On Fri, Dec 14, 2018 at 02:53:00AM +0000, Govindarajulu Varadarajan (gvaradar) wrote: > On Tue, 2018-12-11 at 23:06 +0000, Jason Gunthorpe wrote: > > On Tue, Dec 11, 2018 at 02:15:41PM -0800, Parvi Kaustubhi wrote: > > > From: Govindarajulu Varadarajan <gvaradar@xxxxxxxxx> > > > > > > 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 locking: &usnic_ib_ibdev_list_lock -> usdev_lock -> rtnl_lock > > > > > > rtnl_lock() > > > > usnic_ib_netdevice_event() > > > | mutex_lock(&usnic_ib_ibdev_list_lock); > > > > > > Order of locking: rtnl_lock -> &usnic_ib_ibdev_list_lock > > > > > > The solution is to not handle usnic_ib_netdevice_event() with the rtnl > > > lock held. > > > This commit creates a single threaded workqueue to defer the handling of > > > netdev/inet events. > > > > > > Signed-off-by: Govindarajulu Varadarajan <gvaradar@xxxxxxxxx> > > > Signed-off-by: Parvi Kaustubhi <pkaustub@xxxxxxxxx> > > > drivers/infiniband/hw/usnic/usnic_ib.h | 6 +++ > > > drivers/infiniband/hw/usnic/usnic_ib_main.c | 60 ++++++++++++++++++++++++--- > > > > I'm really getting sick of seeing this same code pattern in the > > ethernet connecting drivers.. I think this is the 3rd time now I've > > seen a fix for this same rtnl locking bug in a driver. > > Is the issue here using a workqueue to handle notify? The issue is all the code duplication.. Jason
