wmb                20 arch/x86/include/asm/barrier.h #define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
wmb                24 arch/x86/include/asm/barrier.h #define wmb()	asm volatile("sfence" ::: "memory")
wmb                42 include/asm-generic/barrier.h #define wmb()	mb()