Hi,
With the help of a static bug finder (EBA -
https://github.com/models-team/eba) I have found a potential deadlock
in drivers/net/wireless/st/cw1200/
sta.c. This happens due to a recursive mutex_lock on `priv->conf_mutex'.
If this is indeed a bug, I will be happy to help with a patch.
A quick (not elegant) fix could be to unlock before the call to
`cw1200_do_unjoin' in line 1174, and lock again afterwards. It seems
that `cw1200_join_complete' is always called with `priv->conf_mutex'
held. Another option could be to add a Boolean parameter to
`cw1200_do_unjoin' to choose whether this function should take the
lock itself. Yet another option would be to have a
`__cw1200_do_unjoin' that does not lock, and make `cw1200_do_unjoin' a
wrapper over this that adds the locking; `cw1200_join_complete' would
call `__cw1200_do_unjoin' instead.
Someone who is actually familiar with this code may have a better
proposal though.
The trace is as follows:
1. Function `cw1200_join_complete_work' takes the first lock in line 1189:
// see
https://github.com/torvalds/linux/blob/v4.9-rc5/drivers/net/wireless/st/cw1200/sta.c#L1189
mutex_lock(& priv->conf_mutex);
2. and subsequently calls `cw1200_join_complete';
3. which calls `cw1200_do_unjoin' in line 1174;
4. and this latter function takes the lock for the second time in line 1387:
// see
https://github.com/torvalds/linux/blob/v4.9-rc5/drivers/net/wireless/st/cw1200/sta.c#L1387
mutex_lock(& priv->conf_mutex);
Hope it helps!
--
iago
