diff options
Diffstat (limited to 'drivers/vfio/vfio.c')
| -rw-r--r-- | drivers/vfio/vfio.c | 27 |
1 files changed, 19 insertions, 8 deletions
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index e1278fe04b1e..2fb29dfeffbd 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -661,18 +661,29 @@ int vfio_add_group_dev(struct device *dev, EXPORT_SYMBOL_GPL(vfio_add_group_dev); /** - * Get a reference to the vfio_device for a device that is known to - * be bound to a vfio driver. The driver implicitly holds a - * vfio_device reference between vfio_add_group_dev and - * vfio_del_group_dev. We can therefore use drvdata to increment - * that reference from the struct device. This additional - * reference must be released by calling vfio_device_put. + * Get a reference to the vfio_device for a device. Even if the + * caller thinks they own the device, they could be racing with a + * release call path, so we can't trust drvdata for the shortcut. + * Go the long way around, from the iommu_group to the vfio_group + * to the vfio_device. */ struct vfio_device *vfio_device_get_from_dev(struct device *dev) { - struct vfio_device *device = dev_get_drvdata(dev); + struct iommu_group *iommu_group; + struct vfio_group *group; + struct vfio_device *device; + + iommu_group = iommu_group_get(dev); + if (!iommu_group) + return NULL; - vfio_device_get(device); + group = vfio_group_get_from_iommu(iommu_group); + iommu_group_put(iommu_group); + if (!group) + return NULL; + + device = vfio_group_get_device(group, dev); + vfio_group_put(group); return device; } |