[PATCH 5/5] mm: add the __must_check attribute to {gfn,mfn}_add()

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

It's not obvious from the function itself whether the incremented value will be
stored in the parameter, or returned to the caller.  That has leads to bugs in
the past as callers assume the incremented value is stored in the parameter.

Add the __must_check attribute to the function to easily spot callers that
don't consume the returned value, which signals an error in the caller logic.

No functional change intended.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/include/xen/mm-frame.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/include/xen/mm-frame.h b/xen/include/xen/mm-frame.h
index 922ae418807a..c25e836f255a 100644
--- a/xen/include/xen/mm-frame.h
+++ b/xen/include/xen/mm-frame.h
@@ -23,7 +23,7 @@ TYPE_SAFE(unsigned long, mfn);
 #undef mfn_x
 #endif
 
-static inline mfn_t mfn_add(mfn_t mfn, unsigned long i)
+static inline mfn_t __must_check mfn_add(mfn_t mfn, unsigned long i)
 {
     return _mfn(mfn_x(mfn) + i);
 }
@@ -62,7 +62,7 @@ TYPE_SAFE(unsigned long, gfn);
 #undef gfn_x
 #endif
 
-static inline gfn_t gfn_add(gfn_t gfn, unsigned long i)
+static inline gfn_t __must_check gfn_add(gfn_t gfn, unsigned long i)
 {
     return _gfn(gfn_x(gfn) + i);
 }
-- 
2.43.0