From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: 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 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> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 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