Re: [RFC PATCH v1 03/12] vsock: check for MSG_ZEROCOPY support

[Stefano Garzarella]

On Mon, Feb 06, 2023 at 06:55:46AM +0000, Arseniy Krasnov wrote:
> This feature totally depends on transport, so if transport doesn't
> support it, return error.
>
> Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx>
> ---
> include/net/af_vsock.h   | 2 ++
> net/vmw_vsock/af_vsock.c | 7 +++++++
> 2 files changed, 9 insertions(+)
>
> diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
> index 568a87c5e0d0..96d829004c81 100644
> --- a/include/net/af_vsock.h
> +++ b/include/net/af_vsock.h
> @@ -173,6 +173,8 @@ struct vsock_transport {
>
> 	/* Addressing. */
> 	u32 (*get_local_cid)(void);
> +

LGTM, just add comment here for a new section following what we did for
other callaback, e.g.:

        /* Zero-copy. */
> +	bool (*msgzerocopy_allow)(void);
> };
>
> /**** CORE ****/
> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> index f752b30b71d6..fb0fcb390113 100644
> --- a/net/vmw_vsock/af_vsock.c
> +++ b/net/vmw_vsock/af_vsock.c
> @@ -1788,6 +1788,13 @@ static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
> 		goto out;
> 	}
>
> +	if (msg->msg_flags & MSG_ZEROCOPY &&
> +	    (!transport->msgzerocopy_allow ||
> +	     !transport->msgzerocopy_allow())) {
> +		err = -EOPNOTSUPP;
> +		goto out;
> +	}
> +
> 	/* Wait for room in the produce queue to enqueue our user's data. */
> 	timeout = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
>
> --
> 2.25.1