On Tue, Feb 05, 2019 at 05:24:37PM -0800, Parvi Kaustubhi wrote: > There is a dead lock in usnic ib_register and netdev_notify > path. > > usnic_ib_discover_pf() > | mutex_lock(&usnic_ib_ibdev_list_lock); > | usnic_ib_device_add(); > | ib_register_device() > | usnic_ib_query_port() > | mutex_lock(&us_ibdev->usdev_lock); > | ib_get_eth_speed() > | rtnl_lock() > order of lock: &usnic_ib_ibdev_list_lock -> usdev_lock -> rtnl_lock > > rtnl_lock() > | usnic_ib_netdevice_event() > | mutex_lock(&usnic_ib_ibdev_list_lock); > > order of lock: rtnl_lock -> &usnic_ib_ibdev_list_lock > > Solution is to add notifier blocks (netdev_nb and inet_nb) for each pf > and use container_of to lookup usnic_ib_dev while handling netdev/ inet > events. This eliminates the need to acquire usnic_ib_ibdev_list_lock to > obtain the corresponding usnic_ib_dev pointer. What you should do is use this series: https://github.com/jgunthorpe/linux/commits/device_locking_cleanup And make a patch to convert usnic to use ib_device_set_netdev() and ib_device_get_by_netdev() and try to eliminate as many uses of the usnic_ib_ibdev_list as you can. Also, drivers should not hold any locks while calling ib_unregister_device() Jason
