[PATCH] Optimize the resource overlap check

[Richard Yang <weiyang@linux.vnet.ibm.com>]

In coalesce_windows() it tries to check whether the res1 and res2 overlap.
This function do four comparisons, which could be done with one
comparisons.

Also make the resource_check_overlap() a common function for others.

Signed-Off-By: Wei Yang <weiyang@linux.vnet.ibm.com>
---
 arch/x86/pci/acpi.c    |   12 +-----------
 include/linux/ioport.h |    7 +++++++
 2 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
index 68c3c13..f2bb99e 100644
--- a/arch/x86/pci/acpi.c
+++ b/arch/x86/pci/acpi.c
@@ -181,13 +181,6 @@ setup_resource(struct acpi_resource *acpi_res, void *data)
 	return AE_OK;
 }

-static bool resource_contains(struct resource *res, resource_size_t point)
-{
-	if (res->start <= point && point <= res->end)
-		return true;
-	return false;
-}
-
 static void coalesce_windows(struct pci_root_info *info, unsigned long type)
 {
 	int i, j;
@@ -208,10 +201,7 @@ static void coalesce_windows(struct pci_root_info *info, unsigned long type)
 			 * our resources no longer match the ACPI _CRS, but
 			 * the kernel resource tree doesn't allow overlaps.
 			 */
-			if (resource_contains(res1, res2->start) ||
-			    resource_contains(res1, res2->end) ||
-			    resource_contains(res2, res1->start) ||
-			    resource_contains(res2, res1->end)) {
+			if (resource_check_overlap(res1, res2)) {
 				res1->start = min(res1->start, res2->start);
 				res1->end = max(res1->end, res2->end);
 				dev_info(&info->bridge->dev,
diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index e9bb22c..374259b 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -198,5 +198,12 @@ extern int
 walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 		void *arg, int (*func)(unsigned long, unsigned long, void *));

+static inline int resource_check_overlap(struct resource *r1,
+                                         struct resource *r2)
+{
+       return (r1->start <= r2->end && r1->end >= r2->start);
+}
+
+
 #endif /* __ASSEMBLY__ */
 #endif	/* _LINUX_IOPORT_H */
-- 
1.7.4.1

-- 
Richard Yang
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