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    Subject[PATCH 3.16.y-ckt 58/58] virtio_pci: document why we defer kfree
    Date
    3.16.7-ckt7 -stable review patch.  If anyone has any objections, please let me know.

    ------------------

    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>
    [ luis: backported to 3.16:
    - file rename: virtio_pci_legacy.c -> virtio_pci.c ]
    Signed-off-by: Luis Henriques <luis.henriques@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 a46570005a98..52c4607fec9e 100644
    --- a/drivers/virtio/virtio_pci.c
    +++ b/drivers/virtio/virtio_pci.c
    @@ -671,6 +671,9 @@ 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);
    }

    --
    2.1.4


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