Hi, This still looks like a deadlock bug to me, could someone take a look as well and confirm? I will help preparing a patch if needed. Thanks, -- iago On Fri, Nov 18, 2016 at 10:58 PM, Iago Abal <iago.abal@xxxxxxxxx> wrote: > 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
