syslet: add proper read barrier between user_tail and completion read
Also fixup a bug with ring indexing, it needs to use the real ring size
mask, not the io depth.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/arch/arch-s390.h b/arch/arch-s390.h
index ed5d462..5e13155 100644
--- a/arch/arch-s390.h
+++ b/arch/arch-s390.h
@@ -14,5 +14,6 @@
#define nop asm volatile ("diag 0,0,68" : : : "memory")
#define fio_ffz(v) generic_ffz((v))
+#define read_barrier() asm volatile("bcr 15,0" : : : "memory")
#endif