range: Do not add new blank slot with add_range_with_merge

Joshua reported: Commit cd7b304dfaf1 (x86, range: fix missing merge
during add range) broke mtrr cleanup on his setup in 3.9.5.
corresponding commit in upstream is fbe06b7bae7c.

The reason is add_range_with_merge could generate blank spot.

We could avoid that by searching new expanded start/end, that
new range should include all connected ranges in range array.
At last add the new expanded start/end to the range array.
Also move up left array so do not add new blank slot in the
range array.

-v2: move left array to avoid enhance add_range()
-v3: include fix from Joshua about memmove declaring when
     DYN_DEBUG is used.

Reported-by: Joshua Covington <joshuacov@googlemail.com>
Tested-by: Joshua Covington <joshuacov@googlemail.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1371154622-8929-3-git-send-email-yinghai@kernel.org
Cc: <stable@vger.kernel.org> v3.9
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 11 insertions, 10 deletions

diff --git a/kernel/range.c b/kernel/range.c
index eb911dbce267..322ea8e93e4b 100644
--- a/kernel/range.c
+++ b/kernel/range.c
@@ -4,7 +4,7 @@
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/sort.h>
-
+#include <linux/string.h>
 #include <linux/range.h>
 
 int add_range(struct range *range, int az, int nr_range, u64 start, u64 end)
@@ -32,9 +32,8 @@ int add_range_with_merge(struct range *range, int az, int nr_range,
         if (start >= end)
                 return nr_range;
 
-        /* Try to merge it with old one: */
+        /* get new start/end: */
         for (i = 0; i < nr_range; i++) {
-                u64 final_start, final_end;
                 u64 common_start, common_end;
 
                 if (!range[i].end)
@@ -45,14 +44,16 @@ int add_range_with_merge(struct range *range, int az, int nr_range,
                 if (common_start > common_end)
                         continue;
 
-                final_start = min(range[i].start, start);
-                final_end = max(range[i].end, end);
+                /* new start/end, will add it back at last */
+                start = min(range[i].start, start);
+                end = max(range[i].end, end);
 
-                /* clear it and add it back for further merge */
-                range[i].start = 0;
-                range[i].end =  0;
-                return add_range_with_merge(range, az, nr_range,
-                        final_start, final_end);
+                memmove(&range[i], &range[i + 1],
+                        (nr_range - (i + 1)) * sizeof(range[i]));
+                range[nr_range - 1].start = 0;
+                range[nr_range - 1].end   = 0;
+                nr_range--;
+                i--;
         }
 
         /* Need to add it: */