atomic_t: Cast to volatile when accessing atomic variables

In preparation for removing volatile from the atomic_t definition, this
patch adds a volatile cast to all the atomic read functions.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/sparc/include/asm/atomic_32.h b/arch/sparc/include/asm/atomic_32.h
index f0d343c..7ae128b 100644
--- a/arch/sparc/include/asm/atomic_32.h
+++ b/arch/sparc/include/asm/atomic_32.h
@@ -25,7 +25,7 @@
 extern int atomic_add_unless(atomic_t *, int, int);
 extern void atomic_set(atomic_t *, int);
 
-#define atomic_read(v)          ((v)->counter)
+#define atomic_read(v)          (*(volatile int *)&(v)->counter)
 
 #define atomic_add(i, v)	((void)__atomic_add_return( (int)(i), (v)))
 #define atomic_sub(i, v)	((void)__atomic_add_return(-(int)(i), (v)))