Re: [dpdk-dev] [PATCH] vhost: fix wait for valid descriptor

["Tan, Jianfeng" <jianfeng.tan@intel.com>]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Tomasz Kulasek
> Sent: Saturday, February 10, 2018 1:35 AM
> To: yliu@fridaylinux.org
> Cc: dev@dpdk.org; yuanhan.liu@linux.intel.com; stable@dpdk.org; Liu,
> Changpeng
> Subject: [dpdk-dev] [PATCH] vhost: fix wait for valid descriptor
> 
> For each virt queue's kickfd and callfd, there are 2 invalid
> status: VIRTIO_UNINITIALIZED_EVENTFD and VIRTIO_INVALID_EVENTFD.
> Don't set the virt queue to ready status until got the valid
> descriptor.

Cannot remember why we introduce two invalid status.

If we treat "VIRTIO_INVALID_EVENTFD" as an indicator to judge if device is ready, then defining one status (invalid) is enough.

Thanks,
Jianfeng

> 
> This is safe for polling mode drivers in Guest OS, the backend
> vhost process will not post notification to interrupt vector for
> PMD mode in guest, but the interrupt vector still valid.
> 
> Fixes: e049ca6d10e0 ("vhost-user: prepare multiple queue setup")
> Cc: yuanhan.liu@linux.intel.com
> Cc: stable@dpdk.org
> 
> Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
> Signed-off-by: Tomasz Kulasek <tomaszx.kulasek@intel.com>
> ---
>  lib/librte_vhost/vhost_user.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index 65ee33919..4508f697b 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -766,7 +766,9 @@ vq_is_ready(struct vhost_virtqueue *vq)
>  {
>  	return vq && vq->desc && vq->avail && vq->used &&
>  	       vq->kickfd != VIRTIO_UNINITIALIZED_EVENTFD &&
> -	       vq->callfd != VIRTIO_UNINITIALIZED_EVENTFD;
> +	       vq->callfd != VIRTIO_UNINITIALIZED_EVENTFD &&
> +	       vq->kickfd != VIRTIO_INVALID_EVENTFD &&
> +	       vq->callfd != VIRTIO_INVALID_EVENTFD;
>  }
> 
>  static int
> --
> 2.14.1