[Xen-changelog] [xen-unstable] [NET] front: Improve correctness when there is no connection to backend driver.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Node ID 41130540891e4c167aa2105b314b5068da27b267
# Parent  a73aa6ec4c763a6a2f91f207e3289acaf36d8853
[NET] front: Improve correctness when there is no connection to backend driver.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
 linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c |   32 +++++++++++--------
 1 files changed, 19 insertions(+), 13 deletions(-)

diff -r a73aa6ec4c76 -r 41130540891e 
linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
--- a/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c      Thu Aug 17 
18:45:59 2006 +0100
+++ b/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c      Thu Aug 17 
19:11:14 2006 +0100
@@ -456,7 +456,8 @@ static int setup_device(struct xenbus_de
 
        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_devic
 
        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
        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, vo
        unsigned long flags;
 
        spin_lock_irqsave(&np->tx_lock, flags);
-       network_tx_buf_gc(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);
-
-       if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx) &&
-           likely(netif_running(dev)))
-               netif_rx_schedule(dev);
 
        return IRQ_HANDLED;
 }

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