linux-kernel - RE: [PATCH v2 1/3] hv: hv_util: move vmbus

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Message-Id: <1422938128.6732.3@smtp.corp.redhat.com>
Date:	Tue, 03 Feb 2015 04:43:28 +0008
From:	Jason Wang <jasowang@...hat.com>
To:	KY Srinivasan <kys@...rosoft.com>
Cc:	Dexuan Cui <decui@...rosoft.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"driverdev-devel@...uxdriverproject.org" 
	<driverdev-devel@...uxdriverproject.org>,
	"olaf@...fle.de" <olaf@...fle.de>,
	"apw@...onical.com" <apw@...onical.com>,
	"vkuznets@...hat.com" <vkuznets@...hat.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>
Subject: RE: [PATCH v2 1/3] hv: hv_util: move vmbus_open() to a later place



On Tue, Feb 3, 2015 at 11:40 AM, KY Srinivasan <kys@...rosoft.com> 
wrote:
> 
> 
>>  -----Original Message-----
>>  From: Jason Wang [mailto:jasowang@...hat.com]
>>  Sent: Monday, February 2, 2015 7:38 PM
>>  To: KY Srinivasan
>>  Cc: Dexuan Cui; gregkh@...uxfoundation.org; 
>> linux-kernel@...r.kernel.org;
>>  driverdev-devel@...uxdriverproject.org; olaf@...fle.de;
>>  apw@...onical.com; vkuznets@...hat.com; Haiyang Zhang
>>  Subject: RE: [PATCH v2 1/3] hv: hv_util: move vmbus_open() to a 
>> later place
>>  
>>  
>>  
>>  On Tue, Feb 3, 2015 at 11:30 AM, KY Srinivasan <kys@...rosoft.com>
>>  wrote:
>>  >
>>  >
>>  >>  -----Original Message-----
>>  >>  From: Jason Wang [mailto:jasowang@...hat.com]
>>  >>  Sent: Monday, February 2, 2015 7:09 PM
>>  >>  To: Dexuan Cui
>>  >>  Cc: gregkh@...uxfoundation.org; linux-kernel@...r.kernel.org;
>>  >> driverdev-
>>  >>  devel@...uxdriverproject.org; olaf@...fle.de; 
>> apw@...onical.com; KY
>>  >> Srinivasan; vkuznets@...hat.com; Haiyang Zhang
>>  >>  Subject: RE: [PATCH v2 1/3] hv: hv_util: move vmbus_open() to a
>>  >> later place
>>  >>
>>  >>
>>  >>
>>  >>  On Mon, Feb 2, 2015 at 6:09 PM, Dexuan Cui <decui@...rosoft.com>
>>  >> wrote:
>>  >>  >>  -----Original Message-----
>>  >>  >>  From: Jason Wang [mailto:jasowang@...hat.com]  >>  Sent: 
>> Monday,
>>  >> February 2, 2015 17:36 PM  >>  To: Dexuan Cui  >>  Cc:
>>  >> gregkh@...uxfoundation.org; linux-kernel@...r.kernel.org;  >>
>>  >> driverdev-  >>  devel@...uxdriverproject.org; olaf@...fle.de;
>>  >> apw@...onical.com; KY  >> Srinivasan; vkuznets@...hat.com; 
>> Haiyang
>>  >> Zhang  >>  Subject: Re: [PATCH v2 1/3] hv: hv_util: move 
>> vmbus_open()
>>  >> to a  >> later place  >>  >>  >>  >>  On Mon, Feb 2, 2015 at 
>> 12:35
>>  >> PM, Dexuan Cui <decui@...rosoft.com>  >> wrote:
>>  >>  >>  > Before the line vmbus_open() returns, srv->util_cb can be
>>  >> already  >> > running  > and the variables, like 
>> util_fw_version, are
>>  >> needed by  >> the  > srv->util_cb.
>>  >>  >>
>>  >>  >>  A questions is why we do this for util only? Can callbacks 
>> of
>>  >> other  >> devices be called before vmbus_open() returns?
>>  >>  > The variables are used in vmbus_prep_negotiate_resp(), which 
>> is
>>  >> only  > for the util devices.
>>  >>  >
>>  >>  > I think the other devices should already handle the similar 
>> issue
>>  >> > properly.
>>  >>  > If this is not the case, we need to fix them too.
>>  >>
>>  >>  Better to check all the others, e.g in balloon_probe(), it call
>>  >>  hv_set_drvdata() after vmbus_open() and dose several datas 
>> setups in
>>  >> the  middle. If balloon_onchannelcallback() could be called 
>> before
>>  >> hv_set_drvdata(), the code looks wrong.
>>  >
>>  > Jason,
>>  >
>>  > For all other device types, the guest initiates the communication 
>> with
>>  > the host and potentially negotiates appropriate (supported) 
>> version
>>  > with the host. For the services packaged in the util driver, the 
>> flow
>>  > is a little different - the host pushes the version information 
>> into
>>  > the guest. So, the fix Dexuan made is only needed in the util 
>> driver.
>>  >
>>  > Regards,
>>  >
>>  > K. Y
>>  
>>  Thanks, so you mean for other device, it won't get any interrupt 
>> before guest
>>  negotiate the version with host?
> 
> Yes, the guest initiates the version negotiation. Are you seeing 
> something different?
> 
> K. Y

No, thanks.

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