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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 0B7C0C2BBCF for ; Fri, 18 Dec 2020 06:10:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CBD8623A1E for ; Fri, 18 Dec 2020 06:10:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732629AbgLRGKC (ORCPT ); Fri, 18 Dec 2020 01:10:02 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:9226 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725298AbgLRGKB (ORCPT ); Fri, 18 Dec 2020 01:10:01 -0500 Received: from DGGEMS412-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4Cxz236Fl7zksDZ; Fri, 18 Dec 2020 14:08:27 +0800 (CST) Received: from [127.0.0.1] (10.174.177.9) by DGGEMS412-HUB.china.huawei.com (10.3.19.212) with Microsoft SMTP Server id 14.3.498.0; Fri, 18 Dec 2020 14:09:16 +0800 Subject: Re: [PATCH 1/1] device-dax: avoid an unnecessary check in alloc_dev_dax_range() To: Dan Williams , Vishal Verma , Dave Jiang , linux-nvdimm , linux-kernel References: <20201120092251.2197-1-thunder.leizhen@huawei.com> From: "Leizhen (ThunderTown)" Message-ID: <55970773-35ff-1afb-940b-8342b09aea9a@huawei.com> Date: Fri, 18 Dec 2020 14:09:15 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20201120092251.2197-1-thunder.leizhen@huawei.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.9] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/11/20 17:22, Zhen Lei wrote: > Swap the calling sequence of krealloc() and __request_region(), call the > latter first. In this way, the value of dev_dax->nr_range does not need to > be considered when __request_region() failed. > > Signed-off-by: Zhen Lei > --- > drivers/dax/bus.c | 29 ++++++++++++----------------- > 1 file changed, 12 insertions(+), 17 deletions(-) > > diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c > index 27513d311242..1efae11d947a 100644 > --- a/drivers/dax/bus.c > +++ b/drivers/dax/bus.c > @@ -763,23 +763,15 @@ static int alloc_dev_dax_range(struct dev_dax *dev_dax, u64 start, > return 0; > } > > - ranges = krealloc(dev_dax->ranges, sizeof(*ranges) > - * (dev_dax->nr_range + 1), GFP_KERNEL); > - if (!ranges) > - return -ENOMEM; > - > alloc = __request_region(res, start, size, dev_name(dev), 0); > - if (!alloc) { > - /* > - * If this was an empty set of ranges nothing else > - * will release @ranges, so do it now. > - */ > - if (!dev_dax->nr_range) { > - kfree(ranges); > - ranges = NULL; > - } > - dev_dax->ranges = ranges; > + if (!alloc) > return -ENOMEM; > + > + ranges = krealloc(dev_dax->ranges, sizeof(*ranges) > + * (dev_dax->nr_range + 1), GFP_KERNEL); > + if (!ranges) { > + rc = -ENOMEM; > + goto err; Hi, Dan Williams: In fact, after adding the new helper dev_dax_trim_range(), we can directly call __release_region() and return error code at here. Replace goto. > } > > for (i = 0; i < dev_dax->nr_range; i++) > @@ -808,11 +800,14 @@ static int alloc_dev_dax_range(struct dev_dax *dev_dax, u64 start, > dev_dbg(dev, "delete range[%d]: %pa:%pa\n", dev_dax->nr_range - 1, > &alloc->start, &alloc->end); > dev_dax->nr_range--; > - __release_region(res, alloc->start, resource_size(alloc)); > - return rc; > + goto err; > } > > return 0; > + > +err: > + __release_region(res, alloc->start, resource_size(alloc)); > + return rc; > } > > static int adjust_dev_dax_range(struct dev_dax *dev_dax, struct resource *res, resource_size_t size) >