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Commit b4eab7de authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by David S. Miller
Browse files

tools/virtio: copy READ/WRITE_ONCE 



This is to make ptr_ring test build again.

Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6dd42157

tools/virtio/ringtest/main.h

+57 −0
Original line number Diff line number Diff line
@@ -134,4 +134,61 @@ static inline void busy_wait(void) 
    barrier(); \

} while (0)



#if defined(__i386__) || defined(__x86_64__) || defined(__s390x__)

#define smp_wmb() barrier()

#else

#define smp_wmb() smp_release()

#endif



#ifdef __alpha__

#define smp_read_barrier_depends() smp_acquire()

#else

#define smp_read_barrier_depends() do {} while(0)

#endif



static __always_inline

void __read_once_size(const volatile void *p, void *res, int size)

{

        switch (size) {                                                 \

        case 1: *(unsigned char *)res = *(volatile unsigned char *)p; break;              \

        case 2: *(unsigned short *)res = *(volatile unsigned short *)p; break;            \

        case 4: *(unsigned int *)res = *(volatile unsigned int *)p; break;            \

        case 8: *(unsigned long long *)res = *(volatile unsigned long long *)p; break;            \

        default:                                                        \

                barrier();                                              \

                __builtin_memcpy((void *)res, (const void *)p, size);   \

                barrier();                                              \

        }                                                               \

}



static __always_inline void __write_once_size(volatile void *p, void *res, int size)

{

	switch (size) {

	case 1: *(volatile unsigned char *)p = *(unsigned char *)res; break;

	case 2: *(volatile unsigned short *)p = *(unsigned short *)res; break;

	case 4: *(volatile unsigned int *)p = *(unsigned int *)res; break;

	case 8: *(volatile unsigned long long *)p = *(unsigned long long *)res; break;

	default:

		barrier();

		__builtin_memcpy((void *)p, (const void *)res, size);

		barrier();

	}

}



#define READ_ONCE(x) \

({									\

	union { typeof(x) __val; char __c[1]; } __u;			\

	__read_once_size(&(x), __u.__c, sizeof(x));		\

	smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \

	__u.__val;							\

})



#define WRITE_ONCE(x, val) \

({							\

	union { typeof(x) __val; char __c[1]; } __u =	\

		{ .__val = (typeof(x)) (val) }; \

	__write_once_size(&(x), __u.__c, sizeof(x));	\

	__u.__val;					\

})



#endif