[PATCH] xen/balloon: add header guard

[Roger Pau Monne <roger.pau@citrix.com>]

In order to protect against the header being included multiple times
on the same compilation unit.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: xen-devel@lists.xenproject.org
---
This is required as a pre-patch to use ZONE_DEVICE, or else the
fallback of including the balloon header might not work properly.
---
 include/xen/balloon.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/xen/balloon.h b/include/xen/balloon.h
index 6fb95aa19405..6dbdb0b3fd03 100644
--- a/include/xen/balloon.h
+++ b/include/xen/balloon.h
@@ -2,6 +2,8 @@
 /******************************************************************************
  * Xen balloon functionality
  */
+#ifndef _XEN_BALLOON_H
+#define _XEN_BALLOON_H
 
 #define RETRY_UNLIMITED	0
 
@@ -34,3 +36,5 @@ static inline void xen_balloon_init(void)
 {
 }
 #endif
+
+#endif	/* _XEN_BALLOON_H */
-- 
2.27.0