[PATCH 3.13.y-ckt 028/103] virtio_pci: document why we defer kfree

Kamal Mostafa
2015-02-19T01:00:29Z

From: "Michael S. Tsirkin" <mst@redhat.com>

commit a1eb03f546d651a8f39c7d0692b1f7f5b4e7e3cd upstream.

The reason we defer kfree until release function is because it's a
general rule for kobjects: kfree of the reference counter itself is only
legal in the release function.

Previous patch didn't make this clear, document this in code.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
drivers/virtio/virtio_pci.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 8a430b2..6b35f925 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -673,6 +673,9 @@ static void virtio_pci_release_dev(struct device *_d)
struct virtio_device *vdev = dev_to_virtio(_d);
struct virtio_pci_device *vp_dev = to_vp_device(vdev);

+ /* As struct device is a kobject, it's not safe to
+ * free the memory (including the reference counter itself)
+ * until it's release callback. */
kfree(vp_dev);
}

--
1.9.1