Commit 119d5897 authored by Sasha Levin's avatar Sasha Levin Committed by Ben Hutchings

virtio_pci: defer kfree until release callback

commit 63bd62a0 upstream.

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.
Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
parent ddabe0f7
...@@ -612,11 +612,10 @@ static struct virtio_config_ops virtio_pci_config_ops = { ...@@ -612,11 +612,10 @@ static struct virtio_config_ops virtio_pci_config_ops = {
static void virtio_pci_release_dev(struct device *_d) static void virtio_pci_release_dev(struct device *_d)
{ {
/* struct virtio_device *vdev = dev_to_virtio(_d);
* No need for a release method as we allocate/free struct virtio_pci_device *vp_dev = to_vp_device(vdev);
* all devices together with the pci devices.
* Provide an empty one to avoid getting a warning from core. kfree(vp_dev);
*/
} }
/* the PCI probing function */ /* the PCI probing function */
...@@ -704,7 +703,6 @@ static void __devexit virtio_pci_remove(struct pci_dev *pci_dev) ...@@ -704,7 +703,6 @@ static void __devexit virtio_pci_remove(struct pci_dev *pci_dev)
pci_iounmap(pci_dev, vp_dev->ioaddr); pci_iounmap(pci_dev, vp_dev->ioaddr);
pci_release_regions(pci_dev); pci_release_regions(pci_dev);
pci_disable_device(pci_dev); pci_disable_device(pci_dev);
kfree(vp_dev);
} }
#ifdef CONFIG_PM #ifdef CONFIG_PM
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment