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From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: kys@microsoft.com
Cc: Stephen Hemminger <stephen@networkplumber.org>, olaf@aepfle.de,
        sthemmin@microsoft.com, gregkh@linuxfoundation.org,
        jasowang@redhat.com, linux-kernel@vger.kernel.org, apw@canonical.com,
        marcelo.cerri@canonical.com, devel@linuxdriverproject.org,
        leann.ogasawara@canonical.com, Haiyang Zhang <haiyangz@microsoft.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>
        <87ingkulhp.fsf@vitty.brq.redhat.com>
Date: Fri, 15 Sep 2017 15:48:34 +0200
In-Reply-To: <87ingkulhp.fsf@vitty.brq.redhat.com> (Vitaly Kuznetsov's message
        of "Fri, 15 Sep 2017 15:42:10 +0200")
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Vitaly Kuznetsov <vkuznets@redhat.com> writes:

> 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 Since the host does not respond to messages on a rescinded channel,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 When a rescinded channel is being closed, if there is a pending interrupt on the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.

Sorry, I have to resend - K.Y.'s kys@exchange.microsoft.com doesn't
accept mail from me :-(

-- 
  Vitaly