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

KY Srinivasan
2011-08-24T00:58:42Z

> -----Original Message-----
> From: Greg KH [mailto:greg@kroah.com]
> Sent: Tuesday, August 23, 2011 7:10 PM
> To: KY Srinivasan
> Cc: gregkh@suse.de; linux-kernel@vger.kernel.org;
> devel@linuxdriverproject.org; virtualization@lists.osdl.org; 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@microsoft.com>
> > Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> > ---
> > 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