| Message ID | 1451572003-2440-16-git-send-email-mst@redhat.com (mailing list archive) |
|---|---|
| State | Awaiting Upstream |
| Delegated to: | Geert Uytterhoeven |
| Headers | show |
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@redhat.com> > Acked-by: Arnd Bergmann <arnd@arndb.de> > --- > 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/ -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jan 05, 2016 at 09:36:55AM +0800, Boqun Feng wrote: > 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 I think this is the part that was missed in review. > > This reduces the amount of arch-specific boiler-plate code. > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > > Acked-by: Arnd Bergmann <arnd@arndb.de> > > --- > > 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? Yes. > > -#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. Absolutely. But smp_store_release (without __) will not. Please note I did test this: for ppc code before and after this patch generates exactly the same binary on SMP and 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 I think you missed the leading ___ :) smp_store_release is external and it needs __smp_lwsync as defined here. I can duplicate some code and have smp_lwsync *not* call __smp_lwsync but why do this? Still, if you prefer it this way, please let me know. > > 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/ -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jan 05, 2016 at 10:51:17AM +0200, Michael S. Tsirkin wrote: > On Tue, Jan 05, 2016 at 09:36:55AM +0800, Boqun Feng wrote: > > 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 > > I think this is the part that was missed in review. > Yes, I realized my mistake after reread the series. But smp_lwsync() is not defined in asm-generic/barriers.h, right? > > > This reduces the amount of arch-specific boiler-plate code. > > > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > > > Acked-by: Arnd Bergmann <arnd@arndb.de> > > > --- > > > 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? > > Yes. > > > > -#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. > > Absolutely. But smp_store_release (without __) will not. > > Please note I did test this: for ppc code before and after > this patch generates exactly the same binary on SMP and UP. > Yes, you're right, sorry for my mistake... > > > 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 > > I think you missed the leading ___ :) > What I mean here was smp_lwsync() was originally internal to PPC, but never mind ;-) > smp_store_release is external and it needs __smp_lwsync as > defined here. > > I can duplicate some code and have smp_lwsync *not* call __smp_lwsync You mean bringing smp_lwsync() back? because I haven't seen you defining in asm-generic/barriers.h in previous patches and you just delete it in this patch. > but why do this? Still, if you prefer it this way, > please let me know. > I think deleting smp_lwsync() is fine, though I need to change atomic variants patches on PPC because of it ;-/ 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/ -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jan 05, 2016 at 05:53:41PM +0800, Boqun Feng wrote: > On Tue, Jan 05, 2016 at 10:51:17AM +0200, Michael S. Tsirkin wrote: > > On Tue, Jan 05, 2016 at 09:36:55AM +0800, Boqun Feng wrote: > > > 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 > > > > I think this is the part that was missed in review. > > > > Yes, I realized my mistake after reread the series. But smp_lwsync() is > not defined in asm-generic/barriers.h, right? It isn't because as far as I could tell it is not used outside arch/powerpc/include/asm/barrier.h smp_store_release and smp_load_acquire. And these are now gone. Instead there are __smp_store_release and __smp_load_acquire which call __smp_lwsync. These are only used for virt and on SMP. UP variants are generic - they just call barrier(). > > > > This reduces the amount of arch-specific boiler-plate code. > > > > > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > > > > Acked-by: Arnd Bergmann <arnd@arndb.de> > > > > --- > > > > 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? > > > > Yes. > > > > > > -#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. > > > > Absolutely. But smp_store_release (without __) will not. > > > > Please note I did test this: for ppc code before and after > > this patch generates exactly the same binary on SMP and UP. > > > > Yes, you're right, sorry for my mistake... > > > > > > 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 > > > > I think you missed the leading ___ :) > > > > What I mean here was smp_lwsync() was originally internal to PPC, but > never mind ;-) > > > smp_store_release is external and it needs __smp_lwsync as > > defined here. > > > > I can duplicate some code and have smp_lwsync *not* call __smp_lwsync > > You mean bringing smp_lwsync() back? because I haven't seen you defining > in asm-generic/barriers.h in previous patches and you just delete it in > this patch. > > > but why do this? Still, if you prefer it this way, > > please let me know. > > > > I think deleting smp_lwsync() is fine, though I need to change atomic > variants patches on PPC because of it ;-/ > > Regards, > Boqun Sorry, I don't understand - why do you have to do anything? I changed all users of smp_lwsync so they use __smp_lwsync on SMP and barrier() on !SMP. This is exactly the current behaviour, I also tested that generated code does not change at all. Is there a patch in your tree that conflicts with this? > > > > 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/ -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jan 05, 2016 at 06:16:48PM +0200, Michael S. Tsirkin wrote: [snip] > > > > 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 > > > > > > I think you missed the leading ___ :) > > > > > > > What I mean here was smp_lwsync() was originally internal to PPC, but > > never mind ;-) > > > > > smp_store_release is external and it needs __smp_lwsync as > > > defined here. > > > > > > I can duplicate some code and have smp_lwsync *not* call __smp_lwsync > > > > You mean bringing smp_lwsync() back? because I haven't seen you defining > > in asm-generic/barriers.h in previous patches and you just delete it in > > this patch. > > > > > but why do this? Still, if you prefer it this way, > > > please let me know. > > > > > > > I think deleting smp_lwsync() is fine, though I need to change atomic > > variants patches on PPC because of it ;-/ > > > > Regards, > > Boqun > > Sorry, I don't understand - why do you have to do anything? > I changed all users of smp_lwsync so they > use __smp_lwsync on SMP and barrier() on !SMP. > > This is exactly the current behaviour, I also tested that > generated code does not change at all. > > Is there a patch in your tree that conflicts with this? > Because in a patchset which implements atomic relaxed/acquire/release variants on PPC I use smp_lwsync(), this makes it have another user, please see this mail: http://article.gmane.org/gmane.linux.ports.ppc.embedded/89877 in definition of PPC's __atomic_op_release(). But I think removing smp_lwsync() is a good idea and actually I think we can go further to remove __smp_lwsync() and let __smp_load_acquire and __smp_store_release call __lwsync() directly, but that is another thing. Anyway, I will modify my patch. 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/ -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, Jan 06, 2016 at 09:51:52AM +0800, Boqun Feng wrote: > On Tue, Jan 05, 2016 at 06:16:48PM +0200, Michael S. Tsirkin wrote: > [snip] > > > > > 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 > > > > > > > > I think you missed the leading ___ :) > > > > > > > > > > What I mean here was smp_lwsync() was originally internal to PPC, but > > > never mind ;-) > > > > > > > smp_store_release is external and it needs __smp_lwsync as > > > > defined here. > > > > > > > > I can duplicate some code and have smp_lwsync *not* call __smp_lwsync > > > > > > You mean bringing smp_lwsync() back? because I haven't seen you defining > > > in asm-generic/barriers.h in previous patches and you just delete it in > > > this patch. > > > > > > > but why do this? Still, if you prefer it this way, > > > > please let me know. > > > > > > > > > > I think deleting smp_lwsync() is fine, though I need to change atomic > > > variants patches on PPC because of it ;-/ > > > > > > Regards, > > > Boqun > > > > Sorry, I don't understand - why do you have to do anything? > > I changed all users of smp_lwsync so they > > use __smp_lwsync on SMP and barrier() on !SMP. > > > > This is exactly the current behaviour, I also tested that > > generated code does not change at all. > > > > Is there a patch in your tree that conflicts with this? > > > > Because in a patchset which implements atomic relaxed/acquire/release > variants on PPC I use smp_lwsync(), this makes it have another user, > please see this mail: > > http://article.gmane.org/gmane.linux.ports.ppc.embedded/89877 > > in definition of PPC's __atomic_op_release(). > > > But I think removing smp_lwsync() is a good idea and actually I think we > can go further to remove __smp_lwsync() and let __smp_load_acquire and > __smp_store_release call __lwsync() directly, but that is another thing. > > Anyway, I will modify my patch. > > Regards, > Boqun Thanks! Could you send an ack then please? > > > > > > > > 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/ -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, Jan 06, 2016 at 10:23:51PM +0200, Michael S. Tsirkin wrote: [...] > > > > > > Sorry, I don't understand - why do you have to do anything? > > > I changed all users of smp_lwsync so they > > > use __smp_lwsync on SMP and barrier() on !SMP. > > > > > > This is exactly the current behaviour, I also tested that > > > generated code does not change at all. > > > > > > Is there a patch in your tree that conflicts with this? > > > > > > > Because in a patchset which implements atomic relaxed/acquire/release > > variants on PPC I use smp_lwsync(), this makes it have another user, > > please see this mail: > > > > http://article.gmane.org/gmane.linux.ports.ppc.embedded/89877 > > > > in definition of PPC's __atomic_op_release(). > > > > > > But I think removing smp_lwsync() is a good idea and actually I think we > > can go further to remove __smp_lwsync() and let __smp_load_acquire and > > __smp_store_release call __lwsync() directly, but that is another thing. > > > > Anyway, I will modify my patch. > > > > Regards, > > Boqun > > > Thanks! > Could you send an ack then please? > Sure, if you need one from me, feel free to add my ack for this patch: Acked-by: Boqun Feng <boqun.feng@gmail.com> Regards, Boqun
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() -#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(); \ 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; \ })