Return-Path: Received: from mail113-249.mail.alibaba.com ([205.204.113.249]:55992 "EHLO us-alimail-mta2.hst.scl.en.alidc.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751308AbbLMJJs (ORCPT ); Sun, 13 Dec 2015 04:09:48 -0500 Message-ID: <566D3662.6080804@emindsoft.com.cn> Date: Sun, 13 Dec 2015 17:12:02 +0800 From: Chen Gang MIME-Version: 1.0 Subject: [PATCH] include/asm-generic/pgtable.h: Check once and return for pgprot_modify Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: arnd@arndb.de, Andrew Morton Cc: Linux-Arch , "linux-kernel@vger.kernel.org" , Chen Gang , chenwei@emindsoft.com.cn Message-ID: <20151213091202.MhiJeuuBeP86wixW1ClvZX8sI53oFT8lvDyr-P0cjgI@z> pgprot_val() likes an empty operation, and all three checking statements are related with oldprot, so only check once is enough, the reason is: - if both "oldprot == pgprot_noncached(oldprot)" and "oldprot == pgprot_writecombine(oldprot)" are satisfied. - So "pgprot_noncached(oldprot) == pgprot_writecombine(oldprot)", too. - So as the result, it is still equal to check once (for pgprot_device can get the same result). Then can return directly. Signed-off-by: Chen Gang --- include/asm-generic/pgtable.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 069536a..cd9e7c4 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -306,11 +306,11 @@ static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b) static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot) { if (pgprot_val(oldprot) == pgprot_val(pgprot_noncached(oldprot))) - newprot = pgprot_noncached(newprot); + return pgprot_noncached(newprot); if (pgprot_val(oldprot) == pgprot_val(pgprot_writecombine(oldprot))) - newprot = pgprot_writecombine(newprot); + return pgprot_writecombine(newprot); if (pgprot_val(oldprot) == pgprot_val(pgprot_device(oldprot))) - newprot = pgprot_device(newprot); + return pgprot_device(newprot); return newprot; } #endif -- 1.9.3