x86, PAT: Change order of cpa and free in set_memory_wb

To be free of aliasing due to races, set_memory_* interfaces should
follow ordering of reserving, changing memtype to UC/WC, changing
memtype back to WB followed by free.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <20090409212708.512280000@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/mm/pageattr.c

@@ -1021,15 +1021,19 @@ int _set_memory_wb(unsigned long addr, int numpages)
 
 int set_memory_wb(unsigned long addr, int numpages)
 {
+	int ret = _set_memory_wb(addr, numpages);
 	free_memtype(__pa(addr), __pa(addr) + numpages * PAGE_SIZE);
-
-	return _set_memory_wb(addr, numpages);
+	return ret;
 }
 EXPORT_SYMBOL(set_memory_wb);
 
 int set_memory_array_wb(unsigned long *addr, int addrinarray)
 {
 	int i;
+	int ret;
+
+	ret = change_page_attr_clear(addr, addrinarray,
+				      __pgprot(_PAGE_CACHE_MASK), 1);
 
 	for (i = 0; i < addrinarray; i++) {
 		unsigned long start = __pa(addr[i]);
@@ -1042,8 +1046,7 @@ int set_memory_array_wb(unsigned long *addr, int addrinarray)
 		}
 		free_memtype(start, end);
 	}
-	return change_page_attr_clear(addr, addrinarray,
-				      __pgprot(_PAGE_CACHE_MASK), 1);
+	return ret;
 }
 EXPORT_SYMBOL(set_memory_array_wb);