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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 37CE3C433DB for ; Thu, 28 Jan 2021 08:01:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E4C7264DD8 for ; Thu, 28 Jan 2021 08:01:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232257AbhA1IBe (ORCPT ); Thu, 28 Jan 2021 03:01:34 -0500 Received: from mx2.suse.de ([195.135.220.15]:53004 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232201AbhA1H7y (ORCPT ); Thu, 28 Jan 2021 02:59:54 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id ED9D5AC45; Thu, 28 Jan 2021 07:58:37 +0000 (UTC) Date: Thu, 28 Jan 2021 08:58:37 +0100 From: Daniel Wagner To: Chao Leng Cc: linux-nvme@lists.infradead.org, Sagi Grimberg , linux-kernel@vger.kernel.org, Jens Axboe , Hannes Reinecke , Keith Busch , Christoph Hellwig Subject: Re: [PATCH v2] nvme-multipath: Early exit if no path is available Message-ID: <20210128075837.u5u56t23fq5gu6ou@beryllium.lan> References: <20210127103033.15318-1-dwagner@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 28, 2021 at 09:31:30AM +0800, Chao Leng wrote: > > --- a/drivers/nvme/host/multipath.c > > +++ b/drivers/nvme/host/multipath.c > > @@ -221,7 +221,7 @@ static struct nvme_ns *nvme_round_robin_path(struct nvme_ns_head *head, > > } > > for (ns = nvme_next_ns(head, old); > > - ns != old; > > + ns && ns != old; > nvme_round_robin_path just be called when !"old". > nvme_next_ns should not return NULL when !"old". > It seems unnecessary to add checking "ns". The problem is when we enter nvme_round_robin_path() and there is no path available. In this case the initialization ns = nvme_next_ns(head, old) could return a NULL pointer. 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=-9.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 85D39C433E0 for ; Thu, 28 Jan 2021 07:58:46 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 0313064DD8 for ; Thu, 28 Jan 2021 07:58:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0313064DD8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=VpZSufcz1w18pcVW9TMy0945OxYu6KSEVUJ6pWczYvQ=; b=zhbgEn39J7J8skRRcy45L3sZX BSn0deJV8d+r7U2pUq1ormU68WKjoma0ykb5Wm6+gc5CGrCc5cEPu/+05PMwxX8xfuZkVFHFMO7kh MnhbTV5QWyMT+SmAHrd7tHdgHZvct4p5md0LUhHyyA5ddJASRsIwhZtS9m48Z+W4z3Z/UluQSe6De Eyf+8uo+QXBngyKVanls6Eharwi9WGe1GFZNmvDYUTpxhZ6pdHOEsz3+iflN/3+y5m7AMcfkeOWS/ wIFq2HTv6DDaGLcB1e15n6X/lcZSrDeM+jukExnCQrwUjB97ZJndVHPuXd0Qq5C6+SeLTxHRowafm DHMmJXeVQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l52CR-0005Wl-0i; Thu, 28 Jan 2021 07:58:43 +0000 Received: from mx2.suse.de ([195.135.220.15]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l52CM-0005VK-W4 for linux-nvme@lists.infradead.org; Thu, 28 Jan 2021 07:58:40 +0000 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id ED9D5AC45; Thu, 28 Jan 2021 07:58:37 +0000 (UTC) Date: Thu, 28 Jan 2021 08:58:37 +0100 From: Daniel Wagner To: Chao Leng Subject: Re: [PATCH v2] nvme-multipath: Early exit if no path is available Message-ID: <20210128075837.u5u56t23fq5gu6ou@beryllium.lan> References: <20210127103033.15318-1-dwagner@suse.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210128_025839_178850_11DE494C X-CRM114-Status: GOOD ( 15.12 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Sagi Grimberg , linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Jens Axboe , Hannes Reinecke , Keith Busch , Christoph Hellwig Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Thu, Jan 28, 2021 at 09:31:30AM +0800, Chao Leng wrote: > > --- a/drivers/nvme/host/multipath.c > > +++ b/drivers/nvme/host/multipath.c > > @@ -221,7 +221,7 @@ static struct nvme_ns *nvme_round_robin_path(struct nvme_ns_head *head, > > } > > for (ns = nvme_next_ns(head, old); > > - ns != old; > > + ns && ns != old; > nvme_round_robin_path just be called when !"old". > nvme_next_ns should not return NULL when !"old". > It seems unnecessary to add checking "ns". The problem is when we enter nvme_round_robin_path() and there is no path available. In this case the initialization ns = nvme_next_ns(head, old) could return a NULL pointer. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme