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From:   "Gangurde, Abhijit" <abhijit.gangurde@amd.com>
To:     Greg KH <gregkh@linuxfoundation.org>
CC:     "masahiroy@kernel.org" <masahiroy@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Simek, Michal" <michal.simek@amd.com>,
        "git (AMD-Xilinx)" <git@amd.com>,
        "Agarwal, Nikhil" <nikhil.agarwal@amd.com>,
        "Gupta, Nipun" <Nipun.Gupta@amd.com>
Subject: RE: [PATCH v2 1/4] cdx: Introduce lock to protect controller ops and
 controller list
Thread-Topic: [PATCH v2 1/4] cdx: Introduce lock to protect controller ops and
 controller list
Thread-Index: AQHZw6fpekS7+sewHkWP9KKMIHa4dK/TzKGAgAEccwA=
Date:   Tue, 1 Aug 2023 08:34:00 +0000
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References: <20230731120813.123247-1-abhijit.gangurde@amd.com>
 <20230731120813.123247-2-abhijit.gangurde@amd.com>
 <2023073148-carried-unshaved-77e4@gregkh>
In-Reply-To: <2023073148-carried-unshaved-77e4@gregkh>
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> From: Greg KH <gregkh@linuxfoundation.org>
> Sent: Monday, July 31, 2023 5:55 PM
> To: Gangurde, Abhijit <abhijit.gangurde@amd.com>
> Cc: masahiroy@kernel.org; linux-kernel@vger.kernel.org; Simek, Michal
> <michal.simek@amd.com>; git (AMD-Xilinx) <git@amd.com>; Agarwal, Nikhil
> <nikhil.agarwal@amd.com>; Gupta, Nipun <Nipun.Gupta@amd.com>
> Subject: Re: [PATCH v2 1/4] cdx: Introduce lock to protect controller ops=
 and
> controller list
>=20
> On Mon, Jul 31, 2023 at 05:38:10PM +0530, Abhijit Gangurde wrote:
> > Add a mutex lock to prevent race between controller ops initiated by
> > the bus subsystem and the controller registration/unregistration.
> >
> > Signed-off-by: Abhijit Gangurde <abhijit.gangurde@amd.com>
> > ---
> >  drivers/cdx/cdx.c | 14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> >
> > diff --git a/drivers/cdx/cdx.c b/drivers/cdx/cdx.c
> > index d2cad4c670a0..66797c8fe400 100644
> > --- a/drivers/cdx/cdx.c
> > +++ b/drivers/cdx/cdx.c
> > @@ -72,6 +72,8 @@
> >
> >  /* CDX controllers registered with the CDX bus */
> >  static DEFINE_XARRAY_ALLOC(cdx_controllers);
> > +/* Lock to protect controller ops and controller list */
> > +static DEFINE_MUTEX(cdx_controller_lock);
>=20
> Wait, why do you have a local list and not just rely on the list the
> driver core has for you already?  Isn't this a duplicate list where you
> have objects on two different lists with a lifespan controlled only by
> one of them?

cdx_controllers list is holding just the controllers registered on the cdx =
bus system.
CDX devices are still maintained by driver core list. Controller list is us=
ed by rescan
which triggers rescan on all the controllers.

Thanks,
Abhijit