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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA0D7C7EE2E for ; Wed, 24 May 2023 01:35:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239014AbjEXBfN (ORCPT ); Tue, 23 May 2023 21:35:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37642 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232881AbjEXBfN (ORCPT ); Tue, 23 May 2023 21:35:13 -0400 X-Greylist: delayed 58450 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Tue, 23 May 2023 18:35:11 PDT Received: from out-24.mta1.migadu.com (out-24.mta1.migadu.com [95.215.58.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 783E4130 for ; Tue, 23 May 2023 18:35:11 -0700 (PDT) Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1684892109; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=i761iZFwKwqHtc07peEjJ/qvFbYoc54lHLPk4d5Gw9g=; b=fpTFPcxcbP+q7k96H5fTIPKd6BzYAoI2feC/5DeCzdADTH+grWRNwR5Y0sB2/u22k+h0Tt uwAtsEvBwvkvJscWmJY6lNtjC4yhcAMByV7d1Sm3POUXlFnroVcOFlyyN/xvqTNUnb6Ahx JDGWpI7Lolko19FC/VhFHBQSseG/osM= Date: Wed, 24 May 2023 09:35:05 +0800 MIME-Version: 1.0 Subject: Re: [PATCH 04/10] block/rnbd-srv: no need to check sess_dev To: Jinpu Wang Cc: haris.iqbal@ionos.com, axboe@kernel.dk, linux-block@vger.kernel.org References: <20230523075331.32250-1-guoqing.jiang@linux.dev> <20230523075331.32250-5-guoqing.jiang@linux.dev> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Guoqing Jiang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 5/23/23 17:27, Jinpu Wang wrote: > On Tue, May 23, 2023 at 9:53 AM Guoqing Jiang wrote: >> Check ret is enough since if sess_dev is NULL which also >> implies ret should be 0. >> >> Signed-off-by: Guoqing Jiang >> --- >> drivers/block/rnbd/rnbd-srv.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/block/rnbd/rnbd-srv.c b/drivers/block/rnbd/rnbd-srv.c >> index e9ef6bd4b50c..c4122e65b36a 100644 >> --- a/drivers/block/rnbd/rnbd-srv.c >> +++ b/drivers/block/rnbd/rnbd-srv.c >> @@ -96,7 +96,7 @@ rnbd_get_sess_dev(int dev_id, struct rnbd_srv_session *srv_sess) >> ret = kref_get_unless_zero(&sess_dev->kref); >> rcu_read_unlock(); >> >> - if (!sess_dev || !ret) >> + if (!ret) >> return ERR_PTR(-ENXIO); >> >> return sess_dev; >> -- >> 2.35.3 > This looks wrong, if you drop the check for !sess_dev, you have to > check it later with IS_ERR_OR_NULL when call rnbd_get_sess_dev How can it return NULL? Pls correct me if I am wrong. 1. If sess_dev is NULL then ret is 0, so it just returns ERR_PTR(-ENXIO). 2. If sess_dev is not NULL, we still rely on the checking of ret. But I can drop it as well if you think it is obscure. Thanks, Guoqing