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From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: kys@exchange.microsoft.com,
        Stephen Hemminger <stephen@networkplumber.org>
Cc: Haiyang Zhang <haiyangz@microsoft.com>, olaf@aepfle.de,
        sthemmin@microsoft.com, gregkh@linuxfoundation.org,
        jasowang@redhat.com, linux-kernel@vger.kernel.org,
        marcelo.cerri@canonical.com, apw@canonical.com,
        devel@linuxdriverproject.org, leann.ogasawara@canonical.com
Subject: Re: [PATCH 1/1] Drivers: hv: vmbus: Fix rescind handling issues
References: <1502471039-5281-1-git-send-email-kys@exchange.microsoft.com>
        <20170824154102.62a02190@xeon-e3>
Date: Fri, 15 Sep 2017 15:42:10 +0200
In-Reply-To: <20170824154102.62a02190@xeon-e3> (Stephen Hemminger's message of
        "Thu, 24 Aug 2017 15:41:02 -0700")
Message-ID: <87ingkulhp.fsf@vitty.brq.redhat.com>
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Stephen Hemminger <stephen@networkplumber.org> writes:

> On Fri, 11 Aug 2017 10:03:59 -0700
> kys@exchange.microsoft.com wrote:
>
>> From: K. Y. Srinivasan <kys@microsoft.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 Since the host does not respond to messages on a rescinded channel,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 When a rescinded channel is being closed, if there is a pending interrupt on the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@microsoft.com>
>> Reviewed-by: Dexuan Cui <decui@microsoft.com>
>> Tested-by: Dexuan Cui <decui@microsoft.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@microsoft.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.

-- 
  Vitaly