> -----Original Message----- > From: Jason Wang [mailto:jasow...@redhat.com] > Sent: Monday, March 3, 2014 10:10 PM > To: Haiyang Zhang; da...@davemloft.net; net...@vger.kernel.org > Cc: KY Srinivasan; o...@aepfle.de; linux-kernel@vger.kernel.org; driverdev- > de...@linuxdriverproject.org > Subject: Re: [PATCH net-next] hyperv: Move state setting for link query > > On 03/04/2014 07:54 AM, Haiyang Zhang wrote: > > It moves the state setting for query into rndis_filter_receive_response(). > > All callbacks including query-complete and status-callback are > > synchronized by channel->inbound_lock. This prevents pentential race > between them. > > This still looks racy to me. The problem is workqueue is not synchronized with > those here. > > Consider the following case in netvsc_link_change(): > > if (rdev->link_state) { > ... receive interrupt ... > rndis_filter_receice_response() which changes rdev->link_state > ... > netif_carrier_off() > } > > And also it need to schedule a work otherwise the link status is out of sync.
The rndis_filter_query_device_link_status() makes the query and wait for the complete message, including set state, before returning. The rndis_filter_query_device_link_status() is called from rndis_filter_device_add(), which is called from either netvsc_change_mtu() or netvsc_probe(). The change_mtu() and netvsc_link_change() are synchronized by rtnl_lock(). In netvsc_probe(), the status query & complete happens before register_netdev(), and the netvsc_linkstatus_callback() schedules the work only after netdevice is registered. So, there are no race in either case. The carrier_on/off work will be scheduled when netvsc_open() is called. Then, the status will be updated based on the latest link_state. Thanks, - Haiyang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
