| Message ID | 20200226174723.5492-1-ap420073@gmail.com |
|---|---|
| State | Superseded |
| Delegated to: | David Miller |
| Headers | show |
| Series | net: rmnet: fix several bugs | expand |
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c index 93642cdd3305..c8b1bfe127ac 100644 --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c @@ -230,7 +230,6 @@ static void rmnet_force_unassociate_device(struct net_device *dev) port = rmnet_get_port_rtnl(dev); - rcu_read_lock(); rmnet_unregister_bridge(dev, port); hash_for_each_safe(port->muxed_ep, bkt_ep, tmp_ep, ep, hlnode) { @@ -241,7 +240,6 @@ static void rmnet_force_unassociate_device(struct net_device *dev) kfree(ep); } - rcu_read_unlock(); unregister_netdevice_many(&list); rmnet_unregister_real_device(real_dev, port);
The notifier_call() of the slave interface removes rmnet interface with unregister_netdevice_queue(). But, before calling unregister_netdevice_queue(), it acquires rcu readlock. In the RCU critical section, sleeping isn't be allowed. But, unregister_netdevice_queue() internally calls synchronize_net(), which would sleep. So, suspicious RCU usage warning occurs. Test commands: ip link add dummy0 type dummy ip link add dummy1 type dummy ip link add rmnet0 link dummy0 type rmnet mux_id 1 ip link del dummy0 Splat looks like: [ 128.764922][ T979] WARNING: suspicious RCU usage [ 128.766356][ T979] 5.5.0+ #416 Not tainted [ 128.767667][ T979] ----------------------------- [ 128.769008][ T979] ./include/linux/rcupdate.h:273 Illegal context switch in RCU read-side critical section! [ 128.771375][ T979] [ 128.771375][ T979] other info that might help us debug this: [ 128.771375][ T979] [ 128.773998][ T979] [ 128.773998][ T979] rcu_scheduler_active = 2, debug_locks = 1 [ 128.775572][ T979] 2 locks held by ip/979: [ 128.776507][ T979] #0: ffffffff9ccf6230 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x457/0x890 [ 128.778241][ T979] #1: ffffffff9c9254c0 (rcu_read_lock){....}, at: rmnet_config_notify_cb+0xf0/0x590 [rmnet] [ 128.779704][ T979] [ 128.779704][ T979] stack backtrace: [ 128.780699][ T979] CPU: 0 PID: 979 Comm: ip Not tainted 5.5.0+ #416 [ 128.781763][ T979] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 [ 128.783433][ T979] Call Trace: [ 128.783919][ T979] dump_stack+0x96/0xdb [ 128.784535][ T979] ___might_sleep+0x345/0x440 [ 128.785216][ T979] synchronize_net+0x18/0x30 [ 128.785868][ T979] netdev_rx_handler_unregister+0x40/0xb0 [ 128.786536][ T979] rmnet_unregister_real_device+0x42/0xb0 [rmnet] [ 128.787219][ T979] rmnet_config_notify_cb+0x1f7/0x590 [rmnet] [ 128.787859][ T979] ? rmnet_unregister_bridge.isra.6+0xf0/0xf0 [rmnet] [ 128.788668][ T979] ? rmnet_unregister_bridge.isra.6+0xf0/0xf0 [rmnet] [ 128.789347][ T979] ? __module_text_address+0x13/0x140 [ 128.789853][ T979] notifier_call_chain+0x90/0x160 [ 128.790353][ T979] rollback_registered_many+0x660/0xcf0 [ 128.790877][ T979] ? netif_set_real_num_tx_queues+0x780/0x780 [ 128.791452][ T979] ? __lock_acquire+0xdfe/0x3de0 [ 128.791926][ T979] ? memset+0x1f/0x40 [ 128.792309][ T979] ? __nla_validate_parse+0x98/0x1ab0 [ 128.793033][ T979] unregister_netdevice_many.part.134+0x13/0x1b0 [ 128.794060][ T979] rtnl_delete_link+0xbc/0x100 [ ... ] Fixes: ceed73a2cf4a ("drivers: net: ethernet: qualcomm: rmnet: Initial implementation") Signed-off-by: Taehee Yoo <ap420073@gmail.com> --- drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c | 2 -- 1 file changed, 2 deletions(-)