Re: [RFC PATCH v5 08/17] vsock: check for MSG_ZEROCOPY support on send

[Stefano Garzarella <sgarzare@redhat.com>]

On Sat, Jul 01, 2023 at 09:39:38AM +0300, Arseniy Krasnov wrote:
>This feature totally depends on transport, so if transport doesn't
>support it, return error.
>
>Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
>---
> include/net/af_vsock.h   | 7 +++++++
> net/vmw_vsock/af_vsock.c | 6 ++++++
> 2 files changed, 13 insertions(+)

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

>
>diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
>index 0e7504a42925..ec09edc5f3a0 100644
>--- a/include/net/af_vsock.h
>+++ b/include/net/af_vsock.h
>@@ -177,6 +177,9 @@ struct vsock_transport {
>
> 	/* Read a single skb */
> 	int (*read_skb)(struct vsock_sock *, skb_read_actor_t);
>+
>+	/* Zero-copy. */
>+	bool (*msgzerocopy_allow)(void);
> };
>
> /**** CORE ****/
>@@ -243,4 +246,8 @@ static inline void __init vsock_bpf_build_proto(void)
> {}
> #endif
>
>+static inline bool vsock_msgzerocopy_allow(const struct vsock_transport *t)
>+{
>+	return t->msgzerocopy_allow && t->msgzerocopy_allow();
>+}
> #endif /* __AF_VSOCK_H__ */
>diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>index 07803d9fbf6d..033006e1b5ad 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -1824,6 +1824,12 @@ static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
> 		goto out;
> 	}
>
>+	if (msg->msg_flags & MSG_ZEROCOPY &&
>+	    !vsock_msgzerocopy_allow(transport)) {
>+		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
>