x86, idle: Add memory barriers around clflush in mwait_play_dead()
For consistency with mwait_idle_with_hints(). Not sure they help, but
they really won't hurt...
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Len Brown <len.brown@intel.com>
Link: http://lkml.kernel.org/r/CA%2B55aFzGxcML7j8CEvQPYzh0W81uVoAAVmGctMOUZ7CZ1yYd2A@mail.gmail.com
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 85dc05a..f5252c4 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1417,7 +1417,9 @@
* The WBINVD is insufficient due to the spurious-wakeup
* case where we return around the loop.
*/
+ mb();
clflush(mwait_ptr);
+ mb();
__monitor(mwait_ptr, 0, 0);
mb();
__mwait(eax, 0);
