Messages in this thread Patch in this message | | | Date | Sun, 4 Jan 2015 18:02:22 +0200 | From | "Michael S. Tsirkin" <> | Subject | [PATCH 2/3] virtio_pci: defer kfree until release callback |
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From: Sasha Levin <sasha.levin@oracle.com>
A struct device which has just been unregistered can live on past the point at which a driver decides to drop it's initial reference to the kobject gained on allocation.
This implies that when releasing a virtio device, we can't free a struct virtio_device until the underlying struct device has been released, which might not happen immediately on device_unregister().
Unfortunately, this is exactly what virtio pci does: it has an empty release callback, and frees memory immediately after unregistering the device.
This causes an easy to reproduce crash if CONFIG_DEBUG_KOBJECT_RELEASE it enabled.
To fix, free the memory only once we know the device is gone in the release callback.
Cc: stable@vger.kernel.org Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- drivers/virtio/virtio_pci_legacy.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c index 08d1915..4beaee3 100644 --- a/drivers/virtio/virtio_pci_legacy.c +++ b/drivers/virtio/virtio_pci_legacy.c @@ -213,11 +213,10 @@ static const struct virtio_config_ops virtio_pci_config_ops = { static void virtio_pci_release_dev(struct device *_d) { - /* - * No need for a release method as we allocate/free - * all devices together with the pci devices. - * Provide an empty one to avoid getting a warning from core. - */ + struct virtio_device *vdev = dev_to_virtio(_d); + struct virtio_pci_device *vp_dev = to_vp_device(vdev); + + kfree(vp_dev); } /* the PCI probing function */ @@ -311,5 +310,4 @@ void virtio_pci_legacy_remove(struct pci_dev *pci_dev) pci_iounmap(pci_dev, vp_dev->ioaddr); pci_release_regions(pci_dev); pci_disable_device(pci_dev); - kfree(vp_dev); } -- MST
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