Commit 7e98b719 authored Dec 19, 2013 by H. Peter Anvin

x86, idle: Use static_cpu_has() for CLFLUSH workaround, add barriers

Use static_cpu_has() to conditionalize the CLFLUSH workaround, and add
memory barriers around it since the documentation is explicit that
CLFLUSH is only ordered with respect to MFENCE.

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

parent 16824255

arch/x86/include/asm/mwait.h

+4 −1

Original line number	Diff line number	Diff line
		@@ -43,8 +43,11 @@ static inline void __mwait(unsigned long eax, unsigned long ecx)
		static inline void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
		{
		if (!current_set_polling_and_test()) {
		if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR))
		if (static_cpu_has(X86_FEATURE_CLFLUSH_MONITOR)) {
		mb();
		clflush((void *)&current_thread_info()->flags);
		mb();
		}

		__monitor((void *)&current_thread_info()->flags, 0, 0);
		if (!need_resched())