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Date:   Tue, 21 Apr 2020 16:42:46 +0100
From:   Stefan Hajnoczi <stefanha@gmail.com>
To:     Stefano Garzarella <sgarzare@redhat.com>
Cc:     davem@davemloft.net, Gerard Garcia <ggarcia@abra.uab.cat>,
        kvm@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org,
        Stefan Hajnoczi <stefanha@redhat.com>,
        Jakub Kicinski <kuba@kernel.org>
Subject: Re: [PATCH net] vsock/virtio: postpone packet delivery to monitoring
 devices
Message-ID: <20200421154246.GA47385@stefanha-x1.localdomain>
References: <20200421092527.41651-1-sgarzare@redhat.com>
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On Tue, Apr 21, 2020 at 11:25:27AM +0200, Stefano Garzarella wrote:
> We delivering packets to monitoring devices, before to check if
> the virtqueue has enough space.

"We [are] delivering packets" and "before to check" -> "before
checking".  Perhaps it can be rewritten as:

  Packets are delivered to monitoring devices before checking if the
  virtqueue has enough space.

>=20
> If the virtqueue is full, the transmitting packet is queued up
> and it will be sent in the next iteration. This causes the same
> packet to be delivered multiple times to monitoring devices.
>=20
> This patch fixes this issue, postponing the packet delivery
> to monitoring devices, only when it is properly queued in the

s/,//

> virqueue.

s/virqueue/virtqueue/

> @@ -137,6 +135,11 @@ virtio_transport_send_pkt_work(struct work_struct *w=
ork)
>  			break;
>  		}
> =20
> +		/* Deliver to monitoring devices all correctly transmitted
> +		 * packets.
> +		 */
> +		virtio_transport_deliver_tap_pkt(pkt);
> +

The device may see the tx packet and therefore receive a reply to it
before we can call virtio_transport_deliver_tap_pkt().  Does this mean
that replies can now appear in the packet capture before the transmitted
packet?

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