On Wed, Feb 27, 2019 at 09:54:28AM +0100, Maxime Coquelin wrote:
> The vhost-user spec says that once the vring is disabled, the
> client has to stop processing it. But it can happen when
> dequeue zero-copy is enabled if outstanding descriptors buffers
> are still being processed by an extranl NIC or another guest.
s/extranl/external/
>
> The fix consists in draining the zmbufs list to ensure no more
> descriptors buffers are in the wild.
>
> Note that this fix is only working in the case REPLY_ACK
> protocol feature is enabled, which is not the case by default
> for now (it is only enabled when IOMMU feature is enabled in
> the vhost library).
>
> Fixes: b0a985d1f340 ("vhost: add dequeue zero copy")
> Cc: sta...@dpdk.org
>
> Signed-off-by: Maxime Coquelin <maxime.coque...@redhat.com>
> ---
> lib/librte_vhost/vhost_user.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index 36c0c676d..ef947b90c 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -1336,6 +1336,10 @@ vhost_user_set_vring_enable(struct virtio_net **pdev,
> "set queue enable: %d to qp idx: %d\n",
> enable, index);
>
> + /* On disable, rings have to be stopped being processed. */
> + if (!enable && dev->dequeue_zero_copy)
> + drain_zmbuf_list(dev->virtqueue[index]);
It might be better to drain the zmbufs list after calling
application's vring_state_changed() callback, so there will
be a chance for applications to take some actions first if
they want.
Overall this looks good to me,
Reviewed-by: Tiwei Bie <tiwei....@intel.com>
Thanks!
Tiwei
