From patchwork Wed Aug 19 02:05:02 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Leizhen (ThunderTown)" X-Patchwork-Id: 11722355 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5D54C138C for ; Wed, 19 Aug 2020 02:05:50 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 45CE02075E for ; Wed, 19 Aug 2020 02:05:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 45CE02075E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 126DA134CA7F2; Tue, 18 Aug 2020 19:05:50 -0700 (PDT) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=45.249.212.32; helo=huawei.com; envelope-from=thunder.leizhen@huawei.com; receiver= Received: from huawei.com (szxga06-in.huawei.com [45.249.212.32]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 9AAE313093FC5 for ; Tue, 18 Aug 2020 19:05:47 -0700 (PDT) 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 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 X-Originating-IP: [10.174.177.253] X-CFilter-Loop: Reflected Message-ID-Hash: YQT4QE6TDC6PEJOUYFGQ76L6524OH4OM X-Message-ID-Hash: YQT4QE6TDC6PEJOUYFGQ76L6524OH4OM X-MailFrom: thunder.leizhen@huawei.com X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: Zhen Lei X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: 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; }