Date: Mon, 28 Apr 2003 17:16:23 -0400 (EDT) From: John Baldwin <jhb@FreeBSD.org> To: "M. Warner Losh" <imp@bsdimp.com> Cc: shinra@j10n.org Subject: Re: panic: sleeping thread owns a mutex Message-ID: <XFMail.20030428171623.jhb@FreeBSD.org> In-Reply-To: <20030428.150307.83622281.imp@bsdimp.com>
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On 28-Apr-2003 M. Warner Losh wrote:
> In message: <XFMail.20030428164942.jhb@FreeBSD.org>
> John Baldwin <jhb@FreeBSD.org> writes:
>:
>: On 26-Apr-2003 AIDA Shinra wrote:
>: > My kernel always panics when I remove my wi pccard (WLI-PCM-S11).
>: > I am using OLDCARD and enabling hw.pcic.intr_path=1. With NEWCARD no
>: > cards work. I reported this bug 2 weeks ago but even today's kernel
>: > panics in exactly the same way. Anyone experiencing the same problem?
>: > Or just my misconfiguration?
>:
>: Can you try this patch:
>:
>: Index: if_wi.c
>: ===================================================================
>: RCS file: /usr/cvs/src/sys/dev/wi/if_wi.c,v
>: retrieving revision 1.137
>: diff -u -r1.137 if_wi.c
>: --- if_wi.c 10 Apr 2003 07:55:55 -0000 1.137
>: +++ if_wi.c 28 Apr 2003 20:39:37 -0000
>: @@ -486,10 +486,10 @@
>: ifmedia_removeall(&sc->sc_media);
>:
>: ieee80211_ifdetach(ifp);
>: + WI_UNLOCK(sc);
>: bus_teardown_intr(dev, sc->irq, sc->wi_intrhand);
>: wi_free(dev);
>:
>: - WI_UNLOCK(sc);
>: #if __FreeBSD_version >= 500000
>: mtx_destroy(&sc->sc_mtx);
>: #endif
>:
>: It is not ok to hold a lock when calling bus_teardown_intr() or
>: bus_setup_intr().
>
> This brings up another problem.
>
> If wi is on a shared interrupt, what happens if an interrupt comes in
> while the device is being torn down? Eg, as soon as you drop that
> lock, the wi_intr gets the lock and bad things happen at the
> mtx_destroy potentially. How do we keep from racing?
Set a flag in your driver before you drop the wi lock that the
wiintr() function can check and bail out immediately if it is set.
For example:
foo_detach()
{
...
sc->sc_dead = 1;
FOO_UNLOCK(sc);
bus_teardown_intr(...)
...
}
foo_intr()
{
FOO_LOCK(sc);
if (sc->sc_dead) {
FOO_UNLOCK(sc);
return;
}
...
}
--
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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