bitkeeper revision 1.1108.4.1 (40fccf15MMHXnf0_66am3vGFf6fVDA)

Merge net frontend drivers in 2.4 and 2.6.
Fix some bugs that would cause crashes in low-memory conditions.
There may well be some bugs still lurking, but better hidden than
before!

5 files changed, 27 insertions, 884 deletions

diff --git a/.rootkeys b/.rootkeys
index da6f19bdda..b8f1f7b07b 100644
--- a/.rootkeys
+++ b/.rootkeys
@@ -72,7 +72,6 @@
 4097ba837h2tuiweIWp-voNVzCRI6g linux-2.4.26-xen-sparse/arch/xen/drivers/netif/backend/interface.c
 4087cf0d5dudKw_DecIJgOhLlBF_0Q linux-2.4.26-xen-sparse/arch/xen/drivers/netif/backend/main.c
 405853f2wg7JXZJNltspMwOZJklxgw linux-2.4.26-xen-sparse/arch/xen/drivers/netif/frontend/Makefile
-405853f6nbeazrNyEWNHBuoSg2PiPA linux-2.4.26-xen-sparse/arch/xen/drivers/netif/frontend/main.c
 4097ba83Qy2eafeFUhGhm6_4iMIIDw linux-2.4.26-xen-sparse/arch/xen/drivers/netif/netif.h
 3e5a4e65lWzkiPXsZdzPt2RNnJGG1g linux-2.4.26-xen-sparse/arch/xen/kernel/Makefile
 4075806dE5mQwlVUf8-t3YXjiMMWDQ linux-2.4.26-xen-sparse/arch/xen/kernel/ctrl_if.c
@@ -199,7 +198,7 @@
 40f56239DoibTX6R-ZYd3QTXAB8_TA linux-2.6.7-xen-sparse/drivers/xen/evtchn/evtchn.c
 40f56239lrg_Ob0BJ8WBFS1zeg2CYw linux-2.6.7-xen-sparse/drivers/xen/net/Kconfig
 40f56239Wd4k_ycG_mFsSO1r5xKdtQ linux-2.6.7-xen-sparse/drivers/xen/net/Makefile
-40f56239vUsbJCS9tGFfRVi1YZlGEg linux-2.6.7-xen-sparse/drivers/xen/net/network.c
+405853f6nbeazrNyEWNHBuoSg2PiPA linux-2.6.7-xen-sparse/drivers/xen/net/network.c
 40f56239YAjS52QG2FIAQpHDZAdGHg linux-2.6.7-xen-sparse/include/asm-xen/asm-i386/desc.h
 40f5623anSzpuEHgiNmQ56fIRfCoaQ linux-2.6.7-xen-sparse/include/asm-xen/asm-i386/e820.h
 40f5623akIoBsQ3KxSB2kufkbgONXQ linux-2.6.7-xen-sparse/include/asm-xen/asm-i386/fixmap.h
diff --git a/linux-2.4.26-xen-sparse/arch/xen/drivers/netif/backend/main.c b/linux-2.4.26-xen-sparse/arch/xen/drivers/netif/backend/main.c
index 851cc30285..868f7d0a81 100644
--- a/linux-2.4.26-xen-sparse/arch/xen/drivers/netif/backend/main.c
+++ b/linux-2.4.26-xen-sparse/arch/xen/drivers/netif/backend/main.c
@@ -495,7 +495,7 @@ static void net_tx_action(unsigned long unused)
 
         pending_idx = pending_ring[MASK_PEND_IDX(pending_cons)];
 
-        if ( unlikely((skb = dev_alloc_skb(PKT_PROT_LEN)) == NULL) )
+        if ( unlikely((skb = alloc_skb(PKT_PROT_LEN+16, GFP_ATOMIC)) == NULL) )
         {
             DPRINTK("Can't allocate a skb in start_xmit.\n");
             make_tx_response(netif, txreq.id, NETIF_RSP_ERROR);
@@ -503,6 +503,9 @@ static void net_tx_action(unsigned long unused)
             break;
         }
 
+        /* Packets passed to netif_rx() must have some headroom. */
+        skb_reserve(skb, 16);
+
         mcl[0].op = __HYPERVISOR_update_va_mapping_otherdomain;
         mcl[0].args[0] = MMAP_VADDR(pending_idx) >> PAGE_SHIFT;
         mcl[0].args[1] = (txreq.addr & PAGE_MASK) | __PAGE_KERNEL;
diff --git a/linux-2.4.26-xen-sparse/arch/xen/drivers/netif/frontend/main.c b/linux-2.4.26-xen-sparse/arch/xen/drivers/netif/frontend/main.c
deleted file mode 100644
index ff75096bd8..0000000000
--- a/linux-2.4.26-xen-sparse/arch/xen/drivers/netif/frontend/main.c
+++ /dev/null
@@ -1,867 +0,0 @@
-/******************************************************************************
- * arch/xen/drivers/netif/frontend/main.c
- * 
- * Virtual network driver for conversing with remote driver backends.
- * 
- * Copyright (c) 2002-2004, K A Fraser
- */
-
-#include <linux/config.h>
-#include <linux/module.h>
-
-#include <linux/kernel.h>
-#include <linux/sched.h>
-#include <linux/slab.h>
-#include <linux/string.h>
-#include <linux/errno.h>
-
-#include <linux/netdevice.h>
-#include <linux/inetdevice.h>
-#include <linux/etherdevice.h>
-#include <linux/skbuff.h>
-#include <linux/init.h>
-
-#include <asm/io.h>
-#include <net/sock.h>
-#include <net/pkt_sched.h>
-
-#include <asm/evtchn.h>
-#include <asm/ctrl_if.h>
-
-#include <asm/page.h>
-
-#include "../netif.h"
-
-#define RX_BUF_SIZE ((PAGE_SIZE/2)+1) /* Fool the slab allocator :-) */
-
-static void network_tx_buf_gc(struct net_device *dev);
-static void network_alloc_rx_buffers(struct net_device *dev);
-
-static unsigned long rx_pfn_array[NETIF_RX_RING_SIZE];
-static multicall_entry_t rx_mcl[NETIF_RX_RING_SIZE+1];
-static mmu_update_t rx_mmu[NETIF_RX_RING_SIZE];
-
-static struct list_head dev_list;
-
-struct net_private
-{
-    struct list_head list;
-    struct net_device *dev;
-
-    struct net_device_stats stats;
-    NETIF_RING_IDX rx_resp_cons, tx_resp_cons;
-    unsigned int tx_full;
-    
-    netif_tx_interface_t *tx;
-    netif_rx_interface_t *rx;
-
-    spinlock_t   tx_lock;
-    spinlock_t   rx_lock;
-
-    unsigned int handle;
-    unsigned int evtchn;
-    unsigned int irq;
-
-    /* What is the status of our connection to the remote backend? */
-#define BEST_CLOSED       0
-#define BEST_DISCONNECTED 1
-#define BEST_CONNECTED    2
-    unsigned int backend_state;
-
-    /* Is this interface open or closed (down or up)? */
-#define UST_CLOSED        0
-#define UST_OPEN          1
-    unsigned int user_state;
-
-    /*
-     * {tx,rx}_skbs store outstanding skbuffs. The first entry in each
-     * array is an index into a chain of free entries.
-     */
-    struct sk_buff *tx_skbs[NETIF_TX_RING_SIZE+1];
-    struct sk_buff *rx_skbs[NETIF_RX_RING_SIZE+1];
-};
-
-/* Access macros for acquiring freeing slots in {tx,rx}_skbs[]. */
-#define ADD_ID_TO_FREELIST(_list, _id)             \
-    (_list)[(_id)] = (_list)[0];                   \
-    (_list)[0]     = (void *)(unsigned long)(_id);
-#define GET_ID_FROM_FREELIST(_list)                \
- ({ unsigned long _id = (unsigned long)(_list)[0]; \
-    (_list)[0]  = (_list)[_id];                    \
-    (unsigned short)_id; })
-
-static struct net_device *find_dev_by_handle(unsigned int handle)
-{
-    struct list_head *ent;
-    struct net_private *np;
-    list_for_each ( ent, &dev_list )
-    {
-        np = list_entry(ent, struct net_private, list);
-        if ( np->handle == handle )
-            return np->dev;
-    }
-    return NULL;
-}
-
-/** Network interface info. */
-struct netif_ctrl {
-    /** Number of interfaces. */
-    int interface_n;
-    /** Number of connected interfaces. */
-    int connected_n;
-    /** Error code. */
-    int err;
-};
-
-static struct netif_ctrl netctrl;
-
-static void netctrl_init(void)
-{
-    memset(&netctrl, 0, sizeof(netctrl));
-    netctrl.interface_n = -1;
-}
-
-/** Get or set a network interface error.
- */
-static int netctrl_err(int err)
-{
-    if(err < 0 && !netctrl.err){
-        netctrl.err = err;
-        printk(KERN_WARNING "%s> err=%d\n", __FUNCTION__, err);
-    }
-    return netctrl.err;
-}
-
-/** Test if all network interfaces are connected.
- *
- * @return 1 if all connected, 0 if not, negative error code otherwise
- */
-static int netctrl_connected(void)
-{
-    int ok = 0;
-    ok = (netctrl.err ? netctrl.err :
-          (netctrl.connected_n == netctrl.interface_n));
-    return ok;
-}
-
-/** Count the connected network interfaces.
- *
- * @return connected count
- */
-static int netctrl_connected_count(void)
-{
-    
-    struct list_head *ent;
-    struct net_private *np;
-    unsigned int connected;
-
-    connected = 0;
-    
-    list_for_each(ent, &dev_list)
-    {
-        np = list_entry(ent, struct net_private, list);
-        if ( np->backend_state == BEST_CONNECTED )
-            connected++;
-    }
-
-    netctrl.connected_n = connected;
-    return connected;
-}
-
-static int network_open(struct net_device *dev)
-{
-    struct net_private *np = dev->priv;
-
-    memset(&np->stats, 0, sizeof(np->stats));
-
-    np->user_state = UST_OPEN;
-
-    network_alloc_rx_buffers(dev);
-    np->rx->event = np->rx_resp_cons + 1;
-
-    netif_start_queue(dev);
-
-    return 0;
-}
-
-
-static void network_tx_buf_gc(struct net_device *dev)
-{
-    NETIF_RING_IDX i, prod;
-    unsigned short id;
-    struct net_private *np = dev->priv;
-    struct sk_buff *skb;
-
-    if ( np->backend_state != BEST_CONNECTED )
-        return;
-
-    do {
-        prod = np->tx->resp_prod;
-
-        for ( i = np->tx_resp_cons; i != prod; i++ )
-        {
-            id  = np->tx->ring[MASK_NETIF_TX_IDX(i)].resp.id;
-            skb = np->tx_skbs[id];
-            ADD_ID_TO_FREELIST(np->tx_skbs, id);
-            dev_kfree_skb_any(skb);
-        }
-        
-        np->tx_resp_cons = prod;
-        
-        /*
-         * Set a new event, then check for race with update of tx_cons. Note
-         * that it is essential to schedule a callback, no matter how few
-         * buffers are pending. Even if there is space in the transmit ring,
-         * higher layers may be blocked because too much data is outstanding:
-         * in such cases notification from Xen is likely to be the only kick
-         * that we'll get.
-         */
-        np->tx->event = 
-            prod + ((np->tx->req_prod - prod) >> 1) + 1;
-        mb();
-    }
-    while ( prod != np->tx->resp_prod );
-
-    if ( np->tx_full && 
-         ((np->tx->req_prod - prod) < NETIF_TX_RING_SIZE) )
-    {
-        np->tx_full = 0;
-        if ( np->user_state == UST_OPEN )
-            netif_wake_queue(dev);
-    }
-}
-
-
-static void network_alloc_rx_buffers(struct net_device *dev)
-{
-    unsigned short id;
-    struct net_private *np = dev->priv;
-    struct sk_buff *skb;
-    NETIF_RING_IDX i = np->rx->req_prod;
-    int nr_pfns = 0;
-
-    /* Make sure the batch is large enough to be worthwhile (1/2 ring). */
-    if ( unlikely((i - np->rx_resp_cons) > (NETIF_RX_RING_SIZE/2)) || 
-         unlikely(np->backend_state != BEST_CONNECTED) )
-        return;
-
-    do {
-        skb = dev_alloc_skb(RX_BUF_SIZE);
-        if ( unlikely(skb == NULL) )
-            break;
-
-        skb->dev = dev;
-
-        if ( unlikely(((unsigned long)skb->head & (PAGE_SIZE-1)) != 0) )
-            panic("alloc_skb needs to provide us page-aligned buffers.");
-
-        id = GET_ID_FROM_FREELIST(np->rx_skbs);
-
-        np->rx_skbs[id] = skb;
-        
-        np->rx->ring[MASK_NETIF_RX_IDX(i)].req.id = id;
-        
-        rx_pfn_array[nr_pfns] = virt_to_machine(skb->head) >> PAGE_SHIFT;
-
-        rx_mcl[nr_pfns].op = __HYPERVISOR_update_va_mapping;
-        rx_mcl[nr_pfns].args[0] = (unsigned long)skb->head >> PAGE_SHIFT;
-        rx_mcl[nr_pfns].args[1] = 0;
-        rx_mcl[nr_pfns].args[2] = 0;
-
-        nr_pfns++;
-    }
-    while ( (++i - np->rx_resp_cons) != NETIF_RX_RING_SIZE );
-
-    /*
-     * We may have allocated buffers which have entries outstanding in the page
-     * update queue -- make sure we flush those first!
-     */
-    flush_page_update_queue();
-
-    /* After all PTEs have been zapped we blow away stale TLB entries. */
-    rx_mcl[nr_pfns-1].args[2] = UVMF_FLUSH_TLB;
-
-    /* Give away a batch of pages. */
-    rx_mcl[nr_pfns].op = __HYPERVISOR_dom_mem_op;
-    rx_mcl[nr_pfns].args[0] = MEMOP_decrease_reservation;
-    rx_mcl[nr_pfns].args[1] = (unsigned long)rx_pfn_array;
-    rx_mcl[nr_pfns].args[2] = (unsigned long)nr_pfns;
-
-    /* Zap PTEs and give away pages in one big multicall. */
-    (void)HYPERVISOR_multicall(rx_mcl, nr_pfns+1);
-
-    /* Check return status of HYPERVISOR_dom_mem_op(). */
-    if ( rx_mcl[nr_pfns].args[5] != nr_pfns )
-        panic("Unable to reduce memory reservation\n");
-
-    np->rx->req_prod = i;
-}
-
-
-static int network_start_xmit(struct sk_buff *skb, struct net_device *dev)
-{
-    unsigned short id;
-    struct net_private *np = (struct net_private *)dev->priv;
-    netif_tx_request_t *tx;
-    NETIF_RING_IDX i;
-
-    if ( unlikely(np->tx_full) )
-    {
-        printk(KERN_ALERT "%s: full queue wasn't stopped!\n", dev->name);
-        netif_stop_queue(dev);
-        return -ENOBUFS;
-    }
-
-    if ( unlikely((((unsigned long)skb->data & ~PAGE_MASK) + skb->len) >=
-                  PAGE_SIZE) )
-    {
-        struct sk_buff *new_skb = dev_alloc_skb(RX_BUF_SIZE);
-        if ( unlikely(new_skb == NULL) )
-            return 1;
-        skb_put(new_skb, skb->len);
-        memcpy(new_skb->data, skb->data, skb->len);
-        dev_kfree_skb(skb);
-        skb = new_skb;
-    }
-    
-    spin_lock_irq(&np->tx_lock);
-
-    if ( np->backend_state != BEST_CONNECTED )
-    {
-        spin_unlock_irq(&np->tx_lock);
-        return 1;
-    }
-
-    i = np->tx->req_prod;
-
-    id = GET_ID_FROM_FREELIST(np->tx_skbs);
-    np->tx_skbs[id] = skb;
-
-    tx = &np->tx->ring[MASK_NETIF_TX_IDX(i)].req;
-
-    tx->id   = id;
-    tx->addr = virt_to_machine(skb->data);
-    tx->size = skb->len;
-
-    wmb();
-    np->tx->req_prod = i + 1;
-
-    network_tx_buf_gc(dev);
-
-    if ( (i - np->tx_resp_cons) == (NETIF_TX_RING_SIZE - 1) )
-    {
-        np->tx_full = 1;
-        netif_stop_queue(dev);
-    }
-
-    spin_unlock_irq(&np->tx_lock);
-
-    np->stats.tx_bytes += skb->len;
-    np->stats.tx_packets++;
-
-    /* Only notify Xen if there are no outstanding responses. */
-    mb();
-    if ( np->tx->resp_prod == i )
-        notify_via_evtchn(np->evtchn);
-
-    return 0;
-}
-
-
-static void netif_int(int irq, void *dev_id, struct pt_regs *ptregs)
-{
-    struct net_device *dev = dev_id;
-    struct net_private *np = dev->priv;
-    unsigned long flags;
-
-    spin_lock_irqsave(&np->tx_lock, flags);
-    network_tx_buf_gc(dev);
-    spin_unlock_irqrestore(&np->tx_lock, flags);
-
-    if ( (np->rx_resp_cons != np->rx->resp_prod) &&
-         (np->user_state == UST_OPEN) )
-        netif_rx_schedule(dev);
-}
-
-
-static int netif_poll(struct net_device *dev, int *pbudget)
-{
-    struct net_private *np = dev->priv;
-    struct sk_buff *skb;
-    netif_rx_response_t *rx;
-    NETIF_RING_IDX i;
-    mmu_update_t *mmu = rx_mmu;
-    multicall_entry_t *mcl = rx_mcl;
-    int work_done, budget, more_to_do = 1;
-    struct sk_buff_head rxq;
-    unsigned long flags;
-
-    spin_lock(&np->rx_lock);
-
-    if ( np->backend_state != BEST_CONNECTED )
-    {
-        spin_unlock(&np->rx_lock);
-        return 0;
-    }
-
-    skb_queue_head_init(&rxq);
-
-    if ( (budget = *pbudget) > dev->quota )
-        budget = dev->quota;
-
-    for ( i = np->rx_resp_cons, work_done = 0; 
-          (i != np->rx->resp_prod) && (work_done < budget); 
-          i++, work_done++ )
-    {
-        rx = &np->rx->ring[MASK_NETIF_RX_IDX(i)].resp;
-
-        skb = np->rx_skbs[rx->id];
-        ADD_ID_TO_FREELIST(np->rx_skbs, rx->id);
-
-        if ( unlikely(rx->status <= 0) )
-        {
-            /* Gate this error. We get a (valid) slew of them on suspend. */
-            if ( np->user_state != UST_OPEN )
-                printk(KERN_ALERT "bad buffer on RX ring!(%d)\n", rx->status);
-            dev_kfree_skb(skb);
-            continue;
-        }
-
-        skb->data = skb->tail = skb->head + (rx->addr & ~PAGE_MASK);
-        skb_put(skb, rx->status);
-
-        np->stats.rx_packets++;
-        np->stats.rx_bytes += rx->status;
-
-        /* Remap the page. */
-        mmu->ptr  = (rx->addr & PAGE_MASK) | MMU_MACHPHYS_UPDATE;
-        mmu->val  = __pa(skb->head) >> PAGE_SHIFT;
-        mmu++;
-        mcl->op = __HYPERVISOR_update_va_mapping;
-        mcl->args[0] = (unsigned long)skb->head >> PAGE_SHIFT;
-        mcl->args[1] = (rx->addr & PAGE_MASK) | __PAGE_KERNEL;
-        mcl->args[2] = 0;
-        mcl++;
-
-        phys_to_machine_mapping[__pa(skb->head) >> PAGE_SHIFT] = 
-            rx->addr >> PAGE_SHIFT;
-
-        __skb_queue_tail(&rxq, skb);
-    }
-
-    /* Do all the remapping work, and M->P updates, in one big hypercall. */
-    if ( likely((mcl - rx_mcl) != 0) )
-    {
-        mcl->op = __HYPERVISOR_mmu_update;
-        mcl->args[0] = (unsigned long)rx_mmu;
-        mcl->args[1] = mmu - rx_mmu;
-        mcl->args[2] = 0;
-        mcl++;
-        (void)HYPERVISOR_multicall(rx_mcl, mcl - rx_mcl);
-    }
-
-    while ( (skb = __skb_dequeue(&rxq)) != NULL )
-    {
-        /* Set the shared-info area, which is hidden behind the real data. */
-        atomic_set(&(skb_shinfo(skb)->dataref), 1);
-        skb_shinfo(skb)->nr_frags = 0;
-        skb_shinfo(skb)->frag_list = NULL;
-
-        /* Ethernet-specific work. Delayed to here as it peeks the header. */
-        skb->protocol = eth_type_trans(skb, dev);
-
-        /* Pass it up. */
-        netif_rx(skb);
-        dev->last_rx = jiffies;
-    }
-
-    np->rx_resp_cons = i;
-
-    network_alloc_rx_buffers(dev);
-
-    *pbudget   -= work_done;
-    dev->quota -= work_done;
-
-    if ( work_done < budget )
-    {
-        local_irq_save(flags);
-
-        np->rx->event = i + 1;
-    
-        /* Deal with hypervisor racing our resetting of rx_event. */
-        mb();
-        if ( np->rx->resp_prod == i )
-        {
-            __netif_rx_complete(dev);
-            more_to_do = 0;
-        }
-
-        local_irq_restore(flags);
-    }
-
-    spin_unlock(&np->rx_lock);
-
-    return more_to_do;
-}
-
-
-static int network_close(struct net_device *dev)
-{
-    struct net_private *np = dev->priv;
-    np->user_state = UST_CLOSED;
-    netif_stop_queue(np->dev);
-    return 0;
-}
-
-
-static struct net_device_stats *network_get_stats(struct net_device *dev)
-{
-    struct net_private *np = (struct net_private *)dev->priv;
-    return &np->stats;
-}
-
-
-static void network_connect(struct net_device *dev,
-                            netif_fe_interface_status_changed_t *status)
-{
-    struct net_private *np;
-    int i, requeue_idx;
-    netif_tx_request_t *tx;
-
-    np = dev->priv;
-    spin_lock_irq(&np->rx_lock);
-    spin_lock(&np->tx_lock);
-
-    /* Recovery procedure: */
-
-    /* Step 1: Reinitialise variables. */
-    np->rx_resp_cons = np->tx_resp_cons = np->tx_full = 0;
-    np->rx->event = 1;
-
-    /* Step 2: Rebuild the RX and TX ring contents.
-     * NB. We could just free the queued TX packets now but we hope
-     * that sending them out might do some good.  We have to rebuild
-     * the RX ring because some of our pages are currently flipped out
-     * so we can't just free the RX skbs.
-     * NB2. Freelist index entries are always going to be less than
-     *  __PAGE_OFFSET, whereas pointers to skbs will always be equal or
-     * greater than __PAGE_OFFSET: we use this property to distinguish
-     * them.
-     */
-
-    /* Rebuild the TX buffer freelist and the TX ring itself.
-     * NB. This reorders packets.  We could keep more private state
-     * to avoid this but maybe it doesn't matter so much given the
-     * interface has been down.
-     */
-    for ( requeue_idx = 0, i = 1; i <= NETIF_TX_RING_SIZE; i++ )
-    {
-            if ( (unsigned long)np->tx_skbs[i] >= __PAGE_OFFSET )
-            {
-                struct sk_buff *skb = np->tx_skbs[i];
-                
-                tx = &np->tx->ring[requeue_idx++].req;
-                
-                tx->id   = i;
-                tx->addr = virt_to_machine(skb->data);
-                tx->size = skb->len;
-                
-                np->stats.tx_bytes += skb->len;
-                np->stats.tx_packets++;
-            }
-    }
-    wmb();
-    np->tx->req_prod = requeue_idx;
-
-    /* Rebuild the RX buffer freelist and the RX ring itself. */
-    for ( requeue_idx = 0, i = 1; i <= NETIF_RX_RING_SIZE; i++ )
-        if ( (unsigned long)np->rx_skbs[i] >= __PAGE_OFFSET )
-            np->rx->ring[requeue_idx++].req.id = i;
-    wmb();                
-    np->rx->req_prod = requeue_idx;
-
-    /* Step 3: All public and private state should now be sane.  Get
-     * ready to start sending and receiving packets and give the driver
-     * domain a kick because we've probably just requeued some
-     * packets.
-     */
-    np->backend_state = BEST_CONNECTED;
-    notify_via_evtchn(status->evtchn);  
-    network_tx_buf_gc(dev);
-
-    if ( np->user_state == UST_OPEN )
-        netif_start_queue(dev);
-
-    spin_unlock(&np->tx_lock);
-    spin_unlock_irq(&np->rx_lock);
-}
-
-static void netif_status_change(netif_fe_interface_status_changed_t *status)
-{
-    ctrl_msg_t                   cmsg;
-    netif_fe_interface_connect_t up;
-    struct net_device *dev;
-    struct net_private *np;
-    
-    if ( netctrl.interface_n <= 0 )
-    {
-        printk(KERN_WARNING "Status change: no interfaces\n");
-        return;
-    }
-
-    dev = find_dev_by_handle(status->handle);
-    if(!dev){
-        printk(KERN_WARNING "Status change: invalid netif handle %u\n",
-               status->handle);
-         return;
-    }
-    np  = dev->priv;
-    
-    switch ( status->status )
-    {
-    case NETIF_INTERFACE_STATUS_DESTROYED:
-        printk(KERN_WARNING "Unexpected netif-DESTROYED message in state %d\n",
-               np->backend_state);
-        break;
-
-    case NETIF_INTERFACE_STATUS_DISCONNECTED:
-        if ( np->backend_state != BEST_CLOSED )
-        {
-            printk(KERN_WARNING "Unexpected netif-DISCONNECTED message"
-                   " in state %d\n", np->backend_state);
-	    printk(KERN_INFO "Attempting to reconnect network interface\n");
-
-            /* Begin interface recovery.
-	     *
-	     * NB. Whilst we're recovering, we turn the carrier state off.  We
-	     * take measures to ensure that this device isn't used for
-	     * anything.  We also stop the queue for this device.  Various
-	     * different approaches (e.g. continuing to buffer packets) have
-	     * been tested but don't appear to improve the overall impact on
-             * TCP connections.
-	     *
-             * TODO: (MAW) Change the Xend<->Guest protocol so that a recovery
-             * is initiated by a special "RESET" message - disconnect could
-             * just mean we're not allowed to use this interface any more.
-             */
-
-            /* Stop old i/f to prevent errors whilst we rebuild the state. */
-            spin_lock_irq(&np->tx_lock);
-            spin_lock(&np->rx_lock);
-            netif_stop_queue(dev);
-            np->backend_state = BEST_DISCONNECTED;
-            spin_unlock(&np->rx_lock);
-            spin_unlock_irq(&np->tx_lock);
-
-            /* Free resources. */
-            free_irq(np->irq, dev);
-            unbind_evtchn_from_irq(np->evtchn);
-	    free_page((unsigned long)np->tx);
-            free_page((unsigned long)np->rx);
-        }
-
-        /* Move from CLOSED to DISCONNECTED state. */
-        np->tx = (netif_tx_interface_t *)__get_free_page(GFP_KERNEL);
-        np->rx = (netif_rx_interface_t *)__get_free_page(GFP_KERNEL);
-        memset(np->tx, 0, PAGE_SIZE);
-        memset(np->rx, 0, PAGE_SIZE);
-        np->backend_state = BEST_DISCONNECTED;
-
-        /* Construct an interface-CONNECT message for the domain controller. */
-        cmsg.type      = CMSG_NETIF_FE;
-        cmsg.subtype   = CMSG_NETIF_FE_INTERFACE_CONNECT;
-        cmsg.length    = sizeof(netif_fe_interface_connect_t);
-        up.handle      = status->handle;
-        up.tx_shmem_frame = virt_to_machine(np->tx) >> PAGE_SHIFT;
-        up.rx_shmem_frame = virt_to_machine(np->rx) >> PAGE_SHIFT;
-        memcpy(cmsg.msg, &up, sizeof(up));
-        
-        /* Tell the controller to bring up the interface. */
-        ctrl_if_send_message_block(&cmsg, NULL, 0, TASK_UNINTERRUPTIBLE);
-        break;
-
-    case NETIF_INTERFACE_STATUS_CONNECTED:
-        if ( np->backend_state == BEST_CLOSED )
-        {
-            printk(KERN_WARNING "Unexpected netif-CONNECTED message"
-                   " in state %d\n", np->backend_state);
-            break;
-        }
-
-        memcpy(dev->dev_addr, status->mac, ETH_ALEN);
-
-        network_connect(dev, status);
-
-        np->evtchn = status->evtchn;
-        np->irq = bind_evtchn_to_irq(np->evtchn);
-        (void)request_irq(np->irq, netif_int, SA_SAMPLE_RANDOM, 
-                          dev->name, dev);
-        
-        netctrl_connected_count();
-        break;
-
-    default:
-        printk(KERN_WARNING "Status change to unknown value %d\n", 
-               status->status);
-        break;
-    }
-}
-
-/** Create a network device.
- * @param handle device handle
- * @param val return parameter for created device
- * @return 0 on success, error code otherwise
- */
-static int create_netdev(int handle, struct net_device **val)
-{
-    int i, err = 0;
-    struct net_device *dev = NULL;
-    struct net_private *np = NULL;
-
-    if ( (dev = alloc_etherdev(sizeof(struct net_private))) == NULL )
-    {
-        printk(KERN_WARNING "%s> alloc_etherdev failed.\n", __FUNCTION__);
-        err = -ENOMEM;
-        goto exit;
-    }
-
-    np                = dev->priv;
-    np->backend_state = BEST_CLOSED;
-    np->user_state    = UST_CLOSED;
-    np->handle        = handle;
-    
-    spin_lock_init(&np->tx_lock);
-    spin_lock_init(&np->rx_lock);
-
-    /* Initialise {tx,rx}_skbs to be a free chain containing every entry. */
-    for ( i = 0; i <= NETIF_TX_RING_SIZE; i++ )
-        np->tx_skbs[i] = (void *)(i+1);
-    for ( i = 0; i <= NETIF_RX_RING_SIZE; i++ )
-        np->rx_skbs[i] = (void *)(i+1);
-
-    dev->open            = network_open;
-    dev->hard_start_xmit = network_start_xmit;
-    dev->stop            = network_close;
-    dev->get_stats       = network_get_stats;
-    dev->poll            = netif_poll;
-    dev->weight          = 64;
-    
-    if ( (err = register_netdev(dev)) != 0 )
-    {
-        printk(KERN_WARNING "%s> register_netdev err=%d\n", __FUNCTION__, err);
-        goto exit;
-    }
-    np->dev = dev;
-    list_add(&np->list, &dev_list);
-
-  exit:
-    if ( (err != 0) && (dev != NULL ) )
-        kfree(dev);
-    else if ( val != NULL )
-        *val = dev;
-    return err;
-}
-
-/*
- * Initialize the network control interface. Set the number of network devices
- * and create them.
- */
-static void netif_driver_status_change(
-    netif_fe_driver_status_changed_t *status)
-{
-    int err = 0;
-    int i;
-    
-    netctrl.interface_n = status->nr_interfaces;
-    netctrl.connected_n = 0;
-
-    for ( i = 0; i < netctrl.interface_n; i++ )
-    {
-        if ( (err = create_netdev(i, NULL)) != 0 )
-        {
-            netctrl_err(err);
-            break;
-        }
-    }
-}
-
-static void netif_ctrlif_rx(ctrl_msg_t *msg, unsigned long id)
-{
-    int respond = 1;
-
-    switch ( msg->subtype )
-    {
-    case CMSG_NETIF_FE_INTERFACE_STATUS_CHANGED:
-        if ( msg->length != sizeof(netif_fe_interface_status_changed_t) )
-            goto error;
-        netif_status_change((netif_fe_interface_status_changed_t *)
-                            &msg->msg[0]);
-        break;
-
-    case CMSG_NETIF_FE_DRIVER_STATUS_CHANGED:
-        if ( msg->length != sizeof(netif_fe_driver_status_changed_t) )
-            goto error;
-        netif_driver_status_change((netif_fe_driver_status_changed_t *)
-                                   &msg->msg[0]);
-        /* Message is a response */
-        respond = 0;
-        break;
-
-    error:
-    default:
-        msg->length = 0;
-        break;
-    }
-
-    if ( respond )
-        ctrl_if_send_response(msg);
-}
-
-
-static int __init netif_init(void)
-{
-    ctrl_msg_t                       cmsg;
-    netif_fe_driver_status_changed_t st;
-    int err = 0, wait_i, wait_n = 20;
-
-    if ( (start_info.flags & SIF_INITDOMAIN) ||
-         (start_info.flags & SIF_NET_BE_DOMAIN) )
-        return 0;
-
-    printk("Initialising Xen virtual ethernet frontend driver");
-
-    INIT_LIST_HEAD(&dev_list);
-
-    netctrl_init();
-
-    (void)ctrl_if_register_receiver(CMSG_NETIF_FE, netif_ctrlif_rx,
-                                    CALLBACK_IN_BLOCKING_CONTEXT);
-
-    /* Send a driver-UP notification to the domain controller. */
-    cmsg.type      = CMSG_NETIF_FE;
-    cmsg.subtype   = CMSG_NETIF_FE_DRIVER_STATUS_CHANGED;
-    cmsg.length    = sizeof(netif_fe_driver_status_changed_t);
-    st.status      = NETIF_DRIVER_STATUS_UP;
-    st.nr_interfaces = 0;
-    memcpy(cmsg.msg, &st, sizeof(st));
-    ctrl_if_send_message_block(&cmsg, NULL, 0, TASK_UNINTERRUPTIBLE);
-
-    /* Wait for all interfaces to be connected. */
-    for ( wait_i = 0; ; wait_i++)
-    {
-        if ( (err = (wait_i < wait_n) ? netctrl_connected() : -ENETDOWN) != 0 )
-        {
-            err = (err > 0) ? 0 : err;
-            break;
-        }
-        set_current_state(TASK_INTERRUPTIBLE);
-        schedule_timeout(1);
-     }
-
-    if ( err )
-        ctrl_if_unregister_receiver(CMSG_NETIF_FE, netif_ctrlif_rx);
-
-    return err;
-}
-
-__initcall(netif_init);
diff --git a/linux-2.4.26-xen-sparse/mkbuildtree b/linux-2.4.26-xen-sparse/mkbuildtree
index 5dba6c03d5..7cdc0af60d 100755
--- a/linux-2.4.26-xen-sparse/mkbuildtree
+++ b/linux-2.4.26-xen-sparse/mkbuildtree
@@ -225,5 +225,5 @@ ln -sf ../../i386/mm/extable.c
 ln -sf ../../i386/mm/pageattr.c 
 cd ../drivers/console
 ln -sf ../../../../${LINUX_26}/drivers/xen/console/console.c 
-#cd ../netif/frontend
-#ln -sf ../../../../../${LINUX_26}/drivers/xen/net/network.c main.c
+cd ../netif/frontend
+ln -sf ../../../../../${LINUX_26}/drivers/xen/net/network.c main.c
diff --git a/linux-2.6.7-xen-sparse/drivers/xen/net/network.c b/linux-2.6.7-xen-sparse/drivers/xen/net/network.c
index d48192fd03..ea0fa45f03 100644
--- a/linux-2.6.7-xen-sparse/drivers/xen/net/network.c
+++ b/linux-2.6.7-xen-sparse/drivers/xen/net/network.c
@@ -1,6 +1,4 @@
 /******************************************************************************
- * network.c
- * 
  * Virtual network driver for conversing with remote driver backends.
  * 
  * Copyright (c) 2002-2004, K A Fraser
@@ -8,13 +6,12 @@
 
 #include <linux/config.h>
 #include <linux/module.h>
-
+#include <linux/version.h>
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/errno.h>
-
 #include <linux/netdevice.h>
 #include <linux/inetdevice.h>
 #include <linux/etherdevice.h>
@@ -30,7 +27,13 @@
 
 #include <asm/page.h>
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
 #include <asm-xen/netif.h>
+#else
+#include "../netif.h"
+#define irqreturn_t void
+#define IRQ_HANDLED
+#endif
 
 #define RX_BUF_SIZE ((PAGE_SIZE/2)+1) /* Fool the slab allocator :-) */
 
@@ -368,7 +371,7 @@ static int network_start_xmit(struct sk_buff *skb, struct net_device *dev)
 }
 
 
-static irqreturn_t netif_int(int irq, void *dev_id, struct pt_regs *ptregs)
+static void netif_int(int irq, void *dev_id, struct pt_regs *ptregs)
 {
     struct net_device *dev = dev_id;
     struct net_private *np = dev->priv;
@@ -381,8 +384,6 @@ static irqreturn_t netif_int(int irq, void *dev_id, struct pt_regs *ptregs)
     if ( (np->rx_resp_cons != np->rx->resp_prod) &&
          (np->user_state == UST_OPEN) )
         netif_rx_schedule(dev);
-
-    return IRQ_HANDLED;
 }
 
 
@@ -417,18 +418,25 @@ static int netif_poll(struct net_device *dev, int *pbudget)
     {
         rx = &np->rx->ring[MASK_NETIF_RX_IDX(i)].resp;
 
-        skb = np->rx_skbs[rx->id];
-        ADD_ID_TO_FREELIST(np->rx_skbs, rx->id);
-
+        /*
+         * An error here is very odd. Usually indicates a backend bug,
+         * low-memory condition, or that we didn't have reservation headroom.
+         * Whatever - print an error and queue the id again straight away.
+         */
         if ( unlikely(rx->status <= 0) )
         {
             /* Gate this error. We get a (valid) slew of them on suspend. */
-            if ( np->user_state != UST_OPEN )
+            if ( np->user_state == UST_OPEN )
                 printk(KERN_ALERT "bad buffer on RX ring!(%d)\n", rx->status);
-            dev_kfree_skb(skb);
+            np->rx->ring[MASK_NETIF_RX_IDX(np->rx->req_prod)].req.id = rx->id;
+            wmb();
+            np->rx->req_prod++;
             continue;
         }
 
+        skb = np->rx_skbs[rx->id];
+        ADD_ID_TO_FREELIST(np->rx_skbs, rx->id);
+
         skb->data = skb->tail = skb->head + (rx->addr & ~PAGE_MASK);
         skb_put(skb, rx->status);