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

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Date:   Fri, 15 Sep 2017 18:01:05 +0000
From:   KY Srinivasan <kys@...rosoft.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
CC:     Stephen Hemminger <stephen@...workplumber.org>,
        "olaf@...fle.de" <olaf@...fle.de>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "apw@...onical.com" <apw@...onical.com>,
        "marcelo.cerri@...onical.com" <marcelo.cerri@...onical.com>,
        "devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
        "leann.ogasawara@...onical.com" <leann.ogasawara@...onical.com>,
        "Haiyang Zhang" <haiyangz@...rosoft.com>
Subject: RE: [PATCH 1/1] Drivers: hv: vmbus: Fix rescind handling issues



> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuznets@...hat.com]
> Sent: Friday, September 15, 2017 6:49 AM
> To: KY Srinivasan <kys@...rosoft.com>
> Cc: Stephen Hemminger <stephen@...workplumber.org>; olaf@...fle.de;
> Stephen Hemminger <sthemmin@...rosoft.com>;
> gregkh@...uxfoundation.org; jasowang@...hat.com; linux-
> kernel@...r.kernel.org; apw@...onical.com; marcelo.cerri@...onical.com;
> devel@...uxdriverproject.org; leann.ogasawara@...onical.com; Haiyang
> Zhang <haiyangz@...rosoft.com>
> Subject: Re: [PATCH 1/1] Drivers: hv: vmbus: Fix rescind handling issues
> 
> Vitaly Kuznetsov <vkuznets@...hat.com> writes:
> 
> > Stephen Hemminger <stephen@...workplumber.org> writes:
> >
> >> On Fri, 11 Aug 2017 10:03:59 -0700
> >> kys@...hange.microsoft.com wrote:
> >>
> >>> From: K. Y. Srinivasan <kys@...rosoft.com>
> >>>
> >>> 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 Since the host does not respond to messages on a rescinded channel,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 When a rescinded channel is being closed, if there is a pending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@...rosoft.com>
> >>> Reviewed-by: Dexuan Cui <decui@...rosoft.com>
> >>> Tested-by: Dexuan Cui <decui@...rosoft.com>
> >>
> >> 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@...rosoft.com>
> > 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@...hange.microsoft.com 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