[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2 15/32] powerpc: define __smp_xxx
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 <mst@xxxxxxxxxx> > Acked-by: Arnd Bergmann <arnd@xxxxxxxx> > --- > 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@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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