__verify_pcpu_ptr() will cause a compilation failure if the type of the
pointer is a pointer to a fixed array of objects. Adding zero to the
pointer converts the type of pointer to that pointing to a single
object of the array.

Signed-off-by: Christoph Lameter <c...@linux.com>

Index: linux/include/linux/percpu-defs.h
===================================================================
--- linux.orig/include/linux/percpu-defs.h      2013-08-22 13:39:04.000000000 
-0500
+++ linux/include/linux/percpu-defs.h   2013-08-22 13:41:15.333140537 -0500
@@ -22,9 +22,12 @@
  * Macro which verifies @ptr is a percpu pointer without evaluating
  * @ptr.  This is to be used in percpu accessors to verify that the
  * input parameter is a percpu pointer.
+ *
+ * + 0 is required in order to convert the pointer type from a
+ * potential array type to a pointer to a single item of the array.
  */
 #define __verify_pcpu_ptr(ptr) do {                                    \
-       const void __percpu *__vpp_verify = (typeof(ptr))NULL;          \
+       const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL;    \
        (void)__vpp_verify;                                             \
 } while (0)
 

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