On Fri, Feb 08, 2019 at 01:53:44PM -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 use ib_device_get_by_netdev() to lookup ib_dev while > handling netdev/ inet events. > > Signed-off-by: Parvi Kaustubhi <pkaustub@xxxxxxxxx> > Reviewed-by: Govindarajulu Varadarajan <gvaradar@xxxxxxxxx> > Reviewed-by: Tanmay Inamdar <tinamdar@xxxxxxxxx> > Changelog: > > v2->v3: > * Jason: drivers should not hold any locks while calling ib_unregister_device() > * Jason: use https://github.com/jgunthorpe/linux/commits/device_locking_cleanup > > v1->v2: > * Have notifier blocks in usnic_ib_dev instead of using workqueue to defer > event handling. > drivers/infiniband/hw/usnic/usnic_ib_main.c | 34 ++++++++++++++--------------- > 1 file changed, 16 insertions(+), 18 deletions(-) > > diff --git a/drivers/infiniband/hw/usnic/usnic_ib_main.c b/drivers/infiniband/hw/usnic/usnic_ib_main.c > index 9529a08..53d6c12 100644 > +++ b/drivers/infiniband/hw/usnic/usnic_ib_main.c > @@ -216,18 +216,17 @@ static int usnic_ib_netdevice_event(struct notifier_block *notifier, > unsigned long event, void *ptr) > { > struct usnic_ib_dev *us_ibdev; > + struct ib_device *ibdev; > > struct net_device *netdev = netdev_notifier_info_to_dev(ptr); > > - mutex_lock(&usnic_ib_ibdev_list_lock); > - list_for_each_entry(us_ibdev, &usnic_ib_ibdev_list, ib_dev_link) { > - if (us_ibdev->netdev == netdev) { > - usnic_ib_handle_usdev_event(us_ibdev, event); > - break; > - } > - } > - mutex_unlock(&usnic_ib_ibdev_list_lock); > - > + ibdev = ib_device_get_by_netdev(netdev, RDMA_DRIVER_USNIC); > + if (!ibdev) > + goto exit; > + else > + us_ibdev = container_of(ibdev, struct usnic_ib_dev, ib_dev); Just do if (!ibdev) return NOTIFY_DONE instead of all this wonky control flow. > + usnic_ib_handle_usdev_event(us_ibdev, event); All the ib_device_get_* calls need to be paired with an ib_device_put() Jason
