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>

4 files changed, 52 insertions, 30 deletions

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 71ea92319241..6187a8567bc7 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -110,9 +110,6 @@ extern int allocate_resource(struct resource *root, struct resource *new,
 int adjust_resource(struct resource *res, resource_size_t start,
                     resource_size_t size);
 
-/* get registered SYSTEM_RAM resources in specified area */
-extern int find_next_system_ram(struct resource *res);
-
 /* Convenience shorthand with allocation */
 #define request_region(start,n,name)    __request_region(&ioport_resource, (start), (n), (name))
 #define request_mem_region(start,n,name) __request_region(&iomem_resource, (start), (n), (name))
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index b573d1ec871f..0a14dad95453 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -63,6 +63,14 @@ extern int online_pages(unsigned long, unsigned long);
 extern int __add_pages(struct zone *zone, unsigned long start_pfn,
         unsigned long nr_pages);
 
+/*
+ * Walk thorugh all memory which is registered as resource.
+ * arg is (start_pfn, nr_pages, private_arg_pointer)
+ */
+extern int walk_memory_resource(unsigned long start_pfn,
+                        unsigned long nr_pages, void *arg,
+                        int (*func)(unsigned long, unsigned long, void *));
+
 #ifdef CONFIG_NUMA
 extern int memory_add_physaddr_to_nid(u64 start);
 #else
diff --git a/kernel/resource.c b/kernel/resource.c
index 9bd14fd3e6de..a358142ff48f 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -234,7 +234,7 @@ EXPORT_SYMBOL(release_resource);
  * the caller must specify res->start, res->end, res->flags.
  * If found, returns 0, res is overwritten, if not found, returns -1.
  */
-int find_next_system_ram(struct resource *res)
+static int find_next_system_ram(struct resource *res)
 {
         resource_size_t start, end;
         struct resource *p;
@@ -267,6 +267,30 @@ int find_next_system_ram(struct resource *res)
                 res->end = p->end;
         return 0;
 }
+int
+walk_memory_resource(unsigned long start_pfn, unsigned long nr_pages, void *arg,
+                        int (*func)(unsigned long, unsigned long, void *))
+{
+        struct resource res;
+        unsigned long pfn, len;
+        u64 orig_end;
+        int ret = -1;
+        res.start = (u64) start_pfn << PAGE_SHIFT;
+        res.end = ((u64)(start_pfn + nr_pages) << PAGE_SHIFT) - 1;
+        res.flags = IORESOURCE_MEM;
+        orig_end = res.end;
+        while ((res.start < res.end) && (find_next_system_ram(&res) >= 0)) {
+                pfn = (unsigned long)(res.start >> PAGE_SHIFT);
+                len = (unsigned long)((res.end + 1 - res.start) >> PAGE_SHIFT);
+                ret = (*func)(pfn, len, arg);
+                if (ret)
+                        break;
+                res.start = res.end + 1;
+                res.end = orig_end;
+        }
+        return ret;
+}
+
 #endif
 
 /*
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9c12ae5e3695..1cbe9579e233 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;