On 5/14/21 1:07 AM, Maximilian Luz wrote:

Following commit a05829a7222e ("cfg80211: avoid holding the RTNL when
calling the driver"), the mwifiex_pcie module fails to unload. This also
prevents the device from rebooting / shutting down.

Attempting to unload the module produces the log pasted below. Upon
further investigation, this looks like a deadlock inside
_cfg80211_unregister_wdev():

- According to [1], this function expects the rdev->wiphy.mtx to be
   held.
- Down the line, this function (through some indirections, see third
   trace in log below) calls call_netdevice_notifiers(NETDEV_GOING_DOWN,
   ...) [2].
- One of the registered notifiers seems to be
   cfg80211_netdev_notifier_call(), which attempts to lock
   rdev->wiphy.mtx again [3], completing the deadlock.

Looks like the underlying issue also leads to

   https://lore.kernel.org/linux-wireless/ab4d00ce52f32bd8e45ad0448a44737e@bewaar.me/ (local)

Regards,
Max