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Date:   Tue, 28 Mar 2023 11:29:12 +0200
From:   Stefano Garzarella <sgarzare@redhat.com>
To:     Arseniy Krasnov <avkrasnov@sberdevices.ru>
Cc:     Stefan Hajnoczi <stefanha@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Bobby Eshleman <bobby.eshleman@bytedance.com>,
        kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        kernel@sberdevices.ru, oxffffaa@gmail.com
Subject: Re: [RFC PATCH v2 2/3] virtio/vsock: WARN_ONCE() for invalid state
 of socket
Message-ID: <lgpswwclsuiukh2q5couf33jytf6abneazmwkty6fevoxcgh5p@3dzfbmenjhco>
References: <728181e9-6b35-0092-3d01-3d7aff4521b6@sberdevices.ru>
 <30aa2604-77c0-322e-44fd-ff99fc25e388@sberdevices.ru>
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In-Reply-To: <30aa2604-77c0-322e-44fd-ff99fc25e388@sberdevices.ru>
Precedence: bulk

On Sun, Mar 26, 2023 at 01:09:25AM +0300, Arseniy Krasnov wrote:
>This adds WARN_ONCE() and return from stream dequeue callback when
>socket's queue is empty, but 'rx_bytes' still non-zero.

Nit: I would explain why we add this, for example:

This allows the detection of potential bugs due to packet merging
(see previous patch).

>
>Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
>---
> net/vmw_vsock/virtio_transport_common.c | 7 +++++++
> 1 file changed, 7 insertions(+)

>
>diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>index b9144af71553..ad70531de133 100644
>--- a/net/vmw_vsock/virtio_transport_common.c
>+++ b/net/vmw_vsock/virtio_transport_common.c
>@@ -398,6 +398,13 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
> 	u32 free_space;
>
> 	spin_lock_bh(&vvs->rx_lock);
>+
>+	if (WARN_ONCE(skb_queue_empty(&vvs->rx_queue) && vvs->rx_bytes,
>+		      "No skbuffs with non-zero 'rx_bytes'\n")) {

Nit: I would rephrase it this way:
"rx_queue is empty, but rx_bytes is non-zero"

>+		spin_unlock_bh(&vvs->rx_lock);
>+		return err;
>+	}
>+
> 	while (total < len && !skb_queue_empty(&vvs->rx_queue)) {
> 		skb = skb_peek(&vvs->rx_queue);
>
>-- 
>2.25.1
>

Anyway the patch LGTM!

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