sigwait() brokeness (was Re: Threads regression tests)

[David Xu]

----- Original Message ----- 
From: "Daniel Eischen" <eischen at vigrid.com>
To: "David Schultz" <das at freebsd.org>
Cc: "Craig Rodrigues" <rodrigc at crodrigues.org>; "David Xu" <davidxu at freebsd.org>; <freebsd-threads at freebsd.org>
Sent: Thursday, July 17, 2003 3:15 AM
Subject: sigwait() brokeness (was Re: Threads regression tests)


> On Tue, 15 Jul 2003, David Schultz wrote:
> 
> > On Wed, Jul 16, 2003, David Xu wrote:
> > > Can you test my libkse patch ?
> > > http://people.freebsd.org/~davidxu/libpthread_bound.diffs
> > > If you can test the patch to make sure I don't break signal
> > > code, then I will commit this patch. 
> > 
> > Is there interest in incrementally building a threads-related
> > regression test suite in src/tools/regression?  This would mean
> > less breakage for people who are trying to use KSE/libthr, and an
> > easy way for threads developers to be somewhat confident that
> > their changes are correct.  For example, two weeks ago I was
> > tearing my hair out over a sigwait() problem that caused the
> > following program to deadlock.  Since I already bothered to
> > isolate the bug, why not do the last 1% of the work and check in a
> > test so that it never comes back?  Thoughts?
> 
> Yes, sigwait() appears to be broken in the kernel.
> If the process is sigwait()ing on a signal set, and
> one of those signals is pending or occurs, the
> signal handler should not be invoked, especially
> if the signal is masked.
> 
> The waitset is independent of the thread's signal
> mask.  I think struct thread needs to grow a td_waitset
> member.  If a signal arrives (or is already pending)
> and it is present in the waitset, then the thread
> should be woken up with the signal removed from the
> pending set and no signal handler installed.
> 

I am working on it now. 

> -- 
> Dan Eischen
> 
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