On Tue, Aug 05, 2014 at 09:57:51AM +0200, Christian Borntraeger wrote: > commit 4badad352a6bb202ec68afa7a574c0bb961e5ebc (locking/mutex: Disable > optimistic spinning on some architectures) fenced spinning for > architectures without proper cmpxchg. > There is no need to disable mutex spinning on s390, though: > The instructions CS,CSG and friends provide the proper guarantees. > (We dont implement cmpxchg with locks). > > Please note: This is a quick fix for s390, suitable for stable > as 3.16 unintenionally disabled optimistic spinning. > > The proper fix is probably to use ARCH_HAVE_NMI_SAFE_CMPXCHG > instead of introducing ARCH_SUPPORTS_ATOMIC_RMW. > > Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> > CC: <mingo@xxxxxxxxxx> > CC: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > CC: stable@xxxxxxxxxxxxxxx > --- > arch/s390/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig > index 9a0ea87..eab3c32 100644 > --- a/arch/s390/Kconfig > +++ b/arch/s390/Kconfig > @@ -63,6 +63,7 @@ config S390 > select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE > select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS > select ARCH_HAVE_NMI_SAFE_CMPXCHG > + select ARCH_SUPPORTS_ATOMIC_RMW > select ARCH_INLINE_READ_LOCK > select ARCH_INLINE_READ_LOCK_BH > select ARCH_INLINE_READ_LOCK_IRQ This can go in via the s390 tree. I applied your patch and changed it a bit to keep Kconfig sorted. Thanks! -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
