Date:   Wed, 22 Feb 2023 15:16:54 +0530
From:   Kautuk Consul <kconsul@linux.vnet.ibm.com>
To:     Christophe Leroy <christophe.leroy@csgroup.eu>
Cc:     Michael Ellerman <mpe@ellerman.id.au>,
        Nicholas Piggin <npiggin@gmail.com>,
        Rohan McLure <rmclure@linux.ibm.com>,
        "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] arch/powerpc/include/asm/barrier.h: redefine rmb and
 wmb to lwsync
Message-ID: <Y/XkjobvDPFErM7J@li-a450e7cc-27df-11b2-a85c-b5a9ac31e8ef.ibm.com>
References: <20230222090344.189270-1-kconsul@linux.vnet.ibm.com>
 <c4dcf969-0836-cc78-63d9-db83b9ebfa1d@csgroup.eu>
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> 
> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Thanks!
> 
> > ---
> >   arch/powerpc/include/asm/barrier.h | 7 +++++++
> >   1 file changed, 7 insertions(+)
> > 
> > diff --git a/arch/powerpc/include/asm/barrier.h b/arch/powerpc/include/asm/barrier.h
> > index b95b666f0374..e088dacc0ee8 100644
> > --- a/arch/powerpc/include/asm/barrier.h
> > +++ b/arch/powerpc/include/asm/barrier.h
> > @@ -36,8 +36,15 @@
> >    * heavy-weight sync, so smp_wmb() can be a lighter-weight eieio.
> >    */
> >   #define __mb()   __asm__ __volatile__ ("sync" : : : "memory")
> > +
> > +/* The sub-arch has lwsync. */
> > +#if defined(CONFIG_PPC64) || defined(CONFIG_PPC_E500MC)
> > +#define __rmb() __asm__ __volatile__ ("lwsync" : : : "memory")
> > +#define __wmb() __asm__ __volatile__ ("lwsync" : : : "memory")
> 
> I'd have preferred with 'asm volatile' though.
Sorry about that! That wasn't the intent of this patch.
Probably another patch series should change this manner of #defining
assembly.