[PATCH] libibverbs: add ARM64 memory barrier macros

[Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>]

The default generic barriers are not correct for ARM64. This results in
data corruption.  The correct macros are lifted from the linux kernel.

Signed-off-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
---

Changes since RFC:

no change to the patch - just productive discussion about these barrier
implementations.  I propose we proceed to add this patch since it resolves
a data corruption bug.
---
 include/infiniband/arch.h |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/include/infiniband/arch.h b/include/infiniband/arch.h
index bc1738a..71f02f8 100644
--- a/include/infiniband/arch.h
+++ b/include/infiniband/arch.h
@@ -122,6 +122,15 @@ static inline uint64_t ntohll(uint64_t x) { return x; }
 #define wmb()	mb()					/* for s390x */
 #define wc_wmb() wmb()					/* for s390x */
 
+#elif defined(__aarch64__)
+
+#define dsb(opt)	asm volatile("dsb " #opt : : : "memory")
+
+#define mb()	dsb(sy)
+#define rmb()	dsb(ld)
+#define wmb()	dsb(st)
+#define wc_wmb() wmb()
+
 #else
 
 #warning No architecture specific defines found.  Using generic implementation.
-- 
1.7.1

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