Date: Tue, 2 Jul 2002 09:51:41 -0700 (PDT) From: Julian Elischer <julian@elischer.org> To: Daniel Eischen <eischen@pcnet1.pcnet.com> Cc: Jonathan Lemon <jlemon@flugsvamp.com>, iedowse@maths.tcd.ie, current@FreeBSD.ORG Subject: Re: KSE status report Message-ID: <Pine.BSF.4.21.0207020930290.95531-100000@InterJet.elischer.org> In-Reply-To: <Pine.GSO.4.10.10207021212570.15661-100000@pcnet1.pcnet.com>
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I just removed the extra debug line in queue.h
that set the "next" pointer to -1 then the element was removed.
Since I was told that the problem still occurs with an old queue.h
I don;t think that that will fix it but we might as well try it
again with this change.
On Tue, 2 Jul 2002, Daniel Eischen wrote:
> On Tue, 2 Jul 2002, Jonathan Lemon wrote:
> > In article <local.mail.freebsd-current/200207021106.aa15257@salmon.maths.tcd.ie> you write:
> > >In message <Pine.BSF.4.21.0207020054590.94626-100000@InterJet.elischer.org>, Ju
> > >lian Elischer writes:
> > >>The big problem at the moment is that something in the
> > >>source tree as a whole, and probably something that came in with KSE
> > >>is stopping us from successfully compiling a working libc_r.
> > >>(a bit ironic really).
> > >
> > >Is the new
> > >
> > > (elm)->field.tqe_next = (void *)-1;
> > >
> > >in TAILQ_REMOVE a likely candidate? That could easily tickle old
> > >bugs in other code. The libc_r code does use a lot of TAILQ macros.
> >
> > >From casual inspection of the sources, it appears this may be the case:
> >
> > uthread/pthread_private.h:
> > #define PTHREAD_WORKQ_REMOVE(thrd) do { \
> > TAILQ_REMOVE(&_workq,thrd,qe); \
> > (thrd)->flags &= ~PTHREAD_FLAGS_IN_WORKQ; \
> > } while (0)
> >
> > uthread/uthread_kern.c (in multiple locations):
> > TAILQ_FOREACH(pthread, &_workq, qe) {
> > ....
> > PTHREAD_WORKQ_REMOVE(pthread);
> > }
>
> This used to be safe as long as the element removed wasn't re-added to
> another queue using the same link. There are other places in libc_r
> where we do re-use the same link (remove from one list and add to
> another), but roll our own loop in that case:
>
> for (p = TAILQ_FIRST(&q); p != NULL; p = p_next) {
> p_next = TAILQ_NEXT(p, p_qe);
> ...
> TAILQ_REMOVE(&q, pthread, p_qe);
> ...
> }
>
> --
> Dan Eischen
>
>
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