[PATCH] silence unused pgdat warning from alloc_bootmem_node and friends

x86 NUMA systems only define bootmem for node 0.  alloc_bootmem_node() and
friends therefore ignore the passed pgdat and use NODE_DATA(0) in all
cases.  This leads to the following warnings as we are not using the passed
parameter:

  .../mm/page_alloc.c: In function 'zone_wait_table_init':
  .../mm/page_alloc.c:2259: warning: unused variable 'pgdat'

One option would be to define all variables used with these macros
__attribute__ ((unused)), but this would leave us exposed should these
become genuinely unused.

The key here is that we _are_ using the value, we ignore it but that is a
deliberate action.  This patch adds a nested local variable within the
alloc_bootmem_node helper to which the pgdat parameter is assigned making
it 'used'.  The nested local is marked __attribute__ ((unused)) to silence
this same warning for it.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/asm-i386/mmzone.h

@@ -120,13 +120,26 @@ static inline int pfn_valid(int pfn)
 	__alloc_bootmem_node(NODE_DATA(0), (x), PAGE_SIZE, __pa(MAX_DMA_ADDRESS))
 #define alloc_bootmem_low_pages(x) \
 	__alloc_bootmem_node(NODE_DATA(0), (x), PAGE_SIZE, 0)
-#define alloc_bootmem_node(ignore, x) \
-	__alloc_bootmem_node(NODE_DATA(0), (x), SMP_CACHE_BYTES, __pa(MAX_DMA_ADDRESS))
-#define alloc_bootmem_pages_node(ignore, x) \
-	__alloc_bootmem_node(NODE_DATA(0), (x), PAGE_SIZE, __pa(MAX_DMA_ADDRESS))
-#define alloc_bootmem_low_pages_node(ignore, x) \
-	__alloc_bootmem_node(NODE_DATA(0), (x), PAGE_SIZE, 0)
-
+#define alloc_bootmem_node(pgdat, x)					\
+({									\
+	struct pglist_data  __attribute__ ((unused))			\
+				*__alloc_bootmem_node__pgdat = (pgdat);	\
+	__alloc_bootmem_node(NODE_DATA(0), (x), SMP_CACHE_BYTES,	\
+						__pa(MAX_DMA_ADDRESS));	\
+})
+#define alloc_bootmem_pages_node(pgdat, x)				\
+({									\
+	struct pglist_data  __attribute__ ((unused))			\
+				*__alloc_bootmem_node__pgdat = (pgdat);	\
+	__alloc_bootmem_node(NODE_DATA(0), (x), PAGE_SIZE,		\
+						__pa(MAX_DMA_ADDRESS))	\
+})
+#define alloc_bootmem_low_pages_node(pgdat, x)				\
+({									\
+	struct pglist_data  __attribute__ ((unused))			\
+				*__alloc_bootmem_node__pgdat = (pgdat);	\
+	__alloc_bootmem_node(NODE_DATA(0), (x), PAGE_SIZE, 0);		\
+})
 #endif /* CONFIG_NEED_MULTIPLE_NODES */
 
 #endif /* _ASM_MMZONE_H_ */