From 2e0210432d34bc7f01644905c2bb2d5d9be5b6ac Mon Sep 17 00:00:00 2001 From: Heinz Graalfs Date: Thu, 27 Feb 2014 14:34:35 +0100 Subject: [PATCH] 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 Acked-by: Cornelia Huck Signed-off-by: Christian Borntraeger --- drivers/s390/kvm/virtio_ccw.c | 35 ++++++++++++++++++++++++++++------- 1 file changed, 28 insertions(+), 7 deletions(-) diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c index 0fc584832001..413c6304d511 100644 --- a/drivers/s390/kvm/virtio_ccw.c +++ b/drivers/s390/kvm/virtio_ccw.c @@ -636,6 +636,8 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev, 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 @@ static int virtio_ccw_probe(struct ccw_device *cdev) 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 @@ static int virtio_ccw_online(struct ccw_device *cdev) { int ret; struct virtio_ccw_device *vcdev; + unsigned long flags; vcdev = kzalloc(sizeof(*vcdev), GFP_KERNEL); if (!vcdev) { @@ -786,7 +803,9 @@ static int virtio_ccw_online(struct ccw_device *cdev) 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 @@ static int virtio_ccw_online(struct ccw_device *cdev) } 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: -- 2.20.1