linux-kernel - [PATCH] mm/mmap.c: Change static function __install_special

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Date:	Sun, 4 Oct 2015 04:02:09 +0800
From:	Chen Gang <xili_gchen_5257@...mail.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	"kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
	"riel@...hat.com" <riel@...hat.com>,
	"oleg@...hat.com" <oleg@...hat.com>, Michal Hocko <mhocko@...e.cz>,
	"dave@...olabs.net" <dave@...olabs.net>,
	"pfeiner@...gle.com" <pfeiner@...gle.com>,
	"aarcange@...hat.com" <aarcange@...hat.com>,
	"vishnu.ps@...sung.com" <vishnu.ps@...sung.com>
CC:	Linux Memory <linux-mm@...ck.org>,
	kernel mailing list <linux-kernel@...r.kernel.org>
Subject: [PATCH] mm/mmap.c: Change static function __install_special_mapping
 args' order

>From 5a6ffe3515c21d1152586e484c29fed91d2b0b6f Mon Sep 17 00:00:00 2001
From: Chen Gang <gang.chen.5i5j@...il.com>
Date: Sun, 4 Oct 2015 03:47:24 +0800
Subject: [PATCH] mm/mmap.c: Change static function __install_special_mapping args' order

Let __install_special_mapping() args order match the caller, so the
caller can pass their register args directly to callee with no touch.

For most of architectures, args (at least the first 5th args) are in
registers, so this change will have effect on most of architectures.

For -O2, __install_special_mapping() may be inlined under most of
architectures, but for -Os, it should not. So this change can get a
little better performance for -Os, at least.

Signed-off-by: Chen Gang <gang.chen.5i5j@...il.com>
---
 mm/mmap.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index f7c1631..98ff62d 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3048,8 +3048,8 @@ static int special_mapping_fault(struct vm_area_struct *vma,
 static struct vm_area_struct *__install_special_mapping(
 	struct mm_struct *mm,
 	unsigned long addr, unsigned long len,
-	unsigned long vm_flags, const struct vm_operations_struct *ops,
-	void *priv)
+	unsigned long vm_flags, void *priv,
+	const struct vm_operations_struct *ops)
 {
 	int ret;
 	struct vm_area_struct *vma;
@@ -3098,8 +3098,8 @@ struct vm_area_struct *_install_special_mapping(
 	unsigned long addr, unsigned long len,
 	unsigned long vm_flags, const struct vm_special_mapping *spec)
 {
-	return __install_special_mapping(mm, addr, len, vm_flags,
-					 &special_mapping_vmops, (void *)spec);
+	return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
+					&special_mapping_vmops);
 }
 
 int install_special_mapping(struct mm_struct *mm,
@@ -3107,8 +3107,8 @@ int install_special_mapping(struct mm_struct *mm,
 			    unsigned long vm_flags, struct page **pages)
 {
 	struct vm_area_struct *vma = __install_special_mapping(
-		mm, addr, len, vm_flags, &legacy_special_mapping_vmops,
-		(void *)pages);
+		mm, addr, len, vm_flags, (void *)pages,
+		&legacy_special_mapping_vmops);
 
 	return PTR_ERR_OR_ZERO(vma);
 }
-- 
1.9.3 		 	   		  
Download attachment "0001-mm-mmap.c-Change-static-function-__install_special_m.patch" of type "application/octet-stream" (2177 bytes)