> -----Original Message----- > From: Jason Wang [mailto:jasowang@xxxxxxxxxx] > Sent: Wednesday, March 5, 2014 12:57 AM > To: Haiyang Zhang; davem@xxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx > Cc: KY Srinivasan; olaf@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; driverdev- > devel@xxxxxxxxxxxxxxxxxxxxxx > Subject: Re: [PATCH net-next] hyperv: Move state setting for link query > > On 03/05/2014 12:57 AM, Haiyang Zhang wrote: > > > >> -----Original Message----- > >> From: Jason Wang [mailto:jasowang@xxxxxxxxxx] > >> Sent: Monday, March 3, 2014 10:10 PM > >> To: Haiyang Zhang; davem@xxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx > >> Cc: KY Srinivasan; olaf@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > >> driverdev- devel@xxxxxxxxxxxxxxxxxxxxxx > >> 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 > > > > I see. Then if the link status is changing during mtu changing in guest. > Looks like we may miss a link status updating? When changing mtu, rndis_filter_device_add() is called, and host will send a link status call back immediately after connect-to-netvsp, no matter the link is changing or not. This will schedule a work to update the status. Thanks, - Haiyang _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
