linux-kernel - Re: [PATCH net-next v3 1/3] vsock: Add support for SIOCINQ ioctl

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Message-ID: <y465uw5phymt3gbgdxsxlopeyhcbbherjri6b6etl64qhsc4ud@vc2c45mo5zxw>
Date: Tue, 17 Jun 2025 16:39:25 +0200
From: Stefano Garzarella <sgarzare@...hat.com>
To: Xuewei Niu <niuxuewei97@...il.com>, 
	"K. Y. Srinivasan" <kys@...rosoft.com>, Haiyang Zhang <haiyangz@...rosoft.com>, 
	Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>, linux-hyperv@...r.kernel.org
Cc: mst@...hat.com, pabeni@...hat.com, jasowang@...hat.com, 
	xuanzhuo@...ux.alibaba.com, davem@...emloft.net, netdev@...r.kernel.org, stefanha@...hat.com, 
	leonardi@...hat.com, virtualization@...ts.linux.dev, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, fupan.lfp@...group.com, Xuewei Niu <niuxuewei.nxw@...group.com>
Subject: Re: [PATCH net-next v3 1/3] vsock: Add support for SIOCINQ ioctl

CCin hyper-v maintainers and list since I have a question about hyperv 
transport.

On Tue, Jun 17, 2025 at 12:53:44PM +0800, Xuewei Niu wrote:
>Add support for SIOCINQ ioctl, indicating the length of bytes unread in the
>socket. The value is obtained from `vsock_stream_has_data()`.
>
>Signed-off-by: Xuewei Niu <niuxuewei.nxw@...group.com>
>---
> net/vmw_vsock/af_vsock.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
>diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>index 2e7a3034e965..bae6b89bb5fb 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -1389,6 +1389,28 @@ static int vsock_do_ioctl(struct socket *sock, unsigned int cmd,
> 	vsk = vsock_sk(sk);
>
> 	switch (cmd) {
>+	case SIOCINQ: {
>+		ssize_t n_bytes;
>+
>+		if (!vsk->transport) {
>+			ret = -EOPNOTSUPP;
>+			break;
>+		}
>+
>+		if (sock_type_connectible(sk->sk_type) &&
>+		    sk->sk_state == TCP_LISTEN) {
>+			ret = -EINVAL;
>+			break;
>+		}
>+
>+		n_bytes = vsock_stream_has_data(vsk);

Now looks better to me, I just checked transports: vmci and virtio/vhost 
returns what we want, but for hyperv we have:

	static s64 hvs_stream_has_data(struct vsock_sock *vsk)
	{
		struct hvsock *hvs = vsk->trans;
		s64 ret;

		if (hvs->recv_data_len > 0)
			return 1;

@Hyper-v maintainers: do you know why we don't return `recv_data_len`?
Do you think we can do that to support this new feature?

Thanks,
Stefano

>+		if (n_bytes < 0) {
>+			ret = n_bytes;
>+			break;
>+		}
>+		ret = put_user(n_bytes, arg);
>+		break;
>+	}
> 	case SIOCOUTQ: {
> 		ssize_t n_bytes;
>
>-- 
>2.34.1
>