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, 25 insertions, 1 deletions

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
 
 /*