From c4f0e9dee326ca7c75574a623a5115ad1e6df13c Mon Sep 17 00:00:00 2001
From: Venki Pallipadi <venkatesh.pallipadi@intel.com>
Date: Tue, 19 Aug 2008 16:28:01 -0700
Subject: [PATCH] --- yaml --- r: 109031 b: refs/heads/master c:
 80c5e73d6028e0f03ab0c70e7c4cbf98ac2e0c43 h: refs/heads/master i:   109029:
 93519b3632e02942e76a3b1b24425a2dea7c1ae0   109027:
 2f1bf7fc3dce2a229869eccc33d61f26a9f864d2   109023:
 700dec3672591b65cb01e113fa84442b39dcc9c0 v: v3

---
 [refs]                  |  2 +-
 trunk/arch/x86/mm/pat.c | 33 +++++++++++++++++++++++++++++++--
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/[refs] b/[refs]
index 901c4e6c507e..af40363e52aa 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: c6744955d0ec0cb485c28c51eeb7185e260f6172
+refs/heads/master: 80c5e73d6028e0f03ab0c70e7c4cbf98ac2e0c43
diff --git a/trunk/arch/x86/mm/pat.c b/trunk/arch/x86/mm/pat.c
index 2fe30916d4b6..bb6e8a267bfe 100644
--- a/trunk/arch/x86/mm/pat.c
+++ b/trunk/arch/x86/mm/pat.c
@@ -207,6 +207,9 @@ static int chk_conflict(struct memtype *new, struct memtype *entry,
 	return -EBUSY;
 }
 
+static struct memtype *cached_entry;
+static u64 cached_start;
+
 /*
  * req_type typically has one of the:
  * - _PAGE_CACHE_WB
@@ -280,11 +283,17 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
 
 	spin_lock(&memtype_lock);
 
+	if (cached_entry && start >= cached_start)
+		entry = cached_entry;
+	else
+		entry = list_entry(&memtype_list, struct memtype, nd);
+
 	/* Search for existing mapping that overlaps the current range */
 	where = NULL;
-	list_for_each_entry(entry, &memtype_list, nd) {
+	list_for_each_entry_continue(entry, &memtype_list, nd) {
 		if (end <= entry->start) {
 			where = entry->nd.prev;
+			cached_entry = list_entry(where, struct memtype, nd);
 			break;
 		} else if (start <= entry->start) { /* end > entry->start */
 			err = chk_conflict(new, entry, new_type);
@@ -292,6 +301,8 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
 				dprintk("Overlap at 0x%Lx-0x%Lx\n",
 					entry->start, entry->end);
 				where = entry->nd.prev;
+				cached_entry = list_entry(where,
+							struct memtype, nd);
 			}
 			break;
 		} else if (start < entry->end) { /* start > entry->start */
@@ -299,7 +310,20 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
 			if (!err) {
 				dprintk("Overlap at 0x%Lx-0x%Lx\n",
 					entry->start, entry->end);
-				where = &entry->nd;
+				cached_entry = list_entry(entry->nd.prev,
+							struct memtype, nd);
+
+				/*
+				 * Move to right position in the linked
+				 * list to add this new entry
+				 */
+				list_for_each_entry_continue(entry,
+							&memtype_list, nd) {
+					if (start <= entry->start) {
+						where = entry->nd.prev;
+						break;
+					}
+				}
 			}
 			break;
 		}
@@ -314,6 +338,8 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
 		return err;
 	}
 
+	cached_start = start;
+
 	if (where)
 		list_add(&new->nd, where);
 	else
@@ -343,6 +369,9 @@ int free_memtype(u64 start, u64 end)
 	spin_lock(&memtype_lock);
 	list_for_each_entry(entry, &memtype_list, nd) {
 		if (entry->start == start && entry->end == end) {
+			if (cached_entry == entry || cached_start == start)
+				cached_entry = NULL;
+
 			list_del(&entry->nd);
 			kfree(entry);
 			err = 0;