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Re: CVS commit: src/sys/kern
Date: Tue, 15 Apr 2014 09:50:45 +0000
From: Juergen Hannken-Illjes <hannken%NetBSD.org@localhost>
Fix a deadlock where one thread exits, enters fstrans_lwp_dtor()
and wants fstrans_lock. This thread holds the proc_lock.
This sounds fishy. lwp_exit does not hold proc_lock while calling
lwp_finispecific, so there are no invariants covered by proc_lock that
the lwp_specific destructors can rely on. I'm inclined to say that it
is a bug for exit1 to hold proc_lock when it calls lwp_finispecific
(and proc_finispecific). Can we just release it before and re-acquire
it after calling lwp/proc_finispecific?
Another thread holds fstrans_lock and runs pserialize_perform().
As the first thread holds the proc_lock, timeouts are blocked and
the second thread blocks forever in kpause().
This also sounds fishy. How does T1's holding proc_lock cause T2 to
block forever in kpause? I think I'm missing something in this
analysis. kpause doesn't take proc_lock, does it?
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