RE: [PATCH net,v3] hyperv: Fix the carrier status setting

[Haiyang Zhang <haiyangz@microsoft.com>]

> -----Original Message-----
> From: Jason Wang [mailto:jasowang@redhat.com]
> Sent: Wednesday, February 12, 2014 10:52 PM
> To: Haiyang Zhang; davem@davemloft.net; netdev@vger.kernel.org
> Cc: KY Srinivasan; olaf@aepfle.de; linux-kernel@vger.kernel.org; driverdev-
> devel@linuxdriverproject.org
> Subject: Re: [PATCH net,v3] hyperv: Fix the carrier status setting
> 
> On 02/13/2014 08:54 AM, Haiyang Zhang wrote:
> > Without this patch, the "cat /sys/class/net/ethN/operstate" shows
> > "unknown", and "ethtool ethN" shows "Link detected: yes", when VM
> > boots up with or without vNIC connected.
> >
> > This patch fixed the problem.
> >
> > Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> > Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
> > ---
> >  drivers/net/hyperv/netvsc_drv.c |   53
> ++++++++++++++++++++++++++++-----------
> >  1 files changed, 38 insertions(+), 15 deletions(-)
> >
> > diff --git a/drivers/net/hyperv/netvsc_drv.c
> > b/drivers/net/hyperv/netvsc_drv.c index 7756118..7141a19 100644
> > --- a/drivers/net/hyperv/netvsc_drv.c
> > +++ b/drivers/net/hyperv/netvsc_drv.c
> > @@ -88,8 +88,12 @@ static int netvsc_open(struct net_device *net)  {
> >  	struct net_device_context *net_device_ctx = netdev_priv(net);
> >  	struct hv_device *device_obj = net_device_ctx->device_ctx;
> > +	struct netvsc_device *nvdev;
> > +	struct rndis_device *rdev;
> >  	int ret = 0;
> >
> > +	netif_carrier_off(net);
> > +
> >  	/* Open up the device */
> >  	ret = rndis_filter_open(device_obj);
> >  	if (ret != 0) {
> > @@ -99,6 +103,11 @@ static int netvsc_open(struct net_device *net)
> >
> >  	netif_start_queue(net);
> >
> > +	nvdev = hv_get_drvdata(device_obj);
> > +	rdev = nvdev->extension;
> > +	if (!rdev->link_state)
> > +		netif_carrier_on(net);
> > +
> 
> Maybe you can just schedule the work here and then you can drop the
> rtnl_lock in netvsc_link_change() ?

The rtnl_lock will still be necessary in the netvsc_link_change(), because 
we want to prevent it getting wrong rdev pointer when netvsc_change_mtu
is removing/adding rndis device.

> > +
> > +	if (notify)
> > +		netdev_notify_peers(net);
> >  }
> >
> 
> Looks like this forces arp_notify here. Is it expected?

Yes, this is expected. It's required after live migration.

Thanks,
- Haiyang