x86_64: extract helper function from e820_register_active_regions

The logic in e820_find_active_regions() for determining the true active
regions for an e820 entry given a range of PFN's is needed for
e820_hole_size() as well.

e820_hole_size() is called from the NUMA emulation code to determine the
reserved area within an address range on a per-node basis.  Its logic should
duplicate that of finding active regions in an e820 entry because these are
the only true ranges we may register anyway.

[akpm@linux-foundation.org: cleanup]
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/x86_64/kernel/e820.c b/arch/x86_64/kernel/e820.c
index 13c6c37610e029978e13f829018600b21ed5ca42..2570643ba1c51fdbf3cbc19034f8baabc9b28607 100644 (file)
--- a/arch/x86_64/kernel/e820.c
+++ b/arch/x86_64/kernel/e820.c
@@ -289,47 +289,61 @@ void __init e820_mark_nosave_regions(void)
        }
 }
 
-/* Walk the e820 map and register active regions within a node */
-void __init
-e820_register_active_regions(int nid, unsigned long start_pfn,
-                                                       unsigned long end_pfn)
+/*
+ * Finds an active region in the address range from start_pfn to end_pfn and
+ * returns its range in ei_startpfn and ei_endpfn for the e820 entry.
+ */
+static int __init e820_find_active_region(const struct e820entry *ei,
+                                         unsigned long start_pfn,
+                                         unsigned long end_pfn,
+                                         unsigned long *ei_startpfn,
+                                         unsigned long *ei_endpfn)
 {
-       int i;
-       unsigned long ei_startpfn, ei_endpfn;
-       for (i = 0; i < e820.nr_map; i++) {
-               struct e820entry *ei = &e820.map[i];
-               ei_startpfn = round_up(ei->addr, PAGE_SIZE) >> PAGE_SHIFT;
-               ei_endpfn = round_down(ei->addr + ei->size, PAGE_SIZE)
-                                                               >> PAGE_SHIFT;
+       *ei_startpfn = round_up(ei->addr, PAGE_SIZE) >> PAGE_SHIFT;
+       *ei_endpfn = round_down(ei->addr + ei->size, PAGE_SIZE) >> PAGE_SHIFT;
 
-               /* Skip map entries smaller than a page */
-               if (ei_startpfn >= ei_endpfn)
-                       continue;
+       /* Skip map entries smaller than a page */
+       if (*ei_startpfn >= *ei_endpfn)
+               return 0;
 
-               /* Check if end_pfn_map should be updated */
-               if (ei->type != E820_RAM && ei_endpfn > end_pfn_map)
-                       end_pfn_map = ei_endpfn;
+       /* Check if end_pfn_map should be updated */
+       if (ei->type != E820_RAM && *ei_endpfn > end_pfn_map)
+               end_pfn_map = *ei_endpfn;
 
-               /* Skip if map is outside the node */
-               if (ei->type != E820_RAM ||
-                               ei_endpfn <= start_pfn ||
-                               ei_startpfn >= end_pfn)
-                       continue;
+       /* Skip if map is outside the node */
+       if (ei->type != E820_RAM || *ei_endpfn <= start_pfn ||
+                                   *ei_startpfn >= end_pfn)
+               return 0;
 
-               /* Check for overlaps */
-               if (ei_startpfn < start_pfn)
-                       ei_startpfn = start_pfn;
-               if (ei_endpfn > end_pfn)
-                       ei_endpfn = end_pfn;
+       /* Check for overlaps */
+       if (*ei_startpfn < start_pfn)
+               *ei_startpfn = start_pfn;
+       if (*ei_endpfn > end_pfn)
+               *ei_endpfn = end_pfn;
 
-               /* Obey end_user_pfn to save on memmap */
-               if (ei_startpfn >= end_user_pfn)
-                       continue;
-               if (ei_endpfn > end_user_pfn)
-                       ei_endpfn = end_user_pfn;
+       /* Obey end_user_pfn to save on memmap */
+       if (*ei_startpfn >= end_user_pfn)
+               return 0;
+       if (*ei_endpfn > end_user_pfn)
+               *ei_endpfn = end_user_pfn;
 
-               add_active_range(nid, ei_startpfn, ei_endpfn);
-       }
+       return 1;
+}
+
+/* Walk the e820 map and register active regions within a node */
+void __init
+e820_register_active_regions(int nid, unsigned long start_pfn,
+                                                       unsigned long end_pfn)
+{
+       unsigned long ei_startpfn;
+       unsigned long ei_endpfn;
+       int i;
+
+       for (i = 0; i < e820.nr_map; i++)
+               if (e820_find_active_region(&e820.map[i],
+                                           start_pfn, end_pfn,
+                                           &ei_startpfn, &ei_endpfn))
+                       add_active_range(nid, ei_startpfn, ei_endpfn);
 }
 
 /*