I need a little help in fixing `exclusive sleep mutex urtwn0_com_lock` in CURRENT

[Aleksander Alekseev]

> So as I understand some code acquired a mutex and didn't release it.
> And naturally it has something to do with USB. Now how can I figure
> out what code acquired this lock? Best approach I can think of
> currently is to find all places where this lock is accessed and add a
> debug logging. But perhaps there is a better way?

By any chance is it possible to trace mtx_lock / mtx_unlock calls using
DTrace? I see number of probes in `dtrace -l` which look like
something I need. Unfortunately they are named like knlist_mtx_lock or
do_lock_umutex so I can't figure out whether these are probes I looking
for or not.

cc: freebsd-dtrace@

-- 
Best regards,
Aleksander Alekseev
http://eax.me/