--- zzzz-none-000/linux-3.10.107/arch/x86/um/asm/barrier.h	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/arch/x86/um/asm/barrier.h	2021-02-04 17:41:59.000000000 +0000
@@ -29,43 +29,20 @@
 
 #endif /* CONFIG_X86_32 */
 
-#define read_barrier_depends()	do { } while (0)
-
-#ifdef CONFIG_SMP
-
-#define smp_mb()	mb()
 #ifdef CONFIG_X86_PPRO_FENCE
-#define smp_rmb()	rmb()
+#define dma_rmb()	rmb()
 #else /* CONFIG_X86_PPRO_FENCE */
-#define smp_rmb()	barrier()
+#define dma_rmb()	barrier()
 #endif /* CONFIG_X86_PPRO_FENCE */
+#define dma_wmb()	barrier()
 
-#ifdef CONFIG_X86_OOSTORE
-#define smp_wmb()	wmb()
-#else /* CONFIG_X86_OOSTORE */
+#define smp_mb()	barrier()
+#define smp_rmb()	barrier()
 #define smp_wmb()	barrier()
-#endif /* CONFIG_X86_OOSTORE */
-
-#define smp_read_barrier_depends()	read_barrier_depends()
-#define set_mb(var, value) do { (void)xchg(&var, value); } while (0)
-
-#else /* CONFIG_SMP */
 
-#include <asm-generic/barrier.h>
+#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); barrier(); } while (0)
 
-#endif /* CONFIG_SMP */
-
-/*
- * Stop RDTSC speculation. This is needed when you need to use RDTSC
- * (or get_cycles or vread that possibly accesses the TSC) in a defined
- * code region.
- *
- * (Could use an alternative three way for this if there was one.)
- */
-static inline void rdtsc_barrier(void)
-{
-	alternative(ASM_NOP3, "mfence", X86_FEATURE_MFENCE_RDTSC);
-	alternative(ASM_NOP3, "lfence", X86_FEATURE_LFENCE_RDTSC);
-}
+#define read_barrier_depends()		do { } while (0)
+#define smp_read_barrier_depends()	do { } while (0)
 
 #endif