linux-kernel - Re: [RFC PATCH v1 2/3] virtio/vsock: use 'target' in notify_poll

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Date:   Tue, 19 Jul 2022 14:48:57 +0200
From:   Stefano Garzarella <sgarzare@...hat.com>
To:     Arseniy Krasnov <AVKrasnov@...rdevices.ru>
Cc:     "David S. Miller" <davem@...emloft.net>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Krasnov Arseniy <oxffffaa@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        kernel <kernel@...rdevices.ru>
Subject: Re: [RFC PATCH v1 2/3] virtio/vsock: use 'target' in notify_poll_in,
 callback.

On Mon, Jul 18, 2022 at 08:17:31AM +0000, Arseniy Krasnov wrote:
>This callback controls setting of POLLIN,POLLRDNORM output bits
>of poll() syscall,but in some cases,it is incorrectly to set it,
>when socket has at least 1 bytes of available data. Use 'target'
>which is already exists and equal to sk_rcvlowat in this case.
>
>Signed-off-by: Arseniy Krasnov <AVKrasnov@...rdevices.ru>
>---
> net/vmw_vsock/virtio_transport_common.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>index ec2c2afbf0d0..591908740992 100644
>--- a/net/vmw_vsock/virtio_transport_common.c
>+++ b/net/vmw_vsock/virtio_transport_common.c
>@@ -634,7 +634,7 @@ virtio_transport_notify_poll_in(struct vsock_sock *vsk,
> 				size_t target,
> 				bool *data_ready_now)
> {
>-	if (vsock_stream_has_data(vsk))
>+	if (vsock_stream_has_data(vsk) >= target)
> 		*data_ready_now = true;
> 	else
> 		*data_ready_now = false;

Perhaps we can take the opportunity to clean up the code in this way:

	*data_ready_now = vsock_stream_has_data(vsk) >= target;

Anyway, I think we also need to fix the other transports (vmci and 
hyperv), what do you think?

Thanks,
Stefano