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macvtap: fix a possible race between queue selection and changing queues 

Complier may generate codes that re-read the vlan->numvtaps during
macvtap_get_queue(). This may lead a race if vlan->numvtaps were changed in the
same time and which can lead unexpected result (e.g. very huge value).

We need prevent the compiler from generating such codes by adding an
ACCESS_ONCE() to make sure vlan->numvtaps were only read once.

Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason Wang 2013-06-05 23:54:33 +00:00 committed by David S. Miller
parent e403d29581
commit ed0483fa06
1 changed files with 1 additions and 1 deletions
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2
drivers/net/macvtap.c
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@ -172,7 +172,7 @@ static struct macvtap_queue *macvtap_get_queue(struct net_device *dev,
{
struct macvlan_dev *vlan = netdev_priv(dev);
struct macvtap_queue *tap = NULL;
int numvtaps = vlan->numvtaps;
int numvtaps = ACCESS_ONCE(vlan->numvtaps);
__u32 rxq;
if (!numvtaps)