linux-kernel - [tip:x86/urgent] range: Do not add new blank slot with add_range_with

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Message-ID: <tip-0541881502a1276149889fe468662ff6a8fc8f6d@git.kernel.org>
Date:	Tue, 18 Jun 2013 09:52:11 -0700
From:	tip-bot for Yinghai Lu <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	yinghai@...nel.org, joshuacov@...glemail.com, tglx@...utronix.de,
	hpa@...ux.intel.com
Subject: [tip:x86/urgent] range:
  Do not add new blank slot with add_range_with_merge

Commit-ID:  0541881502a1276149889fe468662ff6a8fc8f6d
Gitweb:     http://git.kernel.org/tip/0541881502a1276149889fe468662ff6a8fc8f6d
Author:     Yinghai Lu <yinghai@...nel.org>
AuthorDate: Thu, 13 Jun 2013 13:17:02 -0700
Committer:  H. Peter Anvin <hpa@...ux.intel.com>
CommitDate: Tue, 18 Jun 2013 11:32:10 -0500

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@...glemail.com>
Tested-by: Joshua Covington <joshuacov@...glemail.com>
Signed-off-by: Yinghai Lu <yinghai@...nel.org>
Link: http://lkml.kernel.org/r/1371154622-8929-3-git-send-email-yinghai@kernel.org
Cc: <stable@...r.kernel.org> v3.9
Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
---
 kernel/range.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/kernel/range.c b/kernel/range.c
index eb911db..322ea8e 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: */
--
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