libvirt/internal.h-Introduce-and-use-VIR_IS_POW2.patch

From d568dc527cd3098df2460d3e991efe3ad8b80410 Mon Sep 17 00:00:00 2001
From: Michal Privoznik <mprivozn@redhat.com>
Date: Wed, 4 Nov 2020 19:41:27 +0100
Subject: [PATCH] internal.h: Introduce and use VIR_IS_POW2()

This macro checks whether given number is an integer power of
two. At the same time, I've identified two places where we check
for pow2 and I'm replacing them with the macro.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Tested-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Tested-by: Han Han <hhan@redhat.com>
Reviewed-by: Shaokun Wei <weishaokun@kylinos.cn>
---
 src/internal.h       | 9 +++++++++
 src/util/virrandom.c | 2 +-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/internal.h b/src/internal.h
index 440f01d370..40c993977a 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -216,6 +216,15 @@
         (a) = (a) ^ (b); \
     } while (0)
 
+/**
+ * VIR_IS_POW2:
+ *
+ * Returns true if given number is a power of two
+ */
+#define VIR_IS_POW2(x) \
+    ((x) && !((x) & ((x) - 1)))
+
+
 /**
  * virCheckFlags:
  * @supported: an OR'ed set of supported flags
diff --git a/src/util/virrandom.c b/src/util/virrandom.c
index 1b4102cf58..500f55c956 100644
--- a/src/util/virrandom.c
+++ b/src/util/virrandom.c
@@ -89,7 +89,7 @@ double virRandom(void)
  */
 uint32_t virRandomInt(uint32_t max)
 {
-    if ((max & (max - 1)) == 0)
+    if (VIR_IS_POW2(max))
         return virRandomBits(__builtin_ffs(max) - 1);
 
     double val = virRandom();
-- 
2.27.0