From e014e9444aedc365742d533e1443b22470cc67b9 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Thu, 14 Feb 2013 14:02:13 -0700 Subject: [PATCH] vfio: Protect vfio_dev_present against device_del vfio_dev_present is meant to give us a wait_event callback so that we can block removing a device from vfio until it becomes unused. The root of this check depends on being able to get the iommu group from the device. Unfortunately if the BUS_NOTIFY_DEL_DEVICE notifier has fired then the device-group reference is no longer searchable and we fail the lookup. We don't need to go to such extents for this though. We have a reference to the device, from which we can acquire a reference to the group. We can then use the group reference to search for the device and properly block removal. Signed-off-by: Alex Williamson --- drivers/vfio/vfio.c | 33 ++++++++++++--------------------- 1 file changed, 12 insertions(+), 21 deletions(-) diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 12c264d3b058..8e6dcecbc407 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -642,33 +642,16 @@ int vfio_add_group_dev(struct device *dev, } EXPORT_SYMBOL_GPL(vfio_add_group_dev); -/* Test whether a struct device is present in our tracking */ -static bool vfio_dev_present(struct device *dev) +/* Given a referenced group, check if it contains the device */ +static bool vfio_dev_present(struct vfio_group *group, struct device *dev) { - struct iommu_group *iommu_group; - struct vfio_group *group; struct vfio_device *device; - iommu_group = iommu_group_get(dev); - if (!iommu_group) - return false; - - group = vfio_group_get_from_iommu(iommu_group); - if (!group) { - iommu_group_put(iommu_group); - return false; - } - device = vfio_group_get_device(group, dev); - if (!device) { - vfio_group_put(group); - iommu_group_put(iommu_group); + if (!device) return false; - } vfio_device_put(device); - vfio_group_put(group); - iommu_group_put(iommu_group); return true; } @@ -682,10 +665,18 @@ void *vfio_del_group_dev(struct device *dev) struct iommu_group *iommu_group = group->iommu_group; void *device_data = device->device_data; + /* + * The group exists so long as we have a device reference. Get + * a group reference and use it to scan for the device going away. + */ + vfio_group_get(group); + vfio_device_put(device); /* TODO send a signal to encourage this to be released */ - wait_event(vfio.release_q, !vfio_dev_present(dev)); + wait_event(vfio.release_q, !vfio_dev_present(group, dev)); + + vfio_group_put(group); iommu_group_put(iommu_group); -- 2.34.1