tools/virtio: remove smp_read_barrier_depends()

This gets rid of the last references to smp_read_barrier_depends()
 which for the kernel side was removed in v5.9. The serialization
required for Alpha is done inside READ_ONCE() instead of having
users deal with it. Simply use a full barrier, the architecture
does not have rmb in the first place.

Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Message-Id: <20221128034347.990-3-dave@stgolabs.net>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>

diff --git a/tools/virtio/ringtest/main.h b/tools/virtio/ringtest/main.h
index 9ed09ca..b68920d 100644 (file)
--- a/tools/virtio/ringtest/main.h
+++ b/tools/virtio/ringtest/main.h
@@ -140,12 +140,6 @@ static inline void busy_wait(void)
 #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)
 {
@@ -175,13 +169,22 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
        }
 }
 
+#ifdef __alpha__
 #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 */ \
+       smp_mb(); /* Enforce dependency ordering from x */              \
        __u.__val;                                                      \
 })
+#else
+#define READ_ONCE(x)                                                   \
+({                                                                     \
+       union { typeof(x) __val; char __c[1]; } __u;                    \
+       __read_once_size(&(x), __u.__c, sizeof(x));                     \
+       __u.__val;                                                      \
+})
+#endif
 
 #define WRITE_ONCE(x, val) \
 ({                                                     \