RE: [PATCH 086/117] Staging: hv: storvsc: Leverage the spinlock tomanage ref_cnt

[KY Srinivasan]

> -----Original Message-----
> From: Greg KH [mailto:greg@xxxxxxxxx]
> Sent: Tuesday, August 23, 2011 7:10 PM
> To: KY Srinivasan
> Cc: gregkh@xxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> devel@xxxxxxxxxxxxxxxxxxxxxx; virtualization@xxxxxxxxxxxxxx; Haiyang Zhang
> Subject: Re: [PATCH 086/117] Staging: hv: storvsc: Leverage the spinlock to
> manage ref_cnt
> 
> On Fri, Jul 15, 2011 at 10:47:14AM -0700, K. Y. Srinivasan wrote:
> > Now that we have a spin lock protecting access to the stor device pointer,
> > use it manage the reference count as well.
> >
> > Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> > Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> > ---
> >  drivers/staging/hv/hyperv_storage.h |    8 ++++----
> >  drivers/staging/hv/storvsc.c        |   10 +++++-----
> >  2 files changed, 9 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/staging/hv/hyperv_storage.h
> b/drivers/staging/hv/hyperv_storage.h
> > index 53b65be..d946211 100644
> > --- a/drivers/staging/hv/hyperv_storage.h
> > +++ b/drivers/staging/hv/hyperv_storage.h
> > @@ -265,7 +265,7 @@ struct storvsc_device {
> >  	struct hv_device *device;
> >
> >  	/* 0 indicates the device is being destroyed */
> > -	atomic_t ref_count;
> > +	int	 ref_count;
> 
> Is this really needed?  Can't you rely on the reference count of the
> hv_device itself?

We don't have a reference count on the hv_device and this count is taken
to deal with racing unloads and incoming traffic on the channel from the 
host. 

Regards,

K. Y

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