From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D808AC432C1 for ; Tue, 24 Sep 2019 00:30:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AC13820820 for ; Tue, 24 Sep 2019 00:30:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2503634AbfIXAaE (ORCPT ); Mon, 23 Sep 2019 20:30:04 -0400 Received: from mga02.intel.com ([134.134.136.20]:63376 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2503566AbfIXAaE (ORCPT ); Mon, 23 Sep 2019 20:30:04 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 23 Sep 2019 17:30:03 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,542,1559545200"; d="scan'208";a="195529558" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by FMSMGA003.fm.intel.com with ESMTP; 23 Sep 2019 17:30:02 -0700 Date: Tue, 24 Sep 2019 08:29:43 +0800 From: Wei Yang To: Peter Zijlstra Cc: Wei Yang , dave.hansen@linux.intel.com, luto@kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] x86/mm: replace a goto by merging two if clause Message-ID: <20190924002942.GA1813@richard> Reply-To: Wei Yang References: <20190919020844.27461-1-richardw.yang@linux.intel.com> <20190919020844.27461-2-richardw.yang@linux.intel.com> <20190923092231.GJ2349@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190923092231.GJ2349@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 23, 2019 at 11:22:31AM +0200, Peter Zijlstra wrote: >On Thu, Sep 19, 2019 at 10:08:44AM +0800, Wei Yang wrote: >> There is only one place to use good_area jump, which could be reduced by >> merging the following two if clause. >> >> Signed-off-by: Wei Yang >> --- >> arch/x86/mm/fault.c | 11 +++++------ >> 1 file changed, 5 insertions(+), 6 deletions(-) >> >> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c >> index 9d18b73b5f77..72ce6c69e195 100644 >> --- a/arch/x86/mm/fault.c >> +++ b/arch/x86/mm/fault.c >> @@ -1390,18 +1390,17 @@ void do_user_addr_fault(struct pt_regs *regs, >> vma = find_vma(mm, address); >> if (unlikely(!vma)) >> goto bad_area; >> - if (likely(vma->vm_start <= address)) >> - goto good_area; >> - if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) >> - goto bad_area; >> - if (unlikely(expand_stack(vma, address))) >> + if (likely(vma->vm_start <= address)) { >> + /* good area, do nothing */ >> + } else if (unlikely(!(vma->vm_flags & VM_GROWSDOWN)) || >> + unlikely(expand_stack(vma, address))) { >> goto bad_area; >> + } >> >> /* >> * Ok, we have a good vm_area for this memory access, so >> * we can handle it.. >> */ >> -good_area: >> if (unlikely(access_error(hw_error_code, vma))) { >> bad_area_access_error(regs, hw_error_code, address, vma); >> return; > >I find the old code far easier to read... is there any actual reason to >do this? No, just want to make it easy to read. -- Wei Yang Help you, Help me