path: root/arch/um/drivers/net_kern.c

/*
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
 * James Leu (jleu@mindspring.net).
 * 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 = netdev_priv(dev);
	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);
		dev->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);

		dev->stats.rx_bytes += skb->len;
		dev->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);
}

static irqreturn_t uml_net_interrupt(int irq, void *dev_id)
{
	struct net_device *dev = dev_id;
	struct uml_net_private *lp = netdev_priv(dev);
	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 = netdev_priv(dev);
	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)