linux-kernel - [Resend PATCH] x86/e820: break the loop when the region is less then current region

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Message-Id: <20170127024724.38506-1-richard.weiyang@gmail.com>
Date:   Fri, 27 Jan 2017 10:47:24 +0800
From:   Wei Yang <richard.weiyang@...il.com>
To:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Wei Yang <richard.weiyang@...il.com>
Subject: [Resend PATCH] x86/e820: break the loop when the region is less then current region

e820_all_mapped() iterates the e820 table to check whether a region is
mapped or not. Since the e820 table is sorted, when the region is less than
the current region, no need to continue the iteration.

The patch breaks the loop accordingly.

Signed-off-by: Wei Yang <richard.weiyang@...il.com>
---
 arch/x86/kernel/e820.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 90e8dde..f4fb197 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -86,10 +86,16 @@ int __init e820_all_mapped(u64 start, u64 end, unsigned type)
 	for (i = 0; i < e820->nr_map; i++) {
 		struct e820entry *ei = &e820->map[i];
 
+		/* Since the e820 table is sorted, when the region is less
+		 * than the current region, break it.
+		 */
+		if (ei->addr >= end)
+			break;
+
 		if (type && ei->type != type)
 			continue;
 		/* is the region (part) in overlap with the current region ?*/
-		if (ei->addr >= end || ei->addr + ei->size <= start)
+		if (ei->addr + ei->size <= start)
 			continue;
 
 		/* if the region is at the beginning of <start,end> we move
-- 
2.5.0