net_kern.c

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/*
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Copyright (C) 2001 Lennert Buytenhek ([e-mail]) and
 * James Leu ([e-mail]).
 * Copyright (C) 2001 by various other people who didn't put their name here.
 * Licensed under the GPL.
 */

#include <linux/bootmem.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/inetdevice.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/netdevice.h>
#include <linux/platform_device.h>
#include <linux/rtnetlink.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include "init.h"
#include "irq_kern.h"
#include "irq_user.h"
#include "mconsole_kern.h"
#include "net_kern.h"
#include "net_user.h"

static inline void set_ether_mac(struct net_device *dev, unsigned char *addr)
{
	memcpy(dev->dev_addr, addr, ETH_ALEN);
}

#define DRIVER_NAME "uml-netdev"

static DEFINE_SPINLOCK(opened_lock);
static LIST_HEAD(opened);

/*
 * The drop_skb is used when we can't allocate an skb.  The
 * packet is read into drop_skb in order to get the data off the
 * connection to the host.
 * It is reallocated whenever a maximum packet size is seen which is
 * larger than any seen before.  update_drop_skb is called from
 * eth_configure when a new interface is added.
 */
static DEFINE_SPINLOCK(drop_lock);
static struct sk_buff *drop_skb;
static int drop_max;

static int update_drop_skb(int max)
{
	struct sk_buff *new;
	unsigned long flags;
	int err = 0;

	spin_lock_irqsave(&drop_lock, flags);

	if (max <= drop_max)
		goto out;

	err = -ENOMEM;
	new = dev_alloc_skb(max);
	if (new == NULL)
		goto out;

	skb_put(new, max);

	kfree_skb(drop_skb);
	drop_skb = new;
	drop_max = max;
	err = 0;
out:
	spin_unlock_irqrestore(&drop_lock, flags);

	return err;
}

static int uml_net_rx(struct net_device *dev)
{
	struct uml_net_private *lp = dev->priv;
	int pkt_len;
	struct sk_buff *skb;

	/* If we can't allocate memory, try again next round. */
	skb = dev_alloc_skb(lp->max_packet);
	if (skb == NULL) {
		drop_skb->dev = dev;
		/* Read a packet into drop_skb and don't do anything with it. */
		(*lp->read)(lp->fd, drop_skb, lp);
		lp->stats.rx_dropped++;
		return 0;
	}

	skb->dev = dev;
	skb_put(skb, lp->max_packet);
	skb_reset_mac_header(skb);
	pkt_len = (*lp->read)(lp->fd, skb, lp);

	if (pkt_len > 0) {
		skb_trim(skb, pkt_len);
		skb->protocol = (*lp->protocol)(skb);

		lp->stats.rx_bytes += skb->len;
		lp->stats.rx_packets++;
		netif_rx(skb);
		return pkt_len;
	}

	kfree_skb(skb);
	return pkt_len;
}

static void uml_dev_close(struct work_struct *work)
{
	struct uml_net_private *lp =
		container_of(work, struct uml_net_private, work);
	dev_close(lp->dev);
}

irqreturn_t uml_net_interrupt(int irq, void *dev_id)
{
	struct net_device *dev = dev_id;
	struct uml_net_private *lp = dev->priv;
	int err;

	if (!netif_running(dev))
		return IRQ_NONE;

	spin_lock(&lp->lock);
	while ((err = uml_net_rx(dev)) > 0) ;
	if (err < 0) {
		printk(KERN_ERR
		       "Device '%s' read returned %d, shutting it down\n",
		       dev->name, err);
		/* dev_close can't be called in interrupt context, and takes
		 * again lp->lock.
		 * And dev_close() can be safely called multiple times on the
		 * same device, since it tests for (dev->flags & IFF_UP). So
		 * there's no harm in delaying the device shutdown.
		 * Furthermore, the workqueue will not re-enqueue an already
		 * enqueued work item. */
		schedule_work(&lp->work);
		goto out;
	}
	reactivate_fd(lp->fd, UM_ETH_IRQ);

out:
	spin_unlock(&lp->lock);
	return IRQ_HANDLED;
}

static int uml_net_open(struct net_device *dev)
{
	struct uml_net_private *lp = dev->priv;
	int err;

	if (lp->fd >= 0) {
		err = -ENXIO;
		goto out;
	}

	lp->fd = (*lp->open)(&lp->user);
	if (lp->fd < 0) {
		err = lp->fd;
		goto out;
	}

	err = um_request_irq(dev->irq, lp->fd, IRQ_READ, uml_net_interrupt,
			     IRQF_DISABLED | IRQF_SHARED, dev->name, dev);
	if (err != 0) {
		printk(KERN_ERR "uml_net_open: failed to get irq(%d)\n", err);
		err = -ENETUNREACH;
		goto out_close;
	}

	lp->tl.data = (unsigned long) &lp->user;
	netif_start_queue(dev);

	/* clear buffer - it can happen that the host side of the interface
	 * is full when we get here.  In this case, new data is never queued,
	 * SIGIOs never arrive, and the net never works.
	 */
	while ((err = uml_net_rx(dev)) > 0) ;

	spin_lock(&opened_lock);
	list_add(&lp->list, &opened);
	spin_unlock(&opened_lock);

	return 0;
out_close:
	if (lp->close != NULL) (*lp->close)(lp->fd, &lp->user);
	lp->fd = -1;
out:
	return err;
}

static int uml_net_close(struct net_device *dev)
{
	struct uml_net_private *lp = dev->priv;

	netif_stop_queue(dev);

	free_irq(dev->irq, dev);
	if (lp->close != NULL)
		(*lp->close)(lp->fd, &lp->user);
	lp->fd = -1;

	spin_lock(&opened_lock);
	list_del(&lp->list);
	spin_unlock(&opened_lock);

	return 0;
}

static int uml_net_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct uml_net_private *lp = dev->priv;
	unsigned long flags;
	int len;

	netif_stop_queue(dev);

	spin_lock_irqsave(&lp->lock, flags);

	len = (*lp->write)(lp->fd, skb, lp);

	if (len == skb->len) {
		lp->stats.tx_packets++;
		lp->stats.tx_bytes += skb->len;
		dev->trans_start = jiffies;
		netif_start_queue(dev);

		/* this is normally done in the interrupt when tx finishes */
		netif_wake_queue(dev);
	}
	else if (len == 0) {
		netif_start_queue(dev);
		lp->stats.tx_dropped++;
	}
	else {
		netif_start_queue(dev);
		printk(KERN_ERR "uml_net_start_xmit: failed(%d)\n", len);
	}

	spin_unlock_irqrestore(&lp->lock, flags);

	dev_kfree_skb(skb);

	return 0;
}

static struct net_device_stats *uml_net_get_stats(struct net_device *dev)
{
	struct uml_net_private *lp = dev->priv;
	return &lp->stats;
}

static void uml_net_set_multicast_list(struct net_device *dev)
{
	if (dev->flags & IFF_PROMISC)
		return;
	else if (dev->mc_count)
		dev->flags |= IFF_ALLMULTI;
	else dev->flags &= ~IFF_ALLMULTI;
}

static void uml_net_tx_timeout(struct net_device *dev)
{
	dev->trans_start = jiffies;
	netif_wake_queue(dev);
}

static int uml_net_set_mac(struct net_device *dev, void *addr)
{
	struct uml_net_private *lp = dev->priv;
	struct sockaddr *hwaddr = addr;

	spin_lock_irq(&lp->lock);
	set_ether_mac(dev, hwaddr->sa_data);
	spin_unlock_irq(&lp->lock);

	return 0;
}

static int uml_net_change_mtu(struct net_device *dev, int new_mtu)
{
	dev->mtu = new_mtu;

	return 0;
}

static void uml_net_get_drvinfo(struct net_device *dev,
				struct ethtool_drvinfo *info)
{
	strcpy(info->driver, DRIVER_NAME);
	strcpy(info->version, "42");
}

static struct ethtool_ops uml_net_ethtool_ops = {
	.get_drvinfo	= uml_net_get_drvinfo,
	.get_link	= ethtool_op_get_link,
};

void uml_net_user_timer_expire(unsigned long _conn)
{
#ifdef undef
	struct connection *conn = (struct connection *)_conn;

	dprintk(KERN_INFO "uml_net_user_timer_expire [%p]\n", conn);
	do_connect(conn);
#endif
}

static void setup_etheraddr(char *str, unsigned char *addr, char *name)
{
	char *end;
	int i;

	if (str == NULL)
		goto random;

	for (i = 0;i < 6; i++) {
		addr[i] = simple_strtoul(str, &end, 16);
		if ((end == str) ||
		   ((*end != ':') && (*end != ',') && (*end != '\0'))) {
			printk(KERN_ERR
			       "setup_etheraddr: failed to parse '%s' "
			       "as an ethernet address\n", str);
			goto random;
		}
		str = end + 1;
	}
	if (is_multicast_ether_addr(addr)) {
		printk(KERN_ERR
		       "Attempt to assign a multicast ethernet address to a "
		       "device disallowed\n");
		goto random;
	}
	if (!is_valid_ether_addr(addr)) {
		printk(KERN_ERR
		       "Attempt to assign an invalid ethernet address to a "
		       "device disallowed\n");
		goto random;
	}
	if (!is_local_ether_addr(addr)) {
		printk(KERN_WARNING
		       "Warning: attempt to assign a globally valid ethernet "
		       "address to a device\n");
		printk(KERN_WARNING "You should better enable the 2nd "
		       "rightmost bit in the first byte of the MAC,\n");
		printk(KERN_WARNING "i.e. %02x:%02x:%02x:%02x:%02x:%02x\n",
		       addr[0] | 0x02, addr[1], addr[2], addr[3], addr[4],
		       addr[5]);
		goto random;
	}
	return;

random:
	printk(KERN_INFO
	       "Choosing a random ethernet address for device %s\n", name);
	random_ether_addr(addr);
}

static DEFINE_SPINLOCK(devices_lock);
static LIST_HEAD(devices);

static struct platform_driver uml_net_driver = {
	.driver = {
		.name  = DRIVER_NAME,
	},
};
static int driver_registered;

static void net_device_release(struct device *dev)
{
	struct uml_net *device = dev->driver_data;
	struct net_device *netdev = device->dev;
	struct uml_net_private *lp = netdev->priv;

	if (lp->remove != NULL)
		(*lp->remove)(&lp->user);
	list_del(&device->list);
	kfree(device);
	free_netdev(netdev);
}

static void eth_configure(int n, void *init, char *mac,
			  struct transport *transport)
{
	struct uml_net *device;
	struct net_device *dev;
	struct uml_net_private *lp;
	int err, size;

	size = transport->private_size + sizeof(struct uml_net_private);

	device = kzalloc(sizeof(*device), GFP_KERNEL);
	if (device == NULL) {
		printk(KERN_ERR "eth_configure failed to allocate struct "
		       "uml_net\n");
		return;
	}

	dev = alloc_etherdev(size);
	if (dev == NULL) {
		printk(KERN_ERR "eth_configure: failed to allocate struct "
		       "net_device for eth%d\n", n);
		goto out_free_device;
	}

	INIT_LIST_HEAD(&device->list);
	device->index = n;

	/* If this name ends up conflicting with an existing registered
	 * netdevice, that is OK, register_netdev{,ice}() will notice this
	 * and fail.
	 */
	snprintf(dev->name, sizeof(dev->name), "eth%d", n);

	setup_etheraddr(mac, device->mac, dev->name);

	printk(KERN_INFO "Netdevice %d ", n);
	printk("(%02x:%02x:%02x:%02x:%02x:%02x) ",
	       device->mac[0], device->mac[1],
	       device->mac[2], device->mac[3],
	       device->mac[4], device->mac[5]);
	printk(": ");

	lp = dev->priv;
	/* This points to the transport private data. It's still clear, but we
	 * must memset it to 0 *now*. Let's help the drivers. */
	memset(lp, 0, size);
	INIT_WORK(&lp->work, uml_dev_close);

	/* sysfs register */
	if (!driver_registered) {
		platform_driver_register(&uml_net_driver);
		driver_registered = 1;
	}
	device->pdev.id = n;
	device->pdev.name = DRIVER_NAME;
	device->pdev.dev.release = net_device_release;
	device->pdev.dev.driver_data = device;
	if (platform_device_register(&device->pdev))
		goto out_free_netdev;
	SET_NETDEV_DEV(dev,&device->pdev.dev);

	device->dev = dev;

	/*
	 * These just fill in a data structure, so there's no failure
	 * to be worried about.
	 */
	(*transport->kern->init)(dev, init);

	*lp = ((struct uml_net_private)
		{ .list  		= LIST_HEAD_INIT(lp->list),
		  .dev 			= dev,
		  .fd 			= -1,
		  .mac 			= { 0xfe, 0xfd, 0x0, 0x0, 0x0, 0x0},
		  .max_packet		= transport->user->max_packet,
		  .protocol 		= transport->kern->protocol,
		  .open 		= transport->user->open,
		  .close 		= transport->user->close,