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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
This commit is contained in:
H. Peter Anvin 2013-12-19 11:58:16 -08:00
parent 1682425539
commit 7e98b71920
1 changed files with 4 additions and 1 deletions
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5
arch/x86/include/asm/mwait.h
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@ -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())