[PATCH v2] xen/arm: gnttab: cast unused macro arguments to void

[Michal Orzel <michal.orzel@xxxxxxx>]

Function unmap_common_complete (common/grant_table.c) defines and sets
a variable ld that is later on passed to a macro:
gnttab_host_mapping_get_page_type().
On Arm this macro does not make use of any arguments causing a compiler
to warn about unused-but-set variable (when -Wunused-but-set-variable
is enabled). Fix it by casting the arguments to void in macro's body.

While there, take the opportunity to modify other macros in this file
that do not make use of all the arguments to prevent similar issues in
the future.

Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
---
Changes since v1:
-standalone patch carved out from a series (other patches already merged)
-v1 was ([3/8] gnttab: Remove unused-but-set variable)
-modify macro on Arm instead of removing ld variable
---
 xen/arch/arm/include/asm/grant_table.h | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/xen/arch/arm/include/asm/grant_table.h 
b/xen/arch/arm/include/asm/grant_table.h
index d31a4d6805..5bcd1ec528 100644
--- a/xen/arch/arm/include/asm/grant_table.h
+++ b/xen/arch/arm/include/asm/grant_table.h
@@ -31,10 +31,11 @@ static inline void gnttab_mark_dirty(struct domain *d, 
mfn_t mfn)
 
 int create_grant_host_mapping(unsigned long gpaddr, mfn_t mfn,
                               unsigned int flags, unsigned int cache_flags);
-#define gnttab_host_mapping_get_page_type(ro, ld, rd) (0)
+#define gnttab_host_mapping_get_page_type(ro, ld, rd) \
+    ((void)(ro), (void)(ld), (void)(rd), 0)
 int replace_grant_host_mapping(unsigned long gpaddr, mfn_t mfn,
                                unsigned long new_gpaddr, unsigned int flags);
-#define gnttab_release_host_mappings(domain) 1
+#define gnttab_release_host_mappings(domain) ((void)(domain), 1)
 
 /*
  * The region used by Xen on the memory will never be mapped in DOM0
@@ -89,10 +90,12 @@ int replace_grant_host_mapping(unsigned long gpaddr, mfn_t 
mfn,
 })
 
 #define gnttab_shared_gfn(d, t, i)                                       \
-    (((i) >= nr_grant_frames(t)) ? INVALID_GFN : (t)->arch.shared_gfn[i])
+    ((void)(d),                                                          \
+     ((i) >= nr_grant_frames(t)) ? INVALID_GFN : (t)->arch.shared_gfn[i])
 
-#define gnttab_status_gfn(d, t, i)                                       \
-    (((i) >= nr_status_frames(t)) ? INVALID_GFN : (t)->arch.status_gfn[i])
+#define gnttab_status_gfn(d, t, i)                                        \
+    ((void)(d),                                                           \
+     ((i) >= nr_status_frames(t)) ? INVALID_GFN : (t)->arch.status_gfn[i])
 
 #define gnttab_need_iommu_mapping(d)                    \
     (is_domain_direct_mapped(d) && is_iommu_enabled(d))
-- 
2.25.1