[PATCH] memory hotplug prep: __section_nr helper

[linux-2.6-omap-h63xx.git] / mm / sparse.c

diff --git a/mm/sparse.c b/mm/sparse.c
index 347249a4917afa922f4c8ae5d38fbfe81c189a5a..0d3bd4bf3aaa1a76c28106b3776b3fd304c7ab99 100644 (file)
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -72,6 +72,31 @@ static inline int sparse_index_init(unsigned long section_nr, int nid)
 }
 #endif
 
+/*
+ * Although written for the SPARSEMEM_EXTREME case, this happens
+ * to also work for the flat array case becase
+ * NR_SECTION_ROOTS==NR_MEM_SECTIONS.
+ */
+int __section_nr(struct mem_section* ms)
+{
+       unsigned long root_nr;
+       struct mem_section* root;
+
+       for (root_nr = 0;
+            root_nr < NR_MEM_SECTIONS;
+            root_nr += SECTIONS_PER_ROOT) {
+               root = __nr_to_section(root_nr);
+
+               if (!root)
+                       continue;
+
+               if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
+                    break;
+       }
+
+       return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
+}
+
 /* Record a memory area against a node. */
 void memory_present(int nid, unsigned long start, unsigned long end)
 {