Date: Thu, 23 Sep 2004 16:19:34 -0700 From: Nate Lawson <nate@root.org> To: Brian Fundakowski Feldman <green@FreeBSD.org> Cc: Joerg Wunsch <joerg@FreeBSD.org> Subject: Re: cvs commit: src/sys/dev/fdc fdc.c fdcvar.h Message-ID: <41535A06.7090809@root.org> In-Reply-To: <20040923224739.GE959@green.homeunix.org> References: <200409232112.i8NLCLgQ065917@repoman.freebsd.org> <200409231748.19685.jhb@FreeBSD.org> <20040923224739.GE959@green.homeunix.org>
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Brian Fundakowski Feldman wrote:
> On Thu, Sep 23, 2004 at 05:48:19PM -0400, John Baldwin wrote:
>
>>On Thursday 23 September 2004 05:12 pm, Joerg Wunsch wrote:
>>
>>>joerg 2004-09-23 21:12:21 UTC
>>>
>>> FreeBSD src repository
>>>
>>> Modified files:
>>> sys/dev/fdc fdc.c fdcvar.h
>>> Log:
>>> Implement terminating the worker thread when the driver is about to
>>> be deregistered.
>>>
>>> Not yet tested, since by now, GEOM doesn't want us to deregister. PHK
>>> wants to fix that RSN.
>>
>>Note that relying on a wakeup from your own code is not safe if you expect fdc
>>to be a module since you could wakeup the thread doing the kldunload (and
>>thus detach) and then be interrupted for an interrupt and it could unmap the
>>memory backing that function before you get a chance to run again resulting
>>in a panic. There is a special wakeup on the proc pointer in exit1() for
>>kthreads to handle this case. I should likely move that into kthread_exit()
>>however (which wouldn't be a functional change as far as you are concerned).
>
>
> For example, in pff(4), ignoring the unrelated lines of code:
>
> static void
> pff_per_device_kthread(void *argp)
> {
> mtx_lock(&sc->sc_lock);
> while (!sck->sck_exit) {
> if (!sck->sck_update && !sck->sck_reset &&
> STAILQ_EMPTY(&sck->sck_traps))
> cv_wait(&sck->sck_needed, &sc->sc_lock);
> }
> mtx_unlock(&sc->sc_lock);
> kthread_exit(0);
> }
>
> static void
> pff_kill_kthread(struct pff_softc *sc)
> {
> if (sc->sc_flags & SC_KTHREAD) {
> mtx_lock(&sc->sc_lock);
> sc->sc_kthread.sck_exit = 1;
> cv_signal(&sc->sc_kthread.sck_needed);
> msleep(sc->sc_kthread.sck_proc, &sc->sc_lock, PPAUSE | PDROP,
> "pffktc", 0);
> }
> }
>
Or simpler:
foo_kill():
error = kthread_suspend(p, kproc_shutdown_wait * hz);
if (error == EWOULDBLOCK)
printf("timed out\n");
foo_thread():
for (;;) {
mtx_unlock(&bdlock);
kthread_suspend_check(bufdaemonproc);
...
mtx_lock(&bdlock);
if (numdirtybuffers <= lodirtybuffers)
msleep(&bd_request, &bdlock, PVM, "psleep", hz);
--
Nate
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