[PATCH 4.9 075/172] xen-netback: protect resource cleaning on XenBus disconnect

Greg Kroah-Hartman
2017-07-03T13:43:13Z

From: Igor Druzhinin <igor.druzhinin@citrix.com>

[ Upstream commit f16f1df65f1cf139ff9e9f84661e6573d6bb27fc ]

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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/xen-netback/interface.c | 6 ++++--
drivers/net/xen-netback/xenbus.c | 2 ++
2 files changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -221,18 +221,18 @@ static struct net_device_stats *xenvif_g
{
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_g
}

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;
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -503,9 +503,11 @@ static void backend_disconnect(struct ba
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);
}