From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boqun Feng Subject: Re: [PATCH v2 15/32] powerpc: define __smp_xxx Date: Tue, 5 Jan 2016 09:36:55 +0800 Message-ID: <20160105013648.GA1256@fixme-laptop.cn.ibm.com> References: <1451572003-2440-1-git-send-email-mst@redhat.com> <1451572003-2440-16-git-send-email-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-ob0-f194.google.com ([209.85.214.194]:32861 "EHLO mail-ob0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753756AbcAEBhd (ORCPT ); Mon, 4 Jan 2016 20:37:33 -0500 Content-Disposition: inline In-Reply-To: <1451572003-2440-16-git-send-email-mst@redhat.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Arnd Bergmann , linux-arch@vger.kernel.org, Andrew Cooper , virtualization@lists.linux-foundation.org, Stefano Stabellini , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , David Miller , linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-metag@vger.kernel.org, linux-mips@linux-mips.org, x86@kernel.org, user-mode-linux-devel@lists.sourceforge.net, adi-buildroot-devel@lists.sourceforge.net, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, xen-devel@lists.xenproject.org, Benjamin Herrenschmidt , Paul Mackerras Hi Michael, On Thu, Dec 31, 2015 at 09:07:42PM +0200, Michael S. Tsirkin wrote: > This defines __smp_xxx barriers for powerpc > for use by virtualization. > > smp_xxx barriers are removed as they are > defined correctly by asm-generic/barriers.h > > This reduces the amount of arch-specific boiler-plate code. > > Signed-off-by: Michael S. Tsirkin > Acked-by: Arnd Bergmann > --- > arch/powerpc/include/asm/barrier.h | 24 ++++++++---------------- > 1 file changed, 8 insertions(+), 16 deletions(-) > > diff --git a/arch/powerpc/include/asm/barrier.h b/arch/powerpc/include/asm/barrier.h > index 980ad0c..c0deafc 100644 > --- a/arch/powerpc/include/asm/barrier.h > +++ b/arch/powerpc/include/asm/barrier.h > @@ -44,19 +44,11 @@ > #define dma_rmb() __lwsync() > #define dma_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory") > > -#ifdef CONFIG_SMP > -#define smp_lwsync() __lwsync() > +#define __smp_lwsync() __lwsync() > so __smp_lwsync() is always mapped to lwsync, right? > -#define smp_mb() mb() > -#define smp_rmb() __lwsync() > -#define smp_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory") > -#else > -#define smp_lwsync() barrier() > - > -#define smp_mb() barrier() > -#define smp_rmb() barrier() > -#define smp_wmb() barrier() > -#endif /* CONFIG_SMP */ > +#define __smp_mb() mb() > +#define __smp_rmb() __lwsync() > +#define __smp_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory") > > /* > * This is a barrier which prevents following instructions from being > @@ -67,18 +59,18 @@ > #define data_barrier(x) \ > asm volatile("twi 0,%0,0; isync" : : "r" (x) : "memory"); > > -#define smp_store_release(p, v) \ > +#define __smp_store_release(p, v) \ > do { \ > compiletime_assert_atomic_type(*p); \ > - smp_lwsync(); \ > + __smp_lwsync(); \ , therefore this will emit an lwsync no matter SMP or UP. Another thing is that smp_lwsync() may have a third user(other than smp_load_acquire() and smp_store_release()): http://article.gmane.org/gmane.linux.ports.ppc.embedded/89877 I'm OK to change my patch accordingly, but do we really want smp_lwsync() get involved in this cleanup? If I understand you correctly, this cleanup focuses on external API like smp_{r,w,}mb(), while smp_lwsync() is internal to PPC. Regards, Boqun > WRITE_ONCE(*p, v); \ > } while (0) > > -#define smp_load_acquire(p) \ > +#define __smp_load_acquire(p) \ > ({ \ > typeof(*p) ___p1 = READ_ONCE(*p); \ > compiletime_assert_atomic_type(*p); \ > - smp_lwsync(); \ > + __smp_lwsync(); \ > ___p1; \ > }) > > -- > MST > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-f194.google.com ([209.85.214.194]:32861 "EHLO mail-ob0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753756AbcAEBhd (ORCPT ); Mon, 4 Jan 2016 20:37:33 -0500 Date: Tue, 5 Jan 2016 09:36:55 +0800 From: Boqun Feng Subject: Re: [PATCH v2 15/32] powerpc: define __smp_xxx Message-ID: <20160105013648.GA1256@fixme-laptop.cn.ibm.com> References: <1451572003-2440-1-git-send-email-mst@redhat.com> <1451572003-2440-16-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1451572003-2440-16-git-send-email-mst@redhat.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Arnd Bergmann , linux-arch@vger.kernel.org, Andrew Cooper , virtualization@lists.linux-foundation.org, Stefano Stabellini , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , David Miller , linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-metag@vger.kernel.org, linux-mips@linux-mips.org, x86@kernel.org, user-mode-linux-devel@lists.sourceforge.net, adi-buildroot-devel@lists.sourceforge.net, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, xen-devel@lists.xenproject.org, Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Ingo Molnar , Davidlohr Bueso , Andrey Konovalov , "Paul E. McKenney" Message-ID: <20160105013655.HPExiY7taSX6999mGjmjyV4DRe7S6fMQj5XC_TztjZg@z> Hi Michael, On Thu, Dec 31, 2015 at 09:07:42PM +0200, Michael S. Tsirkin wrote: > This defines __smp_xxx barriers for powerpc > for use by virtualization. > > smp_xxx barriers are removed as they are > defined correctly by asm-generic/barriers.h > > This reduces the amount of arch-specific boiler-plate code. > > Signed-off-by: Michael S. Tsirkin > Acked-by: Arnd Bergmann > --- > arch/powerpc/include/asm/barrier.h | 24 ++++++++---------------- > 1 file changed, 8 insertions(+), 16 deletions(-) > > diff --git a/arch/powerpc/include/asm/barrier.h b/arch/powerpc/include/asm/barrier.h > index 980ad0c..c0deafc 100644 > --- a/arch/powerpc/include/asm/barrier.h > +++ b/arch/powerpc/include/asm/barrier.h > @@ -44,19 +44,11 @@ > #define dma_rmb() __lwsync() > #define dma_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory") > > -#ifdef CONFIG_SMP > -#define smp_lwsync() __lwsync() > +#define __smp_lwsync() __lwsync() > so __smp_lwsync() is always mapped to lwsync, right? > -#define smp_mb() mb() > -#define smp_rmb() __lwsync() > -#define smp_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory") > -#else > -#define smp_lwsync() barrier() > - > -#define smp_mb() barrier() > -#define smp_rmb() barrier() > -#define smp_wmb() barrier() > -#endif /* CONFIG_SMP */ > +#define __smp_mb() mb() > +#define __smp_rmb() __lwsync() > +#define __smp_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory") > > /* > * This is a barrier which prevents following instructions from being > @@ -67,18 +59,18 @@ > #define data_barrier(x) \ > asm volatile("twi 0,%0,0; isync" : : "r" (x) : "memory"); > > -#define smp_store_release(p, v) \ > +#define __smp_store_release(p, v) \ > do { \ > compiletime_assert_atomic_type(*p); \ > - smp_lwsync(); \ > + __smp_lwsync(); \ , therefore this will emit an lwsync no matter SMP or UP. Another thing is that smp_lwsync() may have a third user(other than smp_load_acquire() and smp_store_release()): http://article.gmane.org/gmane.linux.ports.ppc.embedded/89877 I'm OK to change my patch accordingly, but do we really want smp_lwsync() get involved in this cleanup? If I understand you correctly, this cleanup focuses on external API like smp_{r,w,}mb(), while smp_lwsync() is internal to PPC. Regards, Boqun > WRITE_ONCE(*p, v); \ > } while (0) > > -#define smp_load_acquire(p) \ > +#define __smp_load_acquire(p) \ > ({ \ > typeof(*p) ___p1 = READ_ONCE(*p); \ > compiletime_assert_atomic_type(*p); \ > - smp_lwsync(); \ > + __smp_lwsync(); \ > ___p1; \ > }) > > -- > MST > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/