On Wed, Sep 2, 2015 at 11:23 AM, Pranith Kumar <bobby.pr...@gmail.com> wrote: > Hi Will, > > On 09/02/2015 05:59 AM, Will Deacon wrote: >> I just thought it was worth making this point, because it is prohibited >> in SC and I don't want people to think that our RELEASE/ACQUIRE operations >> are SC (even though they happen to be on arm64). > > This is interesting information. Does that mean that the following patch > should work? (I am not proposing to use it, just trying to understand if > REL+ACQ will act as a full barrier on ARM64, which you say it does). > > Thanks, > Pranith. > > diff --git a/arch/arm64/include/asm/cmpxchg.h > b/arch/arm64/include/asm/cmpxchg.h > index d8c25b7..14a1b35 100644 > --- a/arch/arm64/include/asm/cmpxchg.h > +++ b/arch/arm64/include/asm/cmpxchg.h > @@ -68,8 +68,7 @@ static inline unsigned long __xchg(unsigned long x, > volatile void *ptr, int size > BUILD_BUG(); > } > > - smp_mb(); > - return ret; > + return smp_load_acquire(ret);
I meant 'smp_load_acquire(&ret);' -- Pranith _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
