From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932221AbcGKVRG (ORCPT ); Mon, 11 Jul 2016 17:17:06 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:43158 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751157AbcGKVRE (ORCPT ); Mon, 11 Jul 2016 17:17:04 -0400 Date: Mon, 11 Jul 2016 14:17:02 -0700 From: Andrew Morton To: chengang@emindsoft.com.cn 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 Message-Id: <20160711141702.fb1879707aa2bcb290133a43@linux-foundation.org> In-Reply-To: <1468084625-26999-1-git-send-email-chengang@emindsoft.com.cn> References: <1468084625-26999-1-git-send-email-chengang@emindsoft.com.cn> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.