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

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Message-ID: <BY2PR0301MB07113EC0C4277FA01AE66B9DA03D0@BY2PR0301MB0711.namprd03.prod.outlook.com>
Date:	Tue, 3 Feb 2015 03:40:30 +0000
From:	KY Srinivasan <kys@...rosoft.com>
To:	Jason Wang <jasowang@...hat.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



> -----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
> >
> >>
> >>  Thanks
> >>
> >>
> >