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Message-ID: <20070810085611.GA11639@elte.hu>
Date: Fri, 10 Aug 2007 10:56:11 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Jarek Poplawski <jarkao2@...pl>
Cc: Thomas Gleixner <tglx@...utronix.de>,
John Stoffel <john@...ffel.org>, linux-kernel@...r.kernel.org,
shemminger@...ux-foundation.org, vignaud@...dmail.fr,
marcin.slusarz@...il.com, torvalds@...ux-foundation.org,
akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
linux-net@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: 2.6.23-rc2: WARNING: at kernel/irq/resend.c:70
check_irq_resend()
* Jarek Poplawski <jarkao2@...pl> wrote:
> > > [...] Well, there are probably (but need more testing) two other
> > > solutions: _SW_RESEND and disabling without delay for levels
> > > only...
> >
> > IIRC Marcin tested software-resend and it didnt fix the hang. That
> > strongly points in the direction of a driver bug (or a genirq bug)
> > being made more prominent by the genirq change - not any hardware
> > detail such as the APIC vector-retrigger sequence.
> >
> > While we'd like to see the suspected driver bug (or any higher level
> > genirq bug) fixed, we'll undo the effect of the genirq change
> > (because it is causing a regression). We'll also add a separate,
> > optional irq-debugging feature that generates high-rate interrupts
> > on any shared irq line. (and thus artificially stresses the
> > robustness of the driver and the genirq layer against spurious
> > interrupts.)
>
> Not exactly so... I've send modified version of your software-resend
> patch, and it seems to work OK.
ah, i completely missed that! Thanks :-)
this changes the picture completely and makes the IO-APIC/local-APIC hw
retrigger code/logic the main suspect. I think you right that it's quite
bogus to hw-retrigger level irqs, and that could be confusing the
IO-APIC (or the local APIC, or both).
and i think i see why my first sw-resend patch didnt do the trick:
> > - if (!desc->chip || !desc->chip->retrigger ||
> > - !desc->chip->retrigger(irq)) {
> > + if (desc->handle_irq == handle_edge_irq) {
> > + if (desc->chip->retrigger)
> > + desc->chip->retrigger(irq);
> > + return;
> > + }
> > #ifdef CONFIG_HARDIRQS_SW_RESEND
we used the hw-resend method unconditionally, right?
Ingo
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