Re: [PATCH net-next v8 0/4] vsock/virtio/vhost: MSG_ZEROCOPY preparations

[Stefano Garzarella]

Hi Arseniy,

On Mon, Sep 11, 2023 at 11:22:30PM +0300, Arseniy Krasnov wrote:
> Hello,
>
> this patchset is first of three parts of another big patchset for
> MSG_ZEROCOPY flag support:
> https://lore.kernel.org/netdev/20230701063947.3422088-1-AVKrasnov@xxxxxxxxxxxxxx/
>
> During review of this series, Stefano Garzarella <sgarzare@xxxxxxxxxx>
> suggested to split it for three parts to simplify review and merging:
>
> 1) virtio and vhost updates (for fragged skbs) <--- this patchset
> 2) AF_VSOCK updates (allows to enable MSG_ZEROCOPY mode and read
>   tx completions) and update for Documentation/.
> 3) Updates for tests and utils.
>
> This series enables handling of fragged skbs in virtio and vhost parts.
> Newly logic won't be triggered, because SO_ZEROCOPY options is still
> impossible to enable at this moment (next bunch of patches from big
> set above will enable it).
>
> I've included changelog to some patches anyway, because there were some
> comments during review of last big patchset from the link above.

Thanks, I left some comments on patch 4, the others LGTM.
Sorry to not having spotted them before, but moving
virtio_transport_alloc_skb() around the file, made the patch a little
confusing and difficult to review.

In addition, I started having failures of test 14 (server: host,
client: guest), so I looked better to see if there was anything wrong,
but it fails me even without this series applied.

It happens to me intermittently (~30%), does it happen to you?
Can you take a look at it?

host$ ./vsock_test --mode=server --control-port=12345 --peer-cid=4
...
14 - SOCK_STREAM virtio skb merge...expected recv(2) returns 8 bytes, got 3

guest$ ./vsock_test --mode=client --control-host=192.168.133.2 --control-port=12345 --peer-cid=2

Thanks,
Stefano