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Date: Fri, 25 Jan 2019 13:43:03 +0100
From: Jens Freimann <jfreimann@redhat.com>
To: Ilya Maximets <i.maximets@samsung.com>
Cc: dev@dpdk.org, Maxime Coquelin <maxime.coquelin@redhat.com>,
 "Michael S . Tsirkin" <mst@redhat.com>, Tiwei Bie <tiwei.bie@intel.com>,
 Zhihong Wang <zhihong.wang@intel.com>, stable@dpdk.org
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 (mx1.redhat.com [10.5.110.28]); Fri, 25 Jan 2019 12:43:14 +0000 (UTC)
Subject: Re: [dpdk-dev] [PATCH 1/3] net/virtio: fix improper read barriers
 on packed Tx cleanup
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On Thu, Jan 24, 2019 at 07:59:00PM +0300, Ilya Maximets wrote:
>Read barrier must be implied between reading descriptor flags
>and descriptor id. Otherwise, in case of reordering, we could
>read wrong descriptor id.
>
>For the reference, similar barrier for split rings is the read
>barrier between VIRTQUEUE_NUSED (reading the used->idx) and
>the call to the virtio_xmit_cleanup().
>
>Additionally removed double update of 'used_idx'. It's enough
>to set it in the end of the loop.
>
>Fixes: 892dc798fa9c ("net/virtio: implement Tx path for packed queues")
>Cc: stable@dpdk.org
>
>Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
>---
> drivers/net/virtio/virtio_rxtx.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>

Reviewed-by: Jens Freimann <jfreimann@redhat.com>