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
