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To: Tiwei Bie <tiwei.bie@intel.com>, zhihong.wang@intel.com, dev@dpdk.org
Cc: mst@redhat.com, jasowang@redhat.com, stable@dpdk.org
References: <20181011130655.5485-1-tiwei.bie@intel.com>
From: Maxime Coquelin <maxime.coquelin@redhat.com>
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Date: Thu, 11 Oct 2018 15:17:14 +0200
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Subject: Re: [dpdk-stable] [PATCH] vhost: fix notification for packed ring
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On 10/11/2018 03:06 PM, Tiwei Bie wrote:
> The notification can't be disabled in packed ring when
> application tries to disable notification, because the
> device event flags field is overwritten by an unexpected
> value. This patch fixes this issue.
> 
> Fixes: b1cce26af1dc ("vhost: add notification for packed ring")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
> ---
>   lib/librte_vhost/vhost.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
> index e62f4c594..c9270bdec 100644
> --- a/lib/librte_vhost/vhost.c
> +++ b/lib/librte_vhost/vhost.c
> @@ -667,8 +667,10 @@ vhost_enable_notify_packed(struct virtio_net *dev,
>   {
>   	uint16_t flags;
>   
> -	if (!enable)
> -		vq->device_event->flags = VRING_EVENT_F_DISABLE;
> +	if (!enable) {
> +		flags = VRING_EVENT_F_DISABLE;
> +		goto out;
> +	}
>   
>   	flags = VRING_EVENT_F_ENABLE;
>   	if (dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX)) {
> @@ -677,6 +679,7 @@ vhost_enable_notify_packed(struct virtio_net *dev,
>   			vq->avail_wrap_counter << 15;
>   	}
>   
> +out:
>   	rte_smp_wmb();
>   
>   	vq->device_event->flags = flags;
> 

Thanks for spotting this:
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Maxime