Sorry, sent the wrong patch! Please ignore this one. Sending the v2 in another email.
On Wed, Feb 22, 2023 at 02:31:12PM +0530, Kautuk Consul wrote: > A link from ibm.com states: > "Ensures that all instructions preceding the call to __lwsync > complete before any subsequent store instructions can be executed > on the processor that executed the function. Also, it ensures that > all load instructions preceding the call to __lwsync complete before > any subsequent load instructions can be executed on the processor > that executed the function. This allows you to synchronize between > multiple processors with minimal performance impact, as __lwsync > does not wait for confirmation from each processor." > > Thats why smp_rmb() and smp_wmb() are defined to lwsync. > But this same understanding applies to parallel pipeline > execution on each PowerPC processor. > So, use the lwsync instruction for rmb() and wmb() on the PPC > architectures that support it. > > Also removed some useless spaces. > > Signed-off-by: Kautuk Consul <kcon...@linux.vnet.ibm.com> > --- > arch/powerpc/include/asm/barrier.h | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/include/asm/barrier.h > b/arch/powerpc/include/asm/barrier.h > index e80b2c0e9315..553f5a5d20bd 100644 > --- a/arch/powerpc/include/asm/barrier.h > +++ b/arch/powerpc/include/asm/barrier.h > @@ -41,11 +41,17 @@ > > /* The sub-arch has lwsync */ > #if defined(CONFIG_PPC64) || defined(CONFIG_PPC_E500MC) > -# define SMPWMB LWSYNC > +#undef rmb > +#undef wmb > +/* Redefine rmb() to lwsync. */ > +#define rmb() ({__asm__ __volatile__ ("lwsync" : : : "memory"); }) > +/* Redefine wmb() to lwsync. */ > +#define wmb() ({__asm__ __volatile__ ("lwsync" : : : "memory"); }) > +#define SMPWMB LWSYNC > #elif defined(CONFIG_BOOKE) > -# define SMPWMB mbar > +#define SMPWMB mbar > #else > -# define SMPWMB eieio > +#define SMPWMB eieio > #endif > > /* clang defines this macro for a builtin, which will not work with runtime > patching */ > -- > 2.31.1 >