RE: [PATCH 1/8] Drivers: hv: kvp: fix IP Failover

[KY Srinivasan]

> -----Original Message-----
> From: Greg KH [mailto:gregkh@xxxxxxxxxxxxxxxxxxx]
> Sent: Saturday, April 30, 2016 2:05 PM
> To: KY Srinivasan <kys@xxxxxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx;
> olaf@xxxxxxxxx; apw@xxxxxxxxxxxxx; vkuznets@xxxxxxxxxx;
> jasowang@xxxxxxxxxx
> Subject: Re: [PATCH 1/8] Drivers: hv: kvp: fix IP Failover
> 
> On Tue, Apr 05, 2016 at 04:57:40PM -0700, K. Y. Srinivasan wrote:
> > From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> >
> > Hyper-V VMs can be replicated to another hosts and there is a feature to
> > set different IP for replicas, it is called 'Failover TCP/IP'. When
> > such guest starts Hyper-V host sends it KVP_OP_SET_IP_INFO message as
> soon
> > as we finish negotiation procedure. The problem is that it can happen (and
> > it actually happens) before userspace daemon connects and we reply with
> > HV_E_FAIL to the message. As there are no repetitions we fail to set the
> > requested IP.
> >
> > Solve the issue by postponing our reply to the negotiation message till
> > userspace daemon is connected. We can't wait too long as there is a
> > host-side timeout (cca. 75 seconds) and if we fail to reply in this time
> > frame the whole KVP service will become inactive. The solution is not
> > ideal - if it takes userspace daemon more than 60 seconds to connect
> > IP Failover will still fail but I don't see a solution with our current
> > separation between kernel and userspace parts.
> >
> > Other two modules (VSS and FCOPY) don't require such delay, leave them
> > untouched.
> >
> > Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> > Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> > ---
> >  drivers/hv/hv_kvp.c       |   31 +++++++++++++++++++++++++++++++
> >  drivers/hv/hyperv_vmbus.h |    5 +++++
> >  2 files changed, 36 insertions(+), 0 deletions(-)
> 
> This series doesn't apply to my tree :(

Looks like you have already applied most of the patches in this series. I will resend what is not applied.

Thanks,

K. Y