Re: [dpdk-dev] [PATCH] drivers/net: update link status

[Tiwei Bie <tiwei.bie@intel.com>]

On Fri, Apr 13, 2018 at 10:53:55PM +0100, Ferruh Yigit wrote:
> On 4/10/2018 4:41 PM, Tiwei Bie wrote:
> > On Tue, Mar 13, 2018 at 06:05:34PM +0000, Ferruh Yigit wrote:
> >> Update link status related feature document items and minor updates in
> >> some link status related functions.
> >>
> >> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
> >> ---
> >>  doc/guides/nics/features/fm10k.ini      | 2 ++
> >>  doc/guides/nics/features/fm10k_vf.ini   | 2 ++
> >>  doc/guides/nics/features/i40e_vf.ini    | 1 +
> >>  doc/guides/nics/features/igb_vf.ini     | 1 +
> >>  doc/guides/nics/features/qede.ini       | 1 -
> >>  doc/guides/nics/features/qede_vf.ini    | 1 -
> >>  doc/guides/nics/features/vhost.ini      | 2 --
> >>  doc/guides/nics/features/virtio_vec.ini | 1 +
> >>  drivers/net/e1000/em_ethdev.c           | 2 +-
> >>  drivers/net/ena/ena_ethdev.c            | 2 +-
> >>  drivers/net/fm10k/fm10k_ethdev.c        | 6 ++----
> >>  drivers/net/i40e/i40e_ethdev_vf.c       | 2 +-
> >>  drivers/net/ixgbe/ixgbe_ethdev.c        | 2 +-
> >>  drivers/net/mlx4/mlx4_ethdev.c          | 2 +-
> >>  drivers/net/mlx5/mlx5_ethdev.c          | 2 +-
> >>  15 files changed, 15 insertions(+), 14 deletions(-)
> > [...]
> >> diff --git a/doc/guides/nics/features/vhost.ini b/doc/guides/nics/features/vhost.ini
> >> index dffd1f493..31302745a 100644
> >> --- a/doc/guides/nics/features/vhost.ini
> >> +++ b/doc/guides/nics/features/vhost.ini
> >> @@ -4,8 +4,6 @@
> >>  ; Refer to default.ini for the full list of available PMD features.
> >>  ;
> >>  [Features]
> >> -Link status          = Y
> >> -Link status event    = Y
> > 
> > I think vhost PMD supports above features.
> 
> I am not able to find where it is supported.
> 
> Some virtual PMDs report fixed link, with empty link_update() dev_ops, and they
> are not reported as supporting Link status, as far as I can see vhost also one
> of them.
> 
> And for Link status event, PMD needs to support LSC interrupts and should
> register interrupt handler for it, which I can't find for vhost.
> 
> I will send next version without updating above one, please point me where these
> support added if I missed them.

In drivers/net/vhost/rte_eth_vhost.c you could find below functions:

static int
new_device(int vid)
{
	......

	eth_dev->data->dev_link.link_status = ETH_LINK_UP;

	......

	_rte_eth_dev_callback_process(eth_dev, RTE_ETH_EVENT_INTR_LSC, NULL);

	......
}

static void
destroy_device(int vid)
{
	......

	eth_dev->data->dev_link.link_status = ETH_LINK_DOWN;

	......

	_rte_eth_dev_callback_process(eth_dev, RTE_ETH_EVENT_INTR_LSC, NULL);

	......
}

They are the callbacks for vhost library.

When a frontend (e.g. QEMU) is connected to this vhost backend
and the frontend virtio device becomes ready, new_device() will
be called by the vhost library, and the link status will be
updated to UP.

And when e.g. the connection is closed, destroy_device() will be
called by the vhost library, and the link status will be updated
to DOWN.

So vhost PMD reports meaningful link status and also generates
link status events.

Thanks