On Sat, Apr 23, 2022 at 06:07:23PM +0200, Lukas Wunner wrote: > On Thu, Apr 21, 2022 at 10:02:43AM +0200, Paolo Abeni wrote: > > On Sun, 2022-04-17 at 09:04 +0200, Lukas Wunner wrote: > > > --- a/net/core/link_watch.c > > > +++ b/net/core/link_watch.c > > > @@ -107,7 +107,8 @@ static void linkwatch_add_event(struct net_device *dev) > > > unsigned long flags; > > > > > > spin_lock_irqsave(&lweventlist_lock, flags); > > > - if (list_empty(&dev->link_watch_list)) { > > > + if (list_empty(&dev->link_watch_list) && > > > + dev->reg_state < NETREG_UNREGISTERED) { > > > list_add_tail(&dev->link_watch_list, &lweventlist); > > > dev_hold_track(dev, &dev->linkwatch_dev_tracker, GFP_ATOMIC); > > > > > > > What about testing dev->reg_state in linkwatch_fire_event() before > > setting the __LINK_STATE_LINKWATCH_PENDING bit, so that we don't leave > > the device in an unexpected state? About __LINK_STATE_LINKWATCH_PENDING being set even though the netdev is not on link_watch_list: After this patch (which removes one user of __LINK_STATE_LINKWATCH_PENDING) the only purpose of the flag is a small speed-up of linkwatch_fire_event(): If the netdev is already on link_watch_list, the function skips acquiring lweventlist_lock. I don't think this is a hotpath, so the small speed-up is probably not worth it and the flag could be removed completely in a follow-up patch. There is a single other (somewhat oddball) user of the flag in bond_should_notify_peers() in drivers/net/bonding/bond_main.c. It would be possible to replace it with "!list_empty(&dev->link_watch_list)". I don't think acquiring lweventlist_lock is necessary for that because test_bit() is unordered (per Documentation/atomic_bitops.txt) and the check is racy anyway. Thanks, Lukas