percpu: Make __verify_pcu_ptr handle per cpu pointers to arrays

__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 <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
index 27ef6b1..57e890a 100644 (file)
--- a/include/linux/percpu-defs.h
+++ b/include/linux/percpu-defs.h
@@ -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)