linux-kernel - RE: [PATCH] hv: hv_fcopy: drop the obsolete message on transfer failure

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Message-ID: <F792CF86EFE20D4AB8064279AFBA51C613E6402E@HKNPRD3002MB017.064d.mgd.msft.net>
Date:	Thu, 27 Nov 2014 06:21:31 +0000
From:	Dexuan Cui <decui@...rosoft.com>
To:	Greg KH <gregkh@...uxfoundation.org>
CC:	"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>,
	"jasowang@...hat.com" <jasowang@...hat.com>,
	KY Srinivasan <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	"vkuznets@...hat.com" <vkuznets@...hat.com>
Subject: RE: [PATCH] hv: hv_fcopy: drop the obsolete message on transfer
 failure

> -----Original Message-----
> From: Greg KH [mailto:gregkh@...uxfoundation.org]
> Sent: Thursday, November 27, 2014 7:54 AM
> To: Dexuan Cui
> Cc: linux-kernel@...r.kernel.org; driverdev-devel@...uxdriverproject.org;
> olaf@...fle.de; apw@...onical.com; jasowang@...hat.com; KY Srinivasan;
> Haiyang Zhang; vkuznets@...hat.com
> Subject: Re: [PATCH] hv: hv_fcopy: drop the obsolete message on transfer
> failure
> 
> On Tue, Nov 11, 2014 at 09:03:26PM -0800, Dexuan Cui wrote:
> > In the case the user-space daemon crashes, hangs or is killed, we
> > need to down the semaphore, otherwise, after the daemon starts next
> > time, the obsolete data in fcopy_transaction.message or
> > fcopy_transaction.fcopy_msg will be used immediately.
> >
> > Cc: K. Y. Srinivasan <kys@...rosoft.com>
> > Signed-off-by: Dexuan Cui <decui@...rosoft.com>
> > ---
> >  drivers/hv/hv_fcopy.c | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> >
> > diff --git a/drivers/hv/hv_fcopy.c b/drivers/hv/hv_fcopy.c
> > index 23b2ce2..177122a 100644
> > --- a/drivers/hv/hv_fcopy.c
> > +++ b/drivers/hv/hv_fcopy.c
> > @@ -86,6 +86,15 @@ static void fcopy_work_func(struct work_struct
> *dummy)
> >  	 * process the pending transaction.
> >  	 */
> >  	fcopy_respond_to_host(HV_E_FAIL);
> > +
> > +	/* In the case the user-space daemon crashes, hangs or is killed, we
> > +	 * need to down the semaphore, otherwise, after the daemon starts
> next
> > +	 * time, the obsolete data in fcopy_transaction.message or
> > +	 * fcopy_transaction.fcopy_msg will be used immediately.
> > +	 */
> > +	if (down_trylock(&fcopy_transaction.read_sema))
> > +		pr_debug("FCP: failed to acquire the semaphore\n");
> 
> Why is "FCP:" needed?  pr_debug() should never need any type of prefix.
> 
> Please fix.
> 
> thanks,
> 
> greg k-h

Ok, I'll send a v2 soon.

Thanks,
-- Dexuan
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