[PATCH 2/2] Arm32: tidy the memset() macro

[Jan Beulich <jbeulich@xxxxxxxx>]

- add parentheses where they were missing (MISRA)
- make sure to evaluate also v exactly once (MISRA)
- remove excess parentheses
- rename local variables to not have leading underscores
- apply Xen coding style

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
I wonder whether "if ( n_ )" is really helpful: It's extra code in all
callers passing a non-constant size, just to cover a pretty rare case
which memset() is required to deal with correctly anyway, and which
__memzero() also handles quite fine from all I can tell.

--- a/xen/arch/arm/include/asm/string.h
+++ b/xen/arch/arm/include/asm/string.h
@@ -28,17 +28,19 @@
 
 void __memzero(void *ptr, size_t n);
 
-#define memset(p, v, n)                                                 \
-        ({                                                              \
-                void *__p = (p); size_t __n = n;                        \
-                if ((__n) != 0) {                                       \
-                        if (__builtin_constant_p((v)) && (v) == 0)      \
-                                __memzero((__p),(__n));                 \
-                        else                                            \
-                                memset((__p),(v),(__n));                \
-                }                                                       \
-                (__p);                                                  \
-        })
+#define memset(p, v, n)                                 \
+    ({                                                  \
+        void *p_ = (p); size_t n_ = (n);                \
+        typeof(v) v_ = (v);                             \
+        if ( n_ )                                       \
+        {                                               \
+            if ( __builtin_constant_p(v) && !v_ )       \
+                __memzero(p_, n_);                      \
+            else                                        \
+                memset(p_, v_, n_);                     \
+        }                                               \
+        p_;                                             \
+    })
 
 #endif