linux-kernel - [patch 1/1] combine two adjacent mtrr region with the same type

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Date:	Thu, 9 Oct 2008 16:21:40 +0800
From:	"bibo mao" <bibo.mao@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	akpm@...ux-foundation.org
Subject: [patch 1/1] combine two adjacent mtrr region with the same type

This patch is to combine two adjacent mtrr region with the same type.

 kernel/cpu/mtrr/main.c          |   17 +++++++++++++++--
 3 files changed, 15 insertions(+), 2 deletions(-)

Signed-off-by: bibo mao <bibo.mao@...il.com>

-------------------------------------------------------------------------------
diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c
index 6e212f3..c3adf83 100644
--- a/arch/x86/kernel/cpu/mtrr/main.c
+++ b/arch/x86/kernel/cpu/mtrr/main.c
@@ -305,7 +305,7 @@ int mtrr_add_page(unsigned long base, unsigned long size,
 {
 	int i, j, replace, error;
 	mtrr_type ltype;
-	unsigned long lbase, lsize;
+	unsigned long lbase, lsize, newbase;

 	if (!mtrr_if)
 		return -ENXIO;
@@ -344,7 +344,7 @@ int mtrr_add_page(unsigned long base, unsigned long size,
 	mutex_lock(&mtrr_mutex);
 	for (i = 0; i < num_var_ranges; ++i) {
 		mtrr_if->get(i, &lbase, &lsize, &ltype);
-		if (!lsize || base > lbase + lsize - 1 || base + size - 1 < lbase)
+		if (!lsize || base > lbase + lsize || base + size < lbase)
 			continue;
 		/*  At this point we know there is some kind of overlap/enclosure  */
 		if (base < lbase || base + size - 1 > lbase + lsize - 1) {
@@ -356,6 +356,19 @@ int mtrr_add_page(unsigned long base, unsigned long size,
 				}
 				else if (types_compatible(type, ltype))
 					continue;
+			} else if ((base == lbase + lsize) || (lbase ==base + size)) {
+				if (type != ltype)
+					continue;
+				/* New region adjacent with an existing region  */
+				newbase = (base < lbase) ? base : lbase;
+				if (!mtrr_if->validate_add_page(newbase,lsize + size,type) &&
+				   mtrr_if->get_free_region(newbase, lsize + size, replace)>=0) {
+					base = newbase;
+					size += lsize;
+					replace = i;
+					continue;
+				} else
+					continue;
 			}
 			printk(KERN_WARNING
 			       "mtrr: 0x%lx000,0x%lx000 overlaps existing"
--
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