[PATCH] xen/balloon: fix unused-variable warning

[Arnd Bergmann <arnd@xxxxxxxxxx>]

From: Arnd Bergmann <arnd@xxxxxxxx>

In configurations with CONFIG_XEN_BALLOON_MEMORY_HOTPLUG=n
and CONFIG_XEN_BALLOON_MEMORY_HOTPLUG=y, gcc warns about an
unused variable:

drivers/xen/balloon.c:83:12: error: 'xen_hotplug_unpopulated' defined but not 
used [-Werror=unused-variable]

Since this is always zero when CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
is disabled, turn it into a preprocessor constant in that case.

Fixes: 121f2faca2c0 ("xen/balloon: rename alloc/free_xenballooned_pages")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
 drivers/xen/balloon.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index ad9ba1e97450..ba2ea11e0d3d 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -80,9 +80,8 @@
 static uint __read_mostly balloon_boot_timeout = 180;
 module_param(balloon_boot_timeout, uint, 0444);
 
-static int xen_hotplug_unpopulated;
-
 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+static int xen_hotplug_unpopulated;
 
 static struct ctl_table balloon_table[] = {
        {
@@ -115,6 +114,8 @@ static struct ctl_table xen_root[] = {
        { }
 };
 
+#else
+#define xen_hotplug_unpopulated 0
 #endif
 
 /*
-- 
2.29.2