memory unplug: memory hotplug cleanup

A clean up patch for "scanning memory resource [start, end)" operation.

Now, find_next_system_ram() function is used in memory hotplug, but this
interface is not easy to use and codes are complicated.

This patch adds walk_memory_resouce(start,len,arg,func) function.
The function 'func' is called per valid memory resouce range in [start,pfn).

[pbadari@us.ibm.com: Error handling in walk_memory_resource()]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 19 insertions, 26 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9c12ae5e369..1cbe9579e23 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -161,14 +161,27 @@ static void grow_pgdat_span(struct pglist_data *pgdat,
                                         pgdat->node_start_pfn;
 }
 
-int online_pages(unsigned long pfn, unsigned long nr_pages)
+static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
+                        void *arg)
 {
         unsigned long i;
+        unsigned long onlined_pages = *(unsigned long *)arg;
+        struct page *page;
+        if (PageReserved(pfn_to_page(start_pfn)))
+                for (i = 0; i < nr_pages; i++) {
+                        page = pfn_to_page(start_pfn + i);
+                        online_page(page);
+                        onlined_pages++;
+                }
+        *(unsigned long *)arg = onlined_pages;
+        return 0;
+}
+
+
+int online_pages(unsigned long pfn, unsigned long nr_pages)
+{
         unsigned long flags;
         unsigned long onlined_pages = 0;
-        struct resource res;
-        u64 section_end;
-        unsigned long start_pfn;
         struct zone *zone;
         int need_zonelists_rebuild = 0;
 
@@ -191,28 +204,8 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
         if (!populated_zone(zone))
                 need_zonelists_rebuild = 1;
 
-        res.start = (u64)pfn << PAGE_SHIFT;
-        res.end = res.start + ((u64)nr_pages << PAGE_SHIFT) - 1;
-        res.flags = IORESOURCE_MEM; /* we just need system ram */
-        section_end = res.end;
-
-        while ((res.start < res.end) && (find_next_system_ram(&res) >= 0)) {
-                start_pfn = (unsigned long)(res.start >> PAGE_SHIFT);
-                nr_pages = (unsigned long)
-                           ((res.end + 1 - res.start) >> PAGE_SHIFT);
-
-                if (PageReserved(pfn_to_page(start_pfn))) {
-                        /* this region's page is not onlined now */
-                        for (i = 0; i < nr_pages; i++) {
-                                struct page *page = pfn_to_page(start_pfn + i);
-                                online_page(page);
-                                onlined_pages++;
-                        }
-                }
-
-                res.start = res.end + 1;
-                res.end = section_end;
-        }
+        walk_memory_resource(pfn, nr_pages, &onlined_pages,
+                online_pages_range);
         zone->present_pages += onlined_pages;
         zone->zone_pgdat->node_present_pages += onlined_pages;