[Xen-devel] [PATCH v2 2/2] xen-netback: protect resource cleaning on XenBus disconnect

[Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>]

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

Signed-off-by: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
---
 drivers/net/xen-netback/interface.c | 6 ++++--
 drivers/net/xen-netback/xenbus.c    | 2 ++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/xen-netback/interface.c 
b/drivers/net/xen-netback/interface.c
index 41c69b3..c48252a 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -230,18 +230,18 @@ 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;
@@ -250,6 +250,8 @@ 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 3e99071..d82cd71 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);
        }
-- 
1.8.3.1


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