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, URIBL_BLOCKED,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 5AD06C433E0 for ; Tue, 7 Jul 2020 11:45:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 40FFE206F6 for ; Tue, 7 Jul 2020 11:45:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728530AbgGGLpp (ORCPT ); Tue, 7 Jul 2020 07:45:45 -0400 Received: from mx2.suse.de ([195.135.220.15]:49424 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728318AbgGGLpo (ORCPT ); Tue, 7 Jul 2020 07:45:44 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 85156AE35; Tue, 7 Jul 2020 11:45:43 +0000 (UTC) Subject: Re: [PATCH v2 1/3] xen/privcmd: Corrected error handling path To: Souptick Joarder Cc: Boris Ostrovsky , sstabellini@kernel.org, xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, John Hubbard , Paul Durrant References: <1594059372-15563-1-git-send-email-jrdr.linux@gmail.com> <1594059372-15563-2-git-send-email-jrdr.linux@gmail.com> <4bafb184-6f07-2582-3d0f-86fb53dd30dc@suse.com> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Message-ID: <7208d7fe-8822-8e9b-e531-05238ece0b02@suse.com> Date: Tue, 7 Jul 2020 13:45:42 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07.07.20 13:40, Souptick Joarder wrote: > On Tue, Jul 7, 2020 at 3:05 PM Jürgen Groß wrote: >> >> On 06.07.20 20:16, Souptick Joarder wrote: >>> Previously, if lock_pages() end up partially mapping pages, it used >>> to return -ERRNO due to which unlock_pages() have to go through >>> each pages[i] till *nr_pages* to validate them. This can be avoided >>> by passing correct number of partially mapped pages & -ERRNO separately, >>> while returning from lock_pages() due to error. >>> >>> With this fix unlock_pages() doesn't need to validate pages[i] till >>> *nr_pages* for error scenario and few condition checks can be ignored. >>> >>> Signed-off-by: Souptick Joarder >>> Cc: John Hubbard >>> Cc: Boris Ostrovsky >>> Cc: Paul Durrant >>> --- >>> drivers/xen/privcmd.c | 31 +++++++++++++++---------------- >>> 1 file changed, 15 insertions(+), 16 deletions(-) >>> >>> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c >>> index a250d11..33677ea 100644 >>> --- a/drivers/xen/privcmd.c >>> +++ b/drivers/xen/privcmd.c >>> @@ -580,13 +580,13 @@ static long privcmd_ioctl_mmap_batch( >>> >>> static int lock_pages( >>> struct privcmd_dm_op_buf kbufs[], unsigned int num, >>> - struct page *pages[], unsigned int nr_pages) >>> + struct page *pages[], unsigned int nr_pages, unsigned int *pinned) >>> { >>> unsigned int i; >>> + int page_count = 0; >> >> Initial value shouldn't be needed, and ... >> >>> >>> for (i = 0; i < num; i++) { >>> unsigned int requested; >>> - int pinned; >> >> ... you could move the declaration here. >> >> With that done you can add my >> >> Reviewed-by: Juergen Gross > > Ok. But does it going make any difference other than limiting scope ? Dropping the initializer surely does, and in the end page_count just replaces the former pinned variable, so why would we want to widen the scope with this patch? Juergen