 }
@@ -528,16 +464,13 @@ static void __exit lapbeth_cleanup_driver(void)
 	dev_remove_pack(&lapbeth_packet_type);
 	unregister_netdevice_notifier(&lapbeth_dev_notifier);
 
-	write_lock(&lapbeth_devices_lock);
-
+	rtnl_lock();
 	list_for_each_safe(entry, tmp, &lapbeth_devices) {
 		lapbeth = list_entry(entry, struct lapbethdev, node);
-		unregister_netdev(&lapbeth->axdev);
-		list_del(&lapbeth->node);
-		lapbeth_put(lapbeth);
-	}
 
-	write_unlock(&lapbeth_devices_lock);
+		unregister_netdevice(lapbeth->axdev);
+	}
+	rtnl_unlock();
 }
 module_exit(lapbeth_cleanup_driver);