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Date: Fri, 16 Jul 2004 23:29:58 -0600 (MDT)
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To: green@freebsd.org
From: "M. Warner Losh" <imp@bsdimp.com>
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cc: current@freebsd.org
Subject: Re: pccbb crashes when detaching (unsafe interrupt handler)
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In message: <20040715180854.GZ1626@green.homeunix.org>
            Brian Fundakowski Feldman <green@freebsd.org> writes:
:  	if (sc->flags & CBB_CARD_OK) {
: +		int needgiant = 0;
: +
: +		sx_slock(&sc->intrsx);
:  		STAILQ_FOREACH(ih, &sc->intr_handlers, entries) {
: -			if ((ih->flags & INTR_MPSAFE) == 0)
: -				mtx_lock(&Giant);
: -			(*ih->intr)(ih->arg);
: -			if ((ih->flags & INTR_MPSAFE) == 0)
: -				mtx_unlock(&Giant);
: +			if ((ih->flags & INTR_MPSAFE) == 0) {
: +				needgiant = 1;
: +				break;
: +			}
: +		}
: +		if (!needgiant) {
: +			STAILQ_FOREACH(ih, &sc->intr_handlers, entries)
: +				(*ih->intr)(ih->arg);
: +			sx_sunlock(&sc->intrsx);
: +			return;
:  		}
: +		sx_sunlock(&sc->intrsx);
: +		mtx_lock(&Giant);
: +		sx_slock(&sc->intrsx);
: +		STAILQ_FOREACH(ih, &sc->intr_handlers, entries)
: +			(*ih->intr)(ih->arg);
: +		sx_sunlock(&sc->intrsx);
: +		mtx_unlock(&Giant);
:  	}
:  }

I also don't like this patch because it takes out GIANT for the
duration of ALL handlers, not just the ones that need that.  Why is
that necesary?

Warner