Date: Wed, 3 Nov 2004 14:31:16 -0500 From: John Baldwin <jhb@FreeBSD.org> To: Daniel Eischen <deischen@FreeBSD.org> Cc: Julian Elischer <julian@elischer.org> Subject: Re: cvs commit: src/lib/libpthread/thread thr_private.h thr_sig.c Message-ID: <200411031431.16218.jhb@FreeBSD.org> In-Reply-To: <Pine.GSO.4.43.0411021838240.5097-100000@sea.ntplx.net> References: <Pine.GSO.4.43.0411021838240.5097-100000@sea.ntplx.net>
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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@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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