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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 9473FC6778D for ; Tue, 11 Sep 2018 18:16:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4BE042086E for ; Tue, 11 Sep 2018 18:16:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4BE042086E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=codethink.co.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728136AbeIKXRH (ORCPT ); Tue, 11 Sep 2018 19:17:07 -0400 Received: from imap1.codethink.co.uk ([176.9.8.82]:50474 "EHLO imap1.codethink.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727332AbeIKXRG (ORCPT ); Tue, 11 Sep 2018 19:17:06 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126] helo=xylophone) by imap1.codethink.co.uk with esmtpsa (Exim 4.84_2 #1 (Debian)) id 1fznDA-0008HY-GA; Tue, 11 Sep 2018 19:16:28 +0100 Message-ID: <1536689787.3024.130.camel@codethink.co.uk> Subject: Re: [PATCH 4.4 105/124] xen-netfront: wait xenbus state change when load module manually From: Ben Hutchings To: Boris Ostrovsky , Xiao Liang Cc: stable@vger.kernel.org, "David S. Miller" , Greg Kroah-Hartman , LKML , Juergen Gross Date: Tue, 11 Sep 2018 19:16:27 +0100 In-Reply-To: References: <20180804082702.434482435@linuxfoundation.org> <20180804082706.393252081@linuxfoundation.org> <1536279682.3024.95.camel@codethink.co.uk> Organization: Codethink Ltd. Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6-1+deb9u1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2018-09-07 at 13:27 -0400, Boris Ostrovsky wrote: > On 09/06/2018 08:21 PM, Ben Hutchings wrote: > > On Sat, 2018-08-04 at 11:01 +0200, Greg Kroah-Hartman wrote: > > > 4.4-stable review patch.  If anyone has any objections, please let me know. > > > > > > ------------------ > > > > > > From: Xiao Liang > > > > > > [ Upstream commit 822fb18a82abaf4ee7058793d95d340f5dab7bfc ] > > > > > > When loading module manually, after call xenbus_switch_state to initializes > > > the state of the netfront device, the driver state did not change so fast > > > that may lead no dev created in latest kernel. This patch adds wait to make > > > sure xenbus knows the driver is not in closed/unknown state. > > > > [...] > > > --- a/drivers/net/xen-netfront.c > > > +++ b/drivers/net/xen-netfront.c > > > @@ -86,6 +86,7 @@ struct netfront_cb { > > >  /* IRQ name is queue name with "-tx" or "-rx" appended */ > > >  #define IRQ_NAME_SIZE (QUEUE_NAME_SIZE + 3) > > >   > > > +static DECLARE_WAIT_QUEUE_HEAD(module_load_q); > > >  static DECLARE_WAIT_QUEUE_HEAD(module_unload_q); > > >   > > >  struct netfront_stats { > > > @@ -1335,6 +1336,11 @@ static struct net_device *xennet_create_ > > >   netif_carrier_off(netdev); > > >   > > >   xenbus_switch_state(dev, XenbusStateInitialising); > > > + wait_event(module_load_q, > > > +    xenbus_read_driver_state(dev->otherend) != > > > +    XenbusStateClosed && > > > +    xenbus_read_driver_state(dev->otherend) != > > > +    XenbusStateUnknown); > > >   return netdev; > > >   > > >   exit: > > > > This won't work; it will hang.  Something (maybe netback_changed()?) > > needs to wake up tasks on the module_load_q. > > > https://lkml.org/lkml/2018/9/7/691 Thanks. Ben. -- Ben Hutchings, Software Developer   Codethink Ltd https://www.codethink.co.uk/ Dale House, 35 Dale Street Manchester, M1 2HF, United Kingdom