linux/arch/arm/mach-realview/include/mach/barriers.h - nest-guard/1.0/linux - Git at Google

 /*
  * Barriers redefined for RealView ARM11MPCore platforms with L220 cache
  * controller to work around hardware errata causing the outer_sync()
  * operation to deadlock the system.
  */
 #define mb()		dsb()
 #define rmb()		dmb()
 #define wmb()		mb()
	/*
	* Barriers redefined for RealView ARM11MPCore platforms with L220 cache
	* controller to work around hardware errata causing the outer_sync()
	* operation to deadlock the system.
	*/
	#define mb() dsb()
	#define rmb() dmb()
	#define wmb() mb()