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=-5.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 B7768C48BDF for ; Fri, 18 Jun 2021 13:43:01 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 665BA60C41 for ; Fri, 18 Jun 2021 13:43:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 665BA60C41 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.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=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc: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=xIXgYYgVdwQ6z+j/kNNmE/Snh2/D6His9ndjbL4MKB4=; b=ObLMhFCDWYiCca L5iOkjO5g/yGP4ay0zeUE/Mn/4lta7coiq08QIpCnoHmEFIvafvX8V2KS4XUCBubSDAjA7codARMT VkVISM+4P7Id5z1U95M2pyPWgbpa2e3PQ3PuYIewNyR4FhYBPlqmeuXzaZNUgh9CJ5AljoPRugtBK qoWQghMEOd2gKKjmLEiryDdR9oM5os3ClJGtwtxU9HvmSJG93dubYd3XZonRh4KjJxuziC+SE0cvi Y1s7FvPzPsys9v7/z3xsoy8A4HpSZQ+uOftuLsMeQjPkdD/io/ovbudx3AATo8JIfvGXfZ0lzH9LV OmSQ6iq+gju4EGls3YDw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1luElp-00EKnw-8b; Fri, 18 Jun 2021 13:42:53 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1luEll-00EKn5-CL for linux-nvme@lists.infradead.org; Fri, 18 Jun 2021 13:42:51 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id E6D9368D08; Fri, 18 Jun 2021 15:42:44 +0200 (CEST) Date: Fri, 18 Jun 2021 15:42:44 +0200 From: Christoph Hellwig To: Prabhakar Kushwaha Cc: linux-nvme@lists.infradead.org, sagi@grimberg.me, hch@lst.de, kbusch@kernel.org, axboe@fb.com, martin.belanger@dell.com, aelior@marvell.com, okulkarni@marvell.com, smalin@marvell.com, prabhakar.pkin@gmail.com, malin1024@gmail.com Subject: Re: [PATCH] nvme-tcp: Use __dev_get_by_name instead dev_get_by_name for OPT_HOST_IFACE Message-ID: <20210618134244.GA16005@lst.de> References: <20210618133956.10637-1-pkushwaha@marvell.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210618133956.10637-1-pkushwaha@marvell.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210618_064249_606697_68E61441 X-CRM114-Status: GOOD ( 13.35 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 Fri, Jun 18, 2021 at 04:39:56PM +0300, Prabhakar Kushwaha wrote: > dev_get_by_name() finds network device by name but it also increases > reference count. > Increasing the ref count, > If nvme-tcp queue is present and the network device driver is removed > before nvme_tcp, we will face the following continuous log: > "kernel:unregister_netdevice: waiting for to become > free. Usage count = 2" > And rmmod further halts. Similar case arises during reboot/shutdown > with nvme-tcp queue present and both never completes. > > As a fix we will use __dev_get_by_name() which find network device by > name without increasing any reference counter. And when you remove it without the refcount we'll now have a stale kernel pointer? _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme