From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from imap1.codethink.co.uk ([176.9.8.82]:58111 "EHLO imap1.codethink.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725921AbeIGE72 (ORCPT ); Fri, 7 Sep 2018 00:59:28 -0400 Message-ID: <1536279682.3024.95.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: Xiao Liang Cc: stable@vger.kernel.org, "David S. Miller" , Greg Kroah-Hartman , LKML Date: Fri, 07 Sep 2018 01:21:22 +0100 In-Reply-To: <20180804082706.393252081@linuxfoundation.org> References: <20180804082702.434482435@linuxfoundation.org> <20180804082706.393252081@linuxfoundation.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 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. Ben. -- Ben Hutchings, Software Developer   Codethink Ltd https://www.codethink.co.uk/ Dale House, 35 Dale Street Manchester, M1 2HF, United Kingdom