[PATCH] Bluetooth: virtio_bt: fix device removal

Michael S. Tsirkin
2021-11-25T17:46:57Z

Device removal is clearly out of virtio spec: it attempts to remove
unused buffers from a VQ before invoking device reset. To fix, make
open/close NOPs and do all cleanup/setup in probe/remove.

The cost here is a single skb wasted on an unused bt device - which
seems modest.

NB: with this fix in place driver still suffers from a race condition if
an interrupt triggers while device is being reset. Work on a fix for
that issue is in progress.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---

Note: completely untested, in particular the device isn't supported in QEMU.
Please do not queue directly - please help review and test and ack,
and I will queue this together with reset fixes.
Thanks!

drivers/bluetooth/virtio_bt.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c
index 24a9258962fa..aea33ba9522c 100644
--- a/drivers/bluetooth/virtio_bt.c
+++ b/drivers/bluetooth/virtio_bt.c
@@ -50,8 +50,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt)

static int virtbt_open(struct hci_dev *hdev)
{
- struct virtio_bluetooth *vbt = hci_get_drvdata(hdev);
+ return 0;
+}

+static int virtbt_open_vdev(struct virtio_bluetooth *vbt)
+{
if (virtbt_add_inbuf(vbt) < 0)
return -EIO;

@@ -61,7 +64,11 @@ static int virtbt_open(struct hci_dev *hdev)

static int virtbt_close(struct hci_dev *hdev)
{
- struct virtio_bluetooth *vbt = hci_get_drvdata(hdev);
+ return 0;
+}
+
+static int virtbt_close_vdev(struct virtio_bluetooth *vbt)
+{
int i;

cancel_work_sync(&vbt->rx);
@@ -351,8 +358,14 @@ static int virtbt_probe(struct virtio_device *vdev)
goto failed;
}

+ virtio_device_ready(vdev);
+ if (virtbt_open_vdev(vbt))
+ goto open_failed;
+
return 0;

+open_failed:
+ hci_free_dev(hdev);
failed:
vdev->config->del_vqs(vdev);
return err;
@@ -365,6 +378,7 @@ static void virtbt_remove(struct virtio_device *vdev)

hci_unregister_dev(hdev);
vdev->config->reset(vdev);
+ virtbt_close_vdev(vbt);

hci_free_dev(hdev);
vbt->hdev = NULL;
--
MST