[PATCH 4.9 26/95] powerpc/64: Fix smp_wmb barrier definition use use lwsync consistently

From: Greg Kroah-Hartman
Date: Sun Apr 22 2018 - 10:13:41 EST

4.9-stable review patch. If anyone has any objections, please let me know.


From: Nicholas Piggin <npiggin@xxxxxxxxx>

commit 0bfdf598900fd62869659f360d3387ed80eb71cf upstream.

asm/barrier.h is not always included after asm/synch.h, which meant
it was missing __SUBARCH_HAS_LWSYNC, so in some files smp_wmb() would
be eieio when it should be lwsync. kernel/time/hrtimer.c is one case.

__SUBARCH_HAS_LWSYNC is only used in one place, so just fold it in
to where it's used. Previously with my small simulator config, 377
instances of eieio in the tree. After this patch there are 55.

Fixes: 46d075be585e ("powerpc: Optimise smp_wmb")
Cc: stable@xxxxxxxxxxxxxxx # v2.6.29+
Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

arch/powerpc/include/asm/barrier.h | 3 ++-
arch/powerpc/include/asm/synch.h | 4 ----
2 files changed, 2 insertions(+), 5 deletions(-)

--- a/arch/powerpc/include/asm/barrier.h
+++ b/arch/powerpc/include/asm/barrier.h
@@ -34,7 +34,8 @@
#define rmb() __asm__ __volatile__ ("sync" : : : "memory")
#define wmb() __asm__ __volatile__ ("sync" : : : "memory")

+/* The sub-arch has lwsync */
+#if defined(__powerpc64__) || defined(CONFIG_PPC_E500MC)
# define SMPWMB eieio
--- a/arch/powerpc/include/asm/synch.h
+++ b/arch/powerpc/include/asm/synch.h
@@ -5,10 +5,6 @@
#include <linux/stringify.h>
#include <asm/feature-fixups.h>

-#if defined(__powerpc64__) || defined(CONFIG_PPC_E500MC)
#ifndef __ASSEMBLY__
extern unsigned int __start___lwsync_fixup, __stop___lwsync_fixup;
extern void do_lwsync_fixups(unsigned long value, void *fixup_start,