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Fri, 27 Jul 2018 18:40:27 +0000 Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserv0021.oracle.com (8.14.4/8.14.4) with ESMTP id w6RIeQSe003002 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 27 Jul 2018 18:40:26 GMT Received: from abhmp0005.oracle.com (abhmp0005.oracle.com [141.146.116.11]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id w6RIePli015405; Fri, 27 Jul 2018 18:40:26 GMT Received: from dhcp-burlington7-2nd-B-east-10-152-55-162.usdhcp.oraclecorp.com (/10.152.32.65) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 27 Jul 2018 11:40:25 -0700 Subject: Re: [PATCH] xen-netfront: wait xenbus state change when load module manually To: Xiao Liang , netdev@vger.kernel.org, xen-devel@lists.xenproject.org, davem@davemloft.net, jgross@suse.com Cc: linux-kernel@vger.kernel.org References: <20180727095608.25210-1-xiliang@redhat.com> From: Boris Ostrovsky Openpgp: preference=signencrypt Autocrypt: addr=boris.ostrovsky@oracle.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180727095608.25210-1-xiliang@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8967 signatures=668706 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1806210000 definitions=main-1807270188 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/27/2018 05:56 AM, Xiao Liang wrote: > 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. > > Current state: > [vm]# ethtool eth0 > Settings for eth0: > Link detected: yes > [vm]# modprobe -r xen_netfront > [vm]# modprobe xen_netfront > [vm]# ethtool eth0 > Settings for eth0: > Cannot get device settings: No such device > Cannot get wake-on-lan settings: No such device > Cannot get message level: No such device > Cannot get link status: No such device > No data available > > With the patch installed. > [vm]# ethtool eth0 > Settings for eth0: > Link detected: yes > [vm]# modprobe -r xen_netfront > [vm]# modprobe xen_netfront > [vm]# ethtool eth0 > Settings for eth0: > Link detected: yes > > Signed-off-by: Xiao Liang > --- > drivers/net/xen-netfront.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c > index a57daecf1d57..2d8812dd1534 100644 > --- a/drivers/net/xen-netfront.c > +++ b/drivers/net/xen-netfront.c > @@ -87,6 +87,7 @@ 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 { > @@ -1330,6 +1331,11 @@ static struct net_device *xennet_create_dev(struct xenbus_device *dev) > 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: Should we have a wake_up somewhere? And what about other states --- is, for example, XenbusStateClosing a valid reason to continue? -boris