This time, only RTNL locking reduction fallout.
 - cfg80211_dev_rename() requires RTNL
 - cfg80211_change_iface() and cfg80211_set_encryption()
   require wiphy mutex (was missing in wireless extensions)
 - cfg80211_destroy_ifaces() requires wiphy mutex
 - netdev registration can fail due to notifiers, and then
   notifiers are "unrolled", need to handle this properly
cfg80211: fix netdev registration deadlock

If register_netdevice() fails after having called cfg80211's
netdev notifier (cfg80211_netdev_notifier_call) it will call
the notifier again with UNREGISTER. This would then lock the
wiphy mutex because we're marked as registered, which causes
a deadlock.

Fix this by separately keeping track of whether or not we're
in the middle of registering to also skip the notifier call
on this unregister.

Fixes: a05829a7222e ("cfg80211: avoid holding the RTNL when calling the driver")
Signed-off-by: Johannes Berg <>
2 files changed