On Tue, Mar 22, 2022 at 09:36:14AM -0400, Michael S. Tsirkin wrote:
On Tue, Mar 22, 2022 at 11:38:23AM +0100, Stefano Garzarella wrote:
virtio spec requires drivers to set DRIVER_OK before using VQs.
This is set automatically after probe returns, but virtio-vsock
driver uses VQs in the probe function to fill rx and event VQs
with new buffers.
So this is a spec violation. absolutely.
Let's fix this, calling virtio_device_ready() before using VQs
in the probe function.
Fixes: 0ea9e1d3a9e3 ("VSOCK: Introduce virtio_transport.ko")
Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
---
net/vmw_vsock/virtio_transport.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index 5afc194a58bb..b1962f8cd502 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -622,6 +622,8 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
INIT_WORK(&vsock->event_work, virtio_transport_event_work);
INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);
+ virtio_device_ready(vdev);
+
mutex_lock(&vsock->tx_lock);
vsock->tx_run = true;
mutex_unlock(&vsock->tx_lock);
Here's the whole code snippet:
mutex_lock(&vsock->tx_lock);
vsock->tx_run = true;
mutex_unlock(&vsock->tx_lock);
mutex_lock(&vsock->rx_lock);
virtio_vsock_rx_fill(vsock);
vsock->rx_run = true;
mutex_unlock(&vsock->rx_lock);
mutex_lock(&vsock->event_lock);
virtio_vsock_event_fill(vsock);
vsock->event_run = true;
mutex_unlock(&vsock->event_lock);
if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_SEQPACKET))
vsock->seqpacket_allow = true;
vdev->priv = vsock;
rcu_assign_pointer(the_virtio_vsock, vsock);
mutex_unlock(&the_virtio_vsock_mutex);
I worry that this is not the only problem here:
seqpacket_allow and setting of vdev->priv at least after
device is active look suspicious.
Right, so if you agree I'll move these before virtio_device_ready().
E.g.:
static void virtio_vsock_event_done(struct virtqueue *vq)
{
struct virtio_vsock *vsock = vq->vdev->priv;
if (!vsock)
return;
queue_work(virtio_vsock_workqueue, &vsock->event_work);
}
looks like it will miss events now they will be reported earlier.
One might say that since vq has been kicked it might send
interrupts earlier too so not a new problem, but
there's a chance device actually waits until DRIVER_OK
to start operating.
Yes I see, should I break into 2 patches (one where I move the code
already present and this one)?
Maybe a single patch is fine since it's the complete solution.
Thank you for the detailed explanation,
Stefano
