[NET] front: Improve correctness when there is no connection to backend driver.

Signed-off-by: Keir Fraser <keir@xensource.com>

diff --git a/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c b/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
index 28e68ca2dd461ae299ae846744982d2efcbe81b2..df5130b8648511a56a281572895a4a2a4a42634b 100644 (file)
--- a/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
+++ b/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
@@ -456,7 +456,8 @@ static int setup_device(struct xenbus_device *dev, struct netfront_info *info)
 
        memcpy(netdev->dev_addr, info->mac, ETH_ALEN);
        err = bind_evtchn_to_irqhandler(info->evtchn, netif_int,
-                                       SA_SAMPLE_RANDOM, netdev->name, netdev);
+                                       SA_SAMPLE_RANDOM, netdev->name,
+                                       netdev);
        if (err < 0)
                goto fail;
        info->irq = err;
@@ -535,11 +536,14 @@ static int network_open(struct net_device *dev)
 
        memset(&np->stats, 0, sizeof(np->stats));
 
-       network_alloc_rx_buffers(dev);
-       np->rx.sring->rsp_event = np->rx.rsp_cons + 1;
-
-       if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx))
-               netif_rx_schedule(dev);
+       spin_lock(&np->rx_lock);
+       if (netif_carrier_ok(dev)) {
+               network_alloc_rx_buffers(dev);
+               np->rx.sring->rsp_event = np->rx.rsp_cons + 1;
+               if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx))
+                       netif_rx_schedule(dev);
+       }
+       spin_unlock(&np->rx_lock);
 
        netif_start_queue(dev);
 
@@ -568,8 +572,7 @@ static void network_tx_buf_gc(struct net_device *dev)
        struct netfront_info *np = netdev_priv(dev);
        struct sk_buff *skb;
 
-       if (unlikely(!netif_carrier_ok(dev)))
-               return;
+       BUG_ON(!netif_carrier_ok(dev));
 
        do {
                prod = np->tx.sring->rsp_prod;
@@ -961,12 +964,15 @@ static irqreturn_t netif_int(int irq, void *dev_id, struct pt_regs *ptregs)
        unsigned long flags;
 
        spin_lock_irqsave(&np->tx_lock, flags);
-       network_tx_buf_gc(dev);
-       spin_unlock_irqrestore(&np->tx_lock, flags);
 
-       if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx) &&
-           likely(netif_running(dev)))
-               netif_rx_schedule(dev);
+       if (likely(netif_carrier_ok(dev))) {
+               network_tx_buf_gc(dev);
+               /* Under tx_lock: protects access to rx shared-ring indexes. */
+               if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx))
+                       netif_rx_schedule(dev);
+       }
+
+       spin_unlock_irqrestore(&np->tx_lock, flags);
 
        return IRQ_HANDLED;
 }