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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 B5A16C6778F for ; Wed, 25 Jul 2018 16:29:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4B020204EC for ; Wed, 25 Jul 2018 16:29:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4B020204EC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zoho.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729355AbeGYRmR (ORCPT ); Wed, 25 Jul 2018 13:42:17 -0400 Received: from sender-pp-092.zoho.com ([135.84.80.237]:25494 "EHLO sender-pp-092.zoho.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728542AbeGYRmR (ORCPT ); Wed, 25 Jul 2018 13:42:17 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=zapps768; d=zoho.com; h=from:to:cc:subject:date:message-id:in-reply-to:references; b=fCbn3xBrPGxPROX/ClekHXzJkXfrE4ajrGtdYSk1LZREq7bPBZZrY7aAMGrMuv1/aN26qqtcFhWE 23z6YdEM3mk6JqEjjQDOvfK55UQakHM29TgRdF6i5B2p71bCQnih Received: from YEHS1XR956R00D1.lenovo.com (114.245.13.10 [114.245.13.10]) by mx.zohomail.com with SMTPS id 1532536166941927.3898531496442; Wed, 25 Jul 2018 09:29:26 -0700 (PDT) From: Huaisheng Ye To: linux-nvdimm@lists.01.org, dan.j.williams@intel.com Cc: ross.zwisler@linux.intel.com, willy@infradead.org, vishal.l.verma@intel.com, dave.jiang@intel.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, viro@zeniv.linux.org.uk, martin.petersen@oracle.com, axboe@kernel.dk, gregkh@linuxfoundation.org, bart.vanassche@wdc.com, jack@suse.cz, agk@redhat.com, snitzer@redhat.com, dm-devel@redhat.com, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, linux-fsdevel@vger.kernel.org, chengnt@lenovo.com, colyli@suse.de, Huaisheng Ye Subject: [PATCH v2 2/6] s390, dcssblk: kaddr and pfn can be NULL to ->direct_access() Date: Thu, 26 Jul 2018 00:28:45 +0800 Message-Id: <20180725162849.8320-3-yehs2007@zoho.com> X-Mailer: git-send-email 2.17.0.windows.1 In-Reply-To: <20180725162849.8320-1-yehs2007@zoho.com> References: <20180725162849.8320-1-yehs2007@zoho.com> X-ZohoMailClient: External Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Huaisheng Ye dcssblk_direct_access() needs to check the validity of pointers kaddr and pfn for NULL assignment. If anyone equals to NULL, it doesn't need to calculate the value. If either of them is equal to NULL, that is to say callers may have no need for kaddr or pfn, so this patch is prepared for allowing them to pass in NULL instead of having to pass in a pointer or local variable that they then just throw away. Signed-off-by: Huaisheng Ye --- drivers/s390/block/dcssblk.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c index ed60728..23e526c 100644 --- a/drivers/s390/block/dcssblk.c +++ b/drivers/s390/block/dcssblk.c @@ -922,9 +922,11 @@ static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show, unsigned long dev_sz; dev_sz = dev_info->end - dev_info->start + 1; - *kaddr = (void *) dev_info->start + offset; - *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset), - PFN_DEV|PFN_SPECIAL); + if (kaddr) + *kaddr = (void *) dev_info->start + offset; + if (pfn) + *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset), + PFN_DEV|PFN_SPECIAL); return (dev_sz - offset) / PAGE_SIZE; } -- 1.8.3.1