From c269a24ce057abfc31130960e96ab197ef6ab196 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Wed, 6 Jan 2021 10:40:06 -0800 Subject: net: make free_netdev() more lenient with unregistering devices There are two flavors of handling netdev registration: - ones called without holding rtnl_lock: register_netdev() and unregister_netdev(); and - those called with rtnl_lock held: register_netdevice() and unregister_netdevice(). While the semantics of the former are pretty clear, the same can't be said about the latter. The netdev_todo mechanism is utilized to perform some of the device unregistering tasks and it hooks into rtnl_unlock() so the locked variants can't actually finish the work. In general free_netdev() does not mix well with locked calls. Most drivers operating under rtnl_lock set dev->needs_free_netdev to true and expect core to make the free_netdev() call some time later. The part where this becomes most problematic is error paths. There is no way to unwind the state cleanly after a call to register_netdevice(), since unreg can't be performed fully without dropping locks. Make free_netdev() more lenient, and defer the freeing if device is being unregistered. This allows error paths to simply call free_netdev() both after register_netdevice() failed, and after a call to unregister_netdevice() but before dropping rtnl_lock. Simplify the error paths which are currently doing gymnastics around free_netdev() handling. Signed-off-by: Jakub Kicinski --- net/8021q/vlan.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'net/8021q') diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c index 15bbfaf943fd..8b644113715e 100644 --- a/net/8021q/vlan.c +++ b/net/8021q/vlan.c @@ -284,9 +284,7 @@ static int register_vlan_device(struct net_device *real_dev, u16 vlan_id) return 0; out_free_newdev: - if (new_dev->reg_state == NETREG_UNINITIALIZED || - new_dev->reg_state == NETREG_UNREGISTERED) - free_netdev(new_dev); + free_netdev(new_dev); return err; } -- cgit v1.2.3