RE: [PATCH 1/1] Drivers: hv: vmbus: Fix rescind handling issues

[KY Srinivasan]

> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuznets@xxxxxxxxxx]
> Sent: Friday, September 15, 2017 6:49 AM
> To: KY Srinivasan <kys@xxxxxxxxxxxxx>
> Cc: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx>; olaf@xxxxxxxxx;
> Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>;
> gregkh@xxxxxxxxxxxxxxxxxxx; jasowang@xxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; apw@xxxxxxxxxxxxx; marcelo.cerri@xxxxxxxxxxxxx;
> devel@xxxxxxxxxxxxxxxxxxxxxx; leann.ogasawara@xxxxxxxxxxxxx; Haiyang
> Zhang <haiyangz@xxxxxxxxxxxxx>
> Subject: Re: [PATCH 1/1] Drivers: hv: vmbus: Fix rescind handling issues
> 
> Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> writes:
> 
> > Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx> writes:
> >
> >> On Fri, 11 Aug 2017 10:03:59 -0700
> >> kys@xxxxxxxxxxxxxxxxxxxxxx wrote:
> >>
> >>> From: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> >>>
> >>> This patch handles the following issues that were observed when we are
> >>> handling racing channel offer message and rescind message for the
> same
> >>> offer:
> >>>
> >>> 1. Since the host does not respond to messages on a rescinded channel,
> >>> in the current code, we could be indefinitely blocked on the
> vmbus_open() call.
> >>>
> >>> 2. When a rescinded channel is being closed, if there is a pending
> interrupt on the
> >>> channel, we could end up freeing the channel that the interrupt handler
> would run on.
> >>>
> >>> Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> >>> Reviewed-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
> >>> Tested-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
> >>
> >> This patch breaks re-initialization of the network device on MTU changes.
> >>
> >> Doing:
> >> 	# ip li set dev eth1 mtu 9000
> >>
> >> will hang in rndis_filter_add waiting for subchannel notification.
> >> This is likely because when the vmbus device is reopened the sub
> channels
> >> are not correctly created.  Not sure what is wrong with the patch, but my
> >> suspicion is that the close/rescind events are no longer being sent to the
> >> host.
> >
> > I'm seeing the same issue, reverting the offending
> >
> > commit 6f3d791f300618caf82a2be0c27456edd76d5164
> > Author: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> > Date:   Fri Aug 11 10:03:59 2017 -0700
> >
> >     Drivers: hv: vmbus: Fix rescind handling issues
> >
> > which made it upstream helps. Did you guys do some investigation here?
> > In case not I can take a look next week.
> 
> Sorry, I have to resend - K.Y.'s kys@xxxxxxxxxxxxxxxxxxxxxx doesn't
> accept mail from me :-(

I think this turned out to be a bug in netvsc - Stephen can elaborate. I think the fix
has been submitted upstream as well.

K. Y
> 
> --
>   Vitaly