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tools/virtio: copy READ/WRITE_ONCE 

This is to make ptr_ring test build again.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Michael S. Tsirkin 2018-01-26 01:36:42 +02:00 committed by David S. Miller
parent 6dd4215783
commit b4eab7de66
1 changed files with 57 additions and 0 deletions
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57
tools/virtio/ringtest/main.h
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@ -134,4 +134,61 @@ static inline void busy_wait(void)
barrier(); \ barrier(); \
} while (0) } 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 #endif