> -----Original Message----- > From: Vitaly Kuznetsov [mailto:vkuznets@xxxxxxxxxx] > Sent: Thursday, August 11, 2016 6:59 AM > To: netdev@xxxxxxxxxxxxxxx > Cc: devel@xxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Haiyang > Zhang <haiyangz@xxxxxxxxxxxxx>; KY Srinivasan <kys@xxxxxxxxxxxxx> > Subject: [PATCH net 4/4] hv_netvsc: avoid deadlocks between rtnl lock and > netvsc_inject_disable() > > Here is a deadlock scenario: > - netvsc_vf_up() schedules netvsc_notify_peers() work and quits. > - netvsc_vf_down() runs before netvsc_notify_peers() gets executed. As it > is being executed from netdev notifier chain we hold rtnl lock when we > get here. > - we enter netvsc_inject_disable() and loop and wait till > netvsc_notify_peers() drops vf_use_cnt. > - netvsc_notify_peers() starts on some other CPU but netdev_notify_peers() > will hang on rtnl_lock(). > - deadlock! > > Similar deadlocks are possible between netvsc_vf_{up,down}() and > netvsc_unregister_vf() as it also waits till vf_use_cnt drops to zero. > Instead of introducing additional synchronization I suggest we drop > gwrk.dwrk completely and call NETDEV_NOTIFY_PEERS directly. As we're > acting under rtnl lock this is legitimate. > > Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> Acked-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx> _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
