From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753399AbcGLRC2 (ORCPT ); Tue, 12 Jul 2016 13:02:28 -0400 Received: from out1134-202.mail.aliyun.com ([42.120.134.202]:13299 "EHLO out1134-202.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750874AbcGLRC0 (ORCPT ); Tue, 12 Jul 2016 13:02:26 -0400 X-Greylist: delayed 319 seconds by postgrey-1.27 at vger.kernel.org; Tue, 12 Jul 2016 13:02:26 EDT X-Alimail-AntiSpam: AC=CONTINUE;BC=0.08217455|-1;FP=0|0|0|0|0|-1|-1|-1;HT=e02c03295;MF=chengang@emindsoft.com.cn;NM=1;PH=DS;RN=16;RT=16;SR=0;TI=SMTPD_----50YQbp3_1468342610; Message-ID: <578522CE.9060905@emindsoft.com.cn> Date: Wed, 13 Jul 2016 01:03:10 +0800 From: Chen Gang User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Andrew Morton CC: vbabka@suse.cz, mhocko@suse.com, kirill.shutemov@linux.intel.com, mingo@kernel.org, dave.hansen@linux.intel.com, dan.j.williams@intel.com, hannes@cmpxchg.org, jack@suse.cz, iamjoonsoo.kim@lge.com, jmarchan@redhat.com, dingel@linux.vnet.ibm.com, oleg@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Chen Gang Subject: Re: [PATCH] mm: gup: Re-define follow_page_mask output parameter page_mask usage References: <1468084625-26999-1-git-send-email-chengang@emindsoft.com.cn> <20160711141702.fb1879707aa2bcb290133a43@linux-foundation.org> In-Reply-To: <20160711141702.fb1879707aa2bcb290133a43@linux-foundation.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/12/16 05:17, Andrew Morton wrote: > On Sun, 10 Jul 2016 01:17:05 +0800 chengang@emindsoft.com.cn wrote: > >> For a pure output parameter: >> >> - When callee fails, the caller should not assume the output parameter >> is still valid. >> >> - And callee should not assume the pure output parameter must be >> provided by caller -- caller has right to pass NULL when caller does >> not care about it. > > Sorry, I don't think this one is worth merging really. > OK, thanks, I can understand. It will be better if provide more details: e.g. - This patch is incorrect, or the comments is not correct. - The patch is worthless, at present. - ... By the way, this patch let the callee keep the output parameter no touch if callee no additional outputs, callee assumes caller has initialized the output parameter (for me, it is OK, there are many cases like this). Thanks. -- Chen Gang (陈刚) Managing Natural Environments is the Duty of Human Beings.