virtio_ccw: fix vcdev pointer handling issues
The interrupt handler virtio_ccw_int_handler() using the vcdev pointer
is protected by the ccw_device lock. Resetting the pointer within the
ccw_device structure should be done when holding this lock.
Also resetting the vcdev pointer (under the ccw_device lock) prior to
freeing the vcdev pointer memory removes a critical path.
Signed-off-by: Heinz Graalfs <graalfs@linux.vnet.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
index 0fc5848..413c630 100644
--- a/drivers/s390/kvm/virtio_ccw.c
+++ b/drivers/s390/kvm/virtio_ccw.c
@@ -636,6 +636,8 @@
struct virtqueue *vq;
struct virtio_driver *drv;
+ if (!vcdev)
+ return;
/* Check if it's a notification from the host. */
if ((intparm == 0) &&
(scsw_stctl(&irb->scsw) ==
@@ -734,23 +736,37 @@
return 0;
}
+static struct virtio_ccw_device *virtio_grab_drvdata(struct ccw_device *cdev)
+{
+ unsigned long flags;
+ struct virtio_ccw_device *vcdev;
+
+ spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
+ vcdev = dev_get_drvdata(&cdev->dev);
+ if (!vcdev) {
+ spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
+ return NULL;
+ }
+ dev_set_drvdata(&cdev->dev, NULL);
+ spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
+ return vcdev;
+}
+
static void virtio_ccw_remove(struct ccw_device *cdev)
{
- struct virtio_ccw_device *vcdev = dev_get_drvdata(&cdev->dev);
+ struct virtio_ccw_device *vcdev = virtio_grab_drvdata(cdev);
- if (cdev->online) {
+ if (vcdev && cdev->online)
unregister_virtio_device(&vcdev->vdev);
- dev_set_drvdata(&cdev->dev, NULL);
- }
cdev->handler = NULL;
}
static int virtio_ccw_offline(struct ccw_device *cdev)
{
- struct virtio_ccw_device *vcdev = dev_get_drvdata(&cdev->dev);
+ struct virtio_ccw_device *vcdev = virtio_grab_drvdata(cdev);
- unregister_virtio_device(&vcdev->vdev);
- dev_set_drvdata(&cdev->dev, NULL);
+ if (vcdev)
+ unregister_virtio_device(&vcdev->vdev);
return 0;
}
@@ -759,6 +775,7 @@
{
int ret;
struct virtio_ccw_device *vcdev;
+ unsigned long flags;
vcdev = kzalloc(sizeof(*vcdev), GFP_KERNEL);
if (!vcdev) {
@@ -786,7 +803,9 @@
INIT_LIST_HEAD(&vcdev->virtqueues);
spin_lock_init(&vcdev->lock);
+ spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
dev_set_drvdata(&cdev->dev, vcdev);
+ spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
vcdev->vdev.id.vendor = cdev->id.cu_type;
vcdev->vdev.id.device = cdev->id.cu_model;
ret = register_virtio_device(&vcdev->vdev);
@@ -797,7 +816,9 @@
}
return 0;
out_put:
+ spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
dev_set_drvdata(&cdev->dev, NULL);
+ spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
put_device(&vcdev->vdev.dev);
return ret;
out_free: