xen-netback: protect resource cleaning on XenBus disconnect

vif->lock is used to protect statistics gathering agents from using the
queue structure during cleaning.

Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 6 insertions, 2 deletions

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index e30ffd29b7e9..579521327b03 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -221,18 +221,18 @@ static struct net_device_stats *xenvif_get_stats(struct net_device *dev)
 {
         struct xenvif *vif = netdev_priv(dev);
         struct xenvif_queue *queue = NULL;
-        unsigned int num_queues = vif->num_queues;
         unsigned long rx_bytes = 0;
         unsigned long rx_packets = 0;
         unsigned long tx_bytes = 0;
         unsigned long tx_packets = 0;
         unsigned int index;
 
+        spin_lock(&vif->lock);
         if (vif->queues == NULL)
                 goto out;
 
         /* Aggregate tx and rx stats from each queue */
-        for (index = 0; index < num_queues; ++index) {
+        for (index = 0; index < vif->num_queues; ++index) {
                 queue = &vif->queues[index];
                 rx_bytes += queue->stats.rx_bytes;
                 rx_packets += queue->stats.rx_packets;
@@ -241,6 +241,8 @@ static struct net_device_stats *xenvif_get_stats(struct net_device *dev)
         }
 
 out:
+        spin_unlock(&vif->lock);
+
         vif->dev->stats.rx_bytes = rx_bytes;
         vif->dev->stats.rx_packets = rx_packets;
         vif->dev->stats.tx_bytes = tx_bytes;
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 34e4af9272ea..85b742e1c42f 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -503,9 +503,11 @@ static void backend_disconnect(struct backend_info *be)
                 for (queue_index = 0; queue_index < be->vif->num_queues; ++queue_index)
                         xenvif_deinit_queue(&be->vif->queues[queue_index]);
 
+                spin_lock(&be->vif->lock);
                 vfree(be->vif->queues);
                 be->vif->num_queues = 0;
                 be->vif->queues = NULL;
+                spin_unlock(&be->vif->lock);
 
                 xenvif_disconnect_ctrl(be->vif);
         }