From: Jason Wang Date: Wed, 5 Jun 2013 23:54:33 +0000 (+0000) Subject: macvtap: fix a possible race between queue selection and changing queues X-Git-Tag: v3.12-rc1~415^2~141 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ed0483fa06e0efb86a82e382a00dbad02b62807c;p=kernel%2Fkernel-generic.git 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 Signed-off-by: Jason Wang Signed-off-by: David S. Miller --- diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index 68efb91..5e485e3 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -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)