From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: [net-next rfc V3 1/9] macvtap: fix a possible race between queue selection and changing queues Date: Wed, 5 Jun 2013 14:36:24 +0800 Message-ID: <1370414192-5830-2-git-send-email-jasowang@redhat.com> References: <1370414192-5830-1-git-send-email-jasowang@redhat.com> Cc: sergei.shtylyov@cogentembedded.com, Jason Wang To: davem@davemloft.net, mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Return-path: In-Reply-To: <1370414192-5830-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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. Signed-off-by: Jason Wang --- drivers/net/macvtap.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) 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) -- 1.7.1