Nicholas Piggin <[email protected]> writes: > On 27 Feb. 2018 00:34, "Aneesh Kumar K.V" <[email protected]> > wrote: > > futex_detect_cmpxchg() does a cmpxchg_futex_value_locked on a NULL user > addr to > runtime detect whether architecture implements atomic cmpxchg for futex. > POWER > do implement the feature and hence we can enable the config instead of > depending > on runtime detection. > > We could possible enable this on everything. For now limitted to book3s_64 > > > I think everything implements it? Might as well do it all at once. > > I wouldn't mind putting in an explicit null dereference test if we take > this out.
If the config is not selected we do that with futex_detect_cmpxchg() right? Or are you suggesting something else? > > Thanks, > Nick > > > > Signed-off-by: Aneesh Kumar K.V <[email protected]> > --- > arch/powerpc/platforms/Kconfig.cputype | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/powerpc/platforms/Kconfig.cputype > b/arch/powerpc/platforms/Kconfig.cputype > index a429d859f15d..31bc2bd5dfd1 100644 > --- a/arch/powerpc/platforms/Kconfig.cputype > +++ b/arch/powerpc/platforms/Kconfig.cputype > @@ -75,6 +75,7 @@ config PPC_BOOK3S_64 > select ARCH_SUPPORTS_NUMA_BALANCING > select IRQ_WORK > select HAVE_KERNEL_XZ > + select HAVE_FUTEX_CMPXCHG if FUTEX > > config PPC_BOOK3E_64 > bool "Embedded processors" > -- > 2.14.3
