cvs commit: src/lib/libpthread/thread thr_private.h thr_sig.c

[John Baldwin]

On Tuesday 02 November 2004 06:40 pm, Daniel Eischen wrote:
> On Wed, 3 Nov 2004, David Xu wrote:
> > John Baldwin wrote:
> > >On Monday 01 November 2004 06:04 pm, David Xu wrote:
> > >>Not every important,  I think I have another very important history
> > >>bug in hand,  did you get my "fix famous libpthread conditional
> > >>variable race condition" mail ? :-)
> > >
> > >Oooo, can I test it please?  We are still having problems with mono on
> > > HEAD here at work.  I tried merging the changes in uthread_cond.c 1.32
> > > to libpthread but that seemed to make it worse.  The problems seem to
> > > be that a signal handler is being run when the SYNCQ sflag is set (but
> > > the thread is not on a cv or a mutex queue), and the handler calls
> > > sem_post() which is supposed to be signal safe.  sem_post() tries to
> > > lock a mutex and then bombs with the assertion failure.
> >
> > You can try:
> > http://people.freebsd.org/~davidxu/kse/thr_cond.c.diff
> >
> > But it was not designed to fix the problem you have seen. :-)
>
> I think if _kse_critical_leave() were replaced by _kcb_critical_leave()
> at around line 676 in thr_kern.c, that should fix the problem, no?
> There's no reason to do a yield check after leaving the scheduler,
> and the check for signals and cancellation is done right after
> that point before returning.

Well, it moved it. :)  Now thr_sig_rundown() is called from thr_resume_check() 
from thr_sched_switch_unlocked(), but psf->valid is zero, so it still doesn't 
work.  What would happen if the signal came in before curthread->frame was 
set to &psf in thread_sched_switch_unlocked()?

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org