From patchwork Mon Jul 30 07:15:44 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Huaisheng Ye X-Patchwork-Id: 10548559 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 298B4A754 for ; Mon, 30 Jul 2018 07:16:55 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1488529741 for ; Mon, 30 Jul 2018 07:16:55 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 08BAD29755; Mon, 30 Jul 2018 07:16:55 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9F91F29741 for ; Mon, 30 Jul 2018 07:16:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727094AbeG3IuX (ORCPT ); Mon, 30 Jul 2018 04:50:23 -0400 Received: from sender-pp-092.zoho.com ([135.84.80.237]:25438 "EHLO sender-pp-092.zoho.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726210AbeG3IuW (ORCPT ); Mon, 30 Jul 2018 04:50:22 -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=O8ywsKPHA4QkEojT1tTHWNbf3U3VAyBfKC1kAzUgKxpbgtMOCnav/i1b4Lv7B7TRSEaWuAdOOvn1 Rhhh9yuuVinC417TmprZYzjw+ZLr3Bg2DuFb0z6VQQxzTnegsUWN Received: from YEHS1XR956R00D1.lenovo.com (221.219.122.69 [221.219.122.69]) by mx.zohomail.com with SMTPS id 153293498037231.188860816768056; Mon, 30 Jul 2018 00:16:20 -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, keescook@chromium.org, dm-devel@redhat.com, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, linux-fsdevel@vger.kernel.org, colyli@suse.de, chengnt@lenovo.com, Huaisheng Ye Subject: [PATCH v3 2/6] s390, dcssblk: kaddr and pfn can be NULL to ->direct_access() Date: Mon, 30 Jul 2018 15:15:44 +0800 Message-Id: <20180730071548.9172-3-yehs2007@zoho.com> X-Mailer: git-send-email 2.17.0.windows.1 In-Reply-To: <20180730071548.9172-1-yehs2007@zoho.com> References: <20180730071548.9172-1-yehs2007@zoho.com> X-ZohoMailClient: External Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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 Reviewed-by: Ross Zwisler Acked-by: Martin Schwidefsky --- 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; }