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=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 8E9DBC433E5 for ; Wed, 19 Aug 2020 02:05:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 79AAD20829 for ; Wed, 19 Aug 2020 02:05:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727073AbgHSCFv (ORCPT ); Tue, 18 Aug 2020 22:05:51 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:53804 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726772AbgHSCFq (ORCPT ); Tue, 18 Aug 2020 22:05:46 -0400 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id A1E71CAB0D9349564C39; Wed, 19 Aug 2020 10:05:44 +0800 (CST) Received: from DESKTOP-C3MD9UG.china.huawei.com (10.174.177.253) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.487.0; Wed, 19 Aug 2020 10:05:34 +0800 From: Zhen Lei To: Oliver O'Halloran , Dan Williams , Vishal Verma , "Dave Jiang" , Ira Weiny , Markus Elfring , linux-nvdimm , linux-kernel CC: Zhen Lei Subject: [PATCH v2 3/4] libnvdimm/bus: simplify walk_to_nvdimm_bus() Date: Wed, 19 Aug 2020 10:05:02 +0800 Message-ID: <20200819020503.3079-4-thunder.leizhen@huawei.com> X-Mailer: git-send-email 2.26.0.windows.1 In-Reply-To: <20200819020503.3079-1-thunder.leizhen@huawei.com> References: <20200819020503.3079-1-thunder.leizhen@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.174.177.253] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I first want to move dev_WARN_ONCE() after "if (dev)" branch, but further I find the "if (dev)" can only be true when is_nvdimm_bus(dev) successed. No functional change. In fact, the compiler can optimize it correctly. I run "size drivers/nvdimm/bus.o" and find nothing has changed. So it's just source code level optimization, make us can read it faster. Signed-off-by: Zhen Lei --- drivers/nvdimm/bus.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c index 955265656b96c73..1d89114cb6ab93e 100644 --- a/drivers/nvdimm/bus.c +++ b/drivers/nvdimm/bus.c @@ -316,10 +316,9 @@ struct nvdimm_bus *walk_to_nvdimm_bus(struct device *nd_dev) for (dev = nd_dev; dev; dev = dev->parent) if (is_nvdimm_bus(dev)) - break; - dev_WARN_ONCE(nd_dev, !dev, "invalid dev, not on nd bus\n"); - if (dev) - return to_nvdimm_bus(dev); + return to_nvdimm_bus(dev); + + dev_WARN_ONCE(nd_dev, 1, "invalid dev, not on nd bus\n"); return NULL; } -- 1.8.3