From: Jiang Liu <liuj97@gmail.com>
Date: Fri, 7 Dec 2012 20:43:50 +0000 (-0700)
Subject: VFIO: use ACCESS_ONCE() to guard access to dev->driver
X-Git-Tag: firefly_0821_release~3680^2~1351^2~2
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=de2b3eeafb555d7b623c9f34e399b39105ca527f;p=firefly-linux-kernel-4.4.55.git

VFIO: use ACCESS_ONCE() to guard access to dev->driver

Comments from dev_driver_string(),
/* dev->driver can change to NULL underneath us because of unbinding,
 * so be careful about accessing it.
 */

So use ACCESS_ONCE() to guard access to dev->driver field.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 3b7fa7967221..12c264d3b058 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -465,8 +465,9 @@ static int vfio_dev_viable(struct device *dev, void *data)
 {
 	struct vfio_group *group = data;
 	struct vfio_device *device;
+	struct device_driver *drv = ACCESS_ONCE(dev->driver);
 
-	if (!dev->driver || vfio_whitelisted_driver(dev->driver))
+	if (!drv || vfio_whitelisted_driver(drv))
 		return 0;
 
 	device = vfio_group_get_device(group, dev);